利用2015—2018年川滇地区的流动重力观测资料,分析了2018年四川兴文5.7级地震和2019年珙县5.3级地震前不同时间尺度的重力场演变过程。结果 表明川滇地区的重力场变化对这2次地震有较好的反映:① 一年尺度的重力场变化图像较好地反映2次地震前重力场由“趋势性重力异常变化→低值变化→在重力变化高梯度带的零等值线附近发震”的演化过程; ②不同时间尺度重力场均显示,2次地震均发生在重力变化梯度带零等值线附近,进一步佐证了重力场动态变化图像对强震地点预测具有重要的指示意义。
Using the relative gravity measurement data in Sichuan-Yunnan region from 2015 to 2018,we analyzed the evolution process of gravity field in different time scales before Sichuan Xinxing MS5.7 in 2018 and Gongxian MS5.3 earthquakes in 2019. The results show that the variation of gravity field in Sichuan-Yunnan region closely linked with these two earthquakes. ① The annual scale of gravity field change image better reflect the evolution process of gravity field before two earthquakes,i.e. “trend gravity anomaly change→low value change→earthquake occur near the zero contour of gravity change high gradient zone”; ② The gravity fields in different time scales show that,these two earthquakes occurred near the zero contour of the gravity gradient,which further proves that the dynamic image of gravity field has important indication significance for the prediction of strong earthquake locations.
