龙门山断层地震周期及其动力学过程模拟研究

doi:10.6038/cjg2018M0226

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摘要在断层面上引入速率-状态相依摩擦本构关系、考虑铲形逆冲断层几何结构特征、断层下盘和上盘中下地壳及上地幔为黏弹性介质、上盘上地壳为弹塑性介质，本文用二维有限元动力学模型模拟了龙门山断层上大震准周期复发行为、分析了断层上地震孕育位置、地震周期不同阶段的应力/应变场演化特征.不同于近垂直走滑断层上的地震周期行为，大陆铲形逆冲断层上的构造应力的积累和释放过程更复杂、有其独特性.我们得到如下认识：（1）铲形逆冲断层上的地震复发是准周期行为.（2）龙门山断层最大库仑应力位于断层17~20 km深处，应力长期积累和同震释放都在此深度最大，说明地震会在此处孕育、发动.（3）在断层破裂的深部和浅部，同震滑动大小和构造应力释放大小并非同步，而是差异悬殊.（4）地震仅部分释放区域积累的应变能，断层上盘上地壳顶部和底部的褶皱、破裂等永久变形形式也是释放应变能的重要形式.（5）应变能密度增量的演化图像分为：震间、同震、震后期，清晰反应了龙门山断层附近的地震动力学过程.（6）地震发生除释放能量外，同时也对近断层的中地壳和断层底部有很大的应变能加载；这些加载，在震后期可能通过震后滑移、余震或中下地壳乃至上地幔的驰豫形变用几十年时间释放.以上对大陆内铲形逆冲断层上变形特征的了解，有助于我们在其地震周期行为中评估地震危险性.

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关键词 ：铲形逆冲断层, 龙门山断层, 地震周期行为, 速率-状态相依摩擦本构关系, 动力学模型

Abstract：We simulate the earthquake dynamic process of Longmen Shan fault over earthquake cycles using a 2-D finite element model, taking into account of the fault geometry, media mechanical property, and rate-state friction law on fault. The system is driven laterally by constant tectonic loading and gravity. The tectonic stress accumulation and release on a continental listric fault system have some unique features comparing with those of a vertical strike-slip fault system. Based on numerical simulation of stress/strain evolution over earthquake cycles, we find that: (1) Quasi periodicity of earthquake cycles emerged in the simulation. (2) The maximum Coulomb stress and Mises stress accumulating and releasing are located in the depth of 17~20 km, where probably is the seismogenetic region on the fault. (3) The coseismic slip and Coulomb stress release show a disparity between the upper and lower part of the fault rupture, with larger slip and lower stress release near surface and smaller slip and greater stress release at down dip of the fault rupture consistent with seismic and geodetic coseismic study results. (4) Tectonic stress and strains are accumulated interseismically, and released partially by periodical and partially by the permanent deformation and folding in upper crust. (5) The dynamic process of earthquake cycle is demonstrated clearly by the strain energy density increment patterns during the interseismic, coseismic and poseismic periods. (6) Strain energy also accumulated within the lower part of the seismogenic layer during the coseismic time period, and can be released post-seismically through aftershock and viscous deformation close to fault around the downdip end of the fault rupture. The result will enhance our knowledge on fault zone physical process deformation mechanisms. Characterization of these deformation features helps assess seismic potentials over an earthquake cycle.

Key words： Listric thrust fault Longmen Shan fault Earthquake cycle Rate-state friction law Dynamic modeling

收稿日期: 2018-03-06

PACS:

P313

基金资助:国家自然科学基金项目（41374103）资助.

通讯作者: 陶玮,女,1971年生,博士,副研究员,主要从事地震动力学模拟研究.E-mail:664159723@qq.com E-mail: 664159723@qq.com

作者简介: 马林飞,男,1990年生,硕士生,主要从事地震动力学模拟研究.

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http://manu39.magtech.com.cn/Geophy/CN/10.6038/cjg2018M0226 或 http://manu39.magtech.com.cn/Geophy/CN/Y2018/V61/I5/1824

Abaqus. 2011. Version 6. 11-EF, Dassault Systèmes Simulia Corp., Providence, RI, www.simulia.com.
Bürgmann R, Dresen G. 2008. Rheology of the lower crust and upper mantle: Evidence from rock mechanics, geodesy, and field observations. Annual Review of Earth and Planetary Sciences, 36(1): 531-567.
Bai D H, Unsworth M J, Meju M A, et al. 2010. Crustal deformation of the eastern Tibetan plateau revealed by magnetotelluric imaging. Nature Geoscience, 3(5): 358-362.
Beeler N M, Tullis T E, Weeks J D. 1994. The roles of time and displacement in the evolution effect in rock friction. Geophysical Research Letters, 21(18): 1987-1990.
Burchfiel B C, Chen Z L, Liu Y P, et al. 1995. Tectonics of the Longmen Shan and adjacent regions, central China. International Geology Review, 37(8): 661-735.
Chen G H, Xu X W, Yu G H, et al. 2009. Co-seismic slip and slip partitioning of multi-faults during the M_S8.0 2008 Wenchuan earthquake. Chinese Journal of Geophysics (in Chinese), 52(5): 1384-1394.
Clark M K, Royden L H. 2000. Topographic ooze: Building the eastern margin of Tibet by lower crustal flow. Geology, 28(8): 703-724.
Clark M K, Bush J W M, Royden L H. 2005. Dynamic topography produced by lower crustal flow against rheological strength heterogeneities bordering the Tibetan Plateau. Geophysical Journal International, 162(2): 575-590.
HuangJ L, Zhao D P, Zheng S H. 2007. Lithospheric structure and its relationship to seismic and volcanic activity in southwest China. Journal of Geophysical Research: Solid Earth, 107(B10): 2255, doi: 10.1029/2000JB000137.
Hubbard J, Shaw J H. 2009. Uplift of the Longmen Shan and Tibetan plateau, and the 2008 Wenchuan (M=7.9) earthquake. Nature, 458(7235): 194-197.
Hubbard J, Shaw J H, Klinger Y. 2010. Structural setting of the 2008 M_W7.9 Wenchuan, China, earthquake. Bulletin of the Seismological Society of America, 100(5B): 2713-2735.
JiaD, Li Y Q, Lin A M. 2010. Structural model of 2008 M_W7.9 Wenchuan earthquake in the rejuvenated Longmen Shan thrust belt, China. Tectonophysics, 491(1-4): 174-184.
Li H B, Wang H, Xu Z Q, et al. 2013. Characteristics of the fault-related rocks, fault zones and the principal slip zone in the wenchuan Earthquake Fault Scientific Drilling Project Hole-1 (WFSD-1). Tectonophysics, 584: 23-42.
Li Y X, Zhang J H, Zhou W, et al. 2009. The mechanism and dynamics of the generation and occurrence for Wenchuan M_S8.0 earthquake. Chinese Journal of Geophysics (in Chinese), 52(2): 519-530.
Liu Q Y, Van Der Hilst R D, Li Y, et al. 2014. Eastward expansion of the Tibetan Plateau by crustal flow and strain partitioning across faults. Nature Geoscience, 7(5): 361-365.
Liu Q Y, LI Y, Chen J H, et al. 2009. Wenchuan M_S8.0 earthquake: Preliminary study of the S-wave velocity structure of the crust and upper mantle. Chinese Journal of Geophysics (in Chinese), 52(2): 309-319.
Ran Y K, Chen L C, Chen G H, et al. 2008. Primary analyses of In-situ recurrence of large earthquake along seismogenic fault of the M_S8.0 Wenchuan earthquake. Seismology and Geology (in Chinese), 30(3): 630-643.
Ran Y K, Chen L C, Chen J, et al. 2010. Paleoseismic evidence and repeat time of large earthquakes at three sites along the Longmenshan fault zone. Tectonophysics, 491(1-4): 141-153.
Robert A, Zhu J S, Vergne J, et al. 2010. Crustal structures in the area of the 2008 Sichuan earthquake from seismologic and gravimetric data. Tectonophysics, 491(1-4): 205-210.
Royden L H, Burchfiel B C, King R W, et al. 1997. Surface deformation and lower crustal flow in eastern Tibet. Science, 276(5313): 788-790.
Royden L H, Burchfiel B C, Van Der Hilst R D. 2008. The geological evolution of the Tibet Plateau. Science, 321. 1054_1058. doi:10.1126/science.1155371.
Ryder I, Bürgmann R, Pollitz F. 2011. Lower crustal relaxation beneath the Tibetan Plateau and Qaidam Basin following the 2001 kokoxili earthquake. Geophysical Journal International, 187(2): 613-630.
Scholz C H. 1988. Earthquakes and friction laws. Nature, 391(6662): 37-42.
Scholz C H. 1990. The Mechanics of Earthquakes and Faulting. Cambridge: Cambridge University Press.
Shen F. Royden L H, Burchfiel B C. 2001. Large-scale crustal deformation of the Tibetan Plateau. Journal of Geophysical Research: Solid Earth, 106(B4): 4793-6816.
Shen Z K, Sun J B, Zhang P Z, et al. 2009. Slip maxima at fault junctions and rupturing of barriers during the 2008 Wenchuan earthquake. Nature Geoscience, 2(10): 718-724.
Shi Y L, Cao J L. 2008. Effective viscosity of China continental lithosphere. Earth Science Frontiers (in Chinese), 15(3): 82-95.
Tao W, Hu C B, Wan Y G, et al. 2011. Dynamic modeling of thrust earthquake on listric fault and its inference to study of Wenchuan earthquake. Chinese Journal of Geophysics (in Chinese), 54(5): 1260-1269, doi: 10.3969/j.issn.0001-5733.2011.05.015.
TaoW, Masterlark T, Shen Z K, et al. 2015. Impoundment of the Zipingpu reservoir and triggering of the 2008 M_W7.9 Wenchuan earthquake, China. Journal of Geophysical Research: Solid Earth, 120(10): 7033-7047, doi: 10.1002/2014JB011766.
Tapponnier P, Xu Z Q, Roger F, et al. 2001. Oblique stepwise rise and growth of the Tibet plateau. Science, 294(5547): 1671-1677.
Wang C Y, Han W B, Wu J Q, et al. 2007. Crustal structure beneath the eastern margin of the Tibetan Plateau and its tectonic implications. Journal of Geophysical Research: Solid Earth, 112(B7): B07307, doi: 10.1029/2005JB003873.
Wang F. 2012. Strong earthquake effect, postseismic deformation and its mechanism (in Chinese). Beijing: Institute of Geology, CEA, 1-107.
Wang Q, Qiao X J, Lan Q G, et al. 2011. Rupture of deep faults in the 2008 Wenchuan earthquake and uplift of the Longmen Shan. Nature Geoscience, 4(9): 634-640, doi: 10.1038/NGEO1210.
Wang Y X, Mooney W D, Han G H, et al. 2005. The crustal P-wave velocity structure from Altyn Tagh to Longmen mountains along the Taiwan-Altay geoscience transect. Chinese Journal of Geophysics (in Chinese), 48(1): 98-106.
Wang Y Z, Wang M, Shen Z K, et al. 2011. Inter-seismic deformation field of the Ganzi-Yushu fault before the 2010 Yushu earthquake. Seismology and Geology (in Chinese), 33(3): 525-532.
Zang S X, Wei R Q, Liu Y G. 2005. Three-dimensional rheological structure of the lithosphere in the Ordos block and its adjacent areas. Geophysical Journal International, 163(1): 339-356, doi: 10.1111/j.1365-246X.2005.02745.x.
Zhang P Z, Xu X W, Wen X Z, et al. 2008. Slip rates and recurrence intervals of the Longmen Shan active fault zone, and tectonic implications for the mechanism of the May 12 Wenchuan earthquake, 2008, Sichuan, China. Chinese Journal of Geophysics (in Chinese), 51(4): 1066-1073.
Zhang P Z, Wen X Z, Shen Z K, et al. 2010. Oblique, high-angle, listric-reverse faulting and associated development of strain: The Wenchuan earthquake of May 12, 2008, Sichuan, China. Annual Review of Earth and Planetary Sciences, 38(1): 353-382, doi: 10.1146/annurev-earth-040809-152602.
Zhang Z J, Wang Y H, Chen Y, et al. 2009. Crustal structure across Longmenshan fault belt from passive source seismic profiling. Geophysical Research Letters, 36(17): L17310, doi: 10.1029/2009GL039580.
Zhao G Z, Unsworth M J, Zhan Y, et al. 2012. Crustal structure and rheology of the Longmenshan and Wenchuan M_W7.9 earthquake epicentral area from magnetotelluric data. Geology, 40(12): 1139-1142.
Zhou S Y. 2008. Seismicity simulation in Western Sichuan of China based on the fault interaction sand its implication on the estimation of the regional earthquake risk. Chinese Journal of Geophysics (in Chinese), 51(1): 165-174.
Zhou Y S, He C R. 2009. The rheological structures of crust and Mechanics of high-angle reverse fault slip for Wenchuan M_S8.0 earthquake. Chinese Journal of Geophysics (in Chinese), 52(2): 474-484.
Zhu A L, Xu X W, Zhou Y S, et al. 2005. Relocation of small earthquakes in western Sichuan, China and its implications for active tectonics. Chinese Journal of Geophysics (in Chinese), 48(3): 629-636.
Zhu A L, Xu X W, Diao G L, et al. 2008. Relocation of the M_S8.0 Wenchuan earthquake sequence in part: Preliminary seismotectonic analysis. Seismology and Geology (in Chinese), 30(3): 759-767.
Zhu J S. 2008. The Wenchuan earthquake occurrence background in Deep Structure and dynamics of lithosphere. Journal of Chengdu University of Technology (Science & Technology Edition) (in Chinese), 35(4): 348-356.
Zhu S B, Cai Y E, Shi Y L. 2006. The contemporary tectonic strain rate field of continental China Predicted from GPS measurements and its geodynamic implications. Pure and Applied Geophysics, 163(8): 1477-1493.
Zhu S B, Zhang P Z. 2009. A study on the dynamical mechanisms of the Wenchuan M_S8.0 earthquake, 2008. Chinese Journal of Geophysics (in Chinese), 52(2): 418-427.
Zhu S B, Zhang P Z. 2010. Numeric modeling of the strain accumulation and release of the 2008 Wenchuan, Sichuan, China. Bulletin of the Seismological Society of America, 100(5B): 2825-2839.
附中文参考文献
陈桂华, 徐锡伟, 于贵华等. 2009. 2008年汶川M_S8.0地震多断裂破裂的近地表同震滑移及滑移分解. 地球物理学报, 52(5): 1384-1394.
李延兴, 张静华, 周伟等. 2009. 汶川M_S8.0地震孕育发生的机制与动力学问题. 地球物理学报, 52(2): 519-530.
刘启元, 李昱, 陈九辉等. 2009. 汶川M_S8.0地震: 地壳上地幔S波速度结构的初步研究. 地球物理学报, 52(2): 309-319.
冉永康, 陈立春, 陈桂华等. 2008. 汶川M_S8.0地震发震断裂大地震原地重复现象初析. 地震地质, 30(3): 630-643.
石耀霖, 曹建玲. 2008. 中国大陆岩石圈等效粘滞系数的计算和讨论. 地学前缘, 15(3): 82-95.
陶玮, 胡才博, 万永革等. 2011. 铲形逆冲断层地震破裂动力学模型及其在汶川地震研究中的启示. 地球物理学报, 54(5): 1260-1269, doi: 10.3969/j.issn.0001-5733.2011.05.015.
王凡. 2012. 强震效应、震后形变及其机制. 北京: 中国地震局地质研究所, 1-107.
王有学, Mooney W D, 韩果花等. 2005. 台湾—阿尔泰地学断面阿尔金—龙门山剖面的地壳纵波速度结构. 地球物理学报, 48(1): 98-106.
王阎昭, 王敏,沈正康等. 2011. 2010年玉树地震震前甘孜—玉树断裂形变场分析. 地震地质, 33(3): 525-532.
张培震, 徐锡伟, 闻学泽等. 2008. 2008年汶川8.0级地震发震断裂的滑动速率、复发周期和构造成因. 地球物理学报, 51(4): 1066-1073.
周仕勇. 2008. 川西及邻近地区地震活动性模拟和断层间相互作用研究. 地球物理学报, 51(1): 165-174.
周永胜, 何昌荣. 2009. 汶川地震区的流变结构与发震高角度逆断层滑动的力学条件. 地球物理学报, 52(2): 474-484.
朱艾斓, 徐锡伟, 周永胜等. 2005. 川西地区小震重新定位及其活动构造意义. 地球物理学报, 48(3): 629-636.
朱艾斓, 徐锡伟, 刁桂苓等. 2008. M_S8.0地震部分余震重新定位及地震构造初步分析. 地震地质, 30(3): 759-767.
朱介寿. 2008. 汶川地震的岩石圈深部结构与动力学背景. 成都理工大学学报(自然科学版), 35(4): 348-356.
朱守彪, 张培震. 2009. 2008年汶川M_S8.0地震发生过程的动力学机制研究. 地球物理学报, 52(2): 418-427.