Lin, Guoqing and Thurber, Clifford H. and Zhang, Haijiang and Hauksson, Egill and Shearer, Peter M. and Waldhauser, Felix and Brocher, Thomas M. and Hardebeck, Jeanne (2010) A California Statewide Three-Dimensional Seismic Velocity Model from Both Absolute and Differential Times. Bulletin of the Seismological Society of America, 100 (1). pp. 225-240. ISSN 0037-1106 http://resolver.caltech.edu/CaltechAUTHORS:20100303-135921624
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We obtain a seismic velocity model of the California crust and uppermost mantle using a regional-scale double-difference tomography algorithm. We begin by using absolute arrival-time picks to solve for a coarse three-dimensional (3D) P velocity (V_P) model with a uniform 30 km horizontal node spacing, which we then use as the starting model for a finer-scale inversion using double-difference tomography applied to absolute and differential pick times. For computational reasons, we split the state into 5 subregions with a grid spacing of 10 to 20 km and assemble our final statewide V_P model by stitching together these local models. We also solve for a statewide S-wave model using S picks from both the Southern California Seismic Network and USArray, assuming a starting model based on the VP results and a V_P/V_S ratio of 1.732. Our new model has improved areal coverage compared with previous models, extending 570 km in the SW–NE direction and 1320 km in the NW–SE direction. It also extends to greater depth due to the inclusion of substantial data at large epicentral distances. Our V_P model generally agrees with previous separate regional models for northern and southern California, but we also observe some new features, such as high-velocity anomalies at shallow depths in the Klamath Mountains and Mount Shasta area, somewhat slow velocities in the northern Coast Ranges, and slow anomalies beneath the Sierra Nevada at midcrustal and greater depths. This model can be applied to a variety of regional-scale studies in California, such as developing a unified statewide earthquake location catalog and performing regional waveform modeling.
|Additional Information:||© 2010 Seismological Society of America. We thank the U.S. Geological Survey (USGS) and Caltech staff for maintaining the NCSN and SCSN, and the IRIS Data Management Center for making USArray data available. R. Catchings,C. Evangelidis, A. Frankel, G. Fuis, S. Hartzell, W. Kohler, A. Lindh, J. Murphy, D. O’Connell, and T. Parsons contributed first-arrival times and receiver and source locations for active-source experiments in the study area. We thank W.-X. Du for his effort to assemble the northern California active-source data set into a consistent form and Y. Yang for providing his ambient noise tomography model. This work is supported by the National Earthquake Hazards Reduction program, under USGS awards 07HQGR0038, 07HQGR0045, 07HQGR0047, 07HQGR0050, 08HQGR0032, 08HQGR0039, 08HQGR0042 and 08HQGR0045, and the National Mapping Programs of the USGS. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. government.|
|Subject Keywords:||body waves; California; Cascade Range; crust; data management; depth; earthquakes; elastic waves; information management; Klamath Mountains; mantle; Mount Shasta; P-waves; S-waves; seismic waves; Siskiyou County California; three-dimensional models; tomography; United States; upper mantle; velocity; velocity structure|
|Official Citation:||Guoqing Lin, Clifford H. Thurber, Haijiang Zhang, Egill Hauksson, Peter M. Shearer, Felix Waldhauser, Thomas M. Brocher, and Jeanne Hardebeck A California statewide three-dimensional seismic velocity model from both absolute and differential times Bulletin of the Seismological Society of America (February 2010), 100(1):225-240|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||11 Mar 2010 21:43|
|Last Modified:||26 Dec 2012 11:49|
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