天山地震带空间集中度ΔC值演化特征  

The spatio-temporal evolution characteristics of seismic concentrative degreeΔC value in Tianshan earthquake belt

作　　者：马亚伟 孟令媛[1] MA Yawei;MENG Lingyuan(China Earthquake Networks Centre,Beijing 100045,China)

机构地区：[1]中国地震台网中心,中国北京100045

出　　处：《地震地磁观测与研究》2021年第3期15-24,共10页Seismological and Geomagnetic Observation and Research

基　　金：国家重点研发计划课题(项目编号:2017YFC1500502);中国地震台网中心青年科技基金(项目编号:QNJJ201905)。

摘　　要：采用新疆地区1990年以来的浅源地震目录,利用扩散链法去除余震,在小震空间集中度C值的研究基础上,进一步发展了C值变化量,即ΔC值的时空扫描计算方法,针对2000年以来天山地震带11次6级以上地震前ΔC值的演化过程,进行回顾性研究。结果表明,2012年新源—和静交界M_(S)6.6地震、2017年精河M_(S)6.6地震和2020年伽师M_(S)6.4地震之前,均出现较为明显的区域ΔC值异常,且3次地震前ΔC值异常演化时间均小于6个月,属于震中附近区域震前中短期异常变化。Based on the Xinjiang earthquake catalog since 1990,we studied the spatio-temporal variation of seismic concentrative degree C and developed a method of calculating the variation of C value,i.e.,ΔC value.The earthquake catalog was declustered by the diffusion chain method.Then we calculated the magnitude of completeness Mc.The result shows that the Mc for Tianshan earthquake zone varies from ML 1.0 to ML 3.0 since 2000 and keeps around ML 3.0 from 1990 to 2000.Therefore,our study is based on the events with magnitude larger than ML 3.0 in the catalog.Our method calculates C values in a step of one month and puts the results in a database.The current C value is subtracted from the average C value of the previous 10 years and then divided by the standard deviation to calculate the currentΔC value.Based on retrospective studies of 11 M_(S)≥6.0 earthquakes that occurred in the Tianshan seismic belt since 2000,we found that there wereΔC value anomalies around the epicentral areas before the Xinyuan-Hejing M_(S)6.6 earthquake in 2012,the Jinghe M_(S)6.6 earthquake in 2017,and the Jiashi M_(S)6.4 earthquake in 2020.The three earthquakes occurred in the vicinity of the highΔC area according to the spatio-temporal scanning results.The anomaly-time curves show that the evolution time of theΔC anomaly is less than half a year,indicating that theΔC value anomaly is a short to medium-term anomaly that appeared before an earthquake.

关 键 词：ΔC值 新源—和静M_(S)6.6地震 精河M_(S)6.6地震 伽师M_(S)6.4地震 

分 类 号：P315.7[天文地球—地震学]