基于汶川地震同震地下水位变化反演含水层体应变  

Estimating aquifer volumetric strain caused by the 2008 Wenchuan earthquake from tidal effect of groundwater

作　　者：史浙明[1] 王广才[1] 刘春国[2] 

机构地区：[1]中国地质大学(北京)水资源与环境学院,中国北京100083 [2]中国地震台网中心,中国北京100045

出　　处：《地震学报》2012年第2期215-223,282,共9页Acta Seismologica Sinica

基　　金：国家自然科学基金重点项目(40930637);地震行业科研专项(200808079);教育部高校博士点学科基金(20100022110001)资助

摘　　要：许多地下流体监测井在地震发生时都能记录到同震水位变化,而利用地下水位的同震响应特征以及水位固体潮效应可以反演地震对含水层产生的体应变量.本文尝试从大尺度上对大地震引起的体应变变化进行研究,为此收集了位于我国大陆不同构造活动区5口地下流体监测井两年半的水位数据资料进行分析,去除干扰项,提取出水位固体潮成分,进行调和分析求取潮汐因子,并反演出汶川MS8.0地震对这5口井所在含水层产生的体应变量.结果显示,汶川大地震对这5口井-含水层造成的体应变量基本在10-7量级.地震引起的体应变随距离的衰减规律比较复杂,其不仅与震中距有关,而且与活动断裂带的展布和地壳岩体结构等密切相关.Water level in many wells will change in response to an earthquake. One can use the coseismic water level change and its response to tide effect to calculate the volumetric strain in aquifer induced by the earthquake. We tried to study the changes in volumetric strain induced by great earthquakes in large scale. The two and a half years of original groundwater level data, recorded in the five wells located in different tectonic settings, were firstly corrected by removing both the trend and barometric pressure effect. Then harmonic analysis was used to calculate the tidal factor for each well-aquifer system, and furtherthe volumetric strains of these five well-aquifer systems were calculated based on the tidal factors and groundwater level changes in response to the Wenchuan earthquake. The result shows that the volumetric strain in aquifers caused by the earthquake may reach 10^-7. The attenuation of volumetric strain induced by the earthquake is complicated, and it may be determined by the distribution of active faults, structure of crustal media, as well as the earthquake epicentral distance.

关 键 词：地下水水位 潮汐因子 体应变 汶川地震 

分 类 号：P315.723[天文地球—地震学]