Based on the phase observation report from Xinjiang regional seismic network,we use the finite difference tomography method to invert the P-wave velocity structure of the central and eastern segments of Xinjiang Tianshan mountain.We then acquire the half-annual scale for the evolution of P wave velocity structure before and after the Xinyuan-Hejing earthquake.The results show that the zone of high P-wave velocity difference is produced before the earthquake in the epicenter and the surrounding area at a depth of 12 km,with an anomaly amplitude up to 0.3 km/s.The apparent difference in speed reflects changes of the crust medium by half-annual scale of different time in the same depth of P-wave velocity differential analysis.%基于新疆区域地震台网记录的地震观测报告,采用有限差分层析成像方法反演新疆天山中东段地区的地壳P波速度结构,获得了2012年新源和静6.6级地震前后该区域12 km和24 km深度处半年尺度的P波速度结构的时间演化过程.结果表明,12 km深度处震前震源区及附近区域P波速度差在空间上形成NNE向变化剧烈的高值异常区,异常幅度达0.3 km/s.这种明显的速度差异表明,将半年尺度不同时间段相同深度的P波速度进行差分析,能较好地反映一定区域内地壳介质特性的变化.
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