滨海附近地区GPS和断层形变与地震关系研究

简要介绍了环勃海及华北部分地区跨断层形变资料的分析结果,同时介绍了１９９２年至１９９５年首都圈两期ＧＰＳ测量资料处理分析的初步结果。通过比较,二者所显示的地壳活动趋势存在性质上的差异,主要是因观测时段的不一致而引起;在同时段资料的对比分析中,因测点和断层空间分布差异的存在,有４４．８％的流动资料难以判定其与ＧＰＳ资料的一致性,但在可判定的３３项资料中,有８９％是一致的,证明二者从不同的侧面反映了近     

地震位移场和板内地震震源力学性质的讨论

本文推导了各类点源和线源（压性、张性、压扭性、张扭性、单力偶和双力偶）的理论地震位移场公式, 讨论了板内地震的震源力学性质.根据实测地震位移场、建筑物破坏和倒塌的优势方向等近场资料与理论结果对比, 作者认为, 1966年邢台地震震源机制符合于张性断裂的模型;1966年东川地震震源机制符合于压扭性断裂的模型.根据理论公式和实际位移资料, 给出了邢台地震的地震矩 M0为6.51026达因厘米, 应力降△为39巴.最后指出大地震的震源力学机制反映了该区域长期构造应力作用的状态, 认为双力偶（剪切位错）不一定是板内地震震源机制的最合适的、唯一的模型.      

华北地区近期地壳水平运动与应力应变场特征

利用华北GPS监测网 1 992年、1 995年、1 996年的观测资料 ,应用最小二乘配置给出了华北地区相对水平位移场、应变场的分布图像 .经初步研究表明 :华北地区 1 992-1 995年间的水平位移和应变场表现为整体性不均匀的压性运动 ,1 995- 1 996年测区东部仍以水平压性运动为主 ,但测区西部则主要表现为张性运动 .水平运动 （方向、大小 ）发生显著变化和应变高值区的地带主要位于块体边界带和主要断裂带附近 .燕山断块南边界的北东向断裂存在着较显著的左旋运动 .区内最大剪应变、面膨胀的高值区在天津、北京、唐山一带 .结合非连续变形数值分析方法 （DDA）初步分析认为 ,1 992- 1 995年GPS观测结果显示的华北地区存在东、西部构造应力作用的明显差别 ,华北东部以东西向压应力作用为主 ,而西部的南北向构造应力作用又明显大于东部 .     

青藏块体东北缘近期水平运动与变形

利用青藏块体东北缘地区13、1年GPS观测资料，给出了本区地壳水平运动速度场及视应变场分布图，提出了由位移观测值直接求解块体旋转和变形参数的方法，初步研究了本区构造块体运动与变形特征.结果表明：①本区存在整体性向东-东南方的运动(速率约mm/a)；②南部的甘肃-青海块体的运动较快，而北部的阿拉善块体的运动较慢，二者运动速率相差近6mm/a，祁连-海原断裂带左旋走滑运动显著.③自西向东存在北北东-北东东向压性运动；④阿拉善块体、甘肃-青海块体内部存在北西西向张性变形，阿拉善块体的整体张性变形更显著，鄂尔多斯块体西侧的块体交接地带为压性运动.     

Preliminary Study on the Horizontal Crustal Deformation in Chinese Continent

In the paper, the current strain field and stress field in Chinese continent have been discussedbased on the processed data from two GPS campaigns of national GPS network carried out inthe years of 1994 and 1996. With a principal compressional strain direction of NNE, thewestern and castern parts of Qinghai-Xizang subplate are dominated by extensional straiu andthe central Part by compressional strain. Along the southwestern segment of southeastern partof Qinghai-Xizang subplate, i. e. Yunnan area, the princiPal compressional strain direction isNW and the compressional strain is equivalent to the extensional strain in magnitude. Theprincipal compressional strain of Xinjiang subplate is mainly NNE and NE with a difference inthe strain magnitude. The principal compressional strain in North China subplate is quite effective in NE and nearly EW directions with differences along some segments. However, thecompressional strain is corresponding to the extensional strain in magnitude in most areas. Theprincipal     

太行山麓淇县—新乡—焦作地区现今构造应力状态与地震活动关系

本文根据现今断裂活动特征、地下水活动、震源机制等资料初步研究了河南省淇县—新乡一焦作地区的现今构造应力状态。并结合有限元分析计算,初步探讨了应力状态与地震的关系。最后指出了该区有可能发生中强地震的构造部位     

8.1级震后青藏块体东北部水平形变态势与地震有序活动研究

青藏块体东北部2003年最新GPS复测揭示：昆仑山口西8．1级地震后本区水平运动变形较前变异显,以甘青块体西部出现的与NE向挤压背景相反的张性运动变形为主要标志,且区域总体应变幅度增大。结合地震有序活动分析认为：本区目前的水平运动变形态势,与8．1级大震及随后青藏块体中西部发育的NE向中强以上地震条带在较短时间内释放了大量的压应变,使得青藏块体北部区域NE向推挤的应力场失衡(西侧的区域应力场强度衰减、东侧的应力场增强)密切相关;因而青藏块体北部大区域应力场趋于平衡过程将有利于块体东北边缘应力应变加速积累和破裂错动。     

长江带现代地震构造应力场分布特征

根据长江带76个地震震源机制解与17个小震综合断层面解的结果统计分析,得到该带地震应力场主应力方向的优势分布。表明该带处于北东东—南东东向挤压和北北西—近南北向引张的构造应力作用之中。在力的性质上,该带水平张应力高于水平压应力,斜向压应力又高于斜向张应力,与华北地区比较,主应力方向相对向东南方向偏转,该带水平力和斜力所占比例均高于华北地区,同时讨论了该带中三个分区的现代构造应力场分布及它们的力源关系。     

Current Activity Characteristics of the Fault Zone Along the Northern Margin of West Qinling Range Revealed by GPS Measurementl

The fault zone along the northern margin of West Qinling Range is a major active fault zonein the key seismic monitoring area in the southeastern part of Gansu Province.In order tostudy the current activity characteristics of this fault,GPS monitoring network has beenarranged along both sides of the fault and 3 measurements have been made from 1996 to1998.The result indicates that obvious differential movement exists along the north and southsides of the fault and the eastward movement on the south side is 3.8mm/a larger than thaton the north side.In the GPS network,the shortened side is generally in the trend of EW andthe extended side is basically NW to SE.The principal compressional stress trend in this areais about EW and the sinistral motion is obvious in the eastern part of the fault(nearWushan).The measured results also indicate that the displacement rate has decreased by50% and the compressional strain has increased by 100% as compared the data of 1997～1998 with those of 1996～1997,which shows t     

中国大陆及周边地区现代岩石圈演化动力学模拟

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.     

Progress in technology for the 2005 height determination of Qomolangma Feng (Mt. Everest)

Qomolangma Feng——Mt. Everest (QF in shorter) is located in the east part of the China-Nepal boundary. QF is the highest mountain in China, also in the world. It lies in the collision zone along the boundary of Eurasian and Indian plates. It is one of focuses in geo- sciences study[1―7]. The northern slope area of the QF (QF area in shorter) is in Tibet, China, and the altitude of snow line in the QF area is around 6000 m. Spring in the QF area is March, April and May every year, a…     

祁连山构造带红外测距观测揭示的应变强度时空演变特征

利用截止2007年最新的、跨祁连山构造带红外测距观测资料，结合区域GPS观测所得形变背景，获取跨断层水平应变强度时空演变特征，分析其与2002年玉门Ms5．9级、2003年民乐Ms6．1．级等地震孕育一发生过程的关系。结果表明：①震前数月至1年左右，震中所在断层段（或整个构造带）应变加速或相对其它断层段显著，压性为主；其内一定数量场地最大剪应变强度明显“增强”或面应变强度“压性增强”（至绝对值2．0左右及以上），震后减弱或呈现张性转折。②2004年下半年以来祁连山构造带总体恢复压性变化为主的应力场状态，反映一定程度应力应变积累特性；2007年构造带西段压性应变明显增强。     

Characteristics of crustal strain associated with M =6.4 Baotou earthquake in 1996

Based on the horizontal crustal strain derived from GPS data and the rate accumulation intensity calculated from across-fault vertical deformation, the strain characteristics in the periods of 1992–1995, 1995–1996 and 1996–1999 in Baotou-Datong area is studied in the paper. From the comparison between the crustal strains before and after the M=6.4 Baotou earthquake occurred on May 3, 1996, it is considered that the high-magnitude area with predominant compressive strain might be the seismogenic zone for a coming strong earthquake. The area with the simultaneous higher surface strain, principal compressive strain, shear strain and tendency accumulation might be the place with higher risk of strong earthquakes. Generally, the area with low strain and predominant tensile strain might have a small possibility for strong earthquake development, which belongs to a stable area. The evolution of horizontal strain obtained from GPS measurements carried out in Baotou-Datong area in the period of 1992–1999 reflects the total developing and ending processes of the seismic episode from 1996 to 1998. The area with high and predominant compressive strain and the strain gradient zone can be considered as one of the indicators for determining the strong earthquake risk area in the future. Foundation item: State Key Basic Research Development and Programming Project (G19998040700) and State Natural Science Foundation of China (40174029).     

Determination of active units with different kinematic property and their activity pattern in North China based on the data from GPS remeasurements

Based on the high-accuracy data obtained from the GPS measurements carried out in 1992, 1995 and 1996, the isochronous active units with different kinematic property inside the North China area have been distinguished, 4 active units and 1 transition zone with distinct differential movement have been determined. They are Ordos-Yinshan unit, Yanshan unit, Shanxi-Hebei-Shandong (Jin-Ji-Lu) unit, Jiaodong-Liaoning-Shandong (Jiao-Liao-Lu) unit and Yanshan-Hebei (Yan-Ji) transition zone. The relative movements among the neighboring units in this period have been given. 1 The compressive movement between Ordos-Yinshan unit and Yanshan unit is not obvious with an amount of 0.4±1.3 mm/a. 2 Jin-Ji-Lu unit moves E40°S off the Ordos-Yinshan unit and the magnitude is 4.4±1.0 mm/a. 3 Relative to the Yan-Ji transition zone of differential movement, Yanshan unit shifts W38°N with a value of 2.4±1.3 mm/a and Jin-Ji-Lu unit moves eastward 35° by south with an amount of 2.3±0.9 mm/a. 4 Jin-Ji-Lu unit has a tensional left-lateral movement of 4.7±1.4 mm/a in the direction of E37°S relative to Yanshan unit. 5 Some area near Tanlu belt which is located in the southern part of Jin-Ji-Lu block has a southward movement 14° by west with a magnitude of 1.5±1.1 mm/a off the Jin-Ji-Lu unit. 6 Relative to Jin-Ji-Lu unit, Jiao-Liao-Lu unit has a trend of clockwise movement with a tensional right-lateral motion at the north end which neighbors Yanshan unit and a compressive motion at the south end. It should be noted that the errors given in the paper are obtained based on the divergence among the displacements of the sites in the unit, rather than the value calculated from the displacement error of the sites. The analyzed results indicate that: 1 Shanxi tectonic zone and Yan-Ji transition zone are the major tectonic active zones to show the frame and magnitude of interior relative movement in North China area, and others are the secondary tectonic active zones; 2 The complete horizontal deformation in the North China area is not homogeneous nor successive; 3 The kinetic model of North China area might be "mantle dragging plus boundary coupling". Foundation item: The National Key Basic Research Project Mechanism and Prediction of Continental Earthquakes (G1998040700).     

Characteristics of crustal strain associated with M=6.4 Baotou earthquake in 1996

Introduction Since the 1990s, GPS technique has been widely used in the crustal deformation measurement in China, which has promoted the development in geodynamic study. More and more attentions have been paid to GPS data in the study on crustal movement by the vast geoscientists and many significant results have been achieved (HUANG, et al, 1996; LI, et al, 1998; GUO, 2000). The North China is one of the areas to establish GPS monitoring networks earlier in China. After the establis…     

Characteristics of crustal strain associated with <Emphasis Type="Italic">M</Emphasis>=6.4 Baotou earthquake in 1996

Based on the horizontal crustal strain derived from GPS data and the rate accumulation intensity calculated from across-fault vertical deformation, the strain characteristics in the periods of 1992–1995, 1995–1996 and 1996–1999 in Baotou-Datong area is studied in the paper. From the comparison between the crustal strains before and after the M=6.4 Baotou earthquake occurred on May 3, 1996, it is considered that the high-magnitude area with predominant compressive strain might be the seismogenic zone for a coming strong earthquake. The area with the simultaneous higher surface strain, principal compressive strain, shear strain and tendency accumulation might be the place with higher risk of strong earthquakes. Generally, the area with low strain and predominant tensile strain might have a small possibility for strong earthquake development, which belongs to a stable area. The evolution of horizontal strain obtained from GPS measurements carried out in Baotou-Datong area in the period of 1992–1999 reflects the total developing and ending processes of the seismic episode from 1996 to 1998. The area with high and predominant compressive strain and the strain gradient zone can be considered as one of the indicators for determining the strong earthquake risk area in the future.     

鄂尔多斯地块周围的现代地壳应力场

根据近十年来区域台网的P波初动方向观测资料,得到了鄂尔多斯地块周围13个分区的综合地震节面解;结合已有的结果进行分析,地块周围确实存在有别于华北地区地壳应力场基本情况的小区域应力场:地块西南边缘的六盘山褶皱带处于北东东向的水平挤压应力状态;地块边缘的断陷盆地处于北西向的水平拉张应力状态,尤其是渭河盆地到临汾盆地的主压应力轴已近于直立;地块西北角和东北角处于北西向的水平拉张与北东向的水平挤压共同作用的应力状态;在地块的西面与北面,从北到南和由西往东,主压应力轴的走向由北北东向逐渐转变为近东西向。 此外,还对本文结果在板内动力学中的意义进行了简要的讨论。     

Active blocks and their deformations derived from the velocity field in North China

Based on the horizontal movement velocities and their error estimations of 144GPS stations in North China de-duced from the results obtained from multiple GPS measurements carried out in the period of 1992-2001,the horizontal deformation in the area is stuklied.The movements,entire deformations,local deformations,activeity patterns and intensities along the boundary zones are derived.And then the risk of strong earthquake in the area is estimated.In the research,the horizontal displacement observations can be considered as the sum of three parts.The first part is the entire motion following Eurasian plate,which can be derived from NUVAL-IA model;the second part is the relative motions and deformations between the sub-tectonic blocks in the studied area,which can be derived from a set of displacement observations determined by the expanded QUAD method in the paper;the third part is the local deformations and errors in the sub-tectonic blocks,which can be described as the inhomoge-neous strains of the block.The method and results are introduced in detail in the paper.     

块体系统非连续变形数值方法──DDA及其在地壳应力分析中的应用

介绍了块体系统非连续变形分析数值方法的基本理论及特点,讨论了DDA解算大地测量资料应解决的问题根据地质构造背景建立大华北块体网络系统,利用华北GPS网3期观测资料进行地壳应力场反演,结果与原地应力测量资料和传统网平差最小二乘配置法吻合,表明DDA具备实际应用前景。最后对研究方向做了探讨。     

Spatial distribution and focal mechanism solutions of the Wenchuan earthquake series: Results and implications

We relocate the spatial distribution of the devastating 12 May 2008 Wenchuan earthquake and its aftershocks. The relocation database is obtained from 89 stations deployed by the China Earthquake Administration, including 54 525 seismograms from 1 376 local earthquakes over M_S 3.5 between 12 May 2008 and 3 August 2008. The cross-correlation technique used in this paper has greatly improved the relocation precision by giving much more accurate P-wave differential travel-time measurements than those obtained from routinely picked phase onsets. At the same time, we pick P-wave polarity observations of the Wenchuan earthquake series (hereafter referred to as WES) from 1 023 stations in China and 59 IRIS (incorporated Research Institutions of Seismology) stations. Then, employing a newly developed program CHNYTX, we obtain 83 well-determined focal mechanism solutions (hereafter referred to as FMSs). Based on spatial distribution and FMSs of the WES, we draw following conclusions: (1) The region near the main shock exhibits a buried low-angle northwest-dipping seismic zone with the main shock at its upper end and two conjugated seismic zones dipping southeast with roughly equal dip-angle; (2) The compressional directions of all kinds of FMSs of the WES are subhorizontal, which reflects the dominant stress in this area is compressional; (3) The principal compressional direction of the regional stress around Wenchuan is roughly perpendicular to the strike of Beichuan-Yingxiu fault, while around Qingchuan it is roughly parallel to the strike of Qingchuan fault. In intermediate part of the Longmenshan area, the principal compressional direction of the stress should be in-between; (4) The possibly existed molten materials in the lower crust of Songpan-Garze terrain have small contribution to the local stress state in Longmenshan area. The listric geometries of the Longmenshan faults most probably resulted from subhorizontal compression along NW-SE direction in history.