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有3种有用的区域深度震相sPg、sPmP和sPn以及与之相应的参考震相Pg、PmP和Pn。每种深度震相和它的参考震相间的到时差可以用来估计震源深度。我们开发了一种利用区域深度震相模拟(RDPM)的方法来估计中小地震的震源深度。对所有地震我们使用同一个震源机制来产生到时差。通过比较发现,用区域深度震相模拟方法得到的震源深度与用其他方法得到的震源深度是一致的。由于区域深度震相模拟方法得到的深度依赖于地壳模型,我们审查了这种依赖性并发现10%的地壳模型误差可引起大约10%～15%的深度误差。深度的绝对误差依赖于地壳模型的误差和震源深度本身。震中位置误差对所得的深度影响很小。通过分析理论的和观测的地震图发现,sPmP和PmP震相在某一距离窗中发育较好。在此震中距窗中,它们也较容易识别。我们证实了对sPmP和PmP的假定是正确的,以及区域深度震相在某些地区是不发育的,或不能分辨的。我们也展示了可用于识别区域深度震相的一些特征。
There are three useful regional depth phases sPg, sPmP and sPn and the corresponding reference phases Pg, PmP and Pn. The time difference between each depth phase and its reference phase can be used to estimate the focal depth. We have developed a method to estimate focal depths for small and medium earthquakes using the method of regional deep phase facies modeling (RDPM). For all earthquakes we use the same source mechanism to generate the time difference. By comparison, it is found that the focal depth obtained by the deep seismic facies simulation is consistent with the focal depth obtained by other methods. Since the depth obtained by the regional deep phase facies simulation method is dependent on the crustal model, we examined this dependence and found that a 10% crustal model error can cause a depth error of about 10% to 15%. The absolute error of depth depends on the crustal model error and focal depth itself. The epicenter position error has little effect on the resulting depth. By analyzing the theoretical and observed seismograms, it is found that the sPmP and PmP phases develop well in a certain distance window. In the epicenter distance window, they are also easier to identify. We confirm that the assumptions for sPmP and PmP are correct, and that the regional deep phase is undeveloped or indistinguishable in some areas. We also show some of the features that can be used to identify the deep phase of a region.