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1.
本文以GPS观测、大地热流测量、较高精度地形数据、全球板块相对运动的REVEL模型为基础，建立了以青藏高原现代构造活动为主要研究对象的东亚地区构造形变场有限元模型.数值模拟结果显示，青藏高原内部和周边地区走滑断裂带的活动对东亚地区地壳运动速率和方向有较大的影响，特别是对青藏高原物质向东南方向运动有显著影响；不同构造块体岩石圈强度的差异直接影响了川滇菱形地块边界断层错动性质.在考虑青藏高原地形附加重力作用和周边板块汇聚作用对现今大型断裂带运动特征控制作用的同时，岩石圈之下的橄榄岩软流圈至转换带物质对流对岩石圈的拖曳力也是必须考虑的底部边界条件. 相似文献
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本文建立了大尺度断层（100～1000 km）的二维模型，利用ANSYS有限元软件平台，采用接触模式，模拟了百年时间尺度走滑断层的位错运动.结果表明，不同的断层力学参数，特别在断层强度非均匀分布的状态下，断层位错运动存在明显的非均匀时、空分布的特征.然而，不同模型的断层位错运动还显示出一些共同的特征，即断层位错运动表现为闭锁期、准静态预滑期和瞬间滑动，以及与之相应的应力（应变）的积累、调整和释放等等.这些结果也与实验室内小尺度的岩石物理实验相类似.与此同时，模拟结果与实际地震活动表现出的重复性和准周期特征较为相似.模拟发现，对于参数分布较为复杂的断层模型，其数值模拟提示的地震过程相对复杂得多.对于一个近尺度近1000 km，在接触面上设置了两个剪切强度相对较大区域的断层模型而言，模拟对应地震活动显示，其模拟地震断层位错分段发生，其高强度的区域基本控制了断层的地震位错运动.整个断层的模拟地震位错呈现出了地震触发、震中迁移、大震重复等与实际地震活动性相似的特征. 相似文献
3.
采用有限元方法模拟了近20万年来青藏高原岩石圈形变演化过程，探讨了印度-欧亚大陆的碰撞对中国大陆岩石层形变和应力场的影响以及它们与强地震活动性的关系.结合现代GPS、地震和地质学观测的结果，对比分析了中国大陆在百万年、十万年和十年尺度上的形变和构造应力场的基本格局.研究表明：（1）印度-欧亚大陆的碰撞以及印度大陆的持续向北推进、挤压所产生的应力环境，一直主导了以青藏高原为核心的我国西部地域岩石圈构造、运动和演化，但其影响随着远离青藏高原地区而逐渐变小.（2）断层滑移和重力势作用对于青藏高原东西部以及塔里木盆地的影响相当大，它们导致青藏高原岩石层东西向形变速率增大，对青藏高原的中南部地区产生拉张效应，同时导致塔里木盆地出现整体的右旋趋势.（3）青藏高原区域水平方向形变速率和GPS观测结果吻合较好.但在垂直方向上，一些地区计算结果与观测数据相差较大，这说明单纯的挤压作用不是现代青藏高原隆升的惟一机制.现代青藏高原的隆升可能与其他驱动机制，如地幔对流、重力均衡以及剥蚀作用等有关.（4）印度板块的挤压作用基本上决定了中国大陆西部的主压应力场分布.（5）印度板块的碰撞对中国大陆的强地震活动性有重要影响，但华北地区是个例外，该地区的地震活动性很强而印度板块的挤压在该区域产生的影响却很小，说明其他的驱动力在一定程度上活化了华北地块. 相似文献
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青藏高原东缘中南部主要活动断裂滑动速率及其地震矩亏损 总被引：9，自引：4，他引：5
作为青藏高原南东向“挤出逃逸”的重要通道，青藏高原东缘中南部具有大型走滑断裂广泛发育和地震活动强烈而频繁的特征.本文使用线性球面块体模型理论，在前人活动地块研究的基础上吸收新近研究成果，建立研究区三维块体几何模型，使用1999—2007年的GPS数据反演得到青藏高原东缘中南部主要活动断裂滑动速率.使用反演得到的滑动速率和最优断层闭锁深度估算了川滇菱形块体主要边界和其内部断裂的地震矩积累，并利用历史强震目录估算了地震矩释放，在比较两者差异的基础上得到了研究区地震矩亏损（未释放的地震矩）较大的断层和断层段，该结果可以作为研究区强震中长期危险性研究的参考. 相似文献
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作为控制断层两盘相对运动的重要因素，断裂带介质力学性能与断层面上的滑动速率及应力状态、区域地壳运动速度场等密切相关.受印度板块北东向推挤以及阿拉善地块和鄂尔多斯地块的阻挡作用，青藏高原东北缘构造变形复杂.本文在综合区域动力学环境、活动断裂空间展布以及下地壳黏滞性结构的基础上构建了青藏高原东北缘三维有限元动力学模型；以GPS速度场为约束模拟研究了断层剪切力学性能对区域地壳运动速度场图像的控制作用，进而在最优模型基础上分析了当前青藏高原东北缘不同断裂的应力状态.结果显示：阿尔金断裂东段和广义海原断裂对区域地壳运动速度场控制作用强烈，但二者剪切力学性能相反，阿尔金断裂东段断层剪切模量与周边地壳介质相当，而广义海原断裂断层剪切模量可低至周边地壳介质剪切模量的1/10000；六盘山断裂和西秦岭北缘断裂对区域地壳运动速度场的控制作用较弱，模拟结果显示二者均具有较强的剪切力学性能.基于最佳模型的应力状态分析指出：阿尔金断裂东段，广义海原断裂西段的木里—江仓断裂、中段的金强河—毛毛山—老虎山断裂、东段的六盘山断裂，以及西秦岭北缘断裂中西段当前应力率水平较高，且与前人给出的青藏高原东北缘高闭锁区域吻合.动力学上的高应力率与运动学上的强闭锁良好吻合，预示着这些断裂是地震危险分析值得关注的区域. 相似文献
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提出一种二维地震断层破裂模式，这是在一维弹簧-滑块模式的基础上建立的．利用这种断层的二维向量模型，研究了地震断层的动力学平面-应变的破裂问题．形象、直观地模拟了具有均匀或不均匀破裂强度分布的二维地震断层的破裂成核、扩展、传播直至停止的动力学全过程．阐明了在均匀预应力条件下，断层将获得足够的动量以克服破裂传播路径上的高强度障碍体．破裂锋面亦可绕过孤立的障碍体继续向前传播．整个模拟过程表明:断层破裂过程的停止条件对模拟地震破裂的全过程起着重要作用；我们还研究了断层面上破裂强度分布不均匀条件下断层的动态破裂过程，模拟了具有分形结构强度分布的二维地震断层产生的地震序列．它具有类似自然界地震现象的某些特征．这些特征主要取决于断层面上破裂强度的分布及初始应力降的大小．建立在实验和观测基础上的断层破裂过程模拟研究，为解释地震活动性统计规律的某些特征提供了物理基础. 相似文献
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本文用三维非连续变形与有限元相结合（DDA+FEM）的方法，在青藏川滇地区三维构造块体相互制约的大背景中，通过用GPS资料做位移速率边界约束和震源机制约束，计算得到研究区的初始位移场和应力场与该地区GPS测量结果和震源机制分布结果基本一致.在此基础上进一步数值模拟1997年玛尼7.9级大震的发生过程，研究大震引起研究区各块体边界断层应力状态变化的特征.（1）发震断层两侧发生左旋走滑错动，最大水平位错大约7 m；（2）深部位错面上位错分布与用地震波资料震源反演的结果类似；（3）最大差应力变化等值线图与由星载D\|INSAR技术获取的地表形变场图像相似；（4）地表垂直位移表明地震断层面略向北逆冲.计算模拟得到了玛尼地震发生引起青藏川滇地区构造块体系统各边界断层上库仑破裂应力变化的分布，表明玛尼大震的发生除了使其发震断层的两端库仑破裂应力增大，应力进一步集中外，位于上地壳层上东昆仑断裂中段的2001年昆仑山8.1大震（H=11 km）发震断层段的库仑破裂应力增加约2 MPa，位于中地壳层上喀拉昆仑断裂带中的2008年改则6.9级地震（H=30 km）发震断层段的库仑破裂应力也增加约0.7 MPa，可见这两个已接近破裂强度地段的失稳对发生大震起了一定促进作用.研究结果也表明：作者发展的三维DDA+FEM方法能有效地用于大震活动与各构造块体相互作用关系的研究. 相似文献
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根据活动断裂分布和区域流变结构建立川滇地区三维有限元模型， 采用上地壳为弹性介质，下地壳和上地幔为Maxwell体的粘弹性模型，模拟川滇地区地壳现今运动和应力分布，探讨川滇地区地壳运动变形的动力学机制. 通过4种不同边界条件和深度分层结构有限元模型的计算结果的对比，认为川滇地区绕喜玛拉雅东构造结顺时针旋转的地壳运动模式主要受川滇地区特殊的边界动力作用控制，川滇菱形块体下地壳流动对上地壳的拖曳作用亦不容忽视. 同时，川滇地区各块体的现今地壳运动场和应力场还受到区域主要活动断裂带的影响， 呈现分块特征. 相似文献
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青藏高原的隆升过程与地球动力学模型研究进展 总被引：8，自引：2，他引：8
综合对比、分析了现有青藏高原隆升过程和地球动力学模型相关成果，认为：（1）高原岩石圈以多圈层为特征，其内部层圈相互作用复杂，从而导致隆升过程和机制的复杂性以及构造演化的阶段性，高原的隆升是多种机制联合作用的产物，具有多阶段、非均一、不等速的特征；（2）现有地球动力学模式多力求用一种动力学体制对高原整体构造格架和成因演化进行解释，然而，高原的隆升过程、状态和动力学机制具有非线性、非周期性和无序性等特征，其隆升作用存在非线性效应；（3）以数值模拟为手段，开展物理与数学的定量模拟研究，建立组合动力学模型，是青藏高原隆升过程和地球动力学研究中有待深化的重要课题。 相似文献
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2008年5月12日四川汶川地区发生MW7.9地震，震中位置103.4°E，31.06°N.这次地震造成了以汶川、映秀为中心及其周边地域建筑物的严重破坏和人员的重大伤亡，且因为高山等地形复杂区域抢险救灾的艰巨性，为及时救援造成很大干扰.为更好理解地形因素对于强地面数值模拟结果的影响，建立了包含地形起伏影响及去除地形影响的两类模型.同时，依据震源破裂过程运动学反演结果，建立了包含障碍体破裂过程的震源滑动模型，实现断层分段、空间倾角以及滑移角的动态设定.基于动力学的地震动模拟方法，通过对地震波传播过程的数值计算和后处理分析，模拟由地震激发的区域强地面运动过程.结果显示：（1）强震动台站的断层距对地形效应具有放大或抑制作用，距离断层破裂带越近，地形效应越明显，反之，距离越远，则地形效应越微弱；（2）因为地形高差与障碍体的影响，地震造成的峰值可能出现在震中区域之外；（3）考虑地形影响模型的地表峰值速度（PGV）区域位于汶川与北川附近；而未考虑地形影响模型的PGV区域位于灌县—江油断层的后半段，处清平、安县附近；对汶川地震近实时强地面运动波场的模拟、峰值图谱的圈定及未来大地震强地面运动特征的预测都有重要指示意义. 相似文献
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以青藏高原北缘及东北缘的柴达木-祁连山地块内的活动断裂、由断裂所围限的微小块体为研究对象,系统收集整理区内活动断裂定量参数和GPS速度场等资料,使用球面应变率计算方法分析研究区内GPS 速度场得到现今构造应变率场,讨论区内最大剪应变率、面膨胀率与旋转率等参数与区域构造变形之间的关系;同时,依据区内详实的活动断裂资料建立精细的微小活动块体模型,利用Backslip模型反演断裂所围限的各个块体边界断裂的滑动速率、块体内部统一应变率及块体欧拉运动学参数等,并与活动构造方法获得的滑动速率做对比;最后,讨论研究区内由GPS速度场所揭示的地壳运动变形模式.结果表明:(1)柴达木-祁连山地区地壳运动,在沿着山脉走向上具有带状区域分块运动特征,大范围内具有弥散变形特征;(2)青藏高原北部变形场应是通过不同断裂差异性相对运动、区域内部逆冲挤压和块体旋转共同作用的结果.从鄂拉山到古浪民勤一带具有强烈的逆冲活动,其两侧地壳块体分别具有逆向旋转的运动性质;(3)在研究区东部GPS速度场所呈现顺时针旋转的形态,应是处于不同地块边界处的中下地壳与地幔介质差异驱动机制对上地壳块体所产生的作用,并以近地表断层应变率积累形式表现的结果,是祁连山地块、阿拉善块体、鄂尔多斯地块等大型块体推挤旋转影响下的复杂运动学形态. 相似文献
12.
Yong Zheng Xiong Xiong Yong Chen Bin Shan Key Laboratory of Dynamic Geodesy 《地震学报(英文版)》2011,(2):185-197
We compare the factors which affect the movement of Tibetan Plateau by building three types of finite element models: an elastic materials (M-EC), a continuous model composed by non-linear materials (M-PC), and an elastic model with discontinuous fault movements (M-ET). Both in M-ET and M-EC, the materials in Qiangtang and Lhasa block are elastic, and in M-ET, discontinuous movement of faults is considered for evaluating the effects of strike-slip faults. In model M-PC Druker-Prager plastic materials are us... 相似文献
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ESTIMATING THE LOWER CRUSTAL VISCOSITY OF THE WESTERN QINLING-SONGPAN TECTONIC NODE AND ITS ADJACENT AREAS BY USING LANDFORM MORPHOLOGY 
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下载免费PDF全文 The western Qinling-Songpan tectonic node is located at the intersection of three major tectonic units of Tibetan plateau, the South China Block and the Ordos Block, and is at the forefront of the northeastern margin of Tibetan plateau. It has unique geological and dynamic characteristics from the surface to the deep underground. Based on the model for ductile flow in the lower crust, the geomorphological form is used to estimate the viscosity of the lower crust, and how the rheological process of the deep lithosphere acts on the upper crust deformation and structural geomorphology. And combined with GPS velocity field data, the current crustal deformation is analyzed to further study the regional dispersive deformation process. The results show that the viscosity of the north and northeast of the Zoige-Hongyuan Basin is smaller than that of the east and southeast. Therefore, the lower crust flow has a tendency of flowing to the northeastern low viscosity zone. We believe that when the lower crust flows from the central plain of the Qinghai-Tibet Plateau to the rigid Sichuan Basin with a higher viscosity of the lower crust, it cannot flow into the basin, and part of the lower crust flow accumulate here, causing the upper crust to rise, and the uplifting led to the formation of the Longmen Mountains and a series of NNE-striking faults as well. When the lower crust flows to the northeast direction with a low viscosity, the brittle upper crust is driven together. Because of the remote effects from the Ordos Basin and the Longxi Basin, the mountains in this region are built slowly and the stepped arc-shaped topography of the current 3 000-meter contour line and the 2 000-meter contour line are developed. At the same time, a series of NWW-trending left-lateral strike-slip faults are developed. This explains the seismogenic tectonic model of the western Qinling-Songpan tectonic node as from NWW-trending left-lateral strike-slip faulting to the NNE-trending right-lateral strike-slip faulting and both having a thrust component. The current crustal movement direction revealed by the GPS velocity field is consistent with the direction of historical crust evolution of the lower crust revealed by the viscosity, implying that there is a good coupling relationship between the lower crust and upper crust. The results provide a basis for studying the development of fault systems with different strikes and properties, the formation of orogenic belts, the macroscopic geomorphological evolution characteristics, and the rheological and uplift dynamics of the lithosphere in the northeastern margin of the Tibetan plateau.
In addition, our research differs from the previous studies in the spatial and temporal scale. Previous studies included either the entire Qinghai-Tibet Plateau or only the eastern margin of the Qinghai-Tibet Plateau. However, our analysis on the contours and topographical differences in the topography of the western Qinling-Songpan tectonic knot reveals that the study area is controlled by the lower crust flow. Our results are confirmed by various observations such as seismology, magnetotellurics and geophysical exploration. Moreover, the previous studies did not point out enough that the elevation contours are elliptical, and the elliptical geomorphology further illustrates that the formation and evolution of the Qinghai-Tibet Plateau has rheological characteristics and also conforms to the continuous deformation mode. Meanwhile, in terms of time scale, the evolution time of the study area is divided into three types of simulation time according to geochronology. And the GPS velocity field is introduced to observe the present-day crustal deformation. 相似文献
14.
探讨地壳运动速度场模型的构建方法,提出结合欧拉矢量的维多样性动态权重粒子群算法构建地壳运动速度场模型。通过模拟算例验证该算法的稳定性和有效性,建立的速度场模型与线性权重粒子群算法和非线性权重粒子群算法的计算结果相比具有较高的精度,且收敛速度较快。利用青藏高原东北缘1999—2013年中国地壳运动观测网络观测到的GPS水平速率结果,在块体划分和模型辨识的基础上,建立青藏高原东北缘地壳运动速度场模型,并将其与最小二乘配置法的计算结果进行比较,结果表明改进的粒子群算法建立的地壳运动速度场模型具有较高的精度。 相似文献
15.
Present-day horizontal deformation status of continental China and its driving mechanism 总被引：2，自引：0，他引：2
CHEN XiaoBin Institute of Geology China Earthquake Administration Beijing China 《中国科学D辑(英文版)》2007,50(11):1663-1673
Based on velocity data of 933 GPS sites and using the methods of Ordinary Kriging interpolation and shape function derivation, this study has obtained the strain rate field of continental China in the spherical coordinates. In comparison with previous research results, it is found that such a strain rate field can be described by both the continuous deformation and block motions in the continent. The Tibetan Plateau and Tianshan region are characterized by continuous deformation which is distributed across the whole area. Within the blocks of South China, Tarim, Ordos, and Northeast China, little crustal deformation and deformation occurs primarily on the faults along their boundaries, which can be explained by the model of block motion. In other regions, such as the Yinshan-Yanshan block, North China block, and East Shandong-Yellow Sea, deformation patterns can be explained by both models. Besides, from southwest to northeast of continental China, there are three remarkable extensional zones of NW trending. These results imply that the NNE directed push of the India plate is the primary driving force accounting for the internal deformation of continental China. It produces the uplift, hori-zontal shortening and vertical thickening of the Tibetan Plateau as well as radiation-like material extru-sion. Of these extruded materials, one part accommodates the eastward "escape" of other blocks, generating convergence and compression of western China and widespread extension and local com-plicated deformation in eastern China under the joint action of the surrounding settings. The other part opens a corridor between the South China block and Tibetan Plateau, flowing toward southeast to the Myanmar range arc and filling the gap there which is produced by back-arc extension due to plate subduction. 相似文献
16.
本文采用欧拉反褶积、场源参数成像(SPI)、场源边界提取(SED)、莫霍面反演、地壳三维可视化等多源方法,对青藏高原东北缘地区的布格重力场进行反演与分析,深入研究该地区的深部结构与变形特征,探讨区域深部孕震环境及动力学机制.研究表明,青藏高原东北缘的布格重力场整体呈负异常值,具有明显的分区性,表现出鄂尔多斯盆地异常值相对偏高、阿拉善块体次之、青藏高原块体极低的特点,其中海源断裂系形成了一条宽缓的弧形重力梯度条带,梯度值达1.2 mGal·km^-1.欧拉结果显示,鄂尔多斯盆地相比于青藏高原块体而言,场源点具有较强的均一性,场源强度值高(密度值高)且深度稳定在25~32 km范围内,而高原块体的中下地壳尺度广泛分布着低密度异常体.SPI图可知,海源弧形断裂系位于“浅源异常”弧形区,反映其地壳较为活跃,易发生中强地震.SED图揭示青藏高原地壳向东北扩展,经过几大断裂系的调节后运动矢量向东或东南转化,SED与GPS、SKS运动特征大致相同,说明地表-地壳-地幔的运动特征有着较强的一致性.青藏高原东北缘地区壳幔变形是连贯的,加之莫霍面由北向南、由东向西是逐渐加深的,因此属于垂向连贯变形机制,不符合下地壳管道流动力学模式.区域形成了似三联点构造格局,其中海源弧形断裂系的深部地壳结构复杂,高低密度异常体复杂交汇,是青藏高原、阿拉善、鄂尔多斯三大块体相互作用的重要枢纽,其运动学特征总体为中段走滑尾端逆冲,而断裂系正处于大型的弧形莫霍面斜坡带之上,具备强震的深部孕震环境,因此大尺度的运动调节与深部孕震条件共同促使了该地区中强震的多发. 相似文献
17.
Min Wang Zhengkang Shen Zhijun Niu Zusheng Zhang Hanrong Sun Weijun Gan Qi Wang Qun Ren 《中国科学D辑(英文版)》2003,46(2):25-40
We obtain the preliminary result of crustal deformation velocity field for the Chinese continent by analyzing GPS data from the Crustal Motion Observation Network of China (CMONOC), particularly the data from the regional networks of CMONOC observed in 1999 and 2001. We delineate 9 technically active blocks and 2 broadly distributed deformation zones out of a dense GPS velocity field, and derive block motion Euler poles for the blocks and their relative motion rates. Our result reveals that there are 3 categories of deformation patterns in the Chinese continent. The first category, associated with the interior of the Tibetan Plateau and the Tianshan orogenic belt, shows broadly distributed deformation within the regions. The third category, associated with the Tarim Basin and the region east of the north-south seismic belt of China, shows block-like motion, with deformation accommodated along the block boundaries only. The second category, mainly associated with the borderland of the Tibetan Plateau, such as the Qaidam, Qilian, Xining (in eastern Qinghai), and the Diamond-shaped (in western Sichuan and Yunnan) blocks, has the deformation pattern between the first and the third, i.e. these regions appear to deform block-like, but with smaller sizes and less strength for the blocks. Based on the analysis of the lithospheric structures and the deformation patterns of the regions above, we come to the inference that the deformation modes of the Chinese continental crust are mainly controlled by the crustal structure. The crust of the eastern China and the Tarim Basin is mechanically strong, and its deformation takes the form of relative motion between rigid blocks. On the other hand, the northward indentation of the Indian plate into the Asia continent has created the uplift of the Tibetan Plateau and the Tianshan Mountains, thickened their crust, and raised the temperature in the crust. The lower crust thus has become ductile, evidenced in low seismic velocity and high electric conductivity observed. The brittle part of the crust, driven by the visco-plastic flow of the lower crust, deforms extensively at all scales. The regions of the second category located at the borderland of the Tibetan Plateau are at the transition zone between the regions of the first and the third categories in terms of the crustal structure. Driven by the lateral boundary forces, their deformation style is also between the two, in the form of block motion and deformation with smaller blocks and less internal strength. 相似文献