用振幅变化长短时均值比实现地震预警中P波自动拾取
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摘要
地震P波到时快速、精确的自动拾取是实现地震预警的第一步。目前所有P波到时自动拾取方法都需要进一步考虑准确度问题,据此提出用"振幅变化"长短时均值比方法拾取P波到时。研究表明引进"振幅变化"作为特征函数比Allen的"振幅变化平方"更能突显地震波初至时刻的"突变"特征。对"振幅变化长短时均值比方法"和Allen的"振幅变化平方长短时均值比方法"进行抗噪音分析表明,在较低信噪比条件下,Allen方法不能准确地拾取P波到时,而新方法依然能较准确地拾取P波到时。在较高信噪比条件下,用两种方法拾取的160个M_S>4.0地震P波到时,其误差大都在允许范围内,但新方法拾取的准确度略高。新方法可以看做是对长短时均值比方法的拓展。
The first step to realize earthquake early warning is to pick P-wave arrival time quickly, accurately, and automatically. In the current automatic methods of picking up P-wave arrival time, the anti-interference ability needs to be encountered; thus, in this study, the short-term average/long-term average(STA/LTA) method for detecting amplitude changes is proposed for picking up P-wave arrival times. The study shows that compared with the Allen algorithm, the amplitude change can be used as the characteristic function to highlight the mutation feature of seismic wave arrival time. Moreover, using the STA/LTA method, the pick-up deviation of seismic wave arrival times caused by the interference can be reduced. Analyses of anti-interference in the STA/LTA method and Allen algorithm show that in the presence of a large amplitude interference, the Allen algorithm cannot pick up P-wave arrival times because the peak value does not appear in the P-wave first arrival position; however, the anomaly in the P-wave arrival time position is still obvious when using the proposed method. Under less amplitude disturbance, the two methods are used to pick up the P-wave arrival time of 160 M_S≥4.0 earthquakes, and the accuracy of the new method is slightly higher. The new method can be seen as an extension of the STA/LTA transform method.
The first step to realize earthquake early warning is to pick P-wave arrival time quickly, accurately, and automatically. In the current automatic methods of picking up P-wave arrival time, the anti-interference ability needs to be encountered; thus, in this study, the short-term average/long-term average(STA/LTA) method for detecting amplitude changes is proposed for picking up P-wave arrival times. The study shows that compared with the Allen algorithm, the amplitude change can be used as the characteristic function to highlight the mutation feature of seismic wave arrival time. Moreover, using the STA/LTA method, the pick-up deviation of seismic wave arrival times caused by the interference can be reduced. Analyses of anti-interference in the STA/LTA method and Allen algorithm show that in the presence of a large amplitude interference, the Allen algorithm cannot pick up P-wave arrival times because the peak value does not appear in the P-wave first arrival position; however, the anomaly in the P-wave arrival time position is still obvious when using the proposed method. Under less amplitude disturbance, the two methods are used to pick up the P-wave arrival time of 160 M_S≥4.0 earthquakes, and the accuracy of the new method is slightly higher. The new method can be seen as an extension of the STA/LTA transform method.
引文
[1] ALLEN R V.Automatic Earthquake Recognition and Timing from Single Traces[J].BSSA,1978,68(5):1521-1532.
[2] ALLEN R V.Automatic Phasepickers:Their Present Use and Future Prospects[J].BSSA,1982,72(6B):225-242.
[3] JONES J P,VAN der Baan M.Adaptive STA-LTA with Outlier Statistics[J].BSSA,2015,105(3):1606-1618.
[4] 田优平,赵爱华.基于小波包和峰度赤池信息量准则的P波震相自动识别方法[J].地震学报,2016,38(1):71-85.TIAN Youping,ZHAO Aihua.Automatic Identification of P-phase Based on Wavelet Packet and Kurtosis-AIC Method[J].Acta Seismologica sinica,2016,38(1):71-85.
[5] 何先龙,佘天莉,高峰.一种地震P波和S波初至时间自动拾取的新方法[J].地球物理学报,2016,59(7):2519-2527.HE Xianlong,SHE Tianli,GAO Feng.A New Method for Picking up Arrival Times of Seismic P and S Waves Automatically[J].Chinese Journal of Geophys,2016,59(7):2519-2527.
[6] Akaike.Information Theory and an Extension of the Maximum Likelihood Principle[C]//2nd International Symposium on Information Theory.Budapest:Akademiai Kiado,1973:267-281.
[7] MAEDA N.A Method for Reading and Checking Phase Time in Auto-processing System of Seismic Wavedata[J].Zisin-J1sin,1985,38(3):365-379.
[8] 王继,陈九辉,刘启元,等.流动地震台阵观测初至震相的自动检测[J].地震学报,2006,28(1):42-51.WANG Ji,CHEN Jiuhui,LIU Qiyuan,et al.Automatic Onset Phase Picking for Portable Seismic Arry Observation[J].ACTA Seismologica Sinica,2006,28(1):42-51.
[9] SARAGIOTIS C D.PAI-S/K:A Robust Automatic Seismic P Phase Arrival Identification Scheme[J].IEEE Transactions on Geoscience and Remote Sensing,2002,40(60):1395-1404.
[10] 刘劲松,王赟,姚振兴,等.微地震信号到时自动拾取方法[J].地球物理学报,2013,56(5):1660-1666.LIU Jinsong,WANG Yun,YAO Zhenxing,et al.On Micro-seismic First Arrival Identification:A Case Study[J].Chinese Journal of Geophysics,2013,56(5):1660-1666.
[11] REINOUD Sleeman,TORILD Van Eck.Robust Automatic P-phase Picking:An On-line Implementation in the Analysis of Broad-band Seismogram Recording[J].Phys Earth Planet Inter,1999,113(1-4):265-275.
[12] KANAMORI H.Real-ime Seismology and Earthquake Damage Mitigation[J].Annual Review of Earth and Planetary Sciences,2005,33:195-214.
[2] ALLEN R V.Automatic Phasepickers:Their Present Use and Future Prospects[J].BSSA,1982,72(6B):225-242.
[3] JONES J P,VAN der Baan M.Adaptive STA-LTA with Outlier Statistics[J].BSSA,2015,105(3):1606-1618.
[4] 田优平,赵爱华.基于小波包和峰度赤池信息量准则的P波震相自动识别方法[J].地震学报,2016,38(1):71-85.TIAN Youping,ZHAO Aihua.Automatic Identification of P-phase Based on Wavelet Packet and Kurtosis-AIC Method[J].Acta Seismologica sinica,2016,38(1):71-85.
[5] 何先龙,佘天莉,高峰.一种地震P波和S波初至时间自动拾取的新方法[J].地球物理学报,2016,59(7):2519-2527.HE Xianlong,SHE Tianli,GAO Feng.A New Method for Picking up Arrival Times of Seismic P and S Waves Automatically[J].Chinese Journal of Geophys,2016,59(7):2519-2527.
[6] Akaike.Information Theory and an Extension of the Maximum Likelihood Principle[C]//2nd International Symposium on Information Theory.Budapest:Akademiai Kiado,1973:267-281.
[7] MAEDA N.A Method for Reading and Checking Phase Time in Auto-processing System of Seismic Wavedata[J].Zisin-J1sin,1985,38(3):365-379.
[8] 王继,陈九辉,刘启元,等.流动地震台阵观测初至震相的自动检测[J].地震学报,2006,28(1):42-51.WANG Ji,CHEN Jiuhui,LIU Qiyuan,et al.Automatic Onset Phase Picking for Portable Seismic Arry Observation[J].ACTA Seismologica Sinica,2006,28(1):42-51.
[9] SARAGIOTIS C D.PAI-S/K:A Robust Automatic Seismic P Phase Arrival Identification Scheme[J].IEEE Transactions on Geoscience and Remote Sensing,2002,40(60):1395-1404.
[10] 刘劲松,王赟,姚振兴,等.微地震信号到时自动拾取方法[J].地球物理学报,2013,56(5):1660-1666.LIU Jinsong,WANG Yun,YAO Zhenxing,et al.On Micro-seismic First Arrival Identification:A Case Study[J].Chinese Journal of Geophysics,2013,56(5):1660-1666.
[11] REINOUD Sleeman,TORILD Van Eck.Robust Automatic P-phase Picking:An On-line Implementation in the Analysis of Broad-band Seismogram Recording[J].Phys Earth Planet Inter,1999,113(1-4):265-275.
[12] KANAMORI H.Real-ime Seismology and Earthquake Damage Mitigation[J].Annual Review of Earth and Planetary Sciences,2005,33:195-214.