广西靖西地区2次强降雨触发的震群活动

Two Earthquake Swarms Triggered by Heavy Rainfall Events in Jingxi,Guangxi

2010年7—8月和2011年6—7月,在连降暴雨的背景下,广西靖西地区发生了2次显著有感震群,均造成一定社会影响,并呈现诸多有别于典型构造地震的活动特征。分析了2次震群的活动过程、波形和震源参数特征,并综合岩溶水文地质、地球物理和力学等多学科的资料和方法,探讨了2次显著震群的性质和成因机制。结果显示,2次震群均与强降雨过程密切关联,地震主要发生在岩溶分布区,且主要集中在地下暗河岩溶管道系统的上方,震源深度极浅。2次震群的地震波形记录和震源参数与典型构造地震的参数存在较大差别。综合现场调查资料分析认为,2次震群可能是流体触发的浅表岩溶塌陷活动所至。

Under the background of continuous rainstorms,two significant sensible earthquake swarms occurred in Jingxi of Guangxi Zhuang Autonomous Region in July and August 2010 and June and July 2011,both of the earthquake swarms had caused certain social impaction and showed many characteristics different from those of typical tectonic earthquakes.The activity process,waveform and source parameter characteristics of two seismic swarms are analyzed,and the nature and genetic mechanism of the two seismic swarms are also discussed by combining the data and analytical methods of karst hydrogeology,geophysics and mechanics.The results are shown as follows:the two swarms are closely related to the process of heavy rainfall,the earthquakes mainly occur in the karst distribution area,and are mainly concentrated above the underground river karst pipeline system,with very shallow focal depth;The waveform records and source parameters of the two swarms is different from tectonic earthquakes.Based on the analysis of field survey data,it is concluded that two earthquake swarms may be caused by the fluid-triggered collapse of shallow karst.