中国大陆现今地壳水平运动

在重新仔细处理了1994和1996年中国大陆地壳运动监测网两次GPS测量资料的基础上,采用较为完善的块体相对运动和块体内变形叠加的变形模型和相应的分析方法,研究了中国大陆现今地壳运动的运动学特征,并定量计算和比较了主要活动构造块体边界带的活动性质和强度,得到了一些新的认识．      

Numerical Simulation of Annual Change Patterns of Contemporary Tectonic Stress-Strain Field of the Chinese Mainland

INTRODUCTIONInthe late 1980’s ,aninternational cooperation project in earth sciences ,the World Stress MapProject ,wasinitiated underthe World Lithosphere Program. Measurements andresearch achievementsof the present-daytectonic stress field worldwide were analyzed and sorted out .The project achievedgood results and based on them, a world stress database was set up,the world stress map wascompiled,andthe general andregional crustal stress patterns were discussed (Zoback,et al .,1989 ;…     

中国大陆现今地应力场黏弹性球壳数值模拟综合研究

中国大陆现今实测地应力场的状态与板块构造环境、活动断裂带分布、地形地貌以及地壳结构呈现一定相关性. 在中国大陆西缘,印度洋板块与欧亚板块陆发生陆碰撞,在中国大陆东缘,菲律宾海板块、太平洋板块俯冲到欧亚板块之下. 中国大陆内部被大型活动断裂带分割为多个块体,各个块体的地壳结构和厚度呈不均匀分布,地形地貌起伏具有很大的差异. 笔者以中国大陆块体模型为基础,把板块构造作用和重力势作为主要影响地应力状态的两个主要要素,在现今活动构造、GPS和实测地应力等成果的约束下,利用线性黏弹体球壳有限元模拟分析了中国大陆现今地应力场的分布特征和控制因素. 结果表明: (1)构造应力场总体上呈现出西部挤压,东部拉张的特征,印度板块与欧亚板块的持续碰撞形成了青藏高原及其周缘的挤压性质的构造应力场,而东部菲律宾板块与太平洋板块的俯冲形成了黄海、东海和环渤海区域的拉张性质的构造应力场,中间为拉张环境和挤压环境的过渡,最大主应力的方向受到板块构造环境和活动构造分布的控制;(2)重力的影响主要体现在地形梯度大和地壳厚度结构变化大的地壳浅部区域,在藏南、滇西北局部地区的地壳浅部由于受到重力势控制,呈现为张性应力场,在塔里木地区由于重力势引起的应力场与构造应力场同为挤压性质,因此该区的挤压强度得以增加;(3)中国大陆浅部地应力场的状态主要受到区域板块构造环境、块体边界活动构造带的展布和地形的控制,总体上以南北构造带为界,西部以较强的压性构造环境为主,东部为较弱的压性构造环境,藏南和滇西北局部地区存在有张性构造环境;构造应力对地应力的贡献比重随着深度增加而增加;(4)采用黏弹性模型的构造应力场模拟结果比完全弹性模型的模拟结果能够更好地与实测地应力场相吻合,利用完全弹性模型分析由地震等诱发的地应力瞬时变化是有效的;(5)青藏高原东南缘最大主应力方向发生了较大的偏转,其主要控制因素有:印度板块持续的碰撞、中下地壳对上地壳拖曳以及印度板块通过实皆断裂对欧亚板块的剪切拉伸作用. 中国大陆现今地应力场是整个地壳岩石黏弹特性长期演化和断裂活动的结果,是地应力场动态演化过程中在现今时间点上的状态,受到板块构造环境、大陆内部活动断裂分布、地形地貌和地壳结构等因素不同程度的控制,模拟结果为中国大陆地应力场提供了一个定量的参考模型.     

中国大陆活动地块边界带与强震活动

本文在前人对中国大陆及周边活动地块研究和划分的基础上，系统研究了6个Ⅰ级活动地块区和22个Ⅱ级活动地块之间共26个活动边界带的构造变形与强震活动，包括强震分布与活动边界带的关系，边界带构造活动速率与地震活动水平及强震复发期等的关系. 给出了边界带强震活动水平与构造活动速率之间的线性关系和强震复发期长短与构造活动速率的反向变化关系. 从而进一步揭示了中国大陆活动地块构造及其块体运动特征，以及块体边界带的构造变形对强震的控制作用.     

Preliminary results on kinematic model of tectonic blocks derived from high precision GPS observations in Southwest China

ＰｒｅｌｉｍｉｎａｒｙｒｅｓｕｌｔｓｏｎｋｉｎｅｍａｔｉｃｍｏｄｅｌｏｆｔｅｃｔｏｎｉｃｂｌｏｃｋｓｄｅｒｉｖｅｄｆｒｏｍｈｉｇｈｐｒｅｃｉｓｉｏｎＧＰＳｏｂｓｅｒｖａｔｉｏｎｓｉｎＳｏｕｔｈｗｅｓｔＣｈｉｎａＬＩＲＥＮＨＵＡＮＧ１）（黄立人）...     

Preliminary division of active block boundary in Chinese mainland based on recent vertical crustal movement

IntroductionSituated in the southeastern part of Eurasia Plate and surrounded by the India Plate, Eurasia Plate, Pacific Plate and Philippine Sea Plate, Chinese mainland especially the area of Qinghai-Xizang (Qingzang) Plateau and the south-north tectonic zone is the area with the most intensive neotectonic deformation. The main component of tectonic activity in Chinese mainland is active blocks. Therefore, it is quite important to study active blocks in the research of tectonic activit…     

PROGRESS IN APPLICATION OF GNSS TO DIVISION OF ACTIVE TECTONIC BLOCKS IN CONTINENTAL CHINA

Chinese scientists proposed that large earthquakes that occurred in mainland China are controlled by the movement and deformation of active tectonic blocks. This scientific hypothesis explains zoned phenomenon of seismicity in space. The active tectonic blocks are intense active terranes formed in late Cenozoic and late Quaternary, and the tectonic activity of block boundaries is the intensest. Global Navigation Satellite System(GNSS)has advantages of high spatio-temporal resolution, broad coverage, and high accuracy, and is utilized to monitor contemporary crustal deformation. High accuracy and resolution of GNSS velocity field within mainland China and vicinities provided by previous studies clearly demonstrate that different active tectonic blocks behave as different patterns of movement and deformation, and block interaction boundaries have intense tectonic deformation. The paper firstly introduces the GPS networks operated by the Crustal Movement Observation Network of China(CMONOC)since 1999, and GNSS data processing methods, including GAMIT, BERNESE and GIPSY/OASIS, and discusses the advantages of using South China block as a regional reference frame for GNSS velocity field, then proposes three strategies of block division, F-test, quasi-accurate detection(QUAD), and clustering analysis. Furthermore, we introduce rigid and non-rigid block motions. Rigid block motion can be denoted by translation and rotation, while non-rigid block motion can be described by rigid motion and internal strain deformation. Internal strain deformation can be divided into uniform and linear strains. We also review the usage of F-test to distinguish whether the block acts as rigid deformation or not. In addition, combining with recent GNSS velocity results, we elaborate the characteristics of present movement of rigid block, such as the South China, Tarim, Ordos, Alashan, and Northeast China, and that of non-rigid block, such as the Tibetan plateau, Tian Shan, and North China plain. Especially, the Tibetan plateau and Tian Shan seem to deform continuously with significant internal deformation. In order to enrich and perfect the active tectonic block hypothesis, we should carefully design dense GNSS networks in inner blocks and block boundaries, optimize utilizing other space geodesy technologies such as InSAR, and strengthen combining study of geodesy, seismogeology and geophysics. Through systematic summary, this paper is very useful to employing GNSS to investigate characteristics of block movement and dynamics of large earthquakes happening in block interaction boundaries.     

Horizontal crustal movement in Chinese mainland from 1999 to 2001

Introduction In the Crustal Movement Observation Network of China (CMONOC) there are 25 fiducialstations, 56 basic stations and 1 000 regional stations. They are scattered on 10 major blocks inChinese mainland with high density of observation stations on the blocks of high seismic activityin the regional networks. 10 major blocks or regions (they will be referred to as blocks in the paper,a letter is used as a symbol for each block) were divided during the design of the regionalnetwo…     

日本内陆地震活动的迁移与扩散

本文研究了日本内陆及其外围海域发生大地震后的地震活动迁移现象。在所研究的6个震例中,一个共同的特点是,地震活动的迁移总是沿着地壳内的活动地质构造带发生。有时可以根据地震活动的迁移来进一步确定活动构造带的存在。把板块边缘地区的地震活动类比为沿着力学偶合平面迁移和扩散,我们可以认为,岛上的活动构造带对应着地壳块体的力学相互作用边界。地震迁移的形式可能不只一种。在我们所研究的震例中发现了以下特征:地震迁移速度约为几km/年;大地震震源区之间存在着地震空区;在每一条地震带上有一定的地震活动周期。地震迁移的一种可能机制是:由于地壳块体的相对运动,在其边界上的凹凸不平区造成了构造应力集中,这些凹凸不平区相继地发生破裂,形成了地震迁移。     

基于GPS观测的地壳水平运动划分活动地块的试验

本文分析了板内块体与板块运动的差别,提出以Ｂｕｒｓａ公式作为板内块体的运动学模型,并据此提出了划分板内活动地块的方法。根据华北ＧＰＳ网１９９５、１９９６和１９９９年的３期观测成果,用本文提出的数学模型和方法,将华北北 剖地区划分为８个小块体。本文用地壳水平运动划分的结果与用本区地壳垂直运动划分的结果在是体旧一致或相近的。本文的划分结果与新构造运动也基本一致,本区活动块体的现今运动是新构造的继承和发     

Movement and strain conditions of active blocks in the Chinese mainland

The definition of active block is given from the angles of crustal deformation and strain. The movement and strain parameters of active blocks are estimated according to the unified velocity field composed of the velocities at 1598 GPS stations obtained from GPS measurements carried out in the past years in the Chinese mainland and the surrounding areas. The movement and strain conditions of the blocks are analyzed. The active blocks in the Chinese mainland have a consistent E-trending movement component, but its N and S components are not consistent. The blocks in the western part have a consistent N-trending movement and the blocks in the eastern part have a consistent S-trending movement. In the area to the east of 90°E, that is the area from Himalayas block towards NE, the movement direction of the blocks rotates clockwisely and the movement rates of the blocks are different. Generally, the movement rate is large in the west and south and small in the east and north with a difference of 3 to 4 times between the rates in the west and east. The distributions of principal compressive strain directions of the blocks are also different. The principal strain of the blocks located to the west of 90oE is basically in the SN direction, the principal compressive strain of the blocks in the northeastern part of Qingzang plateau is roughly in the NE direction and the direction of principal compressive strain of the blocks in the southeastern part of Qingzang plateau rounds clockwisely the east end of Himalayas structure. In addition, the principal strain and shear strain rates of the blocks are also different. The Himalayas and Tianshan blocks have the largest principal compressive strain and the maximum shear strain rate. Then, Lhasa, Qiangtang, Southwest Yunnan (SW Yunnan), Qilian and Sichuan-Yunan (Chuan-Dian) blocks followed. The strain rate of the blocks in the eastern part is smaller. The estimation based on the stain condition indicates that Himalayas block is still the area with the most intensive tectonic activity and it shortens in the NS direction at the rate of 15.2±1.5 mm/a. Tianshan block ranks the second and it shortens in the NS direction at the rate of 10.1±0.9 mm/a. At present, the two blocks are still uprising. It can be seen from superficial strain that the Chinese mainland is predominated by superficial expansion. Almost the total area in the eastern part of the Chinese mainland is expanded, while in the western part, the superficial compression and expansion are alternatively distributed from the south to the north. In the Chinese mainland, most EW-trending or proximate EW-trending faults have the left-lateral or left-lateral strike-slip relative movements along both sides, and most NS-trending faults have the right-lateral or right-lateral strike-slip relative movements along both sides. According to the data from GPS measurements the left-lateral strike-slip rate is 4.8±1.3 mm/a in the central part of Altun fault and 9.8±2.2 mm/a on Xianshuihe fault. The movement of the fault along the block boundary has provided the condition for block movement, so the movements of the block and its boundary are consistent, but the movement levels of the blocks are different. The statistic results indicate that the relative movement between most blocks is quite significant, which proves that active blocks exist. Himalayas, Tianshan, Qiangtang and SW Yunnan blocks have the most intensive movement; China-Mongolia, China-Korea (China-Korea), Alxa and South China blocks are rather stable. The mutual action of India, Pacific and Philippine Sea plates versus Eurasia plate is the principal driving force to the block movement in the Chinese mainland. Under the NNE-trending intensive press from India plate, the crustal matter of Qingzang plateau moves to the NNE and NE directions, then is hindered by the blocks located in the northern, northeastern and eastern parts. The crustal matter moves towards the Indian Ocean by the southeastern part of the plateau.     

Current crustal movement in Chinese mainland

The quantification of tectonic deformation in the Eastern and Central Asia is of great significance for the study on global plate motion and lithospheric dynamics. In the past four years, the velocity field of horizontal crustal movement for the Chinese mainland has been established for the first time thanks to the intensified GPS measure-ments and its improved accuracy. The velocity field derived from GPS measurements delineates the patterns of tectonic deformation in the Chinese mainland in the unprecedented detail, and thus reveals the new features of the ongoing tectonic process resulted from the collision of Indian plate to Eurasian plate. Meanwhile, the surface offset induced by two strong earthquakes occurred in Chinese mainland was sampled precisely using InSAR technique.     

中国大陆现今地壳运动研究

GPS结果十分清晰地刻画出中国大陆地区块体运动及内部变形特征，提供了认识印度欧亚碰撞引起的活动构造的新视角．本文回顾了4年来中国学者在利用GPS研究现今地壳运动方面所取得的成就，以及在利用InSAR技术研究强震破裂方面的进展情况．这些研究成果，标志着中国大陆构造变形的定量化研究进入了一个新阶段.      

强震造成的活动地块地壳形变差异探讨

20 0 1年 11月 14日发生在昆仑山口西的 8 1级地震 ,在地表产生了长度大于 35 0km的破裂带 ,最大水平位移 6m左右 ,为左旋走滑断层。在昆仑山口西 8 1级地震周围不同活动地块内不同构造部位布设的GPS基准站对地震的响应存在明显的差异。其中位于柴达木活动地块内部的德令哈基准站在地震的当天观测到 7 5mm的同震位移 ,位于川滇活动地块西南边界带的下关基准站在震后 3d发生了 6 8mm以上的明显位移 ,而位于同一地块内部的昆明基准站和位于祁连山活动地块内的西宁基准站、位于拉萨活动地块内的拉萨基准站震时和震后都没有产生明显的位移。GPS基准站的观测资料表明 ,强震所处的活动地块和其相邻活动地块对强震有明显的响应 ,如果相隔一活动地块 ,则受强震的影响较小 ;在活动地块内 ,活动强烈的边界带或其它活动较强的部位对强震引起的地壳形变的响应明显大于活动强度较弱的部位 ;强震对相邻活动地块影响的差异 ,主要与强震所处活动地块运动时对其产生的作用方式的差异有关     

Horizontal crustal movement in Chinese mainland from 1999 to 2001

The paper introduces the horizontal crustal movement obtained from GPS observations in the regional networks (including the basic network and the fiducial network) of the Crustal Movement Observation Network of China (CMONOC) carried out in 1999 and 2001. This paper is characterized by the acquisition of the horizontal displacement velocities during the period from 1999 to 2001 at the observation stations in the regional networks with datum definition of a group of stable stations with small mutual displacements in east China. Based on the most detailed map of horizontal crustal movement in Chinese mainland, the division of blocks, their displacements and deformations are studied. An approach to analysis of the intensity of the horizontal crustal deformation is proposed. The general characteristics of the recent horizontal crustal movement in Chinese mainland and that before the Kunlunshan earthquake of M=8.1 on November 14, 2001 are analyzed. Foundation item: The National Development and Programming Project for Key Basic Research (95-13-03-07).     

Movement and strain conditions of active blocks in the Chinese mainland

The definition of active block is given from the angles of crustal deformation and strain. The movement and strain parameters of active blocks are estimated according to the unified velocity field composed of the velocities at 1598 GPS stations obtained from GPS measurements carried out in the past years in the Chinese mainland and the surrounding areas. The movement and strain conditions of the blocks are analyzed. The active blocks in the Chinese mainland have a consistent E-trending movement component, but its N and S components are not consistent. The blocks in the western part have a consistent N-trending movement and the blocks in the eastern part have a consistent S-trending movement. In the area to the east of 90°E, that is the area from Himalayas block towards NE, the movement direction of the blocks rotates clockwisely and the movement rates of the blocks are different. Generally, the movement rate is large in the west and south and small in the east and north with a difference of 3 to 4 times between the rates in the west and east. The distributions of principal compressive strain directions of the blocks are also different. The principal strain of the blocks located to the west of 90°E is basically in the SN direction, the principal compressive strain of the blocks in the northeastern part of Qingzang plateau is roughly in the NE direction and the direction of principal compressive strain of the blocks in the southeastern part of Qingzang plateau rounds clockwisely the east end of Himalayas structure. In addition, the principal strain and shear strain rates of the blocks are also different. The Himalayas and Tianshan blocks have the largest principal compressive strain and the maximum shear strain rate. Then, Lhasa, Qiangtang, Southwest Yunnan (SW Yunnan), Qilian and Sichuan-Yunan (Chuan-Dian) blocks followed. The strain rate of the blocks in the eastern part is smaller. The estimation based on the stain condition indicates that Himalayas block is still the area with the most intensive tectonic activity and it shortens in the NS direction at the rate of 15.2 ± 1.5 mm/a. Tianshan block ranks the second and it shortens in the NS direction at the rate of 10.1 ± 0.9 mm/a. At present, the two blocks are still uprising. It can be seen from superficial strain that the Chinese mainland is predominated by superficial expansion. Almost the total area in the eastern part of the Chinese mainland is expanded, while in the western part, the superficial compression and expansion are alternatively distributed from the south to the north. In the Chinese mainland, most EW-trending or proximate EW-trending faults have the left-lateral or left-lateral strike-slip relative movements along both sides, and most NS-trending faults have the right-lateral or right-lateral strike-slip relative movements along both sides. According to the data from GPS measurements the left-lateral strike-slip rate is 4.8 ± 1.3 mm/a in the central part of Altun fault and 9.8 ± 2.2 mm/a on Xianshuihe fault. The movement of the fault along the block boundary has provided the condition for block movement, so the movements of the block and its boundary are consistent, but the movement levels of the blocks are different. The statistic results indicate that the relative movement between most blocks is quite significant, which proves that active blocks exist. Himalayas, Tianshan, Qiangtang and SW Yunnan blocks have the most intensive movement; China-Mongolia, China-Korea (China-Korea), Alxa and South China blocks are rather stable. The mutual action of India, Pacific and Philippine Sea plates versus Eurasia plate is the principal driving force to the block movement in the Chinese mainland. Under the NNE-trending intensive press from India plate, the crustal matter of Qingzang plateau moves to the NNE and NE directions, then is hindered by the blocks located in the northern, northeastern and eastern parts. The crustal matter moves towards the Indian Ocean by the southeastern part of the plateau.     

Active tectonic blocks and strong earthquakes in the continent of China

The primary pattern of the late Cenozoic to the present tectonic deformation of China is characterized by relative movements and interactions of tectonic blocks. Active tectonic blocks are geological units that have been separated from each other by active tectonic zones. Boundaries between blocks are the highest gradient of differential movement. Most of tectonic activity occurs on boundaries of the blocks. Earthquakes are results of abrupt releases of accumulated strain energy that reaches the threshold of strength of the earth's crust. Boundaries of tectonic blocks are the locations of most discontinuous deformation and highest gradient of stress accumulation, thus are the most likely places for strain energy accumulation and releases, and in turn, devastating earthquakes. Almost all earthquakes of magnitude greater than 8 and 80%-90% of earthquakes of magnitude over 7 occur along boundaries of active tectonic blocks. This fact indicates that differential movements and interactions of active tectonic blocks are the primary mechanism for the occurrences of devastating earthquakes.     

Active tectonic blocks and strong earthquakes in the continent of China

The primary pattern of the late Cenozoic to the present tectonic deformation of China is characterized by relative movements and interactions of tectonic blocks. Active tectonic blocks are geological units that have been separated from each other by active tectonic zones. Boundaries between blocks are the highest gradient of differential movement. Most of tectonic activity occurs on boundaries of the blocks. Earthquakes are results of abrupt releases of accumulated strain energy that reaches the threshold of strength of the earth’s crust. Boundaries of tectonic blocks are the locations of most discontinuous deformation and highest gradient of stress accumulation, thus are the most likely places for strain energy accumulation and releases, and in turn, devastating earthquakes. Almost all earthquakes of magnitude greater than 8 and 80%–90% of earthquakes of magnitude over 7 occur along boundaries of active tectonic blocks. This fact indicates that differential movements and interactions of active tectonic blocks are the primary mechanism for the occurrences of devastating earthquakes.     

华北地区GPS形变测量结果及其地震地质意义

简要介绍了华北地区ＧＰＳ形变监测网１９９５～１９９６年两次观测概况,利用伯尔尼软件进行数据处理的主要过程、水平形变计算与应变分析的方法和结果及垂直形变的结果。分析了ＧＰＳ成果的地震地质意义,认为ＧＰＳ观测到的水平形变可能反映了上地壳层块构造活动的某些特征     

陕甘宁青地区块体交接带上大地垂直形变演化特征与块体运动

分析了关中、银川、西海固及民乐４个地区褶断隆起与断陷盆地组合构造带上的大地垂直形变演化特征．结果表明，１９７７年前后，鄂尔多斯西侧和南侧的大地垂直形变场变化与大华北应力场的消长过程密切相关．１９８３年以后，青藏块体边缘的民乐、西海固及银川地区继承性构造形变逐渐增大，在此背景下，１９８８年以来在亚板块内部及其边缘地区发生了一系列强震．从现今垂直形变场显示的时空结构来看，青藏亚板块和华北亚板块对交接带上的构造形变交替起着主导作用，并产生了不同的形变特征．