Dislocation parameters of Gonghe earthquake jointly inferred by using genetic algorithms and least squares method

摘要

The Second Crustal Deformation Monitoring Center, China Seismological Bureau, has detected a marked upliftassociated with the Gonghe Ms=7.0 earthquake on April 26, 1990, Qinghai Province. From the observed verticaldeformations and using a rectangular uniform slip model in a homogenous elastic half space, we first employ genetic algorithms (GA) to infer the approximate global optimal solution, and further use least squares method to getmore accurate global optimal solution by taking the approximate solution of GA as the initial .parameters of leastsquares. The inversion results show that the causative fault of Gonghe Ms=7.0 earthquake is a right-lateral reversefault with strike NW60, dip SW and dip angle 37, the coseismic fracture length, width and slip are 37 km , 6 kmand 2.7 m respectively. Combination of GA and lean squares algorithms is an effective joint inversion method,which could not only escape from local optimum of least squares, but also solve the slow convergence problem ofGA after reaching adjacency of global optimal solution.