用单纯形法和PTD法对2016年新疆阿克陶M_S6.7地震序列的震源深度测定分析
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摘要
用单纯形法计算了阿克陶M_S6.7主震的震源深度,结果为7.5 km,但单纯形法对设定的初始深度依赖值过高,震源深度值不一定可靠。用PTD法计算了阿克陶M_S6.7主震的震源深度,结果为9.4 km,且用了44个台站的震相数据共组成99个有效样本数参与了计算,不仅样本数多,而且震源深度样本数的集中度也比较符合高斯分布的特征,所以震源深度值可信度高,也非常接近国内和国外地震研究机构给出的此次地震的震源深度。当主震的震源深度已知且适合单纯形法设定的初值时,用单纯形法来计算地震序列的震源深度,不仅残差小,而且软件实现简单,确保了地震序列的按时提交。再用PTD法来检验该地震序列震源深度的准确性,结果显示,2种方法得到的震源深度差值不超过10 km,符合中国地震台网对震源深度误差的要求。
The focal depth of the Aktao M_S6.7 main shock is calculated by simplex method. The result is 7.5 km. However, the dependence of the simplex method on the initial depth is too high, and the focal depth is not necessarily reliable. The focal depth of the Aktao M_S6.7 main shock is calculated by PTD method. The result is 9.4 km. A total of 99 effective samples from 44 stations are used to calculate the focal depth. Not only are there many samples, but also the concentration of the focal depth samples is in accordance with the characteristics of Gauss distribution. Therefore, the reliability of the focal depth values is high and non-reliable. It is close to the focal depth of the earthquake given by domestic and foreign earthquake research institutions. When the focal depth of the main shock is known and suitable for the initial value set by the simplex method, the simplex method is used to calculate the focal depth of the seismic sequence, which not only has a small residual, but also has a simple software implementation and ensures the timely submission of the seismic sequence. Then PTD method is used to test the accuracy of the focal depth of the seismic sequence. The results show that the difference between the two methods is not more than 10 km, which meets the requirements of the Chinese seismic network for the error of the focal depth.
The focal depth of the Aktao M_S6.7 main shock is calculated by simplex method. The result is 7.5 km. However, the dependence of the simplex method on the initial depth is too high, and the focal depth is not necessarily reliable. The focal depth of the Aktao M_S6.7 main shock is calculated by PTD method. The result is 9.4 km. A total of 99 effective samples from 44 stations are used to calculate the focal depth. Not only are there many samples, but also the concentration of the focal depth samples is in accordance with the characteristics of Gauss distribution. Therefore, the reliability of the focal depth values is high and non-reliable. It is close to the focal depth of the earthquake given by domestic and foreign earthquake research institutions. When the focal depth of the main shock is known and suitable for the initial value set by the simplex method, the simplex method is used to calculate the focal depth of the seismic sequence, which not only has a small residual, but also has a simple software implementation and ensures the timely submission of the seismic sequence. Then PTD method is used to test the accuracy of the focal depth of the seismic sequence. The results show that the difference between the two methods is not more than 10 km, which meets the requirements of the Chinese seismic network for the error of the focal depth.
引文
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[16] 宋秀青,缭发军,刘双庆,等.2014年新疆于田MS7.3地震序列的震源深度测定[J].中国地震,2014,30(2):198-207.
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[3] Glennon M A,Chen W P.Rupture of deep-focus earthquakes in the north-western Pacific and their implications on seismogenesis[J].Geophy J Inter,1995,120(3):706-720.
[4] 张国民,汪素云,李丽,等.中国大陆地震震源深度及其构造含义[J].科学通报,2002,47(9):663-668.
[5] 黄耘,李清河,张元生,等.江苏及邻区地震重新定位和构造特征分析[J].地球物理学报,2008,51(1):175-185.
[6] Saikia C K,Woods B B,Thio H K.Calibration of the Regional Crustal Waveguide and the Retrieval of Source Parameters Using Waveform Modeling[J]Pure and Applied Geophysics,2001,158(7):1 301-1 338.
[7] 倪四道.大陆地震震源深度测定方法研究进展[C]//中国地球物理学会第二十八届年会论文集.北京:中国地球物理,2012:11.
[8] 曲延军,王琼,聂晓红.新疆南部构造区带与地震活动状态研究[J].内陆地震,2010,24(4):298-306.
[9] 李艳永,热依木江,唐明帅,等.利用震相方位角改善地震台网稀疏地区地震定位精度[J].地震地磁与研究,2016,37(2):57-62.
[10] 刘文学,刘贵忠,周刚.新疆和周边地区地壳厚度和VP/VS比值变化的接收函数约束[J].地球物理学报,2011,54(8):2 034-2 041.
[11] 新疆地震局分析预报室.“3400公里走时表”及其应用、新疆走时表工作的设想[J].地震地磁与研究,1982,3(4):25-30.
[12] 陈向军,上官文明,宋秀青,等.新疆全区和分区地壳速度模型的分析[J].中国地震,2014,30(2):178-187.
[13] 陈贵美,杨选,刘锦.广东数字地震台网‘十五’系统的几种地震定位方法的定位效果分析[J].华南地震,2009,29(1):69-78.
[14] 朱元清,夏从俊,李平.确定震源深度的PTD方法及其应用[J].地震地磁观测与研究,1997,18(3):21-29.
[15] 王新岭,张国民,马宏生,等.用PTD方法测定巴林左旗5.9级地震震源深度[J].地震,2004,24(4):51-56.
[16] 宋秀青,缭发军,刘双庆,等.2014年新疆于田MS7.3地震序列的震源深度测定[J].中国地震,2014,30(2):198-207.