Determination and interpretation of earthquake source locations in Sichuan Province, China

Abstract

This thesis involves locating and interpreting earthquakes from the Sichuan Province, China. The main contributions of this research are: successfully fitting the travel time data of three explosions to a two-layer crust model; and the improvement in locating earthquakes. To achieve these objectives, the Gauss-Newton method is applied iteratively to find the nonlinear least squares solution. The Monte Carlo method and the Gauss- Newton method were jointly used to locate events and simultaneously optimize the crust model. The iterative station correction method is adopted to compensate the incorrectness of the velocity model and to improve the event locations. The joint master event method can improve the location of the events near the master event. The modified Hypoinverse not only can locate events based on the spherical crust model, but can also jointly improve the crust model used. A three-dimensional crust model is next to be optimized and to improve event locations further. We also present geological interpretation about earthquake locations in Sichuan and their tectonic implications.