摘要
2020年1月19日新疆伽师发生M_(S)6.4地震,震前约45小时震源区曾发生M_(S)5.4地震,构成典型的前-主-余型地震序列,显著且丰富的前震活动为研究主震成核过程提供了宝贵的基础数据.本文收集了M_(S)6.4地震震中100km范围内6个地震台站的波形数据,以重定位后的地震目录作为模板,利用匹配定位方法(Match&Locate)对M_(S)6.4地震前后(2019年12月1日至2020年1月31日)的小地震进行了检测和定位,检测得到4664个地震事件,其中261个事件发生在伽师M_(S)6.4地震之前,序列目录的完备震级从M_(L)1.6降低到M_(L)1.1.基于检测目录,利用修正的大森公式计算M_(S)5.4前震序列的p值偏低,表明前震序列衰减缓慢.根据地震活动时空分布,伽师M_(S)5.4地震前26天内和伽师M_(S)6.4地震前2天内,发震断层附近存在由地震活跃转为相对平静的过程.另外,伽师M_(S)6.4主震前2天内的地震活动存在向主震位置迁移、收缩的现象,可能标志着断层已进入亚失稳阶段.
On January 19,2020,the M_(S)6.4 earthquake occurred in Jiashi,Xinjiang.About 45 hours before the earthquake,the M_(S)5.4 earthquake occurred in the focal area,which formed a typical earthquake sequence with foreshocks.The significant and abundant foreshock activities provided valuable basic data for studying the nucleation process of the main earthquake.In this paper,the waveform data of 6 seismic stations within 100km of the Jashi M_(S)6.4 earthquake epicenter are collected.With the relocated earthquake catalog as the template,the small earthquakes before and after the Jashi M_(S)6.4 earthquake(from December 1,2019 to January 31,2020)are detected and located by the Match&Locate method.A total of 4664 earthquake events were detected,261 of which occurred before the Jiashi M_(S)6.4 earthquake.The complete magnitude of the sequence catalog was reduced from M_(L)1.6 to M_(L)1.1.According to the modified Omori formula,the p value of M_(S)5.4 foreshock sequence is low,which indicates that the attenuation of foreshock sequence is slow.According to the spatial and temporal distribution of the detected catalog,the earthquake activity becomes relative quiet in the vicinity of the seismogenic fault within 26 days before the Jiashi M_(S)5.4 earthquake and 2 days before the Jiashi M_(S)6.4 earthquake.In addition,the seismic activity in the two days before the Jiashi M_(S)6.4 earthquake migrated to the mainshock epicentre and contracted,which may indicate that the fault has entered the meta-instability stage.
作者
邓世广
蒋海昆
DENG ShiGuang;JIANG HaiKun(China Earthquake Networks Center,Beijing 100045,China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2022年第9期3322-3334,共13页
Chinese Journal of Geophysics
基金
国家重点研发计划(2018YFC150330502)资助。
关键词
伽师M_(S)6.4地震
前震活动
地震检测与定位
微震迁移
序列衰减
Jiashi M_(S)6.4 earthquake
Foreshock activity
Earthquake detection and location
Earthquake migration
Sequence decay
