【摘要】 通过对2008年1月至2013年10月四川省长宁地区ML≥3.5的20个近震重新进行分析后发现,在ML≥4.0时,该地区近震面波发育,ML震级略大于MS震级;100~160 km以内的部分台站即可清晰记录到上地壳绕射波Pb,也可清晰记录到下地壳反射波Pm P;在研究时间段内,该地区仅发生1次ML≥5.0地震,用波形记录测定出有两个不同的破裂点。更多还原

【Abstract】 According to the seismic phase observation data of 20 near earthquakes of ML≥3. 5 occurred in Changning area,Sichuan Province,between January 2008 and October 2013,we summarize the law of seismic wave phases. In Changning area the seismic surface wave of near earthquakes are rich and the seismic magnitude determined from the body wave is slightly larger than the magnitude determined from surface wave. The seismic waves Pm P refracted from the upper crust and lower crust interfaces are observed clearly by stations located within radius range from 100 to 180 km. During the study period,only one ML≥5. 0 earthquake occurred in the area,two epicenters were determined by the seismic wave form recording.更多还原