三峡库区巴东地震(M_s5.1)成因机制及次声波信号  

Seismogenesis of Badong Earthquake(M_s5.1)in Three Gorges Reservoir Area and Infrasound Anomaly

作　　者：李献瑞 曾佐勋[2,3,4] 周强[5] 贺赤诚 刘江平[1] 赵娟[3,6] 潘黎黎[2,4] 

机构地区：[1]中国地质大学地球物理与空间信息学院,湖北武汉430074 [2]华中构造力学中心,湖北武汉430074 [3]中国地质大学教育部长江三峡库区地质灾害研究中心,湖北武汉430074 [4]中国地质大学地球科学学院,湖北武汉430074 [5]成都理工大学工程技术学院,四川乐山614000 [6]中国地质大学机械与电子信息学院,湖北武汉430074

出　　处：《地球科学（中国地质大学学报）》2014年第12期1793-1806,共14页Earth Science-Journal of China University of Geosciences

基　　金：国家"985"创新平台建设项目"地震及其次生地质灾害研究";国家自然科学基金重点项目(No.41230206)

摘　　要：2013年12月16日三峡库区巴东发生Ms5.1地震.根据eigen-6c2模型研究了巴东地区的8-638阶卫星重力异常，结果表明：该地区场源深度为10km的地壳为局部重力低异常，反映了该处物质密度较周围偏低，形成低密度层.同时，研究了该地区速度结构剖面，结果表明：巴东地区地壳5-9km及10-15km深处存在上下两个低速层，上部低速层与水库渗水有关，下部低速层与地幔热流体的上涌有关.低密度层和低速层的确定为韧性流变层的存在提供了证据.巴东地震是地壳深部能量的长期集聚与突发释放，属构造地震.然而，库水下渗引起的上部低速异常降低了断层活动的阈值，震前库水载荷的变化对此次巴东地震的发生起到了触发作用.通过对比次声波和地震波，我们得出次声波仪记录到的异常信号为本地次声波.On 1 6 December,2013,an earthquake of M s 5.1 occurred in the Badong County,the Three Gorges reservoir area, China.Using the EIGEN-6C2 model,the satellite 8-638 order gravity anomalies in this area were studied.The results show that there is a regional low gravity anomaly beneath Badong area at 10 km,which may imply that rock density this area of is lower than its surroundings.Meanwhile,the profiles of crustal velocity structure of this area indicate the existence of two low-velocity layers at depth of 5-9 km and 10-1 5 km respectively.We believe that the upper layer is closely related to the reservoir seep-age and the lower layer may result from the upwelling of the mantle hydrothermal fluid.The low-density layer and the two low-velocity layers provide an evidence for the existence of a possible ductile layer.The occurrence of Badong earthquake is due to the long-term energy accumulation and abrupt release at the deep crust,thus it is a tectonic earthquake.The low-velocity anom-aly in the upper crust caused by reservoir seepage decreased the threshold value of fault activities and the change of water load of this reservoir might trigger the Badong earthquake.By comparing the infrasound with seismic waves,we conclude that the infrasound anomalies recorded by the infrasound monitor array are local infrasound.

关 键 词：巴东地震 卫星重力异常 深部结构特征 水库触发地震 次声波异常 天然地震 

分 类 号：P315.2[天文地球—地震学]