一种地震P波和S波初至时间自动拾取的新方法

地震P波、S波初至时间的拾取是地震波分析的一项基础性工作.本文提出了一种新的地震波初至时间自动拾取的方法:首先,把地震波的三分量时程曲线变换为一组空间向的能量变化率时程曲线;然后对能量变化率时程曲线进行STA/LTA(Short Time Average/Long Time Average,短时间的均值/长时间的均值)处理,拾取地震P波和S波的大致初至时间;最后提出采用一种二次方自回归模型对初至附近的能量变化率曲线进行二次方自回归处理,精确拾取出P波和S波的初至时间.本文采用了10组芦山地震的记录数据和150组汶川地震的记录数据对此方法的可靠性进行了检验.以人工拾取结果为参考,此方法具有很高的准确率和稳定性,同时,相比于常用的STA/LTA方法和AIC(Akaike Information Criterion,Akaike信息准则)方法,此方法在计算时间效率方面稍微逊色,但是对S波初至时间的拾取精度和可靠性更高.此方法丰富了地震P波、S波初至时间的自动拾取方法.

A new method for picking up arrival times of seismic P and S waves automatically

To pick up the arrival times of seismic P-wave and S-wave is the foundational work of seismic analysis. This paper presents a new method to do it. Firstly, the time-history curves of three-component seismic waves are transformed into the corresponding spatial energy gradient curves. Secondly, the STA/LTA method is applied to the energy gradient curves to pick up the approximate arrival times of P-wave and S-wave. Lastly, based on a quadratic auto-regressive model, the quadratic auto-regression is performed to the energy gradient curve around the arrival time to pick up the accurate arrival times of P-wave and S-wave. 10 groups of Lushan seismic waves and 150 groups of Wenchuan seismic waves were analyzed. By reference to the manual method, this new method has higher accuracy and stability. Compared with the STA/LTA method and AIC method, this new method is a little less in computing efficiency, but has higher accuracy and reliability in picking up the arrival time of S-wave. This new method has enriched the methods of picking up the arrival times of seismic waves automatically.