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EARTHQUAKE ›› 2013, Vol. 33 ›› Issue (1): 12-21.

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Relocation of Small Earthquakes in North China Using Double Difference Algorithm

ZHAO Bo1,2, GAO Yuan2, SHI Yu-tao2   

  1. 1. China Earthquake Networks Center, Beijing 100045, China;
    2. Institute of Earthquake Science, CEA, Beijing 100036, China
  • Received:2012-07-12 Revised:2012-10-12 Online:2013-01-31 Published:2020-10-16

Abstract: North of Huabei region is the junction of three tectonic elements which are Huabei subsidence, Yanshan uplift, and Taihang uplift. This region is strongly active. Zhangjiakou-bohai seismic belt is in the north of this region, and Shanxi seismic belt is in the west. Using double difference algorithm, earthquakes occurred from 2006 to 2009 are relocated. The results of relocation show that many earthquakes distribute in the Zhangjiakou-bohai seismic belt, and the direction is WNW. The depth of the earthquakes distribution is from 0 to 20 km with a proportion of 96.3%. And the depths of 57.5% earthquakes are above 10 km in the upper crust. Thangshan region is active, and the distribution of the earthquakes is closely related to seismic faults. In the middle of Huabei subsidence, Xingtai region is also active. In this region, the depth of Xinhe fault can reach to Moho. There is abnormal velocity region, in which the distribution of earthquakes is separated into two parts. The distribution of earthquakes is tilted from northeast to southwest, and the focal depth becomes deep gradually.

Key words: Seismicity, Double different algorithm, Zhangjiakou-bohai seismic belt, Huabei region

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