paleoseismic evidence of a giant medieval earthquake in the eastern himalaya we present here the results of a paleoseismic investigation carried across a 10 m high fault scarp at panijhora village west bengal in northeastern india accelerator mass spectrometer analyzed 14c radiocarbon age constraints from six detrital charcoal samples ranging between 1688 b c and a d 1152 are consistent with the great medieval earthquake of a d 1255 that is interpreted to have produced a minimum observed fault slip of 5 m in the trench exposure recalibration of radiocarbon ages from previous studies at harmutty nameri and marha in the eastern himalaya using bayesian statistical analyses further substantiates the possibility that the a d 1255 earthquake might have ruptured the himalayan front over a length of 800 km from 85 87 to 93 76 e longitudes

structural geology and regional tectonic significance of the ramgarh thrust himalayan fold thrust belt of nepal 1 the ramgarh thrust is one of the major fault systems of the himalayan thrust belt in nepal and northern india the ramgarh thrust sheet is 0 2 2 0 km thick and can be traced along strike the entire length of the himalaya in nepal the fault generally places the oldest paleoproterozoic rocks in the lesser himalayan series upon younger lesser himalayan rocks or lower miocene foreland basin deposits regional balanced cross sections suggest that the ramgarh thrust had at least 120 km of initial south vergent displacement subsequently the frontal part of the thrust experienced further slip as the roof thrust for a large duplex in underlying lesser himalayan rocks ramgarh hanging wall strata are greenschist grade phyllite quartzite and augen gneiss all of which locally exhibit phyllonitic and mylonitic fabrics that indicate a top to the south sense of shear structural fabrics in the ramgarh thrust sheet are generally parallel to the fabrics in rocks above and below the thrust sheet regional and local mapping of the ramgarh thrust in nepal demonstrates that the fault always places a hanging wall flat upon a footwall flat except where local lateral ramps complicate its geometry similarly the structurally overlying main central thrust always places a hanging wall flat in greater himalayan series rocks upon the regionally flat ramgarh thrust sheet these geometric relationships preclude kinematic and thermal models that elevate greater himalayan and lower lesser himalayan rocks along high angle thrust ramps in the vicinity of the present traces of the ramgarh and main central thrust faults instead the corresponding footwall ramps for these thrusts must be located more than 100 km north of the current trace of the main central thrust the present steep dips of the ramgarh and main central thrust sheets can be attributed to tilting during emplacement of structurally lower thrust sheets within a large antiformal duplex that occupies most of the lesser himalayan zone the ramgarh thrust sheet overlaps a bed length of at least 100 km in lower miocene foreland basin deposits indicating that a significant amount of displacement on the thrust must have occurred after 15 ma growth of the lesser himalayan duplex and additional slip on the frontal part of the ramgarh thrust occurred from 12 to 5 ma the presence of a major greenschist grade metasedimentary thrust sheet composed of lesser himalayan rocks directly below the main central thrust suggests that the famous inverted metamorphism in this region is a result of structural inversion similarly the concept of a broad zone of intense shear strain related exclusively to emplacement of the main central thrust sheet is probably invalid in nepal

partitioning of convergence in northwest sub himalaya estimation of late quaternary uplift and convergence rates across the kangra reentrant north india the kangra reentrant constitutes a 80 km wide zone of fold thrust belt made of cenozoic strata of the foreland basin in nw sub himalaya earlier workers estimated the total long term shortening rate of 14 2 mm year by balanced cross section between the main boundary thrust and the himalayan frontal thrust geologically estimated rate is nearly consistent with the gps derived slip rate of 14 1 mm year there are active faults developed within 4 8 km depth of the sub himalayan fold thrust belt of the reentrant dating the strath surfaces of the abandoned fluvial terraces and fans above the thrust faults the uplift bedrock incision rates are computed the dips of thrust faults are measured in field and from available seismic depth profiles from the acquired data late quaternary shortening rates on the jawalamukhi thrust jt the soan thrust st and the himalayan frontal thrust hft are estimated the shortening rates on the jt are 3 5 4 2 mm year over a period 32 30 ka the st yields a shortening rate of 3 0 mm year for 29 ka the corresponding shortening and slip rates estimated on the hft are 6 0 and 6 9 mm year during a period 42 ka on the back thrust of janauri anticline the shortening and slip rates are 2 0 and 2 2 mm year respectively for the same period the results constrained the shortening to be distributed largely across a 50 km wide zone between the jt and the hft the emergence of surface rupture of a great and mega earthquakes recorded on the reactivated hft implies 100 km width of the rupture the ruptures of large earthquakes like the 1905 kangra and 2005 kashmir remained restricted to the hinterland the present study indicates that the high magnitude earthquakes can occur between the locking line and the active thrusts

shallow sub surface stratigraphy of the ganga basin himalayan foreland present status and future perspectives the ganga basin in northern india is one of the world s largest fluvial basins and has attracted enormous attention from earth scientists across the globe with a view to understanding large river processes and landforms despite the scarcity of hydrological data from the ganga basin some important studies have been carried out in the last several decades however the unavailability of deep sections in this vast alluvial tract has always limited understanding of the sub surface stratigraphy of these plains during the last decade some important developments have taken place in integrating exposed cliff section data with the drill cores in pre defined transects and with targeted geophysical investigations additionally new areas of the basin have been studied for understanding landscape evolution including the effects of active tectonics this special issue of quaternary international highlights some of these developments from the stratigraphic archives of this large basin this collection of papers covers a wide gamut of subjects including terrace development in the frontal parts of the ganga basin resistivity based mapping of sub surface stratigraphy micromorphology of soils from plains drill core samples historical scale avulsion of large dynamic system such as the kosi active tectonics and landform development in southern ganga plains and finally some policy issues for management of dynamic river systems this introductory paper provides a background and present status of research in the ganga basin it attempts to summarise some of the recent research developments in the ganga basin research and highlights the unresolved issues some of which have been addressed through the contributions in this special issue

primary surface ruptures of the great himalayan earthquakes in 1934 and 1255 it is unclear where plate boundary thrusts generate giant rather than great earthquakes along the himalayas the source sizes and recurrence times of large seismic events are particularly uncertain since no surface signatures were found for those that shook the range in the twentieth century here we challenge the consensus that these events remained blind and did not rupture the surface we use geomorphological mapping of fluvial deposits palaeo seismological logging of river cut cliffs and trench walls and modelling of calibrated 14c ages to show that the mw 8 2 bihar nepal earthquake on 15 january 1934 did break the surface traces of the rupture are clear along at least 150 km of the main frontal thrust fault in nepal between 85 50 and 87 20 e furthermore we date collapse wedges in the sir valley and find that the 7 june ad 1255 earthquake an event that devastated kathmandu and mortally wounded the nepalese king abhaya malla also ruptured the surface along this stretch of the mega thrust thus in the past 1 000 years two great earthquakes 679 years apart rather than one giant eleventh century ad event contributed to the frontal uplift of young river terraces in eastern nepal the rare surface expression of these earthquakes implies that surface ruptures of other reputedly blind great himalayan events might exist the recurrence times of great himalayan earthquakes are difficult to assess because they rarely rupture the surface field mapping and 14c dating of offset fluvial deposits are used to identify two great himalayan quakes that ruptured the surface along the main plate boundary fault in ad 1255 and 1934

paleoseismic evidence from trench investigation along hajipur fault himalayan frontal thrust nw himalaya implications of the faulting pattern on landscape evolution and seismic hazard abstract the study area falls within the mesoseismal zone of 1905 kangra earthquake mw 7 8 two parallel nnw sse striking active fault scarps named as hajipur faults hf1 and hf2 along the northwestern end of the janauri anticline in the foothill zone have displaced floodplain sediments of the beas river the hf1 and hf2 represent the imbricate faults of the himalayan frontal thrust hft and are the result of lateral propagation of deformation from two fold segments i e jf1 and jf2 respectively in northwest direction along the strike ground penetrating radar gpr profiles and trenching across the hf2 reveal two low angle thrust fault strands f1 and f2 displacements of 7 5 m on f2 and 1 5 m on the associated branching faults f a f b and f c were observed total four stratigraphic units unit a gravel with a lens of medium sand unit a is the oldest overlain by units b medium to coarse sand unit c with fine to medium sand and unit d fine to medium sand with scattered gravel were observed in trench radiocarbon ages of the charcoal samples from unit b and unit d optical ages of sediments from units a b and c gpr data and trench log suggest two major events along f1 and f2 strands event i along f1 occurred during 2600 800 yr bp and event ii along f2 around 400 yr bp and before 300 yr bp given the uncertainty in dates it is suggested that the latest event occurred during 1500 1600 ad considering the oldest unit unit a exposed in trench with vertical displacement of 7 5 8 m age of 2600 500 yr bp and net displacement of 9 m during single event along low angle fault 25 implies slip rate 7 6 1 7 mm yr uplift rate 3 2 0 6 mm yr shortening rate 6 9 1 4 mm yr and recurrence interval 1160 250 yr for large magnitude event with mw 7 0 with the recurrence of 1100 yr the penultimate event probably occurred at around 1400 1500 yr bp given the recent gps based slip rate of 14 1 mm yr in kangra reentrant baneerjee and burgman 2002 the present study suggests that about half of this slip is consumed along the hft and that this fault is more active compared to those in the hinterland

timing of late quaternary glaciations in the himalayas of northern pakistan optically stimulated luminescence dating of late quaternary glaciogenic sediments was undertaken in critical areas of the himalayas of northern pakistan in order to examine the timing of glaciation the dates demonstrate that several glaciations occurred during the last glacial cycle in swat the grabral 2 stade and the kalam i stade were dated at ca 77 ka and ca 38 ka respectively the error on the former date is large and it is conceivable that the moraines may have formed during the early part of oxygen isotope stage 3 rather than during oxygen isotope stage 4 the kalam i stade however clearly represents a glaciation during oxygen isotope stage 3 the oldest moraines and those at the lowest altitude in the indus valley at shatial have an age of ca 60 ka these also relate to a major glacial advance during oxygen isotope stage 3 a younger series of moraines the jalipur tillite and glaciofluvial sands at liachar in the indus valley and moraines at rampur tarshing have ages of ca 27 ka ca 21 23 ka and ca 15 ka respectively these dates show that glaciers also occupied parts of the indus valley during oxygen isotope stage 2 these dates and the morphostratigraphy show that glaciation in the pakistani himalaya was more extensive during the early part of the last glacial cycle and that the local last glacial maximum in pakistan was asynchronous with the maximum extent of northern hemisphere ice sheets copyright 2000 john wiley sons ltd

multiple migmatite events and cooling from granulite facies metamorphism within the famatina arc margin of northwest argentina the famatina margin records an orogenic cycle of convergence metamorphism magmatism and extension related to the accretion of the allochthonous precordillera terrane new structural petrologic and geochronologic data from the loma de las chacras region demonstrate two distinct episodes of lower crustal migmatization the first event preserves a counterclockwise pressure temperature path in kyanite k feldspar pelitic migmatites that resulted in lower crustal migmatization via muscovite dehydration melting at 12 kbar and 868 c at 461 1 7 ma the shape of the pressure temperature path and timing of metamorphism are similar to those of regional midcrustal granulites and suggest pervasive ordovician migmatization throughout the famatina margin one dimensional thermal modeling coupled with regional isotopic data suggests ordovician melts remained at temperatures above their solidus for 20 30 ma following peak granulite facies metamorphism throughout a time period marked by regional oblique convergence the onset of synconvergent extension occurred only after regional migmatites cooled beneath their solidus and was synchronous with the cessation of precordillera terrane accretion at 436 ma the second migmatite event was regionally localized and occurred at 700 c and 12 kbar between 411 and 407 ma via vapor saturated melting of muscovite migmatization was synchronous with extension exhumation and strike slip deformation that likely resulted from a change in the plate boundary configuration related to the convergence and collision of the chilenia terrane

great earthquake surface ruptures along backthrust of the janauri anticline nw himalaya abstract results of a paleoseismic trenching investigation on a backthrust in the northern margin of janauri hill at mehandpur 31 18 11 37 n 76 18 31 47 e sub himalayan range of the himachal himalaya are presented the active backthrust revealed the last event took place after 0 8 0 03 ka ago i e post ce 1200 the age of the last earthquake with a minimum fault slip 1 m along f1 fault and presence of single colluvium on the back thrust nearly matches with an earthquake event previously documented on the bhatpur forethrust of the himalayan frontal thrust system uplifted and truncated fluvial terraces due to displacement on the backthrust are preserved along several north flowing river valley sections in the northern limb of janauri anticline the long term vertical uplift rate calculated through dividing difference between current elevation and elevation of current river grade is 1 08 0 08 mm yr field evidence shows fore and backthrusts are active and they form simultaneously but displacements are episodic suggesting the backthrust develops either due to locking of forethrust or to accommodate a large amount of fault slip due to magnitude of earthquake event along the forethrust further the backthrust may be used as an indirect method of inferring the age of the last event that took place along the forethrust

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

effects of internal structure and local stresses on fracture propagation deflection and arrest in fault zones the way that faults transport crustal fluids is important in many fields of earth sciences such as petroleum geology geothermal research volcanology seismology and hydrogeology for understanding the permeability evolution and maintenance in a fault zone its internal structure and associated local stresses and mechanical properties must be known this follows because the permeability is primarily related to fracture propagation and their linking up into interconnected clusters in the fault zone here we show that a fault zone can be regarded as an elastic inclusion with mechanical properties that differ from those of the host rock as a consequence the fault zone modifies the associated regional stress field and develops its own local stress field which normally differs significantly both as regard magnitude and orientation of the principal stresses from the regional field the local stress field together with fault rock heterogeneities and interfaces discontinuities fractures contacts determine fracture propagation deflection along discontinuities interfaces and arrest in the fault zone and thereby its permeability development we provide new data on the internal structure of fault zones in particular the fracture frequency in the damage zone as a function of distance from the fault core new numerical models show that the local stress field inside a fault zone modelled as an inclusion differ significantly from those of the host rock both as regards the magnitude and the directions of the principal stresses also when the mechanical layering of the damage zone due to variation in its fracture frequency is considered the numerical models show abrupt changes in local stresses not only between the core and the damage zone but also within the damage zone itself abrupt changes in local stresses within the fault zone generate barriers to fracture propagation and contribute to fracture deflection and or arrest also analytical solutions of the effects of material toughness the critical energy release rate of layers and their interfaces show that propagating fractures commonly become deflected into and often arrested at the interfaces generally fractures propagating from a compliant soft layer towards a stiffer one tend to become deflected and arrested at the contact between the layers whereas fractures propagating from a stiff layer towards a softer one tend to penetrate the contact thus it is normally easier for fractures to propagate from the host rock into the damage zone than vice versa similarly it is easier for fractures to propagate from the outer stiffer parts of the damage zone to the inner softer parts and from the stiff host rock to the outer damage zone than in the opposite directions these conclusions contribute to increased understanding as to how fractures propagate and become arrested within fault zones and how the fault zone thickness is confined at any particular time during its evolution

seismicity patterns in the himalayan plate boundary and identification of the areas of high seismic potential abstract space time distribution of earthquakes along the himalayan plate boundary has been investigated with a view to discerning fluctuations in seismicity rates associated with great earthquakes the possibilities of epicentre migration and gaps in seismic activity data from 1800 to 1976 were considered this study shows that all great earthquakes m 8 0 were preceded by seismically quiescent periods of at least 19 years furthermore earthquake quiescence has also been recognised to follow the great earthquakes three possible trends of migration of epicentres of great earthquakes have been recognised 1 1 the first trend starts from the 1905 kangra earthquake the epicentres of subsequent earthquakes migrating eastwards along the plate boundary 2 2 the second trend of migration starts from the great nepal earthquake of 1833 associated with eastward migration 3 3 the third trend commences from the great assam earthquake of 1897 and shows a westward migration of earthquake epicentres the middle section of the himalayan convergent plate boundary 80 e to 90 e in general displays a relatively low level of seismicity as compared to the adjacent sections a remarkable decrease in seismicity following the year 1970 has been observed along a section of the himalaya which lies to the east of the rupture zone of the great 1905 kangra earthquake since 1970 the seismicity rate has also dropped in the region lying in between the rupture zones of the great assam earthquakes of 1897 and 1950 as has earlier been reported by khattri and wyss 1978 such decreases in the level of seismicity along active plate boundaries have been demonstrated to be indicative of building up of stresses leading to future great earthquakes mogi 1969 mccann et al 1979

late pleistocene and holocene large magnitude earthquakes along himalayan frontal thrust in the central seismic gap in nw himalaya kala amb india abstract the himalayan frontal thrust hft forms the southernmost active tectonic mountain front of the himalaya to understand the ongoing tectonics further paleoseismological study has been carried out in the vicinity of the hft system along the himalayan front near kala amb india the trench excavation survey conducted across an explicit surface exposure of the hft exhibits two distinct faults considered to be associated with the reactivation of the hft where the middle siwalik rocks late miocene have repeatedly thrust over the late pleistocene and holocene sediments presence of large sized coseismically induced sand injection feature and its disposition recognized in the trench also suggest occurrence of large magnitude earthquakes in this region an uplifted and upwarped strath terrace 3 to 5 m thick alluvium resting over the 15 m high middle siwaliks abruptly truncated by the hft indicates its latest activity optically stimulated luminescence dating techniques were employed to constrain the chronology of events the long term slip rate of the abandoned terraces due to the activity of the hft is estimated to be 3 4 mm yr or greater since late holocene the paleoseismological investigations have provided unambiguous evidences of at least two large magnitude earthquakes occurred in this region where an earthquake with 12 m or larger surface displacement and magnitude 7 5 or greater hit this region in the period between 29 3 ka and 17 ka in the late pleistocene and another great earthquake recurred with 20 22 m or more surface displacement and magnitude of 7 7 or greater between 5 8 ka and 2 ka in the holocene the present study is the first time report of multiple large magnitude paleoearthquakes in the northwestern part of the frontal himalaya during late pleistocene and holocene the repeated reactivation of hft substantiates high seismic potential of the frontal himalaya and calls for more extensive study of paleoearthquakes of this vastly populous mountainous region

bed by bed fold growth by kink band migration sant llorenc de morunys eastern pyrenees ahstract rowth strata deposited over and against the flank of the sant llorenc de morunys fold during its final stages of deformation have been mapped at high resolution as the basis for unraveling the kinematics of fold growth we use restoration techniques based on normal balancing assumptions to decipher the detailed kinematic history of folding the progressive restorations as well as balanced forward modeling show that the last few hundred meters of fold growth were dominated by kink band migration of a sort that is typical of much faultrelated folding the kink band migration has produced complex anticlinal hinge zone geometry including segmented fold hinges linked by disconformities and unconformities which has direct and detailed explanation in terms of fluctuations in deposition rate relative to curved hinge kink band migration rate large fluctuations in the convolution of non steady sedimentation and deformation are demonstrated although the absolute fluctuations in deformation and sedimentation are unknown at a length scale of 100 m kink band migration with little or no deposition is interspersed with sedimentation with little or no deformation at the length scale of 500 m deposition ranges from 200 to 50 of uplift 0 1997 elsevier science ltd all rights reserved

active deformation of the pacific northwest continental margin tilted and uplifted marine terraces in southern oregon show progressive landward tilting of the coastal ranges at about 5 16 10 8 rad yr 1 for the last 0 25 m y tide gauges in washington and british columbia and ten resurveyed leveling lines running inland from the coast indicate contemporary landward down to the east tilt rates of about 1 12 10 8 rad yr 1 averaged over periods of from 10 to 50 years the leveling lines traverse and the terraces cut across dipping cenozoic strata pleistocene dips to 3 mio pliocene dips to 30 and eocene dips to 60 southern oregon from cape blanco to the siletz river shows geodetic or terrace tilting in the same direction as the underlying stratal dips hence present day deformation continues past deformation of the coastal ranges and is most likely related to active subduction of the juan de fuca plate the steep stratal dips lack of major active faults and historic earthquakes and presence of very young bedding plane faults suggest that much of the onshore deformation and shortening within the overlying north american plate is taken up by folding rather than thrust faulting present shortening rates across north trending folds near the coast are between 0 02 and 1 9 10 7 yr 1 the rate of shortening decreases rapidly eastwards from the juan de fuca north american plate boundary a total of about 25 mm yr 1 of permanent shortening could be occurring within the north american plate most of it in the westernmost 40 km the landward tilt and shortening rates are similar to those above many other subduction zones that have experienced great thrust earthquakes while a high strain rate measured near seattle washington has been interpreted as elastic strain accumulation before a thrust earthquake the low level of historic seismicity and the similarity of short and long term deformation rates suggest alternatively that the subduction beneath washington is aseismic the issue has considerable implications for seismic hazard evaluation in the pacific northwest and could be resolved by a search for the effects or lack of effects of prehistoric great earthquakes

control of detachment geometry on lateral variations in exhumation rates in the himalaya insights from low temperature thermochronology and numerical modeling 1 the himalayan range is commonly presented as largely laterally uniform from west to east however geological structures topography precipitation rate convergence rates and low temperature thermochronological ages all vary significantly along strike here we focus on the interpretation of thermochronological data sets in terms of along strike variations in geometry and kinematics of the main crustal detachment underlying the himalaya the main himalayan thrust mht we report new apatite fission track aft ages collected along north south transects in western and eastern central nepal at the latitudes of the annapurna and langtang massifs respectively aft ages are consistently young 3 ma along both n s transects in the high relief zone of the higher himalaya and increase 4 to 6 ma toward the south in the lesser himalaya we compare our new data to published low temperature thermochronological data sets for nepal and the bhutan himalaya we use the full data set to perform both forward and inverse thermal kinematic modeling with a modified version of the pecube code in order to constrain potential along strike variations in the kinematics of the himalayan range our results show that lateral variations in the geometry of the mht in particular the presence or absence of a major crustal scale ramp strongly control the kinematics and exhumation history of the orogen

convergence rate across the nepal himalaya and interseismic coupling on the main himalayan thrust implications for seismic hazard we document geodetic strain across the nepal himalaya using gps times series from 30 stations in nepal and southern tibet in addition to previously published campaign gps points and leveling data and determine the pattern of interseismic coupling on the main himalayan thrust fault mht the noise on the daily gps positions is modeled as a combination of white and colored noise in order to infer secular velocities at the stations with consistent uncertainties we then locate the pole of rotation of the indian plate in the itrf 2005 reference frame at longitude 1 34 3 31 latitude 51 4 0 3 with an angular velocity of 0 5029 0 0072 myr the pattern of coupling on the mht is computed on a fault dipping 10 to the north and whose strike roughly follows the arcuate shape of the himalaya the model indicates that the mht is locked from the surface to a distance of approximately 100 km down dip corresponding to a depth of 15 to 20 km in map view the transition zone between the locked portion of the mht and the portion which is creeping at the long term slip rate seems to be at the most a few tens of kilometers wide and coincides with the belt of midcrustal microseismicity underneath the himalaya according to a previous study based on thermokinematic modeling of thermochronological and thermobarometric data this transition seems to happen in a zone where the temperature reaches 350 c the convergence between india and south tibet proceeds at a rate of 17 8 0 5 mm yr in central and eastern nepal and 20 5 1 mm yr in western nepal the moment deficit due to locking of the mht in the interseismic period accrues at a rate of 6 6 0 4 10 19 nm yr on the mht underneath nepal for comparison the moment released by the seismicity over the past 500 years including 14 m w 7 earthquakes with moment magnitudes up to 8 5 amounts to only 0 9 10 19 nm yr indicating a large deficit of seismic slip over that period or very infrequent large slow slip events no large slow slip event has been observed however over the 20 years covered by geodetic measurements in the nepal himalaya we discuss the magnitude and return period of m 8 earthquakes required to balance the long term slip budget on the mht

active fault fault growth and segment linkage along the janauri anticline frontal foreland fold nw himalaya india the 100 km long frontal foreland fold the janauri anticline in nw himalayan foothills represents a single segment formed due to inter linking of the southern js1 and the northern js2 janauri segments this anticline is a product of the fault related fold growth that facilitated lateral propagation by acquiring more length and linkage of smaller segments giving rise to a single large segment the linked portion marked by flat uplifted surface in the central portion represents the paleo water gap of the sutlej river this area is comparatively more active in terms of tectonic activity well justified by the occurrence of fault scarps along the forelimb and backlimb of the anticline occurrence of active fault scarps on either side of the anticline suggests that the slip accommodated in the frontal part is partitioned between the main frontal thrust i e the himalayan frontal thrust hft and associated back thrust the uplift in the piedmont zone along southern portion of janauri anticline marked by dissected younger hill range suggests fore landward propagation of tectonic activity along newly developed frontal piedmont thrust fpt an imbricated emergent thrust branching out from the hft system we suggests that this happened because the southern segment js1 does not linked up with the northwestern end of chandigarh anticline segment cs in the northwestern end of the janauri anticline due to no structural asperity the tectonic activity on hft was taken up by two hf1 in the frontal part and hf2 towards the hinterland side newly developed parallel active faults hajipur fault branched from the main js2 segment the lateral propagation and movements along hf1 and hf2 resulted in uplift of the floodplain as well as responsible for the northward shift of the beas river gpr and trench investigations suggest that earthquakes during the recent past were accompanied with surface rupture osl optical stimulated luminescence dates from the trench suggests occurrence of at least two events during the recent historic past with the latest event ii during 1500 ad

earthquake faulting as a structural process abstract structural geology is concerned with the history of movement in the earth s crust and the processes by which displacements occur in the upper one third to one half of deforming continental crust displacement is accommodated largely by seismic slip increments on existing faults it follows that earthquakes and related processes are an integral part of structural geology traditionally structural geologists have been preoccupied with the complexity of the finite deformation within fault zones and with the stress states prevailing at the initiation of faults in intact crust future structural work should be directed more towards understanding the dynamic character of fault reactivation during incremental slip and related effects questions of interest include rheological and geometrical controls on the initiation perturbation and termination of ruptures directivity effects associated with rupture propagation the recognition of structures resulting from repeated stress cycling within seismogenic crust and identification of structural features diagnostic of shear stress levels during faulting structures arising from the inter relationships between slip episodes and induced fluid flow are of special importance because these dynamic fault processes appear influential in the development of much fault hosted mineralization mesothermal gold quartz lodes hosted in high angle reverse shear zones of mixed brittle ductile character form illustrative examples of structures that arguably can only be interpreted by seismo structural analysis embodying the concepts listed above

erratic shortening from balanced cross sections of the western himalayan foreland basin causes and implications for basin evolution abstract balanced cross sections from the western himalayan foreland foothill belt reveal a variation in shortening amounts from 22 to 71 3 over a lateral distance of 85 km the large variation may be attributed to the fact that the method of cross section balancing considers the initial layering as horizontal which is an unlikely situation in foreland basins simple trigonometric relationships are used to minimize the error in shortening estimates however the suggested corrections could not be applied to the himalayan foreland basin because of unavailability of the required data on initial basin geometry the study also indicates that shortening rates for the area based on these shortening amounts cannot be used for earthquake prediction

extent and spatial distribution of pleistocene glaciations in eastern tibet as a contribution to the controversial discussion regarding the nature and extent of the pleistocene glaciation on the tibetan plateau additional observations and results were obtained during several chinese german joint expeditions in the investigation area of the eastern and central tibetan plateau it will be shown that the maximum extent of the last glaciation was limited to the glaciation of isolated mountain groups or smaller plateau glaciations these glaciations are characterized by glacial erosional features such as u shaped valleys in the inner mountain massifs and cirques in the higher summit areas accumulation forms such as terminal and lateral moraines less common than basal moraines are marked by granitic and basaltic erratics using two examples from the eastern margin of the tibetan plateau nianbaoyeze shan and northern chola shan the extent of pleistocene glaciations can be mapped by the distribution of terminal and lateral moraines and erratic granite boulders on the slopes of the surrounding schists two to three main pleistocene glaciations can be separated using weathering criteria paleosols and the overlying stratum on the moraines and associated terrace sequences overlying stratum consist of aeolian sandy silt or solifluction debris the younger moraines are found to be characterized by large erratics were therefore named big boulder moraine and can be found over the investigated area the ice free areas are characterized by pleistocene terraces along the main rivers loess deposits with sand and ice wedges at higher elevations e g the basin of zoige and paleosols in the basins below 3500 m a s l e g aba basin or garze basin the hypothesis of an extensive plateau glaciation could not be verified for this region a rising snowline equilibrium line altitudes elas is revealed in two cross sections during the last glacial maximum lgm at the eastern and northern margin of the tibetan plateau snowlines migrated from about 4000 m in the east minshan to 4300 m in the nianbaoyeze and to about 4700 m in the west bayan har shan a rise was also recorded from about 3800 m in the north central qilian shan up to a range of 4300 4950 m different exposures in the kunlun shan to approximately 5200 m in the tanggula shan in the center of the tibetan plateau the general increase of modern and lgm snowlines or elas towards the plateau corresponds with a decrease of precipitation from east to west and from north to south respectively precipitation was more pronounced at the eastern margin during glacial times than compared to present

mesoscale strike slip faults and damage zones at marsalforn gozo island malta well exposed strike slip faults in limestones in the north western part of gozo show damage zones that can be grouped into three categories based on their location along faults tip damage linking damage and distributed damage the predominant fracture types within damage zones include extension fractures and secondary faults tip damage zones usually show wedge shaped patterns formed by antithetic faults and extension fractures commonly accompanied by block rotation several fractures are combined at linking damage zones typically with the concentration of a high intensity of fractures structures in distributed damage zones are typically similar to the classical riedel shear pattern evolutionary and 3d models are proposed in terms of the geometries of damage zones for small displacement strike slip fault zones different evolutionary routes depend on fault tip modes and locations

geometry and kinematics of main frontal thrust related fault propagation folding in the mohand range northwest himalaya abstract the main frontal thrust mft shapes the 2500 km long frontal himalayan arc between two syntaxes surprisingly the structural geometry and kinematics of the mft sheet remains poorly constrained along portions of this arc even though it is a major seismogenic plate boundary hazard that affects 53 million people living in the himalaya and roughly 600 million living in the combined himalayan drainage basin apollo 2017 here we integrate methods to constrain and quantify mft deformation and its associated topographic growth in the mohand range at the northwestern himalayan front we use a new structural data and trishear modeling to detail the mft related structural geometry across a portion of the range and confirm it to be a fault propagation fold with an exposed monocline in the hanging wall as previously hypothesized srivastava et al 2016 and b microstructural finite strain and grain size analysis from 11 transport parallel thin section samples of middle siwalik sandstones to propose that the fold formed by near surface 1 5 km frictional sliding and block supported cataclastic flow new luminescence dating of fault gouge and uplifted sand bodies indicate that mft activity is older 105 ka in the central compared to the western 15 ka mohand range implying that recent mft motion has been variable and segmented we next present boundary element method based dislocation modeling results along 3 transects to confirm that the along strike topographic growth is variable but consistent with the existing data and our interpretations balanced cross sections indicate that a maximum of 23 26 km2 area was eroded from the mohand range since folding began modern era estimates of minimum erosion from our dislocation modeling compared to existing topographic profiles suggest that 1 km2 erosion occurred in the range our integrated approach helps us to better constrain resolve reported inconsistencies and advance our understanding of mft related deformation topographic growth and erosion within the dehradun recess and across its outboard range front himalayan arc segmentation into salients and recesses likely impacts along strike earthquake rupture propagation thus it is important to understand how each segment behaves evolves and perhaps interrelates as part of a larger perspective towards evaluating active collisional wedge fronts and their potential seismic hazards

chronology and rates of faulting of ventura river terraces california new evidence concerning the chronology of four late pleistocene terraces of the ventura river near oak view california that are vertically offset and tilted by reverse and reverse flexural slip faults provides a means of estimating rates of fault movement and downcutting by the ventura river radiocarbon ages of charcoal contained within terrace deposits date two of the terraces correlation of soils that have developed on terrace deposits and extrapolation of the rate of vertical displacement of the arroyo parida santa ana fault not a flexural slip fault date the others resulting age estimates for the four main late pleistocene terraces are qt5b 30 000 qt6a 38 000 qt6b 54 000 and qt6c 92 000 yr b p vertical slip rates on flexural slip faults range from 0 3 to 1 1 mm yr and apparently are related to the rate form and mechanics of folding of the north limb of the ayers creek canada larga syncline average rates of downcutting of the ventura river for several intervals during the late pleistocene estimated from the chronology and relative elevation of river terraces north of the arroyo panda santa ana fault upstream from the zone of faulting vary from 0 5 to 1 3 mm yr the range in rates probably reflects variations in local uplift as well as adjustments to changing eustatic sea level climatic conditions and or regional deformation of the western transverse ranges the average rate of downcutting of the ventura river north of the zone of flexural slip faulting is 0 8 mm yr compared with 1 2 to 2 2 mm yr in the deformation zone immediately to the south this apparently indicates that during tectonic deformation there is an approximate balance between the rate of uplift due to faulting and folding and the rate of downcutting by the fluvial system

lateral moraines of glacier de tsidjiore nouve form development and implications the relationship between supraglacial lateral moraines and lateral dump moraines at arolla switzerland is discussed a detailed study of the lateral moraines of glacier de tsidjiore nouve reveals their complex form as superimposed and nested ridges and the current mode of development possibly related to the passage of a kinematic wave sedimentological analysis indicates that much of the constituent debris is of supraglacial origin it is transported either directly from the base of slopes flanking the pigne d arolla ice fall or via englacial septa comprising marginal sediment incorporated in the accumulation zone a calculation of the volume of debris in the lateral moraines suggests that glacier de tsidjiore nouve has recently been more active in transporting and depositing supraglacial debris than in glacial erosion sensu stricto

structural evolution of the frontal fold thrust belt nw himalayas from sequential restoration of balanced cross sections and its hydrocarbon potential abstract two sedimentary lithotectonic zones are traditionally recognized in the northwestern himalayan frontal fold thrust belt in the nahan salient the lesser himalaya zone lhz and the sub himalaya zone shz the lhz is made up of a sequence of proterozoic to early cambrian rocks and the shz is made up of cenozoic rock sequences which were deposited subsequent to the india asia collision serial balanced cross sections show that the structural geometries become increasingly complex from independent ramp anticlines near the foreland through imbricate fan duplex to stacked up horses towards the hinterland sequential restoration suggests a structural evolution in which a foreland propagating in sequence thrusting event was followed by out of sequence thrusting in an approximately break back style during the out of sequence movement some of the ramps formed during in sequence thrusting were repeatedly reactivated leading to very complex structural geometries particularly in the lhz in such a complexly deformed terrain a rigorous structural modelling approach combined with a robust geochemical and geochronological database should be used to carry out calibrated petroleum system modelling and thus reduce exploration risk

structure and shortening of the kangra and dehra dun reentrants sub himalaya india surface geology oil well seismic reflection and magnetostratigraphic data are integrated to evaluate the structural style and the shortening rate at the himalayan front sub himalaya of northwest india the sub himalaya between the main boundary thrust and the himalayan frontal fault is the primary surface expression of shortening between the himalaya and the indian plate at certain locations the himalayan frontal fault is a blind thrust beneath anticlines of siwalik tertiary molasse parallel to the himalayan orogen the main boundary thrust is sinuous so the width of the sub himalaya ranges from 30 to 80 km where the sub himalaya is narrow nahan salient tertiary rocks are exposed in imbricate thrust sheets where the sub himalaya is broad kangra and dehra dun reentrants alluvium fills wide synclinal valleys duns seismic reflection data reveal that surface anticlines form in association with south vergent thrusts that root in a decollement at the base of the tertiary section reflection profiles and well data also indicate that the basement lithology changes northward from precambrian crystalline rocks beneath the indo gangetic plains to precambrian and cambrian metasedimentary rocks beneath the sub himalaya the sub himalayan decollement dips 2 5 northward beneath the kangra reentrant but it is steeper 6 beneath the dehra dun reentrant the kangra and dehra dun reentrants display fault propagation folds having steep limbs in the north and fault propagation and fault bend folds that have gently north dipping limbs in the south a balanced cross section of the kangra reentrant shows that a minimum of 23 km shortening has occurred since 1 9 1 5 ma yielding a shortening rate of 14 2 mm yr shortening has occurred at a rate of 6 16 mm yr across the dehra dun reentrant these data are similar to other published shortening rates and indicate that approximately 25 of the total india eurasia convergence at this longitude is accommodated within the sub himalaya given continued convergence and the presence of overpressured wells in the kangra reentrant the region is likely at risk from moderate and or great earthquakes in the future

distribution of the late quaternary deformation in northwestern himalaya abstract three main cenozoic thrusts at the front of northwestern himalaya have accommodated most of the india eurasia convergence across the belt over the last million years and produced the present relief their recent tectonic activity is poorly known because of the long period of inaccessibility of the jammu and kashmir state and because the latest and only large earthquake recorded in the region occurred in 1555 ad we show where the deformation is localized during the late quaternary and determine shortening rates across the structures by analyzing the geometry and chronology of geomorphic markers the main boundary thrust in this region ceased moving at least 30 ka ago on the contrary the more external medlicott wadia thrust and main frontal thrust both merging at depth on the sub flat detachment of the main himalayan thrust exhibit hectometric scale deformations accumulated during the last thousands of years the total shortening rate absorbed by these faults over the last 14 24 ka is between 13 2 and 27 2 mm yr 11 2 3 8 and 9 0 3 2 mm yr respectively part of this deformation may be associated to the geometry of the chenab reentrant which could generate an extra oblique component however the lower bound of our shortening rates is consistent with previously determined geodetic rates active deformation on these structures follows an in sequence out of sequence pattern with breaking of both ramps being possible for earthquakes triggered on the main detachment

oblique convergence and slip partitioning in the nw himalaya implications from gps measurements we report gps measurements of crustal deformation across the kashmir himalaya we combined these results with the published results of gps measurements from the karakoram fault system and suggest that in the kashmir himalaya the motion between the southern tibet and india plate is oblique with respect to the structural trend we estimated this almost north south oblique motion to be 17 2 mm yr which is partitioned between dextral motion of 5 2 mm yr on the karakoram fault system and oblique motion of 13 6 1 mm yr with an azimuth of n198 e in the northwest southeast trending kashmir himalayan frontal arc thus the partitioning of the india southern tibet oblique motion is partial in the kashmir himalayan frontal arc however in the neighboring nepal himalaya there is no partitioning the entire india southern tibet motion of 19 20 mm yr is arc normal and is accommodated entirely in the himalayan frontal arc the convergence rate in the kashmir frontal himalaya is about 25 less than that in the nepal himalayan region however here the karakoram fault system accommodates about 20 of the southern tibet and indian plate convergence and marks the northern extent of the nw himalayan arc sliver the kaurik chango rift a north south oriented seismically active cross wedge transtensional fault appears to divide the sliver in two parts causing varying translatory motion on the karakoram fault on either side of the kaurik chango rift

india eurasia collision chronology has implications for crustal shortening and driving mechanism of plates the motion of the indian plate is determined in an absolute frame of reference and compared with the position of the southern margin of eurasia deduced from palaeomagnetic data in tibet the 2 600 900 km of continental crust shortening observed is shown to have occurred in three different episodes subduction of continental crust intracontinental thrusting and internal deformation and lateral extrusion the detailed chronology of the collision and plate reorganizations in the indian and pacific oceans supports the hypothesis that slab pull is a dominant driving mechanism of plate tectonics

convergence across the northwest himalaya from gps measurements 1 horizontal velocities of 26 global positioning system gps stations in the northwest himalayan region provide new constraints on the partitioning of india eurasia convergence and elastic strain accumulation about the locked main frontal thrust mft the northwest striking karakorum fault slips at 11 4 mm yr and contributes to east west extension of southern tibet and westward motion of the northwest himalaya towards nanga parbat rather than playing a role in eastward extrusion of tibet crustal shortening across the himalaya occurs within a zone centered about 100 km north of the siwalik foothills and the mft model inversions of the gps data indicate that the mft is locked over a width of 100 km comparison with geologic mft slip rate estimates suggests that this zone is building up a slip deficit at a rate of 14 1 mm yr and will eventually fail in future great earthquakes

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

earthquake slip estimation from the scarp geometry of himalayan frontal thrust western himalaya implications for seismic hazard assessment geometric and kinematic analyses of minor thrusts and folds which record earthquakes between 1200 ad and 1700 ad were performed for two trench sites rampur ghanda and ramnagar located across the himalayan frontal thrust hft in the western indian himalaya the present study aims to re evaluate the slip estimate of these two trench sites by establishing a link between scarp geometry displacements observed very close to the surface and slip at deeper levels as geometry of the active thrust beneath the scarp is unknown we develop a parametric study to understand the origin of the scarp surface and to estimate the influence of ramp dip the shortening estimates of rampur ghanda trench by line length budget and distance displacement d d method show values of 23 and 10 15 respectively the estimate inferred from the later method is less than the line length budget suggesting a small internal deformation ramnagar trench shows 12 shortening by line length budget and 10 25 by the d d method suggesting a large internal deformation a parametric study at the trenched fault zone of rampur ghanda shows a slip of 16 m beneath the trailing edge of the scarp and it is sufficient to raise a 8 m high scarp this implies that the rampur ghanda scarp is balanced with a single event with 7 8 m coseismic slip in the trenched fault zone at the toe of the scarp 8 15 mean deformation within the scarp and 16 m slip at depth along a 30 ramp for a pre 1400 earthquake event a 16 m slip is the most robust estimate of the maximum slip for a single event reported previously by trench studies along the hft in the western indian himalaya that occurred between 1200 ad and 1700 ad however the ramnagar trenched fault zone shows a slip of 23 m which is larger than both line length and d d methods it implies that a 13 m high scarp and 23 m slip beneath the rigid block may be ascribed to multiple events it is for the first time we report that in the south eastern extent of the western indian himalaya ramnagar scarp consists of minimum two events i pre 1400 ad and ii unknown old events of different lateral extents with overlapping ruptures if the more optimistic two seismic events scenario is followed the rupture length would be at least 260 km and would lead to an earthquake greater than mw 8 5

evidence for a great medieval earthquake 1100 a d in the central himalayas nepal the himalayan orogen has produced three thrust earthquakes with moment magnitude m w 7 8 to 8 5 during the past century yet no surface ruptures associated with these great earthquakes have been documented here we present paleoseismic evidence from east central nepal that since 700 a d a single earthquake ruptured the frontal thrust fault at 1100 a d with a surface displacement of 17 5 3 meters and a lateral extent and size that could have exceeded 240 kilometers and m w 8 8 respectively ruptures associated with m w

record of glacier variations during the last glacial in the turkestan range of the pamir alay kyrgyz republic moraines in five valleys of the turkestan range of the pamir alay kyrgyz republic were analyzed based on their geographical position and elevation morphology and ecological characteristics the moraines represent four glacial advances turkestan stage i during the last glacial stage ii during the late holocene stage iii during the little ice age ad 1400 1900 and stage iv during the 20th century in turkestan stage i the glaciers expanded to about 5 10 km from their present termini during marine isotope stage mis 2 radiocarbon ages for several soil layers buried in a lateral moraine of the asan usin glacier frontal area indicate that glaciers shrank or stagnated between at least 48 and 42 kyr bp during the warm climate of mid mis 3 these findings suggest that the glacier expansion in mid mis 3 was relatively small compared to the glacier expansion of mis 2 during the last glacial

a new kinematic evolutionary model for the growth of a duplex an example from the rangit duplex sikkim himalaya india abstract the lesser himalayan duplex lhd is a prominent structure through much of the lesser himalayan fold thrust belt in the darjeeling sikkim himalaya a component of the lhd is exposed in the rangit window as the rangit duplex rd the rd consists of ten horses of the upper lesser himalayan sequence gondwana buxa upper daling the duplex varies from hinterland dipping in the north through an antiformal stack in the middle to foreland dipping in the south the ramgarh thrust rt is the roof thrust and based on a balanced cross section the main himalayan sole thrust is the floor thrust at a depth of 10 km and with a dip of 3 5 n retrodeformation suggests that the rd initiated as a foreland dipping duplex with the early ramgarh thrust as the roof thrust and the rt as the floor thrust the rt became the roof thrust during continued duplexing by a combination of footwall imbrication and concurrent rt reactivation this kinematic history best explains the large translation of the overlying mct sheets the restoration suggests that rd shortening is 125 km and the original gondwana basin extended 142 km northward of its present northernmost exposures within the window

quaternary rate of folding of the ventura avenue anticline western transverse ranges southern california upper quaternary terraces of the ventura river california are uplifted tilted and folded over the ventura avenue anticline rates of uplift and tilting have decreased since inception of the structure over the past 200 ka assuming that the chronology based on amino acid racemization 14c dates and soils correlation is approximately correct then the minimum possible average rate of uplift in the axial region of the fold has decreased from 14 mm yr to 2 mm yr during the past 200 ka interval rates of uplift for the periods 200 ka to 80 or 105 ka 80 or 105 ka to 30 ka and 30 ka to present are respectively about 20 mm yr 9 mm yr and 5 mm yr the rate of tilting shows a similar trend decreasing from 5 8 urad yr 2 5 urad yr and 1 2 urad yr for the same time intervals respectively based on the mechanics of flexural slip folds in stratified sedimentary rocks these data suggest that the rootless ventura avenue anticline is a fold that has been shortening at a relatively constant rate of about 9 mm yr since its inception

integrated analysis of structures and landforms of an intermontane longitudinal valley pinjaur dun and its associated mountain fronts in the nw himalaya abstract frontal regions of the himalaya associated with topographic recesses are commonly marked by the development of intermontane valleys locally referred to as duns the relationship between structural evolution and landform development of an intermontane longitudinal valley pinjaur dun is explored to understand the role of tectonic processes on landform development the pinjaur dun has a length of 180 km it is divisible into a wider 20 km northwestern and a narrower 6 8 km southeastern segment the barsar thrust the nalagarh thrust and the himalayan frontal thrust form the mountain fronts in the area the proposed structural model integrates the transverse structures for e g ghaggar tear fault with the sequential development of imbricates in front of the main boundary thrust the pinjaur dun formed as a consequence of the fold thrust related uplift that formed the outermost siwalik hills most of the geomorphic units formed within the dun are the result of interactions between the imbricates such as the pinjaur thrust jhajara thrust and pinjaur garden fault these interactions also resulted in the development of a significant and prominent drainage divide between the jhajjara and the sirsa rivers of the pinjaur dun landform development and landscape evolution in this frontal region of the himalaya are a consequence of the interaction of thrust fold and transverse fault zone tectonics and constitute a record of transient 102

growth linkage and termination processes of a 10 km long strike slip fault in jointed granite the gemini fault zone sierra nevada california abstract field based structural analysis of an exhumed 10 km long strike slip fault zone elucidates processes of growth linkage and termination along moderately sized strike slip fault zones in granitic rocks the gemini fault zone is a 9 3 km long left lateral fault system that was active at depths of 8 11 km within the transpressive late cretaceous sierran magmatic arc the fault zone cuts four granitic plutons and is composed of three steeply dipping northeast and southwest striking noncoplanar segments that nucleated and grew along preexisting cooling joints the fault core is bounded by subparallel fault planes that separate highly fractured epidote chlorite and quartz breccias from undeformed protolith the slip profile along the gemini fault zone shows that the fault zone consists of three 2 3 km long segments separated by two zones of local slip minima slip is highest 131 m on the western third of the fault zone and tapers to zero at the eastern termination slip vectors plunge shallowly west southwest and show significant variability along strike and across segment boundaries four types of microstructures reflect compositional changes in protolith along strike and show that deformation was concentrated on narrow slip surfaces at or below greenschist facies conditions taken together we interpret the fault zone to be a segmented linked fault zone in which geometrical complexities of the faults and compositional variations of protolith and fault rock resulted in nonuniform slip orientations complex fault segment interactions and asymmetric slip distance profiles

redefining medlicott wadia s main boundary fault from jhelum to yamuna an active fault strand of the main boundary thrust in northwest himalaya abstract the mbt demarcates a tectonic boundary between the tertiary sub himalaya and the pre tertiary lesser himalaya south of the mbt another tectonically important fault extends from muzaffarabad and riasi in jammu kashmir to bilaspur and nahan in himachal medlicott and wadia had designated this fault the main boundary fault mbf in simla hills and jammu region respectively in between these two areas later workers gave local area names to the mbf as the riasi thrust in jammu palampur thrust in kangra bilaspur thrust in simla hills and nahan thrust in sirmur we have reviewed and established the tectonostratigraphic framework and physical continuity of the lower tertiary belt and the mbf the lower tertiary belt lying south of the mbt has characteristic tectonostratigraphic setting with discontinuous bodies of stromatolite bearing proterozoic limestone overlain with depositional contact by the paleocene lower part middle eocene marine subathu patala formation which in turn overlain by the upper oligocene lower miocene non marine dharamsala murree formation to avoid confusion with the mbt we designate collectively the mbf and related faults as the medlicott wadia thrust mwt the mwt extends east of hazara kashmir syntaxis to river yamuna covering a distance of 700 km further east of yamuna the lower tertiary belt pinches out and the mwt merges with the sensuo stricto mbt the proterozoic limestone represents the basement over which the lower tertiary sediments were deposited the limestone basement with its cover was detached by the mwt exhuming to the surface and thrusting over largely the siwalik group the reactivated balakot bagh fault causative fault for the 2005 kashmir earthquake extends southeast with right step to the riasi thrust the riasi thrust shows evidence of reactivation and active tectonic activity in jammu region it extends further east to the palampur thrust in kangra reentrant which lies within the 1905 kangra earthquake rupture zone the bilaspur thrust continuation of the palampur thrust shows active faulting south of simla hills between sataun and yamuna river these observations indicate that the mwt represents a southern strand of the sensuo stricto mbt and shows active faulting in some segments

paleoseismological evidence of surface faulting along the northeastern himalayan front india timing size and spatial extent of great earthquakes the similar to 2500 km long himalayan arc has experienced three large to great earthquakes of m w 7 8 to 8 4 during the past century but none produced surface rupture paleoseismic studies have been conducted during the last decade to begin understanding the timing size rupture extent return period and mechanics of the faulting associated with the occurrence of large surface rupturing earthquakes along the similar to 2500 km long himalayan frontal thrust hft system of india and nepal the previous studies have been limited to about nine sites along the western two thirds of the hft extending through northwest india and along the southern border of nepal we present here the results of paleoseismic investigations at three additional sites further to the northeast along the hft within the indian states of west bengal and assam the three sites reside between the meizoseismal areas of the 1934 bihar nepal and 1950 assam earthquakes the two westernmost of the sites near the village of chalsa and near the nameri tiger preserve show that offsets during the last surface rupture event were at minimum of about 14 m and 12 m respectively limits on the ages of surface rupture at chalsa site a and nameri site b though broad allow the possibility that the two sites record the same great historical rupture reported in nepal around a d 1100 the correlation between the two sites is supported by the observation that the large displacements as recorded at chalsa and nameri would most likely be associated with rupture lengths of hundreds of kilometers or more and are on the same order as reported for a surface rupture earthquake reported in nepal around a d 1100 assuming the offsets observed at chalsa and nameri occurred synchronously with reported offsets in nepal the rupture length of the event would approach 700 to 800 km the easternmost site is located within harmutty tea estate site c at the edges of the 1950 assam earthquake meizoseismal area here the most recent event offset is relatively much smaller 2 5 m and radiocarbon dating shows it to have occurred after a d 1100 after about a d 1270 the location of the site near the edge of the meizoseismal region of the 1950 assam earthquake and the relatively lesser offset allows speculation that the displacement records the 1950 m w 8 4 assam earthquake scatter in radiocarbon ages on detrital charcoal has not resulted in a firm bracket on the timing of events observed in the trenches nonetheless the observations collected here when taken together suggest that the largest of thrust earthquakes along the himalayan arc have rupture lengths and displacements of similar scale to the largest that have occurred historically along the world s subduction zones

paleoseismic evidence of a major earthquake event s along the hinterland faults pinjore garden fault pgf and jhajra fault jf in northwest himalaya india abstract despite identification of numerous active faults in hinterland of the himalaya most of the paleoseismological studies are confined to the frontal fault himalayan frontal thrust hft barring few examples no attempt has been made to understand the spatial and temporal pattern of earthquakes occurred along the hinterland faults in this article we present new data on the coseismic slip and timing of the latest faulting event along the two hinterland faults the pinjore garden fault pgf and jhajra fault jf in northwest himalaya trench investigations suggest at least two earthquakes along pgf and jf with the most recent event mre subsequent to 1283 ce 1443 ce and preceded 1600 ce and around 1223 ce 1442 ce respectively with observed single event and multi event slip of 4 26 m and 12 7 m on pgf the timing of the latest event deduced from the previous trenches hajipur to rampur ganda indicates striking coherence with those along the hinterland faults pgf and jf we propose that the hinterland faults might have been reactivated by an independent earthquake event between 1283 ce and 1600 ce just like the 1905 kangra 2005 kashmir 2015 nepal earthquakes which failed to rupture the front but produced surface deformation along the hinterland faults the loading of the un ruptured not defined portion of mht with the residual stress along with constant convergence between the plates during the medieval period must have facilitated another earthquake rupturing the frontal thrust within 100 300 years of time frame our results support the evidence that northwest himalaya must have hosted multiple large magnitude earthquakes between 1200 ce 1600 ce but seismic quiescence now raises an alarm to the society and the government for the earthquake preparedness

microfracture analysis of fault growth and wear processes punchbowl fault san andreas system california abstract fabric and timing relations of mode i microfractures are used to test current hypotheses for the origin of damage along large displacement faults by the processes of fault growth and wear oriented samples 0 075 m to 1 km from the punchbowl fault surface i e ultracataclasite layer document an increase in development of preferred orientation and increase in density of microfractures towards the ultracataclasite layer defining a zone of fault related microfracture damage about 100 m thick a distinct microfracture set that is perpendicular to the slip direction of the fault is present throughout the damage zone this implies that the average orientation of the maximum principal compressive stress within the damage zone was nearly normal to the fault surface two additional microfracture sets are present one oriented at low angles to the fault within meters of the ultracataclasite layer and another low angle set that occurs in the outermost damage zone the preferred orientations and timing relations are most consistent with local damage accumulation from stress cycling associated with slip on a geometrically irregular relatively weak fault surface low angle microfractures nearest the ultracataclasite layer also may record wear associated with the passage of earthquake ruptures and those in the outermost damage zone may be consistent with andersonian fault formation and subsequent fault weakening

timing and style of late quaternary glaciation in the eastern hindu kush chitral northern pakistan a review and revision of the glacial chronology based on new optically stimulated luminescence dating abstract glacial landforms and sediments provide evidence for two late quaternary major glaciations in the eastern hindu kush new optically stimulated luminescence osl dating was undertaken to define the timing of these glaciations and associated sediment deposition the drosh glacial was defined by osl dating to have occurred during marine isotopic stage 3 producing an extensive valley glaciation that extended to an altitude of 1300 m above sea level asl in the main valley with an equilibrium line altitude ela depression of 1200 m the pret glacial produced a valley glaciation that extended to an altitude of 1670 m asl in the main valley with an ela depression of 1000 m the new osl dating suggests that this glacial stage probably represents several glacial advances that occurred during the latter part of the last glacial moraines representing two minor glacial advances the shandur and barum glacial stages were also recognized near the contemporary glaciers these probably formed during the middle late holocene and little ice age respectively this study and comparisons with adjacent regions suggest that there was limited glaciation during the global last glacial maximum lgm in the hindu kush deglaciation in the mountain ranges of the himalayas and the consequent meltwater discharge into the adjacent seas was negligible immediately after the global lgm and it was therefore of minor importance as a forcing factor for global climate change during the end of the last glacial cycle however our studies show that glaciation and particularly deglaciation is important in controlling the deposition of thick valley fills and the landscape evolution of the high mountain environments

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

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

geological and geomorphic evidences of neotectonic activity along the himalayan frontal thrust nahan salient nw himalaya india abstract in this paper we report geomorphic signatures of neotectonic activity identified from the area around nahan salient along himalayan frontal thrust hft using remote sensing and field investigations we document two newly discovered exposures of hft fault zone and active fault traces along the mountain front at khetpurali nahan salient nw himalaya india we demonstrate that hft fault zone at khetpurali is not blind instead it is exposed at the surface along with highly deformed folded strata in the hanging wall and its geometry is quite variable with the possibility of along strike segmentation the geometry of fold and various deformational features preserved in the hanging wall indicate a process of fault propagation fold this is in contrast to the previous observation of fault bent folding within the nahan salient two three levels of river terraces are preserved and truncated in the hanging wall along with the active fault scarps which are linked to uplift along hft fault zone the khetpurali anticline ka is a fault propagating fold formed due to displacement and shortening along hft which dips 30 towards north and strike wnw ese the uplift u along the ka is calculated to be 73 m and accommodated 7 3 shortening of the original length before the fault tip truncated the fold various deformational structures have been identified within the hanging wall around tip damage zone of 80 m perpendicular to hft fault zone and in the core of ka northwest of khetpurali a south facing hogback structure 100 m high is formed due to erosion of forelimb of the anticline at khetpurali tectonic control due to folding of strata and uplift of river terraces is evident as the dudhgarh river forms v shaped profile near the thrust compared to the wide floodplain before and after crossing the hft fault zone along strike segmentation of hft and associated anticlines is observed as the surface trace of hft is offset at khetpurali trilokpur and sabilpur due to the strike slip faults the study reveals that hft has been truncated by tear faults and has different subsurface geometries in study area which may have implication on seismic hazard in the nahan salient where three thrusts himalayan frrontal thrust hft nahan thrust nt and main boundary fault mbf are located at relatively shorter distance of 6 km as compared to the surrounding recesses

a complex thrust sequence in western himalaya the active medlicott wadia thrust the recent activity of the medlicott wadia thrust mwt is investigated by geomorphic and tectonic studies in the riasi zone south of the pir panjal range india jammu kasmir state of western himalaya in the riasi area the mwt forms a splay of five faults that dip northward the recent activity of the splay is quantified using a set of deformed quaternary alluvial units the central branch of the thrust splay moved precambrian limestones above quaternary sediments and is sealed by 36 3 ka youngest osl age deposits the other branches offset the top of a 15 1 ka youngest osl age alluvial fan by 180 to 120 m the two southernmost branches form 17 34 m high non cylindrical scarps and the two northernmost branches also offset the fan by 8 m and 54 m respectively a balanced cross section parallel to the n210 e thrust motion suggests that the sequence of activity is complex an in sequence propagation is found for the three southern tea scorpion and rain faults and an out of sequence reactivation for the northern pillar fault furthermore several thrusts simultaneously activated for intervals of a few thousand years whereas others are episodically inactive nearly 10 mm yr of india eurasia convergence is regularly absorbed by the mwt a value greater than the one estimated for the western segment of the mwt affected by the 2005 kashmir earthquake where the thrust tectonics interacts with the complex kinematics of the syntax this work indicates that the mwt is very active and might be related to thick skinned tectonics in the western himalaya

spatial variability in microscopic deformation and composition of the punchbowl fault southern california implications for mechanisms fluid rock interaction and fault morphology abstract we examine the distribution and nature of microstructures geochemistry and mineralogy along two traverses across the punchbowl fault southern california to determine the morphology and deformation mechanisms of the fault zone in schistose rocks the punchbowl fault is an exhumed fault that has two main strands of slip localization and has a total of 44 km of right slip protolith in the study area consists of the pelona schist which is primarily a quartz albite muscovite actinolite schist with thin to medium banding and rare metabasalts the traverses are 1 3 km apart and were conducted at a site with a single fault strand and a site where both principal strands of the fault are exposed the fault zone thickness is a function of the type of measurement that is used to define it for the single strand site analysis of the distribution of microfractures shows that the fault zone consists of a roughly 40 m thick damaged zone adjacent to the fault core the damaged zone is marked by an increase in veins thin cataclasite bands inter and intragranular fracturing and alteration relative to the country rock brittle grain size reduction occurs in a zone 10 m thick as measured from the fault core which consists of a continuous 10 cm thick very fine grained cataclasite that experienced repeated alteration vein injection and grain size reduction whole rock geochemical analyses of the fault related rocks suggest that the geochemically defined fault zone is less than 10 m thick volume loss at the site with one fault strand appears to have been small the dominant alteration reactions associated with the fault core are the hydration of hornblende and actinolite accompanied by the alteration of muscovite to produce a quartz chlorite albite epidote ultracataclasite the composition of the fault core is variable and locally influenced by one of the adjacent protoliths the examination of the two fault strand sites shows that two damaged zone fault core structures are present the region between the two strands experienced a greater degree of deformation than the protolith but the total deformation is much less than immediately adjacent to the fault cores the total thickness of the damaged zone around the two strands is less than 200 m the fault core enveloped by a damaged zone morphology as well as the textures of the fault core rocks are similar to rocks associated with the north branch san gabriel fault which formed in crystalline rocks with a total displacement of 22 km fault thickness is less in the pelona schist than in the crystalline rocks perhaps owing to more efficient strain localization in the schists thus the faults of the san andreas system may be thinner in regions where schists or franciscan rocks are the protolith but the main fault core may be a constant feature of the fault zone transformation induced weakening is less important in this part of the punchbowl fault since the protolith has a large amount of mica the structure of the fault zone with two principal slip surfaces is marked by both chemical changes and microstructures and indicates that some parts of the san andreas fault system may consist of multiple slip surfaces each with a damaged zone that together may create a fault zone 100 m thick and in which slip is localized to zones meters to decimeters thick

drainage conformation and transient response of river system in thrust segmentation of northwest himachal himalaya india abstract in the northwest himalayan region the ongoing out of sequence deformation caused emergence of back thrust bt around 43ka which attributed the growth of anticlines parallel to the strike of major thrusts this spatial and temporal geomorphic deformation is accompanied by coexisting river incision in the axial zone of anticlines and base level fall along with upstream migration of knickpoints in the longitudinal river course we used the stream power incision model spim which relates the normalized steepness index ksn and concavity index ref with the slope s of longitudinal river profile as a power law function of upstream area a and estimated these parameters for beas soan and sutlej rivers to decipher the spatial distribution of deformation pattern using srtm dem and based on strike parallel variations of the ksn we identified segmented nature of the nw himalayan thrusts further the dynamics of river basins and transience along the tributaries and main stem rivers has been analyzed by chi analysis which is attributed to geometric disequilibrium of the rivers the results of ksn and analysis together suggests that the crustal shortening of nw himalaya is caused by segmental reactivation of the thrusts further investigating the change in steepness along longitudinal course aids in understanding the differential uplifts patterns in actively deforming segments of major nw himalayan thrusts

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

late holocene variation of the raigorodskogo glacier and climate change in the pamir alai central asia during the late holocene the raigorodskogo glacier in the pamir alai central asia expanded before 3215 after 1545 and at 310 cal years bp as dated by the 14c calibrated ages of wood samples from moraine deposits and terrace exposures the glacier expansions which were accompanied by increased melt water run off over the terrace surface were confined to the proglacial area the terrace deposits with intercalated buried soil layers provide evidence of two obvious warm periods when the glacier abruptly retreated during the late holocene shortly before 1545 cal years bp and again sometime before ca 500 cal years bp fallen juniperus turkestanica broken by moraine deposits suggests that the largest glacial expansion during the little ice age occurred 310 cal years bp the glacier expansion in the little ice age was on roughly the same scale as that which occurred in the cold period after 1545 cal years bp observational records of the glacier terminus and moraine positions indicate that recent glacier advances occurred in the years 1908 1911 sometime in 1911 1934 and in 1960 1977 these advances were small while the glacier recessions were larger in the 1900s with large recessions also sometime in 1911 1934 and in 1977 1998 the glacier recession rate of 27 m year in 1911 1934 was faster than the rates of 13 m year in 1977 1990 and 21 m year in 1990 1998 however the glacier recession rate has been accelerating recently particularly after 1990 this recession reflects recent climate warming in inland asia

contemporary tectonics of the himalayan frontal fault system folds blind thrusts and the 1905 kangra earthquake the sub himalayan fold thrust belt consists of deformed late cenozoic and older deposits south of the main boundary thrust mbt in pakistan east of the indus river the sub himalaya comprises the potwar plateau and the salt range which is thrust southward over the jhelum river floodplain along the salt range thrust although an estimated 9 14 mm a 1 shortening has been taken up on the salt range thrust during the last 2 ma the range front scarp does not show signs of recent faulting shortening may be shifting southward to the lilla overpressured anticline which rises from the jhelum floodplain as a fault propagation fold farther east shortening is partitioned among several anticlines underlain by foreland and hinterland dipping blind thrusts southeast of the main deformation zone the pabbi hills overpressured anticline is best explained as a fault propagation fold throughout the potwar plateau and salt range thrusts and folds rise from a basal decollement horizon in eocambrian evaporites the pakistani part of the decollement horizon could generate large earthquakes only if these evaporites die out northward at seismogenic depths in india and nepal the sub himalaya is narrower reflecting the absence of evaporites and a steeper slope of the basement towards the hinterland the southern boundary of the sub himalaya is the himalayan front fault discontinuous because part of the shortening is expressed at the surface by folding broad alluvial synclinal valleys dun valleys are bounded on the south by rising barrier anticlines of siwalik molasse the 1905 kangra earthquake m8 produced uplift on the mohand anticline and the dehra dun valley suggesting that this earthquake occurred on a decollement horizon above basement downdip from the fold if so the kangra event is the largest known earthquake on a blind thrust expressed at the surface as a fold

active fault and paleoseismic studies in kangra valley evidence of surface rupture of a great himalayan 1905 kangra earthquake mw 7 8 northwest himalaya india our findings suggest that interseismic strain accumulated south of the fault ramp under the higher himalayas was not only released periodically along the himalayan frontal thrust hft during large magnitude earthquakes but also along the active faults in the hinterland the 4 april 1905 kangra earthquake m w 7 8 killed more than 20 000 people and destroyed the towns of kangra and dharamsala in northwest himalaya in spite of its large magnitude with a maximum intensity x on the rossi forel intensity scale recorded in the epicentral area no surface rupture was reported and no focal mechanism is available this article uses satellite imagery and field mapping to identify an active right lateral strike slip fault named the kangra valley fault kvf we infer that the kvf represents the surface rupture of the 1905 kangra earthquake extending west northwest east southeast and east west for 60 km it cuts through the kangra and sihunta valleys and is capable of producing m w 7 2 earthquakes existence of the kvf in the kangra re entrant is indicative of oblique convergence and slip partitioning between the main boundary thrust in the north the jawalamukhi thrust in the south and a strike slip fault in the northwest himalaya paleoseismic investigations revealed evidence of at least four earthquakes on the kvf event i oldest occurred before 900 b c or between 900 b c and 2500 b c event ii occurred between 100 b c and 80 b c penultimate event iii occurred around a d 800 and a d 1000 and the most recent event event iv occurred after a d 1620 and before a d 1940 and is likely the 1905 kangra earthquake m w 7 8 a longer recurrence along the kvf is inferred between older paleoearthquake events i and ii and a shorter interval of 1050 150 years is inferred between younger events ii iii and iv because the strain during the 1905 kangra earthquake was released along the kvf potential for large magnitude earthquakes in northwest himalaya along the hft still remains online material figures of quartz response curves growth curves and histograms of sample numbers and trench photomosaics

timing of india asia collision geological biostratigraphic and palaeomagnetic constraints 1 a range of ages have been proposed for the timing of india asia collision the range to some extent reflects different definitions of collision and methods used to date it in this paper we discuss three approaches that have been used to constrain the time of collision the time of cessation of marine facies the time of the first arrival of asian detritus on the indian plate and the determination of the relative positions of india and asia through time in the qumiba sedimentary section located south of the yarlung tsangpo suture in tibet a previous work has dated marine facies at middle to late eocene by far the youngest marine sediments recorded in the region by contrast our biostratigraphic data indicate the youngest marine facies preserved at this locality are 50 6 52 8 ma in broad agreement with the timing of cessation of marine facies elsewhere throughout the region double dating of detrital zircons from this formation by u pb and fission track methods indicates an asian contribution to the rocks thus documenting the time of arrival of asian material onto the indian plate at this time and hence constraining the time of india asia collision our reconstruction of the positions of india and asia by using a compilation of published palaeomagnetic data indicates initial contact between the continents in the early eocene we conclude the paper with a discussion on the viability of a recent assertion that collision between india and asia could not have occurred prior to 35 ma

a balanced cross section across the himalayan frontal fold thrust belt subathu area himachal pradesh india thrust sequence structural evolution and shortening abstract the structural evolution of the frontal fold thrust belt in the nw himalayas has been deciphered through the construction of a balanced cross section which incorporates all the tertiary and the precambrian sedimentary rock units belonging to the sub himalaya zone and the lesser himalaya zone respectively towards the foreland the structural geometry is rather simple with widely spaced thrust ramps and simple fault bend folds in the hangingwall in the central sector the structural geometry seen at the surface is essentially controlled by a thrust system that can be approximately described as a buried hinterland dipping duplex the structural geometry becomes extremely complex in the northeastern sector i e towards the hinterland owing to out of sequence thrusting low ramp spacing leading to dislocation of older thrusts and related structures by younger thrusts folded thrusts and breached horses stacked up horses occupied by lesser himalaya zone formations dominate the structural geometry in this sector an in sequence thrusting event followed by out of sequence thrusting in an approximately break back style best describe the structural evolution of the fold thrust belt in this area a total slip of about 96 km occurred along the detachment and the shortening partitioned within the fold thrust belt is about 72 km or about 71

late quaternary holocene evolution of dun structure and the himalayan frontal fault zone of the garhwal sub himalaya nw india abstract dun structures are common in the sub himalayan zone of the himalaya bounded by the main boundary thrust mbt and the himalayan frontal thrust hft they are broad synclinal longitudinal valleys formed as a consequence of the exhumation of the range front of the himalaya in the garhwal sub himalaya these structures have grown since 0 5 ma with the peak activity postdating 100 ka a series of out of sequence deformation structures have been identified within the mbt hft bounded dun structures they are identified on the basis of geomorphic post 100 ka stratigraphic and structural expressions with activity as young as the early holocene to the south of the range front of the himalaya uplift has been observed in the piedmont zone with peculiar active tectonic geomorphic expressions piedmont sediments of 15 5 ka determined by optically simulated luminescence osl have been affected by the above uplift the complete tectonic scenario has been analyzed and an attempt has been made to delineate the sequential evolution of these structures during the post 100 ka period late quaternary holocene in the himalayan range front

earthquake recurrence and rupture dynamics of himalayan frontal thrust india the black mango fault is a structural discontinuity that transforms motion between two segments of the active himalayan frontal thrust hft in northwestern india the black mango fault displays evidence of two large surface rupture earthquakes during the past 650 years subsequent to 1294 a d and 1423 a d and possibly another rupture at about 260 a d displacement during the last two earthquakes was at minimum 4 6 meters and 2 4 to 4 0 meters respectively and possibly larger for the 260 a d event abandoned terraces of the adjacent markanda river record uplift due to slip on the underlying hft of 4 8 0 9 millimeters per year or greater since the mid holocene the uplift rate is equivalent to rates of fault slip and crustal shortening of 9 6 3 5 7 0 millimeters per year and 8 4 3 6 7 3 millimeters per year respectively when it is assumed that the hft dips 30 10

estimating the return times of great himalayan earthquakes in eastern nepal evidence from the patu and bardibas strands of the main frontal thrust the return times of large himalayan earthquakes are poorly constrained despite historical devastation of cities along the mountain range definitive links between events and specific segments of the main frontal thrust mft are not established and paleoseismological records have not documented the occurrence of several similar events at the same location in east central nepal however recently discovered primary surface ruptures of that megathrust in the a d 1255 and 1934 earthquakes are associated with flights of tectonically uplifted terraces we present here a refined longer slip history of the mft s two overlapping strands patu and bardibas thrusts in that region based on updated geomorphic neotectonic mapping of active faulting two 1 3 km long shallow seismic profiles and logging of two river cut cliffs three paleoseismological trenches and several pits with constraints from 74 detrital charcoals and 14 cosmogenic nuclide ages the amount of hanging wall uplift on the patu thrust since 3650 450 years requires three more events than the two aforementioned the uplift rate 8 5 1 5mm yr thrust dip 25 5 n and apparent characteristic behavior imply 12 17 5m of slip per event on the bardibas thrust discrete pulses of colluvial deposition resulting from the coseismic growth of a flexural fold scarp suggest the occurrence of six or seven paleo earthquakes in the last 4500 50 years the coeval rupture of both strands during great himalayan earthquakes implies that in eastern nepal the late holocene return times of such earthquakes probably ranged between 750 140 and 870 350 years

gps measurements of present day convergence across the nepal himalaya the high elevations of the himalaya and tibet result from the continuing collision between india and asia which started more than 60 million years ago1 4 from geological and seismic studies of the slip rate of faults in asia5 it is believed that approximately one third of the present day convergence rate between india and asia 58 4mmyr 1 is responsible for the shortening uplift and moderate seismicity of the himalaya great earthquakes also occur infrequently in this region releasing in minutes the elastic strain accumulated near the boundary zone over several centuries and accounting for most of the advance of the himalaya over the plains of india the recurrence time for these great earthquakes is determined by the rate of slip of india beneath tibet which has hitherto been estimated indirectly from global plate motions6 from the slip rates of faults in asia7 8 from seismic productivity9 and from the advance of sediments on the northern ganges plain10 here we report geodetic measurements using the global positioning system gps of the rate of contraction across the himalaya which we find to be 17 52 2 mm yr 1 from the form of the deformation field we estimate the rate of slip of india beneath tibet to be 20 5 2 mmyr 1 strain sufficient to drive one or more great himalayan earthquakes with slip similar to that accompanying the magnitude 8 1 bihar nepal 1934 earthquake may currently be available in western nepal

paleoseismic evidence of the ce 1505 and ce 1803 earthquakes from the foothill zone of the kumaon himalaya along the himalayan frontal thrust hft india abstract the importance of understanding earthquake sources in india and nepal was underscored by the disastrous 2015 earthquakes of 25 april gorkha mw 7 8 and 12 may kodari mw 7 3 aftershock in nepal the kumaon garhwal segment experienced strong earthquakes in ce 1505 and ce 1803 probably along the himalayan frontal thrust hft of these the ce 1505 was the greatest earthquake reported from the region in historical chronicles however no surface ruptures related to either of 1505 or 1803 have been identified from the kumaon garhwal segment and an ambiguity remained about their ruptures dispite recent reports of ce 1505 surface rupture in western nepal we used high resolution satellite cartosat 1 data for mapping active fault traces and carried out paleoseismic studies to identify paleo earthquakes along the hft a trench excavated across the kaladungi fault kf a branching fault of hft revealed evidence of at least three earthquakes event i the oldest occurred between bce 467 and ce 570 event ii occurred between ce 1294 1587 we infer that the event ii was the most likely historically reported great himalayan earthquake of ce 1505 event iii occurred between ce 1750 1932 and may represent the large magnitude ce 1803 7 5 mw

quaternary glaciation of tibet the geological evidence the question of the number and extent of pleistocene glaciations on the qinghai xizang tibet plateau remains contentious there has been considerable research activity in tibet by chinese scientists since the late 1950s and their principal findings including data on glacial and periglacial geomorphology sedimentology tectonics stratigraphy and lake history have been used to reconstruct ice margins and palaeosnowlines three and in places four distinct glaciations have been recognised the most extensive occurring in the later middle pleistocene valley and piedmont glacial systems with some mountain ice caps and a small ice sheet on the upper reaches of the huang he have been recognised but there is no evidence of a single tibetan ice sheet as the plateau and the himalaya karakoram underwent accelerating uplift through the quaternary there occurred progressive desiccation in the interior as the influx of indian ocean moisture was constrained equilibrium line elevations in the last glacial maximum were 4000 m in the south east and northeast plateau margins rising to 5500 m in the northwest interior the heat island provided by the plateau the progressive reduction in precipitation most marked during the glacials and the strong southeast to northwest precipitation gradients produced a glacier distribution pattern dominated by the trans tibetan mountain ranges tectonics and periglacial including aeolian processes have played an equal role with glaciation in generating the plateau s quaternary sedimentary succession

rupture propagation inferred from damage patterns slip distribution and segmentation of the 1957 mw8 1 gobi altay earthquake rupture along the bogd fault mongolia 1 a detailed analysis of the rupture patterns and slip changes along the surface rupture associated with the 1957 gobi altay earthquake mw 8 1 in mongolia which occurred along the bogd left lateral strike slip fault was carried out to better understand segmentation and propagation the major surface ruptures show a simple linear pattern whereas minor ruptures along the major ruptures which are concentrated at rupture step overs and tip zones show complex patterns in the latter case their patterns strongly resemble the geometric and kinematic characteristics of previously reported mesoscale fault damage patterns the geomorphologic offsets show that left lateral slip dominated with an average displacement of 3 5 to 4 0 m but it decreased or transferred to dip slip components mainly at rupture step overs and tip zones abrupt changes of rupture patterns and slip distribution indicate that the coseismic surface rupture along the bogd fault comprises three major segments from west to east namely the north ih east ih and north baga bogd segments and a highly damaged eastern tip zone based on the location of the epicenter as well as the asymmetrically distributed damage structures and slips we infer that the surface rupture propagated eastward unilaterally through several segments and reached the easternmost step over which acted as a tough barrier the rupture finally terminated producing a highly deformed tip damage zone developed to accommodate released stress we argue that detailed analysis of damage patterns slip distribution and slip transfer can help us to better understand fault segmentation and rupture propagation

landscape evolution and deduction of surface deformation in the soan dun nw himalaya india abstract the consequence of strain accumulation along various himalayan thrusts is manifested in shaping the topography and present day lanscape features of the himalaya consequently the strain accomodation is attributed to the occurrence of various devastating earthquakes in the himalayan domain including 1905 kangra earthquake mw 7 8 which occurred along the kangra valley fault in the present study we analyzed and estimatedsss fault related parameters gradient length anomaly gla analysis together with interferometric synthetic aperture radar in sar measurements to understand the landscape evolution and deformation pattern within the soan dun piggy back basin in the northwest himalayan front we combined the results of geodetic geological geomorphology and insar to constrain the uplift and subsidence between himalayan frontal thrust hft and main boundary thrust mbt zones the estimated results of fault parameters reveal that the horizontal shortening of northwest himalaya is higher than the vertical uplift the computed values of gla magnitude analysis for the uplifted region vary from 9 21 to 0 77 whereas these range from 5 48 to 26 60 for the subsided region the depicted range of vertical deformation observed from the insar measurements ranges from 3 13 to 3 14 mm y where the positive and negative value of phases are correlated with the ground uplift and subsidence the rate of deformation observed from persistent scatterer interferometry psi phase velocity and gla magnitude is positively supported by the chronologically constrained uplift rates as 3 4 0 3 mm y the geomorphic evidences such as folded tilted and truncated alluvial fan surfaces offsetting of channels fault scarps and displaced sedimentary sequences indicate active nature of the soan dun the study would be eventually useful for seismic hazard assessment and future infrastructure development in the seismotectonically active regions like soan dun of nw himalayan front

paleoseismic investigation along nalagarh thrust evidence of late pleistocene earthquake in pinjaur dun northwestern sub himalaya abstract the present article is the first time reporting of a paleoearthquake that occurred during late pleistocene time along the nalagarh thrust nt in the pinjaur dun in northwestern sub himalaya using corona satellite photographs multi spectral irs satellite data and aerial photographs a prominent active fault has been identified at nalagarh in pinjaur dun this fault in the alluvial fan is located very close to the nt which borders the topographic front of the tertiary rocks against quaternary deposits a trench excavation survey was carried out at nalagarh for detailed paleoseismic studies across this thrust fault displacing all the lithologic units of the fan sequence the fault plane has an average dip of 30 due ene and a vertical displacement of 1 6 m and slip of 2 5 m along the fault the lithological units consisting of alternating sand and gravel show back tilting and asymmetrical tight folding based on optically stimulated luminescence osl ages the oldest litho unit in the trench is 85 83 7 2 ka and the youngest is 67 05 8 4 ka the osl age of the sample collected from the easterly exposure of the fault shows an age of 20 ka the faulting and associated induced deformation features suggest occurrence of a late pleistocene large magnitude earthquake along nt in the nalagarh region of the pinjaur dun following the deposition of the quaternary sedimentary units the late pleistocene fault substantiates the seismic potential of pinjaur dun and calls for more exhaustive study of paleoearthquakes in this fast developing industrial belt and highly populous mountainous region

active faulting south of the himalayan front establishing a new plate boundary abstract new tectonic uplifts south of the salt range thrust and himalayan front thrust hft represent an outward step of the plate boundary from the principal tectonic displacement zone into the indo gangetic plain in pakistan the lilla anticline deforms fine grained overbank deposits of the jhelum river floodplain 15 km south of the salt range the anticline is overpressured in eocambrian non marine strata in northwest india south of dehra dun the piedmont fault pf lies 15 km south of the hft coalescing fans derived from the himalaya form a piedmont old piedmont zone 15 20 km wide east of the yamuna river this zone is uplifted as much as 15 20 m near the pf and bedding is tilted 5 7 northeast holocene thermoluminescence optically stimulated luminescence dates for sediments in the old piedmont zone suggest that the uplift rate might be as high as several mm a the old piedmont zone is traced northwest 200 km and southeast another 200 km to the nepal border these structures analogous to protothrusts in subduction zones indicate that the himalayan plate boundary is not a single structure but a series of structures across strike including reactivated parts of the main boundary thrust north of the range front the hft sensu stricto and stepout structures on the indo gangetic plain displacement rates on all these structures must be added to determine the local india himalaya convergence rate

contrasting tectonically driven exhumation and incision patterns western versus central nepal himalaya although the himalayan range is classically presented as cylindrical along strike segmentation of the range in terms of structure topography precipitation and erosion patterns is becoming widely recognized the potential climatic or tectonic controls on these lateral variations remain controversial thermokinematic models predict that the geometry of the main himalayan detachment controls the kinematics exhumation and topography of the orogen where the detachment includes a major crustal ramp the topography shows a steep gradient that focuses orographic precipitation and exhumation whereas the topography is gentler and exhumation less focused above a flatter detachment we test this prediction by comparing the patterns of river incision specific stream power and long term exhumation from apatite fission track thermochronology in central nepal where a major crustal ramp has been imaged by geophysical methods with new exploratory data from the remote karnali river transect in western nepal where a ramp is predicted to be absent or minor our results show that both exhumation rates and river incision capacity are significantly higher and focused on the crustal ramp in central nepal whereas they are lower and the pattern is more diffuse in western nepal these differences support a model in which lateral variations in topography and exhumation are controlled by variations in the geometry of the detachment and imply that along strike climatic variations in the himalaya respond to tectonics rather than driving it

sedimentology of plio pleistocene late orogenic deposits associated with intraplate subduction the upper siwalik subgroup of a part of panjab sub himalaya india abstract this study provides a detailed sedimentologic documentation of the lithofacies cyclicity sandbody geometry palaeoflow variability and depositional models of the youngest late orogenic deposits of the siwalik molasse these deposits represent one of the important examples of sedimentation in the zone of intraplate subduction of the himalayan collision belt lithofacies analysis has resulted in the recognition of four conglomerate facies massive matrix supported conglomerate crudely stratified conglomerate trough cross stratified conglomerate planar cross stratified conglomerate five sandstone facies erosional scour and fill pebbly sandstone medium to coarse grained sandstone fine to medium grained ripple drift laminated sandstone bioturbated calcareous fine grained sandstone and six mudstone facies parallel laminated bioturbated mudstone reddish brown massive mudstone variegated mudstone bluish grey to violet mudstone buff coloured mudstone pebbly mudstone in addition hard calcareous layers have been recognised as a separate facies state the deduced cyclic sequences of the tatrot and pinjor formations of the upper siwalik subgroup show fining upward characters from cs coarse sandstone to ms mudstone through fs fine sandstone and ss alternations of sandstone and siltstone the sandbodies of the tatrot and pinjor formations reveal a sheet like geometry and an internal dominance of inter storey scour surfaces the presence of intraformational debris mud drapes reactivation surfaces and a general fining upward of grain size indicates fluctuating hydrodynamic conditions with frequent channel abandonment and re occupation resulting in net vertical aggradation the dominant style of sedimentation both in the channel and overbank facies is through vertical aggradation data on the palaeoflow variability indicates that the upper siwalik subgroup can be subdivided into four and three sediment vector sequences in the khetpurali and ghaggar sections respectively the palaeodrainage pattern in the khetpurali section reveals a major influence of northerly drainage twice in the stratigraphic column the high percentage of overbank deposits in individual cycles the lack of vegetal debris organic poor palaeosol units and abundant syngenetic caco 3 activity warrant comparison with the modern anastomosed deposits described from arid central australia some intervals of the sequences are comparable to the sublinear subparallel drainages with local anastomosis of the modern piedmont zone of the himalaya the higher parts of the stratigraphic column indicate proximal braided stream deposits and finally proximal alluvial fan deposits syntectonic activity has controlled the deposition of the megasequences which are a response to episodicity in the activity of basin margin basin margin or basin margin intrabasin structures the vertical stacking of the siwalik megasequences appears to be episodic in character

paleoseismic evidence of a surface rupture along the northwestern himalayan frontal thrust hft abstract new paleoseismic evidence is presented from the bhatpur n 31 18 16 28 e 76 9 50 00 trench site along the himalayan frontal thrust hft on western margin of the janauri anticline in nw himachal himalaya india the latest surface rupture at this site demonstrates coseismic displacement of at least 9 3 m radiocarbon dating of trench samples indicates that the surface ruptures occurred at a d 1400 1460 after comparison with other trench results along the himalayan front two scenarios are presented of the latest surface rupturing earthquake event in the northwestern indian himalaya 1 a single event surface rupturing for a minimum fault length of 450 km or 2 two events of different lateral extent according to the former scenario the latest surface rupture occurred between a d 1404 and 1422 the latter scenario suggests the latest surface rupture occurred between a d 1404 and a d 1460 in the northwestern extent from kala amb to hajipur with 9 0 m of coseismic displacement over a minimum fault length of 200 km yet another surface rupture event in the southeastern extent from kala amb to ramnagar has occurred between a d 1282 and a d 1422 with displacement ranging from 16 0 m to 26 0 m and a minimum surface rupture length of 230 km on the basis of these observations and historical earthquakes it is suggested that the potential for earthquakes larger than those in the historical records are capable of producing surface rupture lengths greater than the 200 to 230 km or 450 km in the northwestern indian himalayan front

the pinjaur dun intermontane longitudinal valley and associated active mountain fronts nw himalaya tectonic geomorphology and morphotectonic evolution abstract the himalayan orogenic belt formed as a result of collision tectonic processes shows abundant evidence of neotectonic activity active tectonics and the occurrence of historical earthquakes its frontal deformation zone is characterized in some segments by intermontane longitudinal valleys duns such frontal segments of the himalaya are marked by the occurrence of multiple mountain fronts in one such segment of the foothills of the nw himalaya the pinjaur dun is developed and marked by three mountain fronts mf1a and mf1b associated with the southernmost himalayan frontal thrust hft mf2 associated with the sirsa fault and mf3 associated with the barsar thrust along the southern margin of the relatively higher main part of the sub himalaya geomorphic responses to the tectonic activity of these and related structural features have been analyzed through the use of geomorphic indices drainage density stream longitudinal profiles drainage anomalies and hypsometric analysis also fault and fold growth and their expression on landform development was studied using a combination of surface profiles and field observations the values of valley floor width to height ratio v f for valleys associated with mf1 ranged between 0 07 and 0 74 and for valleys associated with mf2 ranged from 1 02 5 12 v f for the four major valleys associated with mf1b ranged from 1 1 1 7 the asymmetry factor for 26 drainage basins related to mf1a indicate these have developed under the influence of a transverse structure these results taken together with those obtained from the hack profiles and sl index values hypsometry drainage density and drainage anomalies suggest that the faults associated with the mountain fronts and related structures are active active tectonics and neotectonic activity have led to the formation of four surfaces in the pinjaur dun in addition an important drainage divide separating the sirsa and jhajara drainage networks also developed in the intermontane valley surface profile analysis helped in deciphering the growth history of the fault bend fold structures of the outermost siwalik hills the effects of tectonic activity on the proximal part of the indo gangetic plains are interpreted from the remarkable river deflections that are aligned linearly over tens of kilometers in a zone about 10 km south of the hft based on these integrated structural and tectonic geomorphological approaches a morphotectonic evolutionary model of the dun has been proposed this model highlights the role of uplift and growth history of the fault bend fold structures of the outermost siwalik hills on i the depositional landforms and drainage development of the pinjaur dun and ii valley development of the outermost siwalik hills importantly this study postulates the formation of an incipient mountain front that is evolving ahead of the hft and the outermost siwalik hills in the indo gangetic plains

recent fold growth and drainage development the janauri and chandigarh anticlines in the siwalik foothills northwest india the active growth of a fault and thrust belt in frontal zones of himalaya is a prominent topographical feature extending 2500 km from assam to pakistan in this paper kinematical analysis of frontal anticlines and spatial mapping of active faults based on geomorphological features such as drainage pattern development fault scarps and uplifted quaternary alluvial fans are presented we analyse the geomorphic and hydrographic expressions of the chandigarh and the janauri active anticlines in the nw india siwaliks to investigate the morphological scenario during the folding process we used spatial imagery geomorphometric parameters extracted from digital elevation models and fieldwork folding between the beas and sutlej rivers gives clear geomorphological evidence of recent fold growth presumably driven by movements of blind thrust faults structural style within the janauri and chandigarh anticlines is highly variable fault propagation folds pop up structures and transfer faults the approach presented here involves analysis of topography and drainage incision of selected landforms to detect growth of active anticlines and transfer faults landforms that indicate active folding above a southwest dipping frontal thrust and a northeast dipping back thrust are described along strike differences in ridge morphology are measured to describe the interaction of river channel patterns with folds and thrust faults and to define history of anticline growth the evolution of the apparently continuous janauri ridge has occurred by the coalescence of independent segments growing towards each other by contrast systematic drainage basin asymmetry shows that the chandigarh anticline ridge has propagated laterally from nw to se

interseismic coupling on the main himalayan thrust we determine the slip rate and pattern of interseismic coupling on the main himalayan thrust along the entire himalayan arc based on a compilation of geodetic interferometric synthetic aperture radar and microseismicity data we show that convergence is perpendicular to the arc and increases eastwards from 13 3 1 7 mm yr to 21 2 2 0 mm yr these rates are comparable to geological and geomorphic estimates indicating an essentially elastic geodetic surface strain the interseismic uplift rate predicted from the coupling model closely mimics the topography suggesting that a small percentage of the interseismic strain is permanent we find that the fault is fully locked along its complete length over about 100 km width we don t find any resolvable aseismic barrier that could affect the seismic segmentation of the arc and limit the along strike propagation of seismic ruptures the moment deficit builds up at a rate of 15 1 1 10 19 n m yr for the entire length of the himalaya