2021年5月22日青海玛多M7.4地震前共和水温异常分析研究  

Anomalies of water temperature at Gonghe seismic station before the Maduo M7.4 earthquake on May 22,2021

作　　者：刘磊 张朋涛[1,2] 苏维刚 李霞[1,2] 赵玉红 冯丽丽[1,2] LIU Lei;ZHANG Pengtao;SU Weigang;LI Xia;ZHAO Yuhong;FENG Lili(Geodynamics Field Observation and Research Station of the Qinghai-Tibet Plateau, Xining 810001, Qinghai, China;Qinghai Earthquake Agency, Xining 810001, Qinghai, China)

机构地区：[1]青海格尔木青藏高原内部地球动力学野外科学观测研究站,青海西宁810001 [2]青海省地震局,青海西宁810001

出　　处：《地震工程学报》2021年第4期860-867,共8页China Earthquake Engineering Journal

基　　金：青海格尔木青藏高原内部地球动力学野外科学观测研究站专项;中国地震局地震科技星火计划项目(XH20063Y);2021年度震情跟踪定向工作任务(2021010308);青海省地震局地震科学基金课题(2021C02)。

摘　　要：2021年5月22日青海省玛多县发生M7.4地震,震前共和水温观测资料出现显著异常变化,震中距280 km,两套仪器水温异常形态表现为2021年2月28日—3月3日出现同步上升-下降转折变化,幅度分别为0.047~0.075℃、0.007~0.240℃,截止3月21日,两套观测曲线同步转平,与以往震例类似,异常结束62天后,发生玛多地震。通过不同时段的水化组分对比分析,讨论其差异性,认为:(1)水化学类型为HCO_(3)-Na、HCO_(3)·SO_(4)-Na,水-岩反应程度较弱;(2)Na-K-Mg三角图显示,水样点分布在异常出现后,部分平衡水区域与正常时段及震后水样的分布域差异性大。结果表明,异常出现后由于区域应力调整,导致地层中深部热水在向地表上升的过程中流经岩石地层时受到中等矿化的部分平衡水混入,使水体矿化度及水化组分发生显著变化,带入更多深部元素补给,结合异常形态及历史震例研究分析,认为该异常是较为可信的地震前兆异常。On May 22,2021,an M7.4 earthquake occurred in Maduo County,Qinghai Province.Before the earthquake,the water temperature recorded by two sets of observation equipment at Gonghe seismic station showed synchronous rise-decline change from February 28 to March 3,2021,and the observed values ranged from 0.047℃to 0.075℃and 0.007℃to 0.24℃,respectively.On March 21,the anomaly ended,and 62 days later,the Maduo earthquake occurred.Through a contrastive analysis of hydrochemical components during different periods,the conclusions are as follows:(1)The hydrochemical types were HCO_(3)-Na and HCO_(3)·SO_(4)-Na,and the degree of water-rock reaction was weak.(2)The chemical ions(Na^(+),Mg^(2+),Ca^(2+),SO^(2-)_(4) and HCO^(-)_(3))had obvious response to the fluctuation after the anomaly appeared.(3)The Na-K-Mg triangle diagram showed that the water samples were distributed in the area of partial equilibrium water after the anomaly appeared,which was greatly different from the immature water area during the normal period.The results showed that due to the regional stress adjustment after the anomaly appeared,the middle and deep hot water was mixed with the partial equilibrium water of medium salinity when it flowed through the rock stratum to the surface,resulting in significant changes in the salinity and hydrochemical components of water.Based on the analysis of the anomaly characteristics and historical earthquake cases,it is considered that this anomaly is a reliable earthquake precursor anomaly.

关 键 词：玛多7.4级地震 共和水温 异常特征 水化组分 

分 类 号：P315[天文地球—地震学]