芦山地震前后川滇地区地壳水平形变特征研究

为获取芦山地震前后川滇地区地壳的形变特征,利用陆态网2009—2013年和2014—2016年两期全球卫星导航系统(GNSS)水平速度场资料分别计算并对比分析了地震发生前后主应变率场、最大剪应变率场、面膨胀率场及基线长度的变化情况。结果显示芦山地震之前龙门山断裂带主要以压缩应变为主,面压缩应变和最大剪应变均处于高值区,震后能量部分释放,压缩形变程度减弱,但其西南方向的安宁河断裂带和鲜水河断裂带南段出现明显的压缩应变高值区,同时南汀河断裂带附近也呈现较明显的压缩应变。岷江断裂带附近区域的压缩应变虽然减弱,但仍然没有改变它的应变状态,这可能促使了2017年九寨沟Ms7.0地震的发生。

Reseach on the horizontal deformation characteristics of the Sichuan-Yunnan region before and after the Lushan earthquake

Aiming at the crustal deformation characteristics of the Sichuan-Yunnan region before and after Lushan earthquake,the principal strain rate field,maximum shear strain rate field,surface expansion rate field and baseline length changes before and after the earthquake were calculated using the global navigation satellite system(GNSS)horizontal velocity field data of the crustal movement observation network of China during 2009-2013 and 2014-2016.The results showed that the Longmenshan fault zone was dominated by compressive strain before the Lushan earthquake.The compressive strain and maximum shear strain were in high value area.The energy was released after the earthquake,and the compression deformation was weakened.But there were two significant high value zones of compressive strain in the Anninghe fault zone and south of Xianshuihe fault zone which were located in the southwest of Longmenshan fault zone.At the same time,there was also obvious compressive strain near the Nantinghe fault zone.The compressive strain in the vicinity of the Minjiang fault zone was weakened;however,the state did not change.It might promote the occurrence of the Jiuzhaigou Ms7.0 earthquake in 2017.