Annual Meeting - SCEC.org

Report | SCEC Research Accomplishments
Another advance has been the application of multiple 10Be surface exposure dates to model the onset of fragility of
precariously balanced rocks (Figure 14), recently published in Quaternary Geochronology (Balco et al., 2011).
References
Balco, G., Purvance, M., and Rood, D. (2011) Exposure dating of precariously balanced rocks, Quaternary Geochronology, v. 6,
p. 295-303.
Behr, W., Rood, D., Fletcher, K., Guzman, N., Finkel, R., Hanks, T., Hudnut, K., Kendrick, K., Platt, J., Sharp, W., Weldon, R.,
and Yule, J. (2010) Uncertainties in slip-rate estimates for the Mission Creek strand of the southern San Andreas fault at
Biskra Palms Oasis, southern California, Geological Society of America Bulletin, vol. 122, p. 1360-1377.
Fletcher, K., Sharp, W., Kendrick, K., Behr, W., Hudnut, K., and Hanks, T. (2010) 230Th/U dating of a late Pleistocene alluvial
fan along the southern San Andreas fault, Geological Society of America Bulletin, v. 122, p. 1347-1359.
Oskin, M., Arrowsmith, J., Hinojosa, A., Elliott, A., Fletcher, M., Fielding, E., Gold, P., Gonzalez, J, Hudnut, K., Liu-Zheng, J.,
and Teran, O., (2010) Near-field deformation from the El Mayor-Cucapah earthquake quantified with airborne LiDAR,
submitted to Nature Geoscience.
Shelef, E., and Oskin, M., (2010) Deformation processes adjacent to active faults: Examples from Eastern California, Journal of
Geophysical Research – Solid Earth, Vol. 115, B05308, 24 pp., doi:10.1029/2009JB006289.
Disciplinary Activities
Within the SCEC structure, the focus groups are responsible for coordinating interdisciplinary activities in six major areas of
research: Unified Structural Representation, Fault and Rupture Mechanics, Crustal Deformation Modeling, Lithospheric Architecture
and Dynamics, Earthquake Forecasting and Predictability, Ground Motion Prediction, and Seismic Hazard and Risk Analysis. The
following sections summarize the year’s activities in each of these areas.
Unified Structural Representation
The Unified Structural Representation (USR) Focus Area develops models of crust and upper mantle structure in California
for use in a wide range of SCEC science, including strong ground motion prediction, earthquake hazards assessment, and fault
systems analysis. These efforts include the development of Community Velocity Models (CVM-S, CVM-SI, & CVM-H) and
Community Fault Models (CFM, CFM-R, SCFM), which together comprise a USR. In partnership with other working groups
in SCEC, the USR Focus Area also helps support the evaluation and improvement of these models through ground motions
simulations, 3D waveform tomography, earthquake relocations, and fault systems modeling.
1. This past year’s accomplishments include:
2. Development of new versions of the SCEC Community Velocity Model (CVM-H 11.2 and 11.9), which include new
representations of the San Bernardino and offshore Santa Maria basins;
3. Development of a new version of the SCEC Community Velocity Model (CVM-SI), which includes perturbations to
an existing model (CVM-S) as a result of iterative inversion simulations by Chen et al (2011) and Lee et al (2010). A
similarly refined CVM-H model was released as versions 11.2 to 11.9, and is currently being updated.
4. Support for the development of the statewide
UCVM by the SCEC CME group, which includes
these latest southern California model versions
(CVM-S, CVM-SI, CVM-H) along with other
alternative and complimentary regional velocity
models in a common delivery platform.
5. Implementation of a new CVM evaluation system by
the SCEC CME that uses wave propagation
simulations of moderate magnitude historical
earthquakes and goodness-of-fit (GOF)
measurements that compare simulated and
52 | Southern California Earthquake Center
Figure 15. Map of difference in Vs between CVM-SI i5-i0 and CVM-S
4.0 at depth 0m (after Chen et al., 2011; Lee et al., 2010).