用和达法计算河北及邻区地震波速比并按照不同震级不同窗口作滑动平均。通过对唐山地区波速比变化特征与中强地震对应关系的定性分析，发现M_L ≥ 1.5地震波速比曲线与M_L ≥ 4.0的地震对应较好，提出异常指标进行定量统计得到该区波速比异常与地震的对应关系和预报效能；按照同样的思路对河北另外3个地区进行分析，发现各分区波速比异常既有共性特征也有差异。

In this article we use the earthquake data in Hebei Province and its adjacent area to calculate the average wave velocity ratio,and scan the results with different window size and length. By analyzing the characteristics of the curve in different regions,we can find that there is a better corresponding relation between the curve of M_L1.5 and moderate earthquake. So,we extract the abnormal index to calculate the prediction efficiency for the four areas.

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河北省科技支撑计划项目：河北震后快速响应辅助决策系统建设（15275402D）、河北省地震局地震科技星火计划重点项目“晋冀蒙交界区临时测震台网建设运行及强震背景跟踪研究（DZ20150428102）”河北省地震局科技星火计划“基于CAP方法反演河北地区中等地震震源机制的研究（DZ20150417012）”共同资助