Active tectonics in an area includes ongoing or recent geologic events.This paper investigates the tectonic influence on the subsidence,uplift and tilt of western Saurashtra through morphotectonic analysis of ten wate...Active tectonics in an area includes ongoing or recent geologic events.This paper investigates the tectonic influence on the subsidence,uplift and tilt of western Saurashtra through morphotectonic analysis of ten watersheds along with characteristics of relief and drainage orientation.Watersheds 7-9 to the north(N)are tectonically active,which can be linked with the North Kathiawar Fault System(NKFS)and followed by watersheds 6,10,1,4 and 5.Stream-length gradient index and sinuosity index indicate the effect of tectonic events along the master streams in watersheds 6-9.Higher R^(2)values of the linear curve fit for watershed 7 indicate its master stream is much more tectonically active than the others.The R^(2)curve fitting model and earthquake magnitude/depth analysis confirm the region to be active.The reactivation of the NKFS most likely led to the vertical movement of western Saurashtra.展开更多
Quantitative geomorphic analyses are usually powerful in identifying active tectonics across global orogenic belts.Our present study will focus on the Anatolian Plate which hosts a lot of recent catastrophic earthquak...Quantitative geomorphic analyses are usually powerful in identifying active tectonics across global orogenic belts.Our present study will focus on the Anatolian Plate which hosts a lot of recent catastrophic earthquakes in Türkiye.Six geomorphic indices for 100 sub-basins around Türkiye have been computed including local relief,slope,normalized steepness index(k_(Sn)),hypsometric curve and integral(HI),transverse topographic symmetry factor(Tf),and the basin asymmetry factor(Af).The averaged kSnand Af values have shown four high-value anomalous zones,suggesting relatively high uplift rates featured by high river incision and regional tilting.The values of 0.35≤HI<0.6 for basins with S-shaped curves imply intensive tectonic activities along the eastern part of the North Anatolian Fault Zone(NAFZ),the Northeast Anatolian Fault Zone(NEAFZ),the East Anatolian Fault Zone(EAFZ),and the Central Anatolian Fault Zone(CAFZ).All results of the geomorphic indices analysis suggest a relatively high degree of tectonic activity in the following four areas,the Isparta Angle,the Eastern Black Sea Mountains,the South-eastern Anatolia Region,and the Central Anatolian fault zone.We further suggest that the eastern part of the NAFZ,NEAFZ,EAFZ,and CAFZ will be more active in tectonic activities,with a greater potential for strong earthquake occurrence.展开更多
The Luan River is the most important water system in north-eastern Hebei Province,China and is located in the transitional zone of the Eastern Yan Mountains,North China Plain and Songliao Plain.The well-developed rive...The Luan River is the most important water system in north-eastern Hebei Province,China and is located in the transitional zone of the Eastern Yan Mountains,North China Plain and Songliao Plain.The well-developed river terraces of its tributary,the Yixun River,provide excellent information for studying neotectonics and climate change.There are seven terraces in the lower reaches of the Yixun River,numbered T7-T1.The optically stimulated luminescence dating results of 23 samples show that terraces T7-T2 formed at 111.36±5.83 ka,78.20±4.45 ka,65.29±4.15 ka,56.44±3.07 ka,40.08±2.66 ka,and 13.14±0.76 ka,respectively.A comparison with the oxygen isotope curves of deep-sea sediments reveals that the sediment formation of each terrace corresponded to cold periods of marine isotope stages MIS 4 and MIS 2 and the relatively cold periods of MIS 5e,MIS 3,and MIS 1.Since the Late Pleistocene,the incision rate of the Yixun River has ranged from 0.371-1.740 mm/a.During the formation of T7-T6,T5-T4,T4-T3,and T3-T2,the incision rate was low.However,in the two stages during which T6-T5 and T2-T1 formed(13.14±0.76 ka to 0.58±0.08 ka and 10.79±0.64 ka to 0.16±0.01 ka),these rates reached 1.554 mm/a and 1.592-1.740 mm/a,respectively.At approximately 30 ka,the activity of the Langying Fault increased,leading to footwall uplift.The river gathered in the north of Langying to form the ancient Erdaowan Lake,which resulted in the drying of the river in the lower reaches of the Yixun River during the last glacial maximum without forming river deposits.In the Early Holocene,headward erosion in the lower reaches of the Yixun River was enhanced,which resulted in the disappearance of the lake,and incised meandering formed due to increased neotectonism.Based on the analyses of river incision and the formation of ancient lakes and incised meandering,it was inferred that there have been three periods of strong tectonism in the river basin since the Late Pleistocene.展开更多
The investigation aims to understand how external forces influence tectonic plate movement, causing earthquakes and volcanic eruptions. Our emphasis was on calculating perigee forces at various moon-Earth distances. O...The investigation aims to understand how external forces influence tectonic plate movement, causing earthquakes and volcanic eruptions. Our emphasis was on calculating perigee forces at various moon-Earth distances. Our initial concern is the fluctuating perigee distance between the Moon and Earth. Later, we will cover Earth’s mass fluctuations caused by crustal inhomogeneity. Gravitational force depends on distance and Earth’s mass variations. Wobbling’s Earth and translation around Sun are additional factors. Tidal variations from the Moon trigger subduction zone earthquakes. Volcanoes in the Ring of Fire are influenced by plate movement on fractures and faults.展开更多
The Yaounde Group(YG),representing the southern edge of the North Equatorial PanAfrican Belt,consists of quartzites,schists,micaschists,amphibolites,gneisses and migmatites.Tectonism has formed a landscape characteriz...The Yaounde Group(YG),representing the southern edge of the North Equatorial PanAfrican Belt,consists of quartzites,schists,micaschists,amphibolites,gneisses and migmatites.Tectonism has formed a landscape characterized by the development of linear and folded valleys and ridges,fault scarps,V-shaped valleys,incised rivers and knickpoints.These landforms constitute important markers of the regional tectonic activity,which have been computed from spatial sources such as SRTM,DEM,hydrographical networks and geomorphic indices such as AF,T,Smf,Vf,Bs,Hi,U,SI and Li.The results highlighted a mature relief consisting of asymmetric basins generated by tilting and uplift phenomena.The relative index of active tectonics(RIAT)has been estimated from an average of eight geomorphic indices evaluated on 24 subbasins,in the study area.Four classes have been defined:class 1(1.38),very high active(1.0≤RIAT<1.5);class 2(1.50-1.88),high active(1.5≤RIAT<2.0);and class 3(2.00-2.13)moderate active(2.0≤RIAT<2.5).These three classes,respectively covering 10.20%(458 km2),80.10%(3595 km2)and 9.69%(435 km2)of the study area,have shown a highly active tectonic zone,and imply the existence of a neotectonic event in the YG.This tectonic unit(YG)was also affected by the dextral NW-SE strike-slip faulting,which cross-cut the Sanaga Shear Zone(SSZ)at Ebebda and the foliation oriented NW-SE.The tilting and uplift of rocks related to Moho ascending are responsible for crustal thinning in the Cameroon basement,more important to the Adamawa Plateau from the Cretaceous age and the reactivation of existing tectonic accidents.The presence of hills,fault scarps,reverse faults,knickpoints,V and U shaped valleys and rounded mountains testify to the interaction between tectonic uplift,lithology,climate,weathering and erosion.展开更多
This paper made a numerical simulation to the basic tectonic stress field of Chinese mainland and its neighboringregion using the visco-elasticity finite element model and the new published displacement rate result. M...This paper made a numerical simulation to the basic tectonic stress field of Chinese mainland and its neighboringregion using the visco-elasticity finite element model and the new published displacement rate result. Main contents include the simulation of maximum shear stress and its varying rate, the maximum shear strain and its varyingrate, the shear strain energy density and its varying rate. In view of the high inhomogeneous distribution characterof seismicity in space and time in Chinese mainland and its neighboring area, the normalized background energyvalue was given by means of normalized treatment to the earthquake energy release in the eastern and westernparts of Chinese mainland. And the comparison of the simulation result with the actual seismicity was made. Thefesults show that the simulation values can explain well the earthquake distribution character of Chinese mainlandand its neighboring area.展开更多
On the basis of a 3-dimension visco-elastic finite element model of lithosphere in North China, we numerically simulate the recent mutative figures of tectonic stress field. Annual change characteristics of stress fie...On the basis of a 3-dimension visco-elastic finite element model of lithosphere in North China, we numerically simulate the recent mutative figures of tectonic stress field. Annual change characteristics of stress field are： 1 ） Maximum principal tensile stress is about 3 -9 kPaa-1 and its azimuth lie in NNW-SSE. 2） Maximum principal compressive stress is about 1 - 6 kPaa-1 and its azimuth lie in NEE-SWW. 3 ） Maximum principal tensile stress is higher both in the west region and Liaoning Province. 4） Variation of tectonic stress field benefits fault movement in the west part and northeast part of North China. 5 ）Annual accumulative rates of Coulomb fracture stress in Tanlu fault belt have segmentation patterns： Jiashan-Guangji segment is the high- est （6 kPaa - 1 ） , Anshan-Liaodongwan segment is the second （5 kPaa - l ） , and others are relatively lower （ 3 - 4 kPaa-1 ）.展开更多
The eastern Tibetan plateau has been getting more and more attention because it combines active faults,uplifting, and large earthquakes together in a high-population region. Based on the previous researches, the most ...The eastern Tibetan plateau has been getting more and more attention because it combines active faults,uplifting, and large earthquakes together in a high-population region. Based on the previous researches, the most of Cenozoic tectonic activities were related to the regional structure of the local blocks within the crustal scale. Thus,a better understanding of the crustal structure of the regional tectonic blocks is an important topic for further study. In this paper, we combined the simple Bouguer gravity anomaly with the Moho depths from previous studies to investigate the crustal structure in this area. To highlight the crustal structures, the gravity anomaly caused by the Moho relief has been reduced by forward modeling calculations. A total horizontal derivative（THD） had been applied on the gravity residuals. The results indicated that the crustal gravity residual is compatible with the topography and the geological settings of the regional blocks,including the Sichuan basin, the Chuxiong basin, the Xiaojiang fault, and the Jinhe fault, as well as the Longmenshan fault zone. The THD emphasized the west margin of Yangtze block, i.e., the Longriba fault zone and the Xiaojiang fault cut through the Yangtze block. The checkboard pattern of the gravity residual in the SongpanGarze fold belt and Chuandian fragment shows that the crust is undergoing a southward and SE-directed extrusion,which is coincident with the flowing direction indicatedfrom the GPS measurements. By integrating the interpretations, the stepwise extensional mechanism of the eastern Tibetan plateau is supported by the southeastward crustal deformation, and the extrusion of Chuandian fragment is achieved by Xianshuihe fault.展开更多
The Northern Qilian high-pressure metamorphic belt has experienced multipledeformation-metamorphism, which consists of at least four stages. In 550.8-526 Ma, eclogites wereformed. High temperature and pressure caused ...The Northern Qilian high-pressure metamorphic belt has experienced multipledeformation-metamorphism, which consists of at least four stages. In 550.8-526 Ma, eclogites wereformed. High temperature and pressure caused the escape of a large quantity of gas-liquid fluidsfrom rocks while silicate melt was generated. In the late stage, small amounts of CO_2 and H_2Oinfiltrating along fractures were introduced. In the formation of glaucophane schist (447-362 Ma),devolatilization reactions were dominated during the subduction-uplift stage of the paleoplate. Inthe uplift-exhumation stage (400-380 Ma) the increase of internal space of fractures in the rocksfavoured fluid infiltration and concentration. These fluids participated in hydration reactions inthe retro-metamorphism. The fluids participating in the mineral reactions have the compositions ofCaCl_2-NaCl-H_2O. In subsequent thrusting (<380 Ma), the metamorphic terrain was uplifted to theshallower crust and ductile-shearing deformation took place, which caused mainly dehydrationreactions of minerals. In a near-surface environment the metamorphic terrain experienced brittledeformation, forming many accompanying fractures. Immiscible CO_2 and low-salinity aqueous fluidsoccurred in these secondary microfractures and were trapped and sealed. The thermodynamic conditionsof different deformation-metamorphic stages of the metamorphic terrain were calculated and thecorresponding P-T-t path was deduced, showing that the metamorphic terrain has experienced aclockwise path indicated by T- and P-rising, and T- and P-falling processes. This reveals that thesubduction zone has undergone multiple tectono-dynamic processes, i.e. initial deep burial,subsequent quick uplift and near-surface tectonism.展开更多
The West Anatolia Extensional Zone, which has a width of about 300 km, is located within the Alpine-Himalayan belt and is one of the regions with intense seismic activity in the world. The most important geomorphologi...The West Anatolia Extensional Zone, which has a width of about 300 km, is located within the Alpine-Himalayan belt and is one of the regions with intense seismic activity in the world. The most important geomorphological structures in this area are three main graben structures resulting from regional N-S extension since the Early Miocene. These structures are the E-W trending Büyük Menderes, Kü?ük Menderes, and Gediz grabens. S?ke Basin is located at the SW end of the Büyük Menderes graben. The lineaments which control the NW of S?ke Basin have a length of approximately 40 km and have been defined as the Priene-Sazl? Fault(PSF). The PSF is seismically active, and the last large earthquake(the S?ke-Balat earthquake; Ms: 6.8) was produced on July 16 th of 1955. The ancient city of Priene, which was located in the study area, suffered from destructive earthquakes(in the 4 th century and 2 nd century BC, in the 2 nd century AD, during the Byzantine period and after the 12 th century BC). This study aims to reveal the effect of the PSF on the morphotectonic evolution of the region and the relative tectonic activity of the fault. To this end, it was the first time the stream length gradient index(SL: 130-1303), mountain-front sinuosity(Smf: 1.15-1.96), valley floor height and valley width ratio(Vf: 0.27-1.66), drainage basin asymmetry(AF: 0.15-0.76), hypsometric curve(HC) and hypsometric integral(HI: 0.22-0.86) and basin shape index(Bs: 1.04-5.75) along the mountain front that is formed by the PSF. Using a combination of the mountain-front sinuosity(Smf), valley floor height and valley width ratio(Vf), it is found that the uplift ratio in the region is not less than 0.05 mm/yr and the relative tectonic activity of PSF is high. According to the relative tectonic activity index(Iat) obtained from geomorphic indices, the southwest part of the PSF is relatively more active than the northeast part. As a result, I posit that the PSF has the potential to produce earthquakes in the future similarly to those that were produced in the past, and that the most destructive earthquakes will likely occur on the southwest segments of the fault according to geomorphic indices.展开更多
Based on the research and the division of the active tectonic blocks and their boundaries on the Chinese mainland, the feature of the large earthquake activities on the 24 boundaries between the 6 active tectonic bloc...Based on the research and the division of the active tectonic blocks and their boundaries on the Chinese mainland, the feature of the large earthquake activities on the 24 boundaries between the 6 active tectonic block regions (grade Ⅰ) and the 22 active tectonic blocks (grade Ⅱ) are studied. The seismicity levels on the active tectonic block boundaries are discussed considering the large earthquake frequency and the released strain energy in unit distance and time. The theoretic maximal magnitude and the recurrence period of each boundary are then calculated from the G-R relation. By comparing this with the actual earthquake records, it is found that the intensities of the earthquake deduced from the seismic activity parameter (a/b) on the main active boundaries on the Chinese mainland are consistent with that of the natural earthquakes. Meanwhile, an inverse relation is found between the recurrence periods of large earthquakes and the tectonic motion rate on the boundaries. These results show that the a, b values of each boundary obtained in this paper are valuable. In addition, the present seismic activities and hazards of these boundaries are also probed into with the historical data and their elapsed time on each boundary based on the hypothesis that the large earthquakes satisfy Poisson distribution.展开更多
Based on the hypothesis of the active tectonic blocks on the Chinese continent and its adjacent regions (both the method of the DDA on a spherical surface and the GPS survey results observed from 1991 to 2001 are used...Based on the hypothesis of the active tectonic blocks on the Chinese continent and its adjacent regions (both the method of the DDA on a spherical surface and the GPS survey results observed from 1991 to 2001 are used), the movements and deformations of each active tectonic block are calculated. The calculation results show that although the movements and deformations of active tectonic blocks in the eastern region and in the western region of China are different, active tectonic blocks in the same active tectonic block region are coherent. Then, the relative velocities of the active tectonic blocks’ boundary zones are calculated, and the relationship between current crustal motion and strong seismic activities is discussed. Earthquakes ( M S≥7 0) on the Chinese continent since 1988 all occurred on boundary zones of active tectonic blocks with high slipping speed.展开更多
Morphometry status of tectonic active areas around the Beshagard mountain is as a result of the interaction of neotectonic movements, erosion and subsidence processes. Bashagard mountain contains two attached mountain...Morphometry status of tectonic active areas around the Beshagard mountain is as a result of the interaction of neotectonic movements, erosion and subsidence processes. Bashagard mountain contains two attached mountains (GhaleTohi imountain and Bashagard mountain) with an altitude of 2000 meters at the south of the Jazmurian subsidence surrounded by Quaternary and Neogene. The boundary between the north Makran and Jazmurian subsidence is a fault that located between Band-e-Ziarat unit and western alluvial fan and units of Ganj, Mokhtarabad and Rameshk in the south. Tectonic activity has a significant impact on their morphometry status and drainage basin system. We studied geomorphological patterns of drainage and mountain fronts features for clear changes and high style of mountain. In this study, we studied seven geomorphological indicators for each basin including Vf, Bs, Smf, Sl, Af, RA, Hi between west and south mountain front of Jazmurian. Morphometric indexes were divided in three categories. The average of seven indicators is an index of relative tectonic activity (IRAT). The level of tectonic activity of each IRAT category was determined. Finally, tectonic activity was evaluated for each drainage basin. Results show good similarity between IRAT category and ratio of tectonic activity of the number of drainage basins. The streams profile shows the uplift movement in the western part of subsidence Jazmurian. Thus, the achievements obtained from the analysis of topographic indices, the region’s river system and geomorphological evidence show the movements of uplift and movement of right-lateral strike-slip of Jiroft fault in the west and reverse faulting of Kranj and Jazmurian faults at east of subsidence Jazmurian that all indicates the diagonal tectonic movements.展开更多
In this paper, the baseline variation and displacement vector was analyzed using the calculated results of GPS measurements carried out from 1995 to 1996 in North China. Based on these analytical results, we studied t...In this paper, the baseline variation and displacement vector was analyzed using the calculated results of GPS measurements carried out from 1995 to 1996 in North China. Based on these analytical results, we studied the recent tectonic activity. In general, the regional extension is dominant in the direction of proximately EW, but there is a difference in the SN direction. Extension is significant in the Shanxi fault-depression zone and Bohai region, while compression with strike-slip is characterized along the Yishui-Tancheng segment of the Tanlu fault zone. The baseline shortening zone is distributed along the Baotou-Zhangjiakou-Ninghe areas. It is a boundary zone of regional variation where many differences of crustal horizontal deformation are discovered between the southern part and the northern part of this zone. The baseline shortening zone in NE direction is distributed along the Jianchang-Tangshan-Gucheng area. It is consistent with the Tangshan-Xingtai seismic zone which indicates that展开更多
Decoupling between climate and tectonics, transform the elevation of earth surface regionally by denudation and displacement of land. To extract the tectonic footprints on morphology of landform, geormophometry is wid...Decoupling between climate and tectonics, transform the elevation of earth surface regionally by denudation and displacement of land. To extract the tectonic footprints on morphology of landform, geormophometry is widely accepted tool due to visible responses in Drainage architecture to an intense tectonic environment. The present morphology of Yamuna basin in the Garhwal Himalaya, India is a result of continuing crustal deformation;erosion and deposition in the area. The drainage system and geomorphic expression of topography have been significantly influenced by active tectonics in this basin. In present study, for numerical modelling to detect the influence of tectonic signals on landform, we used morphotectonic parameters, to gradient index (SL), valley floor height to width ratio (Vf), asymmetry factor (Af), basin shape index (BS) and hypsometric integral (HI), extracted from SRTM DEM with resolution of 30 m. All these morphotectonic parameters are integrated to produce an index of relative active tectonics (IRAT). The Yamuna basin is classified into three groups based on IRAT, very high (<2.0);moderate (2.0 - 2.25) and low (>2.25) based on the degree of tectonic activity. Result shows approx. 56% of Yamuna basin experience high tectonic activity. This along strike deformation pattern pronouncedly emulates subsurface geometry based tectonic model.展开更多
Deterministic, probabilistic and composite-grading methods are used to get the possible locations of strong earth-quakes in the future in Norwest Beijing and its vicinity based on the quantitative data and their accur...Deterministic, probabilistic and composite-grading methods are used to get the possible locations of strong earth-quakes in the future in Norwest Beijing and its vicinity based on the quantitative data and their accuracy about active tectonics in the research area and by ordering, some questions in the results are also discussed. It shows that the most dangerous fault segments for strong earthquakes in the future include: segments B and A of the southern boundary fault of the Yangyuan basin, the southern boundary fault of the Xuanhua basin, the east segment of the southern Huaian fault and the east segment of the northern YanggaoTianzhen fault. The most dangerous area is YangyuanShenjing basin, the second one is TianzhenHuaianXuanhua basin and the third dangerous areas are WanquanZhangjiakou and northeast of Yuxian to southwest of Fanshan.展开更多
This paper examines major active faults and the present-day tectonic stress field in the East Tibetan Plateau by integrating available data from published literature and proposes a block kinematics model of the region...This paper examines major active faults and the present-day tectonic stress field in the East Tibetan Plateau by integrating available data from published literature and proposes a block kinematics model of the region. It shows that the East Tibetan Plateau is dominated by strike-slip and reverse faulting stress regimes and that the maximum horizontal stress is roughly consistent with the contemporary velocity field, except for the west Qinling range where it parallels the striking of the major strike-slip faults. Active tectonics in the East Tibetan Plateau is characterized by three faulting systems. The left-slip Kunlun-Qinling faulting system combines the east Kunlun fault zone, sinistral oblique reverse faults along the Minshan range and two major NEE-striking faults cutting the west Qinling range, which accommodates eastward motion, at 10--14 mm/a, of the Chuan-Qing block. The left-slip Xianshuihe faulting system accommodated clockwise rotation of the Chuan-Dian block. The Longmenshan thrust faulting system forms the eastern margin of the East Tibetan Plateau and has been propagated to the SW of the Sichuan basin. Crustal shortening across the Longmenshan range seems low （2-4 mm/a） and absorbed only a small part of the eastward motion of the Chuan-Qing block. Most of this eastward motion has been transmitted to South China, which is moving SEE-ward at 7-9 mm/a. It is suggested from geophysical data interpretation that the crust and lithosphere of the East Tibetan Plateau is considerably thickened and theologically layered. The upper crust seems to be decoupled from the lower crust through a decollement zone at a depth of 15-20 kin, which involved the Longmenshan fault belt and propagated eastward to the SW of the Sichuan basin. The Wenchuan earthquake was just formed at the bifurcated point of this decollement system. A rheological boundary should exist beneath the Longmenshan fault belt where the lower crust of the East Tibetan Plateau and the lithospheric mantle of the Yangze block are juxtaposed.展开更多
Recent studies on the Xianshuihe-Xiaojiang fault system suggest that the Late Quaternary strike-slip rate is approximately uniform along the entire length of the fault zone, about 15±2 mm/a. This approximately un...Recent studies on the Xianshuihe-Xiaojiang fault system suggest that the Late Quaternary strike-slip rate is approximately uniform along the entire length of the fault zone, about 15±2 mm/a. This approximately uniform strike slip rate strongly supports the clockwise rotation model of the southeastern Tibetan crust. By approximating the geometry of the arc-shaped Xianshuihe-Xiaojiang fault system as a portion of a small circle on a spherical Earth, the 15±2 mm/a strike slip rate corresponds to clockwise rotation of the Southeastern Tibetan Block at the （5.2±0.7）×10^-7 deg/a angular velocity around the pole （21°N, 88°E） relative to the Northeast Tibetan Block. The approximately uniform strike slip rate along the Xianshuihe-Xiaojiang fault system also implies that the Longmeushan thrust zone is not active, or at least its activity has been very weak since the Late Quaternary. Moreover, the total offset along the Xiaushuihe-Xiaojiang fault system suggests that the lateral extrusion of the Southeastern Tibetan Block relative to Northeastern Tibetan Block is about 160 km and 200-240 km relative to the Tarim-North China block. This amount of lateral extrusion of the Tibetan crust should have accommodated about 13-24% convergence between India and Eurasia based on mass balance calculations. Assuming that the slip rate of 15±2 mm/a is constant throughout the entire history of the Xianshuihe-Xiaojiang fault system, 11±1.5 Ma is needed for the Xianshuihe-Xiaojiang fault system to attain the 160 km of total offset. This implies that left-slip faulting on the Xianshuihe-Xiaojiang fault system might start at 11±1.5 Ma.展开更多
Ganga river basins exposed to active erosional and deformational processes. The recurrence of landslides, floods, and seismic activities makes it more susceptible to deformational activities. The tectonic analysis usi...Ganga river basins exposed to active erosional and deformational processes. The recurrence of landslides, floods, and seismic activities makes it more susceptible to deformational activities. The tectonic analysis using geomorphic indices and morphometric parameters will help in determining the hazard-prone area of the river basin. Geomorphic indices and morphometric parameters are calculated to investigate the role of neotectonic activities, as it acts as a controlling factor in the development of landforms in the tectonically active terrains. Neotectonic activities influence the terrain topography, which significantly affects the drainage system and geomorphological setup of the area. In this study, the assessment of active tectonics of study area was determined using Advanced Spaceborne Thermal Emission and Reflection Radiometer(ASTER) Global Digital Elevation Model(GDEM) based on Geomorphic Indices(Stream Length Gradient index, Hypsometric integral, Asymmetry factor, Basin shape, Valley floor width to Valley height ratio, Mountain front sinuosity index) cumulatively with Linear, Areal and Relief morphometric parameters on 27 delineated basins of the study area. The combined classification of Relative Tectonic Activity Index(Iat) and morphometric parameters of 27 basins categorized all the zones into four different classes:Class 1 – Very High(<1.97;410 km^2);Class 2 – High(1.97 – 2.05;275 km^2);Class 3 – Moderate(2.05 – 2.21;273 km^2),and Class 4 – Low(>2.21;299 km^2). The basins with tectonic activities have a consistent relationship with structural disturbances, basin geometry, and field studies. The tectonically active zonation of a part of Ganga basin using geomorphic indices and morphometric parameters suggest that it has significant influence of neotectonic activities in a part of Ganga basin.展开更多
基金Research Development Fund(IIT Bombay)supported SM。
文摘Active tectonics in an area includes ongoing or recent geologic events.This paper investigates the tectonic influence on the subsidence,uplift and tilt of western Saurashtra through morphotectonic analysis of ten watersheds along with characteristics of relief and drainage orientation.Watersheds 7-9 to the north(N)are tectonically active,which can be linked with the North Kathiawar Fault System(NKFS)and followed by watersheds 6,10,1,4 and 5.Stream-length gradient index and sinuosity index indicate the effect of tectonic events along the master streams in watersheds 6-9.Higher R^(2)values of the linear curve fit for watershed 7 indicate its master stream is much more tectonically active than the others.The R^(2)curve fitting model and earthquake magnitude/depth analysis confirm the region to be active.The reactivation of the NKFS most likely led to the vertical movement of western Saurashtra.
基金supported by the Key Research and Development Plan of Yunnan Province:The Technology of the Comprehensive Risk Assessment of the Earthquake Catastrophe and the Disaster Chains in Yunnan and Its Application(No.202203AC100003)Institute of Geology,China Earthquake Administration(No.IGCEA2302)。
文摘Quantitative geomorphic analyses are usually powerful in identifying active tectonics across global orogenic belts.Our present study will focus on the Anatolian Plate which hosts a lot of recent catastrophic earthquakes in Türkiye.Six geomorphic indices for 100 sub-basins around Türkiye have been computed including local relief,slope,normalized steepness index(k_(Sn)),hypsometric curve and integral(HI),transverse topographic symmetry factor(Tf),and the basin asymmetry factor(Af).The averaged kSnand Af values have shown four high-value anomalous zones,suggesting relatively high uplift rates featured by high river incision and regional tilting.The values of 0.35≤HI<0.6 for basins with S-shaped curves imply intensive tectonic activities along the eastern part of the North Anatolian Fault Zone(NAFZ),the Northeast Anatolian Fault Zone(NEAFZ),the East Anatolian Fault Zone(EAFZ),and the Central Anatolian Fault Zone(CAFZ).All results of the geomorphic indices analysis suggest a relatively high degree of tectonic activity in the following four areas,the Isparta Angle,the Eastern Black Sea Mountains,the South-eastern Anatolia Region,and the Central Anatolian fault zone.We further suggest that the eastern part of the NAFZ,NEAFZ,EAFZ,and CAFZ will be more active in tectonic activities,with a greater potential for strong earthquake occurrence.
基金supported by the National Natural Science Foundation of China(41977258)the China Geological Survey(DD20190310,DD20221761)the National Key R&D Program of China(2018YFC1504704).
文摘The Luan River is the most important water system in north-eastern Hebei Province,China and is located in the transitional zone of the Eastern Yan Mountains,North China Plain and Songliao Plain.The well-developed river terraces of its tributary,the Yixun River,provide excellent information for studying neotectonics and climate change.There are seven terraces in the lower reaches of the Yixun River,numbered T7-T1.The optically stimulated luminescence dating results of 23 samples show that terraces T7-T2 formed at 111.36±5.83 ka,78.20±4.45 ka,65.29±4.15 ka,56.44±3.07 ka,40.08±2.66 ka,and 13.14±0.76 ka,respectively.A comparison with the oxygen isotope curves of deep-sea sediments reveals that the sediment formation of each terrace corresponded to cold periods of marine isotope stages MIS 4 and MIS 2 and the relatively cold periods of MIS 5e,MIS 3,and MIS 1.Since the Late Pleistocene,the incision rate of the Yixun River has ranged from 0.371-1.740 mm/a.During the formation of T7-T6,T5-T4,T4-T3,and T3-T2,the incision rate was low.However,in the two stages during which T6-T5 and T2-T1 formed(13.14±0.76 ka to 0.58±0.08 ka and 10.79±0.64 ka to 0.16±0.01 ka),these rates reached 1.554 mm/a and 1.592-1.740 mm/a,respectively.At approximately 30 ka,the activity of the Langying Fault increased,leading to footwall uplift.The river gathered in the north of Langying to form the ancient Erdaowan Lake,which resulted in the drying of the river in the lower reaches of the Yixun River during the last glacial maximum without forming river deposits.In the Early Holocene,headward erosion in the lower reaches of the Yixun River was enhanced,which resulted in the disappearance of the lake,and incised meandering formed due to increased neotectonism.Based on the analyses of river incision and the formation of ancient lakes and incised meandering,it was inferred that there have been three periods of strong tectonism in the river basin since the Late Pleistocene.
文摘The investigation aims to understand how external forces influence tectonic plate movement, causing earthquakes and volcanic eruptions. Our emphasis was on calculating perigee forces at various moon-Earth distances. Our initial concern is the fluctuating perigee distance between the Moon and Earth. Later, we will cover Earth’s mass fluctuations caused by crustal inhomogeneity. Gravitational force depends on distance and Earth’s mass variations. Wobbling’s Earth and translation around Sun are additional factors. Tidal variations from the Moon trigger subduction zone earthquakes. Volcanoes in the Ring of Fire are influenced by plate movement on fractures and faults.
文摘The Yaounde Group(YG),representing the southern edge of the North Equatorial PanAfrican Belt,consists of quartzites,schists,micaschists,amphibolites,gneisses and migmatites.Tectonism has formed a landscape characterized by the development of linear and folded valleys and ridges,fault scarps,V-shaped valleys,incised rivers and knickpoints.These landforms constitute important markers of the regional tectonic activity,which have been computed from spatial sources such as SRTM,DEM,hydrographical networks and geomorphic indices such as AF,T,Smf,Vf,Bs,Hi,U,SI and Li.The results highlighted a mature relief consisting of asymmetric basins generated by tilting and uplift phenomena.The relative index of active tectonics(RIAT)has been estimated from an average of eight geomorphic indices evaluated on 24 subbasins,in the study area.Four classes have been defined:class 1(1.38),very high active(1.0≤RIAT<1.5);class 2(1.50-1.88),high active(1.5≤RIAT<2.0);and class 3(2.00-2.13)moderate active(2.0≤RIAT<2.5).These three classes,respectively covering 10.20%(458 km2),80.10%(3595 km2)and 9.69%(435 km2)of the study area,have shown a highly active tectonic zone,and imply the existence of a neotectonic event in the YG.This tectonic unit(YG)was also affected by the dextral NW-SE strike-slip faulting,which cross-cut the Sanaga Shear Zone(SSZ)at Ebebda and the foliation oriented NW-SE.The tilting and uplift of rocks related to Moho ascending are responsible for crustal thinning in the Cameroon basement,more important to the Adamawa Plateau from the Cretaceous age and the reactivation of existing tectonic accidents.The presence of hills,fault scarps,reverse faults,knickpoints,V and U shaped valleys and rounded mountains testify to the interaction between tectonic uplift,lithology,climate,weathering and erosion.
文摘This paper made a numerical simulation to the basic tectonic stress field of Chinese mainland and its neighboringregion using the visco-elasticity finite element model and the new published displacement rate result. Main contents include the simulation of maximum shear stress and its varying rate, the maximum shear strain and its varyingrate, the shear strain energy density and its varying rate. In view of the high inhomogeneous distribution characterof seismicity in space and time in Chinese mainland and its neighboring area, the normalized background energyvalue was given by means of normalized treatment to the earthquake energy release in the eastern and westernparts of Chinese mainland. And the comparison of the simulation result with the actual seismicity was made. Thefesults show that the simulation values can explain well the earthquake distribution character of Chinese mainlandand its neighboring area.
基金supported by research grant from Institute of Crustal Dynamics,China Earthquake Administration(No.ZDJ2009-06)special research grant from Institute of Crustal Dynamics,China Earthquake Administration(No.ZDJ2007-01)
文摘On the basis of a 3-dimension visco-elastic finite element model of lithosphere in North China, we numerically simulate the recent mutative figures of tectonic stress field. Annual change characteristics of stress field are： 1 ） Maximum principal tensile stress is about 3 -9 kPaa-1 and its azimuth lie in NNW-SSE. 2） Maximum principal compressive stress is about 1 - 6 kPaa-1 and its azimuth lie in NEE-SWW. 3 ） Maximum principal tensile stress is higher both in the west region and Liaoning Province. 4） Variation of tectonic stress field benefits fault movement in the west part and northeast part of North China. 5 ）Annual accumulative rates of Coulomb fracture stress in Tanlu fault belt have segmentation patterns： Jiashan-Guangji segment is the high- est （6 kPaa - 1 ） , Anshan-Liaodongwan segment is the second （5 kPaa - l ） , and others are relatively lower （ 3 - 4 kPaa-1 ）.
基金supported by the National Natural Science Foundation of China (Grant Nos.41430213 and 41304064)
文摘The eastern Tibetan plateau has been getting more and more attention because it combines active faults,uplifting, and large earthquakes together in a high-population region. Based on the previous researches, the most of Cenozoic tectonic activities were related to the regional structure of the local blocks within the crustal scale. Thus,a better understanding of the crustal structure of the regional tectonic blocks is an important topic for further study. In this paper, we combined the simple Bouguer gravity anomaly with the Moho depths from previous studies to investigate the crustal structure in this area. To highlight the crustal structures, the gravity anomaly caused by the Moho relief has been reduced by forward modeling calculations. A total horizontal derivative（THD） had been applied on the gravity residuals. The results indicated that the crustal gravity residual is compatible with the topography and the geological settings of the regional blocks,including the Sichuan basin, the Chuxiong basin, the Xiaojiang fault, and the Jinhe fault, as well as the Longmenshan fault zone. The THD emphasized the west margin of Yangtze block, i.e., the Longriba fault zone and the Xiaojiang fault cut through the Yangtze block. The checkboard pattern of the gravity residual in the SongpanGarze fold belt and Chuandian fragment shows that the crust is undergoing a southward and SE-directed extrusion,which is coincident with the flowing direction indicatedfrom the GPS measurements. By integrating the interpretations, the stepwise extensional mechanism of the eastern Tibetan plateau is supported by the southeastward crustal deformation, and the extrusion of Chuandian fragment is achieved by Xianshuihe fault.
文摘The Northern Qilian high-pressure metamorphic belt has experienced multipledeformation-metamorphism, which consists of at least four stages. In 550.8-526 Ma, eclogites wereformed. High temperature and pressure caused the escape of a large quantity of gas-liquid fluidsfrom rocks while silicate melt was generated. In the late stage, small amounts of CO_2 and H_2Oinfiltrating along fractures were introduced. In the formation of glaucophane schist (447-362 Ma),devolatilization reactions were dominated during the subduction-uplift stage of the paleoplate. Inthe uplift-exhumation stage (400-380 Ma) the increase of internal space of fractures in the rocksfavoured fluid infiltration and concentration. These fluids participated in hydration reactions inthe retro-metamorphism. The fluids participating in the mineral reactions have the compositions ofCaCl_2-NaCl-H_2O. In subsequent thrusting (<380 Ma), the metamorphic terrain was uplifted to theshallower crust and ductile-shearing deformation took place, which caused mainly dehydrationreactions of minerals. In a near-surface environment the metamorphic terrain experienced brittledeformation, forming many accompanying fractures. Immiscible CO_2 and low-salinity aqueous fluidsoccurred in these secondary microfractures and were trapped and sealed. The thermodynamic conditionsof different deformation-metamorphic stages of the metamorphic terrain were calculated and thecorresponding P-T-t path was deduced, showing that the metamorphic terrain has experienced aclockwise path indicated by T- and P-rising, and T- and P-falling processes. This reveals that thesubduction zone has undergone multiple tectono-dynamic processes, i.e. initial deep burial,subsequent quick uplift and near-surface tectonism.
文摘The West Anatolia Extensional Zone, which has a width of about 300 km, is located within the Alpine-Himalayan belt and is one of the regions with intense seismic activity in the world. The most important geomorphological structures in this area are three main graben structures resulting from regional N-S extension since the Early Miocene. These structures are the E-W trending Büyük Menderes, Kü?ük Menderes, and Gediz grabens. S?ke Basin is located at the SW end of the Büyük Menderes graben. The lineaments which control the NW of S?ke Basin have a length of approximately 40 km and have been defined as the Priene-Sazl? Fault(PSF). The PSF is seismically active, and the last large earthquake(the S?ke-Balat earthquake; Ms: 6.8) was produced on July 16 th of 1955. The ancient city of Priene, which was located in the study area, suffered from destructive earthquakes(in the 4 th century and 2 nd century BC, in the 2 nd century AD, during the Byzantine period and after the 12 th century BC). This study aims to reveal the effect of the PSF on the morphotectonic evolution of the region and the relative tectonic activity of the fault. To this end, it was the first time the stream length gradient index(SL: 130-1303), mountain-front sinuosity(Smf: 1.15-1.96), valley floor height and valley width ratio(Vf: 0.27-1.66), drainage basin asymmetry(AF: 0.15-0.76), hypsometric curve(HC) and hypsometric integral(HI: 0.22-0.86) and basin shape index(Bs: 1.04-5.75) along the mountain front that is formed by the PSF. Using a combination of the mountain-front sinuosity(Smf), valley floor height and valley width ratio(Vf), it is found that the uplift ratio in the region is not less than 0.05 mm/yr and the relative tectonic activity of PSF is high. According to the relative tectonic activity index(Iat) obtained from geomorphic indices, the southwest part of the PSF is relatively more active than the northeast part. As a result, I posit that the PSF has the potential to produce earthquakes in the future similarly to those that were produced in the past, and that the most destructive earthquakes will likely occur on the southwest segments of the fault according to geomorphic indices.
基金The work was supported bythe public welfare programofthe Ministry of Science and Technology of China (2004DIA3J010)the special preparatoryresearch of national keyfun-damental research project (2002CCD01700)the Young Scientists Funds of Institute of Earthquake Science , CEA(QN200401) .
文摘Based on the research and the division of the active tectonic blocks and their boundaries on the Chinese mainland, the feature of the large earthquake activities on the 24 boundaries between the 6 active tectonic block regions (grade Ⅰ) and the 22 active tectonic blocks (grade Ⅱ) are studied. The seismicity levels on the active tectonic block boundaries are discussed considering the large earthquake frequency and the released strain energy in unit distance and time. The theoretic maximal magnitude and the recurrence period of each boundary are then calculated from the G-R relation. By comparing this with the actual earthquake records, it is found that the intensities of the earthquake deduced from the seismic activity parameter (a/b) on the main active boundaries on the Chinese mainland are consistent with that of the natural earthquakes. Meanwhile, an inverse relation is found between the recurrence periods of large earthquakes and the tectonic motion rate on the boundaries. These results show that the a, b values of each boundary obtained in this paper are valuable. In addition, the present seismic activities and hazards of these boundaries are also probed into with the historical data and their elapsed time on each boundary based on the hypothesis that the large earthquakes satisfy Poisson distribution.
文摘Based on the hypothesis of the active tectonic blocks on the Chinese continent and its adjacent regions (both the method of the DDA on a spherical surface and the GPS survey results observed from 1991 to 2001 are used), the movements and deformations of each active tectonic block are calculated. The calculation results show that although the movements and deformations of active tectonic blocks in the eastern region and in the western region of China are different, active tectonic blocks in the same active tectonic block region are coherent. Then, the relative velocities of the active tectonic blocks’ boundary zones are calculated, and the relationship between current crustal motion and strong seismic activities is discussed. Earthquakes ( M S≥7 0) on the Chinese continent since 1988 all occurred on boundary zones of active tectonic blocks with high slipping speed.
文摘Morphometry status of tectonic active areas around the Beshagard mountain is as a result of the interaction of neotectonic movements, erosion and subsidence processes. Bashagard mountain contains two attached mountains (GhaleTohi imountain and Bashagard mountain) with an altitude of 2000 meters at the south of the Jazmurian subsidence surrounded by Quaternary and Neogene. The boundary between the north Makran and Jazmurian subsidence is a fault that located between Band-e-Ziarat unit and western alluvial fan and units of Ganj, Mokhtarabad and Rameshk in the south. Tectonic activity has a significant impact on their morphometry status and drainage basin system. We studied geomorphological patterns of drainage and mountain fronts features for clear changes and high style of mountain. In this study, we studied seven geomorphological indicators for each basin including Vf, Bs, Smf, Sl, Af, RA, Hi between west and south mountain front of Jazmurian. Morphometric indexes were divided in three categories. The average of seven indicators is an index of relative tectonic activity (IRAT). The level of tectonic activity of each IRAT category was determined. Finally, tectonic activity was evaluated for each drainage basin. Results show good similarity between IRAT category and ratio of tectonic activity of the number of drainage basins. The streams profile shows the uplift movement in the western part of subsidence Jazmurian. Thus, the achievements obtained from the analysis of topographic indices, the region’s river system and geomorphological evidence show the movements of uplift and movement of right-lateral strike-slip of Jiroft fault in the west and reverse faulting of Kranj and Jazmurian faults at east of subsidence Jazmurian that all indicates the diagonal tectonic movements.
基金This project was sponsored by the Commission of Science, Technology, and Industry for National Defence (94)1-D1, China.
文摘In this paper, the baseline variation and displacement vector was analyzed using the calculated results of GPS measurements carried out from 1995 to 1996 in North China. Based on these analytical results, we studied the recent tectonic activity. In general, the regional extension is dominant in the direction of proximately EW, but there is a difference in the SN direction. Extension is significant in the Shanxi fault-depression zone and Bohai region, while compression with strike-slip is characterized along the Yishui-Tancheng segment of the Tanlu fault zone. The baseline shortening zone is distributed along the Baotou-Zhangjiakou-Ninghe areas. It is a boundary zone of regional variation where many differences of crustal horizontal deformation are discovered between the southern part and the northern part of this zone. The baseline shortening zone in NE direction is distributed along the Jianchang-Tangshan-Gucheng area. It is consistent with the Tangshan-Xingtai seismic zone which indicates that
文摘Decoupling between climate and tectonics, transform the elevation of earth surface regionally by denudation and displacement of land. To extract the tectonic footprints on morphology of landform, geormophometry is widely accepted tool due to visible responses in Drainage architecture to an intense tectonic environment. The present morphology of Yamuna basin in the Garhwal Himalaya, India is a result of continuing crustal deformation;erosion and deposition in the area. The drainage system and geomorphic expression of topography have been significantly influenced by active tectonics in this basin. In present study, for numerical modelling to detect the influence of tectonic signals on landform, we used morphotectonic parameters, to gradient index (SL), valley floor height to width ratio (Vf), asymmetry factor (Af), basin shape index (BS) and hypsometric integral (HI), extracted from SRTM DEM with resolution of 30 m. All these morphotectonic parameters are integrated to produce an index of relative active tectonics (IRAT). The Yamuna basin is classified into three groups based on IRAT, very high (<2.0);moderate (2.0 - 2.25) and low (>2.25) based on the degree of tectonic activity. Result shows approx. 56% of Yamuna basin experience high tectonic activity. This along strike deformation pattern pronouncedly emulates subsurface geometry based tectonic model.
基金National major basic-theory planning project Mechanism and Prediction of Strong Earthquake (95130105) and the Key Project from China Seismological Bureau (95040803).
文摘Deterministic, probabilistic and composite-grading methods are used to get the possible locations of strong earth-quakes in the future in Norwest Beijing and its vicinity based on the quantitative data and their accuracy about active tectonics in the research area and by ordering, some questions in the results are also discussed. It shows that the most dangerous fault segments for strong earthquakes in the future include: segments B and A of the southern boundary fault of the Yangyuan basin, the southern boundary fault of the Xuanhua basin, the east segment of the southern Huaian fault and the east segment of the northern YanggaoTianzhen fault. The most dangerous area is YangyuanShenjing basin, the second one is TianzhenHuaianXuanhua basin and the third dangerous areas are WanquanZhangjiakou and northeast of Yuxian to southwest of Fanshan.
基金the auspice of National Key Basic Project(973)(granted number 2008CB425702)National Science and Technology Project(granted Number SinoProbe-08)China Geological Survey project(granted number1212010670104)
文摘This paper examines major active faults and the present-day tectonic stress field in the East Tibetan Plateau by integrating available data from published literature and proposes a block kinematics model of the region. It shows that the East Tibetan Plateau is dominated by strike-slip and reverse faulting stress regimes and that the maximum horizontal stress is roughly consistent with the contemporary velocity field, except for the west Qinling range where it parallels the striking of the major strike-slip faults. Active tectonics in the East Tibetan Plateau is characterized by three faulting systems. The left-slip Kunlun-Qinling faulting system combines the east Kunlun fault zone, sinistral oblique reverse faults along the Minshan range and two major NEE-striking faults cutting the west Qinling range, which accommodates eastward motion, at 10--14 mm/a, of the Chuan-Qing block. The left-slip Xianshuihe faulting system accommodated clockwise rotation of the Chuan-Dian block. The Longmenshan thrust faulting system forms the eastern margin of the East Tibetan Plateau and has been propagated to the SW of the Sichuan basin. Crustal shortening across the Longmenshan range seems low （2-4 mm/a） and absorbed only a small part of the eastward motion of the Chuan-Qing block. Most of this eastward motion has been transmitted to South China, which is moving SEE-ward at 7-9 mm/a. It is suggested from geophysical data interpretation that the crust and lithosphere of the East Tibetan Plateau is considerably thickened and theologically layered. The upper crust seems to be decoupled from the lower crust through a decollement zone at a depth of 15-20 kin, which involved the Longmenshan fault belt and propagated eastward to the SW of the Sichuan basin. The Wenchuan earthquake was just formed at the bifurcated point of this decollement system. A rheological boundary should exist beneath the Longmenshan fault belt where the lower crust of the East Tibetan Plateau and the lithospheric mantle of the Yangze block are juxtaposed.
基金supported mainly by the National Key Basic Research Program(No.2004CB418401)the National Natural Science Foundation of China(grant No.40472109)+1 种基金partly from the Joint Earthquake Science Foundation of China(grant No.105066)the SASAKAWA Scientific Grant from the Japan Science Society.
文摘Recent studies on the Xianshuihe-Xiaojiang fault system suggest that the Late Quaternary strike-slip rate is approximately uniform along the entire length of the fault zone, about 15±2 mm/a. This approximately uniform strike slip rate strongly supports the clockwise rotation model of the southeastern Tibetan crust. By approximating the geometry of the arc-shaped Xianshuihe-Xiaojiang fault system as a portion of a small circle on a spherical Earth, the 15±2 mm/a strike slip rate corresponds to clockwise rotation of the Southeastern Tibetan Block at the （5.2±0.7）×10^-7 deg/a angular velocity around the pole （21°N, 88°E） relative to the Northeast Tibetan Block. The approximately uniform strike slip rate along the Xianshuihe-Xiaojiang fault system also implies that the Longmeushan thrust zone is not active, or at least its activity has been very weak since the Late Quaternary. Moreover, the total offset along the Xiaushuihe-Xiaojiang fault system suggests that the lateral extrusion of the Southeastern Tibetan Block relative to Northeastern Tibetan Block is about 160 km and 200-240 km relative to the Tarim-North China block. This amount of lateral extrusion of the Tibetan crust should have accommodated about 13-24% convergence between India and Eurasia based on mass balance calculations. Assuming that the slip rate of 15±2 mm/a is constant throughout the entire history of the Xianshuihe-Xiaojiang fault system, 11±1.5 Ma is needed for the Xianshuihe-Xiaojiang fault system to attain the 160 km of total offset. This implies that left-slip faulting on the Xianshuihe-Xiaojiang fault system might start at 11±1.5 Ma.
文摘Ganga river basins exposed to active erosional and deformational processes. The recurrence of landslides, floods, and seismic activities makes it more susceptible to deformational activities. The tectonic analysis using geomorphic indices and morphometric parameters will help in determining the hazard-prone area of the river basin. Geomorphic indices and morphometric parameters are calculated to investigate the role of neotectonic activities, as it acts as a controlling factor in the development of landforms in the tectonically active terrains. Neotectonic activities influence the terrain topography, which significantly affects the drainage system and geomorphological setup of the area. In this study, the assessment of active tectonics of study area was determined using Advanced Spaceborne Thermal Emission and Reflection Radiometer(ASTER) Global Digital Elevation Model(GDEM) based on Geomorphic Indices(Stream Length Gradient index, Hypsometric integral, Asymmetry factor, Basin shape, Valley floor width to Valley height ratio, Mountain front sinuosity index) cumulatively with Linear, Areal and Relief morphometric parameters on 27 delineated basins of the study area. The combined classification of Relative Tectonic Activity Index(Iat) and morphometric parameters of 27 basins categorized all the zones into four different classes:Class 1 – Very High(<1.97;410 km^2);Class 2 – High(1.97 – 2.05;275 km^2);Class 3 – Moderate(2.05 – 2.21;273 km^2),and Class 4 – Low(>2.21;299 km^2). The basins with tectonic activities have a consistent relationship with structural disturbances, basin geometry, and field studies. The tectonically active zonation of a part of Ganga basin using geomorphic indices and morphometric parameters suggest that it has significant influence of neotectonic activities in a part of Ganga basin.
