Dislocation model for current crustal deformation in and around Southern Taiwan, China

Using dislocation model of seismic deformation and the hybrid global inversion method, we analyze the 1990-1995 annually GPS data from 89 stations in southern Taiwan and its neighboring area and discuss the origin of the observed deformation field. Based on the geologic investigation and seismic observation we simply assume six blocks and nineteen fault patches in the studied area. The results show that the Philippine Sea plate moves, relative to the Eurasian plate, at a velocity (69 ± 2) mm/a in 317°. ± 2°. About a half of the rate is concentrated on the Longitudinal Valley fault (LVF), and the other half of the convergence spread over the boundaries among the west blocks. The Philippine Sea plate and the Central Range move toward northwestward. In the west of the Central Range zone, the motion of the blocks accords with the observed fan-shape distribution of the maximum principal stress. The faults between the Western Foothills and the Coastal Plain geological provinces have main thrust components, and the dips turn small from south to north. The fault widths are about 10km, implying that they are locked, and most of the large historical earthquakes occurred here.