Joints as fingerprints of stress in the quaternary carbonate deposits along coastal Saurashtra,Western India

Coastal cliffs and shore platforms are important geomorphic features of coastal areas of Saurashtra. These features are composed of medium to coarse grained carbonate sand and are designated as “Miliolitic limestones” that range in age from Middle to Late Pleistocene. Significant jointing has been observed in the Middle Pleistocene Miliolite Formation as well as in the younger shell limestone that comprises Chaya Formation of Late Pleistocene. Along with NE-SW trend which is the direction of maximum horizontal compressive stress [S_Hmax] for Indian sub-continent, other trends recorded are NNE-SSW, N-S, NW-SE and E-W. When compared with other regional studies, neotectonic episode in Saurashtra peninsula appears to be younger than at least 125ky. The present study on joint sets also indicates that they are important to understand stresses associated with anticlockwise rotation of the Indian plate.     

Landslides and neotectonic activities in the Main Boundary Thrust (MBT) zone: Southeastern Kumaun,Uttarakhand

Main Boundary Thrust (MBT) zone is constituted of some of the landslide prone areas in southeastern part of Kumaun Sub-Himalaya. Role of landslides as natural hazard and hill slope modifying agent is well documented from various part of Himalayan region and southern hills of Kumaun particularly in the MBT zone, which are susceptible to various type of mass movement. The rocks making up the slopes has been put to a number of brittle deformation phases during the movement along the MBT, and are traversed by number of joint sets. In the open slope these intersecting joint sets forms wedges and are the most favorable site for initiation of rockfalls and other types of landslides. Landslides are taking place primarily due to high angle slopes, formation of structural wedges along the free steep slopes, sheared nature of the rocks due to proximity to the MBT and neotectonic activities along the MBT and other transverse faults. Wedge failure is a common type of landslides in rock slopes characterized by multiple joints and acts as sliding planes for the failed blocks. Field observations and wedge failure analysis indicates most of the landslides taking place in MBT zone of Kumaun Sub-Himalaya are joint controlled. Safety Factor analysis suggests MBT zone of Kumaun Sub-Himalayan region is prone to landslides and related mass movements. This zone is also neotectonically active as indicated by various geomorphic signatures such as structurally controlled drainage pattern, offsetting of fan by MBT and formation of number of small lakes.     

新构造学研究趋势的展望

本文在简述新构造学发展过程的基础上，提出并论述了新构造学今后研究的七个领域：（１）全球变化；（２）现代大陆动力学；（３）新构造运动序列和新构造变形体系的建立；（４）青藏高原和沿海地区新构造；（５）活动构造；（６）现代构造运动；（７）新构造与地震及自然灾害、资源开发和环境的关系。     

基于构造地貌参数的新构造运动研究进展与思考

构造地貌是新构造运动与外地质营力以岩石为物质基础相互作用的产物,是反映新构造运动最为直观的信息载体。构造地貌参数是对内力作用形成地貌的外在形态特征的定量化表达,对于定量化揭示新构造运动信息具有较大的潜力。基于地貌过程对构造抬升的敏感响应,河流和山坡地貌形态特征成为记录新构造运动信息理想载体。分析了具有显著影响的基于河流水力侵蚀模型的河流地貌参数的应用原理,介绍了Martin D.Hurst等2013年在山坡地貌参数对构造隆升延缓响应方面的最新研究成果,并尝试讨论了这些地貌参数对构造抬升的指示意义。认为构造地貌参数能够较好地揭示隐含在构造地貌形态中的新构造运动信息;获取不同时段的地貌参数可以实现对现代构造地貌过程的动态研究,以获取最新的地壳活动信息。但是,构造地貌研究并不能解决构造活动的年代序列问题,同时也难以排除一些非构造因素的影响,目前构造地貌参数在新构造运动中的应用仍处于定性研究的瓶颈阶段。结合构造地貌参数和地质、地貌记录以及实验模拟,建立地貌参数的混合模型是实现利用地貌参数进行新构造运动定量化研究的重要途径。     

Late quaternary deformation and palaeoseismicity: Insight into geomorphotectonic evolution of Kachchh, western Indian Subcontinent

Kachchh in western Indian Shield, according to the Bureau of Indian Standard (IS:1893:2002), falls in Seismic Zone V. This is intriguing considering that the region is far away from active Plate margin. Apart from the recent incidences of earthquakes, there are several pre-historic/archaeological records of earthquakes in the region. Beyond these, the geological evidence of earth-movements (causing earthquakes) is provided by the occurrence of several’ active’ faults, which are considered geological markers of palaeoseismicity. There are records of innumerable incidences of faulting in the region in not so distant geological past. Study of fault features especially the scarp faces marking abrupt change in physical relief proves that the different levels of topography in the entire terrain are fault-bound features. Studies also confirm that the topographic difference between the high and ’sunken’ features have formed due to uplift and relative down-sagging during the geomorphotectonic evolution of the terrain. Features that make the region unique are: (i) restriction of fault-related deformation zone to a narrow strip between the southern margin of Thar Desert and the south coast line of the Kachchh Peninsula; (ii) overall sub-horizontality of bedding and other topographic and planation surfaces over the entire region; (iii) evidence of fault-controlled geomorphology indicating vertical movement along fault planes; (iv) evidence constraining the time of geomorphological evolution of the terrain only during the Late Quaternary, making it the youngest neotectonically evolved terrain in the Precambrian Indian Shield.     

Drainage patterns in southeast Queensland: the key to concealed geological structures?

Southeast Queensland's geomorphology is characterised by northwest – southeast-trending trunk drainage channels and highlands that strongly correlate with the distribution of geological units and major faults. Other geomorphological trends strongly coincide with subsidiary faults and geological domains. Australia is presently under compressional stress. Seismicity over the past 130 years records 56 earthquakes of >2 magnitude indicating continuing small-scale earth movements in the Moreton region. Highlands in this region are dominated by Paleozoic to Triassic metamorphic and igneous rocks, and are generally 20 – 80 km from the coastline. Coastal lowlands are largely dominated by Mesozoic sedimentary basins and a veneer of surficial sediments. The eastern coast of Australia represents a passive margin; crustal sag along this margin could be expected to produce relatively short, high-energy, eastward-flowing drainage systems. We performed a geomorphological analysis to characterise the drainage patterns in southeast Queensland and identify associations with geological features. Anomalous channel, valley and escarpment features were identified, which failed to match the anticipated drainage model and also lacked obvious geological control. Despite their proximity to the coast (base level), these features include areas where drainage channels flow consistently away from, or parallel to, the coastline. Although many channels do coincide with geological structures, the drainage anomalies cannot be directly related to known structural discontinuities. Anomalous drainage patterns are suggested to indicate previously unidentified structural features and in some cases relatively young tectonic control on the landscape. Recent seismicity data have also been analysed to assess spatial correlations between earthquakes and geomorphological features. Our results show that structure largely controls drainage patterns in this region, and we suggest that a presently unmapped and potentially active, deep-seated structure may exist parallel to the coast in the northern coastal region. We propose that this structure has been associated with uplift in the coastal region of southeast Queensland since mid-Cenozoic times.     

青藏高原西缘班公错地区新构造运动特征

青藏高原西缘的班公错地区是青藏高原西构造结的典型区域,更是研究青藏高原中更新世以来构造活动、地貌演化和环境演变的重要区域。依据野外调查结果,借助卫星遥感影像的解译和数字高程模型地形地貌特征的分析,对该地区的新构造运动特征以及其与地形地貌特征的耦合进行了研究。研究结果显示,研究区地貌分区特征以中大起伏山地（地势起伏度500~2 500 m）地貌为主,平原、台地少有发育;班公错地区断层走向分为近EW向、NW向、NE向和NNE向4组,其中近EW向为主体,断陷盆地多具有拉分断陷特征;区内晚新生代地层发育,尤其第四纪冲洪积物和湖积物广泛展布,并受断层的控制具有线性发育特征,湖积阶地和冲洪积阶地发育,班公错北岸乌奖附近拔湖高度62 m、65 m、98 m的沉积阶地钙质堆积物年龄为（23.8±2.3)、（33.9±4.0)、（78.0±8.0)万年;区内地震频发,1970年以来的40年间,4级以上地震达到303次,其中6级以上强震达到7次。众多地质事实指示该地区的中更新世以来为较强烈的、阶段性快速构造抬升和剧烈的剥蚀作用、动荡的构造环境。     

Geomorphic characteristics of a bedrock river inferred from drainage quantification,longitudinal profile,knickzone identification and concavity analysis: a DEM-based study

An examination of river channels has ability to provide substantial information regarding the geomorphic characteristics, control of lithology, tectonic uplift and geomorphic evolution during the geological past of an area. In this paper, a detailed study of geomorphic and structural investigation has been carried out for Pravara basin, Maharashtra, with the help of 90-m resolution SRTM DEM and geospatial techniques. Drainage network analysis performed in this paper demonstrates the general geomorphic characteristics, while the analysis of longitudinal profile synthesises lithological control over Pravara basin. Pravara is a 6th order drainage basin, encompassing an area of 2637 km². Bifurcation ratio reveals low to moderate structural control. Due to the hard rock lithology, the drainage density and stream frequency are low, and it indicates higher permeability in the sub-surface layers. The shape parameters denote that Pravara is highly elongated and it is easier to control floods in this basin. Relief parameters show very steep slope and higher vulnerability to the slope failure in some areas. Upstream of Pravara river has shown that series of breaks and knickzones indicate active erosion and acute lithological control on the channel. Major breaks are observed only in the main channel whereas in two major tributaries, no such breaks found, instead these tributaries are characterised by several knickzones which indicate regional variation in the lithological physiognomies. Different lithological stages on knickpoint and channel incision substantiate rejuvenation of Pravara river in several phases during geological past. The geospatial methodology carried out in this study can be pragmatic elsewhere around this world to recognise the geomorphic appearances and lithological control of a drainage basin.     

Appraisal of relative tectonic activity along the Kazerun Fault Zone,Zagros Mountains,Iran: insight from spatial analysis of geomorphic indices

This paper investigates the impact of active tectonics on the geomorphic processes and landscape evolution along the Kazerun Fault Zone (KFZ) in the Zagros Mountains of Iran using spatial analysis of geomorphic indices. We document how topography and morphology are influenced by active tectonic deformation. The Zagros fold–thrust belt is an area of active crustal shortening where northwest–southeast oriented fault‐related folds become younger from north to south and from southeast to northwest. This temporal and spatial evolution of the belt was tested using geomorphic indices of active tectonics that include mountain front sinuosity index (Smf), the valley width/height ratio (Vf), drainage basin asymmetry factor, hypsometric integral, drainage basin shape ratio and mean axial slope of the channel. Change in the geomorphic indices is the result of active fold growth and change in the uplift rate. Decreasing Smf and Vf values from north (Smf = 2.01; Vf = 0.5) to south (Smf = 1.12; Vf = 0.2) and from southeast (Smf = 1.84; Vf = 0.8) to northwest (Smf = 1.54; Vf = 0.1) points to a migration of the active crustal shortening towards W–SW. The combined geomorphic (field evidences) and morphometric data (quantitative analysis of geomorphic indices) provide evidence of relative variation in the tectonic activity along the Kazerun Fault Zone and related landforms. The utilization of geomorphic parameters with comparison to the field observations exhibits change in relative tectonic activities mostly corresponding to the change in mechanism of the prominent fault zones in the study area. Copyright © 2014 John Wiley & Sons, Ltd.     

Neotectonic Control on the Geomorphic Evolution of the Gangotri Glacier Valley, Garhwal Himalaya

The paper records evidences of neotectonic activities in the Gangotri glacier valley that are found to be responsible for the present-day geomorphic set-up of the area since the last phase of major glaciation. Geomorphological features indicate the presence of a large glacier in the valley in the geological past. Prominent planar structures present in the rocks were later on modified into sets of normal faults in the present-day Himalayan tectonic set-up giving rise to graben structures. The block nearest the snout is traversed by the NW-SE trending Gaumukh fault. A number of terraces mark the entrenchment of Bhagirathi River in this part. The contrasting drainage morphometric parameters of two sides of the valley and asymmetric recessional patterns of the tributary glaciers further document movement along the fault. The distribution and orientation of debris fans also seem to be controlled by neotectonic activity. The neotectonic activity that followed the process of deglaciation has brought the glacially carved, wide U- shaped valley in contact with the present-day fluvially incised narrow and relatively deep valley. The wider segments have become sites of active deposition of glacially eroded debris. The low gradient and excessive filling has resulted in the river attaining a braided nature in these segments.     

Estimation of seismic hazard in Gujarat region, India

The seismic hazard in the Gujarat region has been evaluated. The scenario hazard maps showing the spatial distribution of various parameters like peak ground acceleration, characteristics site frequency and spectral acceleration for different periods have been presented. These parameters have been extracted from the simulated earthquake strong ground motions. The expected damage to buildings from future large earthquakes in Gujarat region has been estimated. It has been observed that the seismic hazard of Kachchh region is more in comparison with Saurashtra and mainland. All the cities of Kachchh can expect peak acceleration in excess of 500?cm/s² at surface in case of future large earthquakes from major faults in Kachchh region. The cities of Saurashtra can expect accelerations of less than 200?cm/s² at surface. The mainland Gujarat is having the lowest seismic hazard as compared with other two regions of Gujarat. The expected accelerations are less than 50?cm/s² at most of the places. The single- and double-story buildings in Kachchh region are at highest risk as they can expect large accelerations corresponding to natural periods of such small structures. Such structures are relatively safe in mainland region. The buildings of 3?C4 stories and tall structures that exist mostly in cities of Saurashtra and mainland can expect accelerations in excess of 100?cm/s² during a large earthquake in Kachchh region. It has been found that a total of 0.11 million buildings in Rajkot taluka of Saurashtra are vulnerable to total damage. In Kachchh region, 0.37 million buildings are vulnerable. Most vulnerable talukas are Bhuj, Anjar, Rapar, Bhachau, and Mandvi in Kachchh district and Rajkot, Junagadh, Jamnagar, Surendernagar and Porbandar in Saurashtra. In mainland region, buildings in Bharuch taluka are more vulnerable due to proximity to active Narmada-Son geo-fracture. The scenario hazard maps presented in this study for moderate as well as large earthquakes in the region may be used to augment the information available in the probabilistic seismic hazard maps of the region.     

Holocene tectono-geomorphic evolution of Haryana plains,Western Ganga plain,India

Haryana plain is the drainage divide between the Ganga plain in the east and the Indus plain in the west. Being a part of the Himalayan foreland, its geomorphology, sedimentation processes, and tectonism are broadly controlled by the Himalayan tectonics. Soil and geomorphological mapping in Haryana plain bring out geomorphic features such as paleochannels, various active drainage patterns, and landforms such as old fluvial plains, floodplains, piedmonts, pediments, terminal fans, and eolian plains. Based on the degree of soil development, and Optical stimulated luminescence (OSL) ages, the soil-geomorphic units were grouped into six members (QIMS-I to VI) (Quaternary Indus Morphostratigraphic Sequence) of a morphostratigraphic sequence: QIMS-VI 9.86–5.38 Ka, QIMS-V 5.38–4.45 Ka, QIMS-IV 4.45–3.60 Ka, QIMS-III 3.60–2.91 Ka, QIMS-II <?2.91–1.52 Ka, and QIMS-I <?1.52 Ka. OSL chronology of different geomorphic features suggests six episodes of tectono-geomorphic evolution in the region since 10 Ka. Neotectonic features such as nine faults, two lineaments, and five fault-bounded tectonic blocks have been identified. Independent tilting and sagging of the blocks in response to neotectonics have resulted in modification of landforms, depositional processes, and hydro-geomorphology of the region. Major rivers like the Yamuna, the Ghaggar, and the Sutlej show different episodes of shifting of their courses. Lineament controlled few extinct channels have been recorded between 20 and 25 m depth below the surface in the ground-penetrating radar (GPR) profiles. These buried channels are aligned along the paleo-course of the Lost Saraswati River interpreted from the existing literature and hence are considered as the course of the lost river. Seven terminal fans have been formed on the downthrown blocks of the associated faults. The Markanda Terminal Fan, the first of such features described, is indeed a splay terminal fan and was formed by a splay distributary system of the Markanda River. Association of three terminal fans of different ages with the Karnal fault indicates the segment-wise development of the fault from west to east. Also, comparison with other such studies in the Ganga plain to further east suggests that the terminal fans formed by streams with distributary drainage pattern occur only in semiarid regions as in the present area and thus are indicators of semiarid climate/paleoclimate. Though the whole region is tectonically active, the region between the Rohtak fault and Hisar fault is most active at present signified by the concentration of earthquake epicenters.     

Tectonic geomorphology of the Kemalpaşa Basin and surrounding horsts,southwestern part of the Gediz Graben,Western Anatolia

The Kemalpa?a Basin is one of the Quaternary basins in Western Anatolia and represents the south-western branch of the Gediz Graben system in this extensional province. This basin has been formed under the NNE–SSW trending extensional tectonic regime. It is bounded by a major fault, the Kemalpa?a Fault, in the south and it is bounded by a number of downstepping faults, called as Spilda?? Fault Zone, in the north. Both margin-bounding faults of the Kemalpa?a Basin are oblique-slip normal faults. In order to better understand the activities of these faults, we investigated the tectonic geomorphology of the Kemalpa?a Basin and interpreted the effect of tectonic activity on the geomorphological evolution using geomorphic markers such as drainage basin patterns, facet geometries and morphometric indices such as hypsometric curves and integral (HI), basin shape index (B_s), valley floor width-to-height ratio (V_f) and mountain front sinuosity (S_mf). The morphometric analysis of 30 drainage basins in total and mountain fronts bounding the basin from both sides suggests a relatively high degree of tectonic activity. The mountain front sinuosity (S_mf) generally varies from 1.1 to 1.3 in both sides of the basin suggesting the active fronts and facet slopes (12°–32°) suggest a relatively high degree of activity along the both sides of the Kemalpa?a Basin. Similarly, the valley floor width-to-height ratios (V_f) obtained from the both sides indicate low values varying from 0.043 to 0.92, which are typical values (<1) for tectonically active mountain fronts. The all values obtained are lower for the southern side. Therefore, we suggest that the tectonic activity of the Kemalpa?a Fault higher than the Spilda?? Fault Zone. This difference that can be arised from the different uplift rates also reveals the typical asymmetric characteristics of the Kemalpa?a Basin. Additionally, the trapezoidal facets which have been observed on the southern side of the basin indicate that the Kemalpa?a Fault is evolutionally more active as compared to the Spilda?? Fault Zone. The geomorphic indices indicate that the Quaternary landscape evolution of the Kemalpa?a Basin was governed by tectonic and erosional processes, and also the all results of morphometric analysis suggest a relatively high degree of tectonic activity along the faults bounding the Kemalpa?a Basin. Moreover, considering that active large normal faults with an average 15 km long can cause major earthquake, the earthquake hazard in the Kemalpa?a Basin should be investigated in detailed paleoseismological studies.     

Tectonic geomorphology of the easternmost extension of the Gulf of Corinth (Beotia, Central Greece)

The easternmost sector of the Gulf of Corinth, the Beotia area in Central Greece, is an area with active normal faults located between the two major rift structures of Central Greece, the Gulf of Corinth and the North Gulf of Evia. These active normal faults include WNW to E–W and NE to ENE-trending faults affect the landscape and generate basin and range topography within the Beotia. We study four normal fault zones and drainage basin geometry in the easternmost sector of the Gulf of Corinth to document the impact of active tectonics on the landscape evolution. Fault and drainage geometry are investigated based on detailed field mapping and high-resolution digital elevation models. Tectonic geomorphic analysis using several parameters of active tectonics provides information concerning the relative tectonic activity and fault growth. In order to detect areas of lateral stream migration that could indicate recent tectonic activity, the Transverse Topographic Symmetry Factor and the Asymmetry Factor are used to analyse drainage basin geometry in six large drainage basins and a drainage domain covering the study area. Our results show that vertical motions and tilting associated with normal faulting influence the drainage geometry and its development. Values of stream-gradient indices (S_L) are relatively high close to the fault traces of the studied fault zones suggesting high activity. Mountain-front sinuosity (S_mf) mean values along the fault zones ranges from 1.08 to 1.26. Valley floor width to valley height ratios (V_f) mean values along the studied fault zones range between 0.5 and 1.6. Drainage basin shape (B_S) mean values along the fault zones range from 1.08 to 3.54. All these geomorphic parameters and geomorphological data suggest that the analyzed normal faults are highly active. Lateral fault growth was likely produced by primarily eastward propagation, with the WNW to E–W trending faults being the relatively more active structures.     

Holocene coastal response to monsoons and relative sea-level changes in northeast peninsular Malaysia

Sedimentological, geomorphic, and ground penetrating radar (GPR) data are combined with optically stimulated luminescence data to define the Holocene evolution of a coastal system in peninsular Malaysia. The Setiu coastal region of northeast Malaysia comprises five geological and geomorphic units representing distinct evolutionary phases of this coastline. Estimated marine limiting point elevations indicate deposition of an early aggradational shoreline associated with a sea-level elevation of −0.1 to +1.7 m (MSL_PMVGD datum) between ∼6.8 ka and 5.7 ka, in agreement with previous sea-level studies from the Malay–Thai peninsula. A hiatus occurs in the record between ∼5.7 ka and 3.0 ka, possibly due to a relative sea-level oscillation and shoreline erosion. Long-term relative sea-level fall and possible still-stands created strandplains that are interrupted by aggradational to transgressive paleo-barrier and estuary formation corresponding with brief episodes of RSL rise. Analyses of GPR facies and OSL ages suggest annual clinoform deposition, with geometries dictated by variations in ENSO. These data demonstrate the utility of high resolution studies of coastal facies as useful proxy indicators for paleoclimate studies at subdecadal to millennial time-scales.     

Geomorphic evidence for active tectonic deformation in the coastal part of Eastern Black Sea,Eastern Pontides,Turkey

The Eastern Pontides (EP), which is the under transpressional deformation zone, is an active mountain belt that has been rising rapidly since the Cenozoic era because of the Arabian-Eurasian convergence. Morphometric studies have been performed to investigate the tectonic activity of this region and better understand the characteristics of the faults geomorphologically; the faults control the mountain fronts in the drainage basin of the EP. The results show the Hypsometric Curve (HC)-Hypsometric Integral (0.37-HI-0.67), Basin-Shaped Analysis (1.2-B_s-7), Valley-Floor-Width to Height-Ratio (0.4-V_f-1.2) and Asymmetry Factor (35-AF-81) applied to 46 drainage basins together with 9 tectonically controlled geomorphic indices (1.2-S_mf-1.5) and a Stream Length Gradient (30-S_L-120) indicate that the EP is tectonically active, and when the areas are evaluated according to S_mf and V_f analyses, the tectonic level is relatively high. According to our conceptual model for the uplifting of the EP, with respect to field studies and morphometric analysis, (i) the EP is the active deformation zone and has a “push-up” geometry in conjunction with the North Anatolian Fault; (ii) the EP is progressively uplifting at a rate of more than 0.5 mm/yr in along with the thrust faults of the Black Sea Fault (BSF) and Borjomi-Kazbegi Fault (BKF).     

Neotectonic Activity from Karewa Sediments,Kashmir Himalaya,India

Intermontane basin sedimentation occurred during Pliocene-Pleistocene in the Karewa Basin which formed after the continent-continent collision resulting in the formation of Himalayan orogenic belt around Eocene. These are elongated, narrow, thrust bounded basins which have formed during the late stages of orogeny. Situated at a height of 1700–1800 m above sea level, the Karewa basin received sediments because of ponding of a pre-existing river system and the tectonic movements along the Great Himalayan Ranges in the north and the Pir-Panjal ranges in the south along active faults. About 1300 m thick sediments of largely fluvio-lacustrine, glacio-fluvio-lacustrine and eolian origin are exposed having evidences of neotectonically formed structural features such as folds and faults. Folds are more prominent in the Lower Karewa formation (Hirpur Formation) while faults (mostly normal faults) are abundant in the Upper Karewas (Nagum Formation). Drainage in the area varies from dendritic to anastomosing to parallel. Anastomosing drainage suggests sudden decrease in gradient while presence of linear features such as faults and ridges is evident by parallel drainage. Study of morphometric parameters such as stream length (Lsm) and stream length ratios (RL), bifurcation ratio (Rb), drainage density (D), form factor (Rf), circularity ratio (Rc), and elongation ratio (Re) also indicate intense tectonic activity in the recent past.     

Geomorphic and structural evidences of neotectonic activity in the Sub-Himalayan belt of Nahan Salient,NW India

Neotectonism in the Sub-Himalayan belt is not new. Moreover, the word ‘Sub-Himalaya’ is almost synonymous with ‘neotectonic activity’. In the present paper, we report some of the most convincing geomorphic and structural evidences of neotectonic activity from the Sub-Himalayan belt in the Nahan Salient. The geomorphic evidences mainly include the four geomorphic surfaces identified from the transverse topographic profiles drawn parallel to the Himalayan front. These surfaces are commonly covered with terrace deposits that are tilted as well as faulted at a number of places. A number of faults, directly observable in the field, are normal in nature and they are oriented at high angles to the Himalayan Frontal Thrust (HFT). These faults are similar to the E-W extension in southern Tibet in response to the oblique convergence of India at ∼N20°E in the NW Himalaya. They are attributable to the kinematics of neotectonic compression along the HFT, the frontal ramp-oblique ramp-frontal ramp geometry of the thrust fault and related adjustments.     

新构造、活动构造与地震地质

新构造、活动构造和地震地质研究都是开展地震危险性评价的重要基础性地质工作。在综述新构造、活动构造和地震地质的基本含义、相互联系与区别、主要工作内容及方法的基础上,简要回顾了国内外在相关研究领域的主要进展,提出了中国活动构造与地震地质工作中应注意的主要问题和对未来工作的几点建议。最后,重点介绍了青藏高原东南缘开展活动构造体系和玉树地区活动断裂与地震地质调查研究工作所取得的主要进展与成果。