利用加卸载响应比探查强震成核过程——以2020年新疆伽师6.4级地震为例  

Study on the nucleation process of strong earthquakes using the load/unload response ratio method—Taking the 2020 MS6.4 Jiashi,Xinjiang earthquake as an example

作　　者：贾东辉 余怀忠[4] 陈界宏 晏锐[4] 刘杰[4] 赵彬彬[2] 李泽平 马玉川[4] 苑争一 杨文[4] 李桂荣 李越帅[2] JIA DongHui;YU HuaiZhong;CHEN ChiehHung;YAN Rui;LIU Jie;ZHAO BinBin;LI ZePing;MA YuChuan;YUAN ZhengYi;YANG Wen;LI GuiRong;LI YueShuai(Xinjiang Pamir Intracontinental Subduction National Field Observation and Research Station,Urumqi 830011,China;Earthquake Agency of Xinjiang Uygur Autonomous Region,Urumqi 830011,China;Chengdu University of Technology,Chengdu 610059,China;China Earthquake Networks Center,Beijing 100045,China)

机构地区：[1]新疆帕米尔陆内俯冲国家野外科学观测研究站,乌鲁木齐830011 [2]新疆维吾尔自治区地震局,乌鲁木齐830011 [3]成都理工大学,成都610059 [4]中国地震台网中心,北京100045

出　　处：《地球物理学报》2024年第6期2232-2247,共16页Chinese Journal of Geophysics

基　　金：国家自然科学基金地震联合基金(U2039205);国家重点研发计划(2018YFE0109700);国家自然科学基金(42274014);国家重点研发计划(2023YFE0102902,2022YFC3003703);新疆维吾尔自治区重点研发专项(2022B03001,2020B03006)资助。

摘　　要：加卸载响应比(LURR)是基于非均匀脆性介质损伤演化提出的一种中短期地震预测方法,以往的研究中多以地震活动为响应量计算LURR,地球物理观测资料应用较少.本文基于地下流体、地壳形变、电磁、岩石地温等观测资料,运用加卸载响应比(LURR)方法研究2020年新疆伽师6.4级地震的孕育过程.震中300 km范围内的20个观测台站中,11个台站数据计算得到的LURR时间序列呈现明显规律性特征.震前数月-数天都出现相对异常高值,并在回落后发生地震,演化过程与使用震中200 km范围内小震活动计算的LURR时间序列一致.不同观测资料所得LURR异常阈值分别为:地下水位1.02、岩石地温1.0002、倾斜仪1.005、水温1.02、氢气1.02、地电阻率1.01、地磁1.02、小震活动1.5.从异常台站的空间分布上看,存在向震中迁移的过程,即随着主震发生时间的临近,检测到异常的台站位置与震中之间的距离越小,且在震中附近呈现加速过程.LURR异常的时空演化可能与岩石介质的亚失稳有关,反映了大震前震源区介质的成核弱化和加速破裂过程.上述演化过程可以通过原始观测曲线中记录的异常数量、空间分布及其随时间的演化加以证实.The Load-Unload Response Ratio(LURR)theory is a medium-to-short-term earthquake prediction method that relies on the damage evolution of heterogeneous brittle media.In previous studies,seismic activity was commonly used as the response for calculating LURR,and the utilization of geophysical observation data was relatively limited.This paper examines observation data such as underground fluid,crustal deformation,electromagnetic,and bedrock temperature,and focuses on the nucleation instability evolution of the 2020 Jiashi MS6.4 earthquake in Xinjiang,using the Load/unload response ratio(LURR)method within the observation stations located within a 300 km radius centered at the epicenter,the LURR time series derived from 11 stations show anomalously high peak values months to days before the mainshock,followed by a decrease after the earthquake.The anomalous thresholds for different geophysical field observational data are as follows:groundwater level 1.02,bedrock temperature 1.0002,inclinometer 1.005,water temperature 1.02 and hydrogen 1.02,geoelectric field 1.01,electromagnetic 1.02,seismic activity 1.5.The LURR anomalies exhibit a clear spatial regularity migrating towards the epicenter gradually.As the time approaches of the mainshock,the distance between the stations detecting anomalies and the epicenter decreases.Simultaneously,there is notable acceleration of migration near the epicenter.The spatio-temporal evolution of LURR anomalies may be closely related to the sub instability of the rock medium,reflecting the nucleation weakening and accelerated rupture process of the source media before a large earthquake.The calculated results are consistent with the number,spatial distribution,and evolution of geophysical anomalies identified in the raw observation data before the earthquake.

关 键 词：地球物理观测 加卸载响应比 亚失稳 成核弱化 地震前异常 

分 类 号：P315[天文地球—地震学]