摘要
分析了1997年荣昌5.2级地震的震源机制,主压应力方位为NW向,震源力学作用机制呈走滑兼有较强的倾滑分量。根据成都遥测地震台网记录的波形资料,研究了荣昌震区1994～1998年36次小震机制解,统计的优势压应力方位也是NW向。同时给出了小震震源参数随时间的变化过程,其动态起伏过程稳定。在四川盆地及南缘地区,发生走滑兼有较强的倾滑分量的地震破裂的比例相对较大。这往往与震区的地腹断裂有关,也与分层滑脱的力学机制相一致。利用近场测震台测量的快S波偏振显示震区近地表浅层介质的各向异性特征。
In this paper the focal mechanism for M5.2 earthquake occurred in Rongchang, Chongqing Municipality on August 13, 1997, is analyzed. The direction of the pr incipal compressional stress is in NW. And faulting plane is characterized by ob vious normal dip slip component. Focal mechanisms for 36 small events located in Rongchang region are determined by using waveform data in 1994～1998 from Chen g du telemetering Seismic Network. The dominant direction of compressional stress is also in NW. Changes of source parameters for the small earthquakes with time demonstrate stable dynamic process with small fluctuations. There is relatively larger percentage of earthquake faulting with obvious dip slip component in Sich uan Basin and on its southern fringe. That is usually related to buried faults i n epicentral areas, and also consistent with layered detachment mechanism as wel l. The polarization of fast S waves measured on recordings from near stations sh ows anisotropy in shallow medium near the free surface.
出处
《地震》
CSCD
北大核心
2003年第3期79-88,共10页
Earthquake
基金
国家重点基础研究发展规划项目(95130505)。
