云南地区震源机制及应力场特征

发布时间：2018-09-07 07:26

【摘要】：利用云南和四川区域台网记录的地震波形资料,采用CAP方法计算得到了云南地区1999年1月至2014年8月268次M_L≥4.0地震的震源机制解,结合收集的哈佛大学1976年以来109次地震的震源机制解,分析了云南地区震源机制解分类及其区域特征。基于上述震源机制解资料,采用区域应力张量阻尼反演方法计算了云南地区每个网格的最佳拟合构造应力张量,并利用最大主应力计算方法计算得到了云南地区最大水平主应力的方向。结果表明:1)研究区地震震源类型以走滑型为主,其次为正断型,逆断型相对较少,震源机制空间分布特征明显,反映了研究区不同区域受力源及其作用方式的差异性;2)云南地区应力场方向呈现一定的空间连续性,最大水平主压应力方向由北向南呈顺时针旋转,由西向东呈逆时针旋转,同时应力场方向表现出空间的不均匀性,EW和SN方向分别存在2个应力转换区。应力场反演结果显示,云南地区应力场较为复杂,主应力方向变化很大,不同区域存在明显差异。
[Abstract]:Based on the seismic waveform data recorded by Yunnan and Sichuan regional network, the focal mechanism solutions of 168 earthquakes with M_L (>4.0) in Yunnan area from January 1999 to August 2014 are obtained by CAP method. Combined with the focal mechanism solutions of 109 earthquakes collected from Harvard University since 1976, the classification and regional characteristics of focal mechanism solutions in Yunnan area are analyzed. Based on the above focal mechanism solution data, the best fitting tectonic stress tensor for each grid in Yunnan area is calculated by using the regional stress tensor damping inversion method, and the direction of the maximum horizontal principal stress in Yunnan area is calculated by using the maximum principal stress calculation method. Secondly, the positive fault type, the reverse fault type is relatively few, and the spatial distribution characteristics of focal mechanism are obvious, which reflects the differences of stress sources and their action modes in different regions of the study area; 2) The stress field direction in Yunnan region shows a certain spatial continuity, and the maximum horizontal principal compressive stress direction rotates clockwise from north to south, and counterclockwise from west to east. At the same time, the direction of stress field shows spatial inhomogeneity. There are two stress transformation zones in EW and SN directions, respectively.
【作者单位】：江苏省地震局;云南省地震局;
【基金】：江苏省科技支撑-社会发展项目(BE2016804,BE2011814) 中国地震局地震科技星火计划项目(XH15020Y);中国地震局震情跟踪青年课题项目(2016010121) 江苏省地震局青年基金重点项目(201402)共同资助
【分类号】：P315.33

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