中国大陆东南边缘海现时地壳运动与地震动力学综合研究

在东亚大陆动力学和西太平洋动力学背景下 ,定量研究中国大陆东南边缘海的现今区域地壳运动、动力学及地震危险性。基于 1994～ 1998年福建 -台北网、中国大陆网、台湾 -吕宋 (菲律宾 )网和东亚大陆及西太平洋的 IGS网等 4种不同空间尺度的 GPS测量结果 ,结合近 10 0年来的强震震源机制解、近 2 0余年来跨断层形变网、精密水准网、激光测距网及原地应力测量等结果 ,以及地球物理数值模拟与地质学成果 ,通过对多层次构造运动的分析、多学科结果的互验互补和整体综合研究 ,获得如下结果 :( 1)本研究区同时存在陆、海相互对进的两种地壳水平运动 :大陆东南沿海 11～ 12 mm/ a向东南、海洋对大陆 3mm/ a向西北以及台湾东海岸 53mm/ a向西北的运动 ;( 2 )台湾岛可能存在着以 2 4°N附近为其旋转轴的右旋运动 ;( 3) GPS和地形变测量求出现今区域应力场主压应力方向为 NW( NWW)向 ,与不同时间尺度的地震学和地质学结果一致 ;( 4 )观测与数值模拟共同证实 ,印度板块和菲律宾海板块对欧亚板块的联合动力作用是导致本区上述地壳运动的原因 ;前者导致的地壳运动速度比后者约大 4倍 ,但前者仅导致准均匀场 ,而后者则可产生变形局部化过程的非均匀场 ,从而为强震孕育提供动力 ;( 5)菲律宾海板块在台湾东侧对欧亚板块

INTEGRATED RESEARCH ON CURRENT CRUSTAL MOVEMENT AND EARTHQUAKE DYNAMICS IN MARGINAL SEA，SOUTHEAST OF CHINA CONTINENT

In order to study quantitatively the current regional crustal movement and dynamics and the earthquake risk in southeast marginal sea of China continent under the background of southeast Asian dynamics and west pacific dynamics,on the basis of four different scale GPS survey results of the Fujian-Taibei net,China continent net,Taiwan-Luzon(Philippine) net and the IGS net in east Asian and west Pacific from 1994 to 1998,combining the results of the source mechanism of strong earthquake in recent hundred years,the crossing fault deformation net in recent two decades, the precise leveling net,the laser ranging net and the original stress surveying net and the numerical simulation of geophysics and geology achievement,through the analysis of the multi-layer tectonic movement,the verification of different science results with each other and the integrated research,we have obtained following results:1)There are two different crustal movements at the same time in studying region,one moving to sea from continent and the other moving to the continent from sea;the velocity of the marginal sea in southeast of continent moving to the southeast is 11-12 mm/a and to northwest is 3 mm/a,the velocity of the east coast of Taiwan moving to northwest is 53 mm/a.2)There may be a right lateral movement in Taiwan,its rotating axis is near the 24°N.3)The main compression stress direction of regional stress field from GPS and surface deformation survey is NW(NWW),which is consist with the results from the seismology and geology in different time scale.4)The survey and numerical simulation proved that the integrated force of the India block and the Philippine block to the Eurasia block lead to the crustal movement as described before,the velocity of the crustal movement come from the former is four times as large as that from the later,but the first only produced an uniform field,the later produced an inhomogeneous field which can generate deformation localization and provide the energy for the strong earthquake preparation.5)The comression and obduction to Eurasia block from Philippine block at the east of Taiwan is the most direct force sorce:from east Taiwan zone to west Taiwan zone,to outside zone of southeast coast zone,to inside zone of southeast coast zone,the crustal deformation and the activity of earthquake decrease by degrees synchronously.6)With the fault from Quanzhou bay to Yongan as the boundary,many current crustal movements in two sides take on remarkable regional diversity,which may have relation to the additional effect of the right lateral movement of Taiwan to continent.7)Although the most energy has been consumed at the east of Taiwan when the Philippine block moving to the west and Taiwan protects southeast coast,but with the slowly energy accumulation,this region still has the possibility of occurrence of M≥6 earthquake,particularly, we should pay attention to the sea-board of Quanzhou-Shantou.