一种自动扫描地震漏检事件方法的研究与实现
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摘要
地震事件的自动处理过程中会发生遗漏。台站数量越多,地震分析员在手动扫描遗漏事件时所花费的时间就越长。本文讨论了一种自动扫描漏检事件的方法,该方法利用分析员的分析经验,结合台站分布状况和地球物理学规则,重新关联那些具有很可能来自特定震源区域而未被分析员关联的信号,以形成一个待验证的事件,供分析员审定。该方法大大减少了分析员的工作量,提高了地震公报的质量。
There are more than eight thousands times more than magnitude four in the world ever years.The seismic waves excited by two or more different earthquakes sometimes at the same time reach the observation seismic stations;it is difficult for seismic analysts to manually look for missed seismic events by the automated process software without any tools.The analysts have to spend more time to scan missed event in manual when there are more and more the number of stations in the network.The experience of the analysts determines whether to effectively detect the missed events and experienced analysts can successfully detect missed seismic events by the automated process system in a relatively short period of time.How to reduce the workload of analysts,as well as how to improve the efficiency and accuracy of their work is the issue which we discuss in the paper. The method of scanning the missed seismic events automatically and the software developed base on the method are introduced in the paper.Automatic scanning missed event method can scan the unassociated signal in the automatic process phase and re-associate them to form a new event.It captures the knowledge of experienced analysts and makes that knowledge available to all analyst and uses empirically derived information to identify candidate association sets for a given source region.We divide the world into several geographic focal regions according to the geographical distribution of seismic stations in NDC monitoring system and the earth physics rules.There is a corresponding set of sensitive stations in each certain region.The criteria for the source regions and candidate arrivals are defined in the NDC database tables and user definable options to control processing are stored in a parameter file.Each region is given a name,region identifier(number),and upper and lower bounds for latitude and longitude.The scanning software computes an initial P travel-time window for each station to the closest and furthest point in the region. To sum up,the scanning software can scan automatically unassociated seismic signals to form region specific events,according to the slowness and azimuth of signals,and then reduce the number of missed events.The signal to noise ratio,period and amplitude are also considered in the design of software,but tuning these three parameters need long-term statistical analysis,these parameters are not configured in our trial operation stage.In the future,these parameters can be added to the scanning software,no need to modify the program. The scanning software is developed on the platform of Solaris system and Oracle database,the core codes are programmed using standard C language.The software has been integrated into the national data center interaction analysis software and has obtained the good effect in the stage of trail operation.It greatly reduces the workload of analyst and improves the seismic bulletin.The change of seismic stations can influence the efficiency of the scanning software,so,the operations parameters need timely be adjusted according to the change of the monitoring station and monitoring network in order to improve the accuracy of the scanning software.
There are more than eight thousands times more than magnitude four in the world ever years.The seismic waves excited by two or more different earthquakes sometimes at the same time reach the observation seismic stations;it is difficult for seismic analysts to manually look for missed seismic events by the automated process software without any tools.The analysts have to spend more time to scan missed event in manual when there are more and more the number of stations in the network.The experience of the analysts determines whether to effectively detect the missed events and experienced analysts can successfully detect missed seismic events by the automated process system in a relatively short period of time.How to reduce the workload of analysts,as well as how to improve the efficiency and accuracy of their work is the issue which we discuss in the paper. The method of scanning the missed seismic events automatically and the software developed base on the method are introduced in the paper.Automatic scanning missed event method can scan the unassociated signal in the automatic process phase and re-associate them to form a new event.It captures the knowledge of experienced analysts and makes that knowledge available to all analyst and uses empirically derived information to identify candidate association sets for a given source region.We divide the world into several geographic focal regions according to the geographical distribution of seismic stations in NDC monitoring system and the earth physics rules.There is a corresponding set of sensitive stations in each certain region.The criteria for the source regions and candidate arrivals are defined in the NDC database tables and user definable options to control processing are stored in a parameter file.Each region is given a name,region identifier(number),and upper and lower bounds for latitude and longitude.The scanning software computes an initial P travel-time window for each station to the closest and furthest point in the region. To sum up,the scanning software can scan automatically unassociated seismic signals to form region specific events,according to the slowness and azimuth of signals,and then reduce the number of missed events.The signal to noise ratio,period and amplitude are also considered in the design of software,but tuning these three parameters need long-term statistical analysis,these parameters are not configured in our trial operation stage.In the future,these parameters can be added to the scanning software,no need to modify the program. The scanning software is developed on the platform of Solaris system and Oracle database,the core codes are programmed using standard C language.The software has been integrated into the national data center interaction analysis software and has obtained the good effect in the stage of trail operation.It greatly reduces the workload of analyst and improves the seismic bulletin.The change of seismic stations can influence the efficiency of the scanning software,so,the operations parameters need timely be adjusted according to the change of the monitoring station and monitoring network in order to improve the accuracy of the scanning software.
引文
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[3]周彦文,刘希强.地震事件自动检测新方法[J].西北地震学报,2008,30(2):102-106.ZHOU Yan-wen,LIU Xi-qiang.A New Method of AutomaticSeism in Event Detection[J].Northwestern SeismologicalJournal,2008,30(2):102-106.
[4]傅淑芳,刘宝诚.地震学教程[M].北京:地震出版社,1991:410-411.FU Shu-fang,LIU Bao-cheng.Seismology Yutorial[M].Bei-jing:Earthquake Press,1991:410-411.
[5]王娟,张波,邱宏茂.兰州和海拉尔核查地震台阵慢度和方位角校正方法研究[J].西北地震学报,2010,32(3):330-334.WANGg Juan,ZHAO Bo,QIU Hong-mao.Research onMethod of Slowness-Azimuth Station Corrections for LZDMand HILR Verification Seismic Arrays[J].Northwestern Seis-mological Journal,2010,35(4):330-334.
[6]Urman S.Oracle8 PL/SQL Programming[M].[S.l.]:McGraw-Hill Companies,1997:26-28.
[7]Rich Teer.Solaris系统编程[M].北京:机械工业出版社,2004:35-37.Rich Teer.Solaris System Programming[M].Beijing:Ma-chinery Industry Press,2004:35-37.
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