地震学报（英文版）2003，Vol.16Issue(6)：577-587,11.
P-wave tomography of crust and upper mantle under Southern California: Influence of topography of Moho discontinuity
P-wave tomography of crust and upper mantle under Southern California: Influence of topography of Moho discontinuity
摘要
Abstract
We use 146 422 P-wave arrival times from 6 347 local earthquakes recorded by the Southern California SeismicNetwork to determine a detailed three-dimensional P-wave velocity structure at 0～35 km depth. We have takeninto account the Moho depth variations, which were obtained by seismological methods. Checkerboard tests sug-gest that our inversion results are reliable. Our models provide new information on regional geological structuresof Southern California. At shallow depths P-wave velocity structure correlates with surface geological features andexpresses well variations of surface topography of the mountains and basins. The velocity structure at each layer ischaracterized by block structures bounded by large faults. Ventura Basin, Los Angeles Basin, Mojave Desert, Pen-insular Ranges, San Joaquin Valley, Sierra Nevada, and Salton Trough show respectively all-round block. SanAndreas Fault becomes an obvious boundary of the region. To its southwest, the velocity is higher, and there arestrong heterogeneity and deeper seismicity; but to its northeast, the velocity is lower and shows less variation thanto the southwest, the seismicity is shallower. To investigate the effect of the Moho geometry we conducted inver-sions for two cases: one for flat Moho geometry, another for a Moho with lateral depth variations. We found thatthe topography of the Moho greatly affects the velocity structure of the middle and lower crust. When the Mohotopography is considered, a more reasonable tomographic result can be obtained and the resulting 3-D velocitymodel fits the data better.关键词
Southern California/Moho discontinuity/3-D P-wave velocity structure/block feature/seismicityKey words
Southern California/Moho discontinuity/3-D P-wave velocity structure/block feature/seismicity分类
天文与地球科学引用本文复制引用
黄金莉,赵大鹏..P-wave tomography of crust and upper mantle under Southern California: Influence of topography of Moho discontinuity[J].地震学报（英文版）,2003,16(6):577-587,11.基金项目
Japan Society for Promotion of Science (11440134) and Chinese State Key Program of Basic Research on Mechanisms and Predictions of Strong Continental Earthquakes (G19980407) （11440134）
