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…     

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).     

General characteristics of the recent horizontal crustal movement in Chinese mainland

1 Introduction of GPS observation dataThe Crustal Movement Observation Network of China (CMONOC) is a major scientific project in China organized by China Seismological Bureau and paticipated by the Bureau of Surveying and Mapping of the General Staff, the Chinese Academy of Sciences and the National Bureau of Surveying and Mapping. Based on the observation data of 25 fiducial stations and 56 basic stations in CMONOC (Figure 1 and Table 1), collected from August 26 to September…     

GPS技术监测地壳运动的新进展

回顾了GPS观测技术应用于地壳运动与形变中的相关理论与方法,重点介绍了水平应变的计算方法与描述地壳运动与形变场的各种数学物理方法,讨论了提取地壳运动与形变信息过程中存在的问题.     

Crustal block rotations in Chinese mainland revealed by GPS measurements

We simulate GPS horizontal velocity field in terms of rotations of crustal blocks to describe deformation behavior of the Chinese mainland and its neighboring areas.31 crustal blocks are bounded primarily by~30 Quaternary faults with distinct geometries and variable long-term rates of<20 mm/a,and 1 683 GPS velocities were determined from decade-long observations mostly with an averaged uncertainty of 1?2 mm/a.We define GPS velocity at a site by the combination of motion of rigid block and elastic strain ind...     

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 ;…     

Recent crustal horizontal movement in the Chinese mainland

IntroductionSupportedbytheNationaIClimbingProject"RecentCrustalMovementandGeodynamicResearch",acrustalmovementmonitoringnetworkdistributedinChinesemainlandhasbeenmeasuredfortWotimesinl994andl996.Thenetconsistsof22stationsthatarelocatedonsev-eralmajortectonicblocksinChinesemainland.ExceptNanchongstationwhichwasdestroyedatsometimebetWeenl994and1996andre-settledinl996,alltheother2lstationswereoccupiedfortwotimes.BasedontheresuItSobtainedfromcarefulpre-processingofGPSobservations,therecent…     

Intermediate to Long-term Estimation of Strong Earthquake Risk Areas in the Chinese Mainland Based on Geodesic Measurements

Based on previous research results, present-day crustal deformation and gravity fields in the Chinese mainland are analyzed using the GPS data, leveling, gravity and cross-fault deformations. We analyzed strain accumulation of the major faults, and identified locked or high strain accumulation segments. Combining the effects of large earthquakes in the study area, the long-term (decade) probability of large earthquakes in the Chinese mainland is estimated.     

张家口—渤海断裂带分段运动变形特征分析

利用张家口—渤海断裂带(张渤带)及其邻区1999—2007年的GPS观测数据, 研究了该区域现今地壳水平速度场特征。 运用最小二乘配置方法获得应变率场的空间分布特征, 根据区域地壳主应变率、 面膨胀率和最大剪切应变率等形变场的空间变化, 分析了张渤带各分段的形变特征。 结果表明: 相对于欧亚框架, 研究区内GPS速度场以SE方向运动为主; 应变场以NE方向的主压应变为主, 伴随着近NW方向的张性应变; 整个张渤带及其邻区的高剪切变形区主要位于河北香河、 文安以及唐山等三个地区。 利用跨断层GPS剖面分析得到张渤带以左旋走滑为主, 兼有挤压运动。 华北平原块体和燕山块体的相对运动是张渤带左旋走滑的直接动力来源, 而印度板块与欧亚板块碰撞后继续向北的推挤作用则是张渤带运动变形的根本动力来源, 太平洋板块的作用相对较弱。     

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.     

关于2001年昆仑山8.1级大地震前后中国大陆地壳水平运动的讨论s

中国地壳运动观测网络基准网GPS连续观测,获得了2001年11月14日昆仑山8.1级大地震前后中国大陆,特别是西部地区的地壳水平运动信息．以东部长期相互间相对水平位移很小的几个站组成的一组稳定点作为基准, 据此获得水平位移分量时间序列．2000年11月上旬起中国西部的GPS基准站开始出现显著的异常位移,此后在云南及四川发生多次6级左右的地震．自2001年4月中旬开始,中国西部GPS基准站向北的水平位移速率明显减小,甚至反向,临震前及震后略有恢复,但震后向北的水平位移速率仍减小,并有明显的向西运动．近几年中国大陆西部（相对东部）的地壳运动过程表明,印度板块的向北挤压是昆仑山8.1级大地震的主要力源,大地震释放了大量的能量,印度板块对中国大陆的作用力明显降低,大震后至2002年底中国大陆的地震活动也明显降低．     

Horizontal crustal movement in Chinese mainland before and after the great Kunlun Mountain <Emphasis Type="Italic">M</Emphasis>=8.1 earthquake in 2001

The continuous GPS observation at the fiducial stations in the Crustal Movement Observation Network of China (CMONOC) recorded the crustal movement of Chinese mainland before and after the great Kunlun Mountain earthquake of M=8.1 on November 14, 2001, especially the horizontal crustal movement in the western part of China. Based on the datum defined by a group of stable stations with small mutual horizontal displacements for a few years, the time series of horizontal displacements at fiducial stations were obtained. Significant anomalous horizontal displacements had appeared at the fiducial stations in the western part of China since early November 2000 and several earthquakes with the magnitudes about 6.0 had occurred in Yunnan and Sichuan Provinces. The northward components of the horizontal displacement at the fiducial stations in west China had decreased significantly and even changed in the opposite sense since mid April 2001. After the earthquake, the northward displacements still decreased and there were significant westward displacements. The process of the crustal movement in the western part of Chinese mainland (in reference to east China) suggests that the main force source for this earthquake came from the northward pushing of the Indian plate. The great earthquake released a large amount of energy, as a result, the action applied by the Indian plate to Chinese mainland diminished significantly and after the great earthquake, the seismic activity in Chinese mainland decreased considerably until the end of 2002.     

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.     

Horizontal crustal movement in Chinese mainland before and after the great Kunlun Mountain M=8.1 earthquake in 2001

Introduction The great Kunlun Mountain earthquake occurred on November 14, 2001 on the border be-tween Xinjiang and Qinghai in west China (36.2N, 90.9E). It was the largest earthquake oc-curred in Chinese mainland in the last 50 years. The Crustal Movement Observation Network of China (CMONOC) established in 1998 mainly for the purpose of earthquake prediction with only 25 fiducial stations for continuous GPS observations, has recorded the precious information of the crustal movement …     

张家口-渤海断裂带分段运动变形特征分析

We have collected GPS data in the period of 1999-2007 from the Crustal Motion Observation Network of China along the Zhangjiakou-Bohai fault and its adjacent regions to study the characteristics of present-day crustal horizontal motion velocities in the research zone.Strain rate components are computed in the spheric coordinate system by the least square collocation method.According to the spatial distribution of the principal strain rate,dilation rate and maximum shear strain rate derived from GPS measurements,this paper analyses the deformation of the subordinary faults of the Zhangjiakou-Bohai fault.The principal compression strain rates are apparently greater than the principal extension strain rates.The larger shear strain rate is mainly in and around the Xianghe,Wenan and Tangshan areas in Hebei Province.According to the profiles across different segments of the Zhangjiakou-Bohai fault,the three segments glong the Zhangjiakou-Bohai fault show an obviously left-lateal strike-slip and compression characteristics.By analysis of the motion characteristics of the blocks,e.g.the Yanshan block,North China Plain block,Ordos block,and Ludong-Huanghai block in and around the North China region,this paper speculates that the dynamics of the motion styles of Zhangjiakou-Bohai fault may directly come from the relative movement between the Yanshan block and the North China plain block,and the ultimate dynamics may be the results of the collison between Indian plate and Eurasian plate,and the persistent northeastward extrusion of the Indian plate.     

基于GPS获得的中国大陆现今地壳运动速度场

利用国家重大科学工程“中国地壳运动观测网络”1999至2011年底的全部GPS观测资料,采用统一的数据处理策略和最新的地球物理模型,分别获取了中国大陆相对于全球ITRF2005参考框架和欧亚板块的现今地壳水平运动速度场。通过速度场分析,给出了中国大陆地壳运动的大背景和基本特征,为地震预测、地球动力学等相关学科的研究提供了基础资料。     

Horizontal crustal movement in Chinese mainland before and after the great Kunlun Mountain M =8.1 earthquake in 2001

The continuous GPS observation at the fiducial stations in the Crustal Movement Observation Network of China (CMONOC) recorded the crustal movement of Chinese mainland before and after the great Kunlun Mountain earthquake of M=8.1 on November 14, 2001, especially the horizontal crustal movement in the western part of China. Based on the datum defined by a group of stable stations with small mutual horizontal displacements for a few years, the time series of horizontal displacements at fiducial stations were obtained. Significant anomalous horizontal displacements had appeared at the fiducial stations in the western part of China since early November 2000 and several earthquakes with the magnitudes about 6.0 had occurred in Yunnan and Sichuan Provinces. The northward components of the horizontal displacement at the fiducial stations in west China had decreased significantly and even changed in the opposite sense since mid April 2001. After the earthquake, the northward displacements still decreased and there were significant westward displacements. The process of the crustal movement in the western part of Chinese mainland (in reference to east China) suggests that the main force source for this earthquake came from the northward pushing of the Indian plate. The great earthquake released a large amount of energy, as a result, the action applied by the Indian plate to Chinese mainland diminished significantly and after the great earthquake, the seismic activity in Chinese mainland decreased considerably until the end of 2002. Foundation item: The National Development and Programming Project for Key Basic Research (95-13-03-07).     

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.     

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.