Application of Double-difference Relocation Technique Combined with Waveform Cross-correlation on Yingjiang Earthquake Sequence in 2011

Collecting and relocating 1 458 earthquakes in Yingjiang area from Dec. 10,2010 to Oct. 24,2011 by using double-difference method combined with waveform cross-correlation,the source parameter of 1 048 earthquake was obtained finally,and the statistical location errors( two times of mean square deviation) are 58 m in EW,34m in NS and 93 m in vertical direction respectively. The results show that:( 1) The relocated epicenter concentrated obviously,had a banding distribution in NE- SW( the length of band is about 10 km) and dominantly distributed in SSE trend.( 2) There was a significant difference in the epicenter distribution of foreshock and aftershock.The foreshock only distributed in both side of the Dayingjiang Fault and had a banding distribution in NE- SW trend,however the aftershock distributed not only along NE- SW trend but also migrated in SSE trend at the junction between the middle and the northeast segment of the Dayingjiang Fault.( 3) The phenomenon of main shock occurred near the junction of the fault and epicenter of foreshock jumped back and forth at the epicenter region,which might be caused by fault junction belonged to fragile area and the stress was easy concentrated. The obvious variation of focal mechanism of maximum aftershock and the new advantage distribution of the aftershock might reflect that the aftershock activity was under the control of the regional stress field and the local stress field caused by main shock.( 4) Under the controlling of the same stress filed,the distribution of the focal depths shows different segment characteristics along Dayingjiang Fault. The focal depth distributes in the range of 1 ~ 9 km at the southwest segment of AA' profile and northwest segment of BB' profile,however it mainly distributes in the range of 6~ 9 km at the northeast of AA' profile.