印尼9.0级地震前后远场水平地壳微动态变形

FAR FIELD HORIZONTAL MICRO-DYNAMIC CRUSTAL DEFORMATIONS BEFORE AND AFTER INDONESIA Mw9.0 EARTHQUAKE

利用中国大陆GPS基准站及震中附近IGS站数据,研究了2004年12月26日印尼苏门答腊9.0级地震前后GPS观测到的远场水平位移微动态变形过程。震前E分量位移序列出现"分群"现象,震中东北侧大陆板块上的GPS站点表现出受挤压向东的运动,而位于断裂带西北侧大陆板块上的站点则表现出受引张向西运动的趋势,具有大尺度空间的协调一致性,与理论孕震模型符合较好。远至3 000km的站点也观测到了地震的同震位移,同震位移矢量有整体向震中汇聚的特点,反映了震时俯冲板块和上覆板块会聚作用对远场的影响。而震后由于地震断层的强烈运动,使得一些点位位移态势发生了较震前异常更明显、持久的改变。

Using the data of GPS fiducial stations in China and IGS stations around the epicenter,we studied the horizontal micro-dynamic crustal deformations before and after Indonesia Mw9.0 earthquake in far field.The E component showed regional distinction changes before the earthquake.It was that the stations located in north-east from the epicenter moved east,controlled by pinching action,whereas,stations located in northwest from the epicenter moved west ward,effected by stretching force.It showed a characteristic of harmony and consistency in a large-scale space,corresponding better with the theoretical seismogenic patterns.Small but significant co-seismic jumps are clearly detected by the stations which are more than 3 000 km far from the epicenter.The co-seismic deformation vectors almost pointed towards the earthquake epicenter on the whole,reflecting the flocking impact of the diving slab towards overlaying plate on a far-field.And some of these sites change their dislocations obviously acted by the strong movement of earthquake fault after the earthquake.