2014年于田M_S7.3地震序列的频谱特征分析及其前震识别

Spectral characteristics of 2014 Yutian M_S7.3 earthquake sequence and its application in foreshock discrimination

利用新疆区域数字地震台网的波形资料,对2014年2月12日于田MS7.3地震前震和余震序列的频谱特征进行了分析。基于Brune模型,对观测记录进行仪器响应、传播路径和场地响应的校正,使用遗传算法对于田地震序列103次ML≥3.0地震的震源谱进行了反演计算。结果表明:1前震序列的拐角频率相对偏低,扣除地震矩影响后,余震的拐角频率有明显增高的趋势;2距离震中最近的YUT台资料分析显示,于田地震几次前震活动的台站观测谱相对较为独立,与主震以及彼此之间的相关系数均不高;3序列事件和主震的台站观测谱相关系数的变化反映了序列发展的动态破裂过程,相关系数较低的事件基本上偏离了主震破裂区而发生在分支断裂上;4前震的震源谱中存在异常的高频成份。

Based on waveform records from the Xinjiang Regional Seismic Network,the paper analyses the spectral characteristics of foreshocks and aftershocks of February 12,2014 Yutian Ms7. 3 earthquake sequence. We use genetic algorithm to invert source spectrum of 103 ML≥3. 0events of the sequence. The results show that：（ 1） corner frequency of foreshocks is relatively lower than that of aftershocks;（ 2） using the nearest station＇s（ YUT） data,we find that the observed spectrums of foreshocks are relatively independent of each other, the correlation coefficients of foreshocks and that of foreshocks to mainshock are on the low side;（ 3） the variation of correlation coefficients of observed spectrums implies dynamic rupture process of the earthquake sequence and most of the events with low correlation coefficients occurred on branch faults,which deviate from the main rupture area;（ 4） anomalously high frequencies of seismic radiation from foreshock sources are detected,which are probably due to an anomalous rigidity of the seismogenic medium. These features may be usable in foreshock discrimination.