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Title:: Research of Source Parameter and Stress State of Mabian-Daguan Tectonic Zone

Author(s):: RUAN Xiang; CHENG Wan-zheng; QIAO Hui-zhen; ZHANG Zhi-wei; FU Ying; (Earthquake Administration of Sichuan Province,Chengdu 610041,Sichuan,China)

Keywords:: focal mechanism; apparent stress; stress distribution; Mabian-Daguan tectonic zone

摘要:: 利用2000～2009年马边—大关构造带上的115次3级以上中小地震波形资料,计算了地震震源机制解和视应力等震源参数。根据震源机制解分析,马边—大关构造带平均主应力方向为NWW—SEE,错动类型显示,走滑型和倾滑型的地震所占比例相当。地震活动丛集的3个区段荥经—峨边、马边—盐津、鲁甸—巧家的平均主应力方向分别为NWW—SEE、NW—SE、NWW—SEE,呈现局部构造应力场方向特征。马边—大关构造带视应力分布不均匀,高值出现在云南大关—盐津一带地下20 km区域,而利店断裂及以北的地区视应力值相对较低。分析认为马边—大关构造带南段未来存在潜在的强震危险性。

Abstract:: Source parameters such as focal mechanism solutions and stress were calculated by using the waveform data of 115 M_L≥3.0 moderate small earthquakes in Mabian-Daguan tectonic zone from 2000 to 2009.According to focal mechanism solutions the direction of mean principle stress of Mabian-Daguan tectonic belt is NWW-SEE and the proportion of strike-slip earthquake is almost equal to dip-slip.The mean principle stress of three earthquake cluster regions namely Yingjing-Ebian,Mabian-Yanjin and Ludian-Qiaojia is NWW-SEE,NW-SE and NWW-SEE respectively,which reveal the characteristic of direction of local tectonic stress field.As the estimation of underground stress level apparent stress in Mabian-Daguan tectonic distributed unevenly.High values appear in the underground 20 km area of Daguan-Yanjin region of Yunnan Province,while in the Lidian fault and its north area apparent stress is relatively low.We thought there is potential earthquake risk in future in the south segment of Mabian-Daguan tectonic zone.