中国台湾南部及其周边岛屿现今地壳形变的位错模型

通过建立非震形变的位错模型,用混合全局反演方法,拟合了中国台湾南部1990-1995年间的GPS观测资料.根据地质构造和地震观测,构筑了包括6个刚性块体和19个断层的简单模型.反演结果表明,菲律宾海板块以(69±2)mm/a,方向为317°±2°的速度与欧亚板块会聚,其中约一半的会聚率在台东纵谷消耗掉,另外部分则平均分配在其西边的块体交界处.菲律宾海板块和中央山脉地质区均向西北方向挤压,过了中央山脉后,块体运动呈扇形分布,与应力方向一致.西部麓山地质区与滨海平原地质区交界处的断层均以逆冲分量为主,由南向北倾角逐渐变小,断层宽度一般为10km左右,均表现为强锁定,历史上的大地震多发生在这个地区.

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 strongly locked, and most of the large historical earthquakes occurred here.