汶川M_s 8.0大震前特征地脉动与台风差异分析

Difference Analysis of Characteristic Ground Pulsation and Typhoon before the Wenchuan M_s 8.0 Large Earthquake

文章利用我国15个宽频带数字台网记录的连续波形资料,分析了汶川8级特大地震震前地脉动波形。对比震前1~2天的周期变化,发现了几种低频特征地脉动波形,分别为:特征地脉动(I) (3~6秒)、特征地脉动(II) (20~30秒)、特征地脉动(III) (30~50秒)。特征脉动波与其它天然小震、远震波形及台风引起的脉动波(7~10秒)相比,均有明显差异。针对特征脉动波进行了周期、波长及振幅的量取,计算分析后表明这些特征脉动波之间能量差别很大,其中特征地脉动(I)、(II)和(III)最大振幅分别为正常脉动波的10−2、10−9和10−23倍。将四川及周边主要台站震前2小时,相隔10分钟记录的特征脉动波在地图上标出后,表现为在震中附近随时空连续变化的波动异常现象,并于大地震发生前一分钟沿发震断层出现明显分界线。特征脉动波时空动态分析可能提供重要的震前信息。

This paper uses the continuous waveform data recorded by 15 broadband digital networks in China to analyze the ground pulsation waveform before the Ms = 8.0 large Wenchuan earthquake. Compared with the periodic changes of 1 to 2 days before the earthquake, several low-frequency ground pulsation waveforms are found, which are: characteristic ground pulsation (I) (3 to 6 seconds), characteristic ground pulsation (II) (20 to 30 seconds), and characteristic ground pulsation (III) (30 to 50 seconds). The characteristic pulsation wave is obviously different from the pulsation wave caused by other natural small earthquakes, distant earthquakes and typhoons (7 to10 seconds). The period, wavelength and amplitude of characteristic pulsations are measured, after calculation and analysis, it shows that the energy difference between these characteristic ground pulsations is very large, the maximum amplitude of the characteristic ground pulsation (I), the characteristic ground pulsation (II) and the characteristic ground pulsation (III) is 10−2, 10−9, and 10−23 times of the normal pulsation wave, respectively. The characteristic pulsation waves recorded 2 hours before the earthquake and 10 minutes apart at the main stations in Sichuan and its surrounding areas are mapped on the map. They appear as abnormal fluctuations that change continuously at any time near the epicenter, and appear along the seismogenesis fault one minute before the big earthquake. The spatiotemporal dynamic analysis of characteristic pulsation waves may provide important information before the earthquake.