几何弯曲断层活动性的模拟
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摘要
运用有限元法建立大尺度几何弯曲断层(长约750 km)的二维模型,并利用接触单元技术模拟断层间的作用,模拟了几千年时间尺度内走滑断层的活动,探讨了具有一定几何形态断层对断层系统活动的影响.几何弯曲的断层导致了应力的集中,而且在断层的地震事件中起到了抑制作用,但是也为孕育大震提供了条件.和平直断层的模拟结果比较得知,断层的儿何弯曲不仅影响地震破裂长度、改变了地震滑移量,也很大程度影响了能量释放的空间位置,改变了地震轮回周期.此外,弯曲断层应力的不均匀也使主震前往往有前震发生.另外通过模拟可以看出.弯曲断层活动表现出明显的特征地震,使得地震一频次曲线偏离GR公式,说明了对单个断层而言,特征地震可能更能体现断层的地震活动,这对我们进行地震预测和危险性分析有着很重要的参考意义.
Using finite element method (FEM) with contact algorithm, we established a 2D bend fault model and calculated the activities of this fault in thousands of years, and discussed how the geometry bending affects the activities. Due to the effect of geometry bending, stress concentrates on some parts of fault and the distribution of stress on fault is highly heterogeneous. Additionally, geometry bending restrains or stops some ruptures, but can produce strong earthquakes. Compared with planar fault, bend fault can not only affect earthquake ruptures and slip, but also change temporal and spacial evolution of earthquakes. Because of the heterogeneous stress distribution of bend fault, some foreshocks occurred before main shock, but not occurred on planar fault. The earthquake frequency-size distribution of simulation result deviates from the G-R relation, showing that a characteristic model is more reasonable, especially, characteristic slip can be seen from result distinctly.
Using finite element method (FEM) with contact algorithm, we established a 2D bend fault model and calculated the activities of this fault in thousands of years, and discussed how the geometry bending affects the activities. Due to the effect of geometry bending, stress concentrates on some parts of fault and the distribution of stress on fault is highly heterogeneous. Additionally, geometry bending restrains or stops some ruptures, but can produce strong earthquakes. Compared with planar fault, bend fault can not only affect earthquake ruptures and slip, but also change temporal and spacial evolution of earthquakes. Because of the heterogeneous stress distribution of bend fault, some foreshocks occurred before main shock, but not occurred on planar fault. The earthquake frequency-size distribution of simulation result deviates from the G-R relation, showing that a characteristic model is more reasonable, especially, characteristic slip can be seen from result distinctly.
引文
[1] Rice J R. The mechanics of earthquake rupture. In:Physics of the Earth's Interior. Bologna; Italian Physical Society. 1980． 555-549
[2] Ohnake M, Kuwahara Y, Yamamoto K, et al. Dynamic breakdown processes and the generating mechanism for high-frequency elastic radiation during stick-slip instabilities. Geophys/ Monogr. ,1986,6:13-24
[3] Ohnake M. Earthquake source nucleation:a physical model for short-term precursors. Tectonophysics, 1992,211:149-178
[4] Dieterich J H. A model for the nucleation of earthquake slip. Geophys. Monogr. ,1986,6:37-47
[5] Dieterich J H. Earthquake nuclealion on faults with rate-and state-dependent strength. Tectonophysics, 1992, 211:115-134
[6] Kato N,Yamamoto K, Yamamoto H.et al. Strain-rate effect on frictional strength and the slip nucleation process. Tectonophysics, 1992,211:269-282
[7] 何昌荣.断层上的地震成核过程与前兆模拟研究.中国地震,2000,16(1) :1-13 He C R. Numerical simulation of earthquake nucleation and precursory process in slipping fault planes. Earthquake Research in China(in Chinese),2000,16(1) :1-13
[8] 马胜利,刘力强,马瑾等.均匀和非均匀断层滑动失稳成核过程的实验研究.中国科学(D辑),2003,33(S1) :45-52 Ma S L, Liu L Q, Ma J, et al. The laboratory study of the nucleation in homogeneous and heterogeneous slip fault. Science in China (in Chinese) , 2003 ,33(S1) :45-52
[9] 茂水清夫.日本的地震预报.庄灿涛等译.北京:地震出版社,1986 Mogi K. Earthquake Prediction in Japan (in Chinese). Trans, by Zhuang C T, et al. Beijing: Seismological Press. 1986
[10] King G C P. Speculations on the geometry of the initiation and termination process of earthquake rupture and its relation to morphology and geological structure. Pure and Applie Geophysics, 1986 ,124:567-585
[11] Scholz C H. The Mechanics of Earthquakes and Faulting. Cambridge; Cambridge University Press,1990
[12] Sibson R H. Rupture interaction with fault jogs. In; Das S, Boatright J, Scholz eds. Earthquake Source Mechanics. AGU Geophys. Mono. ,1986,37:157-168
[13] 马瑾.构造物理学概论.北京:地震出版社,1987 Ma J. Conspectus of Tectonic Physics (in Chinese). Beijing: Seismological Press, 1987
[14] 马瑾,马胜利,刘力强.断层几何结构与物理场的演化及失稳特征.地震学报,1996,18:200-207 Ma J, Ma S L, Liu L Q. Geometry structure of fault and evolution of physical field and destabilization characteristics. Acta Seismologica Sinica (in Chinese) ,1996,18:200-207
[15] Lei X L, Kusunose K, Satho T, et al. The hierarchical rupture process of a fault: an experimental study. Phys. Earth Planet Inter. ,2003,137:213-228
[16] 马胜利,刘力强,马瑾等.基于实验结果讨论断层破裂与强震物理过程的若干问题.地学前缘,2003,10:225-232 Ma S L, Liu L Q, Ma J, et al. A discussion on related issues of physical process of faulting and strong earthquake based on experimental results. Earth Science Frontiers (in Chinese), 2003,10:225-232
[17] Haskell N A. Total energy and energy spectral density of elastic wave radiation from propagating faults. Bull. Seism. Soc,Am. ,1964,54:1811-1841
[18] Haskell N A. Elastic displacements in the near-field of a propagating fault. Bull. Seism. Soc. Am., 1969,59:865-908
[19] Archuleta R J. A faulting model for the 1979 Imperial Valley earthquake. J. Geophys. Res. ,1984,89:4559-4585
[20] Hartzell S H, Heaton T H. Rupture history of the 1984 Morgan Hill, California, earthquake from the inversion of strong motion records. Bull. Seism. Soc. Am. ,1986,76:649-674
[21] Burridge R. Admissible speeds for plane-strain self-similar shear cracks with friction but lacking cohesion. Geophys. J. R. Astr. Soc. ,1973,35:439-455
[22] Andrews D J. Rupture velocity of plane strain shear cracks. J. Geophys. Res. ,1976,81(32) :5679-5687
[23] Madariaga R. Dynamics of an expanding circular fault. Bull. Seism. Soc. Am. ,1976,66:639-666
[24] Archuleta R J. Experimental and numerical three-dimensional simulations of strike-slip earthquakes [Ph. D. thesis]. San Diego: University of California, 1984
[25] Day S M. Three-dimensional simulation of spontaneous rupture: the effect of nonuniform prestress. Bull. Seism. Soc. Am. , 1982,72:1881-1902
[26] Hill D P, Reasenberg P A, Michael A, et al. Seismicity remotely triggered by the magnitude 7． 3 Landers, California, earthquake. Science, 1993 ,260:1617-1623
[27] Anderson J G, Brune J N, Louie J N,et al. Seismicity in the western Great Basin apparently triggered by the Landers, California, earthquake, 28 June 1992． Bull. Seism. Soc. Am. ,1994,84:863-891
[28] Bodin P, Gomberg J. Triggered seismicity and deformation between the Landers, California, and Little Skull mountain, Nevada earthquakes. Bull. Seism. Soc. Am. , 1994,84:855-843
[29] Beeler N M, Tullis T E. Self-healing slip pulses in dynamic rupture models due to velocity-dependent strength. Bull. Seism. Soc. Am. ,1996,86:1130-1148
[30] Ruina A . Slip instability and state variable friction laws. J. Geophys. Res. ,1983,88:10359-10370
[31] Oglesby D D, Day S M. Fault geometry and the dynamics of the 1999 Chi Chi (Taiwan) Earthquake. Bull. Seism. Soc. Am. ,2001,91:1099-1111
[32] Harris R A. Numerical simulations of large earthquakes:dynamic rupture propagation on heterogeneous faults. Pure and Applied Geophysics , 2004,161:2171-2181
[33] Harsha S B, Marion O, Renata D, et al. Role of fault branches in earthquake rupture dynamics. J. Geophys. Res. ,2007,112:B11309
[34] Sonia F, Harsha S B, Renata D, et al. Fault branching and rupture directivity. J. Geophys. Res. ,2005,110:B06312
[35] Stefan B, Carlson J M. Influence of friction and fault geometry on earthquake rupture. J. Geophys. Res. ,2000, 105:6069-6088
[36] Shiann J L. Kuo F M, How-Wei Chen. Effects of fault geometry and slip style on near-fault static displacements caused by the 1999 Chi-Chi. Taiwan Earthquake ,2006,241:336-350
[37] Li Q, Liu M. Geometrical impact of the San Andreas Fault on stress and seismicity in California. Geophys. Res. Lett. , 2006,33:L08302
[38] Qing S L, Mian L. Initiation of the San Jacinto Fault and its interaction with the San Andreas Fault: insights from geodynamic modeling. Pure and Applied Geophysics ,2007,164:1937-1945
[39] Oglesby D D. Earthquake dynamics on dip-slip faults [Ph. D. thesis]. Santa Barbara: University of California, 1999
[40] Andrews D J. Rupture propagation with finite stress in antiplane strain. J. Geophys. Res. ,1976,81:3575-3582
[41] Matsu'ura M, Kataoka H, Shibazaki B. Slip-dependence friction law and nucleation processes in earthquake rupture. Tectonophysics, 1992,211:135-148
[42] Dieterich J H. Modeling of rock friction 1． Experiment results and constitutive equations. J. Geophys. Res. ,1979,84:2161-2168
[43] Ruina A L. Slip instability and state variable friction laws. J. Geophys. Res. ,1983,88:10359-10370
[44] Dieterich J H. Time-dependence friction as a possible mechanism for aftershocks. J. Geophys. Res. , 1972, 77:3771-3781
[45] 马宗晋,张德成.板块构造活动与地震.见:板块构造基本问题.北京:地震出版社,1986． 363-391 Ma Z J, Zhang D C. The activity of plate and earthquakes (in Chinese). In: The Principle Problems in Plate Structure. Beijing:Seismological Press,1986． 363-391
[46] King G, Nabelek J. Role of fault bends in the initiation and termination of earthquake rupture. Science, 1985,228:984-987
[47] Sibson R H. Stopping of earthquake ruptures at dilational fault jogs. Nature, 1985 ,316:248-251
[48] Wesnousky S G. Seismological and structural evolution of strike slip faults. Nature, 1988,335:340-343
[49] Sieh K. The repetition of large-earthquake ruptures. Proc.Nad. Acad. Sci. USA ,1996,93:3764-3771
[50] 陆远忠.地震预报的地震学方法.北京:地震出版社,1985 Lu Y Z. Seismological Method of Earthquake Prediction (in Chinese). Beijing: Seismological Press, 1985
[51] Schwartz D P, Coppersmith K J. Fault behavior and characteristic earthquakes:examples from the Wasatch and San Andreas Fault zones. J. Geophys. Res. ,1984,89:5981-5998
[52] Aki K. Asperities, barriers, characteristic earthquakes and strong motion prediction. J. Geophys. Res. , 1984,89:5867-5872
[53] Bak P, Tang C. Earthquakes as a self-organized critical phenomenon. J. Geophys. Res. ,1989,94:15635-15637
[54] 李全林等.地震频度-震级关系的时空扫描.北京:地震出版社,1979 Li Q L et al. Time-Space Scanning of Seismic Frequency-Magnitude Relation (in Chinese). Beijing: Seismological Press, 1979
[55] 孙文富,顾浩鼎.具有独立过程的地震序列震级-频度分布.地震学报,1992,(3) :273-280 Sun W F, Gu H D. The seismic frequency-magnitude distribution of independent process. Acta Seismologica Sinica (in Chinese), 1992, (3) :273-280
[2] Ohnake M, Kuwahara Y, Yamamoto K, et al. Dynamic breakdown processes and the generating mechanism for high-frequency elastic radiation during stick-slip instabilities. Geophys/ Monogr. ,1986,6:13-24
[3] Ohnake M. Earthquake source nucleation:a physical model for short-term precursors. Tectonophysics, 1992,211:149-178
[4] Dieterich J H. A model for the nucleation of earthquake slip. Geophys. Monogr. ,1986,6:37-47
[5] Dieterich J H. Earthquake nuclealion on faults with rate-and state-dependent strength. Tectonophysics, 1992, 211:115-134
[6] Kato N,Yamamoto K, Yamamoto H.et al. Strain-rate effect on frictional strength and the slip nucleation process. Tectonophysics, 1992,211:269-282
[7] 何昌荣.断层上的地震成核过程与前兆模拟研究.中国地震,2000,16(1) :1-13 He C R. Numerical simulation of earthquake nucleation and precursory process in slipping fault planes. Earthquake Research in China(in Chinese),2000,16(1) :1-13
[8] 马胜利,刘力强,马瑾等.均匀和非均匀断层滑动失稳成核过程的实验研究.中国科学(D辑),2003,33(S1) :45-52 Ma S L, Liu L Q, Ma J, et al. The laboratory study of the nucleation in homogeneous and heterogeneous slip fault. Science in China (in Chinese) , 2003 ,33(S1) :45-52
[9] 茂水清夫.日本的地震预报.庄灿涛等译.北京:地震出版社,1986 Mogi K. Earthquake Prediction in Japan (in Chinese). Trans, by Zhuang C T, et al. Beijing: Seismological Press. 1986
[10] King G C P. Speculations on the geometry of the initiation and termination process of earthquake rupture and its relation to morphology and geological structure. Pure and Applie Geophysics, 1986 ,124:567-585
[11] Scholz C H. The Mechanics of Earthquakes and Faulting. Cambridge; Cambridge University Press,1990
[12] Sibson R H. Rupture interaction with fault jogs. In; Das S, Boatright J, Scholz eds. Earthquake Source Mechanics. AGU Geophys. Mono. ,1986,37:157-168
[13] 马瑾.构造物理学概论.北京:地震出版社,1987 Ma J. Conspectus of Tectonic Physics (in Chinese). Beijing: Seismological Press, 1987
[14] 马瑾,马胜利,刘力强.断层几何结构与物理场的演化及失稳特征.地震学报,1996,18:200-207 Ma J, Ma S L, Liu L Q. Geometry structure of fault and evolution of physical field and destabilization characteristics. Acta Seismologica Sinica (in Chinese) ,1996,18:200-207
[15] Lei X L, Kusunose K, Satho T, et al. The hierarchical rupture process of a fault: an experimental study. Phys. Earth Planet Inter. ,2003,137:213-228
[16] 马胜利,刘力强,马瑾等.基于实验结果讨论断层破裂与强震物理过程的若干问题.地学前缘,2003,10:225-232 Ma S L, Liu L Q, Ma J, et al. A discussion on related issues of physical process of faulting and strong earthquake based on experimental results. Earth Science Frontiers (in Chinese), 2003,10:225-232
[17] Haskell N A. Total energy and energy spectral density of elastic wave radiation from propagating faults. Bull. Seism. Soc,Am. ,1964,54:1811-1841
[18] Haskell N A. Elastic displacements in the near-field of a propagating fault. Bull. Seism. Soc. Am., 1969,59:865-908
[19] Archuleta R J. A faulting model for the 1979 Imperial Valley earthquake. J. Geophys. Res. ,1984,89:4559-4585
[20] Hartzell S H, Heaton T H. Rupture history of the 1984 Morgan Hill, California, earthquake from the inversion of strong motion records. Bull. Seism. Soc. Am. ,1986,76:649-674
[21] Burridge R. Admissible speeds for plane-strain self-similar shear cracks with friction but lacking cohesion. Geophys. J. R. Astr. Soc. ,1973,35:439-455
[22] Andrews D J. Rupture velocity of plane strain shear cracks. J. Geophys. Res. ,1976,81(32) :5679-5687
[23] Madariaga R. Dynamics of an expanding circular fault. Bull. Seism. Soc. Am. ,1976,66:639-666
[24] Archuleta R J. Experimental and numerical three-dimensional simulations of strike-slip earthquakes [Ph. D. thesis]. San Diego: University of California, 1984
[25] Day S M. Three-dimensional simulation of spontaneous rupture: the effect of nonuniform prestress. Bull. Seism. Soc. Am. , 1982,72:1881-1902
[26] Hill D P, Reasenberg P A, Michael A, et al. Seismicity remotely triggered by the magnitude 7． 3 Landers, California, earthquake. Science, 1993 ,260:1617-1623
[27] Anderson J G, Brune J N, Louie J N,et al. Seismicity in the western Great Basin apparently triggered by the Landers, California, earthquake, 28 June 1992． Bull. Seism. Soc. Am. ,1994,84:863-891
[28] Bodin P, Gomberg J. Triggered seismicity and deformation between the Landers, California, and Little Skull mountain, Nevada earthquakes. Bull. Seism. Soc. Am. , 1994,84:855-843
[29] Beeler N M, Tullis T E. Self-healing slip pulses in dynamic rupture models due to velocity-dependent strength. Bull. Seism. Soc. Am. ,1996,86:1130-1148
[30] Ruina A . Slip instability and state variable friction laws. J. Geophys. Res. ,1983,88:10359-10370
[31] Oglesby D D, Day S M. Fault geometry and the dynamics of the 1999 Chi Chi (Taiwan) Earthquake. Bull. Seism. Soc. Am. ,2001,91:1099-1111
[32] Harris R A. Numerical simulations of large earthquakes:dynamic rupture propagation on heterogeneous faults. Pure and Applied Geophysics , 2004,161:2171-2181
[33] Harsha S B, Marion O, Renata D, et al. Role of fault branches in earthquake rupture dynamics. J. Geophys. Res. ,2007,112:B11309
[34] Sonia F, Harsha S B, Renata D, et al. Fault branching and rupture directivity. J. Geophys. Res. ,2005,110:B06312
[35] Stefan B, Carlson J M. Influence of friction and fault geometry on earthquake rupture. J. Geophys. Res. ,2000, 105:6069-6088
[36] Shiann J L. Kuo F M, How-Wei Chen. Effects of fault geometry and slip style on near-fault static displacements caused by the 1999 Chi-Chi. Taiwan Earthquake ,2006,241:336-350
[37] Li Q, Liu M. Geometrical impact of the San Andreas Fault on stress and seismicity in California. Geophys. Res. Lett. , 2006,33:L08302
[38] Qing S L, Mian L. Initiation of the San Jacinto Fault and its interaction with the San Andreas Fault: insights from geodynamic modeling. Pure and Applied Geophysics ,2007,164:1937-1945
[39] Oglesby D D. Earthquake dynamics on dip-slip faults [Ph. D. thesis]. Santa Barbara: University of California, 1999
[40] Andrews D J. Rupture propagation with finite stress in antiplane strain. J. Geophys. Res. ,1976,81:3575-3582
[41] Matsu'ura M, Kataoka H, Shibazaki B. Slip-dependence friction law and nucleation processes in earthquake rupture. Tectonophysics, 1992,211:135-148
[42] Dieterich J H. Modeling of rock friction 1． Experiment results and constitutive equations. J. Geophys. Res. ,1979,84:2161-2168
[43] Ruina A L. Slip instability and state variable friction laws. J. Geophys. Res. ,1983,88:10359-10370
[44] Dieterich J H. Time-dependence friction as a possible mechanism for aftershocks. J. Geophys. Res. , 1972, 77:3771-3781
[45] 马宗晋,张德成.板块构造活动与地震.见:板块构造基本问题.北京:地震出版社,1986． 363-391 Ma Z J, Zhang D C. The activity of plate and earthquakes (in Chinese). In: The Principle Problems in Plate Structure. Beijing:Seismological Press,1986． 363-391
[46] King G, Nabelek J. Role of fault bends in the initiation and termination of earthquake rupture. Science, 1985,228:984-987
[47] Sibson R H. Stopping of earthquake ruptures at dilational fault jogs. Nature, 1985 ,316:248-251
[48] Wesnousky S G. Seismological and structural evolution of strike slip faults. Nature, 1988,335:340-343
[49] Sieh K. The repetition of large-earthquake ruptures. Proc.Nad. Acad. Sci. USA ,1996,93:3764-3771
[50] 陆远忠.地震预报的地震学方法.北京:地震出版社,1985 Lu Y Z. Seismological Method of Earthquake Prediction (in Chinese). Beijing: Seismological Press, 1985
[51] Schwartz D P, Coppersmith K J. Fault behavior and characteristic earthquakes:examples from the Wasatch and San Andreas Fault zones. J. Geophys. Res. ,1984,89:5981-5998
[52] Aki K. Asperities, barriers, characteristic earthquakes and strong motion prediction. J. Geophys. Res. , 1984,89:5867-5872
[53] Bak P, Tang C. Earthquakes as a self-organized critical phenomenon. J. Geophys. Res. ,1989,94:15635-15637
[54] 李全林等.地震频度-震级关系的时空扫描.北京:地震出版社,1979 Li Q L et al. Time-Space Scanning of Seismic Frequency-Magnitude Relation (in Chinese). Beijing: Seismological Press, 1979
[55] 孙文富,顾浩鼎.具有独立过程的地震序列震级-频度分布.地震学报,1992,(3) :273-280 Sun W F, Gu H D. The seismic frequency-magnitude distribution of independent process. Acta Seismologica Sinica (in Chinese), 1992, (3) :273-280
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