青海地区地震序列参数的早期特征研究

Statistical Features of Earthquake Sequence Parameters of the Qinghai Area

摘要:

采用时间序列的"传染型余震序列"（ETAS）模型系统估算了青海地区地震序列参数，并对地震序列的震后早期特征进行分析。采用"自然边界法"选取了2009年以来青海地区9个地震序列，利用"震级-序号"法确定了每个地震序列的完整性震级M_c，并对每个地震序列进行估算。研究表明，截止震级选取对地震序列参数的影响很大，在应用中需谨慎。α值和p值的稳定时间与序列的主震震级间没有明显的关系，主震震级较大的地震序列，序列参数的稳定时间可能较短；主震震级较小的地震序列，序列参数的稳定时间也可能较长。同一个地震序列，α值和p值的稳定时间与不同截止震级间也没有明显的对应关系。最后给出了研究区域地震序列参数的最长稳定时间和最短稳定时间。

Abstract:

To investigate the characteristics of an earthquake sequence of the Qinghai area,we fitted the aftershock sequence of the 9 earthquake sequences since 2009 in this region with the Epidemic-Type Aftershock Sequence(ETAS)model. The integrity magnitudes of nine earthquake sequences were estimated with the magnitude-rank and with the adopted different cutoff magnitude M_c. It is observed that we have to be cautious because the cutoff magnitude M_c has a certain effect on the value of α,k and p. There is no obvious relation between the stability time of the alpha value and the p value in the Qinghai area and the magnitude of the mainshock earthquake. The stability time of the sequence parameters may be shorter for the earthquake sequences with a larger mainshock magnitude. The earthquake sequences with small magnitudes of mainshocks may also have longer stability times. In the same earthquake sequence,there is no obvious correspondence between the stability time of alpha and P values and different cut-off magnitudes. Finally,the longest stable time and the shortest stability time of the parameters are given.