多地震活动性参数在断裂带现今活动习性与地震危险性评价中的应用与问题
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摘要
为了分析将地震活动性参数用于判定断裂带现今活动习性、进而评估长期地震危险性的可行性,文中介绍了沿断裂带进行b值扫描与填图的方法,以及进行断裂带分段的多参数值(—b、E、n和—a/—b)组合分析的资料处理、计算及分析步骤;提出了为进行多参数计算的、断裂带分段的参考判据,进而概括了根据计算的参数值、结合强震历史背景、现今地震分布综合分析断裂带现今活动习性空间差异的方法与思路。以5条地震活动水平和监测能力各异的断裂带为试验对象,基于归纳的方法综合分析了各断裂带现今活动习性的空间差异及潜在的地震危险段。文中还就断裂的震后调整运动与低b值的关系以及精定位的地震资料在参数计算中的合理使用等问题进行了讨论。主要认识为:以b值为主的若干地震活动性参数的空间分布可有效地用于断裂带现今活动习性及潜在强震危险段落的判定。沿断裂带b值扫描与填图以及断裂带分段多参数值组合分析两种方法,可分别应用于地震监测能力强和一般的地区;若在监测能力强的地区将两种方法结合起来使用,可获得更可靠的结果。晚期余震活跃或者大震后调整运动的断裂段也可表现出较低b或—b值的特点。
In order to analyze the feasibility using seismicity parameters to identify current faulting behavior and hence to assess long-term seismic potential of active fault zones,we introduced the technique of spatially scanning and mapping b values along fault zones,as well as the procedure of data processing,calculating and result analyzing of multiple-seismicity-parameter-value combinations(i.e.b—,E,n and a—/b—)for various fault-segments in this paper.We then brought forward several reference criterions for fault segmentation,that is,the calculation of multiple seismicity parameters.Moreover,we generalized the approach and thinking of synthetically identifying spatial differences of current faulting behavior from the calculated parameters by combining histories of strong and major earthquakes and spatial distributions of modern seismicity.As an application,we took 5 active fault zones with various current seismicity levels and seismic detectabilities as the experimental targets to analyze synthetically the spatial differences of current faulting behaviors and identify fault segments with potential risk of strong earthquakes for each of the 5 fault zones basing on the generalized approach or methods.Meanwhile,the issues,such as the relation between the postseismic fault healing and relatively low b-value,the proper use of high-accurate re-located seismic data in the parameter calculating,and etc.have also been discussed.The results mainly suggest that the spatial distribution of multiple seismicity parameter values,among which the b-value is the most important one,can be effectively applied to analyzing current faulting behaviors and hence to identifying fault segments with potential risk of strong or major earthquakes.The two methods,the scanning and mapping of b-values along fault zones and the analysis of multi-parameter-value combinations for various fault-segments,can be applied to active fault zones in areas of high or moderate seismic detectability,respectively.And if the two methods are employed to areas with higher seismic detectability,more reliable results will be obtained.Fault-segments with activity of late-stage aftershocks or with postseismic fault healing may have relatively low b or b—-values too.We believe that once a catalog of earthquakes accurately relocated is used in calculation of seismicity parameters,it must contain the complete data of earthquakes occurring during the period and in the area studied,rather than only a part of data selected.
In order to analyze the feasibility using seismicity parameters to identify current faulting behavior and hence to assess long-term seismic potential of active fault zones,we introduced the technique of spatially scanning and mapping b values along fault zones,as well as the procedure of data processing,calculating and result analyzing of multiple-seismicity-parameter-value combinations(i.e.b—,E,n and a—/b—)for various fault-segments in this paper.We then brought forward several reference criterions for fault segmentation,that is,the calculation of multiple seismicity parameters.Moreover,we generalized the approach and thinking of synthetically identifying spatial differences of current faulting behavior from the calculated parameters by combining histories of strong and major earthquakes and spatial distributions of modern seismicity.As an application,we took 5 active fault zones with various current seismicity levels and seismic detectabilities as the experimental targets to analyze synthetically the spatial differences of current faulting behaviors and identify fault segments with potential risk of strong earthquakes for each of the 5 fault zones basing on the generalized approach or methods.Meanwhile,the issues,such as the relation between the postseismic fault healing and relatively low b-value,the proper use of high-accurate re-located seismic data in the parameter calculating,and etc.have also been discussed.The results mainly suggest that the spatial distribution of multiple seismicity parameter values,among which the b-value is the most important one,can be effectively applied to analyzing current faulting behaviors and hence to identifying fault segments with potential risk of strong or major earthquakes.The two methods,the scanning and mapping of b-values along fault zones and the analysis of multi-parameter-value combinations for various fault-segments,can be applied to active fault zones in areas of high or moderate seismic detectability,respectively.And if the two methods are employed to areas with higher seismic detectability,more reliable results will be obtained.Fault-segments with activity of late-stage aftershocks or with postseismic fault healing may have relatively low b or b—-values too.We believe that once a catalog of earthquakes accurately relocated is used in calculation of seismicity parameters,it must contain the complete data of earthquakes occurring during the period and in the area studied,rather than only a part of data selected.
引文
国家地震局地球物理研究所,复旦大学历史地理研究所.1990a.中国历史地震图集(远古至元时期)[Z].北京:中国地图出版社.1—174.Institute of Geophysics of Sate Seismological Bureau and Institute of Historic Geography of Fudan University.1990a.The Atlas of Historic Earthquakes of China(Volumes for Remote Antiquity to Yuan Dynasties)[Z].China Car-tographic Publishing House,Beijing.1—174(in Chinese).
国家地震局地球物理研究所,复旦大学历史地理研究所.1990b.中国历史地震图集(明时期)[Z].北京:中国地图出版社.1—194.Institute of Geophysics of Sate Seismological Bureau and Institute of Historic Geography of Fudan University.1990b.The Atlas of Historic Earthquakes of China(Volumes for Ming Dynasty)[Z].China Cartographic PublishingHouse,Beijing.1—194(in Chinese).
国家地震局地球物理研究所,复旦大学历史地理研究所.1990c.中国历史地震图集(清时期)[Z].北京:中国地图出版社.1—244.Institute of Geophysics of Sate Seismological Bureau and Institute of Historic Geography of Fudan University.1990c.The Atlas of Historic Earthquakes of China(Volumes for Ding Dynasty)[Z].China Cartographic PublishingHouse,Beijing.1—244(in Chinese).
国家地震局震害防御司.1995.中国历史强震目录[Z].北京:地震出版社.1—514.Department of Earthquake Disaster Prevention,State Seismological Bureau.1995.The Catalogue of Chinese HistoricalStrong Earthquakes[Z].Seismological Press,Beijing.1—514(in Chinese).
闻学泽.2000.四川西部鲜水河?安宁河?则木河断裂带的地震破裂分段特征[J].地震地质,22(3):239—249.WEN Xue-ze.2000.Character of rupture segmentation of the Xianshuihe-Anninghe-Zemuhe Fault zone,western Si-chuan[J].Seismology and Geology,22(3):239—249(in Chinese).
闻学泽.2001.活动断裂的可变破裂尺度地震行为与级联破裂模式的应用[J].地震学报,23(4):380—390.WEN Xue-ze.2001.Earthquake behavior of variable rupture-scale on active faults and application of the cascade-rup-turing model[J].Acta Seismologica Sinica,14(4):404—416.
闻学泽,徐锡伟.2005.对东南沿海1067年和1574年两次地震的分析[J].地震地质,27(1):1—10.WEN Xue-ze,XU Xi-wei.2005.Analysis of the two historical earthquakes of1067and1574in the southeast coastalregion of China[J].Seismology and Geology,27(1):1—10(in Chinese).
徐锡伟,邓起东.1993.1303年洪洞地震的地震构造[A].见:马宗晋主编.山西临汾地震研究与系统减灾.北京:地震出版社.149—158.XU Xi-wei,DENG Qi-dong.1993.Seismotectonics of the1303Hongdong earthquake[A].In:MA Zong-jin(ed).Studies of the Linfen Earthquake,Shanxi and the Systematic Disaster Reducing.Seismological Press,Beijing.149—158(in Chinese).
易桂喜,闻学泽,范军,等.2004a.由地震活动参数分析安宁河?则木河断裂带的现今活动习性及地震危险性[J].地震学报,26(3):294—303.YI Gui-xi,WEN Xue-ze,FAN Jun,et al.2004a.Assessing current faulting behaviors and seismic risk of the Anning-he-Zemuhe Fault zone from seismicity parameters[J].Acta Seismologica Sinica,17(3):322—333.
易桂喜,闻学泽,徐锡伟.2004b.山西断陷带太原-临汾部分的强地震平均复发间隔与未来危险段落研究[J].地震学报,26(4):387—395.YI Gui-xi,WEN Xue-ze,XU Xi-wei.2004b.Average recurrence intervals of strong earthquakes and potential riskysegments along the Taiyuan-Linfen portion of the Shanxi graben system[J].Acta Seismologica Sinica,17(4):426—437.
易桂喜,范军,闻学泽.2005.由现今地震活动分析鲜水河断裂带中?南段活动习性与强震危险地段[J].地震,25(1):58—66.YI Gui-xi,FAN Jun,WEN Xue-ze.2005.Study on faulting behavior and fault-segments for potential strong earth-quake risk along the central-southern segment of Xianshuihe Fault zone based on current seismicity[J].Earth-quake,25(1):58—66(in Chinese).
易桂喜,闻学泽,王思维,等.2006.由地震活动参数分析龙门山-岷山断裂带的现今活动习性与地震危险性[J].中国地震,22(2):117—125.YI Gui-xi,WEN Xue-ze,WANG Si-wei,et al.2006.Study on faulting behaviors and strong-earthquake risk of theLongmenshan-Minshan Fault zones from current seismicity parameters[J].Earthquake Research in China,22(2):117—125(in Chinese).
中国地震局震害防御司.1999.中国近代地震目录[Z].北京:中国科学技术出版社.1—637.Department of Earthquake Disaster Prevention,China Seismological Bureau.1999.The Catalogue of Modern Earth-quakes of China[Z].Chinese Science and Technology Press,Beijing.1—637(in Chinese).
Aki K.1984.Asperities,barriers,characteristic earthquakes and strong motion prediction[J].J Geophys Res,89(B7):5867—5872.
Allen C R,Lou Z L,Qian H,et al.1991.Field study of a highly active Fault zone:The Xianshuihe fault of south-western China[J].Geol Soc Am Bull,103:1178—1199.
Prugger A F,Gendzwill D J.1988.Microearthquake location:a nonlinear approach that makes use of a simplex step-ping procedure[J].Bull Seism Soc Am,78(2):799—815.
Scholz C H.1968.The frequency-magnitude relation to microfracturing in rock and its relation to earthquakes[J].Bull Seism Soc Am,58:399—415.
Urbancic TI,Trifu C I,Long J M,et al.1992.Space-time correlation ofbvalues with stress release[J].Pure ApplGeophys,139:449—462.
Wells D L,Coppersmith K J.1994.New empirical relationships among magnitude,rupture length,rupture width,rupture area,and surface displacement[J].Bull Seism Soc Am,84:974—1002.
Wiemer S,Wyss M.1997.Mapping the frequency-magnitude distribution in asperities:An improved technique to cal-culate recurrence times?[J].J Geophys Res,102(B7):15115—15128.
Wiemer S,Wyss M.2000.Minimum magnitude of completeness in earthquake catalogs:examples from Alaska,thewestern United States,and Japan[J].Bull Seismol Soc Am,90:859—869.
Wyss M,Schorlemmer D,Wiemer S.2000.Mapping asperities by minima of local recurrence time:San Jacinto-Elsi-nore fault zones[J].J Geophys Res,105(B4):7829—7844.
Wyss M and Matsumura S.2002.Most likely location of large earthquakes in the Kanto and Tokai areas,Japan,basedon the local recurrence times[J].Physics of the Earth and Planetary Interiors,131:173—184.
国家地震局地球物理研究所,复旦大学历史地理研究所.1990b.中国历史地震图集(明时期)[Z].北京:中国地图出版社.1—194.Institute of Geophysics of Sate Seismological Bureau and Institute of Historic Geography of Fudan University.1990b.The Atlas of Historic Earthquakes of China(Volumes for Ming Dynasty)[Z].China Cartographic PublishingHouse,Beijing.1—194(in Chinese).
国家地震局地球物理研究所,复旦大学历史地理研究所.1990c.中国历史地震图集(清时期)[Z].北京:中国地图出版社.1—244.Institute of Geophysics of Sate Seismological Bureau and Institute of Historic Geography of Fudan University.1990c.The Atlas of Historic Earthquakes of China(Volumes for Ding Dynasty)[Z].China Cartographic PublishingHouse,Beijing.1—244(in Chinese).
国家地震局震害防御司.1995.中国历史强震目录[Z].北京:地震出版社.1—514.Department of Earthquake Disaster Prevention,State Seismological Bureau.1995.The Catalogue of Chinese HistoricalStrong Earthquakes[Z].Seismological Press,Beijing.1—514(in Chinese).
闻学泽.2000.四川西部鲜水河?安宁河?则木河断裂带的地震破裂分段特征[J].地震地质,22(3):239—249.WEN Xue-ze.2000.Character of rupture segmentation of the Xianshuihe-Anninghe-Zemuhe Fault zone,western Si-chuan[J].Seismology and Geology,22(3):239—249(in Chinese).
闻学泽.2001.活动断裂的可变破裂尺度地震行为与级联破裂模式的应用[J].地震学报,23(4):380—390.WEN Xue-ze.2001.Earthquake behavior of variable rupture-scale on active faults and application of the cascade-rup-turing model[J].Acta Seismologica Sinica,14(4):404—416.
闻学泽,徐锡伟.2005.对东南沿海1067年和1574年两次地震的分析[J].地震地质,27(1):1—10.WEN Xue-ze,XU Xi-wei.2005.Analysis of the two historical earthquakes of1067and1574in the southeast coastalregion of China[J].Seismology and Geology,27(1):1—10(in Chinese).
徐锡伟,邓起东.1993.1303年洪洞地震的地震构造[A].见:马宗晋主编.山西临汾地震研究与系统减灾.北京:地震出版社.149—158.XU Xi-wei,DENG Qi-dong.1993.Seismotectonics of the1303Hongdong earthquake[A].In:MA Zong-jin(ed).Studies of the Linfen Earthquake,Shanxi and the Systematic Disaster Reducing.Seismological Press,Beijing.149—158(in Chinese).
易桂喜,闻学泽,范军,等.2004a.由地震活动参数分析安宁河?则木河断裂带的现今活动习性及地震危险性[J].地震学报,26(3):294—303.YI Gui-xi,WEN Xue-ze,FAN Jun,et al.2004a.Assessing current faulting behaviors and seismic risk of the Anning-he-Zemuhe Fault zone from seismicity parameters[J].Acta Seismologica Sinica,17(3):322—333.
易桂喜,闻学泽,徐锡伟.2004b.山西断陷带太原-临汾部分的强地震平均复发间隔与未来危险段落研究[J].地震学报,26(4):387—395.YI Gui-xi,WEN Xue-ze,XU Xi-wei.2004b.Average recurrence intervals of strong earthquakes and potential riskysegments along the Taiyuan-Linfen portion of the Shanxi graben system[J].Acta Seismologica Sinica,17(4):426—437.
易桂喜,范军,闻学泽.2005.由现今地震活动分析鲜水河断裂带中?南段活动习性与强震危险地段[J].地震,25(1):58—66.YI Gui-xi,FAN Jun,WEN Xue-ze.2005.Study on faulting behavior and fault-segments for potential strong earth-quake risk along the central-southern segment of Xianshuihe Fault zone based on current seismicity[J].Earth-quake,25(1):58—66(in Chinese).
易桂喜,闻学泽,王思维,等.2006.由地震活动参数分析龙门山-岷山断裂带的现今活动习性与地震危险性[J].中国地震,22(2):117—125.YI Gui-xi,WEN Xue-ze,WANG Si-wei,et al.2006.Study on faulting behaviors and strong-earthquake risk of theLongmenshan-Minshan Fault zones from current seismicity parameters[J].Earthquake Research in China,22(2):117—125(in Chinese).
中国地震局震害防御司.1999.中国近代地震目录[Z].北京:中国科学技术出版社.1—637.Department of Earthquake Disaster Prevention,China Seismological Bureau.1999.The Catalogue of Modern Earth-quakes of China[Z].Chinese Science and Technology Press,Beijing.1—637(in Chinese).
Aki K.1984.Asperities,barriers,characteristic earthquakes and strong motion prediction[J].J Geophys Res,89(B7):5867—5872.
Allen C R,Lou Z L,Qian H,et al.1991.Field study of a highly active Fault zone:The Xianshuihe fault of south-western China[J].Geol Soc Am Bull,103:1178—1199.
Prugger A F,Gendzwill D J.1988.Microearthquake location:a nonlinear approach that makes use of a simplex step-ping procedure[J].Bull Seism Soc Am,78(2):799—815.
Scholz C H.1968.The frequency-magnitude relation to microfracturing in rock and its relation to earthquakes[J].Bull Seism Soc Am,58:399—415.
Urbancic TI,Trifu C I,Long J M,et al.1992.Space-time correlation ofbvalues with stress release[J].Pure ApplGeophys,139:449—462.
Wells D L,Coppersmith K J.1994.New empirical relationships among magnitude,rupture length,rupture width,rupture area,and surface displacement[J].Bull Seism Soc Am,84:974—1002.
Wiemer S,Wyss M.1997.Mapping the frequency-magnitude distribution in asperities:An improved technique to cal-culate recurrence times?[J].J Geophys Res,102(B7):15115—15128.
Wiemer S,Wyss M.2000.Minimum magnitude of completeness in earthquake catalogs:examples from Alaska,thewestern United States,and Japan[J].Bull Seismol Soc Am,90:859—869.
Wyss M,Schorlemmer D,Wiemer S.2000.Mapping asperities by minima of local recurrence time:San Jacinto-Elsi-nore fault zones[J].J Geophys Res,105(B4):7829—7844.
Wyss M and Matsumura S.2002.Most likely location of large earthquakes in the Kanto and Tokai areas,Japan,basedon the local recurrence times[J].Physics of the Earth and Planetary Interiors,131:173—184.
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