华北北部地区现今应力场时空变化特征研究  

Temporal and spatial variation characteristics of present stress field in the northern area of North China

作　　者：李瑞莎[1,2] 崔效锋[1] 刁桂苓[3] 张红艳[1] 

机构地区：[1]Institute of Crustal Dynamics,China Earthquake Administration [2]Second Crust Monitoring and Application Center,China Earthquake Administration [3]Earthquake Administration of Hebei Province

出　　处：《地震学报》2008年第6期570-580,共11页Acta Seismologica Sinica

基　　金：中央级公益性科研院所基本科研业务费专项(ZD2007-1-6);国家重点基础发展计划(973计划)课题(2006CB202203)共同资助

摘　　要：From focal mechanism solutions of the earthquakes in the northern part of North China during the period of 2002～2006,the directions of principal stress axes in 4 stress sub-districts are analyzed using a grid test method.The characteristic of present crustal stress directions is discussed.Based on this result and on the focal mechanism solutions calculated for some events in the period of 1977～1998,in combination with some other study results,the temporal variation of present crustal stress directions in the northern part of North China is investigated.The re-sults confirm that the direction of crustal principal stress in some regions had somewhat rotated after the 1976 Tangshan M7.8 earthquake.The mean P axes of the focal mechanism solutions rotated clockwise not only in Tangshan sub-district,but also in Beijing and Xingtai sub-districts after the Tangshan earthquake.In Beijing and Xingtai sub-districts the orientations of principal stress axes in the period of 2002～2006 are consistent with that before the Tangshan earthquake,implying that the stress orientations has rotated back to the state before the Tang-shan earthquake in these two sub-districts.The directions of the mean P axes are nearly E-W in Tangshan sub-dis-trict since the M7.8 earthquake.The present stress field in the sub-district northwest to Beijing,or in the western part of the Zhangjiakou-Bohai fault zone,is relatively stable during the time period concerned in this study.Because of the limitation of data,this paper only states a possible variation of stress field in the northern part of North China in the recent decades.From focal mechanism solutions of the earthquakes in northern part of North China during the period of 2002--2006, the directions of principal stress axes in 4 stress sub-regions are analyzed using a grid test method. The characteristics of present crustal stress directions is discussed. Based on this result and on the focal mechanism solutions calculated for some events in the period of 1977--1998, in combination with some other study results, the temporal variation of the present crustal stress directions in northern part of North China is investigated. The results confirm that the direction of crustal principal stress in some regions had somewhat rotated after the 1976 Tangshan M7.8 earthquake. The mean P axes of the focal mechanism solutions rotated clockwise not only in Tangshan sub-region, but also in Beijing and Xingtai sub-region after the Tangshan earthquake. In Beijing and Xingtai sub-region the orientations of principal stress axes in the period of 2002--2006 are consistent with that before the Tangshan earthquake, implying that the stress orientations has rotated back to the state before the Tangshan earthquake in these two sub-regions. The directions of the mean P axes are nearly E-W in Tangshan sub-region since the M7. 8 earthquake. The present stress field in the sub-region northwest to Beijing, or in western part of the Zhangjiakou-Bohai fault zone, is relatively stable during the time period concerned in this study. Because of the limitation of data, this paper only states a possible variation of the stress field in northern part of North China in recent decades.

关 键 词：震源机制解 华北地区 应力场 

分 类 号：P315.727[天文地球—地震学]