Determination of mean stress field in eastern Dabieregion from focal mechanism solution analysis
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摘要: 利用地震的震源机制解资料，得到应力张量在地理坐标系下的表达式，进而可计算平均应力张量. 通过求平均应力张量的本征向量，即可得到其主轴方向，并由此推断区域应力场方向．利用东大别地区219次地震的震源机制解资料，比较了不同相似程度和不同起算震级资料得到的主轴方向，认为该方法计算结果非常稳定，主轴方位角的误差小于5deg;，倾角的误差小于10deg;．计算结果表明，东大别地区最大主压应力轴sigma;1的方位角为267deg;，倾角为5deg;；最小主压应力轴sigma;3的方位角为358deg;，倾角为4deg;.表明该地区受东西向的水平挤压和南北向的水平拉张作用．
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关键词:
- 应力张量 震源机制解 应力场 东大别地区
Abstract: By using focal mechanism solutions, we present the expression of stress tensor in geographic coordinates. And then calculate average stress tensor and its eigenvectors to get the direction of principal axis,which can be extrapolate the direction of regional stress field. According to the focal mechanism solutions of 219 earthquakes in East Dabie, the analysis result of directions of principal axis in different similarity and magnitudes are given. This method is simple and the result is stable, the error of azimuth of principal is less than 5 deg; and the plunge is less than 10deg;. The result shows that the azimuth of principal axis sigma;1 is 267deg;, the plunge is 5deg;; the azimuth of principal axis sigma;3 is 358deg;, the plunge is 4deg;. It can be indicated that the East Dabie is forced by horizontal compression in EW and horizontal extension in NS. -
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