广西桂平西山井水位同震特征和机理初探

Primary Analysis on Characteristics and Mechanisms of Co-seismic Response of Water Level at the Xishan Well, Guiping City, Guangxi Zhuang Autonomous Region

摘要:

收集了2008～2016年广西桂平西山井水位观测数据及全球5级以上地震资料，分析井孔记录水震波的能力、水震波形态特征及影响因素，初步探讨了西山井同震的机理，获得以下认识：桂平西山井对全球M_S≥7地震具有较好的同震响应能力，水震波的形态主要为振荡型，少数呈现阶升型。井-含水层观测系统、地震震级、井震距是影响井孔记录水震波能力的主要因素。含水层介质受瑞利面波作用会发生体积变化，导致水位振荡，是形成振荡型水震波的可能机理。阶变型水震波的形成与区域应力场增强、介质变化及构造活动等因素有关。西山井水位阶升与周边中强地震活动存在较好对应关系，该认识可为地震预测研究提供参考。

Abstract:

Water level observation data at the Xishan well,Guiping City,Guangxi Zhuang Autonomous Region and global earthquakes with magnitude greater than or equal to 5.0 are collected from 2008 to 2016. The capability of recording co-seismic response,characteristics and its influence factors of water level oscillation are analyzed,the mechanism of co-seismic response is discussed and the following conclusions are reached. The well can record co-seismic response of most global earthquakes with magnitude greater than or equal to 7.0. The morphological of most water level change with seismic wave is oscillation,and the minority is step change. Well-aquifer observation system,magnitude and distance from well to earthquake epicenter are the main factors that affect the ability of well bores recording water level fluctuation. The possible mechanism of water level oscillation is the volume of aquifer media changed by seismic Rayleigh wave. Water level step change is related to the factors such as regional stress field enhancement,medium change and tectonic activity. There is a good correspondence between the water level rises of the Xishan well and moderate-strong seismic activities around it. This understanding is beneficial for earthquake prediction research.