强地震前后重力观测中异常变化现象的研究

分析了2001年昆仑山口西M_S8.1地震和2004年印尼M_S8.9地震前后部分重力观测的变化, 对这些采样间隔在1分钟以下的重力数据进行了高通滤波和频谱分析。 结果表明, 在昆仑山口西M_S8.1地震前, 乌鲁木齐和库尔勒观测台在二个时段分别同步出现了异常变化。 一次是在2001年11月3~5日, 另一次在2001年11月11~13日; 这二次异常都表现为颤动信号的出现, 而且后一次的强度要大于前一次; 颤动信号的周期主要集中在几十分钟。 印尼M_S8.9地震前, 这二个台也记录到类似的异常信息, 但颤动的幅度很小; 同时武汉观测台的超导重力仪也记录到了颤动信号, 该信号一直持续到地震的发生。 这些信息对于识别、 认识慢地震, 进而探索与强地震发生之间的关系具有重要意义。

Analysis of anomaly in gravity observation before and after strong earthquakes

In order to explore the anomaly variation before and after the great Kunlun Mountain MsS. 1 earthquake on November 14, 2001 and Sumatra Mw9. 0 earthquake on December 26, 2004, the minutely sampled data are analyzed, which covered before and after the earthquakes. Butterworth high pass filtered results and spectrograms show that there are anomaly changes at stations of Urumqi and Korla at two time spans before the Kunlun Mountain Ms8.1 earthquake, which appeared from November 3 to 5 and from November 11 to 13, respectively. Both anomalies are expressed as vibration signal with low frequency, and intensity of the latter is stronger. But no vibration like these appeared at the other stations. The same signals are recorded at stations of Korla and Urumqi before Sumatra Mwg. 0 earthquake. At the same time, the recording curve of superconducting gravimeter in Wuhan became thicken beginning from the afternoon of December 15, 2004.