tectonic forcing of drainages and geomorphic features developed across himalayan mountain frontal part of western limb of siang antiform arunachal himalaya drainages display tectonic forcing of their channels on the frontal region of the arunachal himalaya due to structural control dikari a transverse river flowing along the n s trending western limb of the major siang antiform exhibits structurally controlled nature of its drainage on its downstream flow towards south through a network of ne sw and nw se trending conjugate faults the river shows compressed meandering as the regional structural trend of ene wsw seems to be reactivated by the transverse nw se trend of neotectonic fault activity the himalayan frontal thrust hft tracing along the himalaya mountain front has been displaced sinisterly for a distance of 7 km by a wnw ese trending fault running along the sileng stream development of parallel drainages in the southern part of the sub himalaya is interpreted to have formed as a result of uplifting related to the above mentioned strike slip movement along the hft zone the frontal streams and rivers exhibit deflection of their channels from ne sw to ene wsw directions channel of the transverse siang river has been deflected for a length of 3 km along the nne ssw direction across the himalayan frontal part in this part of the himalaya previous workers did not give much emphasis on the role of siang antiform as far as neotectonic with respect to the tectonics related to the hft is concerned there is a syntectonic relationship between the active ne sw oriented compression direction and the tectonic forcing of the drainages including development of the tectonic geomorphology

uplift and convergence along the himalayan frontal thrust of india along the himalayan thrust front in northwestern india terrace deposits exposed 20 to 30 m above modern stream level are interpreted to have been uplifted by displacement on the underlying himalayan frontal thrust a radiocarbon age limits the age of the terrace to 1665 215 calendar bc 3663 215 radiocarbon years before present yielding a vertical uplift rate of 6 9 1 8 mm yr in combination with published studies constraining the dip of the himalayan frontal thrust fault to about 30 in the study area the observed uplift rate equates to horizontal shortening across the himalayan frontal thrust of 11 9 3 1 mm yr and the slip rate of the himalayan frontal thrust of 13 8 3 6 mm yr this is similar to previously reported rate estimates along the himalayan arc based on displacement of older plio miocene age rocks or the much shorter records of geodesy and historical seismicity the similarity is consistent with the idea that convergence across the himalayan front has occurred at a relatively steady rate through time the seismic expression of this deformation includes several great m 8 historical earthquakes which due to lack of surface rupture during those events have been attributed to their occurrence on blind thrusts yet the occurrence of a possible fault scarp in the field area indicates that past earthquakes have been sufficiently large to rupture to the surface and produce coseismic scarps these observations suggest a potential for earthquakes along the himalayan frontal thrust larger than those observed historically

the strength and deformation behaviour of model adfreeze and grouted piles in saline frozen soils the results of a laboratory study to determine the influence of soil salinity pile surface treatment pile backfill material and temperature on the adfreeze bond strength and deformation of model

slip distribution beneath the central and western himalaya inferred from gps observations summary underthrusting of the indian plate beneath the himalaya has been the cause of many hazardous thrust faulting earthquakes along the arc moderate earthquakes with magnitudes of 5 occur frequently in this region releasing the elastic strain accumulated over many years around the plate boundary these events can be attributed to slip deficits where the indian and eurasian plates are locked during interseismic periods geodetic measurements can help discriminate the distribution of the interlocking areas and the steadily slipping areas beneath the himalaya to understand the deformation across the central and western himalaya and the associated slip on thrust faults campaign mode gps data were collected in the garhwal kumaun region of the western himalaya gps sites velocities show that the deformation is currently concentrated between the lesser and higher himalaya horizontal velocities are used to estimate the slip distribution for the estimation a model of the interseismic surface deformation caused by buried non uniform creep dislocation nuc on a curved fault surface is used the slip distribution shows that there might be structural discontinuity on the fault between the kumaun and garhwal regions of the himalaya the estimated slip rate at the depth around 20 40 km in the central himalaya and at the depth of 15 km in the western himalaya is 10 mm yr 1 the nuc model indicates that the shallow part 20 km of the thrust fault system along the plate boundary is almost locked the locking depth appears to be deep in the central himalaya and shallower in the western himalaya further most of the historical large seismic events are observed to have occurred in an area with a slip velocity less than 10 mm yr 1 i e in a locked zone at the plate interface

field pile load tests in saline permafrost i test procedures and results a pile load test program carried out in iqaluit northwest territories to provide design information for the short range radar sites is described the program consisted of testing 10 steel pipe pi

landscape response to tectonic forcing digital elevation model analysis of stream profiles in the mendocino triple junction region northern california the topographic evolution of orogens is fundamentally dictated by rates and patterns of bedrock channel incision quantitative field assessments of process based laws are needed to accurately describe landscape uplift and denudation in response to tectonics and climate we evaluate and calibrate the shear stress or similar unit stream power bedrock incision model by studying stream profiles in a tectonically active mountain range previous work on emergent marine terraces in the mendocino triple junction region of northern california provides spatial and temporal control on rock uplift rates digital elevation models and field data are used to quantify differences in landscape morphology associated with along strike northwest to southeast changes in tectonic and climatic conditions analysis of longitudinal profiles supports the hypothesis that the study area channels are in equilibrium with current uplift and climatic conditions consistent with theoretical calculations of system response time based on the shear stress model within uncertainty the profile concavity of the trunk streams is constant throughout the study area 0 43 as predicted by the model channel steepness correlates with uplift rate these data help constrain the two key unknown model parameters the coefficient of erosion k and the exponent associated with channel gradient n this analysis shows that k cannot be treated as a constant throughout the study area despite generally homogeneous substrate properties for a reasonable range of slope exponent values n best fit values of k are positively correlated with uplift rate this correlation has important implications for landscape evolution models and likely reflects dynamic adjustment of k to tectonic changes due to variations in orographic precipitation and perhaps channel width sediment load and frequency of debris flows the apparent variation in k makes a unique value of n impossible to constrain with present data

first order kinematics of wedge scale active himalayan deformation insights from darjiling sikkim tibet dasit wedge abstract the indian plate has collided with the eurasian plate along an arcuate boundary over the last 55 60 million years defining the himalayan mountain belt the geometry of the collision boundary is wedge shaped the base of this wedge is defined by a decollement named the main himalayan thrust mht in the darjiling sikkim tibet dasit himalayan wedge a crustal scale fault bend fold kangmar anticline and the lesser himalayan duplex lhd are dominant structures that have built taper and controlled the foreland ward propagation of the thrust sheets a frontal physiographic half window has eroded through the main central thrust mct sheet to expose the lhd in the dasit wedge preliminary data suggest that active tectonics and seismicity in the dasit wedge may be concentrated in the half window this suggests that lhd may be an active structure high precision global positioning system measurements in the dasit wedge suggest that a minimum of 12 mm yr convergence is being accommodated in the darjiling sikkim himalaya out of which 4 mm yr convergence is being taken up in the lhd given that decollement earthquakes with minimum internal deformation in a deforming wedge occur when it attains critical taper continued deformation within the dasit wedge and the lack of great decollement earthquakes indicate that the dasit himalayan wedge is presently sub critical and in the process of building taper the sub critical nature of the dasit wedge is probably the result of low topographic and decollement slopes weaker rocks and pronounced erosion in the frontal part of the wedge

geologic correlation of the himalayan orogen and indian craton part 2 structural geology geochronology and tectonic evolution of the eastern himalaya despite being the largest active collisional orogen on earth the growth mechanism of the himalaya remains uncertain current debate has focused on the role of dynamic interaction between tectonics and climate and mass exchanges between the himalayan and tibetan crust during cenozoic india asia collision a major uncertainty in the debate comes from the lack of geologic information on the eastern segment of the himalayas from 91 e to 97 e which makes up about one quarter of the mountain belt to address this issue we conducted detailed field mapping u pb zircon age dating and 40ar 39ar thermochronology along two geologic traverses at longitudes of 92 e and 94 e across the eastern himalaya our dating indicates the region experienced magmatic events at 1745 1760 ma 825 878 ma 480 520 ma and 28 20 ma the first three events also occurred in the northeastern indian craton while the last is unique to the himalaya correlation of magmatic events and age equivalent lithologic units suggests that the eastern segment of the himalaya was constructed in situ by basement involved thrusting which is inconsistent with the hypothesis of high grade himalaya rocks derived from tibet via channel flow the main central thrust in the eastern himalaya forms the roof of a major thrust duplex its northern part was initiated at ca 13 ma while the southern part was initiated at ca 10 ma as indicated by 40ar 39ar thermochronometry crustal thickening of the main central thrust hanging wall was expressed by discrete ductile thrusting between 12 ma and 7 ma overlapping in time with motion on the main central thrust below restoration of two possible geologic cross sections from one of our geologic traverses where one assumes the existence of pre cenozoic deformation below the himalaya and the other assumes flat lying strata prior to the india asia collision leads to estimated shortening of 775 km 76 strain and 515 km 70 strain respectively we favor the presence of significant basement topography below the eastern himalaya based on projections of early paleozoic structures from the shillong plateau i e the central shillong thrust located 50 km south of our study area since northeastern india and possibly the eastern himalaya both experienced early paleozoic contraction the estimated shortening from this study may have resulted from a combined effect of early paleozoic and cenozoic deformation

microearthquake activity in some parts of the himalaya and the tectonic model abstract microearthquake data from temporary permanent networks in different parts of the himalaya shed new light on understanding the earthquake generating processes and their relation to tectonic models of the region the microearthquake activity in arunachal pradesh northeastern himalaya is found to be pronounced at the main boundary thrust mbt and to its south the subcrustal earthquakes depth 50 80 km occur much below the plane of detachment of the tectonic models proposed by seeber et al 1981 ni and barazangi 1984 the mbt is not the seismogenic fault the earthquakes are generated by strike slip movement on deep seated hidden faults transverse to the mbt the high seismic activity in the shillong plateau about 200 km south of the mbt in the northeast region is due to the influence of himalayan collision tectonics to the north and burmese arc subduction tectonics to the east the activity in the plateau is not directly related to the himalayan thrust belt or seismic belt these are mostly crustal earthquakes depth 10 30 km and are caused by local active faults lineaments in the eastern himalaya in the sikkim and darjeeling area the seismic activity is found to be clustered mostly to the north of the mbt the earthquakes occur at a depth range 0 50 km the majority of them occur below the detachment plane by thrust faulting in the central part in the nepal himalaya lateral variations of the seismic activity are observed which represent lateral segmentation of the mbt by transverse tectonic features in the western himalaya however the tectonic models fit well with the microearthquake data in the himachal pradesh of the western himalaya the microearthquakes are mostly recorded in the mbt zone and the hypocentres depth 0 20 km are confined above the plane of detachment or on the basement thrust the earthquakes mostly occur to the south of the main central thrust mct which suggests that the mct is not seismogenic it is rather a dormant fault no single tectonic model explains the himalayan earthquakes

effect of backfill properties and surface treatment on the capacity of adfreeze pipe piles this note presents the results of a limited number of laboratory scale pile load tests to establish those modifications to current pile construction procedures that would be most effective in increasing pile capacity the results indicate that the properties of the backfill ice content salinity and size of annulus have a significant influence on short term pile capacity while the properties of the native soil are less important the results demonstrate that the pile capacity can be maximized through the use of nonsaline sand backfill in saline soils the shear strength at the backfill native soil interface may govern the design and must be evaluated together with the adfreeze strength at the pile backfill interface the results also demonstrate that the roughness of the outside surface of the pile has a significant influence on adfreeze strength sandblasting the pile surface doubled the adfreeze strength at the pipe backfill interface this effect appears to be due to increased surface roughness rather than to the removal of paint from the pile surface

morpho sedimentary records at the brahmaputra river exit ne himalaya climate tectonic interplay during the late pleistocene holocene morphological and sedimentary records at the exit of brahmaputra river at pasighat in the ne himalaya inform about the climate tectonic interplay during the past ca 15 ka the geomorphology of the area comprises 1 fan terrace t3 2 a high angle fan 3 terrace t2 4 terrace t1 and 5 a low angle fan geomorphic consideration suggests that the fan terrace t3 and high angle fans are the oldest units and were coeval the low angle fan is the youngest geomorphic unit sedimentological studies and optically stimulated luminescence chronology suggest that i fan terrace t3 formed between 13 and 10 5 ka and comprised multiple events of debris flows separated by the aggradation as channel bars in a braided river environment ii the high angle fan formed during 15 10 ka and comprises channel bar aggradation in braided river conditions iii terrace t2 formed during 10 8 ka due to aggradation in a braided channel environment with lesser events of debris flows iv terrace t1 formed during 7 and 3 ka took place as bars of the braided river sudden coarsening of the sediment indicated a tectonic rejuvenation in the provenance region between 7 and 3 ka and v the low angle fans dated to 3 ka formed due to aggradation in a small tributary joining the brahmaputra river this implies a phase when the main channel of the brahmaputra did not flood regularly and the tributaries were actively aggrading the sedimentation style and incision of these geomorphic units responded to contemporary climatic changes and uplift in the siwalik range along the himalayan frontal fault copyright 2008 john wiley sons ltd

estimates of interseismic deformation in northeast india from gps measurements abstract estimates of interseismic deformation in northeastern india based on gps measurements at eight permanent stations 2003 2006 and six campaign sites 1997 2006 are presented here the euler pole of rotation of indian tectonic plate in itrf2000 determined from the present data set is located at 51 7 0 5 n 15 1 1 5 e with angular velocity of 0 469 0 01 myr 1 the results show that there is a statistically insignificant present day active deformation within the shillong plateau and in the foreland spur north of the plateau in the brahmaputra valley convergence rate of the northeastern gps sites with respect to the igs station lhasa along baselines that are normal to the himalayan arc in this region is 16 0 5 mm yr this represents the arc normal indo eurasian convergence rate across the northeastern boundary similar to arc normal convergence rates determined in central nepal along the himalayan arc however unlike central nepal in the arunachal himalaya the 16 mm yr shortening is distributed between the lesser as well as higher and tethyan himalayas baselines between sites on the indo burmese fold and thrust belt ibftb and shillong plateau indicate variations in the shortening rate from 1 5 mm yr on the tripura mizoram salient trs south of the plateau to 6 mm yr in the imphal recess ir to the east and 8 mm yr in naga salient ns to the northeast this suggests that the deformation in the ibftb is segmented into n s blocks along e w transverse zones exhibiting dextral slip between ns ir and sinistral slip between ir and trs baselines between the ibftb sites also show 10 0 6 mm yr convergence pointing to the existence of an active transverse zone between aizawl and imphal

timing of recent out of sequence active deformation in the frontal himalayan wedge insights from the darjiling sub himalaya india recent studies of india eurasia convergence suggest that the entire convergence in the himalayan wedge is almost exclusively accommodated along its basal detachment fault main himalayan thrust mht and its near surface equivalent main frontal thrust mft using direct dating of fault zone gouge and strath terrace deposits we conclude the following 1 the present mountain front in the darjiling sub himalaya was emplaced by ca 40 ka 2 out of sequence deformation on surface breaking faults north of the mft in the darjiling sub himalaya began ca 20 ka and has probably continued since 3 the tista river responded to the ca 20 ka deformation by migrating 150 m eastward average rate 13 mm yr 1 and by incising 48 m vertically average rate 4 4 mm yr 1 creating unpaired disjointed strath terraces between 11 3 1 3 ka and 1 4 0 3 ka out of sequence surface breaking faults in the himalaya indicate partial accommodation of active convergence within the himalayan wedge using the results from the bhuj earthquake of 2001 we suggest that active deformation along the out of sequence faults is a potential seismic hazard in the himalaya and himalayan seismic hazard models must account for this we also propose a conceptual model for active deformation in the himalaya

tectonic implication of drainage set up in the sub himalaya a case study of papumpare district arunachal himalaya india abstract the sub himalaya deformed between the main boundary thrust and or bomdila thrust towards north and the himalayan frontal thrust hft towards south is characterized by the presence of fault propagated folds and an imbricate thrust system along the hft the mountain front is offset for about 10 km sinistrally along a nw se trending transverse fault the banderdewa fault which runs through the dikrang river valley that seems to have followed a pull apart basin developed along the banderdewa fault the western part of study area associated with a major folding faulting and the development of fault bounded quaternary basins with normal faulting along their northern margins is interpreted to be tectonically more transported towards southeast than the eastern part where no quaternary basins are developed the channel forms and landforms have been studied in relation to the neotectonics of the area the watersheds exhibit their structurally controlled nature with drainages following tectonic alignments rivers streams experienced compressed meandering narrowing widening and deflection of channels longitudinal profiles of river stream channels exhibit knick points unpaired terraces are observed at higher levels factors like the unconsolidated siwalik rocks tectonic instability along faults and high rainfall with the advent of the holocene led to the development of the present day drainage set up a tectonic model is proposed for development of tectonic geomorphology of the area influenced by ultra tremor to low magnitude earthquakes in seismically very active northeastern india as moderate to big earthquakes m 6 0 are scarce in this region

paleoseismic evidence of great surface rupture earthquakes along the indian himalaya 1 toward understanding the relationship between strain accumulation and strain release in the context of the mechanics of the earthquake and mountain building process and quantifying the seismic hazard associated with the globes largest continental thrust system we describe the late quaternary expression and paleoseismic evidence for great surface rupture earthquakes at six sites along the himalayan frontal thrust hft system of india our observations span a distance of 250 km along strike of the hft uplifted and truncated fluvial terrace deposits resulting from the holocene displacements on the hft are preserved along canyons of the ghaggar markanda shajahanpur and kosi rivers dividing the elevation of the bedrock straths at each site by their ages yields estimates of the vertical uplift rate of 4 6 mm yr which when assumed to be the result of slip on an underlying thrust dipping at 20 45 are equivalent to fault slip rates of 6 18 mm yr or shortening rates of 4 16 mm yr trench exposures reveal the hft to fold and break late holocene surface sediments near the cities and villages of chandigarh kala amb rampur ganda lal dhang and ramnagar radiocarbon ages of samples obtained from the displaced sediments indicate surface rupture at each site took place after a d 1200 and before a d 1700 uncertainties attendant to the radiocarbon dating currently do not allow an unambiguous definition of the capping bound on the age of the displacement at each site and hence whether or not the displacements at all sites were contemporaneous trench exposures and vertical separations measured across scarps at rampur ganda lal dhang and ramnagar are interpreted to indicate single event displacements of 11 38 m dividing the observed single event vertical components of displacement by the estimated longer term uplift rates indicates 1330 3250 or more years should be required to accumulate the slip sufficient to produce similar sized displacements surface rupture appears to not have occurred during the historical 1905 kangra mw 7 7 1934 bihar nepal mw 8 1 and 1950 assam mw 8 4 earthquakes which also occurred along the himalayan front yet we observe clear evidence of fault scarps and displacements in young alluvium and progressive and continued offset of fluvial terrace deposits along the hft we suggest on this basis and the size and possible synchroneity of displacements recorded in the trenches that there exists the potential for earthquakes larger than recorded in the historical record and with the potential to rupture lengths of the hft greater than the 250 km we have studied

some elements of continental subduction along the himalayan front abstract detachment tectonics in which the subducting basement is not internally affected by thrusting and a steady state system in which the pattern of deformation and topography are invariant uplift is balanced by erosion and the material can experience subsequent phases of deformation by migrating through the system are proposed to be the fundamental mechanisms of convergence at the himalayan arc both surface and subsurface data are more consistent with these concepts than with more familiar concepts widely used in current models intracrustal thrusting and evolutionary tectonics where superimposed phases of deformation are interpreted as distinct phases the belt of intermediate magnitude thrust earthquakes the topographic front at the high himalaya and the main central thrust mct are associated with the same fundamental element the basement thrust front btf which traces a small circle in the central portion of the himalayan arc fault plane solutions indicate thrusting in the radial direction of this arc this radial convergence at the btf implies that tibet is extending laterally at a rate similar to the rate of convergence across the btf this extension cannot be unidirectional and must be parallel to the btf if the circular shape of the btf is invariant

continuous deformation of the tibetan plateau from global positioning system data global positioning system velocities from 553 control points within the tibetan plateau and on its margins show that the present day tectonics in the plateau is best described as deformation of a continuous medium at least when averaged over distances of 100 km deformation occurs throughout the plateau interior by ese wnw extension and slightly slower nne ssw shortening relative to eurasia material within the plateau interior moves roughly eastward with speeds that increase toward the east and then flows southward around the eastern end of the himalaya crustal thickening on the northeast ern and eastern margins of the plateau occurs over a zone 400 km wide and cannot be the result of elastic strain on a single major thrust fault shortening there accommodates much of india s penetration into eurasia a description in terms of movements of rigid blocks with elastic strain associated with slip on faults between them cannot match the velocity field

the active tectonics of the eastern himalayan syntaxis and surrounding regions source parameters of 53 moderate sized earthquakes obtained from the joint inversion of regional and teleseismic distance long period body waves provide the data set for an analysis of the style of deformation and kinematics in the region of the eastern himalayan syntaxis focal mechanisms of eastern himalayan events show oblique thrust consistent with the n ne directed movement of the indian plate as it underthrusts a boundary that strikes at an oblique angle to the direction of convergence earthquakes near the sagaing fault show strike slip mechanisms with right lateral slip earthquakes on its northern splays however indicate predominant thrusting evidence that the dextral motion on the sagaing fault which accommodates a portion of the lateral motion between india and southeast asia terminates in a zone of thrust faulting at the eastern himalayan syntaxis remaining motion between india and southeast asia is accommodated in a zone of distributed shear in east burma and yunnan manifested by strike slip and oblique normal faulting east west extension crustal thinning and clockwise rotation of crustal blocks we determined strain rates throughout the region with a moment tensor summation using 25 years modern and 85 years modern and historic of earthquake data we matched the observed strains with a fifth order polynomial function and from this we determined both the velocity field and rotations with respect to a specified region velocities calculated relative to south china stationary show that the entire area extending from 20 n 36 n within deforming asia yunnan western sichuan and east tibet constitutes a distributed dextral shear zone with clockwise rotations up to 1 7 m y maximum in the region of the eastern syntaxis proper integrated strains across this zone relative to south china stationary show 38 mm yr 12mm yr of north directed motion at the himalaya remaining plate motion relative to south china fixed must be taken up by the underthrusting of india beneath the lesser himalaya strike slip motion on the sagaing fault and intraplate ne directed shortening within ne india as well as ne directed shortening within the eastern syntaxis proper 10 mm yr 2 mm yr of relative right lateral motion between india and southeast asia is absorbed in the region between the sagaing and red river faults 94 e 100 e it is the clockwise vorticity relative to south china associated with the deformation in yunnan east tibet and western sichuan that provides the relative north directed motion of 38 12 mm yr at the himalaya not all of the deformation is accommodated in right lateral shear between india and south china and between east tibet and south china velocity gradients exist that are parallel to the trend of the shear zone relative to a point within western sichuan 32 n 100 e the velocity field shows that the yunnan crust is moving s se at rates of 8 10 mm yr relative to south china there is no eastward expulsion of crustal material beyond the eastern margin of the tibetan plateau

evolution of the himalayan paleogene foreland basin influence of its litho packet on the formation of thrust related domes and windows in the eastern himalayas a review abstract eocene oligocene foreland basin was formed in response to the india asia collision and ensuing himalayan orogenesis the initial collision during late paleocene to early eocene was broadly contemporaneous laterally the paleogene sediments although discontinuously exposed are remarkably similar in their character and organization in the eastern himalayas it is virtually concealed tectonically but is exposed close to and beneath the main boundary thrust mbt as narrow but laterally extensive thrust slivers of fossiliferous eocene sediments lateral continuity and similar marine fauna in them establish the presence of thicker eocene sediments beneath mbt further north several domes and windows in the eastern himalayan frontal belt have evolved with similar geometry the largest siang window exposes duplex antiform of paleogene sediments and volcanics at the core which have arched up the mbt roof thrust the latter underlies passively domed up late plaeozoic and proterozoic himalayan thrust packets the cores of other windows mainly expose low grade proterozoic rocks with or without the late paleozoic rocks a similar sequence of pre tertiary thrust packet is exposed to the south in the frontal belt which override the neogene sediments across mbt a buried basement indenture of the indian continent continues beneath the siang window located at the eastern himalayan syntaxis the cores of other windows are possibly arched up by the duplexes of pre tertiary and tertiary sediments during the process of southward movement of the crystalline and foreland sheets

late cenozoic right lateral strike slip faulting in southern tibet field observations collected during the sino french himalaya tibet cooperation project 1980 1982 show that right lateral faulting between southern and northern tibet roughly along the chord joining the eastern and western syntaxes of the himalayan arc is a major component of the active tectonics north of the himalayas just north of the well developed rifts of southern tibet we studied three right lateral 100 200 km long strike slip faults forming an en echelon array along that chord evidence for earthquake surface breaks was found on each of these faults for the m 8 beng co or damxung strike slip earthquake of november 18 1951 rupture parameters could be constrained to be 8 2 m and l 90 km offset glacial and postglacial morphological markers 105 years and 104 years b p imply displacement rates of the order of 1 2 cm yr on the three faults the en echelon fault zone appears to extend westward 2000 km across the plateau to the karakorum fault and is thus referred to as the karakorum jiali fault zone kjfz fast rates of slip on it and on faults along the northern rim of tibet appear to contrast with the slower rates of deformations in the interior of the plateau our estimates of slip rates on the strike slip and normal faults of southeastern tibet suggest that eastward extrusion of north tibet between the right lateral kjfz and the left lateral altyn tagh and kun lun faults absorbs at least 30 of the present convergence between india and asia we propose an instantaneous velocity model of the active tectonics of asia compatible with such faulting rates and geometries evidence for tertiary right lateral strike slip movements in southern tibet and around the eastern syntaxis of the himalayas is also found in the structural record offsets of various large scale geological features imply that these movements have been large

analysis of drainage basin symmetry as a rapid technique to identify areas of possible quaternary tilt block tectonics an example from the mississippi embayment there is a coincidence of seismicity and major river valleys in the southwestern mississippi embayment that suggests control of the drainage pattern by northwest trending faults pleistocene river terraces reveal a strong southwestward preferred river migration in this region that may be a result of fault block tilting a rapid new technique of drainage basin analysis is herein presented that quantifies transverse topographic basin symmetry these data permit discrimination of random stream migrations and regionally preferred stream migrations and identify the direction of maximum migration if bedrock dip can be shown to be a negligible influence on stream migration then the direction of regionally preferred migration implies a period of ground tilting in that direction drainage basin asymmetry vectors bearing and degree of asymmetry calculated from transverse topographic profiles of 271 4 km basin segments in the study area suggest preferred stream migration in response to west southwest ward ground tilting bearing 259 the eastward regional dip of bed rock horizons only locally influences migration river terrace distributions reveal a chronology of stream migration episodes southwestward migration in the ouachita saline and arkansas river basins occurred during early to middle pleistocene time in the southwestern mississippi embayment a wisconsin early holocene southwestward migration episode is evidenced along southeast flowing reaches of the ouachita and arkansas rivers but not along the southeast flowing reach of the intervening saline river suggesting that these rivers overlie separate northwest trending tilt blocks although this technique does not provide direct evidence of ground tilting it provides a quick look method of identifying possible tilting elements in neotectonic regions using only topographic maps this technique is of greatest utility where active faults are concealed or poorly exposed such as in the mississippi embayment

submarine fan and channel levee deposits in the lower cretaceous bogota trough colombian andes abstract bogota trough in the cordillera oriental of colombia was an elongate ne sw oriented lower cretaceous basin it was one of the main depocentres in the northern andes during earliest cretaceous time six lithofacies and three facies associations are recognised based on four detailed stratigraphic sections situated in the western portion of the trough sedimentation in the basin comprised channel levee fan lobe and outer fan basin plain depositional environments channel levee complexes without a well developed fan growth pattern were more proximal to the sediment supply in more distal settings the migrating channels evolved into suprafan lobes their sediments were covered by outer fan basin plain deposits at a time of retrogradation of the fan system the evolution in the basin continued with progradation and development of depositional lobes and channel fill middle fan environments the western portion of the trough was situated near to the zone of convergence between the nazca and the south american plates and the main sediment supply derived from the paleo central cordillera which in early cretaceous time consisted of an uplifted jurassic plutonic arc this active margin defined the coexistence of small sand rich radial fans and channel levee complexes in the eastern portion of the basin main source area the stable guayana shield determined the existence of a larger fan system of a hybrid type between radial and elongate fans despite the differences between the two fan systems in eastern and western portions of the trough the observed retrogradational and progradational sequences are similar

response of active tectonics on the alluvial baghmati river himalayan foreland basin eastern india active tectonics in a basin plays an important role in controlling a fluvial system through the change in channel slope the baghmati an anabranching foothills fed river system draining the plains of north bihar in eastern india has responded to ongoing tectonic deformation in the basin the relatively flat alluvial plains are traversed by several active subsurface faults which divide the area in four tectonic blocks each tectonic block is characterized by association of fluvial anomalies viz compressed meanders knick point in longitudinal profiles channel incision anomalous sinuosity variations sudden change in river flow direction river flow against the local gradient and distribution of overbank flooding lakes and waterlogged area such fluvial anomalies have been identified on the repetitive satellite images and maps and interpreted through dem and field observations to understand the nature of vertical movements in the area the sub surface faults in the baghmati plains cut across the river channel and also run parallel which have allowed us to observe the effects of longitudinal and lateral tilting manifested in avulsions and morphological changes

himalayan seismic hazard the devastating earthquake in bhuj on 26 january 2001 highlighted the high earthquake risk in the indian region of gujarat in their perspective bilham et al warn that major earthquakes may be expected in another part of india the himalayan arc an analysis of historic earthquakes suggests that several major earthquakes are overdue in this region but that recent low activity has focused attention away from the himalayan arc projections from earlier earthquakes suggest that just one of the possibly overdue himalayan earthquakes may lead to 200 000 predictable fatalities