历史大地震破裂区地震危险性的地震活动性定量分析——以南北地震带中北段为例
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摘要
尽管地震空区理论在中长期地震预测中起着重要的作用,但大地震复发在时间上的丛集或非线性行为使得在中长期地震预测研究中依然需要同时考虑非地震空区的、历史地震破裂区的潜在大地震危险性。为了探索能基于观测资料分析的、鉴别历史地震破裂区(包括历史、史前地震破裂的地震空区)大地震复发危险性的技术方法,在南北地震带中北段挑选出8个具有不同离逝时间的历史大地震破裂区,分析这些破裂区现代地震活动性的量化特征,以初步探索判定潜在大地震危险性紧迫程度的地震活动性方法。结果表明,反映地震序列衰减状态的p值和反映地震活动率的a值与这些历史破裂区最晚大地震的离逝时间有较好的对应关系,但也有部分破裂区可能由于复杂的断层结构与运动性质,对应关系并不明确;反映构造应力积累状况的b值则难于反映离逝时间演化阶段的信息。b值的时间扫描结果显示,大部分历史破裂区的b值随时间演化平稳,但1879年甘肃武都8级地震破裂区的b值则表现为明显的涨落,并存在持续20年的降低趋势。对比分析认为,1933年四川茂县7.5级、1976年四川松潘—平武两次7.2级地震破裂区目前仍处于序列衰减期,不具备再次发生7级以上地震的背景;公元842年迭部7级地震破裂区北缘低b值的玛曲段比迭部段更具危险性;1879年武都8级地震破裂区的b值持续降低也可能反映该区处于新的一轮孕震期。
Although seismic gap theory plays an important role in mid-long term earthquake prediction,the potential risk of the non-seismic gap,historical rupture area,need to be take into consideration at the same time,during the study of mid-long term earthquake prediction,due to the clustering or non-linear behavior of the large earthquake recurrence time.In order to explore technical methods which can be based on observational data,and can indentify historical earthquake rupture zone(including historical,seismic gap of prehistoric earthquake rupture),we select 8 historical large earthquake ruptures with different elapsed times in the South-North Seismic Belt,analyzing the quantitative characteristics of the modern seismicity of these ruptures,to determine the seismicity method of potential earthquake hazard urgency.The results mainly show that,p value,which reflects the attenuation of the earthquake sequence,and a value,which reflects the seismicity rate,are well related to the elapsed time of the latest earthquake in the rupture,that the corresponding relationships in some rupture areas are not clear may due to the complex fault structure and movement behavior.b value,which represents the state of tectonic stress accumulation,is difficult to reflect the elapsed time information of different evolution stages.b value temporal scanning shows that most of the rupture zone evolution is steady over time,but in the rupture zone of the 1879 Wudu M8 earthquake,the b value is manifested in significant fluctuations,and there is a decreasing trend for 20 years.By comparative analyzing,we conclude that the ruptures of the 1933 Maoxian 7.5,the 1976 twin Songpan-Pingwu 7.2 earthquakes,are still in the sequence decay period.Low b values in the Maqu segment,which locates at the north margin of the 842 Diebu M>7 rupture,is more dangerous than the Diebu segment.Continued reduction of b value in the 1879 Wudu M8 earthquake rupture may also reflect a new round of seismogenic period.
Although seismic gap theory plays an important role in mid-long term earthquake prediction,the potential risk of the non-seismic gap,historical rupture area,need to be take into consideration at the same time,during the study of mid-long term earthquake prediction,due to the clustering or non-linear behavior of the large earthquake recurrence time.In order to explore technical methods which can be based on observational data,and can indentify historical earthquake rupture zone(including historical,seismic gap of prehistoric earthquake rupture),we select 8 historical large earthquake ruptures with different elapsed times in the South-North Seismic Belt,analyzing the quantitative characteristics of the modern seismicity of these ruptures,to determine the seismicity method of potential earthquake hazard urgency.The results mainly show that,p value,which reflects the attenuation of the earthquake sequence,and a value,which reflects the seismicity rate,are well related to the elapsed time of the latest earthquake in the rupture,that the corresponding relationships in some rupture areas are not clear may due to the complex fault structure and movement behavior.b value,which represents the state of tectonic stress accumulation,is difficult to reflect the elapsed time information of different evolution stages.b value temporal scanning shows that most of the rupture zone evolution is steady over time,but in the rupture zone of the 1879 Wudu M8 earthquake,the b value is manifested in significant fluctuations,and there is a decreasing trend for 20 years.By comparative analyzing,we conclude that the ruptures of the 1933 Maoxian 7.5,the 1976 twin Songpan-Pingwu 7.2 earthquakes,are still in the sequence decay period.Low b values in the Maqu segment,which locates at the north margin of the 842 Diebu M>7 rupture,is more dangerous than the Diebu segment.Continued reduction of b value in the 1879 Wudu M8 earthquake rupture may also reflect a new round of seismogenic period.
引文
[1]Mogi K.Two kinds of seismic gaps[J].Pure Appl Geophys,1979,117:1 172-1 186.
[2]Wen X Z,Ma S L,Xu X W,et al.Historical pattern and behavior of earthquake ruptures along theeastern boundary of the Sichuan-Yunan faulted-block,southwestern China[J].Phys Earth Planet In-teriors,2008,doi:10.1016/J.pepi.2008.04.013.
[3]Wells D L,Coppersmith K J.New empirical relationships among magnitude,rupture length,rup-ture width,rupture area,and surface displacement[J].Bull Seismol Soc Am,1995,84(4):974-1 002.
[4]冉勇康,邓起东.海原断裂的古地震及特征地震破裂的分极性讨论[J].第四纪研究,1998,(3):271-278.
[5]Wen Xueze,Yi Guixi,Xu Xiwei.Background and precursory seismicities along and surrounding theKunlun fault before the MS8.1,2001,Kokoxili earthquake,China[J].Journal of Asian Earth Sci-ences,2007,30(1):63-72.doi:10.1016/j.jseaes.2006.07.008.
[6]Scholz C H.The mechanics of earthquakes and faulting[M].Cambridge Univ Press,New York,1990.1-439.
[7]Nishenko S P.Circum-Pacific seismic potential:1989—1999[J].Pure Appl Geophys,1991,35:169-259.
[8]闻学泽,范军,易桂喜,等.川西安宁河断裂上的地震空区[J].中国科学D辑:地球科学,2008,38(7):797-807.
[9]Reid H F.The mechanics of the earthquake,the California earthquake of April 18,1906,report ofthe state investigation commission[M].Vol.2.Carnegie Institution of Washington,Washington DC,1910.
[10]Bufe C G,Harsh P W,Burford R O.Steady-state seismic slip-A precise recurrence model[J].Geo-phys Res Lett,1977,4:91-94.
[11]Shimazaki K,Nakata T.Time-predictable recurrence model for large earthquakes[J].Geophys ResLetters,1980,7:279-282.
[12]Bakun W H,McEvilly T V.Recurrence models and Parkfield,California,earthquakes[J].J Geo-phys Res,1984,89:3 051-3 058.
[13]Ding G Y.The inhomogeneity of Holocene faulting[J].Earthquake Research in China,1991,5(2):95-105.
[14]Xu X W,Deng Q D.Nonlinear characteristics of paleoseismicity in China[J].J Geophys Res,1996,101(B3):6 209-6 231.
[15]Matthews M V,Ellsworth W L,Reasenberg P A.A Brownian model for recurrent earthquakes[J].Bull Seismol Soc Am,2002,92(6):2 233-2 250.
[16]邓起东,陈立春,冉勇康.活动构造定量研究与应用[J].地学前缘,2004,11(4):383-392.
[17]张培震,邓起东,张国民,等.中国大陆的强震活动与活动地块[J].中国科学D辑:地球科学,2003,33(增刊):12-20.
[18]Zhang P,Shen Z K,Wang M.Continuous deformation of the Tibetan Plateau from global positio-ning system data[J].Geology,2004,32(2):809-912.
[19]Shen Z K,LüJ N,Wang M,et al.Contemporary crustal deformation around the southeast border-land of the Tibetan Plateau[J].J Geophy Res,2005,110(B11409).
[20]马保起,苏刚,侯治华,等.利用岷江阶地的变形估算龙门山断裂带中段晚第四纪滑动速率[J].地震地质,2005,27(2):234-242.
[21]Ran Y K,Chen L C,Chen J,et al.Paleoseismic evidence and repeat time of large earthquakes at thesites along the Longmenshan fault zone[J].Tectonophysics,2010,491:141-153.
[22]闻学泽,张培震,杜方,等.2008年汶川8.0级地震发生的历史与现今地震活动背景[J].地球物理学报,2009,52(2):444-454.
[23]闻学泽,杜方,张培震,等.巴颜喀拉块体北和东边界大地震序列的关联性与2008年汶川地震[J].地球物理学报,2011,54(3):706-716.
[24]Fedotov S A.Regularities of the distribution of strong earthquakes in Kamchatka,the KurileIslands,and northeast Japan[J].Tr Inst Fiz Zemli Akad Nauk.SSSR,1965,36:66-93.
[25]Sykes L R.Aftershock zones of great earthquakes,seismicity gaps,and earthquake prediction forAlaska and the Aleutians[J].J Geophys Res,1971,76:8 021-8 041.
[26]易桂喜,闻学泽,徐锡伟.川滇地区若干活动断裂带整体的强地震复发特征研究[J].中国地震,2002,18(3):47-56.
[27]徐锡伟,张培震,闻学泽,等.川西及其邻区活动构造基本特征与强震复发模型[J].地震地质,2005,27(3):446-460.
[28]韩渭宾,蒋国芳.川滇地区强震活动分布特征及其与地壳块体构造背景关系的研究[J].地震学报,2004,26(2):211-222.
[29]Schorlemmer D,Wiemer S.Microseismicity data forecast rupture area[J].Nature,2005,434:1 086,doi:10.1038/4341086a.
[30]Wyss,M,Matsumura S.Verification of our previous definition of preferred earthquake nucleationareas in Kanto-Tokai,Japan[J].Tectonophys,2005,417:81-84.
[31]易桂喜,闻学泽,王思维,等.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强震危险性[J].中国地震,2006,22(2):117-125.
[32]梅世蓉,冯德益,张国民,等.中国地震预报概论[M].北京:地震出版社,1993.
[33]Huang Q,Sobolev G A.Characteristics of the seismic quiescence and activation patterns before theM=7.2Kobe earthquake,January 17,1995[J].Tectonophysics,2001,337:99-116.
[34]易桂喜,闻学泽,范军,等.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,2004,26(3):294-303.
[35]Gutenberg R C,Richter F.Frequency of earthquakes in California[J].Bull Seismol Soc Am,1944,34:185-188.
[36]Wesnousky S G,Scholz C H,Shimazaki K,et al.Earthquake-frequency distribution and the me-chanics of faulting[J].J Geophys Res,1983,88:9 331-9 340.
[37]Wesnousky S G.The Gutenberg-Richter or characteristic earthquake distribution,which is it?[J].Bull Seismol Soc Am,1994,84(6):1 940-1 959.
[38]Scholz C H.The frequency-magnitude relation of microfracturing in rock and its relation to earth-quakes[J].Bull Seismol Soc Am,1968,58:399-415.
[39]Utsu T.A statistical study on the occurrence of aftershocks[J].Geophys Mag,1961,30:526-605.
[40]Felzer K R,Abercrombie R E,Ekstrom G.A common origin for aftershocks,foreshocks,and mul-tiplets[J].Bull Seismol Soc Am,2004,94:88-98.
[41]Helmstetter A,Kagan Y,Jackson D.Importance of small earthquakes for stress transfers andearthquake triggering[J].J Geophys Res,2005,110,B05S08,doi:10.1029/2004JB003286.
[42]Kagan Y.Short-term properties of earthquake catalogues and models of earthquake source[J].BullSeismol Soc Am,2004,94:1 207-1 228.
[43]Nateau C,Shebalin P,Holschneider M.Temporal limits of the power law aftershock decay rate[J].J Geophys Res,2002,107(B12),2 359,doi:10.1029/2002JB001868.
[44]Ogata Y.Statistical models for earthquake occurrences and residual analysis for point processes[J].Journal of American Statistical Association,Application,1988,83(401):9-27.
[45]龙锋,闻学泽,倪四道.区域最小完整性震级时空分布的确定以龙门山断裂带为例[J].地震,2009,29(3):27-36.
[46]Wiemer S,Wyss M.Minimum magnitude of complete reporting in earthquake catalogs:Examplesfrom Alaska,the Western United States,and Japan[J].Bull Seismol Soc Am,2000,90:859-869.
[47]Smith D W.The b-value as an earthquake precursor[J].Nature,1981,289:136-139.
[48]Schorlemmer D,Wiemer S,Wyss M.Variations in earthquake-size distribution across differentstress regimes[J].Nature,2005,437:539-542.
[49]Kato N,Hirasawa T.The variation of stresses due to aseismic sliding and its effect on seismic activ-ity[J].Pure Appl Geophys,1999,155:425-442.
[50]King G C P,Stein R S,Lin J.Static stress changes and the triggering of earthquakes[J].Bull Seis-mol Soc Am,1994,84(3):935-953.
[51]Stein S.The role of stress transfer in earthquake occurrence[J].Nature,1999,402(9):605-609.
[52]朱航,闻学泽.1973—1976年四川松潘强震序列的应力触发过程[J].地球物理学报,2009,52(4):994-1 003.
①http://www.csndmc.ac.cn/newweb/data.htm#
①http://www.geociencias.unam.mx/～ramon/ZMAP/intro.html
[2]Wen X Z,Ma S L,Xu X W,et al.Historical pattern and behavior of earthquake ruptures along theeastern boundary of the Sichuan-Yunan faulted-block,southwestern China[J].Phys Earth Planet In-teriors,2008,doi:10.1016/J.pepi.2008.04.013.
[3]Wells D L,Coppersmith K J.New empirical relationships among magnitude,rupture length,rup-ture width,rupture area,and surface displacement[J].Bull Seismol Soc Am,1995,84(4):974-1 002.
[4]冉勇康,邓起东.海原断裂的古地震及特征地震破裂的分极性讨论[J].第四纪研究,1998,(3):271-278.
[5]Wen Xueze,Yi Guixi,Xu Xiwei.Background and precursory seismicities along and surrounding theKunlun fault before the MS8.1,2001,Kokoxili earthquake,China[J].Journal of Asian Earth Sci-ences,2007,30(1):63-72.doi:10.1016/j.jseaes.2006.07.008.
[6]Scholz C H.The mechanics of earthquakes and faulting[M].Cambridge Univ Press,New York,1990.1-439.
[7]Nishenko S P.Circum-Pacific seismic potential:1989—1999[J].Pure Appl Geophys,1991,35:169-259.
[8]闻学泽,范军,易桂喜,等.川西安宁河断裂上的地震空区[J].中国科学D辑:地球科学,2008,38(7):797-807.
[9]Reid H F.The mechanics of the earthquake,the California earthquake of April 18,1906,report ofthe state investigation commission[M].Vol.2.Carnegie Institution of Washington,Washington DC,1910.
[10]Bufe C G,Harsh P W,Burford R O.Steady-state seismic slip-A precise recurrence model[J].Geo-phys Res Lett,1977,4:91-94.
[11]Shimazaki K,Nakata T.Time-predictable recurrence model for large earthquakes[J].Geophys ResLetters,1980,7:279-282.
[12]Bakun W H,McEvilly T V.Recurrence models and Parkfield,California,earthquakes[J].J Geo-phys Res,1984,89:3 051-3 058.
[13]Ding G Y.The inhomogeneity of Holocene faulting[J].Earthquake Research in China,1991,5(2):95-105.
[14]Xu X W,Deng Q D.Nonlinear characteristics of paleoseismicity in China[J].J Geophys Res,1996,101(B3):6 209-6 231.
[15]Matthews M V,Ellsworth W L,Reasenberg P A.A Brownian model for recurrent earthquakes[J].Bull Seismol Soc Am,2002,92(6):2 233-2 250.
[16]邓起东,陈立春,冉勇康.活动构造定量研究与应用[J].地学前缘,2004,11(4):383-392.
[17]张培震,邓起东,张国民,等.中国大陆的强震活动与活动地块[J].中国科学D辑:地球科学,2003,33(增刊):12-20.
[18]Zhang P,Shen Z K,Wang M.Continuous deformation of the Tibetan Plateau from global positio-ning system data[J].Geology,2004,32(2):809-912.
[19]Shen Z K,LüJ N,Wang M,et al.Contemporary crustal deformation around the southeast border-land of the Tibetan Plateau[J].J Geophy Res,2005,110(B11409).
[20]马保起,苏刚,侯治华,等.利用岷江阶地的变形估算龙门山断裂带中段晚第四纪滑动速率[J].地震地质,2005,27(2):234-242.
[21]Ran Y K,Chen L C,Chen J,et al.Paleoseismic evidence and repeat time of large earthquakes at thesites along the Longmenshan fault zone[J].Tectonophysics,2010,491:141-153.
[22]闻学泽,张培震,杜方,等.2008年汶川8.0级地震发生的历史与现今地震活动背景[J].地球物理学报,2009,52(2):444-454.
[23]闻学泽,杜方,张培震,等.巴颜喀拉块体北和东边界大地震序列的关联性与2008年汶川地震[J].地球物理学报,2011,54(3):706-716.
[24]Fedotov S A.Regularities of the distribution of strong earthquakes in Kamchatka,the KurileIslands,and northeast Japan[J].Tr Inst Fiz Zemli Akad Nauk.SSSR,1965,36:66-93.
[25]Sykes L R.Aftershock zones of great earthquakes,seismicity gaps,and earthquake prediction forAlaska and the Aleutians[J].J Geophys Res,1971,76:8 021-8 041.
[26]易桂喜,闻学泽,徐锡伟.川滇地区若干活动断裂带整体的强地震复发特征研究[J].中国地震,2002,18(3):47-56.
[27]徐锡伟,张培震,闻学泽,等.川西及其邻区活动构造基本特征与强震复发模型[J].地震地质,2005,27(3):446-460.
[28]韩渭宾,蒋国芳.川滇地区强震活动分布特征及其与地壳块体构造背景关系的研究[J].地震学报,2004,26(2):211-222.
[29]Schorlemmer D,Wiemer S.Microseismicity data forecast rupture area[J].Nature,2005,434:1 086,doi:10.1038/4341086a.
[30]Wyss,M,Matsumura S.Verification of our previous definition of preferred earthquake nucleationareas in Kanto-Tokai,Japan[J].Tectonophys,2005,417:81-84.
[31]易桂喜,闻学泽,王思维,等.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强震危险性[J].中国地震,2006,22(2):117-125.
[32]梅世蓉,冯德益,张国民,等.中国地震预报概论[M].北京:地震出版社,1993.
[33]Huang Q,Sobolev G A.Characteristics of the seismic quiescence and activation patterns before theM=7.2Kobe earthquake,January 17,1995[J].Tectonophysics,2001,337:99-116.
[34]易桂喜,闻学泽,范军,等.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,2004,26(3):294-303.
[35]Gutenberg R C,Richter F.Frequency of earthquakes in California[J].Bull Seismol Soc Am,1944,34:185-188.
[36]Wesnousky S G,Scholz C H,Shimazaki K,et al.Earthquake-frequency distribution and the me-chanics of faulting[J].J Geophys Res,1983,88:9 331-9 340.
[37]Wesnousky S G.The Gutenberg-Richter or characteristic earthquake distribution,which is it?[J].Bull Seismol Soc Am,1994,84(6):1 940-1 959.
[38]Scholz C H.The frequency-magnitude relation of microfracturing in rock and its relation to earth-quakes[J].Bull Seismol Soc Am,1968,58:399-415.
[39]Utsu T.A statistical study on the occurrence of aftershocks[J].Geophys Mag,1961,30:526-605.
[40]Felzer K R,Abercrombie R E,Ekstrom G.A common origin for aftershocks,foreshocks,and mul-tiplets[J].Bull Seismol Soc Am,2004,94:88-98.
[41]Helmstetter A,Kagan Y,Jackson D.Importance of small earthquakes for stress transfers andearthquake triggering[J].J Geophys Res,2005,110,B05S08,doi:10.1029/2004JB003286.
[42]Kagan Y.Short-term properties of earthquake catalogues and models of earthquake source[J].BullSeismol Soc Am,2004,94:1 207-1 228.
[43]Nateau C,Shebalin P,Holschneider M.Temporal limits of the power law aftershock decay rate[J].J Geophys Res,2002,107(B12),2 359,doi:10.1029/2002JB001868.
[44]Ogata Y.Statistical models for earthquake occurrences and residual analysis for point processes[J].Journal of American Statistical Association,Application,1988,83(401):9-27.
[45]龙锋,闻学泽,倪四道.区域最小完整性震级时空分布的确定以龙门山断裂带为例[J].地震,2009,29(3):27-36.
[46]Wiemer S,Wyss M.Minimum magnitude of complete reporting in earthquake catalogs:Examplesfrom Alaska,the Western United States,and Japan[J].Bull Seismol Soc Am,2000,90:859-869.
[47]Smith D W.The b-value as an earthquake precursor[J].Nature,1981,289:136-139.
[48]Schorlemmer D,Wiemer S,Wyss M.Variations in earthquake-size distribution across differentstress regimes[J].Nature,2005,437:539-542.
[49]Kato N,Hirasawa T.The variation of stresses due to aseismic sliding and its effect on seismic activ-ity[J].Pure Appl Geophys,1999,155:425-442.
[50]King G C P,Stein R S,Lin J.Static stress changes and the triggering of earthquakes[J].Bull Seis-mol Soc Am,1994,84(3):935-953.
[51]Stein S.The role of stress transfer in earthquake occurrence[J].Nature,1999,402(9):605-609.
[52]朱航,闻学泽.1973—1976年四川松潘强震序列的应力触发过程[J].地球物理学报,2009,52(4):994-1 003.
①http://www.csndmc.ac.cn/newweb/data.htm#
①http://www.geociencias.unam.mx/～ramon/ZMAP/intro.html
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