1976年松潘7.2级地震前几种异常波形的记录特征及其在大震短临预报中的意义

WAVEFOR MANOMALY PRIOR TO THE SONGPAN EARTHQUAKE AND ITSVALUE TO SHORT-IMMINENT PREDICTION OF STRONG EARTHQUAKES

摘要:

本文研究了1976年松潘7.2级地震前,儿个台站记录到的异常地震波形的形态特征及时空分布特征。异常波形可分为4种形态;震中距小于80km的台站都不同程度地记录到了异常波形;临近地震时,记录中出现的波形数量增多,振幅增大;临震前10天波形密集,呈现明显的突跳变化。根据异常波形的特征,本文还对异常波形的物理机制进行了初步的研究,认为异常波形的出现是地震前孕震区岩石产生微破裂的结果。

Abstract:

This paper deals with the morphological features of waveform anomaly recorded at several stations before the M7.2 Songpan earthquake of 1976, and the space-time distribution fea-tures. The anomalous waveforms can be divided into four types: the anomalous waveforms were recorded in verying degrees at all stations (epicenter distance within 80 km); the numbers of the waveforms were increased during the approaching of the earthquake; the amplitude was en-larged; the waveforms were densified ten days before the earthquake with obvious skipping changes. Finally, according to the features of the waveform anomaly, the physical mechanism of the anomalous waveforms was studied preliminarily. It shows that the appearance of the wave-form anomaly results from the rock microfracturing in seismogenic area before the earthquake.