Abstract In order to explore their seismogenic structures and their genesis, based on the observation data of the Beijing-Tianjin-Hebei Seismic Network, we use the CAP method to invert the focal mechanism solutions and centroid depths of the Luanzhou MS4.3 earthquake, the Changli MS4.2 earthquake and their MS3.3 aftershocks. We use the local seismic depth phase sPL to obtain more accurate moments. According to the depth of the center, combined with the double-difference positioning method, we obtain the source distribution results of the two sequences, and analyze the seismogenic structure and genetic correlation. The results show that: 1) The strike, dip and slip angles of nodal plane Ⅰ of the Luanzhou MS4.3 earthquake are 211°, 85°, and 168°, respectively, and nodal plane Ⅱ are 302°, 78°, and 5°, respectively. It is a strike-slip type, the focal depth is 8 km, the focal distribution of the earthquake sequence is NNE, and the short-axis section seismic distribution shows a near-vertical dip and a high dip angle. It is considered that the seismogenic fault plane is a nodal plane Ⅰ. The nodal plane Ⅰ of the aftershocks are 189°, 68°, 161° and 190°, 61°, 170° respectively; the nodal plane Ⅱ are 286°, 72°, 23° and 285°, 81°, 29°, respectively. The focal dislocation type is both strike-slip type, the focal depth is 10.5 km, the focal distribution of the earthquake sequence is NNE direction, the short-axis section shows a near-vertical dip, high dip angle, and the seismogenic fault plane is considered to be the nodal plane Ⅰ. 2) Based on the source parameters of the Luanzhou MS4.3 earthquake, the Changli MS4.2 earthquake and the Luanzhou MS7.1 earthquake, combined with regional geological structural data, we believe that the seismogenic structures of these three earthquakes are not preexisting in the shallow crust. It may be related to the low-velocity layer in the crust in the source area, and the interlaced inclusions of high-velocity and low-velocity bodies in the crust are the common basis for these earthquakes.
LI He,DONG Yibing,WANG Yixi. Research on the Source Parameters and Tectonic Significance of the 2021 Luanzhou MS4.3 Earthquake and the 2015 Changli MS4.2 Earthquake[J]. jgg, 2022, 42(12): 1281-1287.
LI He,DONG Yibing,WANG Yixi. Research on the Source Parameters and Tectonic Significance of the 2021 Luanzhou MS4.3 Earthquake and the 2015 Changli MS4.2 Earthquake[J]. jgg, 2022, 42(12): 1281-1287.