Monitoring and Research of the 2007 Ning'er,Yunnan,M_S6.4 Earthquake

On June 3,2007,a MS6.4 earthquake occurred in Ning'er,Yunnan. We accurately located the earthquake using the data from the temporal seismic network in the Ning'er seismic area,gave the source parameters of the main shock and aftershocks combining with the seismic wave data from Yunnan Regional Digital Seismic Network,and analyzed the source process of the Ning'er earthquake. The seismogenic structure of this earthquake is a NW-trending fault. The strike of main rupture is about N50°W,the dip direction is in SW,the dip angle is about 80° and it is a strike-slip fault. The rupture length is about 30 km,the width is about 5 km and the depth of the rupture surface is 2-12 km. The strike of the fault is almost the same as the direction of long axis of the macroscopic isoseismals. The source parameters reveals that the seismic moment in the Ning'er seismic area is about 1,012-1,018 N·m,the rupture radius of the source is 300-3,500 m and the stress drop is 0.0044-14 MPa. The events with high stress drop mostly occurred in the depth of 4-10 km,which indicates that this depth range is the mainly active area of the Ning'er earthquake. The stress drop gradually decreases over time and the earthquake is mainshock-aftershock type.