SDSU Geological Sciences - Department Blog

SDSU - Department of Geological Sciences -Seminar - Stephen Self

2010-03-09T15:58:00.001-08:00

Quoted from http://www.geology.sdsu.edu/seminars/spring10/03_17_10.html
SDSU - Department of Geological Sciences -Seminar - Stephen Self

Super-eruptions:Volcanic Activity with a Global Impact

Stephen Self

Volcano Dynamics Group
Department of Earth Science
The Open University
Senior Volcanologist, US NRC

Wednesday, March 17th, 2010

Every now and again, Earth suffers from tremendous explosive volcanic eruptions, much bigger than those witnessed in modern times. Although the return period for such events is long, perhaps every 10-100,000 years depending on the size, it is statistically more likely that Earth will next experience a large super-eruption (defined here as one producing more than ~ 450 km3 of rhyolitic magma) than a large meteorite impact. Depending on where the volcano is located, the effects of such an event will be felt worldwide, or at least by a whole hemisphere, and the associated phenomena will spread quickly within a couple of weeks. These effects include temporary darkness with severe reduction in amounts of solar radiation reaching the surface, unseasonal cooling and warming coupled with strange weather patterns, and, of course, widespread ash fallout. Major disruptions of services that our society depends upon can be expected for periods of months, to even a few years.

Past explosive super-eruptions, including the latest very large one, the Toba event in Sumatra 74,000 years ago, will be discussed, as well as some of the impacts of such events. Another type of super-eruption has also affected our world, but at times in the distant past. These are flood basalt events, vast lava flow-producing eruptions that have occurred in 1-2 million-year-long episodes throughout Earth history. Such events have occurred every few tens of million-years or so and seem somehow to be related to mass extinctions of life on Earth. Possible linkages between these two time-series of events will also be discussed.

The environmental effects of the largest historic eruptions, such as Tambora and Laki, can be usefully used as small-scale analogs for the impact of much greater volcanic events. The Laki (Iceland) eruption, which can be viewed as a small-scale flood basalt analog, took place at a high latitude and impacted the whole northern part of the North Hemisphere for several years. We must ask: Is our global society ready for the next super-eruption?

Dr. Self has studied volcanic rocks in many parts of the world, concentrating on the products of explosive eruptions, large (flood) lava effusions, and the impact of volcanism on the atmosphere. His research interests include mechanisms and deposits of super-eruptions. Dr. Self holds visiting professorships at The Open University, United Kingdom, and the University of Hawaii. He was formerly chair in volcanology at The Open University (2001-2007) and past leader of the U.K.'s Volcanic and Magmatic Studies Group. Dr. Self is a fellow of the Geological Society, London, member of the American Geophysical Union, and life member of the International Association of Volcanology and Chemistry of Earth's Interior. He is the author of numerous papers and articles in both specialty, and more general, scientific journals.

The Daily Aztec - New joint doctoral programs

2010-03-09T12:59:00.001-08:00

Quoted from http://www.thedailyaztec.com/city/new-joint-doctoral-programs-1.2184938:

The Daily Aztec - New joint doctoral programs

New joint doctoral programs

By Janel Bruan, Contributor

Published: Tuesday, March 9, 2010

Updated: Tuesday, March 9, 2010

Glenn Connelly / Photo Editor

San Diego State will soon offer two new joint doctoral programs, evolutionary biology and geophysics. Both programs are accepting students for next semester.

San Diego State is classified as a doctoral research university, and for a good reason.
Evolutionary biology and geophysics have joined the ranks as two new joint doctoral programs after being approved late last month.

It’s been 50 years since the creation of the Master Plan for Higher Education in California, which reserved the granting of doctoral degrees for the UC system and assigned the CSU system to train students at the master’s level. The caveat, which SDSU has taken advantage of, is that the plan allows CSUs to partner with doctoral-granting universities to create joint doctoral programs.

The first joint doctoral program was established in 1964 between chemists at SDSU and UCSD. The two universities created a partnership that allowed others that weren’t permitted to issue a doctoral degree the opportunity to join with them. The Ph.D.’s issued would be given through both universities simultaneously.

Sixteen joint doctoral programs have been established between CSU and UC schools, 14 of which are at SDSU. The last full program to be approved was computational sciences with Claremont Graduate University in 2002.

“The Ph.D. programs are a defining feature of SDSU,” Vice President for Research and Dean of Graduate Affairs Thomas Scott, Ph.D., said.

Whereas the Carnegie Foundation for the Advancement of Teaching classifies the other 22 CSUs as masters institutions, it classifies SDSU as a doctoral research university with high research activity, according to Scott.

Evolutionary biology is offered as a joint program with UC Riverside.

“Southern California is internationally recognized as an area with one of the world’s greatest biodiversity,” Annalisa Berta, program coordinator for the SDSU / UC Riverside joint doctoral program, said. “We have a very strong Masters of Science program in evolutionary biology and we wanted to build on that to offer talented doctoral students the opportunity of coming to SDSU to study molecular evolution, genomics, paleontology, population biology and systematic.”

Each program has its own curriculum. Students who will take evolutionary biology will spend their first year at SDSU and the next year at UC Riverside taking classes as well as working in the lab. The remaining years will be spent back at SDSU working on their research.

“Evolutionary biology is a very broad, diverse field,” Berta said. “It is especially relevant in society today. We know we are losing biodiversity due to human activities. In order to know what we’re losing we have to know what we have that is how to generate and maintain biodiversity.”

Berta said the program will also offer training in comparative genomics, which is the study of gene structures of different species and allows the study of the evolution of infectious diseases.

Students in the geophysics program will be collaborating with the Scripps Institute of Oceanography at UC San Diego.

Both programs took about 10 years to develop and proceed through all the levels of academic administrative review.

“The Ph.D. programs drive the designation of being a doctoral research university,” Scott said. “The faculty members from the Ph.D. programs are the ones that bring the disproportionate amount of our external funding that allows research to thrive. They really are the driving force behind what has become a major research university. It’s critically important for us to keep these healthy and continue to develop them as much as we can.”

Evolutionary biology and geophysics are both accepting students for next fall.

SDSU is currently in the process of developing more joint doctoral programs, according to Scott.

San Diego State University - Department of Geological Sciences - Joint Doctoral Program in Earthquake Science and Applied Geophysics

2010-03-09T12:58:00.001-08:00

Quoted from http://www.geology.sdsu.edu/jdp/:

San Diego State University - Department of Geological Sciences - Joint Doctoral Program in Earthquake Science and Applied Geophysics

Geophysics
Earthquake Science and Applied Geophysics
Joint Doctoral Program

A new, challenging program of graduate study leading to a Joint Ph. D. in Geophysics has been initiated by the University of California, San Diego, Scripps Institution of Oceanography and San Diego State University. The program will start in the Fall of 2010.

THE PROGRAM
A joint graduate group from the Geophysics Program of Scripps Institution of Oceanography at the University of California, San Diego (UCSD) and the Department of Geological Sciences at San Diego State University (SDSU) will offer a Joint Doctoral Program in Geophysics beginning in fall 2010. The complementary specialties and ongoing, vigorous collaborations between the two groups result in two focus areas: earthquake science and applied geophysics. Integrating geophysics at UCSD and SDSU will provide outstanding opportunities for students to develop the skills needed to address important local, regional, and global societal problems where geophysics can contribute to the solutions. Strong capabilities will be in:

earthquake-hazard investigations (incorporating tools such as observational and computational seismology, airborne and satellite-based geodesy and remote sensing, and earthquake geology), and
energy, resource, and environmental exploration methods (mainly land and marine seismology and electromagnetics).

Graduates of the program will be prepared to begin rewarding geophysics careers and assume leadership roles as university faculty, government scientists, and industry researchers. Joint UCSD and SDSU committees will administer and monitor the admission, advising, evaluation, graduation, and all other academic processes related to the joint doctoral program. Students will spend at least one academic year of residency at each campus. A Doctor of Philosophy (Ph. D.) degree in Geophysics will be awarded upon completion of the program in the names of The Regents of the University of California on behalf of the UCSD and The Trustees of the California State University on behalf of SDSU. The SDSU graduate cataloque description of the program can be viewed here pdf.

THE COMMUNITY
Scripps Institution of Oceanography at UCSD is located on the Pacific Ocean in La Jolla, California 24 kilometers from SDSU which is 19 kilometers east of downtown San Diego. San Diego enjoys a reputation for a highly desirable climate and life style. There are major cultural attractions such as music, dance, and theater performances and galleries exhibiting all types of visual works of art. San Diego is also well-known for its museums, theme parks, and a world-class zoo. Major spectator and participant sports abound at both the professional and amateur levels. The near-by ocean, mountains, and deserts provide an unusually diverse variety of yearround outdoor activities.

THE UNIVERSITIES
More than 33,000 students make SDSU one of the largest schools in the 23-campus California State University System. SDSU is unique within the system because of its large research effort and 16 joint doctoral programs. SDSU was ranked the number one small research university in the nation by Academics Analytics using the faculty scholarly productivity (FSP) index. This index ranks UCSD as 11th in the large research university category. UCSD has over 22,000 students and ranked 7th in the 2008 U. S. News and World Report ratings of the country’s top public national universities; within the geophysics and seismology specialty, the UCSD Scripps program ranked 5th overall.

FINANCIAL SUPPORT
Annual stipends will be provided for all joint Ph. D. students, as will be the full cost of tuition. Students will also receive complete health benefit packages.
Prospective students for Fall 2010 are encouraged to send their inquiries to: Steven Day
Department of Geological Sciences
San Diego State University
San Diego, CA 92182-1020
day@moho.sdsu.edu

Temblor in Chile gives California insight - SignOnSanDiego.com

2010-03-04T12:23:00.001-08:00

Quoted from http://www.signonsandiego.com/news/2010/mar/04/temblor-in-chile-gives-california-insight-on/:

Temblor in Chile gives California insight - SignOnSanDiego.com

Temblor in Chile gives California insight

By Scott LaFee, UNION-TRIBUNE STAFF WRITER

Thursday, March 4, 2010 at 12:59 a.m / AP

Soldiers patrol in Concepcion , Chile, Wednesday, March 3, 2010. An 8.8-magnitude earthquake struck central Chile early Saturday. The government sent soldiers and ordered a 6 p.m. to -noon curfew to quell looting. (AP Photo/ Natacha Pisarenko)

When an earthquake is powerful enough to shift Earth’s axis, even the toughest building codes in the world won’t stand tall.

The Saturday temblor in Chile registered a magnitude of 8.8. It was the world’s fifth-largest quake since 1900, strong enough to tweak the planet’s axis more than 3 inches and speed its spin ever so slightly.

Chile’s stringent building codes appear to have limited the quake’s worst effects to mostly older, seismically susceptible structures. They also may have provided a peek into how California might fare in a massive temblor.

In dealing with their long, mutual history of unsettled ground, Chile and California have created some of the toughest, most rigorously enforced seismic building codes and design standards in the world. But those rules and laws are no guarantee of safety, scientists and engineers said.

“People think the codes are intended to eliminate damage. They aren’t,” said Tom Rockwell, a professor of geological sciences at San Diego State University. “They’re meant to mitigate collapse and death. If we have a large earthquake, there will be damage. The hope is that it will not be deadly or catastrophic.”

Earthquake standards and building codes in California reflect an always-evolving assessment of risk and the function and value of different kinds of infrastructure, said Jorge Meneses, chairman of the seismic and geohazards practice group in the San Diego offices of Kleinfelder Inc., a national construction and engineering company.

The degree of acceptable damage depends on the structure’s importance, he said.

While modern homes may not crumble in a temblor, they could still suffer irreparable damage and have to be torn down, Meneses said. “Things like bridges, highways and hospitals are designed to withstand some damage and remain operating because they are vital to any recovery. And something like a nuclear power plant is extremely engineered because even the smallest amount of damage might have catastrophic consequences.”

Then there are the older structures.

“Some people think we don’t have ‘bad buildings’ in California,” said Richard McCarthy, director of the state’s Seismic Safety Commission. “We have thousands of them — structures made of unreinforced masonry or concrete or built to now-inadequate standards and not retrofitted. They’re all vulnerable to coming down.”

A major temblor in California is inevitable.

The U.S. Geological Survey said there’s a more than 99 percent chance that one or more quakes with a magnitude of at least 6.7 will occur somewhere in the state during the next 30 years. The chance of a quake registering 7.5 or greater in that time is 46 percent, and the epicenter would most likely be in Southern California.

But a “Big One” in California would not be like a big quake in Chile. The southern San Andreas fault zone, which extends from the Salton Sea to the town of Parkfield in Monterey County, poses the greatest seismic threat. But it isn’t capable of producing a magnitude-8.8 temblor, seismologists said.

California’s plate tectonics differ fundamentally from Chile’s. The San Andreas fault grinds horizontally rather than subducting — one plate diving below another. Also, the planet’s crust below California is thinner.

“To get a really big quake, you need a very large area and a lot of displacement,” Rockwell said. “The crust (beneath California) isn’t thick enough. Even in a worst-case scenario, I don’t think we would see anything larger than an 8.0 or 8.1.”

California has recorded just two earthquakes approaching magnitude 8: the 7.9 Tejon quake in 1857 and the 7.8 San Francisco quake in 1906.

Locally generated quakes tend to be much smaller, in the range of magnitude 3 to 5, though some active offshore fault zones may be capable of generating quakes of up to 7.7.

The deeper, stronger temblors in Chile often last for up to two minutes, while California quakes typically persist for 10 to 15 seconds, said Frieder Seible, dean of the Jacobs School of Engineering at the University of California San Diego and an international expert on bridge and highway seismic safety.

Still, researchers such as Seible said every strong quake is potentially devastating and that most offer new insights. Both the magnitude-6.9 Loma Prieta temblor in 1989, which killed 63 people and caused $6 billion in damage, and the 6.7 Northridge quake in 1994, which killed 72 people and caused $20 billion in damage, resulted in significant revisions to seismic standards and building codes.

Earthquake damage is essentially the result of seismic motions beneath a structure, the nature of the soil it was built on and its construction.

In the Loma Prieta quake, 42 people died when a half-mile portion of the Cypress Freeway collapsed. The section had been constructed on man-made fill layered over soft mud. Adjacent sections of the freeway, built upon older, firmer sand and gravel deposits, didn’t collapse.

“We learn new things after every quake, and much of it has been implemented, such as the huge, $16 billion retrofitting effort of bridges and highways since 1989,” said Jose Restrepo, a UCSD professor of structural engineering. “I think new homes, too, are now well-constructed and would perform OK in a quake.”

Scott LaFee: (619) 293-1259; scott.lafee@uniontrib.com

An earthquake would be our “Katrina” :: The Fallbrook Village News

2010-02-26T10:25:00.001-08:00

Quoted from http://www.thevillagenews.com/story/45720/:

An earthquake would be our “Katrina” :: The Fallbrook Village News
An earthquake would be our “Katrina”

Thursday, February 25th, 2010.
Issue 08, Volume 14.
We are aware of the devastation associated with a mega mine like Liberty quarry. One subject, however, has been glossed over; earthquakes.
The Elsinore fault runs along the hills next to the proposed quarry site. Scientists say, "If you are not sure it will not cause harm, don’t do it."
Geologists and seismologists agree; earthquakes are induced in five major ways. Three ways are, "fluid extraction from the earth, mining or quarrying." ("New Dawn" magazine)
Studies by Dr. Klose of Columbia University show excavating the earth’s crust to a depth of over 1000 feet may cause earthquake faults to become active.
Tom Rockwell, SDSU geologist and expert on the Elsinore fault zone, stated, "Scientists believe the Elsinore could trigger a quake big as 7.5."
Scientists with Southern California Earthquake Center say, "There is an 11 percent chance over the next 30 years this fault will trigger an earthquake paralleling Northridge.
Mary Moreland, Riverside County Emergency Services Director, said, "Disaster officials fear a major quake. An earthquake would be our ‘Katrina.’"
Lucy Jones, lead Southern California Scientist for U.S. Geology Survey, Pasadena, said, "The smaller Elsinore fault poses a threat locally in Southwest Riverside County. The Elsinore sits under Temecula and Murrieta.
With some of these perceived natural occurrences (exception being quarries) could it be that we, as humans, are not managing the earth properly and, when earthquakes occur, we have forgotten about "cause and effect?"
"We learn geology the morning after the earthquake." (Emerson)
Jerri Arganda

SDSU - Department of Geological Sciences Alumni Field Trip 2010

2010-02-22T13:56:00.001-08:00

24th. ANNUAL SDSU GEOLOGY FIELD TRIP
LANDSLIDES IN THE VICINITY OF CLARK LAKE & COYOTE MOUNTAIN, ANZA BORREGO STATE PARK
MARCH 26TH, 27TH & 28TH, 2010

The 24th Annual SDSU Geology Alumni Field Trip/Campout will be in Anza Borrego State Park this year. Nissa Morton, a graduate student at SDSU, working for Dr.Tom Rockwell on the San Jacinto Fault and Mike Hart, San Diego's Planetary/Local Landslide Expert, will be leading this year's trip. Clark Lake was not accessible except by kayak as of February 1st, 2010 so itinerary may vary depending on future storm events.

Seismic activity serves as a major trigger for land-sliding in areas of steep topography. Northeast of Borrego Springs, large, deep-seated landslides have occurred in granitic and metamorphic rock on Coyote Mountain and along the southwestern side of the Santa Rosa Mountains. This area is located within a complex zone of conjugate strike-slip faulting that is locally defined by activity on the Coyote Creek, Coyote Mountain, and Clark faults along with several northeast-striking cross faults. The field trip will examine the geomorphic and structural features of these landslides and consider the failure mechanisms needed to produce them.

The Field Trip will start Saturday Morning March 27th, 2010 at 10:00 AM on top of the Visitors Center at the Anza Borrego State Park Headquarters. Look for the flagpole, just past the flagpole coming from the parking lot there is a path to your right that leads you on top of the visitor's center. We will do some arm-waving there and then caravan/carpool out to the base of Coyote Mountain and hike up to examine the morphology of the landslides so plan on packing a lunch. Sunday, if the lake level is low enough to allow vehicles to pass (4-Wheel Drive recommended for this part of trip), we will go up towards Rockhouse Canyon to look at more landslides and possibly some petroglyphs. If the lake level is still high and you have not been to the visitors center I think you will enjoy just hanging around there for a couple of hours and maybe taking your time driving home to look for wildflowers.

We will be camping at the main Borrego Palm Canyon Campground just west of the town of Borrego Springs. The Alumni Group will have one Group site reserved for Friday, Saturday and Sunday night and one additional site for Saturday Night. I cannot guarantee additional spaces nearby so you may have to occupy and pay for individual sites near the Group Camp Ground if we have a large crowd. There are restrooms and solar showers close to the Group Site but you need quarters for the showers so plan ahead! Please observe all Park Rules Regulations which are posted at each site. Each site has several tables, BBQ and fire ring for burning wood (not provided so bring your own). Highs and lows in late March can be in the mid 80's down to the high 40's so be prepared.

DIRECTIONS: Hopefully you can find your way to Borrego Springs!? >From the traffic circle just go west and watch for signs to main campground or visitor center depending on where you are headed.

COMMUNICATIONS: There appears to be phone service in much of the campground but you may need to walk around a bit to find it. If you have a Family Radio Service (FRS) radio we will be monitoring channel 11with no Private Tones programmed in them. The Palomar Amateur Radio Repeater, 147.030 + (103.7 pl) and 2 Meter simplex 146.520 will also be monitored.

SUPPLIES/SERVICES/FUEL: All are available in Borrego Springs 7 days a week during normal business hours as per John Petersen an SDSU Alumni who now is the proud owner of his “Second Home” in Borrego Springs.

If any of our Alumni are interested in becoming involved with any of our Alumni Activities, like to assist with future trips or has a special place in mind that would be good for a future Alumni Field Trip please let me know. If you have any questions regarding this trip email or call me. Joe Corones, Alumni Field Trip Chairman. jcorones@gmail.com , Home (858)-484-3582, Cell (858)-603-5545.

SDSU - Department of Geological Sciences -Seminar - Anthony J. Park

2010-02-09T10:57:00.001-08:00

Quoted from http://www.geology.sdsu.edu/seminars/spring10/02_10_10.html:

SDSU - Department of Geological Sciences -Seminar - Anthony J. Park
Patterned mineral deposits on Earth and Mars
Anthony J. Park
Sienna Geodynamics and Consulting, Inc.
Computational Science Research Center (CSRC), San Diego State University
Wednesday, February 10th, 2010

Well-exposed Jurassic Navajo Sandstone iron oxide concretions preserve important diagenetic records of groundwater flow and water–rock interactions. Field relationships, precipitation patterns, and geometries of the Navajo concretions provide the basis for input parameters in numerical computer simulations and laboratory chemical bench tests. Although field geometries are very difficult to replicate, numerical simulations and laboratory experiments examine end results such as nucleation and growth of iron oxide concretions, produced from known input parameters. Three numerical simulations show the development of periodic self-organized nucleation centers through Liesegang-type double-diffusion of iron and oxygen. This numerical model simulates a scenario where oxygen is provided by shallow fresh water and iron is sourced from deeper reduced formation water. Concretions form in the region where the two waters interact with each other. Model sensitivities show that advection of water is an important mechanism for supplying the iron, and that acidic conditions in the iron-charged water can cause iron to stay in solution longer to produce nucleation centers that are farther from the input source. Laboratory bench tests with reactions of FeSO4 or Fe(NO3)3 with KOH show how the precipitation of hydrated iron sulfates or iron-hydroxides may form rinds around an initial, spherical source of iron (i.e. nucleation center). These rinds may show inward growth depending on the concentration of the iron source in relation to the surrounding fluid. A number of complex factors such as concentration and flux, time, and multiple events can create banded patterns during rind growth. Comparisons of the terrestrial examples with numerical and laboratory models have strong implications for understanding similar hematite concretions on Mars.

Thesis Defense - Fall 2009 - Nicole Velasco

2009-12-14T11:30:00.000-08:00

Bulk and Elemental Mass Change in Development of Gabbroic Corestone and Saprolite near the Elsinore

Nicole Velasco

B.S. Candidate

Department of Geological Sciences

San Diego State University

Advisor Dr. Gary Girty

Thesis Defense - Fall 2009 - Marck Maroun

2009-12-14T11:29:00.000-08:00

Major and minor elemental analyses of distal channel deposits from the Late Devonian marine Alamo Impact Event

Marck Maroun
B.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Dr. Jared Morrow

ABSTRACT
This study determined the geochemical signal—major and trace element composition as well as a potential extraterrestrial component, iridium—of distal, onshore channel deposits of the Alamo Breccia. The Breccia formed by the early Late Devonian—early Frasnian, ~382 Ma—Alamo Impact Event, which was centered in an oceanic off-carbonate platform site in south-central Nevada. Twenty-eight samples were analyzed—sixteen from the Alamo Breccia channel deposits and twelve from above and below—as a representative of the Alamo Impact Event stratigraphy. The Breccia shows a wide range of concentrations in major, trace and rare earth elemental compositions, yet this same range is present, but in significantly lower concentrations, in normally deposited pre- and post-event carbonate layers below and above the Breccia. Results clearly indicate an iridium (Ir) anomaly—peaking at 190 ppt—as well as relative enrichment in other siderophile elements (Co, Ni, Au and Fe), chromium, and rare earth elements from within the Breccia. For the most part, the enrichments within the Breccia can be attributed to its greater siliciclastic component—from greater mud/clay and quartz sand contents—compared to carbonate rocks below and above. However, the high relative abundance of Ir in the Breccia far exceeds Ir concentrations expected solely from increased siliciclastic input, and is consistent with Ir values previously reported from other proven impact-related deposits. The Alamo Ir data are therefore interpreted to give additional supporting evidence for the impact origin of the Alamo Breccia channel deposits.

Thesis Defense - Fall 2009 - Kieri Hutchins

2009-12-14T11:27:00.000-08:00

Late Devonian Alamo Impact, Southern Nevada: Analysis of Hematite Inclusions within Quartz Grains

Kieri Hutchin
B.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Dr. Jared Morrow

ABSTRACT
The early Late Devonian (~382 Ma) Alamo event was produced by a marine bolide impact near the offshore margin of a large Paleozoic carbonate platform fringing western North America, with an impact site located in the current area of south-central Nevada. Effects of the impact, including the Alamo Breccia and related deposits, are now found in numerous mountain ranges in south-central Nevada, western Utah, and southeastern California. A key feature characterizing the Alamo deposits is the common occurrence shocked-quartz grains from impact ejecta that contain abundant inclusions of hematite after pyrite and magnetite. The sizes of the hematite inclusions and containing quartz grains found across the Alamo impact site show evidence for size sorting and a direct correlation between proximity to the impact site and inclusion size. Nine slides from eight locations proximal-to-distal from the impact were analyzed. The average size of the proximal hematite inclusions is 15.98 μm and the average size of the distal inclusions is 8.07 μm. The exceptions are the Confusion Range (CON, western UT) and Bat Mountain (BAT, SE CA) data. The CON location appears to be distal, but has an average inclusion size of 15.4 μm. This anomaly is possibly due to irregular impact plume movement. The BAT data appear to be proximal, but have an average inclusion size of 8.3 μm. In the Late Devonian this area was distal, but post-impact strike-slip faulting has moved this impact breccia block to the northwest. The Alamo is one of the only known impact sites with such hematite inclusions in the shocked quartz grains. These inclusions are useful in supporting previous estimates of the impact size and may provide a valuable tool for tracking proximal-to-distal fallout from the event.

Thesis Defense - Fall 2009 - Michelle Dooley

2009-12-14T11:23:00.000-08:00

Geologic Mapping and Petrochemical Stratigraphy of Southern Warner Valley, Southern Oregon, USA

Michelle Dooley
M.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Dr. Vic Camp

ABSTRACT
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The tectonomagmatic evolution of the northwestern margin of the Basin and Range Province is well expressed by the mafic-to-intermediate-to-silicic volcanic stratigraphy and structure of the south Warner Valley in southern Oregon. The Warner Valley, a north-south trending Basin-Range extensional graben, exposes hundreds of meters of lava flows and ignimbrites, which include Oligocene-Miocene calc-alkaline-to-mildly alkaline volcanics, mid-Miocene tholeiitic eruptions of Steens basalt, and Miocene-to-Recent eruptions of impressive basaltic andesite, trachyandesite, and trachydacite flows and tuffs, rhyolitic ignimbrites, and high-alumina olivine tholeiites (HAOT). The mid-Miocene genesis of the voluminous Columbia River Basalt Group (CRBG) began with the eruption of Steens basalt in southeastern Oregon, and was followed by effusive intermediate-to-silicic volcanism related to Basin-Range extension. Previously, the only geologic map for the Warner Valley area is the 1:250,000-scale reconnaissance map of Walker and Reppening (1968). The field area spans six USGS 1:24,000-scale quadrangles and contains a diverse volcanic sequence spanning an age range of ~20 m.y. This entire succession has been faulted and offset by both NW- and subordinate NE-trending normal faults. The NE-trending faults are associated with Basin-and-Range extension that began in the late Miocene to early Pliocene, whereas the NW-trending structures form a slightly older set of faults associated with the Eugene-Denio fault zone. The footwall of the Warner Valley is delineated by Basin-and-Range boundary faults with over 600 meters of offset, and the valley floor contains smaller normal faults bounding tilted fault blocks with gentle slopes (5-10o).
The focus of this study was to produce a detailed field map across six 1:24,000-scale quadrangles in the southern Warner Valley, and to describe in detail the field characteristics of the volcanic succession, with the intent of making a contribution to the sparse stratigraphic and petrologic database evident in this part of eastern Oregon.

SEMINAR - Kenneth S. Deffeyes

2009-10-27T10:56:00.000-07:00

PEAK OIL AND THE GREAT RECESSION

Kenneth S. Deffeyes
Emeritus Prof. of Geology
Princeton University

November 4th, 2009

In 2001, my first oil book predicted that world oil production would peak in the year 2005. The most recent data from the Energy Information Agency say that it happened! Even with the extreme spike in oil prices, the year 2008 produced less oil than 2005. Production for the first half of 2009 is even lower. The invisible hand of economics has become the invisible fist; pounding the world economy down to match the reduced oil supply.
In 1956, M. King Hubbert correctly predicted that United States oil production would peak in the year 1970, although the mathematics that he used was complicated. In my second oil book, in 2005, I developed an exactly equivalent mathematical derivation using three lines of high-school algebra. My third oil book is due out in the spring of 2010. Stay tuned.
Our existing transportation system is heavily dependent on oil and our versatile petrochemical industry turns out a huge range of useful products. Agriculture is heavily dependent on oil and natural gas. During this recession, China is shopping internationally for mineral resources, especially oil.During the last few years, mature petroleum source rocks have been developed as important new sources of natural gas, although they are called “shales.” Uranium is available in sufficient amounts to support an expanded network of nuclear reactors.
A significant shortage of petroleum geologists, geophysicists, and engineers is developing as the previous generation is retiring. A banker, Matthew Simmons, calls it “no freshman class. Redeveloping existing oilfields is a remaining opportunity for an individual to become wealthy; big Texas rich.

New Photos Online - Stewart Lithia Mine

2009-10-06T13:03:00.000-07:00

Geology 200 - Stewart Lithia Mine

Alumni News - Africa Oil Corp.: Corporate Update

2009-09-15T15:01:00.000-07:00

VANCOUVER, BRITISH COLUMBIA -- 09/15/09 -- Africa Oil Corp. (TSX VENTURE: AOI) ("Africa Oil" or "the Company") is pleased to announce the appointment of the following new board members and senior officers:
James Phillips, Vice President Exploration
Before joining Africa Oil, Mr. Phillips was Vice President Exploration Africa and Middle East for Lundin Petroleum AB. Mr. Phillips is a graduate of the University of California, Berkeley and San Diego State University where he obtained BS and MS degrees, both in Geology. He has over 24 years of experience in the oil industry including senior technical and managerial positions with Shell Oil Company and Occidental including heading up Oxy's African exploration new ventures.

source: EarthTimes

New Photos Online

2009-09-15T15:00:00.000-07:00

Geology 200 - Lot D Brunton Exercise

Webinar - John Mayhew

2009-07-27T09:26:00.000-07:00

Goodness-of-fit Criteria for Broadband Synthetic Seismograms, With Application to the 2008 Mw5.4 Chino Hills, CA, Earthquake

John Mayhew
M.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Dr. Kim Bak Olsen

http://www.scivee.tv/node/12105

ABSTRACT
We present a goodness-of-fit measure for broadband ground motion time histories. As is the case with the goodness-of-fit measure proposed by Anderson (2004), our method includes a set of user-weighted metrics such as peak ground motions, response spectrum, the Fourier spectrum, cross correlation, and energy release measures. The scale for the goodness-of-fit ranges from near 0 to 100 (perfect fit). We apply the method to broadband (0-10Hz) synthetic seismograms for the 2008 Mw5.4 Chino Hills, CA, earthquake, generated by combining a deterministic low-frequency simulation and high-frequency scattering functions at 33 strong-motion recording sites. We find generally favorable average long-period GOF_MO values for the event, in agreement with the waveform fits. Of particular importance, relatively good fits obtained in the Chino basin provide some confidence in the strong wave-guide effects from this area obtained for scenarios of northwestward-propagating ruptures on the southern San Andreas fault (TeraShake, ShakeOut). At shorter periods, the goodness-of-fits fall above our general (ad-hoc) acceptance level at about 2/3 of the selected sites for the event. An additional metric with specific interest for structural engineers, the ratios of inelastic versus elastic displacements, is also included in our method. We find an overall goodness-of-fit level for these ratios similar to that obtained from the average set of metrics for the event. Our results suggest that the accuracy of broadband scenario simulations for greater Los Angeles is entering the range required for structural engineering applications, with some room for improvement.

Thesis Defense - Fall 2009 - John Mayhew

2009-07-20T14:21:00.000-07:00

Goodness-of-fit Criteria for Broadband Synthetic Seismograms, With Application to the 2008 Mw5.4 Chino Hills, CA, Earthquake

John Mayhew
M.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Dr. Kim Bak Olsen

Wednesday, July 22nd, 2008
GMCS 129, 10:00am

ABSTRACT
We present a goodness-of-fit measure for broadband ground motion time histories. As is the case with the goodness-of-fit measure proposed by Anderson (2004), our method includes a set of user-weighted metrics such as peak ground motions, response spectrum, the Fourier spectrum, cross correlation, and energy release measures. The scale for the goodness-of-fit ranges from near 0 to 100 (perfect fit). We apply the method to broadband (0-10Hz) synthetic seismograms for the 2008 Mw5.4 Chino Hills, CA, earthquake, generated by combining a deterministic low-frequency simulation and high-frequency scattering functions at 33 strong-motion recording sites. We find generally favorable average long-period GOF_MO values for the event, in agreement with the waveform fits. Of particular importance, relatively good fits obtained in the Chino basin provide some confidence in the strong wave-guide effects from this area obtained for scenarios of northwestward-propagating ruptures on the southern San Andreas fault (TeraShake, ShakeOut). At shorter periods, the goodness-of-fits fall above our general (ad-hoc) acceptance level at about 2/3 of the selected sites for the event. An additional metric with specific interest for structural engineers, the ratios of inelastic versus elastic displacements, is also included in our method. We find an overall goodness-of-fit level for these ratios similar to that obtained from the average set of metrics for the event. Our results suggest that the accuracy of broadband scenario simulations for greater Los Angeles is entering the range required for structural engineering applications, with some room for improvement.

New Photos Online! - White Mountains

2009-06-08T09:16:00.000-07:00

Advanced Field - White Mountains

Scientists shake things up to limit earthquake destruction

2009-06-05T14:47:00.001-07:00

Pat Abbott Discusses Earthquakes in San Diego and Italy

In a matter of seconds, dozens of people were dead. Over the next hours and days, hundreds more would suffer the same sad fate.

The 6.3 magnitude earthquake that struck L’Aquila, Italy on the morning of April 6 killed 297 people and injured more than 1,100. It is estimated 11,000 buildings were damaged in some capacity. The central Italian city was home to about 72,000 people and left more than 60,000 people homeless.

Staggering figures like that make you sit up and take notice, especially when you consider that San Diego County has a whopping 41 times more inhabitants than L’Aquilla. In an earlier SDNN story, we examined the reality of living in earthquake country, just 90 miles east of the southern tip of the San Andreas Fault. The article discussed acknowledging that a big earthquake was going to hit the region, and knowing how to be best prepared for the event and what’s to follow.
The next question to address is how San Diego is working to limit the kind of death and destruction that befalls other countries, when “The Big One” hits.
Geologist and author Pat Abbott, a professor emeritus at San Diego State University, said Italy is one of the most earthquake active countries in the world. In a tectonics sense, he said, Italy is essentially a piece of Africa that is being pushed and shoved into Europe.

“That ongoing push is still going on,” he said. “It’s like being squeezed in a vice.”
But, he also said, due to the Italy’s lack of modern building codes, devastating destruction is far more likely there than in other places, namely California.
“There are lots of old buildings built out of stone and held together by simple mortar [in Italy],” he said. “It’s just a bad, bad place for earthquakes, and there’s no way around it. There are lots of cultural heritage sites; the cost to retrofit those buildings would be overwhelming. It’s hard to think of a reasonable solution of how do you protect people and cultural heritage at the same time.”
Knowing that, the charge to help make the region’s buildings safer and more able to withstand large seismic events is the passion of the structural department at UC-San Diego’s Jacobs School of Engineering.
Thanks to funding from the National Science Foundation, the school was able to build the world’s first outdoor “shake table” in 1995 at the Englekirk Center for Structural Development. The table allows for scientists to test the impact of seismic activities on structures to determine how well they perform during earthquakes. At 25-by- 40-feet, it is also the largest shake table in the United States.
“The table has been quite busy actually,” said Dr. Benson Shing, one of the project’s lead researchers and a professor of structural engineering at UCSD. “We are using it continuously, testing different materials. Most recently, we are working with stone masonry and wood-framed houses with brick veneer.”
See related:
L.A. earthquake should have San Diego taking notice
Magnitude 4.7 quake rattles nerves near Los Angeles
Shing’s crew is currently building a brick and mortar structure to shake test this July. It is a follow-up from a test that was performed in March on a similar structure (see video). The structures are similar to much of the 1920s era masonry and brick buildings that still exist in the area.
Shing said that the team looks at older building to see how they perform and newer more modern structures to see how they perform. They determine if there’s a need to improve current building code to enhance the safety. If the tests bear out improvement, they have to communicate with committees responsible for code development and get the process going.
“As structures change as the [building] codes change, and codes change based on earthquakes,” said Shing, who has more than 20 years in the structural engineering field. “And those buildings that are conforming to the most recent code are obviously expected to perform much better due to advancements in technology and other developments.”

(Photo by Eric Yates)
The shake table is built on steel plates and is operated by a below-ground system of hydraulic actuators. The actuators are powered by oil banks that can accumulate pressure and generate as much as 5,000 pounds per square inch, a measurement of pressure. The pressure activates pistons which raise the table, and has an oil-based bearing that allows it to slide horizontally with little friction, which simulated earthquake-incident motions. Researchers can test structures weighing up to 2,200 tons and as tall as 100 feet. Its hydraulic actuators are capable of shaking at speeds up to 6 feet per second, allowing it to create simulations of the most devastating earthquakes ever recorded, even some as high as 8 or 9 on the Richter scale, according to Shing.
Shing said it takes a month-and-a half for construction of a new structure. After the structures are built, they must wait one month for curing and the mounting transducers (which can measure energy and transfer it to data gathering sources) to the specimen to measure the deformation and the acceleration that occurs during the shaking.
After the test, the team analyzes the data for several months and calibrates computer models for simulation to have a better understanding for the performance of the structures. They then extrapolate that data and use those models as a means to predict the performance of existing structures.
Abbott said you never really know how structurally sound a building will be until you actually have a quake.
“The earthquake will expose what was done right, and what was done wrong,” he said.
Hopefully, thanks to Shing and his extensive work, and for the potential lives at stake, when the Big One does eventually hit, a lot more will go right.

source: Eric Yates is SDNN deputy managing editor. E-mail: eric.yates(at)sdnn.com Read more: http://www.sdnn.com/sandiego/2009-06-05/news/environment/ucsd-scientists-shake-things-up-to-limit-earthquake-destruction##ixzz0Hawo1LQD&C

Clive Dorman Appointed Department Educational Outreach Chair

2009-06-05T11:16:00.000-07:00

Clive will bring the departments expertise to the community to strengthen our education/community-based activities

SDSU is an active partner with the San Diego community and administers more than 75 programs in the areas of arts and culture, business and economic development, community-based learning, health, public safety and technology.

New Photos Online!

2009-05-31T17:57:00.001-07:00

2009 Commencement
Petroleum Geology - Bakersfield
AAPG BBQ
Alumni Banquet
Advanced Field - Otay Mountain

Thesis Defense - Spring 2009 - Loren Wimmer

2009-05-18T09:06:00.000-07:00

Scenario-Based Seismic Loss Estimation for San Diego County, Californiaspan>

Loren Wimmer
M.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Dr. Steven Day

Wednesday, May 22nd, 2008
CSL 422, 1:00pm

http://www.scivee.tv/node/http://www.scivee.tv/node/11268

ABSTRACT
A study was done to estimate seismic losses to San Diego County, California, and test the sensitivity of those loss estimates to the choice of ground motion model. The scenario chosen was a magnitude 7.1 earthquake on the Rose Canyon Fault Zone. A rupture surface for this scenario was defined following the 2002 National Seismic Hazard Mapping Program. Two types of ground motion forecasts are used as input to the loss analysis. The first type uses empirical attenuation relationships. Nine different attenuation relationships are employed and compared, three of which are from the recent Next Generation Attenuation (NGA) project. The second type of ground motion input is broadband numerical simulations. For the broadband simulation methodology three rupture directions are considered, north-to-south, south-to-north and a bilateral rupture. Using the nine attenuation relationships and three broadband simulations, 12 different ground motion estimates for the M7.1 scenario were computed. Loss estimates were made by importing each scenario into the FEMA program HAZUS-MH MR3. The analysis estimates total economic loss to be between $9.1 and $26 billion and 15 - 412 fatalities. This study shows the choice of ground motion model to have a large effect on both loss estimates and the spatial distribution of those losses. In general, using the NGA attenuation relationships reduces loss estimates by 40 – 50% when compared with the loss estimates generated using pre-NGA attenuation relationships. Broadband numerical simulations on the other hand show a wide range of total loss estimates and impact the spatial distribution of losses.

Thesis Defense - Spring 2009 - Dylan Collins

2009-05-11T10:24:00.000-07:00

Latitunal Controls on the Martian Crater Densities
Dylan Collins

B.S. Candidate
Department of Geological Sciences
San Diego State University
Dr. Brad Thomson
The Johns Hopkins Applied Physics Laboratory

Wednesday, May 13th, 2008
CSL 422, 9:40am

http://www.scivee.tv/node/11170

In order to gain new insight into Mars’ planetary dynamics, an examination of Martian crater densities as a function of latitude was completed. There are two complete crater catalogs of the Martian surface; one manually compiled by Nadine Barlow and one compiled by crater counting software created by Tomasz Stepinski and colleagues. After loading these two data sets into ArcMap 9.2, a pole-to-pole swath centered on 0˚ longitude was completed. Using equal-area trapezoids, representative size-frequency distributions (SFD) were constructed for every 5˚ in latitude. Upon comparison, the resulting two data sets had similar crater distributions, and both revealed a broader trend of thinning crater densities towards the poles. In addition, an absence of craters greater than 1.9 km was evident at the poles. From these new observations, it is concluded that either there is a deficit in impactor flux towards the poles of the planet or that there is a currently unrecognized crater modification process taking place at the poles. It is herein suggested that the Martian polar ice caps are responsible for modifying and erasing the craters near the poles. However, it would take a long time for large crater modification by ice cap transgression and regression to take place, and would require that Mars’ axial orientation has not changed for a geologically significant period of time.

Thesis Defense - Spring 2009 - Robert Edie

2009-05-11T10:22:00.000-07:00

Using XRD Peak Broadening Analysis on Quartz to Identify Shatter Cones of the Santa Fe New Mexico Impact Structure

Robert Edie

B.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Dr. Jared Morrow

Wednesday, May 13th, 2008
CSL 422, 9:00am

http://www.scivee.tv/node/11169

In addition to such large-scale features as craters and remote sensing anomalies, evidence for meteorite impact events is abundant at both micro- and mesoscopic scales. Micro-structural damage, planar deformation features, and planar fractures within quartz and other silicate mineral grains all give direct, supportive petrographic evidence for the existence of shock-metamorphic conditions associated with impact events. Planar deformation features and planar fractures can be difficult to identify. They can also be easily confused with other natural geologic patterns and misinterpreted. A diagnostic mesoscopic shock-metamorphic feature found at many impact sites are shatter cones, which are distinctive, meter-scale, horsetail-shaped, striated conical surfaces that develop at low to moderate shock pressures (i.e., ~5–25 GPa). This project investigates a new technique for identifying quartz grains along the surfaces of shatter cones that have been affected by shock metamorphism. As previously shown in laboratory and naturally shocked quartz-rich samples, peak broadening within quartz X-ray diffraction (XRD) spectra can give evidence for shock-driven sub-microscopic alteration of mineral crystal lattice structures. Well-developed shatter cones developed within quartz-rich crystalline host rocks collected from the Santa Fe Impact Structure in New Mexico were analyzed with XRD to detect evidence of shock-related spectral peak broadening. This evidence is identifiable and repeatable with the chosen data set of the project. Although highly variable, peak broadening was detected for all samples tested at specific crystal orientations. This peak broadening further supports the shock-metamorphic origin of the shatter cones. The XRD method may provide an important new tool for identifying the shock origin of possible shatter cones present at other suspected impact sites.

Thesis Defense - Spring 2009 - Justin Kerl

2009-05-11T10:20:00.000-07:00

Possible relationship of the Iron Mountain metavolcanic assemblage to the El Cajon Mtn ring complex, San Diego Country, California

Justin Kerl

B.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Dr. David Kimbrough

Wednesday, May 13th, 2008
CSL 422, 8:40am

http://www.scivee.tv/node/11165

The Cretaceous Santiago Peak Volcanics are exposed along the western edge of the Peninsular Ranges batholith(PRB) and are interpreted as the volcanic cover of the batholitic intrusions. Ring dikes are also a common feature in the western PRB and were first described almost 70 years ago (Merriam, 1941). Ring dikes and ring complexes are interpreted as subvolcanic feeder systems that represent the transition from the plutonic realm to the volcanic realm in magmatic arcs (Johnston et al., 2002). However, there has been very little work on the petrology of the ring complexes in the PRB, and in particular how they might link the intrusive and extrusive history of the magmatic arc.

This study is focused on the El Cajon Mountain ring complex which was mapped by Todd (2004) and represents the possible roots of a central-vent volcano. The hypothesis tested in this study is that the El Cajon ring complex is the root of a volcano that fed surface volcanic deposits of the nearby Santiago Peak Volcanics at Iron Mountain. The Iron Mountain metavolcanics occur as a strongly foliated and steeply dipping screen completely surrounded by batholith wallrock. Zircon U-Pb ages from the ring dikes and metavolcanic rocks yield similar ages of ~120 Ma. Here, I present whole rock major and trace element concentration data from the dikes and volcanics to test if they could be closely related to one another as indicated by the similarity of the zircon ages.

Ten samples of Iron Mountain metavolcanic rocks and two samples of El Cajon Mountain ring dikes were analyzed in this study. Whole rock chemical analyses were obtained in the SDSU Geological Sciences laboratory by X-ray fluorescence analysis. Nine of the ten Iron Mountain samples are high silica rocks with SiO2 contents averaging 72.9±2.7 wt% (1 sigma sd) corresponding to a rhyolite composition for the volcanics. The two El Cajon Mountain ring dikes similarly yield high SiO2 contents of 74.5 and 77.7 wt%. A plot of SiO2 verse K2O plot indicates the rock are arc tholeiites or calc-alkaline in character consistent with a volcanic arc origin. A plot of immobile trace elements (Nb/Y vs. Zr/TiO2) also supports a possible close relationship of the metavolcanic rocks and ring dikes.

Johnson, S.E., Schmidt, K.L., and Tate, M.C., 2002, Ring complexes in the Peninsular Ranges Batholith, Mexico and the USA: magma plumbing systems in the middle and upper crust: Lithos, v. 61, p. 187- 208.
Merriam, R., 1941, A Southern California ring-dike: American Journal of Science, v. 239, p. 365-371.
Todd, 2004, Preliminary Geologic Map of the El Cajon 30´ x 60´ Quadrangle, Southern California, USGS Open-File Report 2004-1361, Detailed Description of Map Units, version 1.0.

Thesis Defense - Spring 2009 - Jerehme Acosta

2009-05-11T10:18:00.000-07:00

Petrology of the Santiago Peak Volcanics, San Diego County, California

Jerehme Acosta

B.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Dr. David Kimbrough

Wednesday, May 13th, 2008
CSL 422, 8:20am

http://www.scivee.tv/node/11164

The Santiago Peak Volcanics (SPV) is exposed discontinuously in a belt along the western side of the Peninsular Ranges batholith in southern and Baja California. The SPV is intruded by ~125-100 Ma intrusions of the batholith and unconformably overlain by Late Cretaceous forearc basin strata of the Rosario Group. The SPV has been interpreted as the volcanic cover of the batholith and is one of the best places anywhere that genetically related volcanic and plutonic assemblages of a convergent margin arc can be studied together.
This study provides reconnaissance whole rock major and trace element data from SPV samples in areas of southern San Diego County where there is little or no data. The goal is to better constrain the nature of the volcanic arc represented by the SPV.

Twelve samples of SPV were collected from the La Mesa area to Otay Mountain near the US-Mexico border. The samples are volcanic flow rocks and lapilli tuff breccia typical of the SPV. Although original textures are visible in hand specimens, the rocks have experienced greenschist facies metamorphic overprinting.

Whole rock chemical analyses were obtained from fresh outcrop samples initially breaking up the rocks with the hydraulic RockLabs splitter/crusher to facilitate selection of approximately 90-100g of freshest homogeneous rock fragments. This material was then reduced to a fine powder using a tungsten carbide ring mill. The rock powder was used to make both a pressed pellet (for trace element analysis) and a fused disc (for major element analsis) which were analyzed using the Phillips XRF spectrometer in the Department of Geological Sciences.

The samples are strongly subalkaline and range in SiO2 from ~61 to 74 wt% which indicates they are andesite, dacite and rhyolite. The SiO2 verse K2O plot indicate the rock are arc tholeite or calc-alkaline in character consistent with a volcanic arc origin. The SiO2 versus FeOT/MgO also indicated calc-alkaline and tholeite affinities as well as the Nb/Y versus Zr/Ti plot. The composition and nature of the samples suggest derivation from nearby stratovolcanoes and/or possible caldera complexes.

Thesis Defense - Spring 2009 - Krista Muela

2009-05-11T10:15:00.000-07:00

Stratigraphy and structure of the Miocene Bear Canyon Conglomerate, Imperial County SE California: Evidence for the episodic growth of the Chocolate Mountains anticlinorium

Krista Muela
B.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Dr. Gary Girty

Wednesday, May 13th, 2008
CSL 422, 8:00am

Between Indian Pass and Picacho State Recreation Area crystalline basement is overlain by early Miocene (~23 Ma) volcanic rocks. These units are in turn unconformably overlain by undated alluvial sedimentary rocks of the informally recognized Bear Canyon conglomerate. On the north limb of the anticlinorium, three steeply dipping faults and associated splays cut this sequence of rocks consistently off setting them in a dextral sense while a fourth fault at Picacho transects both limbs of the anticlinorium. Where exposed, fault surfaces contain sub-horizontal slickenlines and offset hingelines of E-W trending folds. The three westernmost faults appear to tip out into the core of the anticlinorium. Hence, we speculate that the anticlinorium may have taken up the slip on these faults through tightening and growth. Over an ~15 km EW distance, the cumulative dextral offset on the four faults is ~3.5 - 4 km.
At Picacho, the Bear Canyon conglomerate lies on the northern limb of the anticlinorium. There the lower member of the Bear Canyon dips ~21° northward, and is unconformably overlain by the ~15° northward dipping middle member. In contrast, the unconformably overlying upper member is not tilted.
Between Carrizo Wash and Indian Pass, the Bear Canyon conglomerate lies on both the southern and northern limbs of the anticlinorium. North of the intersection between Carrizo Wash and Gatuna Wash, the Bear Canyon conglomerate dips ~17 ° NE. Northwest of Carrizo Wash, it dips ~10° - 27 ° SW. Just NW of Indian Pass, the Bear Canyon dips about ~8° - 12° southward and is interstratified with the basalts of Black Mountain. The basalts ~2 km SE of Indian Pass are transected by a major dextral strike-slip fault and dip ~20° - 57 ° SW. Published K-Ar data suggest an age somewhere between ~9.4 and ~13.6 Ma for the basalts of Black Mountain. Hence, our data imply that the anticlinorium was growing after ~9-13 Ma ago, and that it, and the dextral strike-slip faults that we have mapped, are the likely record of the development of a segment of the Eastern California Shear Zone.

WEBINAR - Matthew Sisk

2009-05-08T20:47:00.000-07:00

Chemical and Physical Characteristics of Pulverized Tejon Lookout Granite Adjacent to the San Andreas and Garlock Faults: Implications for Earthquake Physics

Matthew Sisk
M.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Dr. Thomas Rockwell

http://www.scivee.tv/node/11092

ABSTRACT
We present new detailed analysis of pulverized Tejon Lookout granite from sections adjacent to the San Andreas and Garlock faults in southern California. The granite is pulverized in all exposures within about 100 m from both faults. Chemical analyses indicate essentially no or little weathering in the bulk of the rock, although XRD analysis shows the presence of smectite. Illite, and minor kaolinite in the clay-size fraction. Weathering products may dominate in the less than 1 micron fraction. The average grain size in all samples of pulverized granite range between about 26 and 208 microns (silt to fine sand), with the size distribution in part a function of proximity to the primary slip zone. The San Andreas fault samples are generally finer than those collected from adjacent to the Garlock fault. The particle size distribution for each sample follows a pseudo power law with a continuously changing exponent, which suggests that pulverization is not simply a consequence of direct shear. This average particle size is quite coarser than previous reports, which we attribute to possible measurement errors in prior work. Our data and observations suggest that dynamic fracturing in the wall rock of these two major faults only accounts for about 1% or less of the earthquake energy budget.

Thesis Defense - Spring 2009 - Robert Gallardo

2009-05-08T17:22:00.000-07:00

Seismic Anisotropy in the Julian Schist, San Diego CA

Robert Gallardo
B.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Dr. Robert Mellors

Wednesday, May 13th, 2008
CSL 422, 9:00am

http://www.scivee.tv/node/11167

ABSTRACT
P-wave velocity measurements of a Julian Schist rock sample collected in the Laguna Mountains region of East San Diego County show significant P-wave velocity anisotropy at near surface conditions. Multiple P-wave velocity measurements were taken from orthorhombic cut sample of Julian Schist using the Tico Ultrasonic Instrument with varying parameters of length. A maximum anisotropy of 22.1% was obtained from the P-wave measurements gathered in the X, Y, and Z axes of the Julian Schist sample. Cracks within orthorhombic schist sample demonstrate the need to take measurements with increased pressure parameters as measurements made within the same axis on different locations show p-wave velocity differences of up to 54.0%. This is based on observations of varying numbers of visible cracks on the external surface of rock sample within the same axis of measurement. Increasing metamorphic grade has been known to represent increasing anisotropy within rock units and is an important factor in identifying proximity to faults, general lithologic and structural descriptions of regional rock types, and could have an effect on the Southern California Communal Velocity Model (SCCVM).

Thesis Defense - Spring 2009 - Jared Warner

2009-05-08T17:02:00.000-07:00

Biotic Response of Ostracodes to the Middle Eocene Climatic Optimum (MECO; 40.0 Ma) in the Southern Indian Ocean (ODP Site 748)

Jared Warner
M.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Dr. Stephen Schellenberg

Wednesday, May 13th, 2008
CSL 422, 11:30am

http://www.scivee.tv/node/11182

ABSTRACT
The long-term cooling trend from “greenhouse” to “icehouse” conditions through the middle-to-late Eocene (49.0 – 33.7 Ma) was interrupted by the middle-Eocene Climatic Optimum (MECO; ~40.0 Ma), a transient (~500 kyr) global warming of ~4-6 C° widely recorded in marine and terrestrial stratigraphic sections. The broad biotic response to the MECO is poorly known, with most published studies focused on planktonic protists such as foraminifera, calcareous nannoplankton, and dinoflagellates. To initiate a complementary benthic biotic perspective, we conducted a high-resolution ostracode faunal analysis (>150 mm size-fraction) through the MECO at Ocean Drilling Program Site 748 on the southern margin of the Kerguelen Plateau (~725 m paleodepth) in the southern Indian Ocean. Ostracodes are the only readily preserved deep-ocean metazoans and thereby provide a unique biotic perspective on this geographically vast ecosystem.
The ostracode faunal assemblages were assigned to three stratigraphic intervals (pre-MECO, MECO, and post-MECO) based on the nominal onset and termination of the oxygen-isotope excursion. Ostracode generic richness, Margalef’s (d), and Simpson’s Index (1/l) were all significantly lower (ANOVA; p <0.001) within the MECO interval, indicating a decrease in ostracode diversity. A Likelihood Ratio Test (LRT) was used to further evaluate the diversity loss via an ecological response versus a sampling artifact. Decline in ostracode diversity is also denoted by the disappearance of Bairdia during the MECO interval, a significant pattern revealed by the LRT. In addition, within the MECO interval, the whole-faunal percentage of smoother, less ornate genera was significantly lower while some genus-specific adult:juvenile valve ratios were significantly higher; both patterns are consistent with a hypothesized decrease in carbonate saturation during the MECO. The absence of faunal turnover and pronounced changes in faunal percentages through the MECO stands in stark contrast to ostracode assemblages previously documented during other intervals of rapid climate change (i.e., PETM)

Thesis Defense - Spring 2009 - Dale Burns

2009-05-08T16:50:00.000-07:00

The Recent Prehistoric Geochemical Evolution of Summit Lavas From Kilauea Volcano, Hawaii

Dale Burns
M.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Dr. Aaron Pietruszka

Wednesday, May 13th, 2008
CSL 422, 1:45pm

ABSTRACT
Lavas from Kilauea Volcano display rapid geochemical and isotopic variations (e.g., 206Pb/204Pb or Nb/Y ratios) on a time scale of decades to centuries. The wall of Kilauea Caldera at Uwekahuna Bluff exposes a sequence of recent prehistoric, caldera-filling lavas (erupted mostly between AD 900-1400). Here we present a detailed geochemical study (major element abundances, and Pb, Sr, and Nd isotope ratios) for lavas from the lower portion of the Uwekahuna Bluff section as well as trace element abundances for the entire section. The 206Pb/204Pb ratios of the lavas from the lower Uwekahuna Bluff display small variations that merge with an isotopic excursion towards low 206Pb/204Pb ratios in the lavas from the upper portion of the section. At least four distinct source components within the Hawaiian mantle plume are required to explain the variations in Pb, Sr, and Nd isotope ratios. Two of these components were previously thought to be restricted to the neighboring active volcanoes, Mauna Loa and Loihi Seamount. The occurrence of Mauna Loa- and Loihi-like mantle sources in Kilauea’s melting region (in addition to Kilauea’s typical mantle source) suggests that (1) the Hawaiian plume contains three large-scale compositional heterogeneities and (2) all three heterogeneities extend into Kilauea’s melting region. However, the source region of Kilauea lavas must also be heterogeneous on a small scale to explain the rapid variations in the Pb, Sr, and Nd isotope ratios of the lavas. The fourth component appears to be common to all three of the active Hawaiian volcanoes, and thus, might represent the plume matrix. The Uwekahuna Bluff lavas also reveal a systematic temporal excursion in ratios of highly over moderately incompatible trace elements (e.g., Nb/Y) towards the lowest values yet observed at Kilauea. These low Nb/Y ratios (which correlate with the low 206Pb/204Pb ratios) are thought to result from relatively high degrees of partial melting of the plume matrix. Based on a correlation between high inferred degrees of partial melting and high eruption rates historically at Kilauea, the low Nb/Y ratios of the Uwekahuna Bluff lavas suggest that the eruption rate at Kilauea’s summit may have been unusually high in recent prehistoric times.

Thesis Defense - Spring 2009 - Peter Winther

2009-05-07T22:11:00.000-07:00

Magnetotelluric Investigation of the Santo Domingo Basin, Rio Grande Rift, New Mexico

Peter Winther
M.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Dr. George Jiracek

Wednesday, May 13th, 2008
CSL 422, 10:00am

http://www.scivee.tv/node/11176

ABSTRACT
Magnetotelluric (MT) investigations of the Santo Domingo Basin were made in 2000-2007 to assess the deep stratigraphy and tectonics of an intra rift basin. The studies were conducted during the SAGE (Summer of Applied Geophysical Experience) program to provide ‘hands-on’ learning experiences for students and to evaluate the local hydrologic regime. Most MT soundings were accomplished using Quantec Geoscience’s Titan 24 MT system. The Titan system is a distributed array MT instrument that allows the collection of up to 24 MT soundings simultaneously with a station spacing of 100 m. Sixty-five Titan MT soundings were collected along a 6.4 km-long profile where a petroleum exploration seismic survey was recorded during the 1970’s. The MT data were modeled using a smooth, two-dimensional (2-D) inversion code developed by Geosystem, Inc. Modeled resistivity values vary from 2-1000 ohm-m in the 2 - 4.5 km-thick sedimentary section. Resistivities exceed 1000 ohm-m in the basement interpreted to underlie the sediments. The sedimentary sequence indicates three distinct regimes: (1) an upper, unsaturated and freshwater saturated, basin-fill that ranges from 350 - 800 m-deep with resistivities of 8 - 85 ohm-m, (2) a deeper, mostly conductive region with higher brine and/or clay concentrations approximately 3 km thick with resistivities varying between 2 - 100 ohm-m and (3) a resistive sedimentary cover over the crystalline basement that ranges from 100 - 1000 ohm-m. Tectonic interpretations of the 2-D MT inversion profile indicate the locations of several buried, unmapped faults within the basin which agree with recent U. S. Geological Survey aeromagnetic interpretations. A geologic structure model for the area includes two grabens with the western graben down dropped with respect to the western graben.

Thesis Defense - Spring 2009 - Matthew Sisk

2009-05-07T15:23:00.000-07:00

Chemical and Physical Characteristics of Pulverized Tejon Lookout Granite Adjacent to the San Andreas and Garlock Faults: Implications for Earthquake Physics

Matthew Sisk
M.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Dr. Thomas Rockwell
Friday, May 8th, 2008
CSL 422, 3:00pm

ABSTRACT
We present new detailed analysis of pulverized Tejon Lookout granite from sections adjacent to the San Andreas and Garlock faults in southern California. The granite is pulverized in all exposures within about 100 m from both faults. Chemical analyses indicate essentially no or little weathering in the bulk of the rock, although XRD analysis shows the presence of smectite. Illite, and minor kaolinite in the clay-size fraction. Weathering products may dominate in the less than 1 micron fraction. The average grain size in all samples of pulverized granite range between about 26 and 208 microns (silt to fine sand), with the size distribution in part a function of proximity to the primary slip zone. The San Andreas fault samples are generally finer than those collected from adjacent to the Garlock fault. The particle size distribution for each sample follows a pseudo power law with a continuously changing exponent, which suggests that pulverization is not simply a consequence of direct shear. This average particle size is quite coarser than previous reports, which we attribute to possible measurement errors in prior work. Our data and observations suggest that dynamic fracturing in the wall rock of these two major faults only accounts for about 1% or less of the earthquake energy budget.

WEBINAR - Shawn Wright

2009-05-07T09:12:00.001-07:00

TIR spectroscopy of shocked Deccan basalt: Implications for Mars and Martian meteorites

Shawn Wright
Institute of Meteoritics
Department of Earth and Planetary Sciences
University of New Mexico

http://www.scivee.tv/node/11069
Hundreds of thousands of impact craters dominate the surfaces of the Moon, Mercury, and Mars. There exists much geomorphic and spectral evidence for basalt on those surfaces, so basaltic target rocks are most likely common. However, little work has been done on the thermal infrared (TIR) spectroscopy of shocked basalt metamorphosed by meteorite impact. This will have a direct application to the large amount of TIR data currently being returned from Mars orbiters and Rovers. The relationship between these TIR data collected remotely and laboratory data of samples is of much interest given that our only samples of Mars are shocked basalts. Results of research involving field work and samples from Lonar Crater, India, the only known terrestrial impact site emplaced in basalt, are described. The Deccan “Traps” flood basalts have been labeled as an excellent compositional and spectral analog for plagioclase-rich basalt on Mars identified from various orbiter and Rover instruments. Petrography provides details on the approximate range of shock pressure each class of shocked basalt has been subjected to, and field work has yielded an “ejecta stratigraphy” that displays where each class of shocked basalt is located. A comparison of the TIR spectroscopy of the unshocked Deccan basalt to its shocked equivalent aids in quantifying the changes due to shock. An application of this research has provided constraints on possible source craters/regions of certain shergottite meteorites, the shocked basalts from Mars.

Thesis Defense - Spring 2009 - Kean Bliss

2009-05-06T15:15:00.000-07:00

Evaluation of XRD and Raman peak broadening in shock-metamorphosed carbonates from selected carbonate-target bolide impact structures

Kean Bliss
M.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Dr. Jared Morrow

Wednesday, May 13th, 2008
CSL 422, 2:30pm

http://www.scivee.tv/node/11187

ABSTRACT
Identification of shock metamorphism in minerals is an important line of evidence for confirming the origin of potential impact-generated structures and associated deposits. Unlike common quartz and feldspar occurring in crystalline target rocks, shock-metamorphosed carbonates are not readily identified petrographically. Studies have indicated that X-ray diffraction (XRD) and micro-Raman spectrometry (MRS) peak broadening is a reliable indicator of shock metamorphism in carbonates. Samples from seven confirmed carbonate-target impact structures and other high temperature-pressure regimes (i.e., carbonatite, marble, and fault breccia) were analyzed in order to determine whether peak broadening is unique to impact structures. In addition, the MRS method is further tested for comparability to XRD analyses, and for the effects of different sample preparation (i.e., thin section vs. powder).
XRD analyses reveal that microstructural effects (i.e., crystallite size and lattice strain) contributing to peak broadening in potentially shocked samples follow expected trends of decreased crystallite size and increased lattice strain. However, fault breccias and carbonatites show microstructural effects comparable to those recorded for shocked samples, indicating that peak broadening is not unique to impact-related deposits.
Although XRD and MRS sample trends are similar, machine-derived and sample-derived variability is high in MRS analyses, contributing to uncertainty and less accurate peak width measurements. Large discrepancies exist between thin section and powder MRS analyses of identical samples. Estimated peak shock pressures calculated from previously established calibration lines for dolomite are much higher than expected; indicating that calibration curves should be specific to each impact structure and sample preparation protocol.

Thesis Defense - Spring 2009 - Emily Allen

2009-05-06T15:13:00.000-07:00

Physical and Chemical Characteristics of Unweathered Pulverized Rock along the San Andreas Fault, Little Rock, CA

Emily Allen
M.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Dr. Tom Rockwell
Wednesday, May 13th, 2008
CSL 422, 1:00pm

http://www.scivee.tv/node/11184

ABSTRACT
We present new observations on pulverized granitic rocks recovered from a shallow core adjacent to the San Andreas fault near Little Rock Creek. The site is characterized by extensive outcrops of granitic rocks with varying degrees of damage, at distances of up to a few hundreds of meters from the fault’s primary active strand. We used an auger drill-rig to recover a continuous core of pulverized rock to a depth of 42 meters. The core is composed mainly of pulverized Si-rich, Si-intermediate, and Si-poor granitoids. It crosses through several high clay content gouge zones, which correspond to secondary fault cores. Detailed results of particle size distribution (PSD) measured using a laser particle analyzer and standard sieving and pipette methods indicate that medium to coarse silt and fine sand (50-600 microns) are the dominant particle sizes for pulverized Si-rich granitoids recovered in the core. Very little clay size particles were observed in both surface and depth samples. Si-rich granitoid samples are comprised only of quartz, feldspar, white mica, and minor biotite with no pedogenic clay. Geochemical data indicate little if any chemical weathering. We conclude that the signature of pulverization results in shattering to silt and sand sized particles with essentially no component of weathering, which is similar to but slightly coarser than prior studies that were conducted on near surface samples at Tejon Pass and along the Garlock fault where a minor weathering component was observed.

Thesis Defense - Spring 2009 - Frank Forcino

2009-05-06T15:02:00.000-07:00

Mytilus californianus as an environmental monitor: a case study from central California

Frank Forcino
M.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Dr. Stephen Schellenberg

Wednesday, May 13th, 2008
CSL 422, 10:45am

http://www.scivee.tv/node/11178

ABSTRACT
Intraskeletal oxygen stable-isotope ratios (δ18O) and minor element ratios (Mg/Ca) were examined in modern Mytilus californianus specimens to test the hypothesis that these variables record ambient seawater temperature, and therefore can be measured in fossil specimens as a means of reconstructing paleotemperature. Specimens representing a range of ontogenetic stages and two extreme intertidal positions were collected monthly for one year from Santa Cruz, CA. While general linear modeling (GLM) of various monitored environmental parameters revealed temperature as the primary explanatory variable, the best goodness-of-fit GLMs for δ18O and Mg/Ca explained only 37.1% and 28.5% of variation, respectively, with additional significant variance attributable to intertidal positions and specimen size. Thus, M. californianus appears to be an unreliable means to reconstruct paleotemperature given the large amount of unexplained variation in intraskeletal δ18O and Mg/Ca and the role of variables effectively unknowable in the fossil record (e.g., intertidal position). In addition, a proxy species of interest cannot be assumed to be a comparable indicator of environmental conditions to similar species in the same genera or that share ecological characteristics."

SEMINAR - Shawn Wright

2009-04-30T15:23:00.000-07:00

TIR spectroscopy of shocked Deccan basalt: Implications for Mars and Martian meteorites

Shawn Wright
Institute of Meteoritics
Department of Earth and Planetary Sciences
University of New Mexico

May 6th, 2009

Hundreds of thousands of impact craters dominate the surfaces of the Moon, Mercury, and Mars. There exists much geomorphic and spectral evidence for basalt on those surfaces, so basaltic target rocks are most likely common. However, little work has been done on the thermal infrared (TIR) spectroscopy of shocked basalt metamorphosed by meteorite impact. This will have a direct application to the large amount of TIR data currently being returned from Mars orbiters and Rovers. The relationship between these TIR data collected remotely and laboratory data of samples is of much interest given that our only samples of Mars are shocked basalts. Results of research involving field work and samples from Lonar Crater, India, the only known terrestrial impact site emplaced in basalt, are described. The Deccan “Traps” flood basalts have been labeled as an excellent compositional and spectral analog for plagioclase-rich basalt on Mars identified from various orbiter and Rover instruments. Petrography provides details on the approximate range of shock pressure each class of shocked basalt has been subjected to, and field work has yielded an “ejecta stratigraphy” that displays where each class of shocked basalt is located. A comparison of the TIR spectroscopy of the unshocked Deccan basalt to its shocked equivalent aids in quantifying the changes due to shock. An application of this research has provided constraints on possible source craters/regions of certain shergottite meteorites, the shocked basalts from Mars.

http://www.scivee.tv/node/11069

WEBINAR - Elizabeth Cochran

2009-04-30T15:03:00.000-07:00

Imaging Fault Damage Zones with Seismic and Geodetic Data

Elizabeth Cochran
Department of Earth Sciences
University of California, Riverside

During earthquakes slip is often localized on preexisting faults, but it is not well understood how the structure of crustal faults may contribute to slip localization and energetics. Growing evidence suggests that the crust along active faults suffers anomalous strain and damage during large quakes. Data collected along several faults including the Hector Mine rupture, San Andreas Fault at Parkfield, and the Calico Fault show damage zones extending from 100 m to 1 km around the active slip plane. Recent seismic and geodetic data from the Calico fault in the eastern California shear zone reveal a wide zone of reduced seismic velocities and effective elastic moduli. Using seismic travel times, trapped waves, and interferometric Synthetic Aperture Radar observations, we document seismic velocities reduced by 40 - 50% and shear moduli reduced by 65% compared to wallrock in a 1.5-km-wide zone along the Calico fault. Observed velocity reductions likely represent the cumulative mechanical damage from past earthquake ruptures, but can sustain further damage in successive events These findings indicate that faults can affect rock properties at substantial distances from primary fault slip surfaces, and throughout much of the seismogenic zone, a result with implications for the portion of energy expended during rupture to drive cracking and yielding of rock and development of fault systems.

Graduate Student Highlight - Dale Burns

2009-04-23T16:13:00.001-07:00

Dale Burns
Volcanology

From a very young age I began to develop a fascination with earth science. In particular, I was intrigued by natural disasters. As I grew older my fascination continued to grow, and after taking a geology class in high school I decided that I would pursue a career studying volcanoes. After graduating high school, I received a B.A. in geology from Humboldt State University, and the following year I came to San Diego State University to work with Dr. Aaron Pietruszka. I have been very lucky throughout my student career and have been able to study various aspects of igneous petrology/volcanology, from experimental petrology and isotope geochemistry to mapping a variety of volcanic terrains. While studying at SDSU, I have had the fortunate opportunity to present my data at multiple scientific conferences, including an oral presentation at the 2008 IAVCEI in Reykjavik, Iceland. I will be graduating this spring (2009) with an M.S. in Geological Sciences, and will be starting my Ph.D. next year at Oregon State University.

Advisor Aaron Pietruszka

Thesis The Recent Prehistoric Geochemical Evolution of Summit Lavas From Kilauea Volcano, Hawaii

In the most general sense, I use isotope ratios along with major and trace element abundances to investigate changes in the composition of what is melting beneath Kilauea Volcano, and how these changes relate to eruption rates in the recent prehistoric times.
Research Interests Volcanology, caldera complexes, hydrovolcanic features, isotope geochemistry, general geochemistry, mantle plumes, ignimbrites, and pretty much everything else associated with explosive volcanic eruptions.

Education

Ph.D. Geosciences (starting Fall 2009) Oregon State University, Corvallis, Oregon
M.S. Geological Sciences (2009) San Diego State University, San Diego, California
B.A. Geology (2007) Humboldt State University, Arcata, California

SEMINAR - Elizabeth Cochran

2009-04-23T14:29:00.000-07:00

Imaging Fault Damage Zones with Seismic and Geodetic Data

Elizabeth Cochran
Department of Earth Sciences
University of California, Riverside

April 29th, 2009

During earthquakes slip is often localized on preexisting faults, but it is not well understood how the structure of crustal faults may contribute to slip localization and energetics. Growing evidence suggests that the crust along active faults suffers anomalous strain and damage during large quakes. Data collected along several faults including the Hector Mine rupture, San Andreas Fault at Parkfield, and the Calico Fault show damage zones extending from 100 m to 1 km around the active slip plane. Recent seismic and geodetic data from the Calico fault in the eastern California shear zone reveal a wide zone of reduced seismic velocities and effective elastic moduli. Using seismic travel times, trapped waves, and interferometric Synthetic Aperture Radar observations, we document seismic velocities reduced by 40 - 50% and shear moduli reduced by 65% compared to wallrock in a 1.5-km-wide zone along the Calico fault. Observed velocity reductions likely represent the cumulative mechanical damage from past earthquake ruptures, but can sustain further damage in successive events These findings indicate that faults can affect rock properties at substantial distances from primary fault slip surfaces, and throughout much of the seismogenic zone, a result with implications for the portion of energy expended during rupture to drive cracking and yielding of rock and development of fault systems.

WEBINAR - Brandon Browne

2009-04-23T14:13:00.000-07:00

Not-So-Simple Cinder Cone Plumbing Systems: Examples From the Sierra Nevada

Brandon Browne
Department of Geological Sciences
California State University Fullerton

Cinder cones situated in continental monogenetic volcanic fields are generally thought to erupt single magma batches over short periods of time. However, field mapping efforts combined with petrologic, geochemical, and thermobarometric analysis of erupted products from two unrelated volcanic fields in California (Red Cones, 5 km SW of Mammoth Mountain; and Golden Trout, 5 km SW of Mt Whitney) indicate pronounced differences in the eruption volumes and Pressure-Temperature crystallization histories of erupted basalts despite overall similarities in magma source. These findings suggest that magma plumbing systems and the mechanisms for magma supply at cinder cones are actually quite complex, and therefore require us to modify our perspectives on how they from as well as the types of geophysical signals they potentially yield before, during, and after eruptions.

WEBINAR - David T King Jr

2009-04-23T11:02:00.000-07:00

The Cretaceous-Paleogene ("KT") Boundary In Belize and Alabama

David T. King, Jr.
Department of Geology and Geography
Auburn University, Alabama

Belize - At Albion Island in northern Belize, Cretaceous-Paleogene (KT) boundary deposits, also known as the Albion formation, rest upon karsted and fractured Maastrichtian dolostones. These deposits consist of a basal impactoclastic clay layer (~ 1 to 2-m thick) and an upper carbonate-rich, coarse impactoclastic breccia layer (up to 15-m thick). The focus of this paper is the upper layer, the Albion impactoclastic breccia. The Albion impactoclastic breccia shows several important sedimentary structures, including development of discrete sedimentation units (2 to 7-m thick), which are strata that have been enhanced by horizontal shearing, and other sedimentary structures such as normal and reverse size grading, clast imbrication, flow lamination, and isolated and linked aggregates of clasts (i.e., clast clustering).
Most carbonate clasts within the coarse impactoclastic unit show a broad range of angularities and shapes, with the most common being subangular and compact-bladed to compact-elongated, respectively. Surface texture analysis of carbonate clasts shows several types of surface markings, which display a gross sequential order (i.e., facets, polish, striations, cryptographic markings, bruises and pits, and chips). In-situ, apparent-diameter measurements of the carbonate clasts, which ranged in size from 10 to 300 mm (or -3.3 to -8.2 Ø);, resulted in cumulative grain-size (Ø) frequency curves with similar shapes through the interval –3.3 Ø and –6.25 Ø (i.e., 10 to 76 mm). Matrix, the total area comprised of less-than-10 mm (< -3.3 Ø) particles, ranged from approximately 71 to 82 percent. Modified moment measures of these curves show these breccias are “extremely poorly sorted.” The matrix content increase upward through the entire coarse impactoclastic layer, but is slightly lower near its top. The Albion impactoclastic breccia has sedimentary structures and sedimentologic characteristics suggesting its mode of emplacement during the impact aftermath was similar to that of a very large volcanic debris avalanche. Sedimentation units show evidence of early turbulent flow and a more conspicuous later stage of laminar flow with shearing accompanying emplacement of most breccia sedimentation units. Clasts within these debris flows are not locally derived for the most part. We speculate that each sedimentation unit at Albion may represent a separate emplacement event during the process of ejecta curtain collapse, perhaps owing to variations in atmospheric interaction with the debris. Alabama - At Shell Creek stratigraphic section, Wilcox County, Alabama, a < 1 m-thick, Cretaceous-Paleogene boundary sand body crops out over an area of ~ 200 m2. This sand body consists of (1) a basal impact spherule-bearing, coarse to medium sand and (2) an overlying fine sand with hummocky-type cross-lamination. This K-T boundary sand body probably represents post-impact, shelf sedimentation events involving (1) gravity-driven resedimentation of reworked impact spherule-bearing sands and (2) energetic wave reworking of the impart spherule-bearing, gravity-driven deposits or other subsequently deposited sands. Most impact spherules from Shell Creek are spherically shaped grains (~ 1 mm in diameter) that are now hollow, or were hollow prior to secondary calcite filling. Most impact spherules from Shell Creek consist of an outer shell, which is composed of smectitic clays, and an inner region of open space or sparry calcite. Most of these impact spherules still retain features like vesicles that attest to their former molten condition. This stratigraphic section is remarkable in that it represents the most easterly U.S. Gulf Coastal Plain occurrence of abundant impact spherules in a Cretaceous-Tertiary (K-T) boundary sand body.

SEMINAR - Brandon Browne

2009-04-18T08:45:00.000-07:00

Not-So-Simple Cinder Cone Plumbing Systems: Examples From the Sierra Nevada

Brandon Browne
Department of Geological Sciences
California State University Fullerton

April 22nd, 2009

Cinder cones situated in continental monogenetic volcanic fields are generally thought to erupt single magma batches over short periods of time. However, field mapping efforts combined with petrologic, geochemical, and thermobarometric analysis of erupted products from two unrelated volcanic fields in California (Red Cones, 5 km SW of Mammoth Mountain; and Golden Trout, 5 km SW of Mt Whitney) indicate pronounced differences in the eruption volumes and Pressure-Temperature crystallization histories of erupted basalts despite overall similarities in magma source. These findings suggest that magma plumbing systems and the mechanisms for magma supply at cinder cones are actually quite complex, and therefore require us to modify our perspectives on how they from as well as the types of geophysical signals they potentially yield before, during, and after eruptions.

SEMINAR - Jill Pearse

2009-04-13T15:21:00.000-07:00

Post-rifting deformation in Afar, Ethiopia, following the 2005 intrusion event

Jill Pearse
Scripps Institution of Oceanography
University of California, San Diego

April 15th, 2009

The 300-km wide Afar depression is located at the junction between the Red Sea, Gulf of Aden and East African rifts. In September and October of 2005, a series of large earthquakes and a volcanic eruption signaled the intrusion of a dike along the Dabbahu magmatic segment (in the Red Sea arm) of the Afar rift. Results of elastic modeling constrained by InSAR (Wright et al 2006) data suggest that the 60-km long segment opened by up to 8 m, between depths of 2-9 km. Relaxation of stresses in the crust below the brittle-ductile transition following the intrusion event should create geodetically observable surface deformation, however this signal can be obscured by continuing active intrusions. Using 3-D finite element models, we predict the surface deformation following the 2005 Dabbahu event for a range of crustal and mantle rheologies. We compare our model results to InSAR data spanning the 3 years since the intrusion to quantify the post-rifting deformation and place constraints on the rheology below the brittle-ductile transition in Afar.

Pacific Section Imperial Barrel Winners

2009-04-08T10:17:00.000-07:00

The SDSU team wins, for the second years in a row, the Pacific Section AAPG’s Imperial Barrel Award Program (IBA). Accolades include a prize of $1500 and a chance to compete in the IBA finals. Finals are June 5th and 6th in Denver Colorado against national and international competition.

Team members are: John Abeid, Leslie Clayton, Byrant Fulk, Christopher Kohel, and Peter Winther.

NEW SOFTWARE - Midland Valley 3DMove

2009-04-07T10:47:00.000-07:00

The Department of Geological Sciences has been awarded seven licenses for the Midland Valley software 3DMove. 3DMove is the world’s leading 3D software tool for structural restoration, validation and analysis. 3dMove uses the principles of structural geology to help build models where little data exists, and to use the geological evolution of the model to define parameters for further analysis.

The unique advantage of 3DMove, when compared with other model building software, is that it takes into account geological time. Build valid models and analyse your ideas about how the structure developed through geological time with present day & past time steps providing both qualitative & quantitative analysis.The unique advantage of 3DMove, when compared with other model building software, is that it takes into account geological time. Build valid models and analyse your ideas about how the structure developed through geological time with present day & past time steps providing both qualitative & quantitative analysis.

One of the many ways this software will be used is teach students techniques to create more accurate models, reducing risk and improve productivity of gas and oil exploration/production.

3DMove brochure

WEBINAR - Greg Hirth

2009-03-26T10:51:00.000-07:00

Understanding earthquakes at the microscopic scale

David Bowman
Department of Geology and Geophysics
Woods Hole Oceanographic Institution

I will first review of how to relate rock strength determined from lab experiments to geological and geophysical observations - emphasizing apparent paradoxes and successes. I will then introduce why understanding earthquake mechanisms in the oceanic lithosphere can provide new insights into the rheological properties of fault zones, and present an experimental study on fault stability in which analysis of the micromechanics of friction provides justification for the extrapolation of the lab data to natural conditions. With this new insight, I will then return to the problem of relating the lab data to geophysical observations.

New Photos Online - Volcanology - Pinacate

2009-03-24T21:18:00.000-07:00

Volcanology - Pinacate

SEMINAR - Greg Hirth

2009-03-23T08:40:00.000-07:00

Understanding earthquakes at the microscopic scale

David Bowman
Department of Geology and Geophysics
Woods Hole Oceanographic Institution

March 25th, 2009

SDSU Science Sampler / San Diego Science Festival

2009-03-20T10:08:00.000-07:00

Free Fun Acticities for the Entire Family
MARCH 21st, 12-4pm

SEMINAR - David Bowman

2009-03-11T21:10:00.000-07:00

Accelerating Moment Release Before Large Earthquakes: Life and Death of an Earthquake Prediction Scheme

David Bowman
Department of Geological Sciences
California State University, Fullerton

Postponed

It has been suggested that large earthquakes are preceded by a systematic increase in the rate of background seismicity in a broad region around the impending event. This rate change, known as “accelerating moment release” (AMR), has been proposed as a precursory signal that could be used to forecast large earthquakes. Bowman and King [GRL, 2001] demonstrate that the pre-mainshock stress field, as indicated by a simple backslip model of the event, can be used to define the critical region that optimizes the precursory AMR signal. The observation of accelerating seismicity within this region represents a period of increased likelihood of a large earthquake. With sufficient knowledge of the regional tectonics, it should be possible to estimate the likelihood of earthquake rupture scenarios by searching for AMR related to stress accumulation on specific faults. This talk will present two algorithms that randomly search global plate boundaries for AMR signals before potential large events. Each plate boundary is searched for AMR using circular regions following the method of Bowman et al.[1998] and fault-based stress accumulation regions following the approach of Bowman and King [2001]. The fault-based algorithm uses a schematic model of the plate-boundary faults to represent potential sources; subduction zones are modeled as single mega-thrust faults, spreading centers as a normal faults, and transforms as single strike-slip faults. In each approach, the entire global plate boundary network is populated by potential sources and searched for precursory AMR. False-alarm and Failure-to-predict statistics are calculated based on historical seismicity; given the heterogeneity of modern instrumental catalogs, these statistics suggest that the current AMR algorithm does not provide significant predictive power.

The New AGS

2009-03-11T20:23:00.001-07:00

AGS (Associated Geology Students) has a new look and a new icon. Check out their new website:
http://www-rohan.sdsu.edu/~ags

Along with their new look AGS has taken on a name from the departments past, Tecton Delvers. The Tecton Delvers was the name of the geology club back in the 1960's.

New AGS Officers:

President: Zachary Hasten
Field of Study: Volcanology
Contact: zhasten1205@gmail.com

Vice President: Evan Martin
Field of Study: Paleontology
Contact: mooseprowler@netscape.net

Secretary: Karl Bloor
Field of Study: Geothermic Processes
Contact: ksbloor@yahoo.com

Treasurer: Heather O'brien
Field of Study: Hydrogeology
Contact: gigglemonsterpi@gmail.com

Representative: Erik Gordon
Field of Study: Hydrogeology
Contact: liljimmy_101@yahoo.com

2009 Alumni Banquet

2009-03-11T10:39:00.000-07:00

ANNUAL ALUMNI BANQUET
APRIL 24, 2009

This year's banquet will be held at Tom Ham's Lighthouse on Harbor Island in San Diego. The Friday evening event begins with a social hour at 6pm and dinner at 7pm. The meal will be followed by a program, including a "roast" of this year's recipients of the Baylor Brooks Honored Alumni Award. The two honorees being recognized this year are engineering geologists, Dorian Kuper and Tom Kuper. If you want to contribute a short, silly tale or possibly participate in the roast, let Sue know.

The "Bay Buffet" dinner will include caesar salad, potato salad, fresh seasonal fruit, Tuscan penne pasta, Vercruz mahi mahi, carved turkey, rice, seasonal mixed vegetables and dessert! Beverages will be available for purchase from an in-room, cash bar.

As a fund-raiser to partially fund students' banquet meals and other Alumni Association activities, we will have a silent auction that will be set up at the beginning of the evening and will conclude after the evening's program. If you have any items to donate to the auction, please bring them We sincerely appreciate your donations!

For banquet reservations, please complete and mail in the linked form below by April 17th.

CURRENT SDSU GEO-STUDENTS - At least 50 percent of your banquet fee will be reimbursed IF you make a reservation by the deadline AND show up at the banquet!!! And, remember, SDSU geo-alumni may be your future employers and are a great bunch of people to know! You're gonna be one of them!

Tom Ham’s Lighthouse
2150 Harbor Island Drive
San Diego, CA 92101
619-291-9110
Directions

For More Information :
Contact Sue - 619-442-8022.

Banquet Reservation Form

Gary Girty Awarded the President's Top 25 Award

2009-03-10T08:44:00.000-07:00

Thirteen years ago, San Diego State President Stephen L. Weber and his wife Susan began the "Top 25 Awards" at SDSU to celebrate the extraordinary contributions of faculty, staff, students, alumni, and community members.

This year one of the recipients of this prestigious award is Dr. Gary H. Girty from the Department of Geological Sciences. Gary is honored because of his work with the general education course Planet Earth (Geol100). One of his major accomplishments with this blended online/lecture based course is the digital textbook written by Gary. It contains many interactive illustrations, an online syllabus containing specific learning outcomes goals, a set of practice exams (study guides), and video lectures (screencasts) covering material in each of the 13 chapters covered during the semester.

Girty joined the department in 1984. Since then he has supervised the successful completion of 61 M.S. and 79 B.S. theses, and has published 67 papers, books, and guidebooks, and over 76 abstracts the vast majority of them with student co-authors. He was selected for the San Diego State University Senate Excellence In Teaching Award – Recognizing Excellence As A Teacher-Scholar for 2006-2007. In 2002-2003 he was awarded the Outstanding Faculty and Staff Award by the Mortar Board at SDSU, and has been selected as the most influential professor by the department’s top graduating senior 7 times. He has served as the Vice-Chair (2005), Chair (2006), and Past-Chair (2007) of the Cordilleran Section, Geological Society of America. He is currently serving his 9th year as the Chair of the department.

Girty’s research program focuses on (1) understanding how plutonic rock weathers, (2) how fault zone architecture develops, and (2) the tectonic development of the SW Cordillera. Since 2002 he has received a total of $124,281 in external and internal funding, and has published 15 papers in journals and books and 13 abstracts all with student co-authors. He also was one of 6 editors on the GSA Special Paper 347 honoring the career of Gordon Gastil, and was one of 2 editors of the Pacific Section SEPM volume honoring the career of Patrick Abbott.

Thesis Defense Online! - Andrew Gritz

2009-03-09T21:46:00.000-07:00

Effect of Heterogeneous Prestress on Near-Field Rupture Directivity

Andrew Gritz
M.S. Candidate
Advisor Dr. Steven Day

ABSTRACT
To supplement the very limited number of strong motion recordings in areas near to earthquake sources, numerical modeling of the rupture process and radiated seismic energy was carried out to study such ground motion. The near fault region is susceptible to very strong shaking both because of proximity to the fault and directivity effects, but may also be sensitive to particulars of the rupture process including effects of heterogeneity on the coherence of the rupture. Stochastic realizations of initial stresses on the fault plane with varying values of roughness, combined with a depth-dependent normal stress, are used in numerical simulations of large strike-slip earthquakes to examine how such heterogeneities influence the near-field directivity effects. The resulting synthetic earthquakes have predominantly unilateral rupture propagation with varying degrees of rupture coherence. Response spectra of the synthetic acceleration records at the free surface are analyzed by a method analogous to that used to develop empirical ground motion relations. The dependence of the response spectral shapes on hypocentral distance reflects, in some cases, a roughly self-similar initial rupture growth. The result is complex behavior of response spectral amplitude as a function of along-strike distance at smaller periods, but clearer directivity (along-strike enhancement) at periods of 2 seconds and above. Also present in many cases is a saturation in the trend of along-strike enhancement of the response spectra values when hypocentral distance exceeds some threshold. At periods of 2 seconds and larger, results of an analysis of directivity match reasonably well with earlier empirical studies, while at a period of 1 second, little directivity is observed, in agreement with recent empirical predictions. The stochastic heterogeneities have mixed effects on directivity, but at larger periods there is systematic increase in directivity effects with increasing roughness. However, more important than this heterogeneity, appears to be the underlying depth dependence of the normal stress. To quantify the observed saturation in directivity effects, data from the simulations is fit to a model capping such effects, and values of the predictor value at which this saturation occurs generally agree with empirical and numerical predictions for large strike-slip faults. The value of the predictor variable at which this saturation occurs, changes when the fault length is extended, and an alternative predictor variable is much better able to track this saturation.

SEMINAR - PetroAzteca

2009-03-08T19:09:00.000-07:00

Technical Assessment of the Barents Sea Petroleum Potential

2009 Imperial Barrel Team
John Abeid, Lelsie Clayton,
Bryant Falk, Chris Kohel
and Peter Winther
Department of Geological Sciences
San Diego State University

Wednesday, March 11th, 2009

AAPG’s Imperial Barrel Award Program (IBA) is an annual prospect/exploration evaluation competition/presentation competition between university student teams competing to win scholarship funds dedicated to petroleum geoscience education created for geoscience graduate students. The program is rigorous and contributes to AAPG’s mission of promoting petroleum geoscience training and advancing the careers of geoscience students.

This is a global competition, where the University teams analyze a complete dataset in six to eight weeks prior to the competition and (geology, geophysics, land, economics, production infrastructure, and other relevant materials). Each team delivers their results in a 30-minute presentation to a panel of industry experts.

Students gain experience using real technology on a real dataset. Additionally, students benefit from the feedback from the industry panel, the opportunity to impress potential employers in the audience, and the chance to win cash prizes for their schools, who will select the winning team on the basis of technical quality, clarity and originality.

The IBA is a hands-on opportunity for students to experience the creative process and the high-tech science that is the foundation of the Energy Industry today.

SDSU were the 2008 AAPG Imperial Barrel Pacific Section Champions

New Photos Online - Alumni Field Trip

2009-03-05T12:25:00.001-08:00

2009 Annual Alumni Field Trip

The 23rd Annual SDSU Geology Field Trip/Campout was at the Picacho State Recreation Area, California, about 25 miles north of Winterhaven, CA. Jon Sainsbury, who is completing his Master's Thesis in the area, graciously agreed to be the 2009 Field Trip Leader. His work involves mapping an anticlinorium that has been re-activated by strike-slip faulting. By correlating age dates for the Black Mountain Basalt and the Quechan volcanics, which are incorporated into the Bear Canyon conglomerate, evidence for much younger folding than previously interpreted has been inferred. The area also contains the Chocolate Mountains and Gatuna Fault which are detachment faults. These are offset by numerous San Andreas related strike slip faulting in the Eastern California Shear Zone. Some of these faults have displacements of near 0.5 km. These detachment faults separate the Orocopia Shist, a basement gneiss and the Winterhaven Formation.
The Field Trip started from the "Group Campground" at 10:00 AM on Saturday February 28th, 2009.

DIRECTIONS: From SDSU take 1-8 eastbound for 172 miles to the 4th Ave/Winterhaven exit (about 3 hours non-stop for timing purposes.) Make a left turn at the stop sign off the freeway ramp and go about ½ mile to next stop sign. Make right turn onto S-24, cross the canal and in about 300 feet make a left turn staying on S-24. Follow S-24 and the signs towards Picacho SRA. Several miles up the road S-24/Ross Rd. will turn to the right but you will go straight for another 6 miles until the pavement ends. You will follow the main gravel road across the canal and in 18 miles you will reach the campground. Watch for the group camp sign directing you to the left, it is several hundred feet past the park check in stop. GPS coordinates are N 33-01-11.5, W 114-36-58.6. The AAA Colorado River Guide Map (best) and the AAA Imperial County Map (good) both have the roads delineated well for finding the Campground.

Thesis Defense - Spring 2009 - Andrew Gritz

2009-03-03T14:26:00.000-08:00

Effect of Heterogeneous Prestress on Near-Field Rupture Directivity

Andrew Gritz
M.S. Candidate
Advisor Dr. Steven Day
Monday, March 9th, 2008 CSL 422, 11:00am

ABSTRACT
To supplement the very limited number of strong motion recordings in areas near to earthquake sources, numerical modeling of the rupture process and radiated seismic energy was carried out to study such ground motion. The near fault region is susceptible to very strong shaking both because of proximity to the fault and directivity effects, but may also be sensitive to particulars of the rupture process including effects of heterogeneity on the coherence of the rupture. Stochastic realizations of initial stresses on the fault plane with varying values of roughness, combined with a depth-dependent normal stress, are used in numerical simulations of large strike-slip earthquakes to examine how such heterogeneities influence the near-field directivity effects. The resulting synthetic earthquakes have predominantly unilateral rupture propagation with varying degrees of rupture coherence. Response spectra of the synthetic acceleration records at the free surface are analyzed by a method analogous to that used to develop empirical ground motion relations. The dependence of the response spectral shapes on hypocentral distance reflects, in some cases, a roughly self-similar initial rupture growth. The result is complex behavior of response spectral amplitude as a function of along-strike distance at smaller periods, but clearer directivity (along-strike enhancement) at periods of 2 seconds and above. Also present in many cases is a saturation in the trend of along-strike enhancement of the response spectra values when hypocentral distance exceeds some threshold. At periods of 2 seconds and larger, results of an analysis of directivity match reasonably well with earlier empirical studies, while at a period of 1 second, little directivity is observed, in agreement with recent empirical predictions. The stochastic heterogeneities have mixed effects on directivity, but at larger periods there is systematic increase in directivity effects with increasing roughness. However, more important than this heterogeneity, appears to be the underlying depth dependence of the normal stress. To quantify the observed saturation in directivity effects, data from the simulations is fit to a model capping such effects, and values of the predictor value at which this saturation occurs generally agree with empirical and numerical predictions for large strike-slip faults. The value of the predictor variable at which this saturation occurs, changes when the fault length is extended, and an alternative predictor variable is much better able to track this saturation.

Magma mix-up

2009-02-20T14:52:00.000-08:00

Basalts from the Snake River Plain (pictured above) in Yellowstone National Park in the northern United States look like they originate from deep in Earth’s mantle. But they have the characteristic isotopic signature of rocks from shallower reaches — from the continental lithosphere. This curiosity has been explained by Barry Hanan of San Diego State University, California, and his colleagues. Using mass spectrometry on samples of volcanic rock, the authors showed that deep-mantle magma can inherit the lithosphere’s isotopic signature when it rises and picks up contamination. The findings warn geologists about assuming too much from isotopic signatures.

Source: Nature, Vol 45618/25 December 2008

Reference: Geology 36, 51–54 (2008)

WEBINAR - Kathleen R. Johnson

2009-02-19T11:57:00.000-08:00

Reconstructing Asian Monsoon History from Chinese Speleothems

Kathleen R. Johnson
Department of Earth System Science
University of California, Irvine

While we know that modern anthropogenic climate change is superimposed upon significant natural climate variability, the instrumental record of climate is too short to capture the full range of this variability. In order to fully understand and predict future changes, therefore, high-resolution, welldated paleoclimate records are needed to extend the record. This paleoclimate data allows us to quantify natural variability and learn how the climate system responded to past changes in boundary conditions and forcings and provides a vital test for state-of-the-art coupled climate models. Cave calcite deposits (speleothems) are widely studied paleoclimate archives that have led to significantly improved records of past climate variability over a wide range of timescales (seasonal to glacialinterglacial), most notably in low-latitude and monsoon regions. Speleothems are well-suited for terrestrial climate reconstruction because: they tend to be very pure and well-preserved; they usually contain clear visible growth banding which, like tree rings, is often annual in nature; they can be very precisely dated using uranium-series radiometric dating methods; and they contain numerous types of physical and geochemical proxy data. In this lecture, I will present an introduction to speleothem based paleoclimate proxies and describe ongoing modern calibration studies we are conducting at Heshang Cave, China to test and develop new seasonal resolution proxies of Asian monsoon rainfall. In addition, I will present multiple records of Asian monsoon rainfall obtained from stable isotope and trace element variations in Chinese speleothems and discuss the important role of the Asian monsoon in the global climate system.

WEBINAR - Jared Kluesner

2009-02-11T17:49:00.000-08:00

Geologic and Hydrologic Role of Sill Intrusion and Delineation of the Oceanic Crustal Boundary in the Central Gulf of California

Jared Kluesner
Marine Physical Laboratory
Scripps Institution of Oceanography

Geologic and Hydrologic Role of Sill Intrusion and Delineation of the Oceanic Crustal Boundary in the Central Gulf of California High-resolution multichannel profiles recently shot in the central Gulf of California display concordant and discordant (concave-upwards) sills intruded shallowly within (I) young sediments in the axial troughs of Guaymas, Carmen and Farallon Basins, (II) off-axis in the basin floors, and (III) within the sediment cover of subsided and extended continental crust. We interpret some imaged sills as 3D saucer-shaped intrusions based on their concave-upward profiles, the overlying circular and elliptical plans of domal uplifts of the present multibeam-mapped seafloor, and their striking resemblance to field-mapped and 3-D seismically imaged saucer-like sills. Vertical zones of high-amplitude, disturbed reflectors leading up from sills are probably "blow-out pipes" acting as conduits for hydrothermal fluids and gases migrating up and away from the heated sill-sediment contact aureole, forming pockmarks on the present seafloor. Bright spots, dim spots, phase reversals, and acoustic turbidity in the sediments above sill intrusions suggest the presence of hydrocarbons and fluid flow throughout the study area. Seismic evidence of sill intrusions into the shallow crust throughout the central gulf suggests melt is being delivered not just to spreading centers, but to a much broader area of oceanic and continental crust. We have improved the delineation of the oceanic/continental crustal boundary in the central and southern gulf by sampling igneous basement (tholeiitic basalt and gabbro = oceanic; granitic = continental), by identifying the extent of magnetic stripes diagnostic of seafloor spreading, by interpreting multichannel reflection profiles, and by geomorphology. Although the "boundary" is somewhat smeared by the intrusion of shallow sills (some known to be tholeiitic, most inferred to be) into the cover of both granitic and oceanic basement, we find no evidence of "transitional zones" of hybrid crust; at those sheared and rifted margins where basement is accessible, granite commonly abuts tholeiitic flows and sills. Seafloor spreading magnetic anomalies, with low amplitudes and broad transition widths, can be read out to C2Ar in Alarcon Basin, and C2An.1 in Guaymas Basin (but only on profiles that avoid major off-axis seamounts and intrusions); in both cases they indicate significantly slower accretion during the first 1 m.y. of spreading, presumably because of concurrent continued extension of the rifted margin. Widespread sill intrusion over continental basement does hamper identifying the ocean/continental boundary on seismic reflection profiles, and because the already thin Cordilleran crust was clearly highly extended during prolonged rifting we do not think that crustal thickness is a reliable criterion for the extent of oceanic crust.

Tsunami safety stressed

2009-02-06T11:34:00.000-08:00

Children's video puts focus on preparedness

Source San Diego Union Tribune
By Robert Krier
Union-Tribune Staff Writer

Students at Del Mar Heights Elementary School watched an animated DVD about tsunami preparedness yesterday. (Eduardo Contreras / Union-Tribune) - Online: For Robert Krier's Weather Watch blog, go to weatherwatch. uniontrib.com. To view the video “Tsunamis: Know What to Do!” go to readysandiego.org.
DEL MAR — Colorful crabs gave snappy, rhyming pointers for responding to a potential tsunami to second-and third-graders at Del Mar Heights Elementary School yesterday.
In a six-minute video, the animated characters sang, “If the count goes to 20 when an earthquake starts to shake, then we won't hesitate but instead evacuate.”
So sang the children – who also danced along with the crustaceans – during the premiere of the video, which the San Diego County Office of Emergency Services created with a $30,000 federal grant.
The trick for emergency-preparedness officials is getting the tsunami message out to everyone who needs to hear it. They know that most residents along San Diego's coast laugh at the idea of a tsunami smashing into their area.
But the county isn't free of tsunami risks. The waves are “very likely, but not very frequent,” said geologist Pat Abbott, a professor emeritus at San Diego State University.
The last time a tsunami caused damage in the region was in 1964, after a quake in Alaska sent waves that banged boats and piers on San Diego Bay.
More destructive tsunamis are possible, Abbott said.
“It may happen only once every several thousand years, but you never know when that last day is up,” he said.
The new video is part of a multiagency effort to spread the word: If you're at the beach or in a low-lying coastal area and you feel a prolonged earthquake, head at least one mile inland or to higher ground as soon as possible.
“We know from past experience that schoolchildren are very good conduits for information about hazards,” said Jim Goltz, manager of the California Emergency Management Agency's Earthquake and Tsunami Program.
Three children of county emergency-services workers – Claire Amabile, a student at Twin Peaks Middle School in Poway, and Del Mar Heights students Joseph and Esther Olsen – supplied some of the crabs' voices.
Jack O'Connell, the state's superintendent of public instruction, yesterday urged students throughout California to watch the video. Goltz hopes the footage of singing crabs also will be shown at state coastal parks and, eventually, in beach towns around the nation.
San Diego County's beach communities have been slow at becoming what the National Weather Service considers “tsunami ready.” The agency is responsible for preparing coastal cities for a tsunami.
Only Imperial Beach has earned the designation in this region, said Ed Clark, warning-coordination meteorologist for the weather service. In contrast, all of Orange County's seaside cities are tsunami-ready.
To qualify for the designation, cities must set up warning systems and communication links with the weather service, promote public readiness through education programs and develop a tsunami plan that includes emergency drills.
“There hasn't been the push here that there has been in Orange (County),” partly because of greater attention paid to major wildfires in San Diego County since 2003 and extra terrorism concerns related to the military's presence, Clark said.
San Diego County's shoreline is unlikely to suffer major damage from a tsunami generated by a distant quake, Abbott said. But underwater faults nearby are capable of unleashing a 7.0-magnitude quake that might cause undersea landslides, which could then send large waves toward the region's beaches.
“It's entirely reasonable to visualize a tsunami of 20 feet or higher” washing ashore at Mission Beach or other low-lying spots, Abbott said.

WEBINAR - Stephen T. Hasiotis

2009-02-05T17:48:00.000-08:00

Ichnology for the 21st Century: Understanding the differences between continental and marine trace fossils, with implications to the diversity, distribution, and evolution of soil biota

Stephen T. Hasiotis
Department of Geology
University of Kansas
Coeditor PALAIOS

The study of ichnology has come a long way since its inception and it continues to evolve. In particular, progress is being made in understanding the implications of trace fossils in the continental realm and how they can be used in conjunction with subdisciplines in geology to reconstruct the past. Organisms in all domains of life display behaviors that greatly expanded our definition of ichnology. Ichnology is the study of all organism behavior-not just animals. Accordingly, a trace fossil is the product of an organism interacting with a medium in an environment, which generates a three-dimensional physical structure-the resultant trace fossil can be micrometers to kilometers in scale. Though behaviors and resultant trace fossils may be similar morphologically in continental and marine settings, the organisms and behaviors that produced them and the physicochemical factors that controlled their distribution, depth, diversity, and abundance can be strikingly different. Ongoing research with modern terrestrial and aquatic organisms in the field and laboratory reveal the behaviors behind the production of burrow morphologies whose genesis and significance would otherwise be misinterpreted. The study of these modern traces, organisms, and their distribution allows us to recognize how their burrow morphologies and sedimentary associations record the environmental, ecologic, hydrologic, and climatic settings in which they are formed. Comparison of these modern structures and their tracemakers to trace fossils in continental deposits in the geologic record provide stronger clues about the implications of trace fossils for interpreting and reconstructing the sequence of events and conditions that produced those deposits. They also provide information on the evolution and radiation of organisms and ecosystems where the body fossil record is poor. As a result of these new research endeavors, trace fossils are being used to (1) extend the fossil record and understand the radiation of organisms, (2) interpret more accurately environments of deposition and the extent of pedogenesis that have modified those deposits, (3) contribute to understanding better the effects of climate change on biota, environments, and hydrologic systems, and (4) correlate significant surfaces in continental strata and identify subtle but significant shifts in physicochemical conditions and environments.

New Publication - Dr. Barry Hanan

2009-02-03T08:49:00.000-08:00

Geochemical stages at Jasper Seamount and the origin of intraplate volcanoes

Geochemical stages at Jasper Seamount and the origin of intraplate volcanoes
J. G. Konter
Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0225, USA

H. Staudigel
Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0225, USA

J. Blichert-Toft
Laboratoire des Sciences de la Terre, Ecole Normale Supérieure de Lyon, F-69364 Lyon CEDEX 7, France

B. B. Hanan
Department of Geological Sciences, San Diego State University, San Diego, California 92182-1020, USA

M. Polvé
Observatoire Midi-Pyrénées, Université Paul Sabatier, F-31400 Toulouse, France

G. R. Davies
Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, Netherlands

N. Shimizu
Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543-1541, USA

P. Schiffman
Department of Geology, University of California, Davis, California 95616, USA

Ocean intraplate volcanoes (OIVs) are formed in a sequence of stages, from large to small, that involve a systematic progression in mantle melting in terms of volumes and melt fractions with concomitant distinct mantle source signatures. The Hawaiian volcanoes are the best-known example of this type of evolution, even though they are extraordinarily large. We explore the Pb-Sr-Nd-Hf isotopic evolution of much smaller OIVs in the Fieberling-Guadalupe Seamount Trail (FGST) and small, near-ridge generated seamounts in the same region. In particular, we investigate whether we can extend the Hawaiian models to Jasper Seamount in the FGST, which displays three distinct volcanic stages. Each stage has characteristic variations in Pb-Sr-Nd-Hf isotopic composition and trace element enrichment that are remarkably similar to the systematics observed in Hawaii: (1) The most voluminous, basal “shield building” stage, the Flank Transitional Series (FTS), displays slightly isotopically enriched compositions compared to the common component C and the least enriched trace elements (143Nd/144Nd: 0.512866–0.512909, 206Pb/204Pb: 18.904–19.054; La/Sm: 3.71–4.82). (2) The younger and substantially less voluminous Flank Alkalic Series (FAS) is comparatively depleted in Sr, Nd, and Hf isotope compositions plotting on the side of C, near the least extreme values for the Austral Islands and St. Helena. Trace elements are highly enriched (143Nd/144Nd: 0.512912–0.512948, 206Pb/204Pb: 19.959–20.185; La/Sm: 9.24). (3) The Summit Alkalic Series (SAS) displays the most depleted Sr, Nd, and Hf isotope ratios and is very close in isotopic composition to the nearby near-ridge seamounts but with highly enriched trace elements (143Nd/144Nd: 0.512999–0.513050, 206Pb/204Pb: 19.080–19.237; La/Sm: 5.73–8.61). These data fit well with proposed multicomponent melting models for Hawaii, where source lithology controls melt productivity. We examine the effect of melting a source with dry peridotite, wet peridotite, and pyroxenite, calculating melt productivity functions with depth to evaluate the effect of potential temperature and lithospheric thickness. This type of melting model appears to explain the isotopic variation in a range of small to large OIVs, in particular for OIVs occurring far from the complicating effects of plate boundaries and continental crust, constraining their geodynamic origin.

Received 10 September 2008; accepted 26 November 2008; published 3 February 2009.

Citation: Konter, J. G., H. Staudigel, J. Blichert-Toft, B. B. Hanan, M. Polvé, G. R. Davies, N. Shimizu, and P. Schiffman (2009), Geochemical stages at Jasper Seamount and the origin of intraplate volcanoes, Geochem. Geophys. Geosyst., 10, Q02001, doi:10.1029/2008GC002236.

Headwave Inc. Donates Software

2009-01-26T16:42:00.000-08:00

Headwave Inc. has donated to the department their Prestack AVO software. This software will aid students to meet the challanges of seismic data interpretation and oil and gas exploration/production careers. Headwave's software solution, gives easy access to potentially enormous multi-terabyte prestack datasets from single PCs.
Overview
Routine 3D visualization of prestack data can reduce turn-around time at all stages of a project’s lifecycle, from real-time visualization and analysis of shot gathers during acquisition, to true 3D QC of gathers during data processing (no more sparse sampling of gathers in 2D viewers!) -- to new insights into the quality of poststack datasets and horizons for interpreters and drilling decision makers.
Viewing Prestack Gathers
Prestack for Interpreters allows users to view any type of gather, (shot, receiver, cmp, etc.) as either a 3D volume in its own domain space, or, in the case of midpoint gathers, linked intuitively to either a corresponding poststack inline or crossline.
Data Management
Data management of terabytes of prestack data is a non-trivial part of data processing and exploration & production. To counter the challenges of frequent, cumbersome transfers of huge datasets Headwave has introduced a unique compressed, multi-dimensional, multi-resolution dataformat. By compressing the original datasets in multiple dimensions, it is possible to reduce the size of the file(s) to a level where logistics is no longer a bottleneck to the use of prestack data.

Explore the uniqueness of their technology and why it matters

Department Announces a New Undergraduate Advisor

2009-01-20T17:06:00.001-08:00

Starting Spring 2009 the Department of Geological Sciences has a new Undergraduate Advisor.

Dr. Jared R. Morrow

Jared will provide help and program planning for all undergraduate students in the Geological Sciences at SDSU. He will advise program requirements, course selection, educational interests or concerns, difficulty with courses or course load, and short- and long-term goals.
Jared replaces Dr. David L. Kimbrough who will now serve as chair of the Departments assessment program.

Contact Information:
Email: jmorrow@geology.sdsu.edu
Phone: 619.594.1395
Fax: 619.594.4372
Office: GMCS 228A
Lab: GMCS 117

Mail Address:
Dept. of Geological Sciences
5500 Campanile Drive, MC-1020
San Diego State University
San Diego, CA 92182-1020
USA

SEMINAR - Kathleen R. Johnson

2009-01-16T16:58:00.000-08:00

Reconstructing Asian Monsoon History from Chinese Speleothems

Kathleen R. Johnson
Department of Earth System Science
University of California, Irvine

Wednesday, February 18th, 2009

While we know that modern anthropogenic climate change is superimposed upon significant natural climate variability, the instrumental record of climate is too short to capture the full range of this variability. In order to fully understand and predict future changes, therefore, high-resolution, welldated paleoclimate records are needed to extend the record. This paleoclimate data allows us to quantify natural variability and learn how the climate system responded to past changes in boundary conditions and forcings and provides a vital test for state-of-the-art coupled climate models. Cave calcite deposits (speleothems) are widely studied paleoclimate archives that have led to significantly improved records of past climate variability over a wide range of timescales (seasonal to glacialinterglacial), most notably in low-latitude and monsoon regions. Speleothems are well-suited for terrestrial climate reconstruction because: they tend to be very pure and well-preserved; they usually contain clear visible growth banding which, like tree rings, is often annual in nature; they can be very precisely dated using uranium-series radiometric dating methods; and they contain numerous types of physical and geochemical proxy data. In this lecture, I will present an introduction to speleothem based paleoclimate proxies and describe ongoing modern calibration studies we are conducting at Heshang Cave, China to test and develop new seasonal resolution proxies of Asian monsoon rainfall. In addition, I will present multiple records of Asian monsoon rainfall obtained from stable isotope and trace element variations in Chinese speleothems and discuss the important role of the Asian monsoon in the global climate system.

SEMINAR - Jared Kluesner

2009-01-16T16:54:00.000-08:00

Geologic and Hydrologic Role of Sill Intrusion and Delineation of the Oceanic Crustal Boundary in the Central Gulf of California

Jared Kluesner
Marine Physical Laboratory
Scripps Institution of Oceanography

Wednesday, February 11th, 2009

Geologic and Hydrologic Role of Sill Intrusion and Delineation of the Oceanic Crustal Boundary in the Central Gulf of California High-resolution multichannel profiles recently shot in the central Gulf of California display concordant and discordant (concave-upwards) sills intruded shallowly within (I) young sediments in the axial troughs of Guaymas, Carmen and Farallon Basins, (II) off-axis in the basin floors, and (III) within the sediment cover of subsided and extended continental crust. We interpret some imaged sills as 3D saucer-shaped intrusions based on their concave-upward profiles, the overlying circular and elliptical plans of domal uplifts of the present multibeam-mapped seafloor, and their striking resemblance to field-mapped and 3-D seismically imaged saucer-like sills. Vertical zones of high-amplitude, disturbed reflectors leading up from sills are probably "blow-out pipes" acting as conduits for hydrothermal fluids and gases migrating up and away from the heated sill-sediment contact aureole, forming pockmarks on the present seafloor. Bright spots, dim spots, phase reversals, and acoustic turbidity in the sediments above sill intrusions suggest the presence of hydrocarbons and fluid flow throughout the study area. Seismic evidence of sill intrusions into the shallow crust throughout the central gulf suggests melt is being delivered not just to spreading centers, but to a much broader area of oceanic and continental crust. We have improved the delineation of the oceanic/continental crustal boundary in the central and southern gulf by sampling igneous basement (tholeiitic basalt and gabbro = oceanic; granitic = continental), by identifying the extent of magnetic stripes diagnostic of seafloor spreading, by interpreting multichannel reflection profiles, and by geomorphology. Although the "boundary" is somewhat smeared by the intrusion of shallow sills (some known to be tholeiitic, most inferred to be) into the cover of both granitic and oceanic basement, we find no evidence of "transitional zones" of hybrid crust; at those sheared and rifted margins where basement is accessible, granite commonly abuts tholeiitic flows and sills. Seafloor spreading magnetic anomalies, with low amplitudes and broad transition widths, can be read out to C2Ar in Alarcon Basin, and C2An.1 in Guaymas Basin (but only on profiles that avoid major off-axis seamounts and intrusions); in both cases they indicate significantly slower accretion during the first 1 m.y. of spreading, presumably because of concurrent continued extension of the rifted margin. Widespread sill intrusion over continental basement does hamper identifying the ocean/continental boundary on seismic reflection profiles, and because the already thin Cordilleran crust was clearly highly extended during prolonged rifting we do not think that crustal thickness is a reliable criterion for the extent of oceanic crust.

Short Course Announcement

2009-01-16T15:22:00.000-08:00

FEBRUARY 2 & 3, 2009; 6:00-9:30 pm (Two Evenings)
How to Recognize Continental Trace Fossils in Outcrop and Core:
Implications to Interpreting Environments of Depositional and Significant Surfaces

Leader:
Dr. Stephen T. Hasiotis
The University of Kansas–Lawrence
Associate Professor of Geology &
Coeditor of the journal PALAIOS

Dr. Hasiotis is a leading expert on continental trace fossils and on interpreting ancient organism–media interactions preserved in the geologic record. This popular short course has been presented to numerous academic and professional organizations.

Prerequisites
The short course is tailored to professional petroleum and academic geologists and students. People interested in this short course are those geologists who work with core and outcrop sections that are or may be of continental origin or that have been overprinted by processes associated with terrestrial and freshwater aquatic conditions; including both clastic and carbonate lithology. A previous course in geology is desired. There is no cost for the course, but participants are requested to obtain a copy of the course text: Continental Trace Fossils: SEPM Short Course Notes 51, 130 p. (ISBN 1-56576-092-1). The text can be purchased through SEPM (http://www.sepm.org) or onsite during the course for $40.

Objectives and Content
The type, distribution, and tiering of continental trace fossils are useful tools in outcrop and core for interpreting continental environments of deposition and their post depositional histories. This short course presents the latest ichnological concepts and provides a comprehensive photoglossary of nearly the entire suite of major terrestrial and freshwater trace fossils that geoscientists will encounter. The short course presentation and notes are divided into two sections: 1)concepts and fundamental principles that explain how terrestrial and freshwater-aquatic trace fossil behavior is interpreted and used to define environments of deposition and to recognize paleosols; and 2) a hands on study of outcrop and core examples of continental trace fossils using the photoglossary of continental tracefossils with explanations and idealized line drawings.

Part 1: we discuss fundamental concepts of continental ichnology by examining the life cycle of organisms in modern depositional systems. We discuss short comings in the new directions in ichnology, and we elaborate on the differences between continental and marine organisms and resultant differences in their traces. Photos and illustrations of modern and ancient trace making organisms and their traces will be used to illustrate how the controls on behavior and distribution of continental organisms can be applied to interpreting continental environments in the rock record. An ichnological framework for continental systems is presented that is based on analogy to specific environmental controls operating in modern terrestrial and freshwater environments. Alluvial, lacustrine, eolian, and transitional depositional settings form potential ichnofacies, which are defined in detail by their ichnologic composition. The framework uses examples of modern and ancient trace fossils to define specific environments that will be presented as hand samples and rock sectioned specimens.

Part 2: we use section two of the short course notes, which is a photoglossary of outcrop and core examples of continental trace fossils. At the end of this section is a reference sheet that contains representative color photographs and line drawings of each type of trace fossil in the photoglossary. This sheet also includes a list of abbreviations of continental trace fossils to be used when measuring sections in the field or describing core at an offsite location. We work with continental trace fossils in hand specimens, rock section, and few core samples to learn to how to recognize and identify these types of ichnofossils. We will also use examples of ichnofossils as major constituents of paleosols. Many of the continental trace fossils occur in paleosols where the color differences between the trace fossils and surrounding matrix accentuate the morphology of the trace fossil. The combination of text, line drawings, photographs, and figure explanations allows the user to identify the trace fossil as well as to determine the paleoenvironmental, paleohydrologic, and paleoclimatic settings.

FOR MORE INFORMATION OR TO REGISTER FOR THE COURSE, PLEASE CONTACT:
Dr. Jared Morrow, SDSU Department of Geological Sciences
jmorrow@geology.sdsu.edu, 619-594-1395
The course will be held at SDSU Dept. of Geological Sciences
(http://www.geology.sdsu.edu); room CSL 422

REGISTRATION DEADLINE IS FEBURARY 1, 2009

PDF Flyer

The 1,700-foot Tall Tsunami that Struck Alaska - Can It Happen Again?

2009-01-14T20:11:00.000-08:00

On the night of July 7th, 1958 the world’s largest Tsunami engorged Alaska's Lituya bay, located about 250 miles west of Juneau. It was 1,700 feet or 520 meters, almost twice the height of the Eiffel Tower.
The Tsunami was triggered by a magnitude 8.3 earthquake caused an enormous landslide along the Fairweather Fault. The resulting crash of rock into water, caused the largest wall of water in human history. The deadly wave hurtled at jet speeds and wiped out everything within a four mile radius.
Fortunately Lituya Bay was virtually uninhabited, otherwise it would have caused unprecedented destruction, far greater than the tsunami that struck Thailand in 2004.
At the time of the colossal wave, there were only three fishing boats anchored in the bay and amazingly only one sank, with two people losing their lives. The other boats were able to surf the crest of the tsunami.
The Science Channel and Dr George PC quoted one of the survivors Howard G. Ulrich in a recent article about the tsnumami. Ulrich heard the sound of the enormous wave ripping through the land and obscuring the sky, he reportedly said to his 8-year-old child “Son…it’s time to pray.”
Can a similar tsunami strike the westcoast of the U.S. again? Geological evidence makes it almost a certainty -the region is the heart of the world's most active sesmic zone: the Pacific Rim of Fire.
On January the 26th, 1700, sometime around 9 in the evening local time, the Juan de Fuca segment of the planet beneath the ocean in the Pacific Northwest moved. Suddenly. It slipped some 60 feet eastward beneath the North American plate, and caused a monster quake of approximate magnitude 9. It set in motion tsunamis that struck the coast of North America and traveled to the shores of Japan.
Researchers believe that these megaquakes occur every 400 to 500 years or so.
Kim Olsen of SDSU and his team created a supercomputer-powered “virtual earthquake” program that allowed them to recreate such an earthquake. This program encompassed the work of scientists from SDSU, San Diego Supercomputer Center at UC San Diego and the U.S. Geological Survey.
In addition, to ensure that the entire representation of what could happen is accurate, William Stephenson of the USGS worked with Olsen and Andreas Geisselmeyer from Ulm University in Germany to create an accurate representation of the earth’s subsurface layering in that area. This “velocity model” – the first of its kind – expresses how the structure will bend, reflect, and change in size and direction.
Naturally, what they learnt didn’t necessarily send anyone home to bed with warm fuzzy feelings of safety (although Andreas is probably feeling pretty cozy over in Germany).
Their scenario depicted a rupture beginning in the north and propagating toward the south along the 600-mile long Cascadia Subduction Zone (an area where two tectonic plates move towards one another, forcing one to slide beneath the other). In their scenario, the ground moved about 1.5 feet per second in Seattle, nearly 6 inches per second in Tacoma, Olympia and Vancouver, and 3 inches in Portland, Oregon.
“We also found that these high ground velocities were accompanied by significant low-frequency shaking, like what you feel in a roller coaster, that lasted as long as five minutes – and that’s a long time,” said Olsen.
“One thing these studies will hopefully do is to raise awareness of the possibility of megathrust earthquakes happening at any given time in the Pacific Northwest,” Olsen added. “Because these events will tend to occur several hundred kilometers from major cities, the study also implies that the region could benefit from an early warning system that can allow time for protective actions before the brunt of the shaking starts.”
Region specific, this is bad news for the North West for two reasons; one, because the combined long-duration shaking and high ground velocities raise the possibility that such an earthquake could inflict major damage on downtown Seattle; and two, areas like Seattle, Tacoma and Olympia sit on top of sediment filled geological basins, thus, amplifying the waves generated by major earthquakes.
Reason one why scientists bother running these simulations. Reason number two: “The information from these simulations can also play a role in research into the hazards posed by large tsunamis, which can originate from such megathrust earthquakes like the ones generated in the 2004 Sumatra-Andeman earthquake in Indonesia,” said Olsen.Posted by Casey Kazan with Josh Hill.

Source:
http://www.environmentalgraffiti.com/offbeat-news/the-1700-feet-tsunami-that-struck-alaska/927

Vic Camp - Recipient of a 2009 University Grants Program awards

2009-01-08T11:32:00.000-08:00

San Diego State University Graduate & Research Affairs recently announced recipients of the 2009 University Grants Program (UGP) awards.

The Department of Geological Sciences Victor Camp, was awarded a UGP for "Geochronology and Geochemistry of the Columbia River Flood Basalts, Buffalo Hills, Nevada"

The UGP was created to integrate three internal funding mechanisms through which faculty may derive support for creative and scholarly research, including:

Research, Scholarship and Creative Activity
Faculty Development Program
Faculty Grant-in-Aid

Funding was also provided by the Adams Humanities Endowment. Of the 120 applications received, 53 awards were granted totaling more than $410,000.

SEMINAR - Stephen T. Hasiotis

2009-01-05T14:44:00.000-08:00

Ichnology for the 21st Century: Understanding the differences between continental and marine trace fossils, with implications to the diversity, distribution, and evolution of soil biota

Stephen T. Hasiotis
Department of Geology
University of Kansas
Coeditor PALAIOS

Wednesday, February 4th, 2009

The study of ichnology has come a long way since its inception and it continues to evolve. In particular, progress is being made in understanding the implications of trace fossils in the continental realm and how they can be used in conjunction with subdisciplines in geology to reconstruct the past. Organisms in all domains of life display behaviors that greatly expanded our definition of ichnology. Ichnology is the study of all organism behavior-not just animals. Accordingly, a trace fossil is the product of an organism interacting with a medium in an environment, which generates a three-dimensional physical structure-the resultant trace fossil can be micrometers to kilometers in scale. Though behaviors and resultant trace fossils may be similar morphologically in continental and marine settings, the organisms and behaviors that produced them and the physicochemical factors that controlled their distribution, depth, diversity, and abundance can be strikingly different. Ongoing research with modern terrestrial and aquatic organisms in the field and laboratory reveal the behaviors behind the production of burrow morphologies whose genesis and significance would otherwise be misinterpreted. The study of these modern traces, organisms, and their distribution allows us to recognize how their burrow morphologies and sedimentary associations record the environmental, ecologic, hydrologic, and climatic settings in which they are formed. Comparison of these modern structures and their tracemakers to trace fossils in continental deposits in the geologic record provide stronger clues about the implications of trace fossils for interpreting and reconstructing the sequence of events and conditions that produced those deposits. They also provide information on the evolution and radiation of organisms and ecosystems where the body fossil record is poor. As a result of these new research endeavors, trace fossils are being used to (1) extend the fossil record and understand the radiation of organisms, (2) interpret more accurately environments of deposition and the extent of pedogenesis that have modified those deposits, (3) contribute to understanding better the effects of climate change on biota, environments, and hydrologic systems, and (4) correlate significant surfaces in continental strata and identify subtle but significant shifts in physicochemical conditions and environments.

Spring 2009 Department Seminar Schedule

2009-01-05T13:56:00.000-08:00

Stephen Hasiotis - University of Kansas, Department of Geology

February 4th

Ichnology for the 21st Century: Understanding the differences between continental and marine trace fossils, with implications to the diversity, distribution, and evolution of soil biota

Jared Kluesner - Scripps Institution of Oceanography, Marine Physical Laboratory

February 11th

Geologic and Hydrologic Role of Sill Intrusion and Delineation of the Oceanic Crustal Boundary in the Central Gulf of California

Kathleen R. Johnson - Department of Earth System Science, University of California, Irvine
February 18th

Reconstructing Asian Monsoon History from Chinese Speleothems

David Bowman - California State University Fullerton, Department of Geological Sciences

March 18th

Greg Hirth - Woods Hole Oceanographic Institution

March 25th

Elizabeth Cochran - University of California Riverside, Department of Earth Sciences

April 8th

Bruce Lieberman - University of Kansas, Department of Geology

April 15th

Brandon Browne - California State University Fullerton, Department of Geological Sciences

April 22nd

Shawn Wright - Arizona State University, Department of Geological Sciences
May 6th

*All seminars start at 1pm at San Diego State University in room CSL 422 unless otherwise noted

Jared Warner - 2009 SDAG Scholarship Winner

2008-12-16T22:26:00.000-08:00

We are pleased to announce that SDAG has awarded the 2009 SDAG Scholarship to Jared Warner for his research project entitled "Biotic Response of Ostracodes to the Middle Eocene Climatic Optimum (MECO) in the Southern Indian Ocean".

Jared will receive a scholarship check and will present his research at an SDAG meeting this spring (usually the third week in March).

SAN DIEGO ASSOCIATION OF GEOLOGISTS

Frank Forcino and Jared Warner - Sigma Xi Grant-in-Aid of Research

2008-12-12T00:39:00.000-08:00

We are pleased to announce that the Sigma Xi Committee on Grants-in-Aid of Research has awarded grants to support the research of Frank Forcino and Jared Warner.

The Sigma Xi Grants-in-Aid of Research (GIAR) program has been providing undergraduate and graduate students with valuable educational experiences for more than 80 years. By encouraging close working relationships between students and faculty, the program promotes scientific excellence and achievement through hands-on learning. The Sigma Xi Grant-in-Aid of Research program has a highly competitive application process and only approximately 20% of applicants receive any level of funding.

Grants-in-Aid of Research Program

Thesis Defense - Fall 2008 - Tiffany Schillereff

2008-12-11T20:00:00.000-08:00

Potential Controls Affecting Gastropod Biomass in the the High Intertidal Zones at Neighboring Locations

Tiffany Schillereff
B.S. Candidate
Advisors Dr. Stephen Schellenberg

Friday, December 12th, 2008 CSL 422, 9:40am

ABSTRACT
San Diego California’s coastlines include rocky intertidal zones that contain an abundance of the Class Gastropoda. What are the potential controls on gastropod abundance and size? Do wave energy, anthropogenic impact, substrate lithology and predation play a role?
The locations in this study were Bathtub Rock and Dike Rock. Bathtub rock is located approximately 1 km south of the main parking lot at Torrey Pines State Beach. Dike Rock is located 1.1 km north of Scripps Institute of Oceanography pier and there is an approximate 3.3 km distance in between the two locations.
Bathtub rock is a medium grained sandstone sea stack that waves eroded from the Delmar Formation. Dike Rock is a basaltic andesite volcanic intrusion. Dike Rock is part of the Scripps Marine Coastal Reserve (no harvesting of specimens or shell collection allowed) and a submarine canyon (Scripps Canyon) is located off shore. Bathtub rock is not protected and no submarine canyon is located off shore.
Abundance counts, size measurements, and photographs (for identification) were collected in the upper middle to lower upper intertidal zones at laterally correlated MLLW’s at the two locations. These counts and measurements were also collected on the south side and north side at each location. These data were collected over a four month interval from September to December 2008.
The observed gastropods in the study include: Littorina planaxis, Collisella digitalis, Collisella scabra, Lottia gigantea and Nucella emarginata. N. emarginata was only observed at Dike Rock. All species of gastropods in this study prefer the upper middle to lower upper intertidal habitat. All but N. emarginata are algae grazers. N. emarginata is predatory and feeds on mussels, barnacles and other gastropods.
Overall gastropod abundances were higher at Bathtub rock with an average abundance of 537 ± 268 (1 σ) gastropods/m2 vs. an average abundance of 247 ± 56 (1 σ) gastropods/ m2 at Dike Rock. South side abundances were higher at both locations than the north side abundances. The south side of Bathtub Rock had an average of 727 ± 118 (1 σ) gastropods/m2 whereas the south side of Dike Rock had an average of 288 ± 47 (1 σ) gastropods/m2. The north side of Bathtub Rock had an average of 348 ± 58 (1 σ) gastropods/m2 whereas the north side of Dike Rock had an average of 207 ± 26 (1 σ) gastropods/m2. Overall gastropod size varied between the two locations with Dike Rock having an overall larger average size of 15 mm versus 7 mm at Bathtub Rock.
The higher abundance of gastropods at Bathtub rock could be due to the site’s more easily bioeroded sandstone (facilitating more dwelling structures) and fewer predatory N. emarginata gastropods and sea stars. The higher abundances on the southern side of both sites could reflect the average west-northwest incoming wave energy, which might preferentially dislodge gastropods from the northern sides. Larger average specimen size at Dike Rock could be due to the presence of the submarine canyon which refracts wave energy away from the site, providing full growth potential. Gastropods at wave-swept sites due to the probability of dislodgement by mechanical drag forces increases morality rates before they can achieve maximum size (Denny et al. 1985.) Another factor that could be affecting the larger size at Dike Rock is that it is a protected marine reserve. Anthropogenic impacts such as harvesting specimens have contributed to size declination over time (K. Roy et al. 2007.) Larger gastropod species Lottia gigantea and Nucella emarginata are present at this site which could be another factor.

Thesis Defense - Fall 2008 - Rumi Takedatsu

2008-12-05T21:03:00.000-08:00

Study of crustal structure in the Caucasus and Caspian regions using receiver functions

Rumi Takedatsu
B.S. Candidate
Advisors Dr. Rob Mellors

Friday, December 12th, 2008 CSL 422, 9:00am

ABSTRACT
The Eurasia-Arabia collision has created complex tectonics and structure in the Caucasus and Caspian region. In particular, Caspian Basin has a very different lithospheric structure from the surrounding region and the origin of the basin and nearby structures, such as the Kura Depression, are not well understood. This study will map the main crustal structure and estimate Moho depth under each seismic station using receiver functions. Receiver functions are a well-established technique to determine the boundary between crust and upper mantle (Moho) using three-component broadband seismograms. Using seismic data from 14 broadband stations in Azerbaijan, we generate receiver functions for 90 events. The Moho depth beneath each is determined by forward modeling the receiver functions using a reflectivity method and a two-layer crust. The receiver functions show clear indications of dipping structure as well as thick sediments under many stations which make modeling difficult. The preferred results show Moho depths of 37 - 43 km under the Greater Caucasus, 46 km under the Lesser Caucasus, 34 – 42 km in the Kura Depression, and 31 – 35 km along the western boundary of the South Caspian Basin. Crustal thickness thins towards the Caspian

SEMINAR - Robert Gaines

2008-12-03T21:06:00.000-08:00

Paleoenvironments, Paleoecology, and Exceptional Preservation in Burgess Shale-type Deposits

Robert Gaines
Department of Geology
Pomona College

Wednesday, December 10th, 2008

Cambrian Burgess Shale-type (BST) deposits occur worldwide and offer a remarkable window on the initial Phanerozoic radiation of the Metazoa. However, BST deposits also represent significant deviations from the constraints that govern the typical operation of the fossil record. These deviations remain to be adequately accounted for, hindering interpretations of the paleoecology of their exceptional biotas and the environments in which they lived. This talk will provide an overview of ongoing research towards developing a model for understanding paleoenvironments, paleoecology, and exceptional preservation in BST deposits, using data from 12 deposits of North America, Scandinavia and South China. Recently, elemental mapping of a survey of BST fossils demonstrated that the mode of fossilization is unique and common to all deposits. Thus, preservation of BST assemblages represents a single phenomenon that may share a common cause in all deposits in which it occurs. Sedimentologic and stratigraphic data indicate that BST deposits occur in a particular physical depositional window that acted as a first-order control, determining where exceptional fossilization occurred. Ichnologic and geochemical data indicate that, within the favorable physical depositional setting, benthic redox conditions exerted the next control. BST deposits occur at the transition from oxic to anoxic benthic environments and demonstrate dynamic redox conditions during deposition; exceptional fossils are confined to anoxic intervals. The chemistry of the early burial environment is interpreted to have exerted the final control. Ongoing work using the δ34S system from a core through the Chengjiang deposit extracted in July 2008 will provide a test of the hypothesis that sediment sealing by early carbonate cements promoted an early cessation of decay. Constraints at each tier, from the regional scale to the micron scale, were strongly favored by the prevalence of large epicratonic seaways in the Cambrian and by greenhouse conditions.

Thesis Defense - Fall 2008 - Matt Burgess

2008-12-03T11:28:00.000-08:00

Characterizing an Artificial-Recharge Site in a Desert Environment Using Time-Domain Electromagnetics

Matt Burgess
M.S. Candidate
Advisors Dr. George Jiracek, Dr. Paul Bedrosian (USGS)

Friday, December 12th, 2008 CSL 422, 11:00am

ABSTRACT
Time-domain electromagnetics (TEM) were applied to characterize the
subsurface in the vicinity of a proposed artificial hydraulic recharge
site. Because of the investment involved, it is important to know the
possible barrier effect of a major fault situated near the proposed
recharge site. In this study, a series of TEM soundings were made to
estimate the depth to water on both the north and south sides of the
Pinto Mountain Fault. Results show strongly contrasting resistivity
structures across the fault. These findings are consistent with
expected water levels south of the Pinto Mountain Fault and suggest
that the fault does, in fact, act as a barrier to flow in the vicinity
of the proposed artificial recharge site.

Thesis Defense - Fall 2008 - Jason Ricketts

2008-12-03T11:07:00.000-08:00

Crustal Structure of the Caucasus/Caspian region using gravity and receiver functions

Jason Ricketts
B.S. Candidate
Advisor Dr. Rob Mellors

Friday, December 12th, 2008 CSL 422, 9:20am

ABSTRACT
The area west of the South Caspian basin is an area of complex and uncertain tectonic structure. Thick sediments within the Kura Depression mask the basement and its subsurface geology is poorly constrained. Forward modeling of receiver functions provides initial constrains. However, a good match is sometimes difficult due to the thick sediments. To further constrain the sedimentary thickness, a 2-D gravity profile from EGM2008 is forward modeled using 2 layers over a half-space.
The 2-D profile extends between the two seismic stations BRD and ALI, and the initial model was based on receiver function results. Gravity data was then used to verify these results as well as to provide any additional constrains on the model.
A proposed cross-section shows a depth to basement of 8 km beneath BRD, and a depth of 18 km beneath ALI. Gravity data also suggests that the sediment-basement contact between these two stations is highly irregular. A model where the basement displays an anticinal shape fits the gravity data as well as the receiver functions. Also located to the south of the profile is the Saatly deep well, which reaches a depth of more than 8 km without hitting basement. The westward component of motion of the South Caspian basin relative to the Kura Depression creates E-W shortening in this region, which can be supported by this model.

Thesis Defense - Fall 2008 - Afton Van Zandt

2008-12-03T10:53:00.000-08:00

Southern Coyote Creek Fault to Superstition Hills Fault: New Insight to the San Jacinto Fault System

Afton Van Zandt
M.S. Candidate
Advisors Dr. Rob Mellors , Dr. Thomas K. Rockwell, and Dr. Douglas A. Stow

Friday, December 12th, 2008 CSL 422, 10:00am

ABSTRACT
The Superstition Hills fault (SHF) is an active fault in the San Jacinto fault zone that also creeps aseismically. 58 interferograms from ERS-1 and ERS-2 satellite data (descending, track 356, frame 2943) spanning a time period from 1992 to 2000 were analyzed to measure surface deformation along and near the fault. Interferograms were analyzed separately and as a stacked image. Clear signals due to both groundwater extraction and tectonic movement were observed. Fault creep is observed along the Superstition Hills and Elmore Ranch faults. A broad zone of line-of-sight deformation extends from the north end of the Superstition Hills fault to the southernmost Coyote Creek fault. Phase gradient images were useful in identifying faults, and revealed a previously unknown extension of the Coyote Creek fault.
The existence of the fault was confirmed by field measurements, which included both surface mapping and a trench across the fault. The fault exhibited indications of recent motion including both vertical and strike-slip components.
The InSAR data is modeled using a series of finite faults in an elastic half-space. The observed deformation along the Superstition Hills fault and Elmore Ranch fault can be modeled assuming shallow (< 5 km) creep. Various models were tested to explain the pattern of surface deformation between the Superstition Hills and Coyote Creek fault. The preferred model included a northwest trending vertical right-lateral strike-slip fault north of the Elmore Ranch fault.

SEMINAR - Kim Bak Olsen

2008-12-01T16:07:00.000-08:00

LA's Future Earthquake

Kim Bak Olsen
Department of Geological Sciences
San Diego State University

Wednesday, December 3rd, 2008

SacramentoGrilo rated fourth most "hot" professors by RateMyProfessors.com.

2008-12-01T14:59:00.001-08:00

'Hot' Professors
RateMyProfessors.com ranks two SDSU professors as most attractive.

SDSU'S Corey Manchester, lecturer in the Department of Mathematics and Statistics, and Isabelle SacramentoGrilo, lecturer for the Department of Geological Sciences, were ranked third and fourth respectively for hottest professors by RateMyProfessors.com, an online rating site for college, university and junior college professors.

The website recently ranked the top 10 rated universities, professors at universities, professors at junior colleges and hottest professors, using information gathered over the past two and a half years, with an emphasis on most recent ratings.

Each year RateMyProfessors.com's annual rankings capture the highest rated college professors and faculties on the site.

About the rankings

RateMyProfessors.com uses a five-point Likert scale, as well as a binary scoring system, for student-generated professor ratings.

For each of the professor lists, each individual rating value was first standardized around its mean and a weighted score was created using standardized scores from the years 2006, 2007 and 2008 to date.

Using the weighted score, professors were ranked from high to low. Only professors with 10 ratings or more were included to provide statistical significance. All professors were verified as actively teaching in the current semester by each school at the time the lists were compiled.

About the website

RateMyProfessor.com is a website where students can rank their professors on easiness, helpfulness, clarity, rater interest and "hotness."

In the past year, monthly traffic to the site has increased approximately 18 percent in page views, and about 20 percent in visits on average, according to Omniture. The lists were culled from RateMyProfessors.com's extensive database of more than 7.5 million student-generated ratings of over 1,000,000 college professors.

The Independent Planetologist / Favored Lecture Topics

2008-11-29T09:59:00.000-08:00

Looking for a Science Lecture for your local group....
ask the Independent Planetologist - Dr. Gary Peterson

The Independent Planetologist / Favored Lecture Topics:

"FAVORED TOPICS

Some lectures are one of a kind. Others are given over and over again, sometimes under different titles (in this list, only the latest title is indicated). The content of a talk can vary quite considerably, depending on the audience. Some talks tend to 'evolve' as they are repeatedly given. Listed below are some favored topics. The 'Planet Earth Series' of talks deal with earthly topics only. Click on the title and a list of venues will appear. (* indicates that the talk has been given 5 or more times, ** 10 or more times and *** 20 or more times.)

'PLANET EARTH SERIES'
'DOOMSDAY ASTEROIDS AND COMETS' **
'GEOLOGY: THE EARTH AS A PLANET'
'COLLISIONS OF COMETS AND PLANETS' **
'A FIELD TRIP THROUGH THE SOLAR SYSTEM'
'METEORITES AND OTHER SPACE DEBRIS'**
'SALT WEATHERING ON EARTH AND MARS'
'IMPACT STRUCTURES ON THE TERRESTRIAL PLANETS'
'BASALTIC FLOODING OF PLANETARY LANDSCAPES' **
'EVOLUTION OF THE GALILEAN SATELLITES OF JUPITER'
'THE SULFUR VOLCANISM OF IO'*
'EXPLORING THE MARTIAN DESERT' **
'THE GEOLOGICAL CASE FOR LIFE ON MARS' ***
'LOSS OF VOLATILE CONSTITUENTS FROM THE TERRESTRIAL PLANETS' **
'MARS: WHERE DID ALL THE WATER GO?' **
'EXPLORING THE LUNAR LANDSCAPE'*
'WHY IS MARS RED?' ***
'EUROPA: THE OTHER OCEAN'*
'IS THERE LIFE ELSEWHERE IN THE SOLAR SYSTEM?'*
'VENUS: EXPLORING THE INFERNO' **
'ATMOSPHERES AND OCEANS OF THE TERRESTRIAL PLANETS' **
'MERCURY: THE FORGOTTEN PLANET'**
'THE GREAT MARTIAN CLIMATE CHANGE'*
'THE PROBLEM WITH PLUTO'*
'THE CAPTURE OF THE MOON'*
'THE CRYOGEN"

The Great Southern California ShakeOut

2008-11-11T07:36:00.000-08:00

At 10 a.m. on November 13, join millions of people throughout Southern California in the ShakeOut Drill, the largest earthquake preparedness activity in U.S. history!

Individuals, businesses, schools, colleges and universities will be spreading the word about earthquake preparedness throughout Southern California.

A week of special events featuring the largest earthquake drill in U.S. history, "The Great Southern California ShakeOut," has been organized to inspire Southern Californians to get prepared.

On Nov. 13, SDSU will activate its Campus Emergency Operations Center to participate in an exercise that will simulate the steps necessary to manage an incident such as an earthquake.

All members of the SDSU campus community are encouraged to periodically review earthquake preparedness information, including "Drop, Cover and Hold On" protocol, and help spread the word. Being prepared may prevent a disaster from becoming a catastrophe. Additional SDSU emergency preparedness information for students, faculty and staff may be found online.

Earthquake Simulations at SDSU
Kim Bak Olsen, Professor Department of Geological Sciences at San Diego State University, California discusses earthquake simulations.
Originally posted by SDSC on SDSC's CI Channel at: www.cichannel.org

SEMINAR - Aron J. Meltzner

2008-11-05T19:46:00.000-08:00

Earthquake Recurrence and Long-Term Segmentation near the Boundary of the 2004 and 2005 Sunda Megathrust Ruptures

Aron J. Meltzner
Tectonics Observatory
California Institute of Technology

Wednesday, November 19th, 2008

Simeulue Island, off the west coast of northern Sumatra, straddles the boundary of the 2004 and 2005 Sunda megathrust ruptures. The 2004 and 2005 earthquakes nucleated northwest and southeast of Simeulue, respectively, and each ruptured bilaterally toward the 100-km-long island. Cumulative uplift was 1.5 m at both the northwest and southeast tips of the island but diminished toward the island’s center, where uplift was 0.5 m or less. Hence, although the 2004 and 2005 uplifts overlapped, there was an uplift deficit, or saddle, on central Simeulue.
Postseismic and long-term interseismic behavior, as revealed by coral microatolls, suggests that the Simeulue Saddle is more than a transient feature. The Saddle was partially, but far from completely, filled in by postseismic slip through 2007. As much as ~20 cm of uplift occurred in the Saddle region during both the Nov 2002 and Feb 2008 M ~ 7.3 earthquakes, although even those contributions fail to erase the deficit. Microatoll morphologies indicate that, averaged over decades and longer, interseismic strain accumulation rates are lower in central Simeulue than at the island’s ends.
U-Th dates of fossil coral microatolls suggest that northern Simeulue, which was uplifted in 2004, experienced an earthquake couplet or triplet in the 14th-15th centuries. Sites there experienced modest uplifts in ~AD 1393 and substantially larger uplifts in ~AD 1454. Some evidence exists for a third event, earlier in the 14th century, that uplifted northern Simeulue, but there is no evidence for prehistorical events after ~1454. The apparent lack of coral living on any of the reefs of northern Simeulue between ~AD 1454 and the early 20th century suggests that the reefs were above sea level during that entire period.
South of the Saddle, prior uplifts occurred in AD 1907, 1861, 1843, and around 1799. The 1861 earthquake appears to have been the closest analog to 2005 in size and extent, with 1843 and ~1799 being smaller, and with 1907 apparently occurring updip.
The spatiotemporal distribution of coral diedowns around Simeulue indicates that earthquakes have repeatedly propagated into the Saddle from both the north and the south, but there is no evidence of any rupture that has ever propagated through the Saddle. Altogether, observations of the behavior of central Simeulue during the recent and older earthquakes, and during postseismic and interseismic periods, suggest that the Simeulue Saddle is a poorly coupled segment of the megathrust that serves as a persistent barrier to rupture.

SEMINAR - John A. Izbicki

2008-10-29T21:07:00.000-07:00

Sources of Fecal Indicator Bacteria in Urban Streams and Ocean Beaches, Santa Barbara, California

John A. Izbicki
United State Geological Survey
Hydrogeologist

Wednesday, November 5th, 2008

Fecal indicator bacteria (FIB) concentrations in urban streams and ocean beaches in Santa Barbara, Calif. can exceed water-quality standards for recreational water. During low flow, high FIB concentrations in urban streams were associated with point discharges from storm drains, and concentrations in urban streamflow varied three-fold over the course of a day as a result of small variations in storm drain discharge. Human-specific Bacteroides was present in some sampled storm drains. FIB concentrations were highest in stormflow runoff, although concentrations decreased as successive storms washed FIB from the urban watershed. Sources of FIB to near-shore ocean water included surface discharges from urban streams, and fecal material from birds associated with kelp and sand along the beachfront. FIB concentrations were higher during the ebb of the “spring” tide and decreased to less than the detection limit during low tide when 222Rn and electromagnetic seepmeter data show ground-water discharge to the ocean was greatest. Ground-water discharge and leakage from sewer lines were not sources of FIB to nearshore ocean water. Interpretations of the sources of FIB from Principal Component Analysis (PCA) of genetic (T-RFLP), molecular (PLFA), and trace-organic (such as caffeine, fecal sterols, and detergent metabolites) data generally agreed with interpretations supported by physical measures of water flow. The most robust PCA results were from PLFA data which explained 97 percent of the total variance within the first and second principal components. Less variance was explained in PCA analysis of T-RFLP and trace-organic data, although these tracers captured relations not apparent in PLFA data. Certain compounds lent themselves to specific interpretations on the origin of FIB. The T-RFLP data indicated an unexpectedly large diversity of microorganisms, including FIB, in shallow ground water where street runoff was discharged to beach sands.

Seismic Micro-Technology awards gift of Kingdom Software

2008-10-24T08:35:00.000-07:00

Seismic Micro-Technology awards gift of Kingdom Software valued at $1,192,896.58

The Department of Geological Science has just been awarded three-year grant of the Kingdom Suite seismic interpretation software (10 seat license valued at $1,192,896.58) through the University Gift program. This software is used widely in the petroleum industry and will be a great advantage for our students entering the petroleum industry as well as a valuable tool for research and interpretation of seismic reflection data.

The KINGDOM Software (TKS) enables intuitive, integrated geoscientific workflow spanning:

Interpretation: Pick horizons and faults, overlay seismic with well data, correlate formation tops, contour surfaces, and view in 2D or 3D.
Modeling: View 1D synthetic seismograms, create velocity models for time to depth conversions, and convert resistivity and density logs to velocity.
Analytics: Analyze pre-stack gathers, perform quick look log analysis, generate velocity volumes, conduct attribute analysis and create custom calculators.
Data Management: Manage multiple projects and migrate data between major interpretation software platforms.

University Program

The goal of SMT's Educational Grant Program is to put workstation software in the classroom so those students graduating from universities are equipped for the job market with workstation experience. The KINGDOM Software is utilized for both teaching and research at academic institutions in 27 countries worldwide.

As of January 1, 2008, SMT has donated thousands of software licenses to 143 colleges and universities around the world. We offer each institute multiple copies of KINGDOM software for their teaching lab and for the professor or instructor's use in classes. Beginning in 2001, three-year grants, including all maintenance support and updates, have been donated with a total estimated value of over one hundred million dollars ($100M).

http://www.seismicmicro.com/

New Member of the Family

2008-10-23T16:10:00.000-07:00

Nikolai Waldemar Peterson

Gary and Daria Peterson proudly announce the birth of their firstr child, Nikolai Waldermar Peterson.

Born: Thursday, October 6, 2008 at 4:22am,
9 lbs and 8 oz, 22 inches (15in head circumference).

SEMINAR - Frank Corsetti

2008-10-22T20:33:00.000-07:00

Stromatolites: Myths and Legends

Frank Corsetti
Department of Earth Science
University of Southern California

Wednesday, October 29th, 2008

Stromatolites are classically interpreted as “organo-sedimentary structures”, where layers and doming/branching result from microbial mats. As such, they could be considered quintessential ‘astrobiologic’ structures—a stromatolite, as a macroscopic manifestation of microbial processes, would be much easier to image remotely (on Mars, for example) than a microbe. While there is no doubt that some (perhaps most) stromatolites on Earth were formed with biologic influence, recent work has demonstrated that stromatolite-like structures have formed without biologic input. Can we tell the difference? When faced with determining the presence of life elsewhere in our solar system, “extraordinary claims require extraordinary evidence”—do stromatolites pass this test?

SEMINAR - Gregory J. Holk

2008-10-15T21:24:00.000-07:00

The Long-Term Hydrologic Cycle: Stable Isotope Clues for Fluid Pathways in Earth's Crust

Gregory J. Holk
Department of Geological Sciences
California State University, Long Beach

Wednesday, October 22nd, 2008

The circulation of aqueous fluids through the Earth’s crust has profound effects on its geologic evolution, the formation of ore deposits, the migration of hydrocarbons from source to sites of accumulation, and the storage of groundwater resources. Major crustal-scale fault zones and crustal heat distribution both play a major role to determine fluid pathways. Case studies that showcase the interplay between crustal thermal evolution and the permeable zones, such as major crustal shear zones, are presented to demonstrate the importance of fluids on the tectonic evolution of the Earth’s crust and the formation of ore deposits. These studies include: (1) the role of water in the magmatic and tectonic evolution of metamorphic core complexes at the Southern Omineca Belt, British Columbia (Holk and Taylor, 2007) and the southern White Pine Range, east-central Nevada, (2) metamorphic fluids and the evolution of the Cretaceous-Paleocene subduction zone complex in southern California with a focus on large-scale infiltration of metamorphic fluids generated during shallow subduction into the Eastern Peninsular Ranges Mylonite Zone (Holk et al., 2006) and the generation of these fluids from the Catalina and other subduction-related schists, (3) a 1 billion year fluid evolution of sedimentary basins that host the world's largest uranium deposits (Holk et al., 2003), and (4) Archean submarine hydrothermal systems associated with felsic caldera systems that host massive sulfide deposits (Holk et al., 2008).

References
Holk, G.J., Kyser, T.K., Chipley, D., Hiatt, E.E., and Marlatt, J. (2003) Mobile trace elements and Pb-isotopes during late-stage evolution of Protrozoic sedimentary basins hosting uranium deposits. Journal of Exploration Geochemistry, v. 80, p. 297-320.
Holk, G.J., Taylor, H.P., and Gromet, L.P. (2006) Stable isotope evidence for large-scale infiltration of metamorphic fluids generated during shallow subduction into the Eastern Peninsular Ranges Mylonite Zone (EPRMZ), Southern California. International Geology Review, v. 48, p. 209-222.
Holk, G.J., Taylor, B.E., Galley, A.G. (2008) Oxygen isotope mapping of the Archean Sturgeon Lake caldera complex, Northwestern Ontario, Canada. Mineralium Deposita, v. 43, p. 623-640.
Holk, G.J., and Taylor, H.P. Jr. (2007) 18O/16O studies of regional metamorphism, anatexis, extensional magmatism, meteoric-hydrothermal activity, and ore deposition in the Valhalla metamorphic core complex, British Columbia. Economic Geology, v. 102, p. 1063-1078.

Thesis Defense - Fall 2008 - Steven Stuart

2008-10-10T17:39:00.000-07:00

Groundwater and Surface Water Interactions at the Tijuana Estuary, San Diego County, California

Steven Stuart
M.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Kathy Thorbjarnarson

Monday, October 15th, 2008

ABSTRACT
The Tijuana Estuary is a unique coastal plain and wetland-dominated estuary influenced by tidal fluctuations and saltwater inflow from the Pacific Ocean and by intermittent freshwater inflow from the Tijuana River. The lower Tijuana River valley, the alluvial river valley that leads into the estuary, collects 96% of runoff in the 4,500 km2 Tijuana River watershed. Stream flow in the Tijuana River is ephemeral and regulated by precipitation events and dam releases upstream in the watershed. The quality of surface water is impacted by sewage discharges in Mexico and storm water runoff. Groundwater in the river valley flows west to the estuary and is impacted by local agricultural and sod farming activities. The purpose of this study was to evaluate the influence of groundwater and surface water from the lower Tijuana River valley on salinity levels in the estuary and to characterize the interaction between surface water and groundwater in the estuary in response to diurnal tidal fluctuations.
This study incorporated simultaneous monitoring of groundwater and surface water elevations and salinity in the lower Tijuana River valley and Tijuana Estuary over a period of 1.5 years. Seasonal variations in water levels and salinity were observed in the river valley and estuary; however, the estuary was influenced more by diurnal tidal fluctuations, high spring tides, major precipitation events, and surface water runoff. Groundwater and surface water salinity in the estuary was brackish to hypersaline. Hypersaline groundwater was measured in areas with low hydraulic conductivities that dictated slow infiltration rates and in areas that were inundated with ocean water during high spring tides. Hypersaline surface water was measured in estuarine channels that were temporarily disconnected to tidal flushing. Precipitation events dramatically affected salinity in surface water where salinity temporarily fell below brackish levels. In groundwater, precipitation events typically caused a short-term spike in salinity as the initial wetting front of infiltrating rainwater carried a higher concentration of dissolved salts from the shallow soil to the water table. Continued recharge by infiltrating rainwater gradually decreased salinity over a few days after the precipitation event.
These observations demonstrated that the Tijuana Estuary is a highly variable and dynamic environment that is greatly influenced by diurnal tidal fluctuations, particularly during high spring tides, and major precipitation events and subsequent storm water runoff. It appeared that seasonal variations observed in the lower Tijuana River valley did not influence the hydrologic nature of the estuary.

SEMINAR - Shuo Ma

2008-10-09T20:59:00.000-07:00

A Physical Model for Widespread Near-Surface and Fault Zone Damage Induced by Earthquakes

Shuo Ma
Department of Geological Sciences
San Diego State University

Wednesday, October 15th, 2008

Seismic observations indicate that material velocities at shallow depths decrease over a large area after large earthquakes. The reductions are widespread, and occur at distances of up to several source dimensions. A persistent low-velocity fault zone has also been documented extensively from seismic and geodetic observations, in which the velocity drops further after large earthquakes. Dynamic stresses carried by seismic waves in the near surface or accompanying rupture at depth in the fault zone, are thought to create these velocity reductions by causing material damage. However, a rigorous physical interpretation as to why modest dynamic stresses can cause widespread near-surface damage, and why fault damage zones form, is lacking. By using a Drucker-Prager yielding criterion to simulate dynamic rupture propagation on a vertical strike-slip fault, I show that the widespread near-surface damage is caused by material yielding induced by seismic waves under the low confining pressure. Because the confining pressure increases with depth, materials yield more easily near the surface. The yielding zone at depth is narrowly confined near the fault, but its thickness broadens dramatically near the surface, forming a ‘flower-like’ damage zone, which is commonly observed in the geologic record. The fault zone damage at depth is induced by the large dynamic stress associated with the rupture front, while is induced by strong seismic waves ahead of the rupture front near the Earth’s surface. These results have important implications for the formation and evolution of fault zones, and possibly for the dynamic triggering of earthquakes as well.

SEMINAR - Chun-Ta Lai

2008-10-01T20:09:00.000-07:00

Use of stable isotopes in studies of forest-atmosphere H2O and CO2 exchange

Chun-Ta Lai
Department of Biology
San Diego State University

Wednesday, October 8th, 2008

Stable oxygen (18O/16O) and hydrogen (2H/1H) isotopes at natural abundance levels are useful tracers for studying water and carbon cycles in terrestrial ecosystems. Atmospheric water vapor contains fewer amounts of heavier water isotopes (2H and 18O) relative to the source water. In the case of surface water loss via vegetation (transpiration), this preferential loss of lighter water isotopologues result in enriched 2H and 18O contents in leaf water. Meanwhile, CO2 that diffuses into leaf intercellular space and later out of stomata become labeled by this enriched 18O signature. Scientists have used this labile 18O signal in studies of global carbon cycles and paleoclimatic reconstruction. Improving our understanding of leaf water 18O enrichment allows for the development of better process-based models to investigate biosphere-atmosphere water and carbon dioxide exchange processes spanning from ecosystem to global scales. Discussions will be emphasized on how biotic and abiotic factors influence diurnal and vertical variations of 2H and 18O in leaf water and water vapor in forest air.

SEMINAR - J. Fred Bair

2008-09-24T20:11:00.000-07:00

Development Geology of the Antelope Shale: Section 1Y, Cymric Field, San Joaquin Valley, California

J. Fred Bair
MWSS Asset Development TeamChevron North America Exploration and Production Company

Wednesday, October 1st, 2008

The Antelope Shale reservoir in Section 1Y, Cymric Field, San Joaquin Valley, California is one of Chevron’s key assets. The reservoir is a Miocene Age member of the Monterey Formation composed of Opal A (amorphous), Opal CT (cristobalite, tridimite) and Quartz phase diatomaceous deep water sediments. The Antelope Shale has an anomalously high average porosity of 58%, high initial oil saturations of up to 60%, and low permeabilities of 3 millidarcys. Development geology skills required to process this complex reservoir and involve: obtaining, analyzing, and evaluating open hole well logs; structural mapping and correlation; fracture mapping using development geophysics; and an understanding of the diagenetic process.

SEMINAR - Clive Dorman

2008-09-18T12:08:00.000-07:00

Tidal Bore on the Severn River

Clive Dorman
Department of Geological Sciences
San Diego State University

Wednesday, September 24th, 2008

Tides progress up the Severn River in SW England as a tidal bore moving faster than 6 m/s. During spring tides, the leading edge of the bore can be up to 2 m high, taking more than an hour to travel from the lower portion of the river to past Gloucester. This is sufficient to attract surfers from around the world. The North Atlantic amphidromic system interacts with the broad continental shelf around the U.K. to produce a complicated field of large tidal ranges. This forces a twice daily standing wave along the Bristol Channel, that further amplifies the tidal range toward the back of the Channel and the mouth of the Severn River. High tide is effectively a very long wave that moves against the out bound Severn River flow, so the leading edge sharpens, forming a bore. The shape of the leading edge varies between a smooth wave and a breaking wave. The presentation will include two short videos of the bore.

SEMINAR - Norrie Robbins

2008-09-15T09:39:00.001-07:00

Utilization of Geological Techniques to Help Solve an Archaeological Puzzle: When Did People Arrive in North America?

Eleanora (Norrie) Robbins
Department of Geological Sciences
San Diego State University

Wednesday, September 17th, 2008

Knut Fladmark hypothesized that as soon as boat technology was developed 40,000 years ago, people probably traveled the oceans. The 40,000-year-ago shoreline is now below 150-160 ft (50 m) of water and an unknown thickness of sediment. So evidence for boat transport by maritime people would be under the today’s oceans. Geological data could provide locations of specific paleoshorelines and general sedimentation rates. Palynological data from cores could provide information about introduction of medicinal and food plants from distant sources. Underwater geophysical techniques such as magnetic mapping, resistivity methods, seismic profiling and ground penetrating radar might be useful too.
An interesting idea about changing shorelines was successfully tested by Thomas Dillehay and Ruth Gruhn at the Monte Verde cave sites in Chile. They suggested searching for onshore caves along narrow continental shelves. Submarine canyons also should be searched because they are often fracture zones. Such places not only might have now-submerged caves but are also subjected to periodic sediment removal. So, submarine canyons might be good places for deep SCUBA divers to search for caves and buried artifacts.
It is easy to envision early maritime people, staying by the paleo-shoreline, taking advantage of abundant marine food sources. Through time, descendents would have followed the rise and fall of sea level. At the time of peak glaciation 21,000 years ago, the entire continental shelf was exposed. Then as sea level rose upon glacial melting, village sites would have moved shoreward accordingly. The 8,000-year-ago shoreline is now below 1.5-6 m (5-20 ft) of water. Indeed, large, heavy artifacts from a submerged village of that age are often seen by divers especially near the La Jolla Beach and Tennis Club. Around 7,000 years ago, an episode of intense erosion occurred, which would have reduced water clarity, affected marine animal distribution, and forced people toward onshore sources of reliable food.
Other evidence for early marine travel might be in the creation songs of today’s coastal indigenous people. Many songs tell of creation from the ocean and mention boats. One even tells of the arrival of the “new people” who hunted big game. The creation songs may help prove that the earliest ancestors arrived here very, very long ago by boat. Geologists are needed to help lead the search.

Dr. Eleanora (Norrie) Robbins is a paleo-palynologist, former student of Paul S. Martin (“Pleistocene Extinctions”), and retired from the U.S. Geological Survey in Reston after 34 years. She is now adjunct faculty in the Dept. of Geological Sciences at SDSU. She mapped for Louis Leakey in 1965 at the Chelles-Acheulian Olorgesailie

Thesis Defense - Fall 2008 - Ben Slotnick

2008-09-04T22:19:00.000-07:00

Biotic response of Tethyan bathyal ostracodes through the Eocene-Oligocene Transition from the Massignano Composite Stratotype Section (east central Italy)

Ben Slotnick
M.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Stephen Schellenberg

Monday, September 8th, 2008

ABSTRACT
The Eocene-Oligocene Transition (EOT) is marked by a double-stepped ~1.3‰ positive excursion in d18O over an ~300 kyr interval (i.e., Oi-1; Miller et al., 1991; Zachos et al., 1996; Coxall et al., 2005) and a deepening of the calcium compensation depth (CCD) interpreted to represent marked Antarctic glaciation and global ocean-atmosphere cooling. A ~0.5 m (~55-70 kyr) resolution ostracode faunal study of the Massicore, drilled adjacent to and up-section from the Italian Massignano quarry stratotype section that contains the Eocene-Oligocene GSSP (i.e., base of the Priabonian stage), revealed two transient increases in Krithe and decreases in faunal evenness, enthalpy, eH, and Simpson’s Index that lag two surface water cooling pulses based on a dinocyst-based sea surface temperature (DSST) proxy (van Mourik et al., in prep). These transient ostracode faunal changes may reflect changing physico-chemical water properties, increased sedimentation rates, variable food availability in the benthos, and/or intensifying thermohaline circulation from the Indian or Atlantic Ocean through the paleotethyan seaway. Ordination and cluster analyses also show minor faunal differences during times of relatively cold and warm surface waters based on the DSST proxy. Comparisons made between these Massicore ostracode data and re-analyzed Massignano Quarry ostracode data from Dall’Antonia et al. (2003) revealed major similarites (i.e., similar relative abundances among common taxa where both studies overlap) making it practical for us to combine both records in order to provide a more complete Tethyan ostracode record through the broader EOT and spanning Oi-1 at the stratotype locality.

New Faculty - Shuo Ma

2008-08-29T21:04:00.000-07:00

Shuo Ma

Ph.D. (UC Santa Barbara 2006), studies the understanding of earthquake source physics central to earthquake seismology. His research focuses on numerical simulation of earthquake source dynamics, wave propagation in complex media and ground motion estimation. He uses field observations, e.g., ground motion, GPS, seismicity and off-fault damage, among others, to constrain features of his simulations, such as rupture initiation, propagation and healing. He is also interested in longer term crustal deformation during inter-seismic periods. Ma’s research accomplishments include: assessment of radiated seismic energy from dynamic rupture models, effects of large-scale surface topography on ground motions, dynamic modeling of the 2004 Parkfield earthquake and versatile finite element code for static and dynamic earth quake modeling.

Research Interests
Earthquake source mechanics, strong-motion seismology, seismic wave propagation in complex media, crustal deformation, fault zone damage, and seismic interferometry.

Publications

Ma, S., G. A. Prieto, and G. C. Beroza, Testing community velocity models for southern California using the ambient seismic field, Bulletin of the Seismological Society of America, in press.
Sleep, N. H., and S. Ma (2008), Production of brief extreme ground acceleration pulses by nonlinear mechanisms in the shallow subsurface, Geochemistry, Geophysics, Geosystems, 9, Q03008, doi:10.1029/2007GC001863. pdf
Ma, S., and G. C. Beroza (2008), Rupture dynamics on a bi-material interface for dipping faults, Bulletin of the Seismological Society of America, 98, 1642-1658, doi:10.1785/0120070201. pdf
Ma, S., S. Custodio, R. J. Archuleta, and P. Liu (2008), Dynamic modeling of the Mw 6.0 Parkfield, California, earthquake, Journal of Geophysical Research, 113, B02301,doi:10.1029/2007JB005216. pdf
O'Connell, D.R.H., S. Ma, and R. J. Archuleta (2007), Influence of dip and velocity heterogeneity on reverse- and normal-faulting rupture dynamics and near-fault ground motions, Bulletin of the Seismological Society of America, 97, 1970-1989, doi: 10.1785/0120070040. pdf
Ma, S., R. J. Archuleta, and M. T. Page (2007), Effects of large-scale surface topography on ground motions, as demonstrated by a study of the San Gabriel Mountains, Los Angeles, California, Bulletin of the Seismological Society of America, 97, 2066-2079, doi: 10.1785/0120070040. pdf
Ma, S. (2006), Using the dynamics of faulting to explore radiated seismic energy and ground motion, Ph.D dissertation, University of California, Santa Barbara. pdf
Ma, S. and P. Liu (2006), Modeling of the perfectly matched layer absorbing boundaries and intrinsic attenuation in explicit finite-element methods, Bulletin of the Seismological Society of America, 96, 1779-1794, doi: 10.1785/0120050219. pdf
Ma, S. and R. J. Archuleta (2006), Radiated seismic energy based on dynamic rupture models of faulting, Journal of Geophysical Research, 111, B05315, doi:10.1029/2005JB004055. pdf Ma, S., R. J. Archuleta, and P. Liu (2004), Hybrid modeling of elastic P-SV wave motion: A combined finite-element and staggered-grid finite difference approach, Bulletin of the Seismological Society of America, 94, 1557-1563. pdf
Zhang, R., S. Ma, and S. Hartzell (2003), Signatures of the seismic source in EMD-based characterization of the 1994 Northridge, California, earthquake recordings, Bulletin of the Seismological Society of America, 93, 501-518. pdf
Zhang, R., S. Ma, E. Safak, and S. Hartzell (2003), Hilbert-Huang transform analysis of dynamic and earthquake motion recordings, Journal of Engineering Mechanics, 129,861-875. pdf
Cao, B., Q. Luo, S. Ma, and J. Liu (2002), Seismic response of Dakai subway station during the 1994 Kobe, Japan, earthquake, Earthquake Engineering and Engineering Vibration, 22,102-107. (In Chinese)
Ma, S., and Q. Luo (1998), Damage to ports and river embankments caused by the 1994 Kobe, Japan, earthquake and lessons learned from it, Journal of Catastrophology, 13, 47-50. (In Chinese)