1992年兰德斯地震震源处应力量值的研究
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摘要
给出了根据地震前后应力轴偏转、地震应力降和地震前后相对主应力大小,计算震源处应力量值的方法.并将该方法运用于兰德斯地震的霍姆斯特德谷断层段,获得了该子断层10 km深度处震前最大、中间和最小主应力的量值分别为271,266 MPa和259 MPa;震前断层面上的正应力和剪切应力分别为265 MPa和6.2 MPa;震后断层面上的正应力和剪切应力分别为266 MPa和1.6 MPa.研究结果表明,地震发生后,正压应力增大,有利于破裂的终止;震前剪切应力大于震后剪切应力,且它们的差基本上与应力降大小相近.从研究结果可以看出,虽然地下压应力很大,但是差应力并不大,投影到断层面上的剪切应力也较小.
This study presented a method for estimating stress magnitude in earthquake source region based on rotation of stress axes,seismic stress drop and relative magnitude of principle stresses.We applied this method to the Homestead Valley fault segment of the 1992 Landers earthquake,and obtained the compressive,intermediate and extensional principal stress before the mainshock being 271,266 MPa and 259 MPa,respectively.The pre-seismic normal and shear stress are 265 MPa and 6.2 MPa,respectively.The post-seismic normal and shear stress are 266 MPa and 1.6 MPa,respectively.The result shows that normal stress increase after the mainshock would have benefited to the rupture termination.The pre-seismic shear stress is higher than that of post-seismic one,and their difference corresponds to the stress drop approximately.The estimated underground compressive stress is very large,but the differential stress is small,and the shear-stress projected on to the fault plane is also relatively small.
This study presented a method for estimating stress magnitude in earthquake source region based on rotation of stress axes,seismic stress drop and relative magnitude of principle stresses.We applied this method to the Homestead Valley fault segment of the 1992 Landers earthquake,and obtained the compressive,intermediate and extensional principal stress before the mainshock being 271,266 MPa and 259 MPa,respectively.The pre-seismic normal and shear stress are 265 MPa and 6.2 MPa,respectively.The post-seismic normal and shear stress are 266 MPa and 1.6 MPa,respectively.The result shows that normal stress increase after the mainshock would have benefited to the rupture termination.The pre-seismic shear stress is higher than that of post-seismic one,and their difference corresponds to the stress drop approximately.The estimated underground compressive stress is very large,but the differential stress is small,and the shear-stress projected on to the fault plane is also relatively small.
引文
陈培善,谷继成,李文香.1977.从断裂力学观点研究地震的破裂过程和地震预报[J].地球物理学报,20(3):185--202.
陈培善.1981.分析地震波估算地壳内的应力值[J].地震学报,3(3):251--263.
秦启荣,张烈辉,邓辉,苏培东,王振宇.2004.古构造应力量值确定及其在构造地质建模中的应用[J].岩石力学与工程学报,23(23):3979--3983.
万永革,王敏,沈正康,陈杰,张祖盛,王庆良,甘卫军.2004.利用GPS和水准测量资料反演2001年昆仑山口西8.1级地震的同震滑动分布[J].地震地质,26(3):393--404.
万永革.2006.根据大地震前后应力轴偏转和应力降求取应力量值的研究[J].地震学报,28(5):472--477.
万永革,沈正康,兰从欣.2006.根据走滑大地震前后应力轴偏转和应力降求取偏应力量值的研究[J].地球物理学报,49(3):838--844.
万永革,沈正康,刁桂苓,王福昌,胡新亮,盛书中.2008.利用小震分布和区域应力场确定大震断层面参数方法及其在唐山地震序列中的应用[J].地球物理学报,51(3):793--804.
谢富仁,李宏.1995.利用断层滑动资料确定鲜水河断裂带构造应力方向和大小[J].地震学报,17(2):164--171.
赵建涛,崔效锋,谢富仁.2002.唐山地震震源区构造应力场强度的初步分析[J].地震学报,24(3):268--276.
Fialko Y,Rivera L,Kanamori H.2005.Estimate of differential stress in the upper crust fromvariations in topographyand strike along the San Andreas fault[J].Geophys J Int,160(2):527--532.
Gephart J W,Forsyth D W.1984.Animproved methodfor determining the regional stress tensor using earthquake focalmechanismdata:Application to the San Fernando earthquake sequencec[J].J Geophys Res,89(B11):9305--9320.
Govers R,Wortel J R,Cloetingh S A,Cloetingh P L,Stein C A.1992.Stress magnitude estimates fromearthquakes inoceanic plate interiors[J].J Geophys Res,97(B8):11749--11759.
Guatteri M,Spudich P.1998.Coseismic temporal changes of slip direction:The effect of absolute stress on dynamic rup-ture[J].Bull Seism Soc Amer,88(3):777--789.
Hacker B R,Yin A,Christie J M,Davis G A.1992.Stress magnitude,strain rate and rheology of extended middle conti-nental crust inferred from Quartz grain sizes in the Whipple mountains,California[J].Tectonics,11(1):36--46.
Hauksson E.1994.State of stress fromfocal mechanisms before and after the1992Landers earthquake sequence[J].Bull Seism Soc Amer,84(3):917--934.
Hauksson E.2000.Crustal structure and seismicity distribution adjacent to the Pacific and North America plate boundaryin southern California[J].J Geophys Res,105:13875--13903.
Hsu YJ,Rivera L,Wu Y M,Chang C H,Kanamori H.2010.Spatial heterogeneity of tectonic stress andfrictioninthecrust:Newevidence fromearthquake focal mechanisms in Tai wan[J].Geophys J Int,182(1):329--342.
Jackson D D.1979.The use of a priori data to resolve the non-uniqueness inlinear inversion[J].Geophys J Rastr Soc,57(1):137--157.
Jackson D D,Matsu'ura M.1985.A Bayesian approach to nonlinear inversion[J].J Geophys Res,90(1):581--591.
Knopoff L.1958.Energy release in earthquakes[J].Geophys J R astr Soc,1(1):44--51.
Plenefisch T,Bonjer KP.1997.The stress fieldinthe Rhine Graben areainferredfromearthquake focal mechanisms andestimation of frictional parameters[J].Tectonophysics,275(1--3):71--97.
Shen Z K,Ge X B,Jackson D D,Potter D,Cline M,Sung L Y.1996.Northridge earthquake rupture model based onGlobal Positioning System measurements[J].Bull Seism Soc Amer,86(1B):S37--S48.
Spudich P.1992.On the inference of absolute stress levels fromseismic radiation[J].Tectonophysics,211(1--4):99--106.
Spudich P,Guatteri M,Otsuki K,Minagawa J.1998.Use of fault striations and dislocation models to infer tectonicshear stress during the1995Hyogo-ken Nanbu(Kobe)earthquake[J].Bull Seism Amer Soc,88(2):413--427.
Tanaka H,Chen W M,Wang C Y,Ma K F,Urata N,Mori J,Ando M.2006.Frictional heat fromfaulting of the1999Chi-Chi,Tai wan earthquake[J].Geophys Res Lett,33,10.1029/2006GL026673.
Wald DJ,Heaton T H.1994.Spatial and temporal distribution of slip for the1992Landers,California earthquake[J].Bull Seism Soc Amer,84(3):668--691.
Wesson R L,Boyd O S.2007.Stress before and after the2002Denali fault earthquake[J].Geophys Res Lett,34:L07303,doi:10.1029/2007GL029189.
Wyss M,Gillard D,Liang B.1992.An estimate of the absolute stress tensor in Kaoiki,Hawaii[J].J Geophys Res,97(B4):4763--4768.
Zoback ML.1992.First-and second-order patterns of stressinthelithosphere:The world stress map project[J].J Geo-phy Res,97(B8):11703--11728.
陈培善.1981.分析地震波估算地壳内的应力值[J].地震学报,3(3):251--263.
秦启荣,张烈辉,邓辉,苏培东,王振宇.2004.古构造应力量值确定及其在构造地质建模中的应用[J].岩石力学与工程学报,23(23):3979--3983.
万永革,王敏,沈正康,陈杰,张祖盛,王庆良,甘卫军.2004.利用GPS和水准测量资料反演2001年昆仑山口西8.1级地震的同震滑动分布[J].地震地质,26(3):393--404.
万永革.2006.根据大地震前后应力轴偏转和应力降求取应力量值的研究[J].地震学报,28(5):472--477.
万永革,沈正康,兰从欣.2006.根据走滑大地震前后应力轴偏转和应力降求取偏应力量值的研究[J].地球物理学报,49(3):838--844.
万永革,沈正康,刁桂苓,王福昌,胡新亮,盛书中.2008.利用小震分布和区域应力场确定大震断层面参数方法及其在唐山地震序列中的应用[J].地球物理学报,51(3):793--804.
谢富仁,李宏.1995.利用断层滑动资料确定鲜水河断裂带构造应力方向和大小[J].地震学报,17(2):164--171.
赵建涛,崔效锋,谢富仁.2002.唐山地震震源区构造应力场强度的初步分析[J].地震学报,24(3):268--276.
Fialko Y,Rivera L,Kanamori H.2005.Estimate of differential stress in the upper crust fromvariations in topographyand strike along the San Andreas fault[J].Geophys J Int,160(2):527--532.
Gephart J W,Forsyth D W.1984.Animproved methodfor determining the regional stress tensor using earthquake focalmechanismdata:Application to the San Fernando earthquake sequencec[J].J Geophys Res,89(B11):9305--9320.
Govers R,Wortel J R,Cloetingh S A,Cloetingh P L,Stein C A.1992.Stress magnitude estimates fromearthquakes inoceanic plate interiors[J].J Geophys Res,97(B8):11749--11759.
Guatteri M,Spudich P.1998.Coseismic temporal changes of slip direction:The effect of absolute stress on dynamic rup-ture[J].Bull Seism Soc Amer,88(3):777--789.
Hacker B R,Yin A,Christie J M,Davis G A.1992.Stress magnitude,strain rate and rheology of extended middle conti-nental crust inferred from Quartz grain sizes in the Whipple mountains,California[J].Tectonics,11(1):36--46.
Hauksson E.1994.State of stress fromfocal mechanisms before and after the1992Landers earthquake sequence[J].Bull Seism Soc Amer,84(3):917--934.
Hauksson E.2000.Crustal structure and seismicity distribution adjacent to the Pacific and North America plate boundaryin southern California[J].J Geophys Res,105:13875--13903.
Hsu YJ,Rivera L,Wu Y M,Chang C H,Kanamori H.2010.Spatial heterogeneity of tectonic stress andfrictioninthecrust:Newevidence fromearthquake focal mechanisms in Tai wan[J].Geophys J Int,182(1):329--342.
Jackson D D.1979.The use of a priori data to resolve the non-uniqueness inlinear inversion[J].Geophys J Rastr Soc,57(1):137--157.
Jackson D D,Matsu'ura M.1985.A Bayesian approach to nonlinear inversion[J].J Geophys Res,90(1):581--591.
Knopoff L.1958.Energy release in earthquakes[J].Geophys J R astr Soc,1(1):44--51.
Plenefisch T,Bonjer KP.1997.The stress fieldinthe Rhine Graben areainferredfromearthquake focal mechanisms andestimation of frictional parameters[J].Tectonophysics,275(1--3):71--97.
Shen Z K,Ge X B,Jackson D D,Potter D,Cline M,Sung L Y.1996.Northridge earthquake rupture model based onGlobal Positioning System measurements[J].Bull Seism Soc Amer,86(1B):S37--S48.
Spudich P.1992.On the inference of absolute stress levels fromseismic radiation[J].Tectonophysics,211(1--4):99--106.
Spudich P,Guatteri M,Otsuki K,Minagawa J.1998.Use of fault striations and dislocation models to infer tectonicshear stress during the1995Hyogo-ken Nanbu(Kobe)earthquake[J].Bull Seism Amer Soc,88(2):413--427.
Tanaka H,Chen W M,Wang C Y,Ma K F,Urata N,Mori J,Ando M.2006.Frictional heat fromfaulting of the1999Chi-Chi,Tai wan earthquake[J].Geophys Res Lett,33,10.1029/2006GL026673.
Wald DJ,Heaton T H.1994.Spatial and temporal distribution of slip for the1992Landers,California earthquake[J].Bull Seism Soc Amer,84(3):668--691.
Wesson R L,Boyd O S.2007.Stress before and after the2002Denali fault earthquake[J].Geophys Res Lett,34:L07303,doi:10.1029/2007GL029189.
Wyss M,Gillard D,Liang B.1992.An estimate of the absolute stress tensor in Kaoiki,Hawaii[J].J Geophys Res,97(B4):4763--4768.
Zoback ML.1992.First-and second-order patterns of stressinthelithosphere:The world stress map project[J].J Geo-phy Res,97(B8):11703--11728.
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