2001年四川雅江6级地震的前震与余震震源参数的变化  

CHANGES IN SOURCE PARAMETERS OF FORESHOCKS AND AFTERSHOCKS OF THE 2001 M_S6.0 YAJIANG, SICHUAN, EARTHQUAKE

作　　者：程万正[1] 陈天长[1] 魏娅玲[1] 朱航[1] 

机构地区：[1]四川省地震局,中国成都610041

出　　处：《地震学报》2003年第4期351-360,共10页Acta Seismologica Sinica

基　　金：国家重点基础研究发展规划项目<大陆强震机理与预测>( 95 130 5 0 5 )子课题资助

摘　　要：研究了 2 0 0 1年 2月四川省雅江县发生的MS5 .0前震、MS6 .0主震及序列地震的震源机制、波谱参数及应力降的变化过程与震区地震活动 .根据雅江地震的震源机制解 ,并结合余震空间分布图象分析 ,选雅江 5 .0级的节面Ⅰ为推测的地震断层 ,走向NNE ;选雅江 6 .0级地震的节面Ⅱ为推测的地震断层 ,走向WNW ,分析前震与主震的断层面走向是斜交的 .雅江 6 .0级地震发生前震区应力降水平有所增加 ,这一现象与震区地震活动的增加是一致的 .雅江地震序列的衰减起伏过程 ,前、余震波谱变化 。In this paper changes in focal mechanisms, parameters of wave spectra, and stress drops for the M S5.0 foreshock and M S6.0 mainshock in February 2001 in Yajiang County, Sichuan, and seismicity in epicentral region are studied. Comparison of focal mechanisms for the Yajiang earthquakes with distribution patterns of aftershocks the nodal plane 1, striking in the direction NNE, of the Yajiang M S5.0 event is chosen as the faulting plane; the nodal plane 2, striking in the direction WNW, of the M S6.0 event as the faulting plane. The strikes of the two faulting planes are nearly perpendicular to each other. The level of stress drops in the epicentral region before the occurrence of the M S6.0 earthquake increases, which is consistent with increase of seismicity in the epicentral region. The decay rate of the Yajiang earthquake sequence, changes in wave spectra for foreshocks and aftershocks, and focal mechanisms are complex.

关 键 词：四川 地震 序列特征 震源参数 雅江县 

分 类 号：P315.3[天文地球—地震学]