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长期地震观测发现,北京地震台实际地震记录的震相走时与全球地震走时表IASP91之间存在走时偏差。结合北京地震台及周边地下40km精细速度结构的研究成果和AK135模型,构建其地震走时表的计算模型。通过对该地震台2003—2008年NCDSN地震观测实际走时比对,对模型结构进行修正,最终建立北京地震台地震走时表。从人工地震和天然地震的走时对比来看,该走时表精度比IASP91提高38%以上,近震表现尤为显著,比IASP91提高50%以上。
Basing on the long-term analysis of Earthquake,we found the seismic travel time have a little residuals between the IASP91 and the actual recording of BJT station. We established BJT model for computing seismic travel times which combined the velocity structure of BJT 40KM underground with AK135 model for the deeper than 40km. We used the real travel times from the recording of BJT station between 2003 and 2008 to modify this model .Ultimately , we have developed BJT travel-time tables. The results of comparing with natural earthquake and artificial earthquake, we found the precision of BJT travel timetable was over 38% higher than IASP91, especially near earthquake, the precision raised more than 50%.