地震工程学报2016，Vol.38Issue(2)：242-248,7.DOI:10.3969/j.issn.1000-0844.2016.02.0242
四川芦山7．0级地震前中小地震P轴方位角CV 值的变化
CV Value Variation of P-axis Azimuth for Small to Moderate Earthquakes before the Lushan MS 7 .0 Earthquake in Sichuan
摘要
Abstract
In the preparation process of a strong earthquake,at the potential source area and its vicinity, the tectonic stress field can be enhanced by local tectonic activities.There will be a space-time adj ustment of the stress field with the background of a stable regional stress field.To detect the crustal stress state of the study area,in this paper we analyze the focal mechanism data of small to moderate earthquakes that occurred at the epicenter of the Lushan MS 7 .0 earthquake and its surrounding areas more than ten years before the Lushan earthquake.We obtained the focal mechanism solutions of the small to moderate earth-quakes using the Hardebeck and Shearer (HASH)method,then used the CV value of the P-axis azimuth (the ratio of the standard deviation to its average)to identify the stress field change.The results show that the stress field obviously changed at the seismic source and its surrounding areas with time.The P-axis azimuth CV values of the small to moderate earthquakes exhibited a rise-decline-rise process prior to the Lushan M7 .0 earthquake,which means that there was a long period of stress accumulation before the M7.0 earthquake,consistent with the results of many previous studies.The CV values and apparent stress had the same tendency changes,which obj ectively reflect the changes in the stress field in the process of earthquake preparation.This study demonstrates that there is a certain relationship between the occurrence of strong earthquakes and the change in the P-axis azimuth CV values of small and moderate earthquakes.关键词
震源机制解/P轴方位角/CV 值Key words
focal mechanism solution/P-axis azimuth/CV value分类
天文与地球科学引用本文复制引用
郭祥云,陈学忠,李艳娥,王生文..四川芦山7．0级地震前中小地震P轴方位角CV 值的变化[J].地震工程学报,2016,38(2):242-248,7.基金项目
中国地震局行业专项（201408014）；中国地震局地球物理研究所基本科研重大专项 （）
