传染型余震序列模型震后早期参数特征及其地震学意义
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摘要
研究中国大陆地区中强地震序列震后早期阶段(震后15天)ETAS模型参数的平均统计特征,据此讨论不同统计条件下的序列衰减及余震激发问题.宏观而言,模型参数b、p、α数值分布较为离散,不同统计条件下模型参数平均值的差异显著性不十分突出.详细对比不同统计条件下模型参数平均值的微小差异,b值随主震震级增大而增大,但b值随不同区域、不同主震断层类型或不同序列类型的变化不明显.p、α具有一定的区域特征,西南、西北p值略低于新疆及华北,表明西南、西北序列衰减相对较慢而新疆、华北序列衰减相对较快,华北α较低而西北α相对最高,意味着尽管华北序列衰减相对较快,但其激发高阶余震的能力却相对强,西北尽管序列衰减较慢,但序列结构单一,激发高阶余震的能力弱.p与主震断层类型关系不明显,即主震破裂性质不是决定序列衰减快慢的主要因素;α与主震断层类型有一定关系,走滑-近走滑型破裂所导致序列的α值最小、斜滑型次之、倾滑-近倾滑型最大,表明走滑-近走滑型序列激发高阶余震的能力最强、逆冲型最弱、斜滑型居中.p、α随主震震级增大而减小,意味着主震震级越高则序列衰减越慢、激发高阶余震的能力越强.不同类型序列p、α有一定差异,主余型序列p最小、孤立型p最大,表明相对而言主余型序列衰减最慢、孤立型序列衰减最快、多震型序列衰减速率居中.孤立型序列与主余型序列α大体一致、大于多震型序列的α值,即多震型序列激发高阶余震的能力相对最强,孤立型及主余型序列则相对较弱.
The average statistical features of ETAS(Epidemic Type Aftershock Sequence) model parameters during the earlier stage(15 days) after the moderate or large earthquakes in Chinese mainland have been studied and the decay and generation of aftershocks under the different conditions also have been discussed.Macroscopically,the numerical distribution of primary parameters of ETAS model,b,p,and α,are dispersed and the differences of average value of parameters under the different conditions are not very prominent.In detail,b-value increases with the magnitude of the mainshock,but the differences of b-value are not obvious for different regions,for different modes of mainshock fracture,as well as for different sequence types.p-value and α-value show some regional features to some extent.Average p-values in southwest and northwest region of China are a little larger than that in Xinjiang and in North China,this means that the decay of aftershock activity is a little slower in southwest region and in northwest region than that in Xinjiang and in North China.Average α-value is small in northwest region,and is large in North China.This indicates that the earthquake in North China has a high ability to generate high-order aftershocks,although the aftershock decay in North China is relatively quick.And for northwest region of China,despite the slow aftershock decay,but due to the simplicity of aftershock sequence,the ability of high-order aftershock generation is weak.The relation between p-value and the fracture mode of the mainshock is not evident,that is,the mainshock fracture mode is not the key factor controlling the aftershock decay rate.α-value is related to the mainshock fracture mode to some extent.Averagely,α-value is small for strike-slip,middle for oblique slip and large for dip slip.This means that strike-slipping has the highest ability to generate aftershocks,it is weakest for dip slip and middle for oblique slip.p-value and α-value decrease with the increment of the mainshock magnitude,this means that the larger the mainshock,the slower the sequence decay and the higher the ability to generate offspring.There are some differences in p-values and α-values for different sequence types.p-value is smaller for mainshock-aftershock type(MAT) and larger for isolated earthquake type(IET),this indicates that decay rate of aftershock is slow for MAT,is quick for IET and is in the middle for multiple mainshock type(MMT).α-values of IET and MAT are about the same,both two are larger than that of MMT.This means that MMT has a higher ability to generate high-order aftershocks than that of IET and MAT.
The average statistical features of ETAS(Epidemic Type Aftershock Sequence) model parameters during the earlier stage(15 days) after the moderate or large earthquakes in Chinese mainland have been studied and the decay and generation of aftershocks under the different conditions also have been discussed.Macroscopically,the numerical distribution of primary parameters of ETAS model,b,p,and α,are dispersed and the differences of average value of parameters under the different conditions are not very prominent.In detail,b-value increases with the magnitude of the mainshock,but the differences of b-value are not obvious for different regions,for different modes of mainshock fracture,as well as for different sequence types.p-value and α-value show some regional features to some extent.Average p-values in southwest and northwest region of China are a little larger than that in Xinjiang and in North China,this means that the decay of aftershock activity is a little slower in southwest region and in northwest region than that in Xinjiang and in North China.Average α-value is small in northwest region,and is large in North China.This indicates that the earthquake in North China has a high ability to generate high-order aftershocks,although the aftershock decay in North China is relatively quick.And for northwest region of China,despite the slow aftershock decay,but due to the simplicity of aftershock sequence,the ability of high-order aftershock generation is weak.The relation between p-value and the fracture mode of the mainshock is not evident,that is,the mainshock fracture mode is not the key factor controlling the aftershock decay rate.α-value is related to the mainshock fracture mode to some extent.Averagely,α-value is small for strike-slip,middle for oblique slip and large for dip slip.This means that strike-slipping has the highest ability to generate aftershocks,it is weakest for dip slip and middle for oblique slip.p-value and α-value decrease with the increment of the mainshock magnitude,this means that the larger the mainshock,the slower the sequence decay and the higher the ability to generate offspring.There are some differences in p-values and α-values for different sequence types.p-value is smaller for mainshock-aftershock type(MAT) and larger for isolated earthquake type(IET),this indicates that decay rate of aftershock is slow for MAT,is quick for IET and is in the middle for multiple mainshock type(MMT).α-values of IET and MAT are about the same,both two are larger than that of MMT.This means that MMT has a higher ability to generate high-order aftershocks than that of IET and MAT.
引文
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[2]Ogata Y.Statistical model for earthquake occurrence and residualanalysis for point processes.Journal of the American StatisticalAssociation,1988,17:97~105
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[7]Ogata Y.Detection of precursory relative quiescence before greatearthquakes through a statistical model.JGR,1992,97:19845~19871
[8]Ogata Y.Increased probability of large earthquake near aftershockregions with relative quiescence.JGR,2001,106(B5):8729~8744
[9]Agnes Helmstetter,Didier Somette.Importance of direct and indirecttriggered seismicity in ETAS model of seismicity.GeophysicalResearch Letters,2003,30(11):1576,30-1~30-4
[10]庄建仓,马丽.主震和余震——从大森公式到ETAS模型.国际地震动态,2000,(5):12~17Zhuang J C,Ma L.Mainshock and aftershock——from Omori law toETAS model.Recent Development in World Seismology(in Chinese),2000,(5):12~17
[11]Ma L,Zhuang J C.Relative quiescence within Jiashi swarm inXinjiang,China:An application of the ETAS point process model.J.Appl.Probbab,2001,38(A):213~221
[12]刘文兵,马丽.台湾集集地震和华北大同地震序列的定量模型分析.地震,2004,24(1):155~161Liu W B,Ma L.The analysis between two seismic sequences of Chi-Chi,Taiwan and Datong,North China with the quantitative mode.Earthquake(in Chinese),2004,24(1):155~161
[13]Utsu T.Statistical study on the occurrence of aftershocks.Geophys.Mag.,1961,30:521~605
[14]Mogi K.Magnitude-frequency relation for elastic shocksaccompanying fractures of various materials and some related problemsin earthquakes.Bull.Earthq.Res.Inst.,1962,40(2):831~853
[15]Scholz C H.The frequency-magnitude relation of microfracturing inrock and its relation to earthquakes.BSSA,1968,58:399~415
[16]耿乃光.b值模拟实验的进展和我国b值模拟实验的开端.地震学报,1986,8(3):330~333Geng N G.Progress of simulating experiments onbvalue and theorigin of simulating experiments onbvalue in Chinese Mainland.Acta Seismologica Sinica(in Chinese),1986,8(3):330~333
[17]Utsu T.Aftershocks and earthquake statistics(3).J.Fac.Sci.Hokkaido Univ.,1971,7(3):379~441
[18]Reasenberg P A,Lucile M Jones.Earthquake hazard after amainshock in California.Science,1989,243:1173~1176
[19]蒋海昆,曲延军,李永莉等.中国大陆中强地震余震序列的部分统计特征.地球物理学报,2006,49(4):1110~1117Jiang H K,Qu Y J,Li Y L,et al.Some statistic features ofaftershock sequences in Chinese Mainland.Chinese J.Geophys.(inChinese),2006,49(4):1110~1117
[20]蒋海昆,李永莉,曲延军等.中国大陆中强地震序列类型空间分布特征.地震学报,2006,28(4):389~398Jiang H K,Li Y L,Qu Y J,et al.Spatial distribution features ofsequence types of moderate-and large earthquake in Chinesemainland.Acta Seismologica Sinica,2006,19(4):417~427
[21]蒋海昆,郑建常,吴琼等.中国大陆中强以上地震余震分布尺度的统计特征.地震学报,2007,29(2):151~164Jiang H K,Zheng J C,Wu Q,et al.Statistical features of aftershockdistribution size for moderate or large earthquakes in Chinesemainland.Acta Seismologica Sinica(in Chinese),2007,20(2):158~171
[22]Reasenberg P A.Foreshock occurrence before large earthquakes.JGR,1999,104(B3),4755~4768
[23]许忠淮.震源机制.见:中国地震局监测预报司主编.地震参数——数字地震学在地震预测中的运用.北京:地震出版社,2003.16~25Xu Z H.Seismic mechanism.In:Department of EarthquakeMonitoring and Prediction,CEA eds.Seismic Parameters:Application of Digital Seismology in the Earthquake Forecasting(inChinese).Beijing:Seismological Press,2003.16~25
[24]周翠英,王铮铮,蒋海昆等.华东地区现代地壳应力场及地震断层错动性质.地震地质,2005,27(2):273~288Zhou C Y,Wang Z Z,Jiang H K,et al.Contemporary crustal stressfield and feature of earthquake fault slip in East China.Seismologyand Geology(in Chinese),2005,27(2):273~288
[25]单新建,何玉梅,朱燕等.伽师强震群震源破裂特征的初步分析.地球物理学报,2002,45(3):416~425Shan X J,He Y M,Zhu Y,et al.A preliminary analysis on rupturecharacteristics of Jiashi strong earthquake swarm.Chinese J.Geophys.(in Chinese),2002,45(3):416~425
[26]焦远碧.地震序列类型、地震序列b值与地震大形势关系初探.地震,1998,18(1):33~39Jiao Y B.Discussion on the relationship between types andbvalue ofearthquake sequences with the seismic tendency.Earthquake(inChinese),1998,18(1):33~39
[27]王筱荣,孙甲宁,王季达.新疆伽师强震群与其他典型强震群对比研究.内陆地震,2006,20(2):121~130Wang X R,Sun J N,Wang J D.Comparing study on Jiashi strongswarm,Xianjiang,with other typical strong swarms.InlandEarthquake(in Chinese),2006,20(2):121~130
[28]蒋海昆,代磊,侯海峰等.余震序列性质判定单参数判据的统计研究.地震,2006,26(3):17~25Jiang H K,Dai L,Hou H F,et al.Statistic study on the criterionindex for classification of aftershock sequences.Earthquake(inChinese),2006,26(3):17~25
[2]Ogata Y.Statistical model for earthquake occurrence and residualanalysis for point processes.Journal of the American StatisticalAssociation,1988,17:97~105
[3]Ogata Y.Statistical model for standard seismicity and detection ofanomalies by residual analysis for point processes.Tectonophysics,1989,83:9~27
[4]Utsu T,Ogata Y,Matsuura R S.The centenary of the Omori formulafor a decay law of aftershock activity.J.Phys.Earth.,1995,43(1):1~33
[5]Ogata Y.Space-time point-process models for earthquakeoccurrences.Ann.Inst.Stat.Math.,1998,50:379~402
[6]Guo Zhenqi,Ogata Y.Statistical relations between the parameters ofaftershocks in time,space,and magnitude.JGR,1997,102(B2):2857~2873
[7]Ogata Y.Detection of precursory relative quiescence before greatearthquakes through a statistical model.JGR,1992,97:19845~19871
[8]Ogata Y.Increased probability of large earthquake near aftershockregions with relative quiescence.JGR,2001,106(B5):8729~8744
[9]Agnes Helmstetter,Didier Somette.Importance of direct and indirecttriggered seismicity in ETAS model of seismicity.GeophysicalResearch Letters,2003,30(11):1576,30-1~30-4
[10]庄建仓,马丽.主震和余震——从大森公式到ETAS模型.国际地震动态,2000,(5):12~17Zhuang J C,Ma L.Mainshock and aftershock——from Omori law toETAS model.Recent Development in World Seismology(in Chinese),2000,(5):12~17
[11]Ma L,Zhuang J C.Relative quiescence within Jiashi swarm inXinjiang,China:An application of the ETAS point process model.J.Appl.Probbab,2001,38(A):213~221
[12]刘文兵,马丽.台湾集集地震和华北大同地震序列的定量模型分析.地震,2004,24(1):155~161Liu W B,Ma L.The analysis between two seismic sequences of Chi-Chi,Taiwan and Datong,North China with the quantitative mode.Earthquake(in Chinese),2004,24(1):155~161
[13]Utsu T.Statistical study on the occurrence of aftershocks.Geophys.Mag.,1961,30:521~605
[14]Mogi K.Magnitude-frequency relation for elastic shocksaccompanying fractures of various materials and some related problemsin earthquakes.Bull.Earthq.Res.Inst.,1962,40(2):831~853
[15]Scholz C H.The frequency-magnitude relation of microfracturing inrock and its relation to earthquakes.BSSA,1968,58:399~415
[16]耿乃光.b值模拟实验的进展和我国b值模拟实验的开端.地震学报,1986,8(3):330~333Geng N G.Progress of simulating experiments onbvalue and theorigin of simulating experiments onbvalue in Chinese Mainland.Acta Seismologica Sinica(in Chinese),1986,8(3):330~333
[17]Utsu T.Aftershocks and earthquake statistics(3).J.Fac.Sci.Hokkaido Univ.,1971,7(3):379~441
[18]Reasenberg P A,Lucile M Jones.Earthquake hazard after amainshock in California.Science,1989,243:1173~1176
[19]蒋海昆,曲延军,李永莉等.中国大陆中强地震余震序列的部分统计特征.地球物理学报,2006,49(4):1110~1117Jiang H K,Qu Y J,Li Y L,et al.Some statistic features ofaftershock sequences in Chinese Mainland.Chinese J.Geophys.(inChinese),2006,49(4):1110~1117
[20]蒋海昆,李永莉,曲延军等.中国大陆中强地震序列类型空间分布特征.地震学报,2006,28(4):389~398Jiang H K,Li Y L,Qu Y J,et al.Spatial distribution features ofsequence types of moderate-and large earthquake in Chinesemainland.Acta Seismologica Sinica,2006,19(4):417~427
[21]蒋海昆,郑建常,吴琼等.中国大陆中强以上地震余震分布尺度的统计特征.地震学报,2007,29(2):151~164Jiang H K,Zheng J C,Wu Q,et al.Statistical features of aftershockdistribution size for moderate or large earthquakes in Chinesemainland.Acta Seismologica Sinica(in Chinese),2007,20(2):158~171
[22]Reasenberg P A.Foreshock occurrence before large earthquakes.JGR,1999,104(B3),4755~4768
[23]许忠淮.震源机制.见:中国地震局监测预报司主编.地震参数——数字地震学在地震预测中的运用.北京:地震出版社,2003.16~25Xu Z H.Seismic mechanism.In:Department of EarthquakeMonitoring and Prediction,CEA eds.Seismic Parameters:Application of Digital Seismology in the Earthquake Forecasting(inChinese).Beijing:Seismological Press,2003.16~25
[24]周翠英,王铮铮,蒋海昆等.华东地区现代地壳应力场及地震断层错动性质.地震地质,2005,27(2):273~288Zhou C Y,Wang Z Z,Jiang H K,et al.Contemporary crustal stressfield and feature of earthquake fault slip in East China.Seismologyand Geology(in Chinese),2005,27(2):273~288
[25]单新建,何玉梅,朱燕等.伽师强震群震源破裂特征的初步分析.地球物理学报,2002,45(3):416~425Shan X J,He Y M,Zhu Y,et al.A preliminary analysis on rupturecharacteristics of Jiashi strong earthquake swarm.Chinese J.Geophys.(in Chinese),2002,45(3):416~425
[26]焦远碧.地震序列类型、地震序列b值与地震大形势关系初探.地震,1998,18(1):33~39Jiao Y B.Discussion on the relationship between types andbvalue ofearthquake sequences with the seismic tendency.Earthquake(inChinese),1998,18(1):33~39
[27]王筱荣,孙甲宁,王季达.新疆伽师强震群与其他典型强震群对比研究.内陆地震,2006,20(2):121~130Wang X R,Sun J N,Wang J D.Comparing study on Jiashi strongswarm,Xianjiang,with other typical strong swarms.InlandEarthquake(in Chinese),2006,20(2):121~130
[28]蒋海昆,代磊,侯海峰等.余震序列性质判定单参数判据的统计研究.地震,2006,26(3):17~25Jiang H K,Dai L,Hou H F,et al.Statistic study on the criterionindex for classification of aftershock sequences.Earthquake(inChinese),2006,26(3):17~25
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