摘要
利用CAP方法反演了2010年6月5日阳曲MS4.6地震震源机制解,得到震级MW为4.5,节面I走向213°、倾角47°、滑动角-161°,节面II走向109°,倾角76°,滑动角-44°,属于倾滑型;精确定位显示震中处于石岭关隆起区,CAP反演和精定位结果推断本次地震的震源深度为17～20km。震源机制解节面参数与震中附近的山根底断裂和系舟山西麓断裂产状存在差异,这两条断裂不是阳曲地震的发震断裂,由于现场野外地质考察未发现地表断裂,不排除本次地震为隐伏断层活动的结果。
On June 5,2010,a magnitude Ms4.6 earthquake occurred in the Yangqu region,which was located on the Shilingguan uplift between the Taiyuan basin and the Xinding basin in the Shanxi rift.This was a moderately strong earthquake felt in Yangqu and surrounding areas.The earthquake ruptured on the Shangendi fault,which controlled the tectonic activities in the east side of the Taiyuan basin.Based on the seismicity distribution,it appears that this earthquake was also located in the seismic gap of the Taiyuan basin.To better understand the seismotectonics of this region,we relocated this event and further studied its focal mechanism based on the local broadband waveform data recorded by the regional seismic network in the Shanxi Province.In this work,the earthquake was initially relocated by means of the absolute relocating method,and then the focal mechanism and focal depth were determined by the ＂Cut and Paste＂ （CAP） method.We inversed the focal mechanism using waveforms in seven stations near the epicenter with high SNR ratios and clear P wave polarization,and the stations were evenly azimuthally distributed.The results of the focal mechanism and focal depth were testified by comparing the observed records and the synthetic waveforms.The results indicate that the Yangqu earthquake was a normal fault earthquake with a small percentage of strike-slip components.The best double couple solution is 213°,47°,and-161° for strike,dip,and slip angles,respectively,for one nodal plane,and 109°,76°,-44° for another.The moment magnitude was Mw 4.5,and the estimated focal depth was 17～20 km,as determined by the CAP method and absolute relocation method,which suggests that this event was a shallow earthquake.The focal depth of the Yangqu earthquake was consistent with the relocation of small to moderate earthquakes in the Shanxi rift.The Yangqu earthquake occurred about 6 km away from the Shangendi fault,which is the eastern boundary fault of the Taiyuan basin and is about 9.7 km away from the Xizhoushan-Xilu fault,
出处
《地震工程学报》
CSCD
北大核心
2013年第3期692-697,共6页
China Earthquake Engineering Journal
基金
山西省自然科学基金(2012011029)
山西省科技攻关项目(20100311129-220090311084)
中国地震局星火计划(xh1005xh12008y
xh13004)
关键词
阳曲4
6级地震
CAP方法
震源机制解
震源深度
发震断裂
Yangqu Ms4. 6 earthquake
Cut and Paste method
focal mechanism
focal depth
seismogenic fault
