摘要
从地震学和地质学的角度探讨2019-12-26应城M_(S)4.9地震的发震构造。采用HYPO2000方法对地震序列进行重新定位,结果表明,余震主要分布在皂市断裂与长江埠断裂之间,总体呈NW向展布,与野外调查Ⅵ度烈度等震线长轴方向基本一致。采用kiwi波形拟合反演方法求解震源机制解,结果显示,主震破裂表现为走滑兼逆冲特征。节面Ⅰ走向NE,与震中以西的潜北断裂走向一致,但距离较远,且与该断裂的产状和受力方式不一致。节面Ⅱ走向NW,与皂市断裂和长江埠断裂相近。分析2条断裂的受力方式认为,在江汉盆地现今NWW向主挤压应力的控制下,皂市断裂与长江埠断裂均具有左旋走滑特征。由于2条断裂走向存在差异,在两者之间产生逆时针错转滑动,使得主震发震面走向处于2条断裂夹角中间方向;同时倾向也与实际断面存在差异,余震分布偏向主震东侧。综合分析认为,皂市断裂与长江埠断裂的构造活动共同引发本次应城地震序列。
We discuss the seismogenic structure of the Yingcheng M_(S)4.9 earthquake on 2019-12-26 from aspects of seismology and geology.The sequence is relocated by HYPO2000 method.The results show that aftershocks are mainly distributed between Zaoshi and Changjiangbu faults,and are distributed in NW direction,which is basically consistent with the long axis direction of the intensityⅥisoseismal in the field survey.The focal mechanism solution inverted by kiwi method shows that the main rupture is characterized by strike slip and thrust.The strike of planeⅠis NE,which is consistent with Qianbei fault in the west of epicenter,but it is far away,and it is not consistent with the occurrence and stress mode of the fault.The strike of planeⅡis NW,which is similar to Zaoshi fault and Changjiangbu fault.Through the analysis of dynamic mode of these faults,it is considered that under the control of NWW principal compressive stress in Jianghan basin,both Zaoshi fault and Changjiangbu fault are characterized by left-lateral strike slip.The strike of the main seismogenic plane is in the middle of two faults by an anticlockwise turn-slip due to the different strike.At the same time,the inclination of slip plane is also different with the actual fault plane,and aftershocks are partial to the east of the main shock.The analysis shows that the combined tectonic activity of Zaoshi fault and Changjiangbu fault triggered the Yingcheng M_(S)4.9 earthquake sequence.
作者
吴海波
陈俊华
王杰
WU Haibo;CHEN Junhua;WANG Jie(Key Laboratory of Earthquake Geodesy,Institute of Seismology,CEA,40 Hongshance Road,Wuhan 430071,China)
出处
《大地测量与地球动力学》
CSCD
北大核心
2021年第4期419-424,共6页
Journal of Geodesy and Geodynamics
基金
中国地震局地震研究所和中国地震局地壳应力研究所基本科研业务费(IS201826180)。
关键词
应城地震序列
矩张量反演
发震构造
sequence of Yingcheng earthquake
moment tensor inversion
seismogenic structure
作者简介
第一作者简介:吴海波,高级工程师,主要从事数字地震学与地下介质结构反演研究,E-mail:wuhaibo7777@163.com。
