2020年1月19日新疆伽师MS6.4地震前地震活动特征分析

简要介绍2020年伽师M S6.4地震周围地质构造背景,研究分析了M S6.4地震前新疆地区和柯坪块体地震活动状态、区域地震活动图像特征。结果表明:①本次地震前1~2年和震前半年,新疆境内中强和中小地震呈现“平静—成组活跃”或显著增强特征;②本次地震发生在柯坪块体M S≥6.0地震平静近15年的背景下,震前区域地震活动存在时间渐进的中短期异常特征,即震前2年,5级以上地震活动呈现NE向有序条带分布;震前1年南天山西段小震群累积月频度呈现“加速”活动特征;震前半年震区附近4级地震条带形成共扼分布特征;震前3个月震区附近出现地震窗超限异常;震前2个月震区附近地区视应力呈现显著高值异常;③震前地震活动具有较好的“长、中、短”期异常配套出现的特征。

ANALYSIS OF SEISMIC ACTIVITY BEFORE JIASHI M S6.4 EARTHQUAKE IN XINJIANG ON JANUARY 19TH,2020

Briefly introduced the background of geological structure around Jiashi M S6.4 earthquake in 2020,and analyzed the seismic activity status and regional seismic activity characteristics in Xinjiang region and Keping block before Jiashi M S6.4 earthquake.The results showed that:(1)1~2 years and half a year before M S6.4 Jiashi earthquake,moderate earthquakes and small earthquakes showed"calm-group active"state or significantly enhanced activity state;(2)M S6.4 earthquake of Jiashi occurred in the background that Keping block M S≥6.0 earthquake had calmed nearly 15 years,there were short and medium term abnormal characteristics of seismic activity before earthquake:2 years ago,M S≥5.0 seismic activity showed the“orderly strip distribution by NE direction”;1 year ago,the small earthquake swarms in the west section of South Tianshan mountain were active,the cumulative monthly frequency showed the characteristics of“accelerated”activity;half a year before the earthquake,there appeared abnormal seismic map of a conjugate distribution of M S≥4.0 earthquake dense belt;3 months ago,seismic area occurred earthquake window monthly frequency continuous over-limit anomaly;2 months ago,apparent stress showed high-value anomalies around seismic area;(3)seismic activities before the earthquake had the characteristics of“long,medium and short”abnormal matching.