摘要
通过分析汶川 M 8.0地震前后山西地震带 GPS 速度场以及由此计算得到的现今构造应变率场,结果显示：（1）汶川 M 8.0地震后,山西地震带各区域的运动方向均不同程度向西偏转,太原盆地及其以北的区域由1999-2007年的 SW 或 SSW 向转为 SWW 向,且运动速率由平均约2 mm/a增加到约4 mm/a,太原盆地以南的区域由之前的 SSE 向转为 SW 向。（2）汶川 M 8.0地震后,山西地震带的应变率场显著增强,大同盆地、太原盆地北段和临汾盆地西南段形成了三个压性应变集中区,2010年在这三个区域内分别发生了大同 M 4.5、阳曲 M 4.6和河津 M 4.8地震,可能由于这种压性应变积累的区域应力场环境有利于山西地震带中强地震的孕育和发生。（3）2009-11年,受日本 M 9.0地震的影响,山西地震带向西运动的速率有所减弱,应变率场张性变化明显,太原盆地及其以北区域平均速率下降为约2-3 mm/a,太原盆地以南的区域由 SW 向转为整体向南运动的格局,有恢复到1999-2007年背景运动状态的迹象。
We obtain the horizontal velocity field and tectonic strain rate field of the Shanxi seis-mic zone derived from Global Positioning System（GPS）data before and after the Wenchuan M 8. 0 earthquake.The results indicate that after the Wenchuan M 8.0 earthquake,the velocity of each region in the Shanxi seismic zone deflected westward in varying degrees.The north area including Taiyuan Basin shifted to SWW from SW and SSW directions in 1 999 -2007,and the velocity de-veloped from an average of approximately 2 mm/a to 4 mm/a.In addition,the area south of Taiyuan Basin shifted to SW from a SSE direction.The strain rate field in the Shanxi seismic zone was significantly enhanced after this earthquake and formed three compressive strain concentra-tion areas in Datong Basin,north Taiyuan Basin,and southwest Linfen Basin.In these respective areas,the Datong M 4.5,Yangqu M 4.6,and Hejin M 4.8 earthquakes occurred in 2010.These earthquakes may have occurred because a regional stress field environment with compressive strain accumulation is beneficial to the formation and occurrence of a moderate earthquake in the Shanxi seismic zone.Moreover,because of the Japan M 9.0 earthquake,the westward velocity of the Shanxi seismic zone was weakened,and the strain rate field expanded obviously during 2009 to 201 1.In addition,the velocity in the north area including Taiyuan Basin decreased to approximate-ly 2~3 mm/a,and the area south of Taiyuan Basin moved toward the south from the SW direc-tion.This area may return to the background velocity of that during 1 999 to 2007 in the future.
出处
《地震工程学报》
CSCD
北大核心
2014年第3期634-638,共5页
China Earthquake Engineering Journal
基金
地震科技星火计划(XH13004)
山西省青年科技研究基金(2011021024-1)
地震行业科研专项"中国综合地球物理场观测-鄂尔多斯地块周缘地区"(201208009-14)
山西省科技攻关计划项目(20090311084)
关键词
山西地震带
汶川M8.0地震
GPS速度场
应变率场
变化特征
Shanxi seismic zone
Wenchuan M 8.0 earthquake
GPS velocity field
strain rate field
variation characteristic
