岫岩5.4级地震前后拐角频率比的变化特征

本文在利用多台研究1999年11月29日和2000年1月12日发生在辽宁岫岩Ms5.4级和5.1级地震前拐角频率比随时间变化的基础上,对岫岩、营口、苏家屯、丹东、宽甸、北镇、新民单台记录的纵横波拐角频率比fcp/fcs做了比较详细的波谱分析。结果表明:在震中距小于200 km以内的不同方向的台站,记录到的地震波拐角频率比值在5.4级前和后均出现不同程度的异常显示,能够捕捉到一些带有短临性质的信息,不过,距震中较远的台站,地震波拐角频率比值在震前异常不如近台明显,表明不同距离的台站,记录的地震拐角频率比值存在着差异。

Change characteristics of corner frequency before and after Xiuyan M5.4 Earthquake

According to the researches on the corner frequency proportion of Xiuyan Ms5.4 and Ms5.1 Earthquakes occurred respectively on 29 November 1999 and 12 January 2000 in Liaoning Province,we found that the corner frequency proportion changes of P-wave to S-wave with time are observed in following several seismic stations:Xiuyan,Yinkou,Shujiatuen,Dandong,Kuandian,Beizheng and Xingming.And then we made the detail spectrum analysis on the corner frequency proportion of fcp/fcs.Our study shows that the seismic stations that the epicenter distance is less than 200 km in all directions can recorde the abnormal changes of the corner frequency proportion of seismic P-wave to S-wave before and after Xiuyan M5.4 Earthquake.The corner frequency index of seismic waves can include the information of earthquake with the short-impendent character.But if the epicenter distance is greater than 200 km,the proportion changes of corner frequency are not clear before an earthquake.So we think that the clear proportion changes of corner frequency can be detective when the seismic stations are near an earthquake epicenter.