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

Taking the waveform data of earthquakes above M_L1.0 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 plane Ⅱ are: 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 surface Ⅰ of 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.