2020年7月12日河北唐山M_(S)5.1地震发震构造及唐山断裂带三维模型

The Seismogenic Structure of the Hebei Tangshan Ms5.1 Earthquake on July 12,2020 and Three-dimensional Modeling of Tangshan Fault Zone

基于2020年7月12日河北唐山M_(S)5.1地震事件,以河北省测震台网测定的唐山5.1级地震序列目录中M_(L)1.0以上地震事件为模板,采用匹配滤波技术对2020年07月12—16日的连续波形进行遗漏地震检测,并确定遗漏地震的发震时刻,进一步完善地震序列目录;计算了主震的震源机制解,得到节面I:走向236°/倾角77°/滑动角−170°,节面Ⅱ:走向143.7°/倾角80.3°/滑动角−13.2°;地震事件经震相到时校正后,采用双差定位方法进行精定位,重定位后的余震序列优势分布方向为NE向,结合发震构造背景,震源机制解节面Ⅰ与唐山-古冶断裂东北段的走向、倾角大体一致,由此推测唐山-古冶断裂为河北唐山M_(S)5.1地震的发震断裂,节面I为同震破裂面;最后,基于SKUA-GOCAD软件,对发震断裂进行了三维模型的初步模拟和刻画,作为辅助工具为判定该地震的发震构造提供了更为直观的依据支撑。

Taking the waveform data of earthquakes above M_(L)1.0 in the sequence catalogue of the Hebei Tangshan Ms5.1 earthquake on 12 July 2020 recorded by Hebei Digital Seismic Network as templates,the missing seismic detection is carried out on the continuous waveform from July 12 to 16,2020 by using the matched filtering technology to detect the missing earthquakes in the earthquake sequence.The original time of the earthquakes are determined to improve the earthquake catalog.The focal mechanism solution of the main earthquake is calculated,and the parameters of the nodal plane I are:strike 236°/dip angle 77°/rake angle−170°while the parameters of the nodal planeⅡare:strike 143.7°/dip angle 80.3°/rake angle 13.2°.After time correction of seismic phase,the double difference location method was used to accurately relocate the seismic events.The dominant distribution direction of aftershock sequence after relocation was NE direction.Combined with the seismogenic tectonic background,The nodal surfaceⅠof focal mechanism is roughly consistent with the strike and inclination of the northeast section of Tangshan-Guye fault.Therefore,it is speculated that the Tangshan-Guye fault may be the seismogenic fault of the Tangshan Ms5.1 earthquake,the Nodal plane I may be the co-seismic rupture plane.Finally,using the SKUA-GOCAD software,the 3 d model of the seismic fracture is preliminarily simulated and depicted.As an auxiliary tool,it provides a more intuitive basis for judging the fault of the earthquake.