drainage sediment transport and denudation rates on the nanga parbat himalaya pakistan the nanga parbat himalaya presents some of the greatest relief on earth yet sediment production and denudation rates have only been sporadically addressed we utilized field measurements and computer models to estimate bank full discharge sediment transport and denudation rates for the raikot and buldar drainage basins north slope of nanga parbat and the upper reach of the rupal drainage basin south slope the overall tasks of determining stream flow conditions in such a dynamic geomorphic setting is challenging no gage data exist for these drainage basins and the overall character of the drainage basins high relief steep flow gradients and turbulent flow conditions does not lend itself to either ready access or complete profiling cross sectional profiles were surveyed through selected reaches of these drainage basins these data were then incorporated into software winxspro that aids in the characterization stage discharge velocity and shear stress of high altitude steep mountain stream conditions complete field measurements of channel depths were rarely possible except at several bridges where the middle of the channel could actually be straddled and probed and when coupled with velocity measurements provided discrete points of field measured discharge calculations these points were then used to calibrate winxspro results for the same reach and provided a confidence level for computer generated results flow calculations suggest that under near bank full conditions the upper raikot drainage basin produces discharges of 61 cm and moves about 11 000 tons day 1 9980 tons day 1 of sediment through its channel bank full conditions on the upper portion of the rupal drainage basin generate discharges of 84 cm and moves only about 3800 tons day 1 3450 tons day 1 of sediment although the upper rupal drainage basin moves more water the lower slope of the drainage basin 0 03 generates a much smaller shear stress 461 pa than does the higher slope 0 12 of the upper raikot drainage basin 1925 pa dissolved and suspended sediment loads were measured from water sediment samples collected throughout the day and night over a period of 10 days at the height of the summer melt season but proved to be a minor variable in transport flux channel bed loads were measured using a pebble count method of bank material and then used to generate ratings curves of bed loads relative to discharge volumes when coupled with discharge data and basin area mean annual sediment yield and denudation rates for nanga parbat are produced denudation rates calculated in this fashion range from 0 2 mm year 1 in the slower more sluggish rupal drainage basin to almost 6 mm year 1 in the steeper faster flowing raikot and buldar drainage basins

nature and timing of large landslides in the himalaya and transhimalaya of northern india four large landslides each with a debris volume 10 6 m 3 in the himalaya and transhimalaya of northern india were examined mapped and dated using 10 be terrestrial cosmogenic radionuclide surface exposure dating the landslides date to 7 7 1 0 ka darcha 7 9 0 8 ka patseo 6 6 0 4 ka kelang serai and 8 5 0 5 ka chilam comparison of slip surface dips and physically reasonable angles of internal friction suggests that the landslides may have been triggered by increased pore water pressure seismic shaking or a combination of these two processes however the steepness of discontinuities in the darcha rock slope suggests that it was more likely to have started as a consequence of gravitationally induced buckling of planar slabs deglaciation of the region occurred more than 2000 years before the darcha patseo and kelang serai landslides it is unlikely that glacial debuttressing was responsible for triggering the landslides the four landslides their causes potential triggers and mechanisms and their ages are compared to 12 previously dated large landslides in the region fourteen of the 16 dated landslides occurred during periods of intensified monsoons seismic shaking however cannot be ruled out as a mechanism for landslide initiation because the himalaya has experienced great earthquakes on centennial to millennial timescales the average holocene landscape lowering due to large landslides for the lahul region which contains the darcha patseo and kelang serai landslides is w0 12 mm yr previously published large landslide landscape lowering rates for the himalaya differ significantly furthermore regional glacial and fluvial denudation rates for the himalaya are more than an order of magnitude greater this difference highlights the lack of large landslide data lack of chronology problems associated with single catchment large landslide based calculations and the need for regional landscape lowering determinations over a standardized time period

ice dams outburst floods and glacial incision at the western margin of the tibetan plateau a 100 k y chronology from the shyok valley karakoram some of the largest and most erosive floods on earth result from the failure of glacial dams while potentially cataclysmic ice dams are recognized to have repeatedly formed along ice sheet margins much less is known about the frequency and longevity of ice dams caused by mountain glaciers and their impact on landscape evolution here we present field observations and results from cosmogenic nuclide dating that allow reconstructing a 100 k y long history of glacial damming in the shyok valley eastern karakoram south asia our field observations provide evidence that asia s second longest glacier the siachen once extended for over 180 km and blocked the shyok river during the penultimate glacial period leading to upstream deposition of a more than 400 m thick fluvio lacustrine valley fill 10 be depth profile modeling indicates that glacial damming ended with the onset of the eemian interglacial and that the shyok river subsequently incised the valley fill at an average rate of 4 7 m k y 1 comparison with contemporary ice dammed lakes in the karakoram and elsewhere suggests recurring outburst floods during the aggradation period while over 25 cycles of fining upward lake deposits within the valley fill indicate impounding of floods from farther upstream despite prolonged damming the net effect of this and probably earlier damming episodes by the siachen glacier is dominated by glacial erosion in excess of fluvial incision as evidenced by a pronounced overdeepening that follows the glaciated valley reach strikingly similar overdeepened valleys at all major confluences of the shyok and indus rivers with karakoram tributaries indicate that glacial dams and subsequent outburst floods have been widespread and frequent in this region during the quaternary our study suggests that the interaction of karakoram glaciers with the shyok and indus rivers promoted valley incision and headward erosion into the western margin of the tibetan plateau

rock avalanches and the pace of late quaternary development of river valleys in the karakoram himalaya we discuss the implications of a set of terrestrial cosmogenic nuclide tcn ages on blocky cross valley deposits of large rock avalanches along upper indus streams the dated deposits are key to understanding late quaternary events that play a major role in landscape evolution in the karakoram himalaya the landslides occurred between 3 and 8 ka ago challenging existing chronologies of events along indus streams the tcn ages may support a mid holocene climatic role in preparing slopes for failure but the balance of evidence suggests that large earthquakes triggered the landslides each landslide dammed the indus or a major tributary and controlled base level and sedimentation for millennia they produced landforms long regarded as characteristic of the region including extensive lacustrine deposits flights of river terraces epigenetic gorges and sediment fans until the 1990s most of the landslides were interpreted as moraines related lacustrine and other sediments continue to be attributed to glacial damming and stream terraces to tectonic processes generally they were seen to originate tens of thousands to hundreds of thousands of years earlier than the new ages require instead we argue that they record interactions among different geomorphic processes in landslide fragmented valleys during the holocene rather than being geomorphic markers of tectonic and climatic events the landslides have buffered or redirected climatic and tectonic forcing in such an active orogen millennia long episodes of zero net bedrock incision at each site are surprising however rates of sedimentation above landslide barriers and erosion controlled by their breaching are close to today9s high measured rates for geomorphic activity we propose that landslide fragmented rivers may in fact characterize interglaciations and future patterns of upper indus landscape evolution at time scales of 10 3 to 10 4 years

influence of secular variation of the geomagnetic field on production rates of in situ produced cosmogenic nuclides abstract scaling factors are presented that allow a full description of the cosmic ray flux modulation during secular variation of the geomagnetic field these scaling factors are analogous to those determined in a similar work dunai t j earth planet sci lett 2000 176 157 169 that were accurate for field strengths equivalent to present day field strength but cannot accommodate field strength variations strategies to derive the relevant geomagnetic field parameters are discussed and are tested with existing production rate calibrations for 3 he a production rate of 103 4 2 atoms g olivine yr sea level and for zero cutoff rigidity was derived from calibration sites from hawaii western usa and canary islands covering the time range of 2 281 kyr

postglacial topographic evolution of glaciated valleys a stochastic landscape evolution model the retreat of valley glaciers has a dramatic effect on the stability of glaciated valleys and exerts a prolonged influence on the subsequent fluvial sediment transport regime we have studied the evolution of an idealized glaciated valley during the period following retreat of ice using a numerical model the model incorporates a stochastic process to represent deepseated landsliding non linear diffusion to represent shallow landsliding and an approximation of the bagnold relation to represent fluvial sediment transport it was calibrated using field data from several recent surveys within british columbia canada we present ensemble model results and compare them with results from a deterministic linear diffusion model to show that explicit representation of large landslides is necessary to reproduce the morphology and channel network structure of a typical postglacial valley our model predicts a rapid rate of fluvial sediment transport following deglaciation with a subsequent gradual decline similar to that inferred for holocene time we also describe how changes in the model parameters affect the estimated magnitude and duration of the paraglacial sediment pulse

supply and removal of sediment in a landslide dominated mountain belt central range taiwan abstract a strong coupling between hillslope and valley systems is often inferred for mountain landscapes dominated by bedrock landsliding we reveal the nature of this link using data sets on landsliding and sediment transport from two montane catchments draining the eastern central range of taiwan here the magnitude frequency distribution of landslides can be modeled by a robust power law but this scale invariance is not mirrored in the sediment discharge at the mountain front instead downstream sediment loads reflect a complex response to both sediment supply and ambient hydraulic conditions the rivers do not transport significant amounts of sediment unless it is provided by hillslope mass wasting in the catchment removal of landslide debris is a function of the transport capacity of the stream at the site of entry thus there is a dual supply and transport control on sediment loads in bedrock floored streams over a monitoring period of 25 yr the bulk of the sediment leaving the mountain bel

a 13 000 year climate record from western tibet although the tibetan plateau is important in influencing the atmospheric circulation of the northern hemisphere1 3 there are only a few continuous palaeoclimate records available and these are limited to the plateau s northeastern margin4 6 here we present a 13 000 yr record from sumxi co western tibet constructed from both lake core and shoreline studies which shows that conditions in the early middle holocene were warmer and wetter than at present these results confirm model predictions of an intensified monsoon over the region at 9 000 yr bp owing to an orbitally induced increase in summer insolation7 8 we also find evidence for warm humid pulses at 12 500 and 10 000 yr bp in phase with the steps of the last deglaciation and for a return to cold dry conditions at 11 10 000 yr bp none of which can be explained by orbital variations the existence of the cold episode confirms that the cooling associated with the younger dry as event occurred in continental china6 9 and provides further evidence of the global nature of this event10

comparing e field changes aloft to lightning mapping data 1 a newly developed balloon borne instrument contains electric and magnetic sensors for determining how lightning alters electric field vectors relative to a coordinate system fixed with the earth by combining data from this instrument with results from the compact lightning mapping array lma at langmuir laboratory in central new mexico and the national lightning detection network nldn charge transported to ground by several strokes in a cloud to ground cg lightning flash can be quantified as the flash progresses the locations of the charge centers drained by successive strokes are seen to move further from the ground strike point using this new instrument and two different models to map lma source points onto charge centers the charge transported in an intracloud ic flash is also estimated details of the instrument design and data analysis are also presented

analysis of landslide dams induced by the 2008 wenchuan earthquake abstract landslide dams caused by earthquakes are extremely hazardous disruptions of the flow of water and sediment in mountain rivers capable of delivering large outburst floods that may devastate downstream areas we analyzed a unique inventory of 828 landslide dams triggered by the m w 7 9 2008 wenchuan tectonic earthquake china constituting 1 4 of the 60 000 coseismic slope failures mapped and attributed to this event while 501 landslides blocked the rivers completely the remainder caused only partial damming or channel diversion the spatial distribution of landslide dams follows the same trend of that of the total landslide distribution with landslide dams being most abundant in the steep watersheds of the hanging wall of the yingxiu beichuan thrust fault and in the northeastern part of the strike slip fault near qingchuan besides the co seismic landslide density the river width also played a key role in determining the landslide dam formation narrow rivers are more prone to be dammed than the wide rivers the correlation between river width and landslide dam volume follows a linear relation which can be used to roughly estimate the dam formation possibility however the applicability of this correlation needs to be validated in other regions the decay failure rate of dams defined here as the percentage of the number and area of landslide dams that have failed over time shows that 25 of dams accounting for 30 of total landslide dam area failed one week after the earthquake these percentages increased to 60 within 1 month and to 90 within 1 year the geomorphometric parameters were analyzed revealing power law relations between landslide area and dam width landslide source area and dam area as well as lake area and lake volume the inventory presented in this study will enrich the worldwide earthquake induced landslide dam database and will also contribute to a better understanding of the post earthquake dam decay

frequency and hazard of large rock avalanches in the central southern alps new zealand forty two rock avalanche deposits with volumes ranging from a chosen lower threshold of 1 10 6 m 3 up to 500 10 6 m 3 have been identified in a 10 000 km 2 area of the central southern alps new zealand the observed frequency of one per 244 yr over 10 250 yr is biased by erosion a nearly complete sample of the past 1 700 yr indicates a frequency of 1 per 94 yr on the average the largest rock avalanche in any century is 56 10 6 m 3 and in any millennium 103 10 6 m 3 at about one per century most large rock avalanches are probably triggered by large earthquakes and only a few by large storms the risk of rock avalanche debris reaching a specified distance from a source of known elevation is given by a simple stochastic model locally calibrated to assess rock avalanche hazard

landslides and quaternary climate changes the state of the art abstract climatic factors are considered major causes and triggers of slope instability but the palaeoclimatic implications of landslides have not yet been systematically reviewed as inferred from landslides dated to the late glacial and holocene glacial interglacial transitions are the major intervals of enhanced landsliding but the length of this interval varies between distinct types of landscapes mass movements in non glaciated temperate mountain ranges arid and tropical regions and coastal areas intensified soon after the onset of the holocene alongside the warming and wetting of the climate whereas large rock slides in areas within the limits of pleistocene glaciations mostly show a millennial scale time lag with respect to glacier withdrawal although the incidence of landslides was ubiquitous throughout the holocene the mid to late holocene transition 5 4 ka was especially favourable for the origin of landslides across distinct types of landscapes indicating a strengthened role of mass movements during the culmination phases of interglacial climate optima in addition growing evidence suggests that the enhanced activity of landslides occurred during warmer interstadial conditions which is best demonstrated in the temporal coincidence of arid zone landslides with quaternary pluvials future progress in the understanding of the relationships between landslides and quaternary climate changes should benefit from the i extension of datasets of dated landslides ii geographical expansion of dating studies to regions with a lack of chronologically determined landslides e g tropics iii improvement of landslide dating strategies involving the incorporation of independent palaeoclimatic proxies and iv wider incorporation of numerical modeling within landslide dating studies

rainfall thresholds for landsliding in the himalayas of nepal landsliding of the hillslope regolith is an important source of sediment to the fluvial network in the unglaciated portions of the himalayas of nepal these landslides can produce abrupt increases of up to three orders of magnitude in the fluvial sediment load in less than a day an analysis of 3 years of daily sediment load and daily rainfall data defines a relationship between monsoonal rainfall and the triggering of landslides in the annapurna region of nepal two distinct rainfall thresholds a seasonal accumulation and a daily total must be overcome before landslides are initiated to explore the geomorphological controls on these thresholds we develop a slope stability model driven by daily rainfall data which accounts for changes in regolith moisture the pattern of rainfall thresholds predicted by the model is similar to the field data including the decrease in the daily rainfall threshold as the seasonal rainfall accumulation increases results from the model suggest that for a given hillslope regolith thickness determines the seasonal rainfall necessary for failure whereas slope angle controls the daily rainfall required for failure d 2004 elsevier b v all rights reserved

reduced himalayan sediment production 8 myr ago despite an intensified monsoon uplift of the tibetan plateau about 7 8 myr ago1 2 may have been responsible3 5 for the apparent intensification of the asian monsoon 6 10 around that time increases in the oceanic 87sr 86sr ratio during the neogene period have been attributed11 12 to increased erosion from the himalayan orogen it has been suggested that the monsoonal intensification may have enhanced overall erosion rates in the region5 13 if this were the case sediment accumulation rates would have increased in the surrounding basins at this time here we present a reanalysis of stratigraphic data from the indo gangetic foreland and the bengal fan which demonstrates that both of these basins experienced a decline in sediment accumulation rates 8 myr ago thus it seems that monsoonal intensification was accompanied by a decrease in mechanical weathering this decrease could be due to reduced tectonic activity decreased himalayan glaciation or slope stabilization from dense plant cover

diagnostic characteristics and paleodynamics of supraglacial rock avalanches innerdalen western norway abstract misinterpretation of rock avalanche deposits in mountain environments is not uncommon because of the complex interactions between rock avalanches and glaciers this paper for the first time presents a detailed description of suspicious rock boulder deposits which are remnants of a rock avalanche onto a late pleistocene glacier the boulder deposits cover around 1 1 km 2 and are distributed over an area of around 7 5 km 2 and a variety of landforms three closely nested distinct terminal moraines 0 45 km 2 and dislocated terminal moraines 0 34 km 2 entirely built up of large boulders lateral moraines that decrease in elevation over a short distance and connect to the terminal moraines small patches 0 02 km 2 of boulders that occur in islands on a peat dominated valley floor and large patches of boulder fields 0 25 km 2 in size hanging 350 m above the valley floor the latter are disconnected from any potential source area 10 be cosmogenic nuclide ages of the three terminal moraines give an indistinguishable late pleistocene age of 13 6 1 4 ka whereas the largest boulder field that is located on the opposite side of the valley from the failed mountain yields a 10 be age of 14 1 0 4 ka which is slightly older but indistinguishable from the moraine deposits within uncertainty margins all boulder deposits add up to a volume of 31 10 6 m 3 the interpretation of a single rock avalanche source for those landforms is further confirmed by numerical runout modeling using dan3d a failure of the entire volume from skarfjellet mountain would result in a runout pattern that is identical to that of the distributed boulder fields when considering that the valley was filled with a glacier around 350 m thick the rock avalanche would not reach the position of the terminal moraines however a glacial re advance could have transported the boulders to that position the late pleistocene rock avalanche was followed by a holocene rock avalanche with a volume of 23 10 6 m 3 and a typical lobate deposit damming the innerdalen valley and creating a lake 10 be ages indicate that this event occurred 7 97 0 94 ka ago structural measurements performed on high resolution lidar scans show a strongly jointed source rock with three joint sets with dip dip direction 81 034 86 331 and 77 354 and a foliation with 22 003 the kinematic of the failures can thus be a combination of small scale wedge failures and planar sliding on shallow dipping foliation our detailed description can enable a better identification and interpretation of similar deposits in other mountain areas

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 catastrophic rock avalanches in the central apennines italy relationships with inherited tectonic features gravity driven deformations and the geodynamic frame abstract five cases of quaternary rock avalanches detached from carbonate mountain ridges in the central apennines are presented due to the large amount of rock masses involved the width of accumulation and detachment areas and the damming in the host environment the analysed rock avalanches can be considered as catastrophic rock slope failures sporadic events in a mountain region characterized by low elevation but where mountain ridges can have a relative elevation of up to 1 km above the lowermost valley floors the geological setting of tectonic structures that originated during the apennine orogenesis influenced rock avalanche characteristics determining the location and shape of detachment areas the kind of rock mass involved and the failure mechanisms two main types have been identified i forelimb rock slide avalanches frsa such as the lettopalena and mt arezzo rock avalanche which involved cenozoic heterogeneous sequences of carbonate ramp deposits detached from box shaped source areas according to a rock sliding mechanism and ii backlimb slide wedge rock avalanches bswra such as the campo di giove scanno and celano rock avalanches that detached from sub circular source areas carved on fault bounded ridges and involving meso cenozoic carbonate rocks with a combined sliding and rock wedge failure mechanism the campo di giove lettopalena and scanno rock avalanches originated from mountain ridges bounded by inactive fault zones and undergoing deep seated gravitational slope deformations dsgsds at the mountain scale these three rock slope failures are considered as isolated events of long lasting deformative processes featuring creep deformation gravity driven deformations firstly generated as a response to stacking processes and synchronous normal faulting during the neogene early pleistocene apennine tectonics in particular the caramanico fault system cfs and the genzana fault gf bordering the carbonate ridges from which the campo di giove and scanno rock avalanches originated respectively are here considered as backlimb collapse structures accommodating the passive uplift and deformation of positive tectonic structures gravity driven deformations persisted during the post early pleistocene dome like uplift of the whole apennine region the regional uplift created the first order 200 km topographic wave length of the belt i e a periodic loading which has been balanced by the deflection of the apennine crust and lithosphere on the contrary shorter topographic wave lengths inherited from former thrusting and synchronous normal faulting determined local isostatic imbalances bearing a large potential for the mature development of dsgsds on mountain ridges favoured also by lateral unloading due to linear erosion and increase of topographic stress thus a cause effect relationship is hypothesized between the geodynamic evolution of the belt and mountain sized gravity driven deformations including large rock slope failures

incision and differential bedrock uplift along the indus river near nanga parbat pakistan himalaya from 10be and 26al exposure age dating of bedrock straths abstract well preserved river cut bedrock surfaces straths abandoned by the progressive incision of the indus river in northern pakistan were dated using in situ cosmogenic 10 be and 26 al exposure age dating measurements on young and modern straths show no significant ingrowth of 10 be and 26 al implying that strath exposure ages closely approximate their abandonment age strath exposure ages range up to 65 ka and increase with height above the river the straths can be divided into two groups low straths dated at about 7 ka which yield very rapid bedrock incision rates 9 12 m ka and high straths 7 ka in age which yield somewhat slower incision rates 1 6 m ka incision rates for both groups increase by 1 3 m ka downstream toward an active reverse fault the raikot fault that forms the western border of the nanga parbat haramosh massif nphm the downstream increases in incision rates for the low straths mimic downstream increases in the modern gradient suggesting that bedrock incision rates have been proportional to stream power over the last 7 ka gradient increases are probably the result of the creation of knickpoints by bedrock uplift along the raikot fault the longitudinal profile and steep gorge of the indus river in the study area indicate that bedrock incision appears to keep pace with differential vertical motions between the nphm and surrounding regions thus the 1 3 m ka difference in incision rates likely reflects the differential bedrock uplift rate between the nphm and the skardu basin the differential incision rate is consistent with differential exhumation rates obtained from apatite fission track ages assuming geotherms of 80 90 c km in the nphm and 35 c km in the skardu basin this relation suggests that rapid bedrock incision of at least 1 3 m ka has persisted within the nphm for the last 0 5 ma the acceleration of incision rates throughout the study area since 15 ka is likely to be a climatic signal that records an increase in the discharge and or sediment load of the indus river in the study area related to deglaciation of the surrounding terrane

hunza river watershed landslide and related features inventory mapping this study summarizes the continuation of a series of regional landslide inventories undertaken in northern pakistan mass wasting appears to be the dominant process shaping the morphology of the main river channel in the hunza river watershed the project included assembling an inventory of historic mass wasting features in the basin especially those along the hunza river a hillshade topographic map was created by stitching aster digital elevation models dems with 30 m resolution topographic sheets of 40 m resolution using arcgis the methodology utilizes anomalous topographic expression i e parallel and converging drainage patterns divergent contours crenulated contours and isolated knobs to identify landslide features the screening process includes examination of topographic anomalies and inconsistencies which are typical of landslides and related mass wasting features the mapped landslide features included a number of historic landslides in the area historic landslide damming of the hunza river has occurred at attabad boultar glacier gannish chiss and ganesh saukien the outbreak floods associated with the overtopping of these recent landslide dams often leave anomalous geomorphic signatures which were identified in the terrain analysis and helped validate the interpretations made as part of this study such products serve as guide maps for more detailed analyses of specific sites as might be under consideration for structures highways tunnels dams powerhouses or utility corridors

quaternary lacustrine deposits in a high energy semi arid mountain environment karakoram mountains northern pakistan impressive quaternary lacustrine deposits are present as terrace remnants through out the karakoram mountains northern pakistan they are mainly the result of damming of drainage systems during glacial advances or by catastrophic mass movement deposits the longevity of most lakes is relatively short in the order of years to tens of yeaa but sedimentation rates are extremely high as a consequence of the high sediment loads within the rivers this results in deposits that frequently exceed 10 rn in thickness the sediments comprise dominantly planar bedded massive and less commonly planar laminated silts comprising detrital quartz brml of qwtermry science feldspar mica calcite chlorite and illite a facies model for lacustrine sedimentation in a high energy semi arid high mountain region is presented using case studies from a glacially dammed palaeolake glacial lake gilgit and a debris flow dammed palaeolake lake serat the rapid deposition and absence of organic material restricts the usefulness of these lacustrine sediments as proxies for palaeoenvironmental reconstruction but they are helpful in reconstructing the former extent of glaciers and illustrating the importance of high magnitude low frequency events such as landsliding as formative processes contributing to the evolution of the karakoram land scape

first cosmogenic ages for glacial deposits from the plata range 33 s new inferences for quaternary landscape evolution in the central andes this paper presents the first numerical cosmogenic ages of glacial deposits from the eastern slope of the plata peak 6000 in the arid central andes 32 s the moraines are distributed along three different valleys vallecitos angostura and las mulas in the first only one moraine was identified and no blocks could be sampled for dating the other two have evidence of two glacial advances angostura i and angostura ii the advances loma de los morteritos i and ii were recognised in the las mulas valley in both cases first and second advances are preserved at a similar altitude surface boulders on the top of moraines were sampled for be10 obtained ages are all similar and late pleistocene in age they fit very well with local stratigraphy and regional paleoclimate evidence the loma de los morteritos moraine ii located at 3000 masl dated to 25 000 years ages of 8 000 and 12 000 years were found for the angostura ii deposit 3300 masl an age was obtained for the outwash deposit identified along the el salto valley 69 000 years associated with a late pleistocene drift quantitative datings presented here improve knowledge about the glacial chronology of the plata range and quaternary stratigraphy of the central andes even though they represent a maximum age for these glacial advances new findings support the occurrence of two late pleistocene glacial advances and an older one in the blanco river valley adjusted ages around 8 000 and 25 000 years for younger stage could be evidence of the last glacial maximum lgm period for this region

luminescence chronology and climatic implication of the late quaternary glaciation in the nubra valley karakoram himalaya india abstract the present study investigates moraines outwash gravel terraces relict lake deposits and alluvial fans to reconstruct the pattern of glacier advances and associated climate variability in the nubra valley karakoram himalaya india optical chronologies obtained on stratigraphically constrained lateral moraines indicate that the oldest preserved record of glacier advance tirith ii is dated to 60 4 5 2 ka and corresponds to marine isotopic stage 4 mis 4 during mis 4 the nubra valley was occupied by 700 m thick ice cover that extended beyond the nubra shyok confluence it was followed by pulsating decrease in the ice volume vertical shrinking with an insignificant lateral recession that continued until around 42 0 3 0 ka mid mis 3 the second major glacial advance tirith i is dated to 30 2 5 ka beginning of mis 2 when the siachen glacier reached up to the nubra shyok confluence albeit with lesser ice thickness 300 m the tirith i glacier advance continued to occupy the entire nubra valley until around 18 2 1 8 ka last glacial maximum a deglaciation followed after 15 8 1 6 ka and continued until the early holocene 10 3 1 3 ka the third minor glacial advance siachen glacial advance sga is dated to the mid holocene 6 8 1 0 7 2 1 4 ka when the glacier extended below the siachen glacier snout whereas the youngest glacial expansion reached a few hundred meters below the present day snout and is dated between 1 0 0 4 ka and 0 5 0 2 ka the study suggests that glacier advances were driven by a decrease in temperature with corresponding increase in the moisture contribution due to the enhanced mid latitude westerlies during mis 4 mis 2 and the mid holocene within the age uncertainty it can be suggested that the snout proximal recessional moraines indicate marginal glacier expansion during the little ice age lia following this the glacier receded to its present position and seems to have stabilized since then unlike other himalayan glaciers the siachen glacier does not show any alarming retreat after the lia and is in conformity with recent observations suggesting that the glaciers in karakoram region are either marginally advancing or stand still

valley incision and the uplift of mountain peaks simple end member models describe the effect of isostatically compensated valley incision on the elevation of mountain peaks these models allow calculation of the maximum portion of mountain peak elevations attributable to the development of observed relief and predict general downstream patterns of ridgetop uplift in response to erosion by fluvial processes analyses of topographic profiles across major drainages of the central sierra nevada and the tibetan plateau indicate that isostatically compensated valley incision could account for at most 5 10 of the present elevation of mountain peaks in contrast analyses of topographic profiles across the himalaya show that as much as 20 30 of the present elevation of himalayan peaks could be explained by isostatically compensated valley incision the degree to which valley incision is compensated locally however depends on the flexural rigidity of the lithosphere the size of the range and its tectonic boundary conditions these results show that while a tectonic control is required for late cenozoic surface uplift of the sierra nevada a significant portion of the elevation of himalayan peaks may reflect late cenozoic valley incision on the margin of the tibetan plateau

cosmogenic dating of rock avalanches constraining quaternary stratigraphy and regional neotectonics in the argentine central andes 32 s abstract this paper provides a comprehensive review of the chronostratigraphy of six rock avalanches clustered in the northern extreme of the cordon del plata range these rock avalanches are stratigraphically related to pleistocene glacial drifts and valley fill deposits documenting the regional neotectonic activity we used cosmogenic dating tcn to directly date block surfaces of rock avalanche deposits as well as optically stimulated luminescence dating osl of paleo lakes dammed by these rock avalanches our new direct dates 17 tcn and 4 osl determine the middle to late pleistocene age of these collapses these are in contrast to the previously established chronostratigraphy based on relative dating techniques paleontological context and tephrochronology these new data help to redefine the geomorphological evolution of the mendoza river valley especially the new data indicate that the glacial stratigraphy earlier proposed must be reconsidered we redefine this stratigraphy as far as possible with our data and discuss the data in relation with other recently published results however it becomes clear that the glacial history of the mendoza valley has to be studied anew by using modern dating techniques in addition our data suggest that the carrera fault system bounding the valleys of the cordillera del plata has been active more recently than proposed earlier

landforms and landscape evolution in the skardu shigar and braldu valleys central karakoram abstract the central karakoram which includes k2 in pakistan is one of the most rapidly rising areas on earth and exhibits complex topography and extreme relief impressive valley fills and glacial landforms are present throughout the valleys the dynamics of landscape evolution of the region are currently not well understood consequently the landforms were mapped and assessed in the skardu shigar and braldu valleys to elucidate the spatio temporal scale dependencies of surface processes active in the region these valleys were examined using geomorphic field methods remote sensing geomorphometry and terrestrial cosmogenic nuclides tcns surface exposure dating the glaciers in this region have oscillated considerably throughout the late quaternary and four glacial stages have been recognized including at least six glacial advances surface processes readjusted after glacier retreat and ubiquitous mass movements and catastrophic landsliding transported material from steep slopes to valley bottoms while glaciofluvial meltwater and glacier outburst floods redistributed sediment down valley glacier geochronology and late holocene ages of the outburst flood deposits indicate that landscape evolution has been dominated by glaciation and paraglaciation during the late quaternary

recent extreme slope failures in glacial environments effects of thermal perturbation abstract this paper describes recent exceptional slope failures in high mountain glacial environments the 2002 kolka karmadon rock ice avalanche in the caucasus a series of ice rock avalanches on iliamna volcano alaska the 2005 mt steller rock ice avalanche in alaska and ice and rock avalanches at monte rosa italy in 2005 and 2007 deposit volumes range from 10 6 to 10 8 m 3 and include rock ice and snow here we focus on thermal aspects of these failures reflecting the involvement of glacier ice and permafrost at all sites suggesting that thermal perturbations likely contributed to the slope failures we use surface and troposphere air temperatures near surface rock temperatures satellite thermal data and recent 2d and 3d thermal modeling studies to document thermal conditions at the landslide sites we distinguish between thermal perturbations of volcanic geothermal and climatic origin and thermal perturbations related to glacier permafrost interaction the data and analysis support the view that recent current and future climatic change increases the likelihood of large slope failures in steep glacierized and permafrost terrain however some important aspects of these settings such as the geology and tectonic environment remain poorly understood making the identification of future sites of large slope instabilities difficult in view of the potentially large natural disasters that can be caused by such slope failures improved data and understanding are needed

irregular earthquake cycle along the southern tianshan front aksu area china 1 a long deformation record 16 5 ka showing nonsteady earthquake recurrence is established for the aksu thrust tianshan china on the basis of cosmogenic 10be dating of faulted surfaces topographic leveling across the aksu fault scarp indicates up to 10 m uplift across a moraine abandoned 16 5 ka and similar uplift of 6 m across two inset surfaces yielding ages of 12 5 and 5 ka successively smaller uplifts of terraces younger than 5 ka indicate that three or more major earthquakes occurred during this period these data show that the aksu thrust fault was quiet for at least 7500 years and active in the last 5000 years and probably in the interval 16 5 12 5 ka the seismic cycle along the aksu thrust fault over the last 16 500 years was thus strongly irregular showing long quiescence and clustering which is a challenge for paleoseismology and hazard assessment this irregularity also makes it more difficult to estimate long term shortening rates nevertheless we are able to constrain a minimum total shortening rate 7 mm yr across the southern tianshan front for the last 12 500 years that is about a third of the total geodetic rate for the western tianshan 20 mm yr

enhanced rock slope failure following ice sheet deglaciation timing and causes this research was supported by nerc cosmogenic isotope analysis facility grant number 9046 0308

36cl terrestrial cosmogenic nuclide dating suggests late pleistocene to early holocene mass movements on the south face of aconcagua mountain and in the las cuevas horcones valleys central andes argentina

plugs or flood makers the unstable landslide dams of eastern oregon abstract landslides into valley bottoms can affect longitudinal profiles of rivers thereby influencing landscape evolution through base level changes large landslides can hinder river incision by temporarily damming rivers but catastrophic failure of landslide dams may generate large floods that could promote incision dam stability therefore strongly modulates the effects of landslide dams and might be expected to vary among geologic settings here we investigate the morphometry stability and effects on adjacent channel profiles of 17 former and current landslide dams in eastern oregon data on landslide dam dimensions former impoundment size and longitudinal profile form were obtained from digital elevation data constrained by field observations and aerial imagery while evidence for catastrophic dam breaching was assessed in the field the dry primarily extensional terrain of low gradient volcanic tablelands and basins contrasts with the tectonically active mountainous landscapes more commonly associated with large landslides all but one of the eastern oregon landslide dams are ancient likely of order 10 3 to 10 4 years old and all but one has been breached the portions of the oregon landslide dams blocking channels are small relative to the area of their source landslide complexes 0 4 33 6 km 2 the multipronged landslides in eastern oregon produce marginally smaller volume dams but affect much larger channels and impound more water than do landslide dams in mountainous settings as a result at least 14 of the 17 82 large landslide dams in our study area appear to have failed cataclysmically producing large downstream floods now marked by boulder outwash compared to a 40 70 failure rate for landslide dams in steep mountain environments morphometric indices of landslide dam stability calibrated in other environments were applied to the oregon dams threshold values of the blockage and dimensionless blockage indices calibrated to worldwide data sets successfully separate dam sites in eastern oregon that failed catastrophically from those that did not accumulated sediments upstream of about 50 of the dam sites indicate at least short term persistence of landslide dams prior to eventual failure nevertheless only three landslide dam remnants and one extant dam significantly elevate the modern river profile we conclude that eastern oregon s landslide dams are indeed floodmakers but we lack clear evidence that they form lasting plugs

lateglacial rock slope failures in north west ireland age causes and implications nine postglacial quartzite rock slope failures rsfs in north west ireland were dated using cosmogenic 10be weighted mean rsf ages range from 17 7 0 9 to 12 5 0 7 ka or 16 6 0 7 to 11 7 0 5 ka depending on assumed 10be production rate all dated rsfs occurred within 5000 years following ice sheet deglaciation at 17 4ka 16 3 ka and all but two occurred within 2000 years after deglaciation the timing of rsfs rules out glacial debuttressing permafrost degradation and enhanced deglacial cleft water pressures as triggers of failure in most cases we infer that paraglacial stress release and associated fracture propagation were critical in reducing rock masses to critical stability although earthquakes caused by lateglacial glacio isostatic rebound and or release of stored tectonic stresses may have triggered failure in some or all cases in conjunction with data from related studies our results imply that most undated rsfs outside the limit of younger dryas glaciation in the british isles are of lateglacial age and that numerous lateglacial rsfs occurred inside these limits with subsequent removal of debris by glaciers they support the view that paraglacial rsf activity in tectonically stable intraplate terrains was concentrated within a few millennia following deglaciation

epigenetic gorges in fluvial landscapes epigenetic gorges form when channels that have been laterally displaced during episodes of river blockage or aggradation incise down into bedrock spurs or side walls of the former valley rather than excavating unconsolidated fills and reinhabiting the buried paleovalley valley filling events that promote epigenetic gorges can be localized such as a landslide dam or an alluvial debris flow fan deposit at a tributary junction or widespread such as fluvial aggradation in response to climate change or fluctuating base level the formation of epigenetic gorges depends upon the competition between the resistance to transport strength and roughness of valley filling sediments and a river s ability to sculpt and incise bedrock the former affects the location and lateral mobility of a channel incising into valley filling deposits the latter determines rates of bedrock incision should the path of the incising channel intersect with bedrock that is not the paleovalley bottom epigenetic gorge incision by definition post dates the incision that originally cut the valley strath terraces and sculpted bedrock walls that form in relation to epigenetic gorges should not be used to directly infer river incision induced by tectonic activity or climate variability rather they are indicative of the variability of short term bedrock river incision and autogenic dynamics of actively incising fluvial landscapes the rate of bedrock incision associated with an epigenetic gorge can be very high 1 cm yr typically orders of magnitude higher than both short and long term landscape denudation rates in the context of bedrock river incision and landscape evolution epigenetic gorges force rivers to incise more bedrock slowing long term incision and delaying the adjustment of rivers to regional tectonic and climatic forcing copyright 2008 john wiley sons ltd

catastrophic rock slope failures and late quaternary developments in the nanga parbat haramosh massif upper indus basin northern pakistan abstract the nanga parbat haramosh massif has some of the greatest relief on earth and highest measured rates of uplift denudation and river incision in bedrock many studies have sought to understand how its morphology relates to geotectonic evolution and glaciations however few catastrophic rock slope failures had been recognised and many of their impacts had been attributed to other processes recently more than 150 of these landslides have been found within a 100 km radius of nanga parbat 8125 m new discoveries are reported east north and west of nanga parbat along the indus streams most generated long run out rock avalanches that dammed the indus or its tributaries some impounding large lakes they initiated episodes of intermontane sedimentation followed by trenching and removal of sediment valley floor features record a complex interplay of impoundment and sedimentation episodes superimposition of streams in pre landslide valley floors and exhumation of buried features these findings depart from existing reconstructions of quaternary events a number of the rock avalanche deposits were previously misinterpreted as tills or moraine and their associated lacustrine deposits attributed to glacial lakes features up to 1000 m above the indus formerly seen as tectonically raised terraces are depositional features emplaced by landslides or erosion terraces recording the trenching of valley fill in landslide interrupted river reaches unquestionably tectonics and glaciation have been important but decisive and misread formative events of the holocene involve a post glacial landslide fragmented fluvial system the latter has kept valley developments in a chronic state of disequilibrium with respect to climatic and geotectonic controls accepted glacial chronologies are put in doubt particularly the extent and timing of the last major glaciation the pace and role processes in the holocene have been seriously underestimated

bedrock incision rock uplift and threshold hillslopes in the northwestern himalayas the topography of tectonically active mountain ranges reflects a poorly understood competition between bedrock uplift and erosion dating of abandoned river cut surfaces in the northwestern himalayas reveals that the indus river incises through the bedrock at extremely high rates 2 12 mm yr 1 in the surrounding mountains the average angles of hillslopes are steep and essentially independent of erosion rate suggesting control by a common threshold process in this rapidly deforming region an equilibrium is maintained between bedrock uplift and river incision with landsliding allowing hillslopes to adjust efficiently to rapid river down cutting

large rockslides in the southern central andes of chile 32 34 5 s tectonic control and significance for quaternary landscape evolution abstract the distribution and age of large 0 1 km2 pliocene to recent rockslides in the chilean cordillera principal 32 34 5 s the southern central andes has been analyzed to determine the rockslide triggering mechanisms and impact on regional landscape evolution most of the rockslides appear in the western cordillera principal and cluster along major geological structures variographic analyses show spatial correlation between rockslides geological structures and shallow seismicity a relative chronosequence was calibrated with existing 14c and 40ar 39ar dates and new cosmogenic nuclide exposure ages for selected rockslides rockslide induced sediment yield was estimated with empirical relations for rockslide area distributions throughout the quaternary rockslides have delivered sediment to streams at rates equivalent to denudation rates of 0 10 0 06 mm a 1 while estimates using short term 20 a seismicity records are 0 3 0 2 0 6 mm a 1 the estimates of sediment transfer and the spatial distribution of rockslides reflect a landscape in which tectonic and geological controls on denudation are more significant than climate

nature and timing of quaternary glaciation in the himalayan tibetan orogen abstract much effort has been made in recent years to define the timing and extent of quaternary glaciation throughout the himalayan tibetan orogen these studies are challenging because of the logistical and political inaccessibility of the region and the inherent problems associated with the application of numerical dating techniques nevertheless the studies are providing abundant evidence for significant glacial advances throughout the last several glacial cycles and are beginning to accurately define the extent and timing of glaciation in selected regions studies are showing that himalayan tibetan glaciers in arid regions during the last glacial cycle reached their maximum extent early in the cycle and that global last glacial maximum glacier advances were significantly less extensive however along the more monsoonal influenced greater himalaya there is increasing evidence to suggest that glaciation was more extensive later in the last glacial cycle but this has yet to be fully assessed in addition the new studies are showing that throughout most himalayan tibetan regions significant glacier advances occurred during the lateglacial and early holocene with minor advances in some regions during the mid holocene the still relatively poor chronological control in the himalayan tibetan orogen however makes it difficult to construct correlations across the region and with regions elsewhere in the world this in turn makes it hard to assess the relative importance of the different climatic mechanisms that force glaciation across the himalayan tibetan orogen and to quantify paleoclimate change in this high altitude subtropical region the lateglacial and holocene glacial records however are particularly well preserved in several himalayan tibetan regions glacial successions such as these have the greatest potential to be examined in detail using newly developing numerical dating and geomorphic and sedimentologic methods to derive high resolution terrestrial records of glaciation that will help in paleoclimatic reconstruction for high altitude subtropical regions

glacier and landslide feedbacks to topographic relief in the himalayan syntaxes despite longstanding research on the age and formation of the tibetan plateau the controls on the erosional decay of its margins remain controversial pronounced aridity and highly localized rock uplift have traditionally been viewed as limits to the dissection of the plateau by bedrock rivers recently however glacier dynamics and landsliding have been argued to retard headward fluvial erosion into the plateau interior by forming dams and protective alluvial fill here we report a conspicuous clustering of hundreds of natural dams along the indus and the tsangpo rivers where these cross the himalayan syntaxes the indus is riddled by hundreds of dams composed of debris from catastrophic rock avalanches forming the largest concentration of giant landslide dams known worldwide whereas the tsangpo seems devoid of comparable landslide dams in contrast glacial dams such as river blocking moraines in the headwaters of both rivers are limited to where isolated mountain ranges intersect the regional snowline we find that to first order high local topographic relief along both rivers corresponds to conspicuously different knickzones and differences in the type and potential longevity of these dams in both syntaxes glacier and landslide dams act as a negative feedback in response to fluvial dissection of the plateau margins natural damming protects bedrock from river incision and delays headward knickpoint migration thereby helping stabilize the southwestern and southeastern margins of the tibetan plateau in concert with the effects of upstream aridity and localized rock uplift

rock slope failure following late pleistocene deglaciation on tectonically stable mountainous terrain the ages of 31 postglacial rock slope failures rsfs in scotland and nw ireland derived from 89 cosmogenic isotope exposure ages are employed to analyse the temporal pattern of failure and its relationship to the timing of deglaciation rates of glacio isostatic crustal uplift and periods of rapid climate change rsf ages span almost the whole period since ice sheet retreat from 18 2 1 2 ka to 1 7 0 2 ka or from 17 1 1 0 ka to 1 5 0 1 ka depending on the production rate used in 10 be age calculation but catastrophic failure of rock slopes was w4 6 times more frequent prior to w11 7 ka than during the holocene 95 of dated rsfs at sites deglaciated during retreat of the last ice sheet occurred within w5400 years after deglaciation with peak rsf activity 1600e1700 years after deglaciation this time lag is inferred to represent 1 stress release initiated by deglacial unloading leading to 2 time dependent rock mass strength degradation through progressive failure plane development and ultimately 3 to either spontaneous kinematic release or failure triggered by some extrinsic mechanism by contrast 11 dated rsfs at sites reoccupied by glacier ice during the younger dryas stade yds of w12 9e11 7 ka exhibit no clear temporal pattern suggesting that glacial reoccupance during the yds was ineffective in preconditioning a renewed cycle of enhanced rsf activity comparison of timing of individual rsfs with that of deglaciation and rapid warming events at w14 7 ka and w11 7 ka suggests that glacial debuttressing enhanced joint waterpressuresduringdeglaciationandthawofpermafrosticeinrockjointscouldhavetriggeredfailurein only a small number of cases conversely the timing of maximum rsf activity following ice sheet deglaciation corresponds broadly with maximum rates of glacio isostatic crustal uplift suggesting that the two are linked by enhanced seismic activity a seismic failure trigger is consistent with full slope failure at all sites where failure planes are clearly defined our results indicate that numerous rsfs must have occurred in areas that were reoccupied by glacier ice during the yds but have not been identified because runout debris was removed by yds glaciers more generally they provide the first reliably dated body of evidence to support the view that retreat of the last ice sheets in tectonically stable mountainous terrain initiated a period of enhanced rock slope failure due to deglacial unloading and probably lateglacial seismic activity implying that most undated rsfs in such areas are probably of lateglacial or veryearly holocene age they also demonstrate however that a low frequency of rsf activity extended throughout the holocene

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

cooling history of the nw himalaya pakistan fission track and 40ar 39ar cooling ages indicate that the late tertiary cooling history of the himalayan ranges of northern pakistan is largely a function of uplift and erosion interpretation of cooling ages which range from under 0 5 ma to over 80 ma suggests that during the late tertiary long term uplift rates at least doubled from under 0 2 mm yr to in some cases well over 0 5 mm yr uplift rates show strong and systematic regional variations as well which reflect the greater uplift of eastern and northern regions the association of very rapid uplift and erosion with the nanga parbat haramosh massif can be explained by a locally vigorous collision of india with eurasia near a promontory of indian crust the resultant rapid uplift of the nanga parbat haramosh massif reactivated the main mantle thrust melange zone with a reversed sense of motion discontinuities in the coolingage distribution along the main mantle thrust in the southern swat hazara region may be the result of the thermal effects of overthrusting

quaternary moraines vs catastrophic rock avalanches in the karakoram himalaya northern pakistan a history and conception of glacial events for the central karakoram himalaya proposed some 80 years ago by giotto dainelli are largely accepted today however certain deposits identified as terminal moraine complexes marking glacial episodes were actually emplaced by rock avalanches in the skardu and shigar intermontane basins of baltistan at least 15 rock avalanche events were previously mapped as moraine or till criteria used for distinguishing these catastrophic landslide deposits emphasize homogeneous lithology of rubble and matrix clast shape facies characteristics the large scale unity of emplacement and morphological relations to valley topography the deposits of three events at katzarah satpura and the north end of shigar valley have been reconstructed in detail thick supraglacial debris does not result in similar deposits extensive valley fills river terraces large sediment fans and lacustrine sediments formerly attributed to late glacial conditions are reinterpreted as postglacial events involving rock avalanches that interrupted fluvial development existing reconstructions of glaciations are left in doubt especially late glacial events in the central karakoram as are the roles assigned to karakoram main indus valley and western himalayan ice

late quaternary holocene landscape evolution of a monsoon influenced high himalayan valley gori ganga nanda devi ne garhwal the garhwal himalaya provides an excellent natural laboratory in which to examine landscape evolution in a monsoon influenced high mountain environment geomorphic and sedimentological analysis and 10be cosmogenic radionuclide crn surface exposure dating of moraines fans and river and strath terraces in the gori ganga valley of nanda devi ne garhwal indicate that fans and river terraces developed rapidly by debris flow and flood processes during periods of deglaciation these phases of high sediment transfer occurred at 1 2 4 5 and 7 8 ka fan incision rates subsequent to major times of resedimentation after each glacial advance are between 19 and 57 mm year this contrasts with bedrock incision rates based on mid holocene strath terraces of 5 mm year these rates indicate that despite episodes of rapid denudation and resedimentation linked to glacial activity in this region the background rates of denudation are similar to those for other regions of the himalaya averaging several millimeters per year furthermore these data show the importance of climatic controls on landscape evolution and suggest a strong monsoonal control on the dynamics of earth surface processes in this region

cosmogenic age constraints on post lgm catastrophic rock slope failures in the tatra mountains western carpathians textcopyright 2015 elsevier b v although deglaciation is one of the crucial factors controlling the stability of slopes in high mountains the chronological response of rock slope failure rsf to glacier retreat still remains poorly known here we provide the first cosmogenic 10be age constraints on prominent rock avalanches and rockfalls collectively termed rock slope failures rsfs from the tatra mountains the highest mountain range with the most pronounced glacier morphology within the carpathians six representative rsfs were selected for surface exposure dating in the mountain range two sites are situated in the western part with less pronounced local relief and gentler slope gradient and four come from the highest eastern part with oversteepened rock slopes our dataset also contains the largest known rsf in the tatra mountains the koprova rock avalanche with a volume of 5 4 106m3 based on 26 10be dated boulders the weighted mean ages of individual rsf accumulations range between 20 2 1 2 and 10 1 0 3ka our results suggest that smaller structurally predisposed failures mainly rockfalls in the steepest parts of the mountains reacted immediately i e a few hundred years to deglaciation whereas more complex slope deformations in terrain with lower local relief involving the largest rock avalanche in the tatra mountains experienced a substantial time lag i e several millennia in respect to ice retreat in the case of delayed rsfs their origin can be well correlated with warmer and more humid periods in the lateglacial early holocene such as the bolling allerod chronozone and after the onset of the holocene

rock avalanche characteristics in dry climates and the effect of flow into lakes insights from mid tertiary sedimentary breccias near artillery peak arizona rock avalanche deposits can be significant components of aggradational sequences formed in dry climates features distinguishing such deposits from their closest counterparts debris flow deposits reflect the higher energies and shear strengths associated with rock avalanche lobes and their tendency to generate their own matrix through pulverization associated with the failure event evaluation of sedimentary breccias in oligocene miocene strata deposited under dry climatic conditions in west central arizona indicates that many are of rock avalanche origin some are sufficiently large to have represented large rock avalanches that is sturzstroms at the time of emplacement and display features consistent with descriptions of such lobes some rock avalanche deposits interbedded with lacustrine sediments represent initially subaerial lobes that flowed into lakes these bodies locally are intruded by substrate derived injection structures and contaminated by lakebed mud mud contamination was initially concentrated along the bases of lobes but affected a progressively greater proportion of the flows with increasing subaqueous runout contaminated portions of rock avalanche lobes exhibit features consistent with decreased shear strength and thoroughly contaminated lobes appear to have transformed into slow moving slurry like flows that experienced internal cycling of debris

subaqueous rock avalanche deposits exposed by post glacial isostatic rebound innfjorddalen western norway abstract this paper presents a detailed description of deposits and landforms of multiple rock avalanches in western norway one of which fell onto water saturated sediments in innfjorddalen below the former water level deposits of the latter are now exposed on the valley floor due to post glacial isostatic rebound at least three rock avalanches from the same source at grafonnfjellet mountain have occurred during late glacial and post glacial time and their deposits are distributed over an area of 1 44 km 2 in the valley these rock avalanches have volumes of 15 1 10 6 m 3 5 4 10 6 m 3 and 0 3 10 6 m 3 and yielded cosmogenic radionuclide 10 be ages of 14 3 1 4 ka 8 79 0 94 ka and 1 028 0 380 ka respectively the youngest event dates within uncertainty limits to a historic rock avalanche in the year 1611 12 ce the rock avalanches formed a stratified succession of deposits the rock avalanche deposits 1 38 m 2 have lobate forms have frontal rims and parallel ridges extend across the valley floor and up the opposite slope and form dams on the valley floor isolated hills comprised of rock boulders 0 61 km 2 interpreted to be toma hills are disconnected from the main rock avalanche deposits by a 520 m wide zone of deformed valley fill sediments trenches and a ground penetrating radar survey of these deposits indicate large scale deformation or liquefaction numerical runout modeling of the rock avalanches with the code dan3d supports the interpretation of their landforms and sources and highlights their runout behavior

mineral magnetic properties of artificial samples systematically mixed from haematite and magnetite summary detailed rock magnetic investigations were carried out on a set of samples with defined ratios of haematite and magnetite the measured parameters provide a reference for interpreting common rock magnetic parameters in investigations of sediments the contribution of haematite to the magnetic fraction must exceed 95 wt of the magnetic fraction when mixed with magnetite in order to visibly influence grain size and coercitivity indicative magnetic parameters coercivity of remanence bcr and coercive force bc do not change in the same way with increasing haematite content which results in a peak bcr bc value at around 99 5 wt haematite variations in haematite content can be ignored when interpreting most rock magnetic parameters especially grain size indicative parameters for samples where haematite contents range from 0 to 98 wt the s ratio is still the most sensitive parameter for estimating the relative amount of haematite in magnetite haematite mixtures a combination of s ratio the saturation isothermal remanent magnetization divided by the low field magnetic susceptibility sirm lf and bcr is the most effective way to identify haematite in natural samples our results agree with literature data and fill the gap between results obtained either from pure magnetite or haematite with comparable grain sizes

effects of tectonic deformation and landslides in the erosion of a mountain plateau in the transitional zone between the central and patagonian andes

karakorum temperature out of phase with hemispheric trends for the past five centuries a systematic increase in global temperature since the industrial revolution has been attributed to anthropogenic forcing this increase has been especially evident over the himalayas and central asia and is touted as a major contributing factor for glacier mass balance declines across much of this region however glaciers of pakistan s karakorum region have shown no such decline during this time period and in some instances have exhibited slight advance this discrepancy known as the karakorum anomaly has been attributed to unusual amounts of debris covering the region s glaciers the unique seasonality of the region s precipitation and localized cooling resulting from increased cloudiness from monsoonal moisture here we present a tree ring based reconstruction of summer june august temperature from the karakorum of north pakistan that spans nearly five centuries 1523 2007 c e the ring width indices are derived from seven collections six picea smithiana and one pinus gerardiana from middle to upper timberline sites in the northern karakorum valleys of gilgit and hunza at elevations ranging from 2850 to 3300 meters above mean sea level mean elevation 3059 m asl the reconstruction passes all traditional calibration verification schemes and explains 41 of the variance of the nested gilgit astore instrumental station data gilgit 1454 m asl 1951 2009 astore 2167 m asl 1960 2013 importantly our results indicate that karakorum temperature has remained decidedly out of phase with hemispheric temperature trends for at the least the past five centuries highlighting the long term stability of the karakorum anomaly and suggesting that the region s temperature and cloudiness are contributing factors to the anomaly

modelling rock avalanche propagation onto glaciers abstract ice rock avalanches which occur in glacial environments are controlled by the presence of snow and ice in the moving material and by possible propagation onto icy basal surfaces all these factors contribute to enhancing the flow mobility mixing with ice and snow hampers block collisions and favours dense flow behaviour ice melting reduces granular friction by saturation of the basal material and fluidization effects propagating onto glaciers offers a smooth surface with low shear resistance this work is a review of the best documented ice rock avalanches and focuses on evaluating their mobility for hazard analysis purposes by providing a set of calibrated cases the rock avalanches have volumes ranging from 5 10 6 m 3 to 25 10 6 m 3 we replicate these events by using sph and fem numerical methods assuming frictional and voellmy basal rheologies the voellmy rheology best performs at replicating the landslide propagation among the back analyzed cases the frictional coefficient ranges in the interval 0 03 0 1 the turbulent coefficient within 1000 m s 2 2000 m s 2 the bulk basal friction angle ranges within 2 75 and 14 with values inversely related to event volumes forward selection of the basal friction angle based on event volume allows the replication of the mount cook ice rock avalanche predicting a maximum runout which is less than 4 larger than observed in the perspective of forward modelling large uncertainty is related to the reconstruction of the post event topographies particularly for the sliding surface mixing with ice and snow reduces basal friction proportionally to ice and snow content pure ice has a basal friction which is reduced by about 75 than basal friction of pure rock melting of ice during rock avalanche propagation has been evaluated for the sherman event the frictional heat generated at the glacier surface results in the melting of 86 2 5 9 kg m 2 which could have contributed to a minimum 20 35 10 reduction of the material friction angle through the sole pore pressure generation within a 40 and 20 cm thick shear layer respectively the largest uncertainty is related to the area of contact between rock and ice

evolution of lakes created by landslide dams and the role of dam erosion a case study of the jiajun landslide on the dadu river china abstract during the late pleistocene strong erosional riverine environments led to the widespread occurrence of landslides along the river valleys in southwestern china such landslides along the middle reaches of the dadu river often caused large scale dammed lakes in this study the typical large scale jiajun landslide and its associated dammed lake were investigated the relatively complete sedimentary sequence of the lake was examined and multi depositional characteristics were found analysis of the history of the dammed lake revealed the relationship between its formation and the river valley erosion the evolution of the dammed lake was reconstructed based on changes of the sedimentary environments we concluded that the lake experienced two stages of high lake level stable lacustrine sedimentation during this period a two stage large scale dam breach and retention periods lasting more than 100 years the relationship between the formation of the ancient barrier lake and the river valley erosion in the middle reaches of the dadu river is indicative of the erosive and depositional environments the evolution of the ancient dammed river landslide valley had considerable effect on valley erosion and the sedimentary environment of the dadu river

reconsidering himalayan river anticlines the observation that major himalayan rivers flow parallel to and down the axis of anticlines oriented transverse to the primary structural grain of the range has puzzled geomorphologists for decades although there is a general consensus that the courses of trans himalayan rivers predate the himalayan orogeny the close association of rivers and structural highs would not be expected to result from the superposition of rivers onto pre existing structures moreover in the past several decades structural studies have shown that the development of river anticlines represents the most recent phase of deformation in the range it is proposed that himalayan river anticlines are the consequence of focused rock uplift in response to significant differences between net erosion along major rivers and surrounding regions this hypothesis is supported by large gradients in observed and predicted erosion rates across major himalayan rivers and by results from an isostasy driven model which requires relatively low flexural rigidities to match the wavelength of himalayan river anticlines whether the amplitude of these structures is due to isostasy or also reflects active crustal channeling is not well constrained but given the uncertainty in the flexural rigidity and in the local and far field erosion rates both possibilities remain viable explanations given the observed correlation between the arun river anticline and local rainfall maxima it is proposed that himalayan river anticlines are the expression of a relatively fine scale linkage between tectonics erosion and climate superimposed on the broader and older canvas of the himalayan orogeny finally it is suggested that the development of river anticlines represents one example along a continuum of features arising from different degrees of erosion structure coupling in active orogens

quaternary glacial history of the central karakoram abstract the quaternary glacial history of the world s highest mountains the central karakoram is examined for the first time using geomorphic mapping of landforms and sediments and 10 be terrestrial cosmogenic nuclide surface exposure dating of boulders on the moraines and glacially eroded surfaces four glacial stages are defined the bunthang glacial stage 0 7 ma the skardu glacial stage marine oxygen isotope stage mis 6 or older the mungo glacial stage mis 2 and the askole glacial stage holocene glaciers advanced several times during each glacial stage these advances are not well defined for the oldest glacial stages but during the mungo and askole glacial stages glacial advances likely occurred at 16 11 13 5 and 0 8 ka the extent of glaciation in this region became increasingly more restricted over time in the braldu and shigar valleys glaciers advanced 150 km during the bunthang and skardu glacial stages while glaciers advanced 80 km beyond their present positions during the mungo glacial stage in contrast glaciers advanced a few kilometers from present ice margins during the askole glacial stage glacier in this region likely respond in a complex fashion to the same forcing that causes changes in northern hemisphere oceans and ice sheets teleconnected via the mid latitude westerlies and also to changes in monsoonal intensity

giant landslides topography and erosion abstract distributions of slope angles in tectonically active mountain belts point to the development of threshold conditions where hillslopes attain a critical inclination or height at which they fail readily because of limitations in material strength it has been proposed that hillslopes adjust to rapid uplift and bedrock incision through an increase in the rate of relief limiting landsliding rather than gradual slope steepening here we test this concept by investigating the relationship between mean local relief h which we take to be a proxy of long term erosion rates e and the occurrence of over 300 of the largest v 10 8 m 3 terrestrial landslides on earth we find that nearly two thirds of these giant landslides have occurred in the steepest 5 of the earth s land surface where relief is close to its proposed upper strength limit they are primarily located in deeply incised valleys along fault bounded fringes of active mountain belts and in volcanic arcs this distribution coincides with areas of high long term erosion rates 4 mm yr 1 confirming that giant landslides contribute to rapid denudation of mountains most of the eroded volume is concentrated in the smallest but steepest parts of mountain belts and volcanic arcs first order estimates of minimum erosion rates accomplished by the largest landslides are 0 01 mm yr 1 these rates are between 1 and 10 of the late pleistocene to holocene mean erosion rates in a given area importantly the landslide erosion rates show a nonlinear increase with mean local relief suggesting that the contribution of giant landslides in total and per event increases significantly with increasing overall erosion rates however giant landslides also occur in areas of lower than average relief h 300 700 m irrespective of whether threshold hillslopes have developed or not factors contributing to these failures include soft rocks extensive low angle discontinuities high rates of fluvial bedrock incision and tectonically driven deformation and slope loading

holocene monsoonal dynamics and fluvial terrace formation in the northwest himalaya india aluminum 26 and beryllium 10 surface exposure dating on cut and fill river terrace surfaces from the lower sutlej valley northwest himalaya documents the close link between indian summer monsoon ism oscillations and intervals of enhanced fluvial incision during the early holocene ism optimum precipitation was enhanced and reached far into the internal parts of the orogen the amplified sediment flux from these usually dry but glaciated areas caused alluviation of downstream valleys up to 120 m above present grade at ca 9 9 k y b p terrace formation i e incision in the coarse deposits occurred during century long weak ism phases that resulted in reduced moisture availability and most likely in lower sediment flux here we suggest that the lower sediment flux during weak ism phases allowed rivers to incise episodically into the alluvial fill

the benner pass rock avalanche cluster suggests a close relation between long term slope deformation dsgsds and translational rock slides and catastrophic failure abstract in mountain ranges deep seated gravitational slope deformations dsgsds and extremely rapid mass wastings of rock 105 m3 in volume catastrophic rock slope failures crf are present yet their mutual relation is poorly documented near the brenner pass 1370 m asl in the eastern alps five catastrophic rock slope failures of medium to high grade metamorphites are clustered brenner pass cluster bpc and three of them are related to dsgsds the catastrophic rock slope failures involved volumes from 12 to 110 mm3 and show fahrboeschung angles of 10 27 numerical dating 14c 234u 230th suggests that all catastrophic slope failures of the bpc occurred between 13 5 and 6 2 ka three of the crf events may have occurred during the younger dryas 12 7 11 7 ka whereas two events occurred during the holocene backwater basins dammed up by the crfs range from 2 5 km2 ridnaun rock avalanche to 15 5 km2 stilfes rock avalanche three of the catastrophic rock slope failures are associated with and developed as a partial failure of a dsgsd this suggests that progressively slow deformation of slopes ultimately exceeded a stability threshold resulting in catastrophic rock slope failures the initial kinematic mechanisms of failure vary between large scale toppling wedge sliding and planar sliding and are strongly controlled by the structural setting of the slopes a direct connection of catastrophic mass wasting with specific palaeoclimatic conditions e g phases of enhanced precipitation is not indicated however this does not exclude specific meteorological situations e g occurrence of short term heavy rainfall that may have expedited slope instability and perhaps even triggered catastrophic events attempts to correlate catastrophic rock slope failures with specific palaeoclimatic regimes are still encumbered by substantial methodical uncertainties and imprecisions as well as the scarcity of dated crf events the mapped distribution of crfs unequivocally indicates that structural predisposition is the most significant long term control in forming crf clusters

catastrophic landslides and their effects on the upper indus streams karakoram himalaya northern pakistan abstract the paper examines the nature and geomorphic influences of deposits from rock avalanches that obstruct rivers most of the 115 rockslide rock avalanche events identified in the karakoram himalaya straddled one or more stream valleys at least 73 of these landslides formerly dammed the indus or its tributaries upstream of the barriers remnants exist of once very extensive lacustrine deposits the stability and long term survival of dams from large rock avalanches is addressed and the reasons for the gradual or phased rather than catastrophic and sudden breaching case histories emphasise the erosional and depositional forms associated with the barriers they are reconstructed in terms of the emplacement and properties of the deposits from rock avalanches and the response of the river to interruption by them these barriers have exerted a substantial control over stream response and development for most of the holocene at least today they are associated with distinctive features of channel form and thalweg river terrace systems intermontane sediment sinks and sources and local erosional forms in bedrock more broadly the landslide barriers have created a naturally fragmented river system deposition and erosion in the lower few tens or hundreds of meters of the upper indus stream valleys have been dominated by epicycles of aggradation trenching and downcutting that mainly reflect the scale timing and history of each barrier the landforms involved are only indirectly related to the late glacial and paraglacial conditions that have hitherto been regarded as the main explanation

mass movement in the himalaya new insights and research directions abstract ongoing studies that relate tectonics to the processes at the surface of earth show that many more sources of information about agents of shallow denudation such as mass movement are required to comprehend the long term erosion that leads to deep denudation over geologic time mass movement in the himalaya is scale dependent from the massive extension of whole mountain ranges gravity tectonics through the sackung failure of single peaks to the smallest slope failures generally denudation of the himalayan orogen begins with slope failure onto glaciers and into river valleys and continues by glacial and fluvial transport the maximum size of stable slopes and mean angles of slope that are produced by these failures are complex and controlled by a variety of factors including mass strength of the rocks stress fields angles of internal friction controlled by rock type cohesion that includes the control of rock temperature bulk unit weight of rock and discontinuities the processes of mass movement in the himalaya have been described many times for the past two centuries recently developments in a variety of fields have been introduced to assess the character of mass movement geomorphometry remote sensing digital elevation models and geographic information system technology are revolutionizing the study of mass movement in the himalaya

timing and features of a late mis 2 rock avalanche in the eastern himalayas constrained by 10be exposure dating abstract we investigate a previously unrecorded rock avalanche deposit yadong rock avalanche that resulted from a major mountain slope failure on the northwest slopes of mt chomo lhari in the eastern himalayas we provide detailed mapping of the yadong rock avalanche and date the rock avalanche using 10be surface exposure dating the 10be exposure ages of six samples suggest that the yadong rock avalanche occurred between 14 2 1 3 13 1 1 3 ka during the bolling allerod ba period the climate was semi arid during the ba period as it is today which suggests that precipitation was unlikely the trigger for this rock avalanche the relatively small paleo glaciers make glacial debuttressing trigger unlikely since the rock scar is situated above the lower permafrost limit degradation of permafrost associated with deglaciation was also unlikely to be the trigger given the rock avalanche is located near the yadong fault which is part of the active yadong gulu rift and the yadong gulu rift has experienced great earthquakes on centennial to millennial timescales we suggest that the most probable trigger for this rock avalanche was a seismic event associated with the yadong fault the result provides evidence for identifying a paleo seismic event occurred during 14 2 1 3 13 1 1 3 ka these findings have important implications for understanding the mechanisms for driving rock avalanches and associated landscape evolution across the himalayas as well as for extending the limited scientifically documented records of major mass movements in the eastern himalayan region

post glacial rock avalanches in the obersee valley glarner alps switzerland abstract the geological record of prehistoric rock avalanches provides invaluable data for assessing the hazard posed by these rare but destructive mass movements here we investigate two large rock avalanches in the obersee valley of the glarner alps switzerland providing detailed mapping of landslide and related quaternary phenomena revised volume estimates for each event and surface exposure dating of rock avalanche deposits the rautispitz rock avalanche originated from the southern flank of the obersee valley releasing approximately 91 million m 3 of limestone on steeply dipping bedding planes debris had maximum horizontal travel distance of 5000 m a fahrboeschung angle relating fall height to length of 18 and was responsible for the creation of lake obersee deposits are more than 130 m thick in places the platten rock avalanche encompassed a source volume of 11 million m 3 sliding from the northern flank of the obersee valley on similar steeply dipping limestone beds bedrock forms a syncline under the valley debris had a maximum horizontal travel distance of 1600 m with a fahrboeschung angle of 21 and is more than 80 m thick in places deposits of the platten rock avalanche are superposed atop those from the rautispitz event at the end of the obersee valley where they dam lake haslensee runout for both events was simulated using the dynamic analysis code dan3d results showed excellent match to mapped deposit extents and thickness and helped confirm the hypothesized single event failure scenarios 36 cl cosmogenic nuclide surface exposure dating of 13 deposited boulders revealed a younger dryas age of 12 6 1 0 ka for the rautispitz rock avalanche and a mid holocene age of 6 1 0 8 ka for the platten rock avalanche a seismological trigger is proposed for the former event due to potentially correlated turbidite deposits in nearby lake zurich

bedload to suspended load ratio and rapid bedrock incision from himalayan landslide dam lake record about 5400 cal yr bp a large landslide formed a n400 m tall dam in the upper marsyandi river central nepal the resulting lacustrine and deltaic deposits stretched n7 km upstream reaching a thickness of 120 m 14 c dating of 7 wood fragments reveals that the aggradation and subsequent incision occurred remarkably quickly 500 yr reconstructed volumes of lacustrine 0 16 km 3 and deltaic 0 09 km 3 deposits indicate a bedload to suspended load ratio of 1 2 considerably higher than the 1 10 that is commonly assumed at the downstream end of the landslide dam the river incised a new channel through 70 m of greater himalayan gneiss requiring a minimum bedrock incision rate of 13 mm yr over last 5400 yr the majority of incision presumably occurred over a fraction of this time suggesting much higher rates the high bedload ratio from such an energetic mountain river is a particularly significant addition to our knowledge of sediment flux in orogenic environments 2007 university of washington all rights reserved

nature and timing of large landslides within an active orogen eastern pamir china abstract large scale landsliding involving 106 m3 in volume is important in landscape development in high mountains to assess the importance of large landslides in high mountains four large landslides bulunkou muztagh taheman and yimake were mapped in the ne chinese pamir at the westernmost end of the himalayan tibetan orogen and dated using 10be terrestrial cosmogenic nuclides the bulunkou landslide at the southernmost end of muji valley is composed of 1 7 107 m3 of landslide debris and has an age of 2 0 0 1 ka the muztagh landslide located on the sw side of the massif muztagh ata is composed of 4 7 108 m3 of debris and has an age of 14 3 0 8 ka the taheman landslide located south of muztagh ata is composed of 2 6 108 m3 of landslide debris and has an age of 6 8 0 2 ka the yimake landslide on the northern frontal range of the pamir at the southwestern end of the tarim basin is composed of 1 4 109 m3 of landslide debris and has an age of 7 1 0 6 ka two other large landslides are present in the region the aerpa aigezi on a tributary of the gez river and the bile jiyi on the yarkand river landslides and are composed of 1 6 107 m3 and 5 2 106 m3 of landslide debris respectively however the aerpa aigezi and bile jiyi landslides were not studied in as much detail or dated because of their inaccessibility given the tectonically active nature of this region with numerous active faults and the morphology of the landslides these landslides were likely triggered by earthquakes however other causes including long term increased precipitation and geologic bedrock structure could be important contributing factors in their formation

role of river incision in enhancing deformation many active compressional belts contain examples of transverse rivers intersecting anticlines at their highest structural and topographic position this unusual association between rivers and doubly plunging anticlines at relatively small scales is usually explained by some form of antecedence or superposition in this article i suggest an alternative explanation i e that river erosion unloads the crust and that this process causes local deformation to be enhanced in the vicinity of rivers i show the plausibility of this hypothesis with the aid of a coupled three dimensional mechanical surface process mathematical model the conclusion is that river incision can have a major influence on deformation of the surrounding crust if incision occurs at the same time that the crust is deforming plastically in response to regional compression in this case incision amplifies background deformation at a relatively small scale leading to the formation of noncylindrical folds with culminations coinciding with river incision in the absence of regional deformation the response of the crust to river incision is small and of long wavelength because it is governed by flexural isostasy of relatively rigid elastic crust thus whether rivers exert an influence on local deformation depends critically on the timing between river incision and regional deformation this point may explain why in some cases rivers appear to have had no significant influence on local deformation whereas in other cases they have

the evolution 2010 2015 and engineering mitigation of a rockslide dammed lake hunza river pakistan characterisation by analytical remote sensing abstract the remnants of rockslide dams are widespread in the deeply incised river valleys of the northwest himalayas and adjacent pamir mountains of central asia in january 2010 a major rockslide estimated volume 55 mm3 dammed the hunza river nw pakistan and a rockslide dammed lake lake gojal immediately began to form the lake overtopped the rockslide dam 145 days later through a spillway excavated in the surface of the debris by pakistan authorities lake gojal successively reduced in volume in response to spillway widening and deepening in engineering works up to may 2013 on august 28 2015 day 2063 of impoundment a remnant lake still remains using srtm 3 arc second digital terrain data and ten high resolution satellite images from the period march 2010 august 2015 we document the river damming environment of the attabad rockslide track and quantify the development of rockslide dammed lake gojal and calculate lake areas and volumes at various stages of filling stable overtopping and partial draining to a final stable configuration we introduce a method of delimiting lake shorelines by a pixel method which produces a mean elevation surface in the srtm dem this technique results in accurate estimates of shoreline elevation and corresponding lake areas and volumes we estimate the maximum volume reached by lake gojal 51 days after overtopping to have been approximately 455 mm3 using this data we also evaluate the mitigation works carried out by pakistan authorities and find that i they achieved an initial reduction of about 26 in the maximum possible volume of lake gojal that would have been reached without engineering intervention and ii as of august 28 2015 in drawing down the lake by 40 m they had achieved a 72 reduction in the maximum volume reached by lake gojal after overtopping without a catastrophic release taking place the emplacement of rockslide dams and the behaviour of their impounded lakes are critical hazards to communities and the development of infrastructure including hydroelectric facilities in this region of central asia we show that a combination of high resolution optical satellite imagery and srtm 3 arc second digital topography is very effective in producing key first order data on rockslide dammed lakes for geomorphic and hydrological analysis as well as the evaluation of engineering mitigation

large landslides lie low excess topography in the himalaya karakoram ranges mass wasting is an important process for denuding hillslopes and lowering ridge crests in active mountain belts such as the himalaya karakoram ranges hkr such a high relief landscape is likely to be at its mechanical threshold maintained by competing rapid rock uplift river incision and pervasive slope failure we introduce excess topography z e for quantifying potentially unstable rock mass volumes inclined at angles greater than a specified threshold angle we find that z e peaks along major fluvial and glacial inner gorges which is also where the majority of 492 large 0 1 km 2 rock slope failures occur in the himalaya9s largest cluster of documented pleistocene to holocene bedrock landslides our data reveal that bedrock landslides in the hkr chiefly detached from near or below the median elevation whereas glaciers and rock glaciers occupy higher elevation bands almost exclusively less than 10 of the area of the hkr is upslope of glaciers such that possible censoring of evidence of large bedrock landslides above the permanent snow line barely affects this finding bedrock landslides appear to preferentially undermine topographic relief in response to fluvial and glacial incision along inner gorges unless more frequent and smaller undetected failures or rigorous peri glacial erosion compensate for this role at higher elevation either way the distinct patterns of excess topography and large bedrock landsliding in the hkr juxtapose two stacked domains of landslide and peri glacial erosion that may respond to different time scales of perturbation our findings call for more detailed analysis of vertical erosional domains and their geomorphic coupling in active mountain belts

millennial lag times in the himalayan sediment routing system abstract any understanding of sediment routing from mountain belts to their forelands and offshore sinks remains incomplete without estimates of intermediate storage that decisively buffers sediment yields from erosion rates attenuates water and sediment fluxes and protects underlying bedrock from incision we quantify for the first time the sediment stored in 38 000 mainly postglacial himalayan valley fills based on an empirical volume area scaling of valley fill outlines automatically extracted from digital topographic data the estimated total volume of 690 242 452 km 3 is mostly contained in few large valley fills 1 km 3 while catastrophic mass wasting adds another 177 31 km 3 sediment storage volumes are highly disparate along the strike of the orogen much of the himalaya s stock of sediment is sequestered in glacially scoured valleys that provide accommodation space for 44 of the total volume upstream of the rapidly exhuming and incising syntaxes conversely the step like long wave topography of the central himalayas limits glacier extent and thus any significant glacier derived storage of sediment away from tectonic basins we show that exclusive removal of himalayan valley fills could nourish contemporary sediment flux from the indus and brahmaputra basins for 1 kyr though individual fills may attain residence times of 100 kyr these millennial lag times in the himalayan sediment routing system may sufficiently buffer signals of short term seismic as well as climatic disturbances thus complicating simple correlation and interpretation of sedimentary archives from the himalayan orogen its foreland and its submarine fan systems