| Changes in source parameters of foreshocks and aftershocks of the 2001 M_S=6.0 Yajiang, Sichuan, earthquake |
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| 作者姓名： | 程万正 陈天长 魏娅玲 朱航 |
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| 作者单位： | Seismological Bureau of Sichuan Province，Chengdu 610041，China，Seismological Bureau of Sichuan Province，Chengdu 610041，China，Seismological Bureau of Sichuan Province，Chengdu 610041，China，Seismological Bureau of Sichuan Province，Chengdu 610041，China |
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| 基金项目： | State Key Basic Development and Programming Project Mechanism and Prediction of Continental Strong Earthquakes (95130505). |
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| 摘 要： | Introduction An MS=6.0 earthquake occurred on February 23, 2001 in Yajiang county, Sichuan Province. The earthquake is located on the east of the southeast segment of the Litang-Dewu fault with strike of NW. Before the event, on February 14, an MS=5.0 earthquake took place nearly in the same place. In 1948 an MS=7.3 earthquake occurred on the northwestern segment of the Litang fault. The length of the surface rupture belt caused by the earthquake is 70 km, which extended from Litang to…
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Changes in source parameters of foreshocks and aftershocks of the 2001 MS=6.0 Yajiang, Sichuan, earthquake |
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| CHENG Wan-zheng CHEN Tian-chang WEI Ya-ling ZHU HangSeismological Bureau of Sichuan Province,Chengdu ,China.Changes in source parameters of foreshocks and aftershocks of the 2001 M_S=6.0 Yajiang, Sichuan, earthquake[J].Acta Seismologica Sinica(English Edition),2003,16(4). |
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| Authors: | CHENG Wan-zheng CHEN Tian-chang WEI Ya-ling ZHU HangSeismological Bureau of Sichuan Province Chengdu China |
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| Institution: | Seismological Bureau of Sichuan Province, Chengdu 610041, China |
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| Abstract: | In this paper changes in focal mechanisms, parameters of wave spectra, and stress drops for the MS=5.0 foreshock and MS=6.0 mainshock in February 2001 in Yajiang County, Sichuan, and seismicity in epicentral region are studied. Comparison of focal mechanisms for the Yajiang earthquakes with distribution patterns of aftershocks, the nodal plane I, striking in the direction of NEN, of the Yajiang M=5.0 event is chosen as the faulting plane; the nodal plane II, striking in the direction of WNW, of the M=6.0 event as the faulting plane. The strikes of the two faulting planes are nearly perpendicular to each other. The level of stress drops in the epicentral region before the occurrence of the M=6.0 earthquake increases, which is consistent with increase of seismicity in the epicentral region. The rate decay of the Yajiang earthquake sequence, changes in wave spectra for foreshocks and aftershocks, and focal mechanisms are complex. |
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| Keywords: | Yajiang earthquake sequence characteristics source parameters |
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