摘要
2021年11月17日江苏盐城近海区域发生MS5.3地震,该地震的发震机制及其原因引起地球科学家的广泛关注,为分析地震发生的原因,本次地震的震源机制解和区域应力场的精确确定是必要的。本研究综合多种机构的震源机制解数据确定了可信的震源机制中心解。为保证震源区域应力场求解的精度,本文搜集了地震周围2016年以前的历史震源机制解数据,并利用地震观测报告,得到22个2016年之后地震的震源机制解,使用结合后的震源机制解数据求解了江苏盐城海域MS5.3地震周围的应力场。最终结果为:江苏盐城海域MS5.3地震的震源机制中心解节面Ⅰ走向104.95°,倾角70.91°,滑动角26.45°,节面Ⅱ走向5.70°,倾角65.11°,滑动角158.86°;研究区域的主压应力呈ENE-WSW向分布,主张应力呈NWN-SES向分布。将应力场投影到震源机制中心解节面上,发现两个节面均处于相对剪应力很高的水平,说明此次地震是在构造应力场作用下发生在剪应力最大释放节面上的地震,是应力积累后的一次正常释放,周边再次发生大地震的可能性减小。考虑到应力场投影到节面Ⅱ的相对剪切应力较节面Ⅰ大,并且节面Ⅱ与苏北—滨海断裂走向更为接近,确定节面Ⅱ为本次地震的发震断层面。
On November 17,2021,an MS5.3 earthquake occurred in the offshore area of Yancheng,Jiangsu Province,China.The seismogenic mechanism and its causes have attracted extensive atten-tion of earth scientists.To analyze the causes of the earthquake,it is necessary to accurately determine the focal mechanism solution of the earthquake and the regional stress field.In this study,a credible central focal mechanism solution was determined by synthesizing the focal mechanisms of various insti-tutions.To ensure the accuracy of solving the stress field in the source region,this study collects the historical source mechanism solution data around the earthquake before 2016,and uses the earthquake observation report to obtain 22 source mechanism solutions after 2016.The combined source mecha-nism solution data is used to solve the stress field around the MS5.3 earthquake in Yancheng Sea,Ji-angsu Province.The final results are as follows:the central focal mechanism of MS5.3 earthquake in Yancheng Sea area of Jiangsu Province plane I strike angle is 104.95°,dip angle is 70.91°,slip angle is 26.45°,plane II strike angle is 5.70°,dip angle is 65.11°,slip angle is 158.86°;The predominant di-rection of main compressive stress in this area is ENE-WSW,and the dominant direction of stress is NWN-SES.Projecting the stress field onto the central focal mechanism′s planes,both of planes are at a high level of relative shear stress,indicating that the earthquake occurred at the maximum shear stress release plane under the action of the tectonic stress field.It is a normal release after stress accu-mulation,and the possibility of a large earthquake occurring around is reduced.Considering that the relative shear stress projected by the stress field to Ilane II is larger than that of Plane I,and Plane II is closer to the strike of the Subei-Binhai fault,it is determined that the plane II is the seismogenic fault plane of this earthquake.
作者
黄少华
万永革
孙业君
许鑫
余海琳
冯淦
李枭
HUANG Shaohua;WAN Yongge;SUN Yejun;XU Xin;YU Haiin;FENG Gan;LI Xiao(Institute of Disaster Prevention,School of Earth Sciences,Sanhe 065201,China;Hebei Key Laboratory of Earthquake Dynamics,Sanhe 065201,China;Earthquake Administration of Jiangsu Province,Nanjing 210014,China)
出处
《防灾减灾工程学报》
CSCD
北大核心
2023年第6期1266-1274,共9页
Journal of Disaster Prevention and Mitigation Engineering
基金
中央高校科研业务费专项(ZY20215117)
国家自然科学基金(42174074,41674055)资助。
关键词
2021江苏盐城大丰海域地震
震源机制中心解
P波初动
应力场
发震构造
the 2021 Jiangsu Yancheng Dafeng offshore earthquake
central focal mechanism solu-tion
P wave initial motion
stress field
seismogenic fault structure
