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震源机制解的可靠性越来越受到人们的重视 ,已有的检验工作证实中国早期或者手工作图测定的震源机制解可靠性极差。经比较 ,由远震波形反演的矩张量解 ,同一地震不同作者的结果之间差异甚小 ,可靠性较高 ;而基于P波初动方向测定震源机制解的格点尝试法所给出的解空间比其他方法要好。对 2 0 0 3年 4月发生在首都圈数字化地震台网范围内的 2次 4级地震进行了分析。取用不同的资料 ,由格点尝试法和 -P ,-S垂直向振幅比方法分别测定了震源机制解 ,二者基本一致 ,并且和过去当地发生的 5级以上地震的哈佛大学CMT解接近。这既说明了地震活动的继承性 ,也证实了震源机制解并非随机分布。由于中小地震发生的随机性 ,用统计的方法对用振幅比资料测定的震源机制解进行分析 ,结果是客观、恰当的
The reliability of focal mechanism solution has drawn more and more attention. The existing tests confirm that the focal mechanism solution of early or manual mapping in China is very poorly reliable. By comparison, the moment tensor solution derived from the teleseismic waveform has little difference between the results of different authors of the same earthquake and has higher reliability. However, the grid point method based on the initial motion direction of P wave The solution space is better than other methods. Two earthquakes occurred in April 2003 in the area of digital seismic network in the metropolitan area were analyzed. Taking different data, the focal mechanism solution was determined by lattice point-try method and -P, -S vertical amplitude ratio method, respectively, which are basically the same, and they are close to the Harvard CMT solution of earthquakes of magnitude 5 above that occurred in the past . This not only demonstrates the succession of seismicity, but also confirms that focal mechanism solutions are not randomly distributed. Due to the randomness of small and medium earthquakes, a statistical method is used to analyze the focal mechanism solution measured by the amplitude ratio data. The result is objective and appropriate