从同震和震后形变分析日本东北M_W 9.0级大地震对近场地震活动性的影响
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摘要
2011年日本东北大地震后,不断有报道认为日本南海海槽可能会发生强震,日本东北大地震对南海海槽断层活动有何影响?本文采用粘弹性半无限空间模型,利用反演得到的日本东北大地震的断层模型,计算了岛内部分断层的同震和震后形变以及库仑应力变化.结果表明:2011年日本东北大地震,使得平行于日本海沟的岛内逆冲断层应力释放明显,5km深度,库仑应力降低值都在50kPa以上,按照该地区每年应力积累1～10kPa计算,相当于释放了5～50年的应力积累;平行于南海海槽的岛内逆冲断层,同震库仑应力增加了1kPa左右,相当于0.1～1年的正常构造运动应力积累;对于岛内的走滑断层,若其滑动方向与同震或震后形变方向一致,则库仑应力增加,反之则降低,如1948年福井地震发震断层库仑应力增加10kPa左右,相当于1～10年的正常构造运动应力积累,地震危险性明显增加.同时,分析了不同软流圈粘滞性对震后形变和库仑应力的影响,发现对于不同的软流圈粘滞性系数,震后的形变和库仑应力相比同震都会有所增加.因此,对于平行南海海槽的岛内逆冲断层和岛内部分滑动方向与同震形变一致的走滑断层,震后地震危险性相比同震会进一步增强.
After the occurrence of 2011 Tohoku MW 9.0 earthquake,there have been many reports that a strong earthquake maybe occur in Nankai Trough in the future.Does the Tohoku earthquake impact on the seismic activity of Nankai Trough fault? In this paper,with the viscoelastic half-space model,we calculated the coseismic and postseismic deformation and Coulomb stress change of many faults in the Japanese archipelago.The results show that: in the 5 km,the 2011 Tohoku MW 9.0 earthquake makes the coseismic Coulomb stress of thrust faults paralleling to the Japan Trench release more than 50 kPa,which is equivalent to the stress accumulation of 5~50 years.While for the thrust faults in the Japanese archipelago paralleling to the Nankai Trough,the coseismic Coulomb stress increase by 1 kPa,which is equivalent to 0.1~1 years stress accumulation on the case of tectonic movement.For the strike-slip faults,if the sliding direction of the fault is the same with the coseismic displacement,the Coulomb stress will increase,and vice versa.For instance,the Coulomb stress in the fault of 1948 Fukui earthquake increase 10 kPa and the seismic risk is increase significantly.The effect of asthenospheric viscosity on the post-deformation is investigated.We find that the displacement and Coulomb stress will be further increase for most of the faults in the postseismic phase.Therefore,the seismic risk of the thrust fault paralleling to the Nankai Trough and many strike-slip faults whose sliding direction agrees with coseismic displacement,will be enhanced in the future.
After the occurrence of 2011 Tohoku MW 9.0 earthquake,there have been many reports that a strong earthquake maybe occur in Nankai Trough in the future.Does the Tohoku earthquake impact on the seismic activity of Nankai Trough fault? In this paper,with the viscoelastic half-space model,we calculated the coseismic and postseismic deformation and Coulomb stress change of many faults in the Japanese archipelago.The results show that: in the 5 km,the 2011 Tohoku MW 9.0 earthquake makes the coseismic Coulomb stress of thrust faults paralleling to the Japan Trench release more than 50 kPa,which is equivalent to the stress accumulation of 5~50 years.While for the thrust faults in the Japanese archipelago paralleling to the Nankai Trough,the coseismic Coulomb stress increase by 1 kPa,which is equivalent to 0.1~1 years stress accumulation on the case of tectonic movement.For the strike-slip faults,if the sliding direction of the fault is the same with the coseismic displacement,the Coulomb stress will increase,and vice versa.For instance,the Coulomb stress in the fault of 1948 Fukui earthquake increase 10 kPa and the seismic risk is increase significantly.The effect of asthenospheric viscosity on the post-deformation is investigated.We find that the displacement and Coulomb stress will be further increase for most of the faults in the postseismic phase.Therefore,the seismic risk of the thrust fault paralleling to the Nankai Trough and many strike-slip faults whose sliding direction agrees with coseismic displacement,will be enhanced in the future.
引文
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[2]徐纪人,赵志新,河野芳辉,等.日本南海海槽地震区域应力场及其板块构造动力学特征[J].地球物理学报,2003,46(4):488-494.Xu J R,Zhao Z X,Kono Y,et al.Regional characteristics ofstress field and its dynamics in and around the Nankai trough,Japan[J].Chinese J.Geophys.(in Chinese),2003,46(4):488-494.
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[5]Harris R A.Introduction to special section:Stress triggers,stress shadows,and implications for seismic hazard[J].Journal of Geophysical Research,1998,103(B10):24347-24358.
[6]Koketsu K,Yoshida S,Higashihara H.A fault model of the1995 Kobe earthquake derived from the GPS data on theAkashi Kaikyo Bridge and other datasets[J].Earth,Planetsand Space,1998,50:803-811.
[7]Toda S,Enescu B.Rate/state Coulomb stress transfer modelfor the CSEP Japan seismicity forecast[J].Earth,Planets andSpace,2011,63(3):171-185.
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[10]郝金来,王卫民,姚振兴.2011年3月11日日本东北沿海MW9.0级地震震源破裂过程[J].中国科学:地球科学,2011,41(6):745-749.Hao J L,Wang W M,Yao Z X.Source process of the 2011MW9.0Tohuko Japan earthquake[J].Science China:EarthScience,2011,54(8):1105-1109.
[11]邵志刚,武艳强,江在森,等.基于GPS观测分析日本9.0级地震同震位错与近场形变特征[J].地球物理学报,2011,54(9):2243-2249.Shao Z G,Wu Y Q,Jiang Z S,et al.The analysis ofcoseismic slip and near-field deformation about Japanese 9.0earthquake based on the GPS observation[J].Chinese J.Geophys.(in Chinese),2011,54(9):2243-2249.
[12]王敏,李强,王凡,等.全球定位系统测定的2011年日本宫城MW9.0级地震远场同震位移[J].科学通报,2011,56(20):1593-1596.Wang M,Li Q,Wang F,et al.Far-field coseismicdisplacements associated with the 2011 Tohoku-okiearthquake in Japan observed by Global Positioning System[J].Chinese Science Bulletin,2011,56(23):2419-2424.
[13]吴佳翼,郁曙君,何淑韵.华北地震同日本地震的相关性[J].地球物理学报,1979,22(4):415-438.Wu J Y,Yu S J,He S Y.The correlation of earthquakeoccurrence between northeastern China and Japan[J].Chinese J.Geophys.(in Chinese),1979,22(4):415-438.
[14]孙文斌,和跃时,李英波.日本海区板块俯冲与华北地震[J].地震学报,1985,7(1):33-44.Sun W B,He Y S,Li Y B.Subduction of the Pacific plate inthe sea of Japan and earthquakes of northeastern China[J].Acta Seismologica Sinica(in Chinese),1985,7(1):33-44.
[15]Okada Y.Internal deformation due to shear and tensile faultsin a half-space[J].Bulletin of the Seismological Society ofAmerica,1992,82(2):1018-1040.
[16]石耀霖.关于应力触发和应力影概念在地震预报中应用的一些思考[J].地震,2001,21(3):1-7.Shi Y L.Stress triggers and stress shadows:How to applythese concepts to earthquake prediction[J].Earthquake(inChinese),2001,21(3):1-7.
[17]Wang R J,Lorenzo-Martín F,Roth F.PSGRN/PSCMP-anew code for calculating co-and post-seismic deformation,geoid and gravity changes based on the viscoelastic-gravitational dislocation theory[J].Computers&Geosciences,2006,32(4):527-541.
[18]Zhao D P,Hasegawa A,Horiuchi S.Tomographic imagingof P and S wave velocity structure beneath northeastern Japan[J].Journal of Geophysical Research,1992,97(B13):19909-19928.
[19]Zhao D P,Wang Z,Umino N,et al.Mapping the mantlewedge and interplate thrust zone of the northeast Japan arc[J].Tectonophysics,2009,467(1-4):89-106.
[20]Rydelek P A,Sacks I S.Asthenospheric viscosity inferredfrom correlated land-sea earthquakes in north-east Japan[J].Nature,1988,336(6196):234-237.
[21]石耀霖,曹建玲.库仑应力计算及应用过程中若干问题的讨论—以汶川地震为例[J].地球物理学报,2010,53(1):102-110.Shi Y L,Cao J L.Some aspects in static stress changecalculation-case study on Wenchuan earthquake[J].ChineseJ.Geophysics.(in Chinese),2010,53(1):102-110.
[22]King G C P,Stein R S,Lin J.Static stress changes and thetriggering of earthquakes[J].Bulletin of the SeismologicalSociety of America,1994,84(3):935-953.
[23]万永革,吴忠良,周公威,等.地震应力触发研究[J].地震学报,2002,24(5):533-551.Wan Y G,Wu Z L,Zhou G W,et al.Research on seismicstress triggering[J].Acta Seismologica Sinica(in Chinese),2002,24(5):533-551.
[24]Okamoto T,Yamada Y,Noda S.Estimation of sloshing waveheight in vicinity of source region[A].//Proceedings of the9th Word Conference on Earthquake Engineering[C].1988,VI:607-612.
[25]Kanamori H.Determination of effective tectonic stress associatedwith earthquake faulting.The Tottori earthquake of 1943[J].Physics of the Earth and Planetary Interiors,1972,5:426-434.
[26]Kanamori H.Tectonic implications of the 1944Tonankai andthe 1946Nankaido earthquakes[J].Physics of the Earth andPlanetary Interiors,1972,5:129-139.
[27]Ichinose G A,Thio H K,Somerville P G.Rupture process ofthe 1944Tonankai earthquake(Ms 8.1)from the inversionof teleseismic and regional seismograms[J].Journal ofGeophysical Research,2003,108(B10):2497.
[28]Ando M.A fault model of the 1946Nankaido earthquake derivedfrom tsunami data[J].Physics of the Earth and PlanetaryInteriors,1982,28(4):320-336.
[29]Ichinose G A,Somerville P,Thio H K,eta l.Rupture process ofthe 1948Fukui earthquake(M 7.1)from the joint inversionof seismic waveform and geodetic data[J].Journal ofGeophysical Research,2005,110:B05301.
[30]Ide S,Takeo M,Yoshida Y.Source process of the 1995Kobeearthquake:Determination of spatio-temporal slipdistribution by Bayesian modeling[J].Bull.Seism.Soc.Am.,1996,86(3):547-566.
[31]Sagiya T,Miyazaki S,Tada T.Continuous GPS array andPresent-day Crustal deformation of Japan[J].Pure andApplied Geophysics,2000,157(11-12):2303-2322.
[2]徐纪人,赵志新,河野芳辉,等.日本南海海槽地震区域应力场及其板块构造动力学特征[J].地球物理学报,2003,46(4):488-494.Xu J R,Zhao Z X,Kono Y,et al.Regional characteristics ofstress field and its dynamics in and around the Nankai trough,Japan[J].Chinese J.Geophys.(in Chinese),2003,46(4):488-494.
[3]Geller R J.Shake-up time for Japanese seismology[J].Nature,2011,472(7344):407-409.
[4]Yonekura N.Quaternary tectonic movements in the outer arcon southwest Japan with special reference to seismic crustaldeformation[J].Bulletin Department of Geography Universityof Tokyo,1975,7:19-71.
[5]Harris R A.Introduction to special section:Stress triggers,stress shadows,and implications for seismic hazard[J].Journal of Geophysical Research,1998,103(B10):24347-24358.
[6]Koketsu K,Yoshida S,Higashihara H.A fault model of the1995 Kobe earthquake derived from the GPS data on theAkashi Kaikyo Bridge and other datasets[J].Earth,Planetsand Space,1998,50:803-811.
[7]Toda S,Enescu B.Rate/state Coulomb stress transfer modelfor the CSEP Japan seismicity forecast[J].Earth,Planets andSpace,2011,63(3):171-185.
[8]王凡,沈正康,王阎昭,等.2011年3月11日日本宫城MW9.0级地震对其周边地区火山活动的影响[J].科学通报,2011,56(14):1080-1083.Wang F,Shen Z K,Wang Y Z,et al.Influence of the March11,2011 MW9.0Tohoku-oki earthquake on regional volcanicactivities[J].Chinese Science Bulletin,2011,56(20):2077-2081.
[9]刁法启,熊熊,倪四道,等.利用GPS位移反演日本MW9.0仙台地震及MW7.9强余震静态位错模型[J].科学通报,2011,56(24):1999-2005.Diao F Q,Xiong X,Ni S D,et al.Slip model for the 2011 MW9.0Sendai(Japan)earthquake and its MW7.9aftershockderived from GPS data[J].Chinese Science Bulletin,2011,56(27):2941-2947.
[10]郝金来,王卫民,姚振兴.2011年3月11日日本东北沿海MW9.0级地震震源破裂过程[J].中国科学:地球科学,2011,41(6):745-749.Hao J L,Wang W M,Yao Z X.Source process of the 2011MW9.0Tohuko Japan earthquake[J].Science China:EarthScience,2011,54(8):1105-1109.
[11]邵志刚,武艳强,江在森,等.基于GPS观测分析日本9.0级地震同震位错与近场形变特征[J].地球物理学报,2011,54(9):2243-2249.Shao Z G,Wu Y Q,Jiang Z S,et al.The analysis ofcoseismic slip and near-field deformation about Japanese 9.0earthquake based on the GPS observation[J].Chinese J.Geophys.(in Chinese),2011,54(9):2243-2249.
[12]王敏,李强,王凡,等.全球定位系统测定的2011年日本宫城MW9.0级地震远场同震位移[J].科学通报,2011,56(20):1593-1596.Wang M,Li Q,Wang F,et al.Far-field coseismicdisplacements associated with the 2011 Tohoku-okiearthquake in Japan observed by Global Positioning System[J].Chinese Science Bulletin,2011,56(23):2419-2424.
[13]吴佳翼,郁曙君,何淑韵.华北地震同日本地震的相关性[J].地球物理学报,1979,22(4):415-438.Wu J Y,Yu S J,He S Y.The correlation of earthquakeoccurrence between northeastern China and Japan[J].Chinese J.Geophys.(in Chinese),1979,22(4):415-438.
[14]孙文斌,和跃时,李英波.日本海区板块俯冲与华北地震[J].地震学报,1985,7(1):33-44.Sun W B,He Y S,Li Y B.Subduction of the Pacific plate inthe sea of Japan and earthquakes of northeastern China[J].Acta Seismologica Sinica(in Chinese),1985,7(1):33-44.
[15]Okada Y.Internal deformation due to shear and tensile faultsin a half-space[J].Bulletin of the Seismological Society ofAmerica,1992,82(2):1018-1040.
[16]石耀霖.关于应力触发和应力影概念在地震预报中应用的一些思考[J].地震,2001,21(3):1-7.Shi Y L.Stress triggers and stress shadows:How to applythese concepts to earthquake prediction[J].Earthquake(inChinese),2001,21(3):1-7.
[17]Wang R J,Lorenzo-Martín F,Roth F.PSGRN/PSCMP-anew code for calculating co-and post-seismic deformation,geoid and gravity changes based on the viscoelastic-gravitational dislocation theory[J].Computers&Geosciences,2006,32(4):527-541.
[18]Zhao D P,Hasegawa A,Horiuchi S.Tomographic imagingof P and S wave velocity structure beneath northeastern Japan[J].Journal of Geophysical Research,1992,97(B13):19909-19928.
[19]Zhao D P,Wang Z,Umino N,et al.Mapping the mantlewedge and interplate thrust zone of the northeast Japan arc[J].Tectonophysics,2009,467(1-4):89-106.
[20]Rydelek P A,Sacks I S.Asthenospheric viscosity inferredfrom correlated land-sea earthquakes in north-east Japan[J].Nature,1988,336(6196):234-237.
[21]石耀霖,曹建玲.库仑应力计算及应用过程中若干问题的讨论—以汶川地震为例[J].地球物理学报,2010,53(1):102-110.Shi Y L,Cao J L.Some aspects in static stress changecalculation-case study on Wenchuan earthquake[J].ChineseJ.Geophysics.(in Chinese),2010,53(1):102-110.
[22]King G C P,Stein R S,Lin J.Static stress changes and thetriggering of earthquakes[J].Bulletin of the SeismologicalSociety of America,1994,84(3):935-953.
[23]万永革,吴忠良,周公威,等.地震应力触发研究[J].地震学报,2002,24(5):533-551.Wan Y G,Wu Z L,Zhou G W,et al.Research on seismicstress triggering[J].Acta Seismologica Sinica(in Chinese),2002,24(5):533-551.
[24]Okamoto T,Yamada Y,Noda S.Estimation of sloshing waveheight in vicinity of source region[A].//Proceedings of the9th Word Conference on Earthquake Engineering[C].1988,VI:607-612.
[25]Kanamori H.Determination of effective tectonic stress associatedwith earthquake faulting.The Tottori earthquake of 1943[J].Physics of the Earth and Planetary Interiors,1972,5:426-434.
[26]Kanamori H.Tectonic implications of the 1944Tonankai andthe 1946Nankaido earthquakes[J].Physics of the Earth andPlanetary Interiors,1972,5:129-139.
[27]Ichinose G A,Thio H K,Somerville P G.Rupture process ofthe 1944Tonankai earthquake(Ms 8.1)from the inversionof teleseismic and regional seismograms[J].Journal ofGeophysical Research,2003,108(B10):2497.
[28]Ando M.A fault model of the 1946Nankaido earthquake derivedfrom tsunami data[J].Physics of the Earth and PlanetaryInteriors,1982,28(4):320-336.
[29]Ichinose G A,Somerville P,Thio H K,eta l.Rupture process ofthe 1948Fukui earthquake(M 7.1)from the joint inversionof seismic waveform and geodetic data[J].Journal ofGeophysical Research,2005,110:B05301.
[30]Ide S,Takeo M,Yoshida Y.Source process of the 1995Kobeearthquake:Determination of spatio-temporal slipdistribution by Bayesian modeling[J].Bull.Seism.Soc.Am.,1996,86(3):547-566.
[31]Sagiya T,Miyazaki S,Tada T.Continuous GPS array andPresent-day Crustal deformation of Japan[J].Pure andApplied Geophysics,2000,157(11-12):2303-2322.
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