基于我国高速铁路沿线路排列的原位地震监测网络所必需的单台站预警模式,提出适合高速铁路单台站快速准确地震预警的P波与S波复合自动快速识别的理论方法。首先通过极化分析方法分离P波和S波;然后利用改进的短时窗信号平均值与长时窗信号平均值之比的方法初步确定P波与S波的到时范围;最后通过改良的基于高阶统计量的赤池信息量准则算法推导P波与S波的精确到时。整理和分析具有代表性的2008年汶川Ms8.0级地震的主震及余震记录1 548条,以此对该理论方法进行综合验证。通过计算震相拾取率与偏差可知,与既有的方法相比,该理论方法可以实时、准确、快速、有效地对具有复杂的震源、传播路径以及场地效应的地震进行预警,能够满足高速铁路单台站地震预警的严格要求。
Based on the model of the earthquake early warning(EEW)for high speed railway using single station required by the seismic network along the railway line,we proposed a theoretical method of autorapid P and S waves recognition in EEW for high speed railway.Firstly P and S waves were separated through polarization analysis;then we applied an improved short term average/long term average characteristic function to obtain the preliminary picks;and finally aprecise P and S phase arrival time was determined in terms of the Akaike information criteria(AIC)algorithm of the higher order statistics.We tested our techniques to the main-shock and aftershocks of the 2008 Ms8.0 Wenchuan earthquake,where 1548 waveforms were treated.In comparison to other methods according to the seismic phase picking rate and the deviation,the proposed theoretical method was of accuracy,speediness,effectiveness and could be applied for the real time early warning of impending earthquakes occurred with diverse focal mechanisms,complicated propagation processes and site effects,which could fulfill the requirement of the EEW for high speed railways by single station.