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暴雨触发局部地震活动的一个典型例子:2010年6月广西凌云—凤山交界3级震群活动
引用本文:蒋海昆,杨马陵,孙学军,吕坚,阎春恒,吴琼,宋金,赵勇,黄国华,张华,姚宏,牟剑英,李金,曲均浩.暴雨触发局部地震活动的一个典型例子:2010年6月广西凌云—凤山交界3级震群活动[J].地球物理学报,2011,54(10):2606-2619.
作者姓名:蒋海昆  杨马陵  孙学军  吕坚  阎春恒  吴琼  宋金  赵勇  黄国华  张华  姚宏  牟剑英  李金  曲均浩
作者单位:1. 中国地震台网中心,北京 100045; 2. 广东省地震局,广州 510070; 3. 广西壮族自治区地震局,南宁 530022; 4. 江西省地震局,南昌 330039; 5. 中国地震局地震预测研究所,北京 100036; 6. 中国地震局地质研究所,北京 100029
基金项目:国家"十一五"科技支撑计划项目,地震行业科研专项项目
摘    要:在前期严重干旱的背景下,2010年6月27~30日广西西北部出现大暴雨过程,大范围积水成涝.降雨量最大的凌云、凤山交界于6月28日17时开始出现密集的微震活动,形成显著的震群事件.自6月28日至7月15日共记录地震2739次,其中2~2.9级(ML,下同)41次,3级以上地震3次,最大为7月1日10时27分3.2级地震...

关 键 词:震群  暴雨  震源深度  流体触发  孔压变化
收稿时间:2010-08-10

A typical example of locally triggered seismicity in the boundary area of Lingyun and Fengshan following the large rainfall event of June 2010
JIANG Hai-Kun,YANG Ma-Ling,SUN Xue-Jun,L Jian,YAN Chun-Heng,WU Qiong,SONG Jin,ZHAO Yong,HUANG Guo-Hua,ZHANG Hua,YAO Hong,MU Jian-Ying,LI Jin,QU Jun-Hao.A typical example of locally triggered seismicity in the boundary area of Lingyun and Fengshan following the large rainfall event of June 2010[J].Chinese Journal of Geophysics,2011,54(10):2606-2619.
Authors:JIANG Hai-Kun  YANG Ma-Ling  SUN Xue-Jun  L Jian  YAN Chun-Heng  WU Qiong  SONG Jin  ZHAO Yong  HUANG Guo-Hua  ZHANG Hua  YAO Hong  MU Jian-Ying  LI Jin  QU Jun-Hao
Institution:1. China Earthquake Networks Center, Beijing 100045, China; 2. Earthquake Administration of Guangdong Province, Guangzhou 510070, China; 3. Earthquake Administration of Guangxi Zhuang Autonomous Region, Nanning 530022, China; 4. Earthquake Administration of Jiangxi Province, Nanchang 330039, China; 5. Institute of Earthquake Science, China Earthquake Administration, Beijing 100036, China; 6. Institute of Geology, China Earthquake Administration, Beijing 100029, China
Abstract:An intensive rainfall occurred from June 27 to June 30 2010 in the northwest part of Guangxi province, large areas became waterlogged. Before that, a serious drought situation continued for several months in this region. Following the large rainfall, an earthquake swarm with thousands events occurred in the boundary area of Lingyun and Fengshan, where maximum precipitation appeared. There are 2739 earthquakes being recorded since June 28 to 15 July, among them, 41 events with magnitude from ML2.0 to ML2.9 and 3 events with ML≥3.0 (the maximum event is ML3.2) occurred on 1 July. There is an obvious spatio-temporal correlation between swarm and large rainfall, the highest seismicity is a little behind the maximum precipitation of the rainfall in time. Shallow karst structure consisting of carbonatite rock materials are prolific in a large area around the epicenter, the epicenter is located at the crossing area of NW faults and NE faults. The fault fracture zone is the preferential channels for fluid intrusion. Earthquakes concentrate in a cluster and the focal depths are shallow. The size of earthquake distribution (radius) and focal depths are smaller than 1.6 km for 63% earthquakes, 2.5 km for 88% earthquakes and 3.4 km for 98% earthquakes. The seismic phase analysis on relatively large earthquakes shows that the fluid has been involved in the swarm and it also shows some features of karst collapse. Due to the quick migration of fluid along the fault surface, it seems that the small earthquakes are distributed along the fault, but the focal mechanism solution of relatively large earthquakes does not support the guess that the swarm is resulted from the fault movement, in another words, there is no relationship between the swarm activity and the tectonic movement. The U-D first motions of most earthquakes, recorded by the field seismic sensor in the epicenter area, are downward and the ratio of down direction is larger for smaller earthquakes, this means that most of small earthquakes may be produced by karst collapse or crack closure. The results of quantitative detection based on ETAS model show that the fluid triggering action is very strong on the swarm activity. Meanwhile, the earthquake self-generation is also very strong. According to the 1-D diffusion equation, the temporal variation of pore pressure in different depths, caused by the fluid intrusion, has been simulated, it pointed out that the increment of pore pressure caused by the fluid intrusion is the major mechanical reason of the swarm. The seismogenic mechanism of the Lingyun-Fengshan swarm has been proposed in the final.
Keywords:Swarm  Rainfall  Focal depth  Fluid triggering  Variation of pore pressure
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