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

evidence for a buried fault system in the coastal plain of the carolinas and virginia implications for neotectonics in the southeastern united states geomorphic geologic and geophysical data suggest the presence of an 600 km long north northeast trending buried fault system in the coastal plain of the carolinas and virginia herein named the east coast fault system the east coast fault system is expressed by anomalous changes in fluvial geomorphology that locally coincide with one or more of the following features linear aeromagnetic anomalies buried faults interpreted from seismic reflection data surface faults offsetting pliocene pleistocene surficial units locally brecciated phyllites and argillites gently upwarped sediments topographic highs and seismicity near summerville south carolina river anomalies where the rivers traverse unconsolidated upper pleistocene holocene flood plain sediments are evidence of deformation along the east coast fault system during the past 130 to 10 k y which may be ongoing the fault system traverses the epicentral area of the 1886 charleston south carolina earthquake and lies west of paleoliquefaction sites along the outer south carolina coastal plain thus the fault system could be the source of the charleston earthquake and other large prehistoric earthquakes therefore confirmation and demarcation of the east coast fault system and elucidation of its history will help better assess seismic hazards in the southeastern united states

the surface accumulation and ablation of a coastal blue ice area near cap prudhomme terre adelie antarctica a record of accumulation and ablation from a network of 47 stakes at a coastal blue ice area in terre adelie antarctica is presented and analyzed the record covers early 2004 to early 2006 from 25 field surveys including some in austral winter the two years are very different with a virtually null surface mass balance during the 2004 winter but large accumulation during the 2005 winter a snow ice energy and mass balance model is used to reproduce the accumulation and ablation record a parameterization for snow erosion by wind is included input meteorology is from the european centre for medium range weather forecasts ecmwf analyses and forecasts corrected using 1 year of local meteorological observations from an automatic weather station model results agree reasonably well with the observations wind erosion is the largest contributor to ablation removing much of the precipitation sublimation and to a lesser extent melt runoff together account for 60 cm w e of ablation in 2 years mainly in summer although the record is short it confirms high interannual variability and thus high sensitivity to meteorology and climate monitoring and understanding the mass balance of such coastal blue ice areas may help monitor and detect climate change in the antarctic coastal regions

river profiles along the himalayan arc as indicators of active tectonics abstract longitudinal profiles along sixteen major transverse himalayan rivers add important constraints to models of active continental subduction and its evolution these profiles are characterized by a zone of relatively high gradient that cannot be associated with differential resistence to erosion in all cases the base of the zone of increased gradients correlates with 1 the topographic front between the lesser and high himalayas 2 the narrow belt of intermediate magnitude thrust earthquakes 3 the main central thrust zone mct these features define a small circle in the central portion of the himalayan arc these correlations suggest that the discontinuity in the river profiles and the other features are controlled by a major tectonic boundary between the rising high himalayas and the lesser himalayas no sharp increases in gradient are observed near the main boundary thrust mbt except on a few rivers such as the jhelum or kundar where the mbt lies close to both the mct and the seismic belt thus it is unlikely that the mbt is a major tectonic boundary the diversion of river courses along the mbt and around anticlines in the sub himalayas has probably been caused by aggradation near the rosion deposition boundary upstream of uplifts in the mahabharat range and sub himalayas a parallel is drawn between the himalayas and new guinea based on the hypothesis that continent arc collision of the type occurring in northern australia preceded continent continent collision in the himalayas the present sedimentary tectonic phase in new guinea resembles the subathu paleocene eocene phase in the himalayas incipient counterparts of the major himalayan structures including the mct and the mbt are recognized in new guinea the drainage patterns in the himalayas and in new guinea bear a similar relation to major structures this suggests that 1 the tectonic evolution of the himalayas has been rather uniform since early stages of collision and 2 the himalayan drainage was also formed at these early stages and is therefore antecedent to the rise of the high himalayas

quaternary of the pantanal west central brazil abstract the pantanal is a tectonic depression located at the left margin of the upper paraguay river the paraguay is the trunk river of an alluvial depositional tract composed by several large marginal alluvial fans the taquari fan being the largest one the present landscape is a complex tropical wetland characterized by month long floods every year with geomorphic features derived from the present conditions and others inherited from successive pleistocene and holocene climates some areas containing ponds are landscape relicts generated by eolian deflation during the last glacial maximum many ponds closed depressions isolated from the superficial waters by vegetated crescent ridges of fine sands were interpreted as salt pans bordered by lunette sand dunes initiation of the modern wetland has occurred during the pleistocene holocene transition with the change to a more humid climate and the individualization of lacustrine systems active tectonics has been playing an important role in the development of the pantanal landscape nowadays the paraguay river meanders in a large flood plain with extensive swamp surfaces being structurally constrained by faults in the west border of the basin sedimentation within the pantanal wetland is also affected by tectonic activity especially along faults associated with the transbrasiliano lineament

fluvial dynamics of an anabranching river system in himalayan foreland basin baghmati river north bihar plains india abstract anabranching river systems are now regarded as a separate class in river classifications owing to their distinctive morphological hydrological characteristics and fluvial processes a better understanding of anabranching rivers still needs detailed data from different environmental and geographical settings this paper presents a detailed account of an anabranching river system from the himalayan foreland basin the baghmati river system from north bihar plains eastern india provides a typical example of an anabranching river system located in the interfan area between the kosi and the gandak megafans the river system is braided in upstream reaches and meandering in downstream reaches but the midstream anabranching reach is characterized by low width depth ratio 11 16 gentle gradient 0 00018 0 00015 variable peak discharge frequent flooding and high sediment load the anabranching in the midstream reaches is a response to its inability to transport high sediment load due to gentle channel slope and dominance of aggradation process the development of anabranches is related to rapid and frequent avulsions of the river channels with eight major avulsions observed in the 30 km wide floodplain in the last 230 years the decadal scale avulsion history of the baghmati river system makes it hyperavulsive and the major causative factors for such channel instability are sedimentological readjustments and active tectonics in the basin area

historical geomorphology and pedology of the gandak megafan middle gangetic plains india the gandak megafan of eastern uttar pradesh and northwestern bihar lies in the middle gangetic plains the gandak river has shifted about 80 km to the east due to tilting in the last 5000 years this has created a soil chronoassociation similar to the chronosequences found on some flights of river terraces this chronoassociation has five members qgd1 5 they are distinguished on the basis of profile development clay mineralogy and calcium carbonate content chlorite transforms to vermiculite on a large scale from qgd1 to qgd3 and decreases drastically in member qgd4 kaolinite and interstratified kaolinite smectite are abundant in the older members of the chronoassociation the youngest soils qgd1 500 b p while qgd3 soils like those on the older gandak plain and old rapti plains date back to 2500 b p qgd4 soils like those on the oldest gandak plain are dated as 5000 years b p whilst the oldest qgd5 soils as on the old ghaghra plain and ganga ghaghra interfluve date back to 10000 b p these soils which include pedogenic calcite and a saline epipedon indicate a dry climatic spell during the period 9000 11000 b p faults developed on the megafan are not related to the basement structures

active transverse features in the central portion of the himalaya abstract many transverse lineaments or faults across the himalaya are already known interpretation of satellite images of the central portion of the himalaya given here adds to that number and suggests their continuity from the himalaya to its foredeep several such faults appear to be seismically active their shear motion recognized from geologic data and focal mechanism solutions compares well with a classical stress model when applied to northward progress of india under the himalayan collision front

present weather sensor tests for measuring drifting snow in antarctica blowing snow accounts for a major component of the surface mass balance near the coast measurements of precipitation and blowing snow are scarce therefore collecting data would allow testing numerical models on mass flux over that region a present weather station pws biral vpf730 has been set up at the coast in cap prud homme station 5km away from dumont d urville ddu firstly to quantify precipitation as we could expect determination of blowing snow fluxes from the pws data we first choose to test such a device on our experimental site the lac blanc pass an empirical calibration was done with a spc snow particle counter even if the physics of phenomenon was not well capture the fluxes outputs are better than those from the flowcapt the first data from antarctica were re analyzed the new calibration seems to be accurate for estimating the high blowing snow flux with an interrogation for the precipitation effects

a two dimensional tidal model for the mediterranean sea the tidal propagation in the mediterranean sea is described through a high resolution two dimensional hydrodynamic model forced by the equilibrium tide and the incoming tide at the strait of gibraltar the four most significant constituents m2 s2 k1 and o1 are included in the model good agreement with a set of 63 coastal gauges is achieved the significance of the equilibrium tide and the forcing at the open boundary is investigated the incoming wave from the strait of gibraltar is important in tuning the tides in the whole of the mediterranean for the north aegean sea the solution without the forcing at gibraltar results in a doubling of the amplitudes of the semidiurnal tides the estimated energy dissipation due to bottom friction is 8 8 108 w the major area of dissipation is the gulf of gabes energy fluxes through the major straits are calculated

response of alluvial rivers to slow active tectonic movement alluvial rivers respond to valley slope deformation caused by active tectonics in various ways depending on the rate and amount of surficial deformation and on the type of river on the basis of experimental results and field examples hypothetical models of river response to anticlinal uplift and synclinal subsidence were developed for different types of alluvial rivers an experimental braided channel responded to anticlinal uplift across the channel with degradation and terrace formation in the central part of the uplift with subsidence aggradation in the central reach was the main response transverse bars developed downstream of the subsidence axis an experimental meandering channel responded to slope steepening with a sinuosity increase bank erosion and point bar growth occurred downstream of the anticlinal axis and upstream of the synclinal axis upstream of the uplift axis and downstream of the subsidence axis where the slope was flattened water flooded over bars local convexity in longitudinal profiles of the middle rio grande new mexico is considered to be formed by a domal uplift local aggradation and degradation could be explained by the effect of uplift the san joaquin river california which is now highly controlled does not show clear adjustment to the rapid subsidence due to ground water withdrawal it shows however a channel pattern adjustment to active tectonic subsidence that has been occurring for a long time the san antonio and guadalupe rivers in texas both increase their sinuosity significantly where monoclinal movements steepen valley slopes

present day kinematics of asia derived from geologic fault rates active fault geometry available quaternary rates on major faults and the far field plate motion are used to determine crustal kinematics in the collision zone between india and asia using a finite element formalism to construct a spherical shell model of the asian continent with embedded faults we seek a velocity solution approaching the motion of rigid blocks by minimizing the elastic strain energy in the fault bounded blocks by doing so we test the assumption that long term deformation within continents is mostly localized into major faults in the solution fault motion accounts for more than 80 of the deformation allowing us to describe our velocity model in terms of quasi rigid block rotations on the sphere south china is rotating clockwise about a pole located southwest of borneo implying an e ese velocity vector of 11 mm yr for a point at shanghai in agreement with the velocity vector determined by very long baseline interferometry heki et al 1995 the eastward movement of south china is accommodated by oblique extension along the red river fault at a rate of 10 5 mm yr in the south and by the combination of left lateral strike slip motion on the qinling dabie shan fault and the counterclockwise rotation of the ordos and adjacent blocks in the north the tarim rotates clockwise with respect to dzungaria about a pole located at 44 n 92 e consistent with increasing crustal shortening toward the west throughout the tien shan assuming incompressibility a crustal volume budget over a domain encompassing the tertiary mountain ranges in asia shows that over the last 10 000 years 73 4 of the north south shortening between india and asia has been absorbed by thickening of the lithosphere and 27 has been accommodated by lateral extrusion of continental blocks the present day predominance of thickening in asia results from the relatively slow eastward motion of south china controlled by strike slip faulting in the qinling shan and oblique extension in northeastern china

alluvial river response to neotectonic deformation in louisiana and mississippi repeat geodetic surveys show uplift of the monroe and wiggins anticlines in louisiana and mississippi there are deformed quaternary terraces which indicate long term deformation in the valleys of the alluvial rivers that cross these structures and there are floodplain and channel convexities that provide evidence of modern deformation in addition the channels show significant variations of morphology sinuosity gradient and depth and behavior appropriate to reaches of increased and decreased valley slope these alluvial rivers are adjusting to modern deformation and their adjustment confirms two geodetic leveling anomalies

foreland sedimentation in himalayan tectonic regime a relook at the orogenic process by raiverman v 2002 bishen singh mahendra pal singh publishers 23 a connaught place p o box 137 dehradun 248 001 india 378 pp price us 125

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

geomorphic and sedimentary response of rivers to tectonic deformation a brief review and critique of a tool for recognizing subtle epeirogenic deformation in modern and ancient settings abstract rivers are extremely sensitive to subtle changes in their grade caused by tectonic tilting as such recognition of tectonic tilting effects on rivers and their resultant sediments can be a useful tool for identifying the often cryptic warping associated with incipient and smaller scale epeirogenic deformation in both modern and ancient settings tectonic warping may result in either longitudinal parallel to floodplain orientation or lateral normal to floodplain orientation tilting of alluvial river profiles alluvial rivers may respond to deformation of longitudinal profile by 1 deflection around zones of uplift and into zones of subsidence 2 aggradation in backtilted and degradation in foretilted reaches 3 compensation of slope alteration by shifts in channel pattern 4 increase in frequency of overbank flooding for foretilted and decrease for backtilted reaches and 5 increased bedload grain size in foretilted reaches and decreased bedload grain size in backtilted reaches lateral tilting causes down tilt avulsion of streams where tilt rates are high and steady down tilt migration combing where tilt rates are lower each of the above effects may have profound impacts on lithofacies geometry and distribution that may potentially be preserved in the rock record fluvial sedimentary evidence for past tilting is traditionally based on the assumption that depositional features reminiscent of modern fluvial tectonic effects are evidence for past tectonic effects where it is closely associated with historically active structures or where non tectonic causes cannot be invoked however caution must be exercised when using these effects as criteria for past or current tectonic warping as these effects may be caused by non tectonic factors these non tectonic causes must be eliminated before tectonic interpretations are made

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

back analysis of drifting snow measurements over an instrumented mountainous site the nemo numerical model of drifting snow whose general outlines are presented in this paper is based on a physical model for saltation and turbulent diffusion the model needs a set of input parameters including fall velocity threshold shear velocity shear velocity mass concentration and roughness which are obtained from empirical formulae and wind speed measured at a given height to better determine the required field data in an alpine context our experimental site col du lac blanc 2700 m a s l french alps was first equipped with one anemometer and blowing snow acoustic sensors which proved not to be accurate enough for research purposes in the current state of development even though a new calibration curve was used we therefore set up a snow particle counter and we returned to the traditional robust mechanical traps and a 10 m mast with six anemometers two temperature sensors and a depth sensor to better determine friction velocity and aerodynamic roughness based on the studied drifting snow events we conclude 1 the proportionality of the aerodynamic roughness to the square of the friction velocity was confirmed but with a varying proportionality ratio depending on the snowdrift event 2 values of s u f were relatively well approximated by empirical formulae from data originating from antarctica and 3 snowdrift concentration profiles obtained by pomeroy s semi empirical formulae for the saltation layer coupled with a theoretical approach for the diffusion layer overestimated the concentration profiles for the studied blowing snow event

antarctic precipitation and climate change predictions horizontal resolution and margin vs plateau issues all climate models participating in the fourth assessment report of the intergovernmental panel on climate change as made available by the program for climate model diagnosis and intercomparison pcmdi as the coupled model intercomparison project 3 cmip3 archive predict a significant surface warming of antarctica by the end of the 21st century under a moderate sresa1b greenhouse gas scenario all models but one predict a concurrent precipitation increase but with a large scatter of results the models with finer horizontal resolution tend to predict a larger precipitation increase because modeled antarctic surface mass balance is known to be sensitive to horizontal resolution extrapolating predictions from the different models with respect to model resolution may provide simple yet better multi model estimates of antarctic precipitation change than mere averaging or even more complex approaches using such extrapolation a conservative estimate of the predicted precipitation increase at the end of the 21st century is 30 kg m 2 a 1 on the grounded ice sheet corresponding to a 1 mm a 1 sea level rise about three quarters of this rise originates from the marginal regions of the antarctic ice sheet with surface elevation below 2250 m this is where field programs are most urgently needed to better understand and monitor accumulation at the surface of antarctica and to improve and verify prediction models