摘要
By use of the arrival times and waveform of the earthquakes recorded by the seismic network of the capital circle and digital seismic array operated by the Institute of Geomechanics,CAGS in the period from December of 2008 to November of 2011,we accurately relocated earthquakes by the method of double-difference combining cross-correlation and Geiger method respectively.The location and distribution of hypocenters demonstrate that there are four seismic belts and two seismic clusters in the northwestern Beijing.These seismic clusters are located in the intersection between northeastward seismic belt and northwestward seismic belt and they may be caused by the activities of Dongbeiwang fault and the Nankou-Shanqian fault.The focuses were at the depths of about 5 30 km,and the earthquakes occurred in the northwestern Beijing were mainly located in the upper and middle crust.