2023年2次肃北5级及以上地震的PI和LURR特征回溯性研究  

Retrospective study of PI and LURR characteristics of the two Subei earthquakes(M≥5.0)in 2023

作　　者：于磊[1] 曹均锋[1] 王建广 李伸亮 李鹏飞 王季雨 疏鹏 李玲利[1] 方良好 YU Lei;CAO Junfeng;WANG Jianguang;LI Shenliang;LI Pengfei;WANG Jiyu;SHU Peng;LI Lingli;FANG Lianghao(Anhui Earthquake Agency,Anhui Province 230031,China;Anhui Wuhu Earthquake Agency,Anhui Province 241000,China)

机构地区：[1]安徽省地震局,合肥230031 [2]安徽省芜湖市地震局,安徽241000

出　　处：《地震地磁观测与研究》2024年第3期31-38,共8页Seismological and Geomagnetic Observation and Research

基　　金：地震科技星火计划青年项目(项目编号:XH23021YB);中国地震局监测、预报、科研三结合课题(项目编号:3JH-202402004);安徽省重点研究与开发计划(项目编号:2022m07020005);郯庐断裂带肥东—庐江段发震规律及影响研究项目。

摘　　要：2023年10月24日和12月1日在甘肃省肃北县分别发生M_(S)5.5和M_(S)5.0地震,震中位于祁连山地震带西段,采用图像信息(PI)和加卸载响应比(LURR)探查2次地震孕育过程中应力状态和震后地震活动趋势,为分析祁连山地震带地震活动趋势提供参考。结果显示:①PI热点计算结果显示,肃北地区存在显著的背景应力异常,其幅度指示该区域在未来1年存在发生6级左右地震的可能;②LURR的时空演化特征进一步显示,2023年3月起LURR时序曲线呈显著上升异常变化,且异常空间分布持续向震源区迁移,表明在中短期内有发生强震的可能;③2次地震发生后,震源区LURR异常的时空特征仍呈现持续发展状态,尚未恢复到小于1的正常水平。因此,仍需关注祁连山地震带西段发生6级左右地震的可能。M_(S)5.5 and M_(S)5.0 earthquakes occurred in Subei County,Gansu Province on October 24 and December 1,2023 respectively which were located in the western section of the Qilian Mountain seismic belt.Pattern informatics(PI)and load/unload response ratio(LURR)are used to detect the stress state during interseismic and post-earthquake activity of the two earthquakeswhich provides reference for analyzing the future seismic activities of Qilian Mountain area.The results show that,①The PI hot spot calculation results indicate that there is a significant background stress anomaly in Subei area,and its amplitude indicates that there is a possibility of a magnitude 6 earthquake in this area in the next year.②The temporal and spatial evolution characteristics of LURR indicate that the stress state in the source region has significantly changed in 2023,the LURR time series curve has shown obvious abnormal upward changes since the beginning of 2023,and the spatial distribution of anomalies continues to migrate to the source region,which indicate the possibility of strong earthquakes in the short and medium term.③The temporal and spatial characteristics of LURR anomalies in the seismic area still show a continuous development state after the occurrence of the two earthquakes,and have not returned to normal levels.Therefore,it is still necessary to pay attention to the possibility of a magnitude 6 earthquake in the western part of the Qilian Mountain seismic belt in 2024.

关 键 词：肃北M_(S)5.5地震 肃北M_(S)5.0地震 图像信息法 加卸载响应比 祁连山地震带 

分 类 号：P315[天文地球—地震学]