云南地区地震视应力的时间和空间分布研究  

ON TEMPORAL AND SPATIAL DISTRIBUTION OF SEISMIC APPARENT STRESSES IN YUNNAN AREA

作　　者：秦嘉政[1] 钱晓东[1] 

机构地区：[1]云南省地震局,中国昆明650224

出　　处：《地震学报》2006年第3期221-229,共9页Acta Seismologica Sinica

基　　金：云南省重点科技攻关项目(NG2001)资助

摘　　要：利用地面运动峰值速度(r·v)测定地震波辐射能ER的方法,详细研究了云南地区中小地震和两次余震序列的地震视应力σa的时空分布.结果表明,视应力在空间分布上存在明显的非均匀性,高视应力集中区与中小地震活动频繁地区相关.在大姚6.2级主震前,视应力出现了高值变化时段,是平均值0.25MPa的5倍,且主震及周围地区具有相对较高的视应力值.因此,视应力的时空变化特征可作为地震危险性预测的一种新的判据,余震序列视应力σaA与主震视应力σaM之比一般小于1.0.The method of radiation energy ER of the earthquake wave measured by the peak velocity （r·v） of the ground motion is applied to a detaile study on the temporal and spatial distributions of the seismic apparent stresses （σa） for the moderate and small earthquakes and two aftershock sequences in Yunnan area. The results show that there exists an obvious non-homogeneity for the seismic apparent stresses in the spatial distribution. The concentrated regions of the high apparent stresses are related to the active places of the moderate and small earthquakes. Before the Dayao M=6. 2 earthquake, there was a period in which the apparent stresses were high and the value was 5 times of the average value, 0.25 MPa. The relatively high values of apparent stresses distribute around the epicentral areas of the major shock and nearby. It indicates that the variation characteristics of the apparent stresses can be taken as a new kind of criterion for the earthquake risk forecast. Usually the ratio of the apparent stresses of the aftershock sequence σaA to the ones σaM of major shock is less than 1.0.

关 键 词：地震能量 视应力 地震矩 时空分布 云南地区 

分 类 号：P315.727[天文地球—地震学]