兴海6．6级地震前后地震波的变化

2000年9月12日在青海省海南州兴海县西南发生了6．6级地震。震后发现，青海省6个专业台站的地震波速比在震前出现了下降－低值－发震的过程。波速比空间分布在兴海地震前形成了一个椭圆形的异常分布区，异常波速比的地震占总地震的73％。另外，在武台的尾波持续时间在兴海地震前显示出了较为完整的异常过程。

VARIATION OF SEISMIC WAVE BEFORE AND AFTER XINGHAI EARTHQUAKE WITH Ms 6.6

WT5BZ]There occurred an earthquake with M s6.6 in Xinghai county in Qinghai province on Sept. 12,2000.The authors have found that V P/V S was in a drop-low-occur process in six professional stations before the earthquake.Spatial distribution of V P/V S formed an ellipse area,and the earthquakes of anomaly V P/V S were 73% of the total.The coda wave duration of Dawu was a complete anomaly process before the event.