Relocation of the Bachu-Jiashi, Xinjiang earthquake sequence in 2003 using the double-difference location algorithm

Combining the data recorded at the mobile seismic network with those from the regional network, we relocated the 404 aftershock sequence including 404 events of M-L >= 3.5 for the 2003 Bachu-Jiashi, Xinjiang M(S)6.8 earthquake by the double-difference method and made theoretical analysis of the feasibility. We got a result of significant improvement. Compared with the original result, the relocation makes the image of earthquake distribution become more convergent and more consistent with the intensity investigation and the source mechanism. The dominant distribution of focal depths is in the range 15 similar to 25 km and the result is more consistent with the local geologic setting that there is a low velocity sediment layer above the depth 10 km. The arrival time residuals reduce to 0.24s from 3.94s. The horizontal average error is estimated to be less than 1.1 km and the vertical average error can been controlled less than 2.4 km.