地震学报（英文版）2008，Vol.21Issue(3)：243-257,15.
Temporal VP/VS variation characteristics in different zones of China's Capital Circle area before and after Wen' an earthquake
Temporal VP/VS variation characteristics in different zones of China's Capital Circle area before and after Wen' an earthquake
摘要
Abstract
On July 4, 2006, an earthquake of Ms5.1 took place in Wen'an, Hebei Province, just at the south center of China's Capital Circle area digital seismograph network. It is the strongest event recorded ever since the network went into operation in 2002. We processed the vast amounts of phase data yielded by the 107 digital seismic stations between 2002-2007 using Wadati method. In order to improve the precision and stability of shear and compressional wave velocities (vP/vS) calculation, we impose a number of restrictions on the computation environment and condition, e.g., the earthquakes are densely concentrated, selected stations are limited in range, the number of stations in-volved in the computation is larger than 5 and linear fitting features high precision and small error. Under these restrictions, the study shows that vP/vS in and around Wen'an and Tangshan underwent a normal-low-normal process one year before Wen'an earthquake, vP/vS became obviously low and the low ratio lasted for about one year, meanwhile, little variation of vP/vS was seen in Xingtai, northwest of Beijing, southwest of Beijing, Beijing-Tianjin and Beijing; after the quake, the vP/vS returned normal in Wen'an and Tangshan. Error and stability analysis of the calculated result for vP/vS shows it is convincible that anomaly appeared in and around Wen'an and Tangshan be-fore Wen'an earthquake.关键词
Wen'an earthquake/ ratio of shear and compressional wave velocities/ earthquake predictionKey words
Wen'an earthquake/ ratio of shear and compressional wave velocities/ earthquake prediction分类
天文与地球科学引用本文复制引用
WANG Lin-ying,GUO Yong-xia,LIU Fang,JIANG Chang-sheng..Temporal VP/VS variation characteristics in different zones of China's Capital Circle area before and after Wen' an earthquake[J].地震学报（英文版）,2008,21(3):243-257,15.基金项目
Special Fund for Basic Scientific Research, IGPCEA (DQJB06B03) and National Program for Key Science andTechnology Projects during the 11th Five-year Plan Period (2006BAC01B03-04-04).Contribution No.08FE3004, Institute of Geophysics, China Earthquake Administration. （DQJB06B03）
