一组可用于探测亚稳态橄榄石存在情况的震相
|
摘要
基于简化的波速结构,利用二维伪谱法研究了俯冲带不同位置震源激发的地震波的传播特征.发现当俯冲板块中存在6%的低速异常时,直达P波和直达S波之间存在波阵面近平面的易于识别的P-S转换震相.其传播方向不因震源位置偏离低速层的中心而改变.对于低速层的边界存在±2 km的随机起伏、低速层为楔形、周围介质为水平分层模型这三种情况,这组震相仍然清晰可辨.对于150 km长度的橄榄石楔,模拟结果显示仍然能在一定震中距范围内接收到这一震相.因此,可以尝试用这组震相来探测俯冲带亚稳态橄榄石的存在状态.
We employ a 2-D pseudo-spectral code to study the seismic wave propagation in subduction zones,in which the deep earthquakes that generate the seismic waves are located at different places in subduction slabs.A group of easy to detect P-S converted phases with planar wave front emerges between P and S phases when a high wave speed slab has a 6% low velocity rectangular zone in it.The propagation directions of these phases are only related with the wave velocities of the materials located in two sides of the contact interface.It keeps the same when the hypocenter location deviates from the center of the slab.These phases are still very clear when the boundaries of the low velocity zone are uneven,e.g.,with±2 km undulation,when the low velocity zone changes to wedge shaped,when the surrounding mantle has PREM structure.For a 100～200 km long low velocity wedge,these phases are still detectable.So,we suggest people to employ these phases to detect metastable olivine in subduction zones.
We employ a 2-D pseudo-spectral code to study the seismic wave propagation in subduction zones,in which the deep earthquakes that generate the seismic waves are located at different places in subduction slabs.A group of easy to detect P-S converted phases with planar wave front emerges between P and S phases when a high wave speed slab has a 6% low velocity rectangular zone in it.The propagation directions of these phases are only related with the wave velocities of the materials located in two sides of the contact interface.It keeps the same when the hypocenter location deviates from the center of the slab.These phases are still very clear when the boundaries of the low velocity zone are uneven,e.g.,with±2 km undulation,when the low velocity zone changes to wedge shaped,when the surrounding mantle has PREM structure.For a 100～200 km long low velocity wedge,these phases are still detectable.So,we suggest people to employ these phases to detect metastable olivine in subduction zones.
引文
[1]Ringwood A E.Composition and Petrology of the Earth's Mantle.McGraw-Hill,New York,1975.618
[2]Sung C,Burns R G.Kinetics of high-pressure phase transformation:Implications to the evolution of the olivine- spinel transition in the downgoing lithosphere and its consequences on the dynamics of the mantle.Tectonophysics, 1976,31:1～32
[3]Goto K,Suzuki Z,Hamaguchi H.Stress distribution due to olivine-spinel phase transition in descending plate and deep focus earthquakes.J.Geophys.Res.,1987,92:13811～13820
[4]Bina C R.Phase transition buoyancy contributions to stresses in subducting lithosphere.Geophys.Res.Lett.,1996,23: 3563～3566
[5]Bina C R,Stein S,Marton F C,et al.Implications of slab mineralogy for subduction dynamics.Phys.Earth Planet. Interior,2001,127:51～66.
[6]臧绍先．宁杰远．俯冲带的负浮力及其影响因素．地球物理学报，1994，37(2)：174～183 Zang S X,Ning J Y.The negative buoyancy of the subduction zone and its affecting factors.Chinese J. Geophys.(in Chinese),1994,37(3):174～183
[7]臧绍先，宁杰远．亚稳态橄榄石对俯冲带负浮力的影响及其动力学意义．地球物理学报，2001，44(3)：336～345 Zang S X,Ning J Y.Effects of metastable olivine on negative buoyance in subduction zones and their dynamic significance. Chinese J.Geophys.(in Chinese),2001,44(3):336～345
[8]Kirby S H.Localized polymorphic phase transformations in high-pressure faults and applications to the physical mechanism of deep earthquakes.J.Geophys.Res.,1987, 92:13789～13800
[9]GreenⅡH W,Burnley P C.A new self-organizing mechanism for deep-focus earthquakes.Nature,1989,341: 733～737
[10]Kirby S H,Stein S,Okal E A,et al.Metastable mantle phase transformations and deep earthquakes in subducting lithosphere.Rev.Geophys.,1996,34:261～306
[11]Yoshioka S,Daessler R,Yuen D A.Stress fields associated with metastable phase transitions in descending slabs and deep-focus earthquakes.Phys.Earth Planet.Inter.,1997, 104:345～361
[12]Devaux J P,Fleitout L,Schubert G,et al.Stresses in a subducting slab in the presence of a metastable olivine wedge. J.Geophys.Res.,2000,105:13365～13373
[13]刘亚静．叶国扬，毛兴华等．俯冲带深部应力场的二维粘弹性有限元数值模拟．地震学报，2002，24：285～292 Liu Y J,Ye G Y,Map X H,et al.2-D viscoelastic FEM simulation on stress state in the deep part of a subducted slab. Acta Seismologica Sinica(in Chinese),2002,15(3):301～308
[14]毛兴华，刘亚静，叶国扬等．俯冲带深部应力场的二维弹性有限元数值模拟．地震学报，2002，24：277～284 Mao X H,Liu Y J,Ye G Y,et al.2-D elastic FEM simulation on stress state in the deep part of a subducted slab.Acta Seismologica Sinica(in Chinese),2002,15(3): 294～300
[15]Riedel M R,Karato S.Microstructural development during nucleation and growth.Geophys.J.Int.,1996,125:397～414
[16]Riedel M R,Karato S.Grain-size evolution in subducted oceanic lithosphere associated with the olivine-spinel transformation and its effects on rheology.Earth Planet. Sci.Lett.,1997,145:27～43
[17]Karato S,Riedel M R,Yuen D A.Rheological structure and deformation of subducted slabs in the mantle transition zone: implications for mantle circulation and deep earthquakes. Phys.Earth Planet.Inter.,2001,127:83～108
[18]臧绍先，宁杰远，景志成．俯冲带流变性质的研究．中国科学(D),2001,31(12):705～711 Zang S X,Ning J Y,Jing Z C.Study on the rheology of subducting slabs.Science in China(D),2001,44(12):1119～1127
[19]王曙光，叶国扬，宁杰远等．对一类相变体积分数计算公式的修正．地球物理学报，2007，50(6)：1794～1801 Wang S G,Ye G Y,Ning J Y,et al.Modification of the volume fraction formulae for a sort of phase transformations. Chinese J.Geophys.(in Chinese),2007,50(6):1794～1801
[20]Solomon S C,U K T P.Elevation of the olivine-spinel transition in subducted lithosphere:Seismic evidence.Phys. Earth Planet.Inter.,1975,11:97～108
[21]Roecker S W.Velocity structure in the Izu-Bonin seismic zone and the depth of the olivine-spinel phase transition in the slab.J.Geophys.Res.,1985,90:7771～7794
[22]Collier J,Helffrich G.Topography of the“410”and“660”km seismic discontinuities in the Izu-Bonin subduction zone. Geophys.Res.Lett.,1997,24:1535～1538
[23]Flanagan M P,Shearer P M.Global mapping of topography on transition zone velocity discontinuities by stacking SS precursors.J.Geophys.Res.,1998,103:2673～2692
[24]Iidaka T,Suetsugu D.Seismological evidence for metastable olivine inside a subducting slab.Nature,1992,356:593～595
[25]Chen W P,Brudzinski M R.Seismic anisotropy in the mantle transition zone beneath Fiji-Tonga.Geophys.Res.Lett, 2003,30(13):82,doi:10.1029/2002GL016330
[26]Sekiguchi S.Amplitude distribution of seismic waves for laterally heterogeneous structures including a subducting slab.Geophys.J.Int.,1992,111:448～464
[27]Koper K D,Wiens D A.The waveguide effect of metastable olivine in slabs.Geophys.Res.Lett.,2000,27(4):581～584,doi:10.1029/1999GL011007
[28]Yoshioka S,Murakami T.The effects of metastable olivine wedge in subducted slabs on theoretical seismic waveforms of deep earthquakes.J.Geophys.Res.,2002,107(B12): 2365,doi:10.1029/2001JB001223
[29]Kosloff D,Baysal E.Forward modeling by a Fourier method.Geophysics,1982,47:1402～1412
[30]Kosloff D,Reshef M,Lowenthal D.Elastic wave calculations by the Fourier method.Bulletin of the Seismological Society of America,1984,74:875～891
[31]Fornberg B.The pseudospectral method:comparisons with finite-differences for the elastic wave equations.Geophysics, 1987,52:483～501
[32]Fornberg B.The pseudospectral method:accurate representation of interfaces in elastic wave calculations. Geophysics,1988,53:625～637
[33]Wang Y B,Takenaka H,Furumura T.Modeling seismic wave propagation in a two-dimensional cylindrical whole-earth model using the pseudospectral method.Geophys.J.Int, 2001,145:689～708
[34]赵志新，徐纪人．堀内茂木．错格实数傅里叶变换微分算子及其在非均匀介质波动传播中的应用．地球物理学报，2003，46(2)：234～240 Zhao Z X,Xu J R,Horiuchi S.Staggered grid real value FFT differentiation operator and its application on wave propagation simulation in the heterogeneous medium.Chinese J.Geophys.(in Chinese),2003,46(2):234～240
[35]谢桂生，刘洪，赵连功．伪谱法地震波正演模拟的多线程并行计算．地球物理学进展，2005，20(1)：17～23 Xie G S,Liu H,Zhao L G.Parallel algorithm based on the multithread technique for pseudospectal modeling of seismic wave.Progress in Geophysics(in Chinese),2005,20(1): 17～23
[36]Fornberg B.High-order finite differences and the pseudospectral method on staggered grids.SIAMJ.Numer. Anal.,1990,27:904～918
[37]Furumura T,Takenaka H.A stable method for numerical differentiation of data with discontinuities at end-points by means of fourier transform-symmetric differentiation. Geophys.Expl.,1992,45:303～309
[38]Martin S,Rietbrock A,Haberland C,et al.Guided waves propagating in subducted oceanic crust.J.Geophys.Res., 2003,108(B11):2536,doi:10.1029/2003JB002450
[2]Sung C,Burns R G.Kinetics of high-pressure phase transformation:Implications to the evolution of the olivine- spinel transition in the downgoing lithosphere and its consequences on the dynamics of the mantle.Tectonophysics, 1976,31:1～32
[3]Goto K,Suzuki Z,Hamaguchi H.Stress distribution due to olivine-spinel phase transition in descending plate and deep focus earthquakes.J.Geophys.Res.,1987,92:13811～13820
[4]Bina C R.Phase transition buoyancy contributions to stresses in subducting lithosphere.Geophys.Res.Lett.,1996,23: 3563～3566
[5]Bina C R,Stein S,Marton F C,et al.Implications of slab mineralogy for subduction dynamics.Phys.Earth Planet. Interior,2001,127:51～66.
[6]臧绍先．宁杰远．俯冲带的负浮力及其影响因素．地球物理学报，1994，37(2)：174～183 Zang S X,Ning J Y.The negative buoyancy of the subduction zone and its affecting factors.Chinese J. Geophys.(in Chinese),1994,37(3):174～183
[7]臧绍先，宁杰远．亚稳态橄榄石对俯冲带负浮力的影响及其动力学意义．地球物理学报，2001，44(3)：336～345 Zang S X,Ning J Y.Effects of metastable olivine on negative buoyance in subduction zones and their dynamic significance. Chinese J.Geophys.(in Chinese),2001,44(3):336～345
[8]Kirby S H.Localized polymorphic phase transformations in high-pressure faults and applications to the physical mechanism of deep earthquakes.J.Geophys.Res.,1987, 92:13789～13800
[9]GreenⅡH W,Burnley P C.A new self-organizing mechanism for deep-focus earthquakes.Nature,1989,341: 733～737
[10]Kirby S H,Stein S,Okal E A,et al.Metastable mantle phase transformations and deep earthquakes in subducting lithosphere.Rev.Geophys.,1996,34:261～306
[11]Yoshioka S,Daessler R,Yuen D A.Stress fields associated with metastable phase transitions in descending slabs and deep-focus earthquakes.Phys.Earth Planet.Inter.,1997, 104:345～361
[12]Devaux J P,Fleitout L,Schubert G,et al.Stresses in a subducting slab in the presence of a metastable olivine wedge. J.Geophys.Res.,2000,105:13365～13373
[13]刘亚静．叶国扬，毛兴华等．俯冲带深部应力场的二维粘弹性有限元数值模拟．地震学报，2002，24：285～292 Liu Y J,Ye G Y,Map X H,et al.2-D viscoelastic FEM simulation on stress state in the deep part of a subducted slab. Acta Seismologica Sinica(in Chinese),2002,15(3):301～308
[14]毛兴华，刘亚静，叶国扬等．俯冲带深部应力场的二维弹性有限元数值模拟．地震学报，2002，24：277～284 Mao X H,Liu Y J,Ye G Y,et al.2-D elastic FEM simulation on stress state in the deep part of a subducted slab.Acta Seismologica Sinica(in Chinese),2002,15(3): 294～300
[15]Riedel M R,Karato S.Microstructural development during nucleation and growth.Geophys.J.Int.,1996,125:397～414
[16]Riedel M R,Karato S.Grain-size evolution in subducted oceanic lithosphere associated with the olivine-spinel transformation and its effects on rheology.Earth Planet. Sci.Lett.,1997,145:27～43
[17]Karato S,Riedel M R,Yuen D A.Rheological structure and deformation of subducted slabs in the mantle transition zone: implications for mantle circulation and deep earthquakes. Phys.Earth Planet.Inter.,2001,127:83～108
[18]臧绍先，宁杰远，景志成．俯冲带流变性质的研究．中国科学(D),2001,31(12):705～711 Zang S X,Ning J Y,Jing Z C.Study on the rheology of subducting slabs.Science in China(D),2001,44(12):1119～1127
[19]王曙光，叶国扬，宁杰远等．对一类相变体积分数计算公式的修正．地球物理学报，2007，50(6)：1794～1801 Wang S G,Ye G Y,Ning J Y,et al.Modification of the volume fraction formulae for a sort of phase transformations. Chinese J.Geophys.(in Chinese),2007,50(6):1794～1801
[20]Solomon S C,U K T P.Elevation of the olivine-spinel transition in subducted lithosphere:Seismic evidence.Phys. Earth Planet.Inter.,1975,11:97～108
[21]Roecker S W.Velocity structure in the Izu-Bonin seismic zone and the depth of the olivine-spinel phase transition in the slab.J.Geophys.Res.,1985,90:7771～7794
[22]Collier J,Helffrich G.Topography of the“410”and“660”km seismic discontinuities in the Izu-Bonin subduction zone. Geophys.Res.Lett.,1997,24:1535～1538
[23]Flanagan M P,Shearer P M.Global mapping of topography on transition zone velocity discontinuities by stacking SS precursors.J.Geophys.Res.,1998,103:2673～2692
[24]Iidaka T,Suetsugu D.Seismological evidence for metastable olivine inside a subducting slab.Nature,1992,356:593～595
[25]Chen W P,Brudzinski M R.Seismic anisotropy in the mantle transition zone beneath Fiji-Tonga.Geophys.Res.Lett, 2003,30(13):82,doi:10.1029/2002GL016330
[26]Sekiguchi S.Amplitude distribution of seismic waves for laterally heterogeneous structures including a subducting slab.Geophys.J.Int.,1992,111:448～464
[27]Koper K D,Wiens D A.The waveguide effect of metastable olivine in slabs.Geophys.Res.Lett.,2000,27(4):581～584,doi:10.1029/1999GL011007
[28]Yoshioka S,Murakami T.The effects of metastable olivine wedge in subducted slabs on theoretical seismic waveforms of deep earthquakes.J.Geophys.Res.,2002,107(B12): 2365,doi:10.1029/2001JB001223
[29]Kosloff D,Baysal E.Forward modeling by a Fourier method.Geophysics,1982,47:1402～1412
[30]Kosloff D,Reshef M,Lowenthal D.Elastic wave calculations by the Fourier method.Bulletin of the Seismological Society of America,1984,74:875～891
[31]Fornberg B.The pseudospectral method:comparisons with finite-differences for the elastic wave equations.Geophysics, 1987,52:483～501
[32]Fornberg B.The pseudospectral method:accurate representation of interfaces in elastic wave calculations. Geophysics,1988,53:625～637
[33]Wang Y B,Takenaka H,Furumura T.Modeling seismic wave propagation in a two-dimensional cylindrical whole-earth model using the pseudospectral method.Geophys.J.Int, 2001,145:689～708
[34]赵志新，徐纪人．堀内茂木．错格实数傅里叶变换微分算子及其在非均匀介质波动传播中的应用．地球物理学报，2003，46(2)：234～240 Zhao Z X,Xu J R,Horiuchi S.Staggered grid real value FFT differentiation operator and its application on wave propagation simulation in the heterogeneous medium.Chinese J.Geophys.(in Chinese),2003,46(2):234～240
[35]谢桂生，刘洪，赵连功．伪谱法地震波正演模拟的多线程并行计算．地球物理学进展，2005，20(1)：17～23 Xie G S,Liu H,Zhao L G.Parallel algorithm based on the multithread technique for pseudospectal modeling of seismic wave.Progress in Geophysics(in Chinese),2005,20(1): 17～23
[36]Fornberg B.High-order finite differences and the pseudospectral method on staggered grids.SIAMJ.Numer. Anal.,1990,27:904～918
[37]Furumura T,Takenaka H.A stable method for numerical differentiation of data with discontinuities at end-points by means of fourier transform-symmetric differentiation. Geophys.Expl.,1992,45:303～309
[38]Martin S,Rietbrock A,Haberland C,et al.Guided waves propagating in subducted oceanic crust.J.Geophys.Res., 2003,108(B11):2536,doi:10.1029/2003JB002450
版权所有：© 2023 中国地质图书馆 中国地质调查局地学文献中心