涿鹿4.3级地震前后应力场变化特征

采用目前普遍接受的基于初动符号和振幅比的HASH方法,计算了2008年10月至2018年10月张渤带西段中小地震震源机制解;在获得震源机制解的基础上,进一步利用震源机制解一致性参数研究了涿鹿4.3级地震前后的应力场变化特征。结果表明:该区域震源机制解以正断型和走滑型为主,逆冲型次之,涿鹿4.3级地震后走滑型地震较震前略有上升,表明该区域的剪切作用增强;主压应力轴方位大致为NEE-SWW,主张应力轴为SSENNW向;涿鹿4.3级地震发生在震源机制一致性参数的低值边缘附近,发震时间也在一致性参数的低值时段。

Dynamic Change of Stress Field Inverted Using Focal Mechanisms before and after the Zhuolu M_S4.3 Earthquake

In this paper, the focal mechanisms of small and moderate earthquakes which occurred in the west of Zhangbo seismic zone from October 2008 to October 2018 were inverted by using the Hash method which is popular in the modern international based on the first motion sign and amplitude ratio.Based on the obtaining focal mechanism solution, the variation characteristics of stress field before and after the Zhuolu M S4.3 earthquake are further studied.The results show that the focal mechanism solutions in this region are mainly normal and strike-slip type, followed by reverse strike type, and the strike-slip type slightly increases after Zhuolu M S4.3 earthquake compared with before the earthquake, indicating that the shear effect in this region is enhanced.The compressive stress axes is predominated NEE-SWW and the principal tensioning stress axes bearing is SSE-NNW.The zhuolu M S4.3 earthquake occurred near the low-value edge of the consistent parameters of the focal mechanism.