Precursory specialties of apparent stresses in Yunnan earthquake series  

作　　者：刘红桂 刘杰 丁页岭 孙业军 于昕 

机构地区：[1]Institute of Geophysics,China Earthquake Administration [2]Earthquake Administration of Jiangsu Province,Nanjing 210014,China [3]China Earthquake Networks Center [4]Earthquake Administration of Jiangsu Province

出　　处：《Acta Seismologica Sinica(English Edition)》2006年第5期497-506,共10页

基　　金：National Natural Science Foundation of China (40574016), Key Project of State Science and Technology in the Eleventh Five-year Plan (2004BA601B01-04-03), Joint Seismological Science Foundation of China(104047)and Science and Technology Project of Social Development of Jiangsu Province (BS2005069).

摘　　要：On the basis of the assumption that ω^2 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 comer 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 not 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.On the basis of the assumption that ω^2 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 comer 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 not 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：apparent stress ω^2 model seismic radiant energy seismic moment source displacement spectra 

分 类 号：P315.727[天文地球—地震学]