北天山地区部分中强震前小震震源深度变化特征

利用双差定位法修订后的新疆北天山地区地震目录, 以1990年以来该区发生的8次7组5级以上中强地震作为震例样本, 分析研究主震前震源附近区域小震震源深度的变化特征。 研究结果显示, 在研究时段内7组地震中6组地震前出现小震震源深度趋深变化的异常图像。 类似异常图像共出现9次, 异常对应率66.7％。 这种异常图像可为地震预测综合判定提供参考依据。

Change feature of source depth of small earthquakes before some Moderately strong earthquakes in the Northern Tienshan region

The article analyzes the change feature of source depth of small earthquakes around the source regions before mainshocks with 8 moderately strong earthquakes with magnitude greater than 5 in 7 groups from the seismic catalogue in the northern Tienshan region corrected with double-difference location method.The result shows that there exists anomalous trend change of source depth of small earthquakes before six ones of seven groups' earthquakes.There are 9 similar abnormal change images with corresponding ratio of 66.7 per cent.The anomalous image offers reference criteria for comprehensive judgment of earthquake prediction.