Research on Seismicity and Source Parameters of Small Earthquakes in the Zipingpu Reservoir before the Wenchuan M_S 8. 0 Earthquake
Research on Seismicity and Source Parameters of Small Earthquakes in the Zipingpu Reservoir before the Wenchuan M_S 8.0 Earthquake作者机构:Earthquake Administration of Siehuan ProvinceChengdu 610041 China
出 版 物:《Earthquake Research in China》 (中国地震研究(英文版))
年 卷 期:2010年第24卷第3期
页 面:292-303页
学科分类:081504[工学-水利水电工程] 070801[理学-固体地球物理学] 07[理学] 08[工学] 0708[理学-地球物理学] 0815[工学-水利工程]
基 金:sponsored by the research project on reservoir earthquake monitoring and prediction technique (2008BAC38B03-02) China
主 题:Reservoir-induced earthquake activity Zipingpu reservoir Sourceparameters Apparent stress
摘 要:Based on the digital seismic waveform data observed from regional and reservoir seismic networks,the seismicity and source parameters in the Zipingpu reservoir area from January 1,2000 to May 11,2008 before the Wenchuan MS8.0 earthquake are studied. The analysis shows a continuous activity of small earthquakes before the Wenchuan MS8. 0 earthquake. The level of seismic activity was from ML2.0 to ML3.0 in recent years. The impoundment of Zipingpu reservoir started in September 2005 and the obvious increment of seismic activities occurred in February 2008,but according to the analysis of the longer time series,the frequency and intensity of seismic activities do not exceed its range,which means it is still a fluctuation of regional seismic activities or tectonic activity. At the same time,we also studied the spatio-temporal distribution and the change of apparent stress difference in the source region before the great earthquake,and the results show that the apparent stress values of small earthquakes are generally higher than fitted values of apparent stress in the reservoir area in the nearly three months before the Wenchuan MS8.0 earthquake. It can be seen from the spatial distribution of apparent stress difference,that the epicenter of the earthquake is located at a low stress distribution area,and the relatively high apparent stress difference is at the east of the epicenter. Apparent stress increment occurred in local areas.