摘要
An earthquake measuring 5.1 on the Richter scale struck Wen'an county,Hebei Province on July 4,2006. No casualties have been reported,with only slight damage. The disaster level of this event is the slightest on the M4.9～5.1 events record tally since the CCDSN (China Center of Digital Seismic Network) was built in 1999. The epicenter intensity of this earthquake was low,while in areas like Beijing,which is 100km far away,abnormal high intensity zones appeared. This article discusses the reasons behind this abnormal phenomenon,with the diagrams of intensity isolines drawn by the intense seismic stations and networks in the capital circle area as references,as well as the seismogenic mechanism in the source,the seismic histories,the geological structures and the ray pathways of seismic waves in areas within 150km around the epicenter. It was concluded that the special dynamic and geological situations were the main causes for the lower intensity degree and slight damage in the epicenter area,but higher intensity in the surrounding areas.
An earthquake measuring 5.1 on the Richter scale struck Wen＇an county, Hebei Province on July 4,2006. No casualties have been reported, with only slight damage. The disaster level of this event is the slightest on the M4.9 ~ 5.1 events record tally since the CCDSN （ China Center of Digital Seismic Network） was built in 1999. The epicenter intensity of this earthquake was low, while in areas like Beijing, which is 100km far away, abnormal high intensity zones appeared. This article discusses the reasons behind this abnormal phenomenon, with the diagrams of intensity isolines drawn by the intense seismic stations and networks in the capital circle area as references, as well as the seismogenic mechanism in the source, the seismic histories, the geological structures and the ray pathways of seismic waves in areas within 150km around the epicenter. It was concluded that the special dynamic and geological situations were the main causes for the lower intensity degree and slight damage in the epicenter area, but higher intensity in the surrounding areas.
基金
funded by the project "Demonstration of typical changes of vulne rability of disasters in urban-rural fringe:a case study of seismic disaster in the Beijing-Tianjin-Tangshan region" of National Natural Science Foundation (Grant No.40771011)
