Zhang K,Zhang F,Zhang H,Wang X,Hao M X,Zhai H. 2022. Matching location for small events and seismogenic fault of Aohanqi earthquake swarm of Inner Mongolia. Acta Seismologica Sinica,44(4):594−607. doi: 10.11939/jass.20210041
Citation: Zhang K,Zhang F,Zhang H,Wang X,Hao M X,Zhai H. 2022. Matching location for small events and seismogenic fault of Aohanqi earthquake swarm of Inner Mongolia. Acta Seismologica Sinica,44(4):594−607. doi: 10.11939/jass.20210041

Matching location for small events and seismogenic fault of Aohanqi earthquake swarm of Inner Mongolia

  • In Aohanqi area of Inner Mongolia, there occurred several clusters of small earthquakes during 2018−2019 and the waveforms of different earthquakes are overlapped with each other, which leads to the incompleteness of earthquake catalog. In order to solve this problem, we adopt the match and locate (M&L) method to identify, detect and locate the missing events in the catalogs, and then the focal mechanism solution of the largest event is analyzed by the CAP (cut and paste) method. The matched and located small earthquakes are used to fit parameters of seismogenic fault plane of the largest earthquake so as to determine the geometry of fault plane and seismogenic structure of Aohanqi earthquake swarm. The results show that by using the M&L method, we identified and located 405 small earthquake events, which are 5.4 times as much as the number of the original detected earthquakes, and the earthquake swarm extended predominately along the direction of NW−SE in the east of the intersection area between Hongshan-Balihan fault and Chifeng-Kaiyuan fault with focal depth mainly concentrating on 8−10 km. Besides, according to the fault fitting result of small earthquakes and the focal mechanism of the largest earthquake, it is concluded that the seismogenic structure of Aohanqi earthquake swarm is a concealed normal fault with sinistral strike-slip characteristics, which has a strike of 157° and a dip of 84°. Combined with the fault properties and activity characteristics of the Hongshan-Balihan fault and the Chifeng-Kaiyuan fault, it is deduced that the seismogenic fault of Aohanqi earthquake swarm may be formed by the interaction of the two deep and large faults in the continuous activities.
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