西藏地区强震活动趋势的初步研究

PRELIMINARY STUDY ON THE TREND OF STRONG EARTHQUAKE ACTIVITY IN XIZANG REGION

摘要:

根据1911~1994年地震资料,详细讨论了西藏地区强震活动分期、特征及其趋势,并应用统计方法分析研究了该区强震的时间分布规律和发震概率。结果表明,本世纪以来西藏地区经历了3个强震轮回,目前正处于第Ⅳ轮回平静幕结束、新的活跃幕即将开始之际,未来活跃幕内将出现数组地震丛集现象,1995~1996年发生M_S ≥ 6地震的累计概率为80%~87%,发生M_S ≥ 6.5强震的累计概率达60%~76%。

Abstract:

According to the seismic data from 1911 to 1994, division of seismic periods, seismicity features and the trend of strong earthquake in Tibet have been discussed in detail. Time distribution of strong earthquakes and the probability of occurrence have also been analysed by using statistical method. The results show that the region has gone through three strong-earthquake cycles since this century,and now it is between the end of the quiet episode and the beginning of the active episode in the 4th cycle. There will be several swarms here in the future. During 1995 and 1996, the occurrence probability of M_S ≥ 6.0 earthquake is 80%-87%, and that of M_S ≥ 6.5 earthquake is 60%-76%in Tibet region.