New Faculty - Shuo Ma

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)

Thesis Defense - Fall 2008 - Cameron Campbell

Identification of a New Class of Deformation Bands

Cameron Campbell
M.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Gary Girty

Thursday, August 14th, 2008

ABSTRACT
I describe for the first time the occurrence of deformation bands within a strike-slip tectonic setting within the Ocotillo Conglomerate, located in the San Felipe Hills, southern California, U.S.A. A conjugate set of over 35 strike-slip faults occur within the study area. They commonly are comprised of a fault core consisting of a network of coalesced deformation bands, and a surrounding damage zone, several meters thick, of more widely spaced deformation bands. In order to characterize the textural, physical, and chemical attributions of deformation band development, twenty-four samples of a distinctive marker bed transected by multiple deformation bands, and twelve samples of deformation bands were collected for detailed laboratory study. Average grain and bulk densities for the marker bed are relatively low (~2.67 and 1.6 g/cm3 respectively). In contrast, grain and bulk densities for deformation bands are high (~2.74 and 2.1 g/cm3 respectively). Average porosity for the deformation bands is low (22.9%) in relation to the marker bed (40.1%). Relative to the framework composition volumetric strain results show a loss of -24.7% +/-7.1% for deformation band samples. Point counts and petrographic work of thin sections, reveal a reduction in pore space, abundant evidence for grain fragmentation and a reduction in grain size, and an increase in matrix. The matrix of deformation bands is composed mostly of illite and smectite-rich I/S expandable clays. Evidence presented herein indicates that shear bands within the Ocotillo Congl omerate are cataclastic in character and likely formed at depths ranging from 2.5-4.0 km during development of a conjugate strike-slip fault system. However, they are not the result of compaction during deep burial, and thus they represent a new class of deformation bands.