New Publication - Aaron Meltzner & Tom Rockwell

Bulletin of the Seismological Society of America, December 2006, Vol. 96, Issue 6, pp. 2304-2328

Recent and long-term behavior of the Brawley fault zone, Imperial Valley, California; an escalation in slip rate?
Meltzner, Aron J. (San Diego State University, Department of Geological Sciences, San Diego, CA, United States); Rockwell, Thomas K.; Owen, Lewis A.

ABSTRACT

The Brawley fault zone (BFZ) and the Brawley Seismic Zone constitute the principal transfer zone accommodating strain between the San Andreas and Imperial faults in southernmost California. The BFZ ruptured along with the Imperial fault in the 1940 M (sub w) 6.9 and the 1979 M (sub w) 6.4 earthquakes, although in each case only minor slip apparently occurred on the BFZ; several other episodes of slip and creep have been documented on the BFZ historically. Until this study, it has been unclear whether the past few decades reflect average behavior of the fault. Two trenches were opened and a series of auger holes were bored across three strands of the BFZ at Harris Road to compare the amount of slip observed historically with the displacements observed in the paleoseismic record. Evidence is presented, across the westernmost strand of the BFZ and across the entire BFZ at Harris Road, to show that both the average vertical slip rate observed in modern times (since 1970) and the vertical creep rate (excluding coseismic slip) observed during the 1970s are significantly higher than the long-term average. Across the westernmost strand, the long- term vertical rate is 1.2 (+1.5/-0.5) mm/yr, and the average rate since about A.D. 1710 is determined to be no greater than 2.0 mm/yr; in contrast, the average vertical rate between 1970 and 2004 across that strand was at least 4.3 mm/yr, and the 1970s vertical aseismic creep rate was 10 mm/yr. Likewise, across the entire BFZ, the long-term vertical rate is 2.8 (+4.1/-1.4) mm/yr, whereas the rate between 1970 and 2004 was at least 7.2 mm/yr, and the 1970s aseismic creep rate was 10 mm/yr. The long-term strike-slip rate cannot be determined across any strands of the BFZ but may be significant. In contrast to the commonly accepted higher sedimentation rates inferred for the entire Imperial Valley, we find that the average sedimentation rate on the downthrown side of the BFZ adjacent to Mesquite Basin, in the millennium preceding the onset of agricultural influences, was at most 3.5 mm/yr. Finally, a creep event occurred on the BFZ during our study in 2002 and is documented herein.

Southern Salton Trough deltaic system, based on DEM imagery. Color contours indicate elevation; each color band represents a 5- to 10-m change in elevation. Sections of some contours are highlighted with thin black lines for improved visibility. The band labeled “12m” is the contour at an elevation of 12 m above mean sea level, which represents the highstand shoreline of Lake Cahuilla. Note the location of the modern delta, which is interpreted to have formed initially in response to the 1905– 1907 filling of the Salton Sea; slow retreat of the lake combined with regular flow of the New and Alamo Rivers has built this modern delta that is prograding into the Salton Sea. In addition to the modern delta, four prehistoric delta lobes have been interpreted on this DEM: deltas N1 and N2 on the New River, and deltas A1 and A2 on the Alamo River. Main faults are mapped in black. SMF, Superstition Mountain fault; SHF, Superstition Hills fault. Modified from Ragona (2003). ( E A color version of this figure is available in the electronic edition of BSSA.)

Full Text (pdf)

Tidal Bore on the Dordogne River

Alumni Banquet presentation by honoree Dr. Clive Dorman

Video from Clive's trip to France

SEMINAR - Lee T. Billingsley

Lee Billingsley received a B.S. in Geology from Texas A&M in 1975, an M.S. in Geology from the Colorado School of Mines in 1977, and a Ph.D. in Geology from Texas A&M in 1983. He began his oil and gas career in 1976 with Tenneco Oil Company in Denver, and later worked with American Quasar Petroleum (Denver) and Monterrey Petroleum Corporation (San Antonio). From 1983-1998, he was President and Founder of Sandia Oil & Gas Corporation, until joining Abraxas Petroleum Corporation in 1998. He is currently Vice-President of Exploration. Dr. Billingsley is a member of many regional and national professional societies, and he has received numerous awards including the AAPG Distinguished Service Award (1997) and Certificate of Merit (1999), as well as the GCAGS Distinguished Service Award (1998). He served as President of the South Texas Geological Society (1985-86) and as General Chairman of the 2004 GCAGS Convention in San Antonio. Within AAPG, he has held several positions including Treasurer, member of House of Delegates, Associate Editor of the Bulletin, and Division of Professional Affairs Secretary. Currently, he is AAPG President (2006-2007).

Lee's seminar title: "Exploiting the Devonian Reservoir in Oates SW Area, Western Delaware Basin, Texas"; Wednesday the 28th of February 2007

Abstract
The Oates SW field area is located in southwestern Pecos County, Texas, and it is in the southwestern portion of the Delaware basin. The dominant producing reservoir in the area is simply called Devonian, but it is probably Devonian-aged chert in the Thirtyone Formation. Regional structure is NE dip into the basin with some NW-SE trending faults. The Oates SW area is flanked by large structural closures that have produced gas from the Devonian and adjacent reservoirs. These fields include: Perry Bass, 26 BCF from nine wells; Oates NE 266 BCF from 25 wells, and Pikes Peak, 48 BCF from eight wells.
In contrast to surrounding fields, Oates SW consists of four small structural closures that vary in size from about 320 to 1280 acres. Abraxas acquired 3-D seismic data to refine the structural interpretation and guide potential horizontal well bores. Each closure has from one to three vertical wells, and the wells produced from 0.2 to 2.4 BCFG each from the Devonian chert. Production from each vertical well near the top of closures roughly correlates to Devonian reservoir quality determined from log analysis. However, a comparison between calculated original gas-in-place and actual production for each closure indicates a relatively low recovery factor. All the vertical wells exhibited high rates of water production late in their productive history.
Abraxas has drilled three horizontal well bores within the Devonian chert on separate closures. Results span the spectrum of potential outcomes. The best well has produced at a constant rate of 8 MMCFD and the worst well only makes 150 MCFD. The third well is a re-entry of a vertical well, which had produced 1.8 BCFG. Abraxas drilled horizontally within the Devonian chert. Initially, the well produced 100% water, but gas rates eventually increased. Currently, the well produces at relatively constant rates of 700 MCFD and 4000 BWPD. The source of the water production is unknown. It could be from: 1) near well bore, but not from the Devonian interval, 2) micro-fractures within the Devonian, which are connected to deeper water sources like the Ellenburger, or 3) near well bore water coned upward during production form the vertical well bore.
Detailed correlation of logs indicates an unconformity at the top of the Devonian chert. Consequently, the porous Devonian chert interval is thinner in structurally high wells. This interpretation may explain the variable reservoir quality of the three wells, based on the projected trajectory of the horizontal well bores.
As with other horizontal Devonian chert fields, results are highly variable from well-to-well. Overall the economics of the play in Oates SW have been favorable, but much still needs to be learned in order to repeat the success.

SEMINAR - Ross Stein

Biography
My research focuses upon how earthquakes interact through the transfer of stress. Examples of such interaction include the progression of mainshocks along a fault, aftershocks, seismic quiesence, and earthquake clustering. My collaborators and I are interested in how one earthquake can promote subsequent shocks at some sites and inhibit them in others.
This work is driven by an attempt to deepen our understanding of the physics of earthquakes, and a desire to develop a new way to make probabilistic hazard assessments. Our tools are seismology, geophysics, elasticity theory, structural geology, and geomorphology.
In addition, I study the deformation of the earth's surface associated with earthquakes, fault creep, and volcanic processes. This work seeks to infer rupture and fault geometry, and to understand the relationship between earthquake deformation and geologic structures. Our tools are classical and space geodesy. Key interests are blind thrust faults, high-angle normal faults, and magmatic inflation and collapse.
My work is currently funded by a Cooperative R&D Agreement with Swiss Re, the world's second largest insurance company; and through a series of research grants from NASA. My first R&D project with Swiss Re was a study of the earthquake threat to Istanbul in the wake of the 1999 Izmit shock; the current Swiss Re project assesses the earthquake hazard for Tokyo, and with participation by several leading Japanese scientists. A 1996-2001 R&D project earthquake hazards in the San Francisco Bay area was carried out with PG&E. Other recent studies were funded by U.S. Office of Foreign Disaster Assistance and FEMA.
Over the past several years, I have participated in documentary films, including 'Killer Quake' (NOVA, 1995), 'Great Quakes: Turkey' (Discovery Channel, 2001), 'Earthquake Storms' (BBC, 2003), and an IMAX film, 'Forces of Nature' (National Geographic), which wass released in summer 2004. Click here to see an article about 'Forces of Nature' in the Mercury News.

Stein's seminar title: "Truth & Consequences: Assessing the Earthquake Threat to Tokyo"; Wednesday the 28th of February 2007

Department Spring Fieldtrip - Death Valley

Experience the geologic wonders of Death Valley - one of the most dramatic geological landscapes on earth! This active rift basin has all the classic components; active fault scarps and fault-block mountains, alluvial fans building out, internal drainage and extensive salt flats, recent volcanic activity, and modern dune fields. This years spring trip will be a four day adventure.

Why Death Valley?

Death Valley forms part of the Basin and Range Province – a region stretched to the breaking point by tectonic forces.
It is similar to other basins of the region, but is unique because it is the lowest, hottest, driest location in the western hemisphere.

Death Valley is an active rift basin with all the classic components; active fault scarps and fault-block mountains, alluvial fans building out, internal drainage and extensive salt flats, volcanic activity, and modern dune fields.

The awesome splendor of Zabriskie Point

Death Valley salt pan – the remains of a Pleistocene lake that was once filled the valley over 600 feet deep!


Devil’s Golf Course – the inhospitable floor of Death Valley salt pan!

LEARN ABOUT THE HERITAGE
The Borax twenty mule team is one of the most memorable icons of the American West, and of the pioneers who transformed its mineral wealth into a foundation of modern industry throughout the world.
The saga of the twenty mule team began more than a century ago in the arid deserts of California's Death Valley.

Although rainfall is scarce, water is the creative force that builds Death Valley's alluvial fans.

Mesquite Dunes
SARATOGA SPRNGS: It's hard to believe that these lush ponds are found within the parched boundaries of Death Valley National Park.

This rare desert wetland supports a rich community of plants and animals. Some like the DESERT PUPFISH, are found nowhere else in the world.

SEMINAR - Vic Camp

Dr. Vic Camp received his Phd at Washington State University. He Worked for the USGS, followed by 10 years overseas as an Assistant Professor in West Africa (Univesity of Ibadan) and as a field geologist in Iran and Saudi Arabia. Became an Adjunct Professor at SDSU in 1988, and a full-time lecturer at SDSU in 1993. Vic's research interests have largely centered around the tectonomagmatic evolution of continental volcanic provinces. These include ocean closure generating a Mesozoic continental suture zone in the Neo-Tethyan belt of eastern Iran, terrane accretion in the early Proterozoic mobile belts of the Arabian Shield, mantle upwelling in the Cenozoic harrat volcanic province of western Saudi Arabia, and most recently, plume emplacement in the Columbia River Basalt province and the northern Basin and Range.

Vic will lecture on "A Plume-induced Delamination Model for the Enigmatic Grande Ronde Basalts" Wednesday the 21st of February 2007

Abstract

Many workers attribute the great volume and chemical diversity of continental flood basalts to the rapid rise and melting of deep-seated mantle plumes, whereas others suggest that a plume is not necessary, and prefer a model of rapid melting associated with the delamination of mantle and lower crust. These competing models, however, are not mutually exclusive. Here, I will describe the Columbia River flood basalts as a case study, demonstrating that the tectonic history and chemical progression of the lava sequence are consistent with plume-induced delamination of thin Phanerozoic lithosphere juxtaposed against a thick Precambrian cratonic boundary. Such a model may provide a new, realistic mechanism for generating the chemical diversity and high magma supply rates of continental flood basalts in similar tectonic settings.

SEMINAR - Dogan Seber

Dogan Seber is Director of the DAKS Geoinformatics Lab at the as the San Diego Supercomputer Center. Seber is also serving as project manager on the NSF large Information Technology Research project, GEON, for Geosciences Network, for which SDSC is coordinating IT research. Seber received his undergraduate degree in geophysics from the Istanbul Technical University in his native Turkey, and his Ph.D. in seismology and geophysics from Cornell. Seber came to SDSC in 2003 from Cornell University, where he established and directed the Earth Science Information Systems Program in the Institute for the Study of the Continents, a project to develop a comprehensive geological and geophysical digital database system primarily for the Middle East, North Africa, and the United States. One of the largest programs of its kind in the nation, the interactive Web-based system (http://atlas.geo.cornell.edu/) serves hundreds of users daily ranging from geoscientists to elementary school students. Seber and other "early adopters" of geoinformatics in the GEON collaboration have a vision of a geosciences cyberinfrastructure that will help scientists solve earth science problems faster and on a larger scale, ultimately enabling them to encompass the entire Earth system. source: SDSC

Dogan will lecture on the "Enabling Discoveries in the Earth Sciences Through the Geosciences Network (GEON)"; Wednesday the 14th of February 2007

Abstract
Taking advantage of the state-of-the-art information technology resources GEON is building a cyberinfrastructure to enable data sharing, semantic data integration, high-end computations and 4D visualization in easy-to-use web-based environments. The GEON Network currently allows users to search and register Earth science resources such as data sets, software applications and ontologies. Portal based access mechanisms enable developers to built dynamic user interfaces to conduct advanced processing and modeling efforts across distributed computers and supercomputers. Researchers and educators can access the networked resources through the GEON portal to conduct better and more comprehensive science and educational studies. For example, the SYNSEIS portlet in GEON enables users to access in near-real time seismic waveforms from the IRIS Data Management Center, easily build a 3D geologic model within the area of the seismic station(s) and the epicenter and perform a 3D synthetic seismogram analysis to understand the lithospheric structure and earthquake source parameters for any given earthquake in the US. Similarly, GEON's workbench area enables users to create their own work environment and copy, visualize and analyze any data sets within the network, and create subsets of the data sets for their own purposes. Since all these resources are built as part of a Service-oriented Architecture (SOA), they are also used in other development platforms. Developments in the area of semantic integration of the networked datasets continue to advance and prototype studies can be accessed via the GEON portal at www.geongrid.org

SEMINAR - Leonard J. Srnka

Dr. Leonard J. Srnka received a B.S. in Engineering Science from Purdue University in 1968, graduating summa cum laude. In 1974, he received his PhD in Physics from the University of Newcastle upon Tyne, United Kingdom and from Corpus Christi College, Oxford University, United Kingdom (1970-1973), where he was a Marshall Scholar. Leonard spent his early career working for the NASA Lunar Science Institute as a Postdoctoral Fellow (1974-1976) and as a Staff Scientist (1976-1979) where he researched on the origins and evolution of lunar and planetary electromagnetism. The latter part of his career has been spent working at the ExxonMobil Corporation. From 1979-1993 he was project leader and supervisor with assignments in electromagnetic methods, seismic modeling and inversion, and borehole geophysics. He was a supervisor for gravity, magnetics, and remote sensing research and applications (1993-1998). From 1998 to present, Len has been the project leader for land and marine electromagnetic technology, and serves as a member of the senior technical staff. He championed the Remote Reservoir Resistivity Mapping (“R3M”) breakthrough research project for upstream applications. He has been the Chief Scientist on numerous marine CSEM surveys offshore Europe and West Africa in 2001-2003. Leonard has special interests in marine MT and CSEM acquisition technology, 3D modeling, data interpretation, and imaging/inversion. He has twenty-six refereed publications and numerous patents issued and pending. source: SEG

Leonard will lecture on the "Illuminating Reservoirs with Electromagnetics"; Wednesday the 7th of February 2007