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

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。

DETERMINATION AND ANALYSIS OF SOURCE DEPTH OF 2016 AKTAO M_S6.7 EARTHQUAKE SEQUENCE IN XINJIANG WITH SIMPLEX METHOD AND PTD METHOD

The focal depth of the Aktao MS6.7 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 MS6.7 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.