日本俯冲带地震发生过程的数值模拟研究
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摘要
了解地震发生的动力学机制是研究地震发震原因的关键,而数值模拟的方法是高速、有效的手段.2011年3月11日日本东北部宫城县发生9.0级大地震,文中以该次大地震所在的日本俯冲带为研究对象,通过使用黏弹性有限元数值模拟,并引用接触对,建立了研究区二维数值模型,模拟俯冲带与上覆板片之间的滑动、黏滞到再滑动的过程,亦即断层失稳发生地震的过程.模拟结果显示,随着太平洋板块不断俯冲,在俯冲带上自发出现了断层闭锁、解锁到再闭锁的黏滑过程,且这种过程呈现一定的准周期性,大事件主要集中分布在20～30km的深度范围内.根据俯冲带可能在俯冲过程中角度的变化,建立了不同的模型,进行模拟对比研究,结果表明,俯冲带的几何形态,以及俯冲角度变化所在的不同深度,对模拟的结果有不同的影响.
Understanding of earthquake dynamic mechanism is the key of studying the causes of earthquakes,especially the large events.Numerical simulation is a fast and efficient approach to solve this issue.The Mw9.0 earthquake of Miyagi Prefecture,northeastern Japan on 11th March,2011 occurred at the Japan subduction slab.In this article,we take the Japan subduction slab as the study object,and simulate the stick-slip process between the slab and overlying plate as well as the instability processes of the fault by a two-dimensional viscoelastic finite element model.The results show that the underthrusting of the Pacific plate leads to the spontaneous stick-slip processes,characterized by fault locking,fault unlocking and back to fault locking again,which present certain quasi-periodicity in the slab,and big events mainly concentrated in the depth range of 20~30 km.Using different models with varied dip angles of the subduction slab,we make a comparative study of simulations.The results reveal that the geometry of the subduction slab and different depths where the subduction angle changes have different effects on the simulation results.
Understanding of earthquake dynamic mechanism is the key of studying the causes of earthquakes,especially the large events.Numerical simulation is a fast and efficient approach to solve this issue.The Mw9.0 earthquake of Miyagi Prefecture,northeastern Japan on 11th March,2011 occurred at the Japan subduction slab.In this article,we take the Japan subduction slab as the study object,and simulate the stick-slip process between the slab and overlying plate as well as the instability processes of the fault by a two-dimensional viscoelastic finite element model.The results show that the underthrusting of the Pacific plate leads to the spontaneous stick-slip processes,characterized by fault locking,fault unlocking and back to fault locking again,which present certain quasi-periodicity in the slab,and big events mainly concentrated in the depth range of 20~30 km.Using different models with varied dip angles of the subduction slab,we make a comparative study of simulations.The results reveal that the geometry of the subduction slab and different depths where the subduction angle changes have different effects on the simulation results.
引文
[1]温瑞智,任叶飞,李小军.日本Mw9.0级地震海啸数值模拟与启示.国际地震动态,2011,(4):22-27.Wen R Z,Ren Y F,Li X J.The tsunami simulation for offthe Pacific coast of Tohoku earthquake and disaster mitigationin China.Recent Developments in World Seismology(inChinese),2011,(4):22-27.
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[7]Kelin W L,Yan H,He J H.Deformation cycles ofsubduction earthquakes in a viscoelastic Earth.Nature,2012,484(7394):327-332.
[8]Fukao Y,Obayashi M,Nakakuki T,et al.Stagnant slab:Areview.Annu Rev Earth Planet Sci,2009,37(1):19-46.
[9]DeMets C,Gorden R G,Argus D F,et al.Current platemotions.Geophys.J.Int.,1990,101(2):425-478.
[10]Yoshi T.A detailed cross-section of the deep seismic zonebeneath northeastern Honshu,Japan.Tectonophysics,1979,55(3-4):349-360.
[11]Yoshioka S,Loo H Y,Mikumo T,et al.A model of post-seismic recovery induced by a deep-focus earthquake.Physicsof the Earth and Planetary Interiors,1992,72(1-2):83-98.
[12]Huang Z C,Zhao D P,Wang L S.Shear wave anisotropy inthe crust,mantle wedge,and subducting Pacific slab undernortheast Japan.Geochem.,Geophy.Geosyst.,2011,12(1):Q01002,doi:10.1029/2010GC003343.
[13]Loo H Y,Gao X L,Sun J X,et al.Three-dimensionalnumerical modeling of earthquake migration along anorthwestern Pacific subduction slab.Geophys.Res.Lett.,1992,19(3):313-316.
[14]张建,汪集旸.南海北部陆缘带构造扩张的深部地球动力学特征.中国科学D辑,2000,30(6):561-567.Zhang J,Wang J Y.Geodynamic characteristics of tectonicextension in the northern margin of South China Sea.Sciencein China(Series D),2001,44(5):437-445.
[15]臧绍先,宁杰远,景志成.俯冲带流变性质的研究.中国科学D辑,2001,31(9):705-711.Zang S X,Ning J Y,Jing Z C.Study on the rheology ofsubducting slabs.Science in China(Series D),2001,44(12):1119-1127.
[16]Zhao D P.Global tomographic images of mantle plumes andsubducting slabs:insight into deep Earth dynamics.Phys.Earth.Planet.Inter.,2004,146(1-2):3-34.
[17]Zhu G Z,Shi Y L,Tackley P.Subduction of the WesternPacific Plate underneath Northeast China:Implications ofnumerical studies.Physics of the Earth and PlanetaryInteriors,2010,178(1-2):92-99.
[18]朱守彪,张培震.2008年汶川Ms8.0地震发生过程的动力学机制研究.地球物理学报,2009,52(2):418-427.Zhu S B,Zhang P Z.A study on the dynamical mechanismsof the Wenchuan Ms8.0earthquake,2008.Chinese J.Geophys.(in Chinese),2009,52(2):418-427.
[19]朱守彪,邢会林,谢富仁等.地震发生过程的有限单元法模拟——以苏门答腊俯冲带上的大地震为例.地球物理学报,2008,51(2):460-468.Zhu S B,Xing H L,Xie F R,et al.Simulation of earthquakeprocesses by finite element method:The case of megathrustearthquakes on the Sumatra subduction zone.Chinese J.Geophys.(in Chinese),2008,51(2):460-468.
[20]石耀霖,王其允.斜俯冲板块边界变形分配的力学分析.地球物理学报,1994,37(5):606-612.Shi Y L,Wang Q Y.Mechanics of deformation partitioningat plate boundaries of oblique subduction.Chinese J.Geophys.(in Chinese),1994,37(5):606-612.
[21]李大鹏,陈岳龙,靳野.板块俯冲带研究中的数值实验.地球科学进展,2010,25(6):582-596.Li D P,Chen Y L,Jin Y.Numerical simulation in subductionzone study.Advances in Earth Science(in Chinese),2010,25(6):582-596.
[22]Gorczy W,Willner A P,Gerya T V,et al.Physical controlsof magmatic productivity at Pacific-type convergent margins:Numerical modelling.Physics of the Earth and PlanetaryInteriors,2007,163(1):209-232.
[23]Hall C E,Gurnis M,Sdrolias M,et al.Catastrophicinitiation of subduction following forced convergence acrossfracture zones.Earth and Planetary Science Letters,2003,212(1-2):15-30.
[24]Hassani R,Jongmans D,Chery J.Study of plate deformationand stress in subduction processes using two-dimensionalnumerical models.Journal of Geophysical Research,1997,102(B8):17951-17965.
[25]Sobolev S V,Babey A Y.What drives orogeny in the Andes?Geology,2005,33(8):617-620.
[26]Tagawa M,Nakakuki T,Kameyama M,et al.The role ofhistory-dependent rheology in plate boundary lubrication forgenerating one-sided subduction.Pure and Applied Geophysics,2007,164(5):879-907.
[2]Ozawa S,Nishimura T,Suito H,et al.Coseismic andpostseismic slip of the 2011 magnitude-9 Tohoku-Okiearthquake.Nature,2011,475(7356):373-376,doi:10.1038/nature10227.
[3]Kerr R A.A tantalizing view of what set off Japan′s killerquake.Science,2012,335(6066):272,doi:10.1126/science.335.6066.272.
[4]Kato A,Obara K,Lgarashi T,et al.Propagation of slowslip leading up to the 2011 Mw9.0Tohoku-Oki earthquake.Science,2012,335(6069):705-708.
[5]徐彦.2011年日本9.0级及7.5级地震震源破裂反投影初步结果.国际地震动态,2011,(4):34-37,5.Xu Y.Back projection results of the 2011Japan Mw9.0andM7.5earthquakes.Recent Developments in World Seismology(inChinese),2011,(4):34-37,5.
[6]Shinzaburo O,Takuya N,Hisashi S,et al.Coseismic andpostseismic slip of the 2011 magnitude-9 Tohoku-Okiearthquake.Nature,2011,475:373-376.
[7]Kelin W L,Yan H,He J H.Deformation cycles ofsubduction earthquakes in a viscoelastic Earth.Nature,2012,484(7394):327-332.
[8]Fukao Y,Obayashi M,Nakakuki T,et al.Stagnant slab:Areview.Annu Rev Earth Planet Sci,2009,37(1):19-46.
[9]DeMets C,Gorden R G,Argus D F,et al.Current platemotions.Geophys.J.Int.,1990,101(2):425-478.
[10]Yoshi T.A detailed cross-section of the deep seismic zonebeneath northeastern Honshu,Japan.Tectonophysics,1979,55(3-4):349-360.
[11]Yoshioka S,Loo H Y,Mikumo T,et al.A model of post-seismic recovery induced by a deep-focus earthquake.Physicsof the Earth and Planetary Interiors,1992,72(1-2):83-98.
[12]Huang Z C,Zhao D P,Wang L S.Shear wave anisotropy inthe crust,mantle wedge,and subducting Pacific slab undernortheast Japan.Geochem.,Geophy.Geosyst.,2011,12(1):Q01002,doi:10.1029/2010GC003343.
[13]Loo H Y,Gao X L,Sun J X,et al.Three-dimensionalnumerical modeling of earthquake migration along anorthwestern Pacific subduction slab.Geophys.Res.Lett.,1992,19(3):313-316.
[14]张建,汪集旸.南海北部陆缘带构造扩张的深部地球动力学特征.中国科学D辑,2000,30(6):561-567.Zhang J,Wang J Y.Geodynamic characteristics of tectonicextension in the northern margin of South China Sea.Sciencein China(Series D),2001,44(5):437-445.
[15]臧绍先,宁杰远,景志成.俯冲带流变性质的研究.中国科学D辑,2001,31(9):705-711.Zang S X,Ning J Y,Jing Z C.Study on the rheology ofsubducting slabs.Science in China(Series D),2001,44(12):1119-1127.
[16]Zhao D P.Global tomographic images of mantle plumes andsubducting slabs:insight into deep Earth dynamics.Phys.Earth.Planet.Inter.,2004,146(1-2):3-34.
[17]Zhu G Z,Shi Y L,Tackley P.Subduction of the WesternPacific Plate underneath Northeast China:Implications ofnumerical studies.Physics of the Earth and PlanetaryInteriors,2010,178(1-2):92-99.
[18]朱守彪,张培震.2008年汶川Ms8.0地震发生过程的动力学机制研究.地球物理学报,2009,52(2):418-427.Zhu S B,Zhang P Z.A study on the dynamical mechanismsof the Wenchuan Ms8.0earthquake,2008.Chinese J.Geophys.(in Chinese),2009,52(2):418-427.
[19]朱守彪,邢会林,谢富仁等.地震发生过程的有限单元法模拟——以苏门答腊俯冲带上的大地震为例.地球物理学报,2008,51(2):460-468.Zhu S B,Xing H L,Xie F R,et al.Simulation of earthquakeprocesses by finite element method:The case of megathrustearthquakes on the Sumatra subduction zone.Chinese J.Geophys.(in Chinese),2008,51(2):460-468.
[20]石耀霖,王其允.斜俯冲板块边界变形分配的力学分析.地球物理学报,1994,37(5):606-612.Shi Y L,Wang Q Y.Mechanics of deformation partitioningat plate boundaries of oblique subduction.Chinese J.Geophys.(in Chinese),1994,37(5):606-612.
[21]李大鹏,陈岳龙,靳野.板块俯冲带研究中的数值实验.地球科学进展,2010,25(6):582-596.Li D P,Chen Y L,Jin Y.Numerical simulation in subductionzone study.Advances in Earth Science(in Chinese),2010,25(6):582-596.
[22]Gorczy W,Willner A P,Gerya T V,et al.Physical controlsof magmatic productivity at Pacific-type convergent margins:Numerical modelling.Physics of the Earth and PlanetaryInteriors,2007,163(1):209-232.
[23]Hall C E,Gurnis M,Sdrolias M,et al.Catastrophicinitiation of subduction following forced convergence acrossfracture zones.Earth and Planetary Science Letters,2003,212(1-2):15-30.
[24]Hassani R,Jongmans D,Chery J.Study of plate deformationand stress in subduction processes using two-dimensionalnumerical models.Journal of Geophysical Research,1997,102(B8):17951-17965.
[25]Sobolev S V,Babey A Y.What drives orogeny in the Andes?Geology,2005,33(8):617-620.
[26]Tagawa M,Nakakuki T,Kameyama M,et al.The role ofhistory-dependent rheology in plate boundary lubrication forgenerating one-sided subduction.Pure and Applied Geophysics,2007,164(5):879-907.
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