2012年河北唐山4.8级地震前后波速比变化特征

Variation Characteristic of Wave Velocity Ratio before and after Hebei Tangshan M_S4.8 Earthquake in 2012

选取河北数字地震遥测台网2008年1月至2018年4月产出的唐山震区范围内地震观测报告数据,利用单台和多台和达法对2012年5月河北唐山4.8级地震前后波速比进行计算。结果显示:单台和达法波速比计算得出陡河台等7个台站在唐山4.8级地震前存在低值异常;多台和达法计算波速比在ML≥1.0、ML≥1.5,ML≥2.0不同震级的波速比变化曲线与唐山4.8级地震对应较好,震前存在近一年的波速比低值变化。

Based on the observation report of seismic phases recorded by Hebei Digital Seismic Network from Jan.2008 to Apr.2018,we analyze the variation of wave velocity ratio before and after the 2012 Tangshan M_S4.8 earthquake using the Wadati method of single station and the multiple-station.The result shows a low value anomaly existing before the earthquake in Douhe and other 7 stations with Wadati method of single station.The wave velocity ratio of ML≥1.0,ML≥1.5,ML≥2.0 and different magnitudes calculated by Wadati method of multiple-station corresponds well to the Tangshan MS4.8 earthquake.There is a low wave velocity ratio anomaly existing nearly one year before the earthquake.