应用迭代叠加法分离震源谱的理论探讨

Theoretical Investigation on Earthquake Source Spectra Isolation by Iteratively Stacking Separation

推导了通过迭代叠加法计算震源谱的解析表达式。结果表明,分离出的震源谱与台站项无关,但是包含与事件-台站位置分布非均匀性有关的路径项影响,这种影响将关系到拟合震源谱求取应力降的正确性。通过基于实例的数值计算,进一步证实了这一理论推断。最后,对如何正确地应用迭代叠加法计算应力降进行了讨论,给出可行的正确获取地震应力降的研究方案,为更准确地利用地震台网资料获取震源信息提供了基础。

The correctness of the earthquake source spectra derived from array data with an iteratively stacking method is checked by analyzing the expressions of iterative stacking in each step. The expression of the finally derived source spectra term shows that it has nothing of the station term, but will be affected by the path term dependent on the source-receiver configuration, which is further confirmed by numerical simulations with iteratively stacking method. Considering stress drop might be wrongly estimated when stations or events are unevenly distributed, the paper provides a strategy to derive the correct stress drop in typical conditions of station- event configurations. It will be helpful to correctly acquire seismic source information from seismic data.