基于GNSS的青藏高原东北缘地壳运动场及强震趋势研究

利用“中国大陆构造环境监测网络”GNSS数据研究1998—2018年青藏高原东北缘排除同震影响等干扰后的速度场、主应变率场、最大剪切应变率场、面应变场等的变化,活动断裂滑动速率变化、跨活动断裂基线变化等。将研究区域内的二级块体再分区,获得各次级块体内部的应变率变化;获取研究区域地壳运动场的趋势性、动态特征。研究结果显示,阿尔金断裂带中东段、祁连块体和柴达木块体交界、巴颜喀拉块体与羌塘块体交界、祁连块体南边界中段、海原—六盘山断裂带和西秦岭北缘断裂带西段的逆冲运动,祁连块体北边界西段、庄浪河断裂的左旋走滑运动,祁连块体北边界东段、西秦岭北缘断裂带东段的左旋逆走滑运动,都属于造成一定程度地壳变形的持续性局部应变增强活动。阿尔金断裂带东段、东昆仑断裂带中西段、祁连块体北边界、庄浪河断裂北段、海原断裂南段、六盘山断裂北段、西秦岭北缘断裂带东段可能存在闭锁,未来十年可能发生M_S6.0以上地震。     

GPS观测及断裂晚第四纪滑动速率所反映的青藏高原北部变形

断裂晚第四纪滑动速率及现今GPS观测揭示了青藏高原向北扩展与高原边缘隆升的运动特征.主要断裂晚第四纪滑动速率及跨断裂GPS应变速率的结果表明,青藏高原北部边缘的断裂以低滑动速率（＜10 mm/a）为主,特别是两条边界断裂：阿尔金断裂和海原—祁连山断裂.两条主要边界断裂上的滑动速率分布显示了断裂间滑动速率转换及调整特征.阿尔金断裂自95°E以西的8～12 mm/a稳定滑动速率,向东逐渐降低到最东端的约1～2 mm/a,而海原断裂自哈拉湖一带开始发育后滑动速率为1～2 mm/a,到祁连一带（101°E以东）增大到相对稳定的4～5 mm/a,直到过海原后转向六盘山一带,滑动速率降低到1～3 mm/a,甚至更低.滑动速率的变化及分布特征显示,阿尔金断裂滑动主要是通过祁连山内部隆起及两侧新生代盆地变形引起的缩短来吸收的,海原—祁连山断裂的低滑动速率及沿断裂运动学特征表明断裂尾端的陇西盆地变形及六盘山的隆起是断裂左旋走滑速率的主要吸收方式.这一变形特征表明,青藏高原北部边缘的变形模式是一种分布式的连续变形,变形发生自高原内部,边界断裂的走滑被高原内部变形所吸收.     

日月山断裂德州段晚更新世以来的活动速率研究

日月山断裂位于柴达木-祁连活动块体内部,受到东昆仑断裂和祁连-海原断裂等主边界断裂控制,形成了块体内部夹持于主边界断裂之间的次级构造。该断裂的构造位置特殊,确定其晚更新世以来的活动速率可提供青藏高原东北缘向外扩展的最新活动信息。文中通过建立地貌面时间标尺,分析断错的地貌标志,获得了以下2点认识:1)晚更新世以来,日月山断裂德州段主要发育一级洪积扇面fp,三级河流阶地面T1、T2和T3。其中洪积扇fp的废弃年龄约(21.2±0.6)ka,河流阶地T2的废弃年龄约(12.4±0.11)ka;2)日月山断裂晚更新世晚期以来的右旋走滑速率约(2.41±0.25)mm/a,全新世以来的右旋走滑速率约(2.18±0.40)mm/a,垂直滑动速率约(0.24±0.16)mm/a。日月山断裂德州段的右旋走滑速率在晚更新世晚期以来基本不变。日月山断裂并未切错大型块体的边界,而是青藏高原东北缘地区夹持于区域大型左旋走滑断裂内部的1套右旋走滑断裂中的1支。在青藏高原东北缘整体生长和扩展的过程中,右旋走滑断裂对各次级块体之间的变形协调起着十分重要的调节作用。     

利用GPS数据反演阿尔金断裂现今滑动速率

利用2009—2013年的GPS水平速度场,使用三维线性球面弹性块体模型,综合前人研究成果建立了阿尔金断裂及其邻区的三维块体几何模型,反演得到阿尔金断裂不同断层段和其邻区主要活动断裂的现今滑动速率。结果表明:阿尔金断裂柴达木盆地以南段左旋走滑速率为(7.8±0.2)mm/a,该段向北至肃北左旋走滑速率为(7.5±0.1)mm/a,肃北—昌马段左旋走滑速率为5.3~5.5mm/a,昌马以北段的左旋走滑速率仅有(1.0±0.4)mm/a。阿尔金断裂左旋走滑速率总体表现出从南向北减小的趋势,衰减主要集中在祁连山地区,并转换为这一地区明显的地壳挤压作用。     

东昆仑断裂滑动速率变化及其对2017年九寨沟地震的应力加载

为了解东昆仑断裂活动对2017年8月8日九寨沟M_S7.0地震的影响,本文选取1999—2007年、2013—2017年GPS速度场作为约束,基于块体-位错模型反演计算东昆仑断裂两个时间段的块体运动速率、断裂滑动速率和滑动亏损率,并进一步研究青藏高原东缘最大剪应变率场和九寨沟震区的震间库仑应力累积速率.结果显示,东昆仑断裂中西段左旋走滑速率较高,东段走滑速率较低,自西向东逐步递减,存在明显的梯度.在两个时间段,阿坝块体刚性运动的方向顺时针偏转0.2°,运动速率由12.22mm·a^-1增大到15.96mm·a^-1;东昆仑断裂左旋走滑速率升高,其中西段较为明显(升高约1.2±0.3mm·a^-1);东昆仑断裂东段闭锁深度和闭锁程度增加;2013—2017年,东昆仑断裂滑动引起的九寨沟震区库仑应力累积速率是1999—2007年的3倍,最大剪应变率也明显升高.因此本文认为:2008年汶川地震和2013年芦山地震后,龙门山断裂部分解锁,阿坝地块活动性增强,东昆仑断裂滑动速率增大,导致九寨沟震区库仑应力加载速率增加,加速了九寨沟地震的孕育过程.     

基于GPS数据的海原-六盘山断裂带滑动速率亏损时空分布

利用青藏高原东北缘及周缘地区1999—2007年和2009—2014年2个时段的GPS水平运动速度场做约束,反演获取了海原-六盘山断裂带的闭锁程度和滑动速率亏损的时空分布演化。结果表明,海原断裂带以左旋走滑亏损为主,六盘山断裂北段以逆冲倾滑速率亏损为主,南段则以正向倾滑为主。其中,毛毛山断裂和老虎断裂西段在2个时段的闭锁深度都达到25km,最大左旋滑动亏损为6mm/a。老虎山东段和海原断裂(狭义)闭锁程度低,主要处于蠕滑状态。六盘山断裂2个时段的闭锁深度可达35km,最大逆冲滑动速率亏损为2mm/a。汶川地震后,六盘山断裂上逆冲滑动速率亏损高值区由中段迁移至北段且范围减小,南段则变成正倾滑速率亏损。毛毛山、老虎山西段和六盘山断裂的地震危险性要明显高于海原-六盘山断裂带其他断层段。     

1999～2001年青藏块体东北缘地壳水平运动的非震反位错模型及变形分析

通过对GPS观测资料的数值模拟，获取1999～2001年青藏块体东北缘地区地壳水平运动的非震反位错模型,结合本区视应变场空间分布，研究活动块体及其边界断裂运动、变形特征及应力应变积累部位和强度．结果表明:① 9个活动块体呈现东向由偏北至偏南的整体性顺时针运动. 以祁连山——海原断裂为界，两侧块体间的左旋相对运动明显，由西向东呈现走滑兼NE-NEE向挤压；② 有20条断层段（多数呈压性）不同程度地阻碍块体间的相对运动，其中祁连山断裂中东段（包括与日月山——拉脊山断裂交汇区）及与海原、庄浪河断裂交汇区更有利于应变积累，日月山——拉脊山断裂与柴达木块体北边界交汇区也可能存在一定程度的应变积累；③ 所得活动块体运动速率及边界断裂对块体相对运动的锁定量较1993～1999年相应结果有所减弱．      

青藏高原东北缘冷龙岭断裂全新世左旋滑动速率

冷龙岭断裂是青藏高原东北缘1条重要的左旋走滑断裂,断裂滑动速率对于青藏高原东北缘构造形变的动力学研究以及认识断裂的活动习性和地震危险性具有重要意义。但是,冷龙岭断裂的滑动速率仍然存在较大争议,被限定在3~24mm/a一个较为宽泛的范围内。文中以青海省门源县他里花沟上游走滑断裂断错地貌现象较为典型的牛头沟地区(37.440 2°N,102.094 0°E)和柴陇地区(37.447 3°N,102.063 0°E)作为研究对象,采用地基LiDAR获取的高分辨率DEM和高精度Google Earth卫星影像对断错地貌进行了位错演化模式分析和位错量的恢复测量,结合地貌面上开挖地层探坑和剥离新鲜地层剖面上的年代样品采集与测试,确定了断错地貌面的废弃年代。在牛头沟地区和柴陇地区得到的滑动速率分别为(6.4±0.7)mm/a和(6.6±0.3)mm/a,2个研究地区获得的结果存在较好的一致性。考虑到滑动速率的误差范围,认为冷龙岭断裂全新世以来的左旋滑动速率为(6.4±0.7)mm/a,该滑动速率介于前人采用地质方法获得的结果中间,也在In SAR得到的滑动速率4.2~8mm/a范围内,但比GPS速率((4.0±1.0)mm/a)稍大。祁连-海原断裂带弧形分布的晚第四纪滑动速率在冷龙岭地区达到最大,青藏高原东北缘在该地区最强烈的隆升也从1个侧面证实了冷龙岭断裂在调节青藏高原相对于戈壁-阿拉善地块向E运动方面所处的重要地位。     

GPS约束下九寨沟地区断裂带现今运动速率的非连续接触模拟研究

以中国地壳运动观测网络2009—2013年GPS观测数据为边界条件,使用非连续接触有限元技术构建九寨沟地区二维有限元模型,在不确定性分析的基础之上,计算区内主要断裂带现今运动速率。研究结果表明:在巴颜喀拉块体整体近于NE向的推挤过程中,九寨沟地区的塔藏断裂、虎牙断裂、树正断裂均呈现为较高的左旋走滑兼具挤压的现今运动特征;岷江断裂、龙日坝断裂和龙门山断裂则呈现为右旋走滑兼有挤压的运动特性。结合区域主应变率计算结果,发现九寨沟地区仍然具有较高的应变积累背景。树正断裂作为2017年8月8日九寨沟M7.0地震的发震断层,其现今左旋滑动速率为3.0 mm/a,与东昆仑断裂带玛沁—玛曲段附近的左旋走滑速率4.1mm/a基本匹配,说明该断裂可能是东昆仑断裂带东端分支断裂之一,而东昆仑断裂与虎牙断裂之间的历史地震空区可能已被九寨沟地震事件贯通。     

2008年于田7.3级地震前西昆仑地形变的GPS初步研究

利用GPS观测资料计算并获取了2008年新疆西昆仑地区于田7.3级地震发生前的现今地壳运动速度场,通过速度场分布研究了区域内主要断层的活动速率.结果表明:震中以南的龙木错断裂呈左旋走滑性质的运动特征,走滑速率为1.2～2.5 mm/a;震中以北的阿尔金左旋走滑断裂滑动速率为5 mm/a;震中北西面的康西瓦断裂的左旋走滑平均速率约为3～7 mm/a.区域应变场分布一定程度上受断裂带分布的影响.7.3级地震就位于断裂活动交汇的部位和最大剪应变率高值区的边缘.     

ANALYSIS OF EVOLUTION OF THE RIYUESHAN FAULT SINCE LATE PLEISTOCENE USING STRUCTURAL GEOMORPHOLOGY

The northeastern margin of Tibetan plateau is an active block controlled by the eastern Kunlun fault zone, the Qilian Shan-Haiyuan fault zone, and the Altyn Tagh fault zone. It is the frontier and the sensitive area of neotectonic activity since the Cenozoic. There are widespread folds, thrust faults and stike-slip faults in the northeastern Tibetan plateau produced by the intensive tectonic deformation, indicating that this area is suffering the crustal shortening, left-lateral shear and vertical uplift. The Riyueshan Fault is one of the major faults in the dextral strike-slip faults systems, which lies between the two major large-scale left-lateral strike-slip faults, the Qilian-Haiyuan Fault and the eastern Kunlun Fault. In the process of growing and expanding of the entire Tibetan plateau, the dextral strike-slip faults play an important role in regulating the deformation and transformation between the secondary blocks. In the early Quaternary, because of the northeastward expansion of the northeastern Tibetan plateau, tectonic deformations such as NE-direction extrusion shortening, clockwise rotation, and SEE-direction extrusion occurred in the northeastern margin of the Tibetan plateau, which lead to the left-lateral slip movement of the NWW-trending major regional boundary faults. As the result, the NNW-trending faults which lie between these NWW direction faults are developed. The main geomorphic units developed within the research area are controlled by the Riyueshan Fault, formed due to the northeastward motion of the Tibet block. These geomorphic units could be classified as:Qinghai Lake Basin, Haiyan Basin, Datonghe Basin, Dezhou Basin, and the mountains developed between the basins such as the Datongshan and the Riyueshan. Paleo basins, alluvial fans, multiple levels of terraces are developed at mountain fronts. The climate variation caused the formation of the geomorphic units during the expansion period of the lakes within the northeastern Tibetan plateau. There are two levels of alluvial fans and three levels of fluvial terrace developed in the study area, the sediments of the alluvial fans and fluvial terraces formed by different sources are developed in the same period. The Riyueshan Fault connects with the NNW-trending left-lateral strike-slip north marginal Tuoleshan fault in the north, and obliquely connects with the Lajishan thrust fault in the south. The fault extends for about 180km from north to south, passing through Datonghe, Reshui coal mine, Chaka River, Tuole, Ketu and Xicha, and connecting with the Lajishan thrusts near the Kesuer Basin. The Riyueshan Fault consists of five discontinuous right-step en-echelon sub-fault segments, with a spacing of 2~3km, and pull-apart basins are formed in the stepovers. The Riyueshan Fault is a secondary fault located in the Qaidam-Qilian active block which is controlled by the major boundary faults, such as the East Kunlun Fault and the Qilian-Haiyuan Fault. Its activity characteristics provide information of the outward expansion of the northeastern margin of Tibet. Tectonic landforms are developed along the Riyueshan Fault. Focusing on the distinct geomorphic deformation since late Pleistocene, the paper obtains the vertical displacement along the fault strike by RTK measurement method. Based on the fault growth-linkage theory, the evolution of the Riyueshan Fault and the related kinetic background are discussed. The following three conclusions are obtained:1)According to the characteristics of development of the three-stage 200km-long steep fault scarp developed in the landforms of the late Pleistocene alluvial fans and terraces, the Riyueshan Fault is divided into five segments, with the most important segment located in the third stepover(CD-3); 2)The three-stage displacement distribution pattern of the Riyueshan Fault reveals that the fault was formed by the growths and connections of multiple secondary faults and is in the second stage of fault growth and connection. With CD-3 as the boundary, the faults on the NW side continue to grow and connect; the fault activity time on the SE side is shorter, and the activity intensity is weaker; 3)The extreme value of the fault displacement distribution curve indicates the location of strain concentration and stress accumulation. With the stepover CD-3 as the boundary, the stress and strain on NW side are mainly concentrated in the middle and fault stepovers. The long-term accumulation range of stress on the SE side is relatively dispersed. The stress state may be related to the counterclockwise rotation inside the block under the compression of regional tectonic stress.     

天山地震带境内外主要断层滑动速率和地震矩亏损分布特征研究

本文搜集、整理1998—2013年境内外天山及周边地区(包括中国新疆、哈萨克斯坦、吉尔吉斯斯坦等)500余个GPS观测点数据,采用GAMIT/GLOBK软件对其进行解算和平差计算,并利用了弹性块体模型计算区域块体边界断层闭锁深度、块体运动参数和主要活动断层的滑动速率.研究结果表明,东、西昆仑地震带闭锁深度最大(19km),其次为南天山地区,闭锁深度达到17km,闭锁深度最小的为哈萨克斯坦(13km);各块体相对欧亚板块作顺(逆)时针旋转,旋转速率最大(-0.7208±0.0034°/Ma)为塔里木块体,其围绕欧拉极(38.295±0.019°N,95.078±0.077°E)顺时针方向转动,旋转速率最小为天山东段(0.108±0.1210°/Ma),而天山东、西两段无论是在旋转速率上还是在旋转方向上都有显著的区别.西昆仑断裂带的滑动速率(10.2±2.8mm·a-1)最大,南天山西段滑动速率为9.5±1.8mm·a-1,其东段为3.9±1.1mm·a-1;而北天山东段滑动速率(4.7±1.1mm·a-1)高于北天山西段(3.7±0.9mm·a-1);塔里木盆地南缘的阿尔金断裂带平均滑动速率为7.6±1.4mm·a-1,其结果与阿勒泰断裂带滑动速率(7.6±1.6mm·a-1)基本相当;天山断裂带运动方式主要以挤压为主,而阿尔金、昆仑、阿尔泰以及哈萨克斯坦断裂带均是以走滑运动方式为主,除阿勒泰断裂带走滑方式为右旋以外,其余几个断裂带均为左旋运动.最后,利用主要断裂带的滑动速率计算出各地震带的地震矩变化率以及1900年以来地震矩累计变化量,其结果与利用地震目录计算所得到的地震矩进行比较,判定出各地震带上地震矩均衡分布状态,研究结果显示阿尔金、西昆仑、东昆仑和北天山东段断裂带存在较大的地震矩亏损,均具有发生7级以上地震的可能性,南天山东段和哈萨克斯坦断裂带地震矩亏损相对较小,具有孕育6~7级地震的潜能,而天山西段、阿勒泰地震矩呈现出盈余状态,不具在1~3年内有发生强震的可能.     

SLIP RATES OF THE RIYUE MT. FAULT AT DEZHOU SEGMENT SINCE LATE PLEISTOCENE

The Riyue Mt. Fault is a secondary fault controlled by the major regional boundary faults (East Kunlun Fault and Qilian-Haiyuan Fault). It lies in the interior of Qaidam-Qilianshan block and between the major regional boundary faults. The Riyue Mt. fault zone locates in the special tectonic setting which can provide some evidences for recent activity of outward extension of NE Tibetan plateau, so it is of significance to determine the activity of Riyue Mt. Fault since late Pleistocene to Holocene. In this paper, we have obtained some findings along the Dezhou segment of Riyue Mt. Fault by interpreting the piedmont alluvial fans, measuring fault scarps, and excavating trenches across the fault scarp. The findings are as follows:(1) Since the late Pleistocene, there are an alluvial fan f_p and three river terraces T₁-T₃ formed on the Dezhou segment. The abandonment age of f_p is approximately (21.2±0.6) ka, and that of the river terrace T₂ is (12.4±0.11) ka. (2) Since the late Pleistocene, the dextral strike-slip rate of the Riyue Mt. Fault is (2.41±0.25) mm/a. In the Holocene, the dextral strike-slip rate of the fault is (2.18±0.40) mm/a, and its vertical displacement rate is (0.24±0.16) mm/a. This result indicates that the dextral strike-slip rate of the Riyue Mt. Fault has not changed since the late Pleistocene. It is believed that, as one of the dextral strikeslip faults, sandwiched between the the regional big left-lateral strike-slip faults, the Riyue Mt. Fault didn't cut the boundary zone of the large block. What's more, the dextral strike-slip faults play an important role in the coordination of deformation between the sub-blocks during the long term growth and expansion of the northeast Tibetan plateau.     

NEW DISCOVERY OF RESHUI-TAOSTUO RIVER FAULT IN DULAN,QINGHAI PROVINCE AND ITS IMPLICATIONS

The 40km-long, NEE trending Reshui-Taostuo River Fault was found in the southern Dulan-Chaka highland by recent field investigation, which is a strike-slip fault with some normal component. DEM data was generated by small unmanned aerial vehicle(UAV)on key geomorphic units with resolution<0.05m. Based on the interpretation and field investigation, we get two conclusions:1)It is the first time to define the Reshui-Taostuo River Fault, and the fault is 40km long with a 6km-long surface rupture; 2)There are left-handed dislocations in the gullies and terraces cut by the fault. On the high-resolution DEM image obtained by UAV, the offsets are(9.3±0.5) m, (17.9±1.5) m, and(36.8±2) m, measured by topographic profile recovery of gullies. The recovery measurements of two terraces present that the horizontal offset of T₁/T₀ is(18.2±1.5) m and the T₂/T₁ is (35.8±2) m, which is consistent with the offsets from gullies. According to the historical earthquake records, a M5 3/4 earthquake on April 10, 1938 and a M_S5.0 earthquake on March 21, 1952 occurred at the eastern end of the surface rupture, which may be related to the activity of the fault. By checking the county records of Dulan and other relevant data, we find that there are no literature records about the two earthquakes, which is possibly due to the far distance to the epicenter at that time, the scarcity of population in Dulan, or that the earthquake occurred too long ago that led to losing its records. The southernmost ends of the Eastern Kunlun Fault and the Elashan Fault converge to form a wedge-shaped extruded fault block toward the northwest. The Dulan Basin, located at the end of the wedge-shaped fault block, is affected by regional NE and SW principal compressive stress and the shear stress of the two boundary faults. The Dulan Basin experienced a complex deformation process of compression accompanying with extension. In the process of extrusion, the specific form of extension is the strike-slip faults at each side of the wedge, and there is indeed a north-east and south-west compression between the two controlling wedge-shaped fault block boundary faults, the Eastern Kunlun and Elashan Faults. The inferred mechanism of triangular wedge extrusion deformation in this area is quite different from the pure rigid extrusion model. Therefore, Dulan Basin is a wedge-shaped block sandwiched between the two large-scale strike-slip faults. Due to the compression of the northeast and southwest directions of the region, the peripheral faults of the Dulan Basin form a series of southeast converging plume thrust faults on the northeast edge of the basin near the Elashan Fault, which are parallel to the Elashan Fault in morphology and may converge with the Elashan Fault in subsurface. The southern marginal fault of the Dulan Basin(Reshui-Taostuo River Fault)near the Eastern Kunlun fault zone is jointly affected by the left-lateral strike-slip Eastern Kunlun Fault and the right-lateral strike-slip Elashan Fault, presenting a left-lateral strike-slip characteristic. Meanwhile, the wedge-shaped fault block extrudes to the northwest, causing local extension at the southeast end, and the fault shows the extensional deformation. These faults absorb or transform the shear stress in the northeastern margin of the Tibet Plateau. Therefore, our discovery of the Dulan Reshui-Taostuo River Fault provides important constraints for better understanding of the internal deformation mode and mechanism of the fault block in the northeastern Tibetan plateau. The strike of Reshui-Taostuo River Fault is different from the southern marginal fault of the Qaidam Basin. The Qaidam south marginal burial fault is the boundary fault between the Qaidam Basin and the East Kunlun structural belt, with a total length of ~500km. The geophysical data show that Qaidam south marginal burial fault forms at the boundary between the positive gravity anomaly of the southern East Kunlun structural belt and the negative gravity anomaly gradient zone of the northern Qaidam Basin, showing as a thrust fault towards the basin. The western segment of the fault was active at late Pleistocene, and the eastern segment near Dulan County was active at early-middle Pleistocene. The Reshui-Taostuo River Fault is characterized by sinistral strike-slip with a normal component. The field evidence indicates that the latest active period of this fault was Holocene, with a total length of only 40km. Neither remote sensing image interpretation nor field investigation indicate the fault extends further westward and intersects with the Qaidam south marginal burial fault. Moreover, it shows that its strike is relatively consistent with the East Kunlun fault zone in spatial distribution and has a certain angle with the burial fault in the southern margin of Qaidam Basin. Therefore, there is no structural connection between the Reshui-Taostuo River Fault and the Qaidam south marginal burial fault.     

青藏高原北部大型走滑断裂带近地表地质变形带特征分析

阿尔金断裂带、东昆仑断裂带和海原断裂带是青藏高原北部的大型左旋走滑断裂带,具有相对高的地质和GPS滑动速率,地表破裂型地震频发。在阿尔金断裂带阿克塞老城西和半果巴、东昆仑断裂带西大滩和玛沁、海原断裂带松山等地点的探槽地质剖面揭露了这些走滑断裂带累积地质变形带的基本特征。阿尔金断裂带半果巴探槽和阿克塞老城西探槽、东昆仑断裂带西大滩探槽和玛沁探槽揭露出的地质变形带宽度约12m左右;海原断裂带松山拉分盆地边界单条走滑断层地质变形带宽度不足10m,考虑到地震期间拉分盆地可能会出现较严重的变形,则拉分盆地本身也应作为强变形带处理。由此可见,经历过多个地震地表破裂循环的东昆仑断裂带、海原断裂带和阿尔金断裂带其地质变形带的宽度是有限的,具有变形局部化特征。单条走滑断层的地质变形带宽度一般为10余米,比较保守地估计应<30m,走滑断层斜列阶区的地质变形带宽度取决于阶区本身的宽度     

巴颜喀拉块体东部活动块体的划分、形变特征及构造意义

基于活动块体的基本概念,综合对研究区内活动断裂带空间展布、地震活动性等资料的分析将巴颜喀拉块体东部及邻区划分为巴颜喀拉块体（I）、华南块体（Ⅱ）、川滇块体（Ⅲ）和西秦岭块体（IV）等4个一级块体.利用GPS形变场、地球物理场等资料结合F检验法,将巴颜喀拉块体划分为阿坝（I₁）、马尔康（I₂）和龙门山（I₃）3个次级块体,将西秦岭块体划分为岷县（IV₁）和礼县（IV₂） 2个次级块体.利用分布在各个块体内部的GPS测站,计算各活动块体及块体边界断裂带的运动变形特征.结果表明：各活动块体的整体运动包括平移和旋转运动;东昆仑断裂带、甘孜—玉树断裂带和鲜水河断裂带的滑动速率明显高于龙门山断裂带的滑动速率;巴颜喀拉块体东部走向北西或北西西的边界断裂表现出左旋拉张的特性;走向北东的边界断裂带,除成县—太白断裂带外,均表现出右旋走滑兼挤压的活动特征.巴颜喀拉块体的东向运动存在自西向东的速度衰减,衰减主要被龙日坝断裂带和岷江断裂带分解吸收,其中龙日坝断裂带的水平右旋分解非常明显,约为~4.8±1.6 mm/a,岷江断裂带的水平分解较弱.龙门山断裂带被马尔康、龙门山和岷县等次级块体分成南、中、北三段,龙门山断裂带中段上的主压应变率要明显小于龙门山断裂带南段上的应变率,其北西侧变形幅度从远离断裂带较大到靠近断裂带逐渐减小,表明其在震前已经积累了较高的应变能,有利于发生破裂滑动.汶川地震后,地表破裂带和余震分布揭示的断裂带运动性质自南西向北东由以逆冲运动为主,逐渐转为逆冲兼走滑的特征可能与龙门山断裂带中段所受主压应力方向自南西向北东的变化有关.马尔康、龙门山和岷县3个次级块体与华南块体之间较低的相对运动速度以及龙门山断裂带低应变率、强闭锁的特征都决定了汶川地震前龙门山断裂带低滑动速率的运动特征.     

东昆仑断裂带东段玛曲断裂新活动特征及全新世滑动速率研究

东昆仑活动断裂是青藏高原东北部一条重要的NWW向边界断裂。 玛曲断裂位于东昆仑断裂带的最东段。 根据野外考察结果认为玛曲断裂全新世以来活动强烈, 主要表现为左旋走滑运动, 并伴有正倾滑运动性质。 断错地貌特征明显, 断裂过玛曲县城以后, 沿黑河南岸穿过若尔盖草地向东, 直至岷山北端求吉附近。 通过两处断错地貌的全站仪器实测和测年资料讨论了玛曲断裂新活动特征和全新世滑动速率, 玛曲断裂全新世早期以来的平均水平滑动速率为6.29～5.71 mm/a, 全新世晚期以来的平均水平滑动速率为4.19～4.03 mm/a。     

青海拉脊山断裂带新活动特征的初步研究

拉脊山断裂带由拉脊山北缘断裂和拉脊山南缘断裂两条向NE凸出的弧形断裂所组成，分别长约230km和220km。它们是介于NNW向的热水一日月山右旋走滑断裂带和NWW向的西秦岭北缘左旋走滑断裂带之间的一个大型挤压构造区和构造转换带，也是分隔拉脊山南北两侧的西宁一民和盆地和循化一化隆盆地的重要边界断裂。沿断裂带的追踪考察，发现了其新活动的部分地质地貌证据。其最新活动时代为晚更新世晚期(仅局部为全新世早期)，性质以挤压逆冲为主稍具左旋特征。该断裂的新活动可能导致了该区20余次5级左右中等地震的发生。可以说，拉脊山地区既是反映构造活动，又是反映地震活动的地震构造窗。     

滇西南地区孟连断裂晚第四纪走滑速率的厘定

通过卫星影像解译和野外实地调查,获得滇西南地区孟连断裂的几何特征和活动性参数。孟连断裂总体走向NE-NEE向,不具有明显的分段性,连续性较好。断裂从单侧控制着沿线的勐滨、孟连和勐马三个新生代盆地的发育。断裂沿线地貌以线性较好的断层谷、断层崖和断层陡坎为主,并发育多级左旋位错的河流、冲沟和阶（台）地等,观测到的最小左旋位错约为7 m。采用高精度Li-DAR测量方法,对4处典型水平位错地貌进行精细测量,根据获得的相应地貌面年代,得到孟连断裂晚第四纪以来平均左旋走滑速率为2.2±0.4 mm/a。其结果与滇西南地区其他NE向左旋走滑断裂滑动速率相当,反映了区域构造活动的整体协调性。根据跨断层地质体最大左旋位错量9.5±1.8 km,估算断裂开始左旋走滑的时代为距今4.7±1.6 Ma左右,即中新世中晚期。