地震视应力在云南地震序列中的前兆特征  

PRECURSORY SPECIALLTIES OF APPARENT STRESSES IN YUNNAN EARTHQUAKE SERIES

作　　者：刘红桂[1] 刘杰[2] 丁页岭[3] 孙业军[3] 于昕[3] 

机构地区：[1]中国地震局地球物理研究所,中国北京100081 [2]中国地震台网中心,中国北京100036 [3]江苏省地震局,中国南京210014

出　　处：《地震学报》2006年第5期462-471,共10页Acta Seismologica Sinica

基　　金：国家自然科学基金项目(40574016);国家"十五"重点科技攻关项目(2004BA601B01-04-03);地震科学联合基金项目(104047);江苏省社会发展科技计划项目(BS2005069)联合资助

摘　　要：在假设震源位移谱符合ω平方模型的基础上,得到了利用震源位移谱低频水平与拐角频率来计算中小地震视应力值的数学表达式.采用数字化速度波形记录,通过校正仪器响应、介质衰减与吸收效应、台站场地响应等影响因素后,计算得到了云南地区4个地震序列共823次中小地震的视应力值.结果表明,地震视应力在云南地区的这4个地震序列中有很好的前兆特征表现,即:地震序列中只要发生了视应力值超过1MPa的中小地震,其后就一定会有中强震发生;如果序列中中强地震发生后再没有发生视应力值超过1MPa的中小地震,则该序列就不会有强余震发生.同时研究表明,4个地震序列所在地区的平均视应力值为0.8MPa,地震视应力值与地震震级没有显著相关关系.On the basis of the assumption that we model accords with source displacement spectra, we have obtained the mathematical expressions for calculating apparent stresses of moderate-small shocks from low frequency flat level and corner frequency. By using digital seismic records, apparent stress values are calculated for 823 moderate-small shocks of 4 earthquake series in Yunnan area following corrections for instrument response, propagation influence and site effect. The results show that for the 4 earthquake series in Yunnan area, apparent stress hints precursory information, which means that if a moderate small shock occurs with apparent stress larger than 1 MPa in an earthquake series, a moderate-strong earthquake will occur afterwards; and if there is no moderate-small shock with apparent stress larger than 1 MPa after a moderate-strong event in an earthquake series, strong aftershock will not occur. The research also indicates that the average apparent stress value is 0.8 MPa in Yunnan area, therefore, apparent stress is not obviously related to seismic magnitude.

关 键 词：视应力 ω平方模型 地震辐射能 地震矩 震源位移谱 

分 类 号：P315.727[天文地球—地震学]