甘东南重力、b值异常与岷县-漳县M6.6地震关系探讨

Relationship Between the Gravity and b-value Anomalies in Southeast Gansu and the Minxian—Zhangxian M6.6 Earthquake

摘要:

利用甘东南测网2010—2014年的流动重力观测数据，分析2013年7月22日甘肃岷县—漳县M6.6地震前后1 a尺度的重力场变化，并结合地震b值图像和GNSS结果进一步分析甘东南重力、b值异常与岷县—漳县M6.6地震的关系，结果表明：（1）测区重力异常经历了由"区域重力负值变化→持续负值变化→转折上升正变化—发震→震后恢复变化"的时空演化过程；（2）岷县—漳县M6.6地震前后b值曲线出现"低值—高值—回落发震"的变化特征；（3）岷县—漳县M6.6地震发生在重力变化高梯度带上、"0"等值线附近和低b值区域。

Abstract:

In this paper, the gravity changes of one year scale before and after the Minxian—Zhangxian M6.6 earthquake on July 22, 2013 are analyzed using the mobile gravity observation data from 2010 to 2014 in southeast Gansu network, and then the relationship between the gravity and b-value anomalies in southeast Gansu and the Minxian—Zhangxian M6.6 earthquake is discussed considering the b-value image and global navigation satellite systems result. The results indicate the following: (1) The gravity anomaly in the study area underwent a spatiotemporal evolution from regional negative gravity change to constant negative change, positive change of turn and increase, earthquake occurrence, and then recovery after the earthquake; (2) before and after the Minxian—Zhangxian M6.6 earthquake, the b-value curve shows characteristics of low value-high value-reduction and shock; (3) the Minxian—Zhangxian M6.6 earthquake occurred in a high gradient zone of gravity change near the "0" contour line and the low b-value region.