以2008年汶川8.0级地震震中所在区域的9个固定台站的连续地震波形数据及震中区中国地震科学台阵记录的远震事件波形数据为研究对象,在对连续地震波形低频异常信号进行提取的同时,利用远震事件波形中的P波及其尾波数据探测震中区域部分台站地下结构信息,试图对主震发生前后出现的低频异常信号进行构造解释。研究结果显示:①9个固定台站提取出的地震波低频信号在2008年4月17日至2008年4月19日同步出现持续约40小时的先升后降异常形态,同时伴有间断性突跳并在震后密集呈现; ②震中附近研究测线在不同时段内岩石圈结构出现变形,且在震中附近,位于发震断裂上的台站与非发震断裂上的台站相比,其地下结构变化更明显。震中附近研究测线的岩石圈结构在不同时段变形现象是使用与提取低频异常信号相同频段(0～5Hz)的数据所得到的,反映地震连续波形中记录到的低频异常信号与震源区地下结构变形密切相关。

In this article,we analyze the continuous seismic waveform data from 9 fixed seismic stations in the region where the epicenter of the 2008 Wenchuan M8.0 earthquake occurred,combining with the remote event waveform data recorded by the China Seismological Array in the epicentral region. At the same time,the P-wave and its coda of the remote event waveform are used to detect the underground structure information of some stations in the epicentral region. we attempt to make a structural interpretation of some seismic stations in the epicentral region. The results show that:① The low-frequency signals of seismic waves extracted from 9 fixed seismic stations appeared the abnormal pattern of first rise and then fall,which lasted about 40 hours from April 17,2008 to April 19,2008,at the same time,it is accompanied by intermittent sudden jumps and present densely after the earthquake. ② The deformation of the lithospheric structure at different time intervals was observed from the survey line data near the earthquake epicenter,and the underground structure of the station located on the seismogenic fault changes more obviously than that on the non-seismogenic fault. The deformation phenomena of the lithosphere structure near the epicentral line are obtained by using the data of the same frequency band(0～5Hz)as that of the low frequency abnormal signal,which reflects that the low frequency abnormal signal recorded in the seismic continuous waveform is closely related to the deformation of the lithosphere in the focal area.

P315

国家自然科学基金(11962021)、中国地震局监测预报司预报处震情跟踪面上课题(20190201012019)共同资助