云南地区3次6级间歇性双震第二主震的前震特征分析  

Analysis on Foreshock Features of the Second Mainshocks in Three Groups of Intermittent-type Double Shocks with M≥6 in Yunnan

作　　者：李永莉[1] 苏有锦[1] 田秀美[1] 钱晓东[1] 

机构地区：[1]云南省地震局,昆明650041

出　　处：《地震研究》2005年第2期114-118,共5页Journal of Seismological Research

基　　金：云南省"十五"重大项目--云南地震预测预报实用化技术系统建设;国家"十五"科技攻关项目(2004BA601B01-04-02)资助.

摘　　要：分析大姚6.2,6.1级间歇性双震地震序列的地震波、地震活动变化,以类比方法分析了同震型的1976年盐源—宁蒗6.7,6.4级地震序列,1971年普洱6.7,6.2级地震序列,寻求第二主震的前震活动特征,结果表明:大姚6.2级与盐源—宁蒗6.7级序列中均出现一组P,S波振幅比为直线的前震;双震序列在第一主震后20～60d内,出现3,4级地震频度增高与b值、h值偏离余震衰减准同步异常的现象,第二主震临震前数天出现3,4级地震平静,与第二主震时间间隔仅2～9h,相距震中8km内发生3级显著地震。为预测预报间歇性双震序列的第二主震提供了一定判据。Through comparing and analyzing the seismic wave and seismicity variation of three groups of intermittent-type double shock sequences, the 2003 Dayao M6.2, 6.1, 1976 Yanyuan-Ninglang M6.7, 6.4, 1971 Pu’er M6.7, 6.2 earthquake sequences, we studied the foreshock features of their second mainshocks. It is found that there existed a group of foresocks, the amplitude ratio of P wave to S wave of which is a direct line, in the Dayao and Yanyuan-Ninglang earthquake sequences. For every double shock sequence, in 20-60 days after the first main shock, the M3-4 events rose and b-value and h-value deviated to the normal value of the sequence; but in several days before the second mainshock, the M3-4 events were calm; until 2-9 hours before the second mainshock, there was obvious M3 earthquake occurred within 8km from the first epicenter. These foreshock features can provide some opinion for predicting the second mainshock of intermittent-type double shocks.

关 键 词：6级间歇性双震 第二主震 前震特征 云南地区 

分 类 号：P315.75[天文地球—地震学]