2017年精河MS6.6地震前重力变化特征分析

Analysis of gravity changes before the Jinghe MS6.6 earthquake of 2017

摘要:

利用新疆地区北疆测网2015～2017年观测的共4期流动重力资料，分析研究区半年、1年尺度重力变化特征，并采用小波分解方法，对2017年8月9日精河M_S6.6地震前重力变化异常进行分解，分离了不同深度的重力异常。结果表明，震中附近的精河地区从2015年开始一直处于重力负值变化，同时，震中周围的重力正值变化集中区逐步向震中地区迁移，地震发生前震中以南60km处出现重力变化零值线，并且零值线两侧的重力累积变化量达到70μGal。小波分解后，4阶细节图较好地反映了精河地震前的重力异常，其与地震孕育发生有较好的对应性。

Abstract:

We used the four periods of the fluid gravity observation data from the northern Xinjiang networks from 2015 to 2017 to analyse the half year and the one year gravity change characteristics of the researched region, decomposed the gravitational anomalies before the August 9, 2017 Jinghe M_S6.6 earthquake with the wavelet decomposition method and extracted the gravitational anomalies in different depths. The result shows that there have been negative gravitational changes near Jinghe since 2015. Meanwhile, the positive gravity changes with high value around the epicenter have gradually moved to the epicenter region. There were gravity zero change line 60km south to the epicenter before the earthquake, and the gravity changes accumulated up to 70 microgal before the earthquake. After the wavelet decomposition, 4 order wavelet obviously reflects the gravitational anomalies of the Jinghe earthquake, and shows consistency with earthquake preparation. Different depths of gravitational anomalies could be extracted and the near surface or shallow gravity anomalies irrelevant to earthquake preparation could be removed using wavelet analysis.