新疆北天山地区M_S≥2.0地震震源参数的重新测定

Relocation of the M_S≥2.0 Earthqukaes in the Northern Tianshan Region,Xinjiang,Using Double Difference Earthquake Relocation Algorithm

基于新疆32个测震台站记录到的28701条P波和S波震相到时数据，利用双差地震定位法重新测定新疆北天山地区（42．5°-45°N，82°～89°E）1988年4月至2003年6月间发生的1348次Ms≥2．0地震的震源位置。为尽量得到全部地震的重新定位结果，本文结合双差地震定位法对资料的要求和所用资料情况，添加了437次1．5≤Ms〈2．0的地震震相到时数据参与定位计算。重新定位后得到了1253次Ms≥2．0地震的重新定位结果，占全部Ms≥2．0地震的93％，其中，Ms≥3．0的地震全部得到了重新定位结果，并对没有得到重新定位结果的95次2．0≤Ms〈3．0地震的原因进行了分析。得到重新定位结果的1253次地震的均方根残差的平均值由重新定位前的0．83s降到0．14s，震源位置的测定误差（2倍标准偏差）在E—W方向平均为0．993km，在N—S方向上平均为1．10km，垂直方向平均为1．33km。分析重新定位结果得出，重新定位地震的震源深度较定位前有明显收敛，集中分布在5—35kin，94．3％的地震震源深度分布在5—35km，68．2％的地震震源深度分布在10～25km，地震的平均震源深度为19km。

We applieded double different earthquake relocation algorithm to 1348 Ms ≥2.0 earthquakes occurred in the northern Tianshan region, Xinjiang, from April 1988 to June 2003, using total of 28701 P- and S- wave arrive time data recorded by 32 seismic stations in Xinjiang. Aiming to obtain most of these Ms ≥ 2.0 earthquakes relocations, and considering the requirement of the DD method and the condition of data, we added travel time data of another 437 events with 1.5 ≥ Ms 〈 2.0. Finally, we obtained 1253 of Ms ≥ 2.0 earthquake relocations, which accounts for 93 % of all the 1348 Ms 92.0 events and includes all the Ms ≥3.0 events. The reason of 95 events with 2.0≤ Ms 〈 3.0 being deleted during relocation was analyzed in the paper. After relocation, the RMS residual decreased from 0.83s to 0.14s, the average error is 0.993km in E-W direction, 1.10kin in N-S direction, and 1.33km in vertical direciton. The hypocenter depth are more convergent than before and distributed from 5 km to 35km, with 94% being from 5kin to 35km, 68.2% from 10km to 25kin. The average hypoecenter depth is 19kin.