于田地区强震前加卸载响应比异常及强震复发间隔  

Load-unload response ratio anomalies before the Yutian strong earthquakes and its earthquake recurrence interval estimation

作　　者：刘月[1] 田勤俭 张永仙[1] 王辉[1] 尹祥础[1,3] LIU Yue;TIAN QinJian;ZHANG YongXian;WANG Hui;YIN XiangChu(Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China;China Earthquake Disaster Prevention Center,China Earthquake Administration,Beijing 100029,China;Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China)

机构地区：[1]中国地震局地震预测研究所,北京100036 [2]中国地震灾害防御中心,北京100029 [3]中国科学院力学研究所,北京100190

出　　处：《地球物理学报》2023年第2期616-625,共10页Chinese Journal of Geophysics

基　　金：国家重点研发计划(2018YFE0109700);国家自然科学基金(U2039207和41704093);国家重点研发计划(2022YFC3003500);中国地震局地震预测研究所基本科研业务费专项(2019CSES0105)资助。

摘　　要：21世纪以来,于田地区发生了4次MS≥6.0地震,包括两次MS7.3地震,引起广泛关注.我们基于加卸载响应比方法 (Load-Unload Response Ratio, LURR),以地震目录(来自中国地震台网中心)为资料,对2008-2020年于田地区4次强震进行分析.结果显示,4次地震前,均在震源区及附近检测到LURR异常,且震前LURR异常空间分布随时间的变化过程类似.强震发生滞后于LURR异常峰值:2008年MS7.3、2014年MS7.3及2020年MS6.4地震,滞后于LURR异常峰值1~2 a;2012年MS6.2地震发生于LURR异常峰值后半年.相邻的民丰地区,1924年发生了MS7.3和MS7.2地震,于田-民丰地区强震较为活跃.我们基于地震导致的地壳介质损伤的平板模型,探索于田及周边地区的强震复发特征.得到于田-民丰地区长期的损伤-愈合速率为3.86×10^(-4)/a.基于单次M 7.5地震造成的损伤,估算这一区域7.5级左右地震的复发间隔约50 a.本文对于田地区强震前介质特征的变化,及区域强震复发间隔提出新的认识.Four MS≥6.0 earthquakes struck Yutian area in Xinjiang in the 21st century, including two strong earthquakes with magnitude of MS7.3, arising great concern. Based on the Load-Unload Response Ratio(LURR) method, we studied the LURR abnormal characteristics before the four MS≥6.0 earthquakes in Yutian by using the earthquake catalog provided by China earthquake Network Center. The results showed that LURR anomalies with similar features of changes were detected before the four earthquakes. Peak value of LURR anomalies were observed prior to the earthquake occurrences: the 2008 MS7.3, 2014 MS7.3 and 2020 MS6.4 earthquakes occurred 1~2 years following the LURR anomaly peaks;the 2012 MS6.2 event was half a year after the LURR anomaly peak. In 1924, two earthquakes with magnitude of MS7.3 and MS7.2 occurred in Minfeng adjacent to Yutian, indicating that seismicity in Yutian-Minfeng region was active. By introducing the plate model which could estimate the damage of crust media caused by earthquakes, we explored the recurrences of strong earthquakes in Yutian and its surrounding areas. The cumulative damage for Yutian and surroundings was deduced, with a rate of 3.86×10^(-4)/a. An earthquake with magnitude of about 7.5 had a recurrence interval of about 50 years, estimated from the damage caused by one single MS7.5 event. This study provided us some scientific accumulation for the understanding of the characteristics of the medium around the seismogenic zone and the earthquake occurrence for Yutian region.

关 键 词：于田地震 加卸载响应比 阿尔金断裂带 平板模型 损伤演化 

分 类 号：P315[天文地球—地震学]