摘要
通过与更早地震资料的对比,研究了鲜水河断裂带,川滇地壳块体东带、西带,松潘、龙门山断裂带以及整个川滇地区较长时间尺度的地震活动盛衰交替性。结果表明,川滇东带北段(鲜水河断裂带)、松潘、龙门山地震带及川滇西带中段和南段(主要是红河断裂带)的地震活动具有明显的几十到百年尺度的盛衰交替性。而川滇东带中南段(安宁河-则木河-小江断裂带)与川滇西带北段(金沙江断裂带)在上述地震带的平静期里,中强以上地震频次明显减少,但有个别7级以上强震发生。这样,整个川滇地区地震活动的盛衰交替性呈现一种比较复杂的阶段性特征:伴随频繁中强震的强震活跃期与突发强震活动期交替出现。值得注意的是,川滇地区从19世纪末开始的伴随频繁中强震的强震活跃期已超过百年,目前出现长期平静,应注意进入突发强震活动期的可能性。根据川滇地区上一个突发强震活动期突发强震的空间分布,推测未来的突发强震可能发生在南北向断裂带,或其他方向断裂带与南北向断裂带的交汇部。文中还对上述统计现象的机理作了简要讨论。
Comparing with earlier seismic data, alternation between seismically active and quiescent periods with longer time scale for Xianshuihe faults, west and east zones of Sichuan-Yunnan crustal block, Songpan-Longmenshan faults, and whole Sichuan-Yunnan area was studied. The results indicated that there was obvious alternation between seismically active and quiescent periods with longer time scale in north section of east zone of Sichuan-Yunnan block (Xianshuihe faults), Songpan-Longmenshan faults, and middle and south section of west zone of Sichuan-Yunnan block (Honghe faults), there was a decrease in moderate earthquakes but a few strong earthquakes M≥7 in middle and south section of east zone of Sichuan-Yunnan block (Anninghe-Zemuhe-Xiaojiang faults) and north section of west zone of Sichuan-Yunnan block (Jinshajiang fault) during the quiescent periods of above faults. Therefore, there were complicated stage characteristics for alternation between seismically active and quiescent periods in whole Sichuan-Yunnan area: strong seismic active periods accompanied with many moderate earthquakes and sudden seismic active periods in which a few strong earthquakes suddenly occurred alternately appear. It should be noticed that strong seismic active period accompany with many moderate earthquakes from the end of 19th century in Sichuan-Yunnan area has lasted beyond 100 years, there has been a long time quiescence up to now, and a sudden seismic active period may come. From distribution of sudden strong earthquake of last sudden seismic active period in Sichuan-Yunnan area, it could be inferred that next sudden strong earthquake probably will occur along some faults with strike NS or along some convergent zones of faults with strike NS and other faults. The mechanism of the above-mentioned statistical phenomena was briefly discussed in this paper.
出处
《地震》
CSCD
北大核心
2005年第1期51-57,共7页
Earthquake
基金
地震科学联合基金老专家预报专项(304014)
