2020年1月19日伽师M_(S)6.4地震前后的基岩温度变化  

CHANGE IN BEDROCK TEMPERATURE BEFORE AND AFTER JIASHI M_(S)6.4 EARTHQUAKE IN XINJIANG ON JANUARY 19,2020

作　　者：陈顺云[1] 宋春燕[2] 闫玮[2] 刘琼颖 刘培洵[1] 卓燕群[1] 张智河[3] CHEN Shun-yun;SONG Chun-yan;YAN Wei;LIU Qiong-ying;LIU Pei-xun;ZHUO Yan-qun;ZHANG Zhi-he(State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Xinjiang Pamir Intracontinental Subduction National Field Observation and Research Station Beijing 100029,China;Earthquake Agency of Xinjiang Uygur Autonomous Region,Urumqi 830011,China;School of Biomedical Engineering,Capital Medical University,Beijing 100069,China)

机构地区：[1]中国地震局地质研究所,地震动力学国家重点实验室,新疆帕米尔陆内俯冲国家野外科学观测研究站,北京100029 [2]新疆维吾尔自治区地震局,乌鲁木齐830011 [3]首都医科大学,生物医学工程学院,北京100069

出　　处：《地震地质》2021年第2期447-458,共12页Seismology and Geology

基　　金：中国地震局地质研究所基本科研业务专项(IGCEA2001,IGCEA1815);国家重点研发计划项目(2018YFC1503304,2019YFC1509202)共同资助。

摘　　要：2020年1月19日发生的伽师M_(S)6.4地震正好位于基岩温度观测区内,且西克尔观测台距离微观震中仅约1.3km,这为分析地震前后的地温变化提供了机会。结果显示:(1)在伽师M_(S)6.4震前及同震均观测到了清晰的地温变化。同震响应的出现,意味着震前的这些变化与地震有关,可能属于前兆信号。(2)时间上,伽师地震前的基岩温度先是在稳定背景上出现异常变化,变化达到峰值后回落,一段时间后才发生地震。临近地震时,基岩温度呈现明显的加速上升变化。这种临震前的加速特征可能与地震亚失稳或成核过程有关。(3)空间上,震前变化出现在发震断层或附近,而在距离发震断层较远的测点基本没有观测到明显的异常信息,预示着短临前兆更倾向于“近场”信息;从深度上看,只有局部深度的位置能观测到震前变化,前兆观测在深度上存在较明显的不确定性,理想的情况应该是开展多深度联合观测,避免漏掉关键的前兆信息。(4)结合2014年11月22日康定M_(S)6.3地震的观测记录进行了对比分析,结果表明:与伽师地震类似,康定M_(S)6.3地震前发震断层或附近基岩温度测点的观测结果也出现了明显变化,这意味着伽师地震前的温度变化并不是孤例。总之,从地震前后的基岩温度变化看,前兆信息具有近场、构造相关及对应力变化敏感的特征。Recent studies have confirmed that the bedrock temperature changes when the crustal stress changes,and the information of dynamic change in crustal stress can be obtained through the observation of bedrock temperature.Moreover,there are abundant fluids in the shallow crust,and the deformation of the crust will inevitably lead to the migration of fluids,which will change the bedrock temperature.The temperature change of bedrock is equivalent to the secondary fluid thermal effect caused by crustal stress change and may be an another indirect sensitive index of crustal stress dynamic change.The bedrock temperature data of Xianshuihe fault zones show that the variation of groundwater flow rate after the Kangding M_(S)6.4 earthquake is consistent with the zoning characteristics of co-seismic volumetric strain in the strike-slip earthquake,indicating that the variation of near-field fluid migration characteristics is probably related to the variation of co-seismic static stress change.Moreover,the response form of bedrock temperature to the dynamic change of crustal stress and its secondary fluid effect is not consistent,as the former shows step-rise charac-teristics,while the latter shows exponential variation.The observation of bedrock temperature itself can obtain the dynamic change information of crustal stress and the information of shallow crustal fluid migration.Compared with crustal stress change,the variation range of fluid secondary heat effect caused by stress change may be significantly magnified(approximately an order of magnitude),which is more conducive to capturing signals,and thus may even obtain precursory fluid change information.On January 19,2020,an M_(S)6.4 earthquake occurred in Jiashi,which happened in the bedrock temperature observation network.In particular,the Xike er observation station is about 1.3 kilometers away from the epicenter,providing an opportunity to analyze bedrock temperature changes before and after the earthquake.The results showed that:(1)Obvious changes in bedrock temperatur

关 键 词：基岩温度 伽师地震 康定地震 地震前兆 地震亚失稳 

分 类 号：P315.72[天文地球—地震学]