特定震源台站校正定位方法及在安徽霍山地区的应用
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摘要
本文详细介绍一种地震定位方法——特定震源台站校正定位法(Source-Specific Station Term,SSST),并应用该方法对安徽大别山的霍山地区1 976～2008年发生的地震进行重新定位研究.重新定位后,原震源位置的精度得以大大提高、空间上分布也更加紧凑.使用bootstrap法对定位偏差进行估计,得到E W、N-S、U-D三个方向的定位误差分别为0.4 km、0.6 km、0.9 km;定位均方根残差得以很大程度上减小,其均值由定位前的1.34 s下降到定位后的0.11 s.文中比较了特定震源台站校正方法与双差方法,结果表明,相对于双差方法,特定震源台站校正法定位条件容易满足,定位后缺失地震较少且还具有一定的绝对定位作用.应用特定震源台站校正方法的结果对霍山区域的地震活动性进行分析,发现重定位后显示出3条明显的密集条带,由此划分出3个密集区并分析其时空分布特征,结果显示这3个密集区在深度上分布都具有较浅的特征,但随时间分布却有所差异.条件允许时,将来可以结合波形互相关技术进一步提高定位精度.
The article mainly introduces an earthquake location method—Source-Specific Station Term (SSST) approach,and presents the application of this method to relocate earthquakes between 1976 and 2008 in the Huoshan area,located in Dabie Mountain in Anhui province.After relocation,the location accuracy is significantly improved and the epicenter distribution is more compact.The location errors,estimated by using a bootstrap approach,are 0.4 km,0.6 km, and 0.9 km in the east-west,north-south,and vertical directions,respectively.The root-mean-squares (RMS) of arrival time residuals have a sharp reduction after the SSST relocation from 1.34 to 0.11 s.We also make a concise comparison between the SSST method and the Double-Difference (DD) algorithm.The result shows that the SSST method can easily be used,and can almost relocate all the events.In addition,it also has achieved some improvements in absolute location.After the SSST relocation,we apply the results to seismicity analysis in the Huoshan area,there are three obvious compact stripes and we divide them into three seismic density zones. Based on the analysis of temporal-spatial distribution characteristics,we find that the three zones all have shallow focal depths,although the temporal-distributions are different.To further improve the location accuracy,the waveform cross-correlation could be combined with the SSST method when conditions permit in the future.
The article mainly introduces an earthquake location method—Source-Specific Station Term (SSST) approach,and presents the application of this method to relocate earthquakes between 1976 and 2008 in the Huoshan area,located in Dabie Mountain in Anhui province.After relocation,the location accuracy is significantly improved and the epicenter distribution is more compact.The location errors,estimated by using a bootstrap approach,are 0.4 km,0.6 km, and 0.9 km in the east-west,north-south,and vertical directions,respectively.The root-mean-squares (RMS) of arrival time residuals have a sharp reduction after the SSST relocation from 1.34 to 0.11 s.We also make a concise comparison between the SSST method and the Double-Difference (DD) algorithm.The result shows that the SSST method can easily be used,and can almost relocate all the events.In addition,it also has achieved some improvements in absolute location.After the SSST relocation,we apply the results to seismicity analysis in the Huoshan area,there are three obvious compact stripes and we divide them into three seismic density zones. Based on the analysis of temporal-spatial distribution characteristics,we find that the three zones all have shallow focal depths,although the temporal-distributions are different.To further improve the location accuracy,the waveform cross-correlation could be combined with the SSST method when conditions permit in the future.
引文
[1] 黄媛.结合波形互相关技术的双差算法在地震定位中的应用探讨.国际地震动态,2008,4:29～34 Huang Y.Study on the application and development of the DD algorithm with cross correlation of waveform data in the earthquake location.Recent Developments in World Seismology (in Chinese),2008,4:29～34
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[10] 郑钰,杨建思.双差算法的剖析及参数对定位的影响.地震地磁观测与研究,2008,29(3) :85～93 Zheng Y,Yang J S.Analysis of double-difference algorithm and the affect of its parameter in location.Seismological and Geomagnetic Observation and Research (in Chinese),2008,29(3) :85～93
[11] Lin G,Shearer P.Tests of relative earthquake location techniques using synthetic data.J.Geophys.Res.,2005,110(B04304) ,doi:10． 1029/2004JB003380
[12] Lin G,Shearer P M,Hauksson E.Applying a threedimensional velocity model,waveform cross correlation,and cluster analysis to locate southern California seismicity from 1981 to2005． J.Geophys.Res.,2007,112(B12309) ,doi:10． 1029/2007JB004986
[13] 赵金花,李波,陆汗鹏等.单一地震事件与多个地震事件的定位方法及应用.地震地磁观测与研究,2007,28(4) :15～19 Zhao J H,Li B,Lu H P,et al.The earthquake location methods for single seismic event and a number of seismic events and their application.Seismological and Geomagnetic Observation and Research (in Chinese),2007,28(4) :15～19
[14] 田玥,陈晓非.地震定位研究综述.地球物理学进展,2002,17(1) :147～155 Tian Y,Chen X F.Review of seismic location study.Progress in Geophysics (in Chinese),2002,17(1) :147～155
[15] 王椿镛,王溪莉,颜其中.昆明地震台网多事件定位问题的初步研究.地震学报,1993,15(2) :136～145 Wang C Y,Wang X L,Yan Q Z.Preliminary study of multiple events to Kunming seismic network.Acta Seismologica Sinica (in Chinese),1993,15(2) :136～145
[16] Shearer P M.Improving local earthquake locations using the L1 norm and waveform cross correlation:application to the Whittier Narrows,California,aftershock sequence.J.Geophys.Res.,1997,102(B4) :8269～8283
[17] Pavlis G,Hokanson N.Separated earthquake location.J.Geophys.Res.,1985,90:12777～12789
[18] Lin G,Shearer P.The COMPLOC earthquake location package.Seismological Research Letters,2006,77(4) :440～444
[19] 马秀芳.用相对定位法测定1973年安徽霍山震群的震源位置.地震研究,1982,5(1) :99～113 Ma X F.Locating the epicenters of the 1973 Huoshan swarm,Anhui province,by the relative locating method.Journal of Seismological Research (in Chinese),1982,5(1) :99～113
[20] 王椿镛,张先康,丁志峰等.大别山造山带上部地壳结构的有限差分层析成像.地球物理学报,1997,40(4) :495～502 Wang C Y,Zhang X K,Ding Z F,et al.Finite-difference tomography of upper crustal structure in Dabieshan orogenic belt.Chinese J.Geophys.(in Chinese),1997,40(4) :495～502
[21] Wang C Y,Zeng R S.A crustal model of the ultrahighpressure Dabie Shan orogenic belt,China,derived from deep seismic refraction profiling.J.Geophys.Res.,2000,105(B5) :10857～10869
[22] 董树文,吴宣志,高锐等.大别造山带地壳速度结构与动力 学.地球物理学报,1998,41(3) :349～361 Dong S W,Wu X Z,Gao R,et al.On the crust velocity levels and dynamics of the Dabieshan orogenic belt.Chinese J.Geophys.(in Chinese),1998,41(3) :349～361
[23] Efron B,Gong G.A leisurely look at the bootstrap,the jackknife,and cross-validation.Am.Stat.,1983,37 (1) :36～48
[24] Efron B,Tibshirani R.Statistical data analysis in the computer age.Science,1994,253(5018) :390～395
[25] 张天中,武巴特尔,黄嫒等.近台资料对近震相对定位算法的影响.地球物理学报,2007,50(4) :1123～1130 ZhangTZ,Wu B T E,Huang Y,et al.Effect of the data recorded at nearby stations on earthquake relative location.ChineseJ.Geophys.(in Chinese),2007,50(4) :1123～1130
[26] 姚大全,张杰,沈小七.安徽霍山地区断层活动习性研究的新进展.地球物理学进展,2006,21(3) :776～782 Yao D Q,Zhang J,Shen X Q.New advance of fault active behavior research in Huoshan area,Anhui province.Progress in Geophysics (in Chinese),2006,21 (3) :776～782
[2] Schaff D P,Richards P G.Lg-wave cross correlation and double-difference location:application to the 1999 Xiuyan,China,sequence.Bull.Seism.Soc.Am.,2004,94(3) :867～879
[3] Richards-Dinger K B,Shearer P M.Earthquake locations in southern California obtained using source-specific station terms.J.Geophys.Res.,2000,105(B5) :10939～10960
[4] Waldhauser F,Ellsworth W.A double-difference earthquake location algorithm:method and application to the northern Hayward fault,California.Bull.Seism.Soc.Am.,2000,90(6) :1353～1368
[5] 杨智娴,陈运泰,郑月军等.双差地震定位法在我国中西部地区地震精确定位中的应用.中国科学(D辑),2003,33(增刊):129～134 Yang Z X,Chen Y T,Zheng Y J,et al.Accurate relocation of earthquakes in central-western China using the double difference earthquake location algorithm.Science in China(SeriesD) (in Chinese),2003,33(Suppl.):129～134
[6] 朱艾斓,徐锡伟,周永胜等.川西地区小震重新定位及其活动构造意义.地球物理学报,2005,48(3) :629～636 Zhu A L,Xu X W,Zhou Y S,et al.Relocation of small earthquakes in western Sichuan,China and its implications for active tectonics.Chinese J.Geophys.(in Chinese),2005,48(3) :629～636
[7] Hauksson E,Shearer P.Southern California hypocenter relocation with waveform cross-correlation,Part 1:Results using the double difference method.Bull.Seism.Soc.Am.,2005,95(3) :896～903
[8] 黄耘,李清河,张元生等.江苏及邻区地震重新定位和构造特征分析.地球物理学报,2008,51(1) :175～185 Huang Y,Li Q H,Zhang Y S,et al.Relocation of earthquakes in Jiangsu and neighboring areas,China and analysis of structural features.Chinese J.Geophys.(in Chinese),2008,51(1) :175～185
[9] 黄媛,吴建平,张天中等.汶川8． 0级大地震及其余震序列重定位研究.中国科学(D辑),2008,38(10) :1242～1249 Huang Y,Wu J P,Zhang T Z,et al.Research of relocation for aftershock sequences of Wenchuan strong earthquake.Science in China (Series D) (in Chinese),2008,38(10) :1242～1249
[10] 郑钰,杨建思.双差算法的剖析及参数对定位的影响.地震地磁观测与研究,2008,29(3) :85～93 Zheng Y,Yang J S.Analysis of double-difference algorithm and the affect of its parameter in location.Seismological and Geomagnetic Observation and Research (in Chinese),2008,29(3) :85～93
[11] Lin G,Shearer P.Tests of relative earthquake location techniques using synthetic data.J.Geophys.Res.,2005,110(B04304) ,doi:10． 1029/2004JB003380
[12] Lin G,Shearer P M,Hauksson E.Applying a threedimensional velocity model,waveform cross correlation,and cluster analysis to locate southern California seismicity from 1981 to2005． J.Geophys.Res.,2007,112(B12309) ,doi:10． 1029/2007JB004986
[13] 赵金花,李波,陆汗鹏等.单一地震事件与多个地震事件的定位方法及应用.地震地磁观测与研究,2007,28(4) :15～19 Zhao J H,Li B,Lu H P,et al.The earthquake location methods for single seismic event and a number of seismic events and their application.Seismological and Geomagnetic Observation and Research (in Chinese),2007,28(4) :15～19
[14] 田玥,陈晓非.地震定位研究综述.地球物理学进展,2002,17(1) :147～155 Tian Y,Chen X F.Review of seismic location study.Progress in Geophysics (in Chinese),2002,17(1) :147～155
[15] 王椿镛,王溪莉,颜其中.昆明地震台网多事件定位问题的初步研究.地震学报,1993,15(2) :136～145 Wang C Y,Wang X L,Yan Q Z.Preliminary study of multiple events to Kunming seismic network.Acta Seismologica Sinica (in Chinese),1993,15(2) :136～145
[16] Shearer P M.Improving local earthquake locations using the L1 norm and waveform cross correlation:application to the Whittier Narrows,California,aftershock sequence.J.Geophys.Res.,1997,102(B4) :8269～8283
[17] Pavlis G,Hokanson N.Separated earthquake location.J.Geophys.Res.,1985,90:12777～12789
[18] Lin G,Shearer P.The COMPLOC earthquake location package.Seismological Research Letters,2006,77(4) :440～444
[19] 马秀芳.用相对定位法测定1973年安徽霍山震群的震源位置.地震研究,1982,5(1) :99～113 Ma X F.Locating the epicenters of the 1973 Huoshan swarm,Anhui province,by the relative locating method.Journal of Seismological Research (in Chinese),1982,5(1) :99～113
[20] 王椿镛,张先康,丁志峰等.大别山造山带上部地壳结构的有限差分层析成像.地球物理学报,1997,40(4) :495～502 Wang C Y,Zhang X K,Ding Z F,et al.Finite-difference tomography of upper crustal structure in Dabieshan orogenic belt.Chinese J.Geophys.(in Chinese),1997,40(4) :495～502
[21] Wang C Y,Zeng R S.A crustal model of the ultrahighpressure Dabie Shan orogenic belt,China,derived from deep seismic refraction profiling.J.Geophys.Res.,2000,105(B5) :10857～10869
[22] 董树文,吴宣志,高锐等.大别造山带地壳速度结构与动力 学.地球物理学报,1998,41(3) :349～361 Dong S W,Wu X Z,Gao R,et al.On the crust velocity levels and dynamics of the Dabieshan orogenic belt.Chinese J.Geophys.(in Chinese),1998,41(3) :349～361
[23] Efron B,Gong G.A leisurely look at the bootstrap,the jackknife,and cross-validation.Am.Stat.,1983,37 (1) :36～48
[24] Efron B,Tibshirani R.Statistical data analysis in the computer age.Science,1994,253(5018) :390～395
[25] 张天中,武巴特尔,黄嫒等.近台资料对近震相对定位算法的影响.地球物理学报,2007,50(4) :1123～1130 ZhangTZ,Wu B T E,Huang Y,et al.Effect of the data recorded at nearby stations on earthquake relative location.ChineseJ.Geophys.(in Chinese),2007,50(4) :1123～1130
[26] 姚大全,张杰,沈小七.安徽霍山地区断层活动习性研究的新进展.地球物理学进展,2006,21(3) :776～782 Yao D Q,Zhang J,Shen X Q.New advance of fault active behavior research in Huoshan area,Anhui province.Progress in Geophysics (in Chinese),2006,21 (3) :776～782
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