rock avalanche geomorphological and hydrological impact on an alpine watershed abstract rock avalanches are large flow like movements of fragmented rock that can cause extensive and rapid topographic changes for which very few quantitative data are available this paper analyses the geomorphological and hydrological impact of the 3 million m 3 thurwieser rock avalanche 2004 italian central alps by using terrestrial laser scanner airborne lidar and gnss data collected from 2005 to 2014 sediment yield with respect to the normal valley regime the dynamic and mass balance of affected glaciers and the reorganization of superficial and groundwater flow networks are quantified in the middle portion of the avalanche deposit a natural sediment trap collected sediments from a new stream channel developed along the upper portion of the deposit and from a lateral drainage basin this made possible to assess the 10 year impact of the rock avalanche on the sediment yield which increased from about 120 to about 400 t km 2 a 1 the rock avalanche partially covered a glacier with a shallow debris layer that acted as a thermal insulator limiting ice ablation and producing a 10 m high scarp between the free surface of the glacier and the debris covered portion a reduction of 75 of ice ablation was observed due to thermal insulation the rock avalanche filled a tributary valley splitting the original drainage basin in two under ordinary flows seepage occurs within the avalanche deposit along the old valley axis during high flow conditions a new stream channel is activated along the middle and lower margin of the deposit which has produced a new alluvial fan on the main valley floor the fan evolution is described up to the present volume of about 2000 m 3

comparison of geodetic and glaciological mass balance techniques gulkana glacier alaska u s a the net mass balance on gulkana glacier alaska u s a has been measured since 1966 by the glaciological method in which seasonal balances are measured at three index sites and extrapolated over large areas of the glacier systematic errors can accumulate linearly with time in this method therefore the geodetic balance in which errors are less time dependent was calculated for comparison with the glaciological method digital elevation models of the glacier in 1974 1993 and 1999 were prepared using aerial photographs and geodetic balances were computed giving 6 0 0 7 m w e from 1974 to 1993 and 11 8 0 7 m w e from 1974 to 1999 these balances are compared with the glaciological balances over the same intervals which were 5 8 0 9 and 11 2 1 0 m w e respectively both balances show that the thinning rate tripled in the 1990s these cumulative balances differ by 6 for this close agreement the glaciologically measured mass balance of gulkana glacier must be largely free of systematic errors and be based on a time variable area altitude distribution and the photography used in the geodetic method must have enough contrast to enable accurate photogrammetry

the response of black rapids glacier alaska to the denali earthquake rock avalanches 1 we describe the impact of three simultaneous earthquake triggered rock avalanches on the dynamics of black rapids glacier alaska by using spaceborne radar imagery and numerical modeling we determined the velocities of the glacier before and after landslide deposition in 2002 by using a combination of ers 1 ers 2 tandem radarsat 1 and alos palsar synthetic aperture radar data ice velocity above the debris covered area of the glacier increased up to 14 after the earthquake but then decreased 20 by 2005 within the area of the debris sheets mean glacier surface velocity increased 44 within 2 years of the landslides at the downglacier end of the lowest landslide where strong differential ablation produced a steep ice cliff velocities increased by 109 over the same period by 2007 ice velocity throughout the debris area had become more uniform consistent with a constant ice flux resulting from drastically reduced ablation at the base of the debris without further analysis we cannot prove that these changes resulted from the landslides because black rapids glacier displays large seasonal and interannual variations in velocity however a full stokes numerical ice flow model of a simplified glacier geometry produced a reversal of the velocity gradient from compressional to extensional flow after 5 years which supports our interpretation that the recent changes in the velocity field of the glacier are related to landslide induced mass balance changes

form facies and depositional history of the north long john rock avalanche owens valley california the prehistoric but geomorphically pristine north long john rock avalanche of the inyo mountains piedmont california formed by the catastrophic collapse and disintegration of a 500 1000 m range front bedrock slab this failure rapidly produced and transferred 25 million cubic metres of new sediment to the piedmont where it was deposited in a trough between two coalesced alluvial fans the avalanche consists of nearly monolithologic aplitic unstratified very angular muddy cobble pebble gravel with boulders concentrated at the top and outer margins the deposits are clast supported except in the lower central zone coarse clasts exhibit crackle breccia fabric and the voluminous equant pebbles are the disaggregated products of these clasts the avalanche deposits are distributed in a u shaped body with paired lateral levees 10 60 m high that extend 1560 m from the range front to a 108 m high distal snout each levee contains three segments that along with the snout overlap and extend progress

dynamics of the 1984 rock avalanche and associated distal debris flow on mount cayley british columbia canada implications for landslide hazard assessment on dissected volcanoes abstract in 1984 a mass of quaternary pyroclastic rock est vol 0 74 106m3 slid from the western flank of mount cayley volcano in southwest british columbia the disintegrating rock mass entrained a further 0 20 106 m3 and formed a rock avalanche that travelled a horizontal distance of 3 46 km from its source over a vertical elevation difference of 1 18 km equivalent to a fahrboschung of 19 from the superelevation of the debris trimline in the mid path it is estimated that velocities reached at least 42 m s in the upper part of its path velocities may have approached 70 m s the rock avalanche was partially transformed into a distal debris flow that travelled a further 2 6 km down turbid creek in a narrow channelised path to the squamish river temporarily blocking it the motion of the rock avalanche including the production of a distal debris flow was successfully simulated using a dynamic analytical model both the results of this analysis and field evidence indicate that the rock avalanche did not come to a halt in the upper part of its path as suggested by cruden and lu 1992 but travelled to its distal limit in one uninterrupted movement this finding has important implications for landslide hazard assessment at mount cayley and similar sites the landslide is typical of those which occur on the steep slopes of dissected volcanoes and is one of seven high velocity rock avalanches that have occurred in the garibaldi volcanic belt of southwest british columbia since 1855

late holocene activity of sherman and sheridan glaciers prince william sound alaska abstract two adjacent glaciers in the chugach mountains of south central alaska have markedly different histories on decadal to perhaps centennial timescales sheridan glacier has advanced and retreated hundreds of metres during the latest holocene its recent fluctuations have markedly altered local base level of sherman river which drains sherman glacier and flows into sheridan lake sheridan glacier advanced to its greatest extent during the little ice age raising base level of sherman river and inducing aggradation there of up to 17 m of sediment retreat of sheridan glacier formed a series of lakes that have coalesced as lower lake outlets have become available base level of sherman river has dropped resulting in the evacuation of substantial volumes of sediment from sherman river valley in about 2000 the terminus of sheridan glacier began to disintegrate retreat accelerated dramatically in 2010 by 2016 the glacier had retreated an average of 600 m from its 2010 terminus although some areas retreated up to 1 9 km and others did not retreat at all meanwhile sherman glacier continued a slow advance initiated by a rock avalanche that blanketed much of its ablation area in the 1964 alaska earthquake

geomorphology and weathering characteristics of erratic boulder trains on tierra del fuego southernmost south america implications for dating of glacial deposits abstract erratic boulder trains ebts are a useful glacial geomorphological feature because they reveal former ice flow trajectories and can be targeted for cosmogenic nuclide exposure dating however understanding how they are transported and deposited is important because this has implications for palaeoglaciological reconstructions and the pre exposure and or erosion of the boulders in this study we review previous work on ebts which indicates that they may form subglacially or supraglacially but that large angular boulders transported long distances generally reflect supraglacial transport we then report detailed observations of ebts from tierra del fuego southernmost south america where their characteristics provide a useful framework for the interpretation of previously published cosmogenic nuclide exposure dates we present the first comprehensive map of the ebts and analyse their spatial distribution size and physical appearance results suggest that they were produced by one or more supraglacial rock avalanches in the cordillera darwin and were then transported supraglacially for 100 s of kilometres before being deposited rock surface weathering analysis shows no significant difference in the weathering characteristics of a sequence of ebts previously hypothesized to be of significantly different age i e different glacial cycles we interpret this to indicate that the ebts are much closer in age than previous work has implied this emphasises the importance of understanding ebt formation when using them for cosmogenic nuclide exposure dating

topographic reflection of the socompa debris avalanche chile one of the most remarkable features of the exceptionally well preserved 26 km3 socompa debris avalanche deposit is the evidence for topographically driven secondary flow the avalanche formed by sector collapse of socompa stratovolcano and spread 40 km across a pre existing basin forming a sheet of 50 m average thickness as the avalanche impinged on the western and northern margins of the basin it was reflected back forming a secondary flow that continued to travel 15 km down a gentle slope at an oblique angle to the primary flow the front of the return wave being preserved frozen on the surface of the deposit as a prominent escarpment satellite images aerial photos digital elevation models and field observations were used to reconstruct the sequence of events during avalanche emplacement and in particular during secondary flow the avalanche sheet was divided into distinct terrane groups each believed to have experienced a particular strain history during emplacement evidence for avalanche reflection includes clearly recognizable secondary slide masses sub parallel sets of curvilinear shear zones headwall scarps separating the primary levee from the secondary terranes extensional jigsaw breakup of surface lithologies during return flow and cross cutting or deflection of primary flow fabrics by secondary terranes reflection off the basin margin took place in an essentially continuous manner most major return motions being simultaneous with or shortly following primary flow the secondary flow occurred as a wave that swept obliquely across the primary avalanche direction remobilizing the primary material which was first compressed then stretched as it passed over and rearward of the wave front as return flow occurred surface lithologies were rifted in a brittle manner and the slabs were sheared pervasively as they glided and rotated back into the basin some sank into the more fluidal interior of the avalanche which drained out into a prominent distal lobe extension by factors of up to 1 8 took place during return flow secondary flow took place on slopes of only a few degrees and the distal lobe flowed 8 km on a slope of 1 overall the avalanche is inferred to have slid into place as a fast moving sheet of fragmental rock debris with a leading edge and crust with near normal friction and an almost frictionless fluidal interior and base the avalanche emplacement history deduced from field evidence is consistent with the results of a previously published numerical model of the socompa avalanche

more surprises from the moon volcanic deposits on the moon are almost entirely composed of basaltic lava flows that make up the dark and extensive mare plains high resolution images and compositional data now reveal rare non mare volcanism on the moon s farside

testing landslide and atmospheric effects models for the formation of double layered ejecta craters on mars double layered ejecta dle craters are distinctive among the variety of crater morphologies observed on mars but the mechanism by which they form remains under debate we assess two ejecta emplacement mechanisms 1 atmospheric effects from ejecta curtain induced vortices or a base surge and 2 ballistic emplacement followed by a landslide of ejecta assisted by either surface or pore ice we conduct a morphological analysis of the ejecta facies for three dle craters which impacted into irregular pre existing topography we find that the unique topographic environments affected the formation of grooves and the inner facies and thus appear to be inconsistent with an atmospheric effects origin but are supportive of the landslide hypothesis we distinguish between the two landslide models lubrication by either surface or pore ice by assessing relationships between dle crater ejecta and morphologic features indicative of buried ice deposits including sublimation pits ring mold craters expanded secondary craters and excess ejecta craters the association of dle craters with these features suggests that surface ice was present at the time of the impacts that formed the dle craters we also compare the froude numbers of dle crater ejecta to landslides and find that the ejecta of dle craters are kinematically and frictionally similar to terrestrial landslides that overran glaciers this suggests that the grooves on dle craters may plausibly form through the same shear splitting mechanism as the landslides in summary our analysis supports the hypothesis that dle craters form through meteoroid impacts into decameters thick surface ice deposits emplaced during periods of higher obliquity followed by ejecta sliding on the ice

insights into the kinematics and dynamics of the luanshibao rock avalanche tibetan plateau china based on its complex surface landforms abstract complex topographic features on the surfaces of rock avalanche deposits have been regarded as important indicators for understanding avalanche kinematics and dynamics based on a combination of remote sensing data and in situ observations of surface landforms including toreva blocks transverse and longitudinal ridges ridges separated by conjugate troughs and hummocks a giant holocene rock avalanche on the tibetan plateau is recognized this work aims to understand the kinematics of this event in planview the tongue shaped rock avalanche exhibits a clear sequential distribution of various landforms the translation zone ii is characterised by toreva blocks originating from extension in subzone iii 1 of the accumulation zone iii compression related transverse ridges are well developed longitudinal ridges resulting from lateral velocity differences due to radial spreading are present in the front part of subzone iii 1 farther down ridges separated by conjugate troughs generated by a combination of compression and radial spreading are common in subzone iii 2 subzone iii 3 is characterised by abundant scattered hummocks with circular to oval shapes based on the distributions of these landforms this rock avalanche is proposed to have mainly experienced a motion featuring laminar flow with radial spreading in its distal and marginal parts during transport three distinct processes appear to have occurred in the avalanche mass from the proximal to the distal zones extension dominated sliding in zone ii compression dominated sliding in subzones iii 1 and iii 2 and rapid radial spreading in subzone iii 3

longitudinal ridges in mass movement deposits prominent longitudinal features are often reported on the surfaces of mass movement deposits however the genesis and implications of these have not hitherto been considered and herein we present preliminary observations of their occurrence both in the field and in the laboratory elongated ridges are often oriented sub parallel to the flow direction and aligned radially from the source due to debris spreading they are particularly prominent in large 106m3 rock avalanches emplaced onto deformable substrates and are also found in the proximal reaches of volcanic debris avalanches flowbands which are longer and thinner expressions of longitudinal ridges are continuous along the entire flow length and are observed in rock avalanches emplaced onto glaciers in snow and some ice avalanches in pyroclastic flows and some block and ash flows in ejecta sheets in extraterrestrial landslides and in some volcanic debris avalanches other volcanic debris avalanches and the distal areas of rock avalanches often display hummocks that are aligned radially from the source we propose that these aligned hummocks are remnants of longitudinal ridges the formation of elongate ridges and their expressions as flowbands aligned hummocks or distal lobes and digits in qualitatively similar fashion in both laboratory and field environments suggests they represent an intrinsic tendency of granular flows in a wide range of situations

the alpine mountain plain circulation airborne doppler lidar measurements and numerical simulations on summer days radiative heating of the alps produces rising air above the mountains and a resulting inflow of air from the foreland this leads to a horizontal transport of air from the foreland to the alps and a vertical transport from the boundary layer into the free troposphere above the mountains the structure and the transports of this mountain plain circulation in southern germany alpine pumping were investigated using an airborne 2 m scanning doppler lidar a wind temperature radar dropsondes rawinsondes and numerical models the measurements were part of the vertical transport and orography vertikator campaign in summer 2002 comparisons of dropsonde and lidar data proved that the lidar is capable of measuring the wind direction and wind speed of this weak flow toward the alps 1 4 ms 1 the flow was up to 1500 m deep and it extended 80 km into the alpine foreland lidar data are volume measurements horizontal resolution 5 km vertical resolution 100 m therefore they are ideal for the investigation of the flow structure and the comparison to numerical models even the vertical velocities measured by the lidar agreed with the mass budget calculations in terms of both sign and magnitude the numerical simulations with the fifth generation pennsylvania state university ncar mesoscale model mm5 mesh size 2 and 6 km and the local model lm of the german weather service mesh size 2 8 and 7 km reproduced the general flow structure and the mass fluxes toward the alps within 86 144 of the observations

supra glacial deposition and flux of catastrophic rock slope failure debris south central alaska the ongoing debate over the effects of global environmental change on earth s cryosphere calls for detailed knowledge about process rates and their variability in cold environments in this context appraisals of the coupling between glacier dynamics and para glacial erosion rates in tectonically active mountains remain rare we contribute to filling this knowledge gap and present an unprecedented regional scale inventory of supra glacial sediment flux and hillslope erosion rates inferred from an analysis of 123 large 0 center dot 1km2 catastrophic bedrock landslides that fell onto glaciers in the chugach mountains alaska as documented by satellite images obtained between 1972 to 2008 assuming these supra glacial landslide deposits to be passive strain markers we infer minimum decadal scale sediment yields of 190 to 7400tkm 2yr 1 for a given glacier surface cross section impacted by episodic rock slope failure these rates compare to reported fluvial sediment yields in many mountain rivers but are an order of magnitude below the extreme sediment yields measured at the snouts of alaskan glaciers indicating that the bulk of debris discharged derives from en glacial sub glacial or ice proximal sources we estimate an average minimum para glacial erosion rate by large episodic rock slope failures at 0 center dot 5 0 center dot 7mmyr 1 in the chugach mountains over a 50 yr period with earthquakes likely being responsible for up to 73 of this rate though ranking amongst the highest decadal landslide erosion rates for this size of study area worldwide our inferred rates of hillslope erosion in the chugach mountains remain an order of magnitude below the pace of extremely rapid glacial sediment export and glacio isostatic surface uplift previously reported from the region

characteristics and transport mechanism of the nyixoi chongco rock avalanche on the tibetan plateau china abstract for studying rock avalanches complex surficial and internal characteristics have been regarded as important indicators for understanding avalanche transport mechanism in the present study deposits of a massive holocene rock avalanche termed the nyixoi chongco rock avalanche located on the lhasa terrane of tibetan plateau in china are investigated based on a combination of remote sensing data and in situ observations it is revealed that abundant surface landforms including toreva blocks longitudinal and transverse ridges en echelon ridges and hummocks are commonly developed corresponding to these surface morphologies a series of internal sedimentary structures including jigsaw structures inner shear zones aligned clasts diapiric structures convoluted laminations and basal decollements are also well developed through an analysis of these surficial and internal characteristics we propose that a rapid motion similar to a laminar flow most likely occurred after the avalanche mass detaching from the source area in this process the detached avalanche mass was mainly emplaced by a frictional simple shear process characterized by a bulldozing effect that occurred between the sliding mass and the substrate from the proximal to the distal sections of the avalanche the transport of the rock mass can be classified into four major processes an extension dominated sliding process in the transition zone a compression dominated sliding process in subzones iii 1 and iii 2 of the accumulation zone iii a sliding process co dominated by compression and lateral spreading in subzone iii 3 and a rapid radial spreading process in subzone iii 4 the results of our study provided an improved understanding of the transport mechanisms of this rock avalanche

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

did rock avalanche deposits modulate the late holocene advance of tiedemann glacier southern coast mountains british columbia canada abstract most glaciers in western north america with reliable age control achieved their maximum holocene extents during final advances of the little ice age tiedemann glacier a large alpine glacier in western canada is an enigma because the glacier constructed lateral moraines that are up to 90 m higher and extend 1 8 km farther downvalley than those constructed during the little ice age our data show that the activity of the glacier is more complex than originally documented and that the glacier advanced many times during the past six thousand years surface exposure dating and radiocarbon ages of stumps beneath till demonstrate that the glacier achieved its maximum holocene extent at about 2 7 ka we hypothesize that one or more rock avalanches delivered surface debris to the glacier and caused the 2 7 ka glacier advance to be much larger than can be explained by climate forcing to test our hypothesis we developed and used a surface debris advection routine coupled to an ice dynamics model our results show that even a moderately sized rock avalanche 10 10 6 m 3 delivered to the top of the ablation zone could cause the glacier to thicken and advance far beyond its little ice age limit

diurnal circulation of the bolivian altiplano part i observations in july and august 2003 a field campaign was conducted to explore the diurnal circulation of the bolivian altiplano vertical soundings by remote controlled aircraft yielded profiles of temperature pressure and humidity at six passes and in a valley pilot balloon observations provided wind profiles two permanent stations collected additional data typically inflow toward the altiplano commences a few hours after sunrise at about the time when the stable nocturnal layer near the ground is transformed by the solar heating into an almost neutrally stratified convective boundary layer the depth of the inflow layer is comparable to but normally less than that of this boundary layer there are indications of return flow aloft the inflow continues at least until sunset moisture is imported at the passes leading to the yungas in the east strong upvalley flows were found in the valley of the rio de la paz which connects the wide canyon of la paz with the tropical lowlands to the east inflow was absent at one of the passes despite favorable synoptic conditions cases of synoptically forced flows are presented as well where the diurnal signal is difficult to separate a simple flow scheme is presented that fits the observations reasonably well

dynamic modelling of entrainment in rapid landslides entrainment of path material is an important feature of many rapid landslides the associated increases in volume and changes in flow character can significantly influence mobility a simple material entrainment algorithm based on the assumption of natural exponential growth with displacement has been incorporated into a new computer model designed to simulate rapid landslide motion across 3d terrain the user controls the growth rate and can also implement a change in rheology at the onset of entrainment a hypothetical example is used to demonstrate the influence of the mass and momentum transfer assumptions a back analysis of the 1999 nomash river landslide is included to show that the simple model is capable of simulating the bulk characteristics of a complex event involving substantial entrainment key words landslides debris flows rock avalanches entrainment erosion dynamic modelling

rock avalanches that travel onto glaciers and related developments karakoram himalaya inner asia abstract catastrophic rock slope failures in rugged terrain commonly generate rock avalanches when these occur in glacier basins the extent of landslide run out and its emplacement geometry are affected by movement over ice substantial modifications of glacier activity and sedimentation can follow ice activity leads to rapid modification transport and dispersal of landslide debris the nature of these interactions is described from observations over 20 years at bualtar glacier in the karakoram in august 1986 rock avalanches descended onto the ablation zone of the glacier their moisture content and patterns of deposition were affected by travel over ice glacier movement increased sharply at and below the rock avalanche deposits and within a few months the glacier surged a second surge occurred 2 years later major slope failures and debris flows were triggered beyond the ice margins and ponded melt water led to small outburst floods by 2005 the landslide material had been transported some 9 km about one third of this distance in the surges eventually it was fully reworked to become less readily distinguishable from other heavy supraglacial debris a large area of thickened ice persisted where the debris reduced ablation a positive impact on mass balance equivalent to a 20 increase in annual accumulation however it occurred as a moving segment of the ablation zone in 10 years it had in effect replaced the mass transferred in the surges data for the mid 1980s indicate the rock avalanches exceeded pre existing supraglacial debris by roughly five times and over a 30 year period will equal almost 500 years of normal supraglacial transport to the glacier margins other impacts of the episode suggest a doubling of this contribution to denudation similar developments were observed at three other glaciers where recent rock avalanches occurred and at twenty one prehistoric rock avalanches newly identified as having spread over glaciers it seems inadequate to treat such events only as singular extremes or the landslide and glacial processes separately here they are interpreted as contributing to disturbance regime landscapes whose history reflects episodic and regionally specific responses to strong interference among different earth surface processes they generate polygenetic deposits and landforms that are morphologically complex individual episodes involve decades to millennia their numbers and repetition can over ride or redirect geotectonic and climatic conditions it is suggested they are major but hitherto misread or neglected elements of landform evolution in the karakoram and perhaps in other high mountains

using stereo satellite imagery to account for ablation entrainment and compaction in volume calculations for rock avalanches on glaciers application to the 2016 lamplugh rock avalanche in glacier bay national park alaska

glaciation of alpine valleys the glacier debris covered glacier rock glacier continuum abstract alpine ice varies from pure ice glaciers to partially debris covered glaciers to rock glaciers as defined by the degree of debris cover in many low to mid latitude mountain ranges the few bare ice glaciers that do exist in the present climate are small and are found where snow is focused by avalanches and where direct exposure to radiation is minimized instead valley heads are more likely to be populated by rock glaciers which can number in the hundreds these rock cloaked glaciers represent some of the most identifiable components of the cryosphere today in low to mid latitude settings and the over steepened snouts pose an often overlooked hazard to travel in alpine terrain geomorphically rock glaciers serve as conveyor belts atop which rock is pulled away from the base of cliffs in this work we show how rock glaciers can be treated as an end member case that is captured in numerical models of glaciers that include ice dynamics debris dynamics and the feedbacks between them specifically we focus on the transition from debris covered glaciers where the modern equilibrium line altitude ela intersects the topography to rock glaciers where the modern ela lies above the topography on debris covered glaciers i e glaciers with a partial rock mantle rock delivered to the glacier from its headwall or from sidewall debris swept into the glacier at tributary junctions travels englacially to emerge below the ela there it accumulates on the surface and damps the rate of melt of underlying ice this allows the termini of debris covered glaciers to extend beyond debris free counterparts thereby decreasing the ratio of accumulation area to total area of the glacier aar in contrast rock glaciers i e glaciers with a full rock mantle occur where and when the environmental ela rises above the topography they require avalanches and rockfall from steep headwalls the occurrence of rock glaciers reflects this dependence on avalanche sources because they are most common on lee sides of ridges and peaks where wind blown snow enhances the strength of the avalanche source to maintain positive mass balance the avalanche cone developed in the winter must be sufficiently thick not to melt entirely in the summer thus providing an ice accumulation area for the rock glacier in the absence of rockfall this would support a short cirque glacier the presence of debris however facilitates the development of rock glaciers with lengths of hundreds of meters thicknesses of tens of meters and speeds of meters per year that are well described by numerical models numerical models are used to explore the alpine glacier response to its climate history in warming climates a debris covered glacier can transform into a much shorter rock glacier leaving in its wake a thinning ice cored moraine rock glaciers will persist in landscapes well beyond debris free counterparts because they have much longer response times to climate change the headwaters of alpine basins with steep headwalls will therefore oscillate between glacier and rock glacier occupation over glacial interglacial cycles maintaining a means by which rock from the headwall can be conveyed away this enhances the asymmetry of alpine ridgelines with downwind valleys biting deeply into the range crests as originally noted by g k gilbert

sedimentological characterization of antarctic moraines using uavs and structure from motion photogrammetry in glacial environments particle size analysis of moraines provides insights into clast origin transport history depositional mechanism and processes of reworking traditional methods for grain size classification are labour intensive physically intrusive and are limited to patch scale 1m2 observation we develop emerging high resolution ground and unmanned aerial vehicle based structure from motion uav sfm photogrammetry to recover grain size information across an moraine surface in the heritage range antarctica sfm data products were benchmarked against equivalent datasets acquired using terrestrial laser scanning and were found to be accurate to within 1 7 and 50mm for patch and site scale modelling respectively grain size distributions were obtained through digital grain classification or photo sieving of patch scale sfm orthoimagery photo sieved distributions were accurate to 2mm compared to control distributions derived from dry sieving a relationship between patch scale median grain size and the standard deviation of local surface elevations was applied to a site scale uav sfm model to facilitate upscaling and the production of a spatially continuous map of the median grain size across a 0 3 km2 area of moraine this highly automated workflow for site scale sedimentological characterization eliminates much of the subjectivity associated with traditional methods and forms a sound basis for subsequent glaciological process interpretation and analysis

freshwater megaflood sedimentation what can we learn about generic processes abstract there is growing recognition that sedimentary deposits related to high energy large scale freshwater floods are widespread across the continents and in the main can be related to quaternary outbreak flows from ice dammed lakes such deposits may also occur in the neogene and earlier recognition of these megaflood deposits is hindered by the lack of well conditioned stratigraphic models of depositional successions however descriptions of successions from many locations often exhibit commonalities when compared carefully thus the primary purpose of this paper is to examine and condense the published stratigraphic and sedimentological evidence so as to identify the key signatures of megaflood successions the deposits often are the only record of a flood and so the secondary purpose is to interpret the sedimentary sequences in order to recreate the behaviour of floods through single and multiple events finally some pointers are provided as to those areas of sedimentological research that might be profitably explored in more depth to improve understanding of megaflood dynamics a key characteristic of megaflood deposits is the apparent massive appearance of single units which on closer inspection usually are amalgamated layers of similar grain size distribution individual beds and sets of beds are commonly near horizontal planar and laterally extensive successions evidently are not channelized and extensivity is indicative of simultaneous and coherent deposition over large areas localised large scale clinoforms or smaller scale cross beds are common associated with bar front or dune progradation respectively but otherwise extensivity implies that cross cutting erosional contacts notably steeply inclined examples and small scale scours are not common except immediately around large isolated clasts such as dropstones and ice blocks a common vertical stack of sequences in any one succession consists of 1 basal thick coarse parallel bedded units 2 large scale clinoforms 3 horizontally bedded thin laminated units 4 ripple and dune cross beds 5 silt beds and 6 succession capping debris flow deposits in some cases such a succession usually is indicative of a single cycle of waxing and waning flood flow generally dominated by high concentration suspension deposition onto plane beds the high power allows the transport of fine gravel and coarse sand in suspension leading upon deposition to relatively coarse beds from suspension fall out clay and silt is generally sparse or absent being transported further down the system at the scale of the hydrograph the successions indicate that flows initially accelerate and then decelerate with significant shorter period flow pulses also evident in the sedimentary signatures in parallel bedded sequences primarily during waxing flows bedload transport often was ineffective in sorting sediment due to the high rates of deposition from the highly sediment charged waters resulting in diffuse accretion surfaces at each location similar sequence stacks are common leading to the impression of rhythmic deposition from pulsing flow including from repetitive series of floods although often composed of coarse grains many sequence stacks excluding any debris flows are not dissimilar to turbidity flow sequences the bouma sequence in particular although there is limited experimental evidence for turbidity currents associated with high energy freshwater flows theory does not preclude the deposition of similar sedimentary motifs from high concentration flows such that an analogy between some megaflood sedimentary beds and turbidites is not unreasonable despite considerable variation in megaflood sedimentary successions commonalities occur which are indicative of similar processes of deposition from high energy floods at geographically different locations the changes in style of deposition throughout a succession provide clues as to the nature of the flood flows and this information could be used to improve estimates of flood hydrograph behaviour however hypotheses linking deposit characteristics to flow dynamics are currently ill conditioned and often poorly tested the majority of published studies describe the coarser scale stratigraphy with only passing reference to the fine scale structure of individual beds closer attention to lamination styles particle orientation and syn depositional deformation structures for example should provide information on the flow mechanics at the time of bed deposition thus better consideration of the sedimentology of megaflood deposit beds will lead to better understanding of the controlling hydraulics and should result in better models of flood deposition

dynamic simulation of the motion of fragmenting rock avalanches a mass referenced continuum model for dynamic analysis of rapid mass movement dan is verified by laboratory and field data increased earth pressure coefficients are used in this model to represent the dispersive pressures caused by fragmentation within a translating rock avalanche the numerical model demonstrates that increased runout in large rock avalanches can occur with normal friction coefficients if higher than normal internal pressures such as those believed to be generated by fragmentation are present the extent of the falling mountain rock avalanche deposit in new zealand is reproduced in the model with normal friction and high earth pressure coefficients to represent by analogy the additional internal pressures due to fragmentation it appears that if internal friction is changed by fragmentation it is only by a small amount and may increase rather than decrease to test this and to move beyond the present analogue model requires a better understanding of the rheology of fragmenting ro

stratified flow over a mountain with a gap linear theory and numerical simulations linear theory and numerical simulations are used to investigate gap flows both gaps embedded in a long mountain ridge and gaps located between two isolated mountain peaks are considered the study mainly focuses on level gaps so as to isolate three dimensional effects from two dimensional gravity wave propagation special attention is given to qualitative differences between the linear and the nonlinear flow regimes the linear regime being defined by the absence of gravity wave breaking in the linear regime wind and pressure perturbations along a level gap axis are found to be qualitatively similar to those over a mountain ridge or peak but of lower amplitude and longer horizontal wavelength they are caused by vertically propagating gravity waves radiating from the mountain ridges peaks towards the gap axis and by low level confluence within the gap in the nonlinear regime however these two processes are of minor importance due to upstream blocking and low level wave breaking instead the pressure difference across the mountain ridge primarily drives the gap flow which tends to be decoupled from the flow over the adjacent ridge in contrast to the linear regime gap winds are as strong as or even stronger than the winds over the mountain ridge surface friction is found to reduce the near surface wind speed more strongly for mountain ridges than for gaps copyright 2002 royal meteorological society

reconstructing morphometric change in a proglacial landscape using historical aerial photography and automated dem generation this paper explores the feasibility of using historical aerial photographs and digital photogrammetric procedures to reconstruct morphometric landscape changes in a proglacial setting of the southern coast mountains british columbia canada the photographic record includes 12 sets of vertical photography obtained at a range of large to medium nominal scales for the period 1947 to 1997 an automated procedure of digital elevation model dem extraction was employed and details of morphometric change were assessed by differencing the dem surfaces obtained for different dates of photography results are used to describe terrain surface changes associated with glacier recession moraine gully erosion and forest growth in the glacial forefield methods are reviewed for the estimation and handling of systematic and random vertical errors in the dems that are suitable for this type of environment where there are no historical surveys or monuments to use as a common benchmark and only natural features are available for establishing ground control digital photogrammetry applied to scanned archived photography can be used to generate high resolution sub meter dem surfaces of proglacial terrain suitable for quantifying decadal scale morphometric changes that have occurred since the mid 20th century to recent times potential applications of these techniques and the associated historical data are discussed

stability of supraglacial debris rock debris on the surface of ablating glaciers is not static and is often transported across the ice surface as relief evolves during melt this supraglacial debris transport has a strong influence on the spatial distribution of melt and is implicated in the formation of hummocky glacial topography in deglaciated terrain furthermore as ice dammed lakes and ice cored slopes become increasingly common in deglaciating watersheds there is rising concern about hazards to humans and infrastructure posed by mass wasting of ice cored debris the existing quantitative framework for describing these debris transport processes is limited making it difficult to account for transport in mass balance hazard assessment and landscape development models this paper develops a theoretical framework for assessing slope stability and gravitational mass transport in a debris covered ice setting excess water pressure at the interface between ablating ice and lowering debris is computed by combining darcy s law with a meltwater balance a limit equilibrium slope stability analysis is then applied to hypothetical debris layers with end member moisture conditions derived from a downslope meltwater balance that includes production and seepage the resulting model system constrains maximum stable slope angles and lengths that vary with debris texture thickness and the rate of meltwater production model predictions are compared with field observations and with digital elevation model dem derived terrain metrics from two modern debris covered glaciers on mount rainier usa copyright 2017 john wiley sons ltd

debris thickness patterns on debris covered glaciers abstract many debris covered glaciers have broadly similar debris thickness patterns surface debris thickens and tends to transition from convex to concave up down glacier we explain this pattern using theory analytical and numerical models paired with empirical observations down glacier debris thickening results from the conveyor belt like nature of the glacier surface in the ablation zone debris can typically only be added but not removed and from the inevitable decline in ice surface velocity toward the terminus down glacier thickening of debris leads to the reduction of sub debris melt and debris emergence toward the terminus convex up debris thickness patterns occur near the up glacier end of debris covers where debris emergence dominates ablation controlled concave up debris thickness patterns occur toward glacier termini where declining surface velocities dominate velocity controlled a convex concave debris thickness profile inevitably results from the transition between ablation control and velocity control down glacier debris thickness patterns deviating from this longitudinal shape are most likely caused by changes in hillslope debris supply through time by establishing this expected debris thickness pattern the effects of climate change on debris cover can be better identified

diurnal winds in the himalayan kali gandaki valley part i observations abstract the diurnal wind system of the kali gandaki valley in nepal was explored in september and october 1998 in a field campaign using pilot balloons as the main observational tool this valley connects the plateau of tibet with the indian plains the river crosses the himalayas forming the deepest valley on earth intense upvalley winds blow up this valley during the day observations were made along the river at various spots selected between the exit point from the himalayas and the source close to the plateau of tibet the strongest upvalley winds were found between marpha and chuksang with typical speeds of 15 20 m s 1 the upvalley wind sets in first at the ground but an upvalley wind layer of 1000 2000 m depth forms quickly after the onset this deep inflow layer persists up to lo manthang a town located a few kilometers south of the plateau of tibet deceleration in the late afternoon and evening also appears to commence near the ground weak drainage flow forms late in the night the causes o

distinguishing depositional setting for sandy deposits in coastal landscapes using grain shape abstract several methods exist that use sediment properties to characterize depositional setting and related mechanisms of transport including analysis of grain size distributions sediment petrology micromorphology and grain structure techniques that rely on electron or optical microscopy produce results with varying degrees of success and applicability here a new method is presented and used to differentiate between littoral and eolian sands that were extracted from recently formed landforms as well as landforms that are from mid to late holocene in age the method utilizes a standard optical microscope with a mounted digital camera paired with freely available software imagej to characterize grain shape parameters the method was tested on nearly 6000 sand grains from samples with varied transport histories and it was found that grain solidity was the most distinguishable characteristic between eolian and littoral samples differentiating them 86 of the time for calibration samples the method was used to correctly identify the mechanism of transport for 76 of the samples patterns in the results indicated that this method could be extended to link potential sediment sources to various depositional basins and future work includes testing the method in areas with a different mineralogy and or landscape history

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

evidence for a landslide origin of new zealand s waiho loop moraine the waiho loop moraine has been interpreted as evidence for younger dryas cooling in southern new zealand but recent dating and climatological studies have questioned this idea a detailed analysis of the sedimentology of the moraine suggests it was formed after a large landslide onto the franz josef glacier triggered a glacial surge independent of climate forcing

sedimentology of rock avalanche deposits case study and review abstract detailed sedimentological studies concerning different facies types and the factors influencing their development such as lithology topography substrates etc were carried out at the carbonate tschirgant rockslide rock avalanche deposit in the eastern alps of austria several depositional facies and sub facies have been identified at this and other sites by many researchers these facies are found throughout the debris regardless of depth or travel distance and result from highly heterogeneous stress distributions in time and space during emplacement one of the most important recent observations in terms of emplacement dynamics is that shear is not confined to the base but is distributed throughout the debris except the coarse carapace due to the preservation of source stratigraphy in these non turbulent mass movements any horizontal facies or grain size variations need to be regarded in context since they strongly depend on source stratigraphy and hence the spatial distribution of lithologies i e geological units of different mechanical properties for example some lithologies do not form a boulder carapace due to absence of large in situ blocks in the source rock mass however at tschirgant slight facies maturation with distance within the same lithology is observed i e clast fragmentation progresses to create the distinct facies characteristic grain size distribution only after some distance travelled these details are revealed through facies based sampling and analysis studies based on bulk sampling in some cases observed progressively reduced grain sizes with distance and depth which might be a function of added variations within different facies sampled together in this paper the wealth of observations on rockslide and rock avalanche sedimentology of the past decades is combined with a detailed case study of a lithologically relatively simple deposit to outline global and site specific depositional structures and facies with the aim to summarize review and refine the current state of knowledge on rock avalanche and rockslide emplacement processes

a model for the runout analysis of rapid flow slides debris flows and avalanches runout analyses are used for risk assessment and design of remedial measures against rapid landslides such as debris flows debris avalanches rockslide avalanches large scale liquefaction failure

a subsynoptic analysis of the denver tornadoes of 3 june 1981 abstract on the afternoon of 3 june 1981 a severe thunderstorm spawned two tornadoes which moved across a portion of metropolitan denver the tornadoes were classified as strong f2 intensity and caused damage totaling over 1 5 million the synoptic scale setting for this event was similar to that associated with many other occurrences of severe convection in eastern colorado with post frontal moist southeasterly upslope flow at low levels and southwesterly flow aloft in advance of an approaching trough we chose to study this event in part because of its occurrence within the profs program for regional observing and forecasting services surface mesonetwork emphasis is placed on mesoscale evolution culminating in the formation of the tornadic storm a zone of surface convergence and cyclonic vorticity developed during the early daylight hours over and north of denver between southeasterly flow over the plains and a region of lighter generally northerly flow just east of the foothills the tornadic s

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

geodetic mass balance of surge type black rapids glacier alaska 1980 2001 2010 including role of rockslide deposition and earthquake displacement we determine the geodetic mass balance of surge type black rapids glacier alaska for the time periods 1980 2001 and 2001 2010 by combining modern interferometric synthetic aperture radar insar derived digital elevation models dems dems derived from archival aerial imagery laser altimetry data and in situ surface elevation measurements our analysis accounts for both the large rockslides and terrain displacements caused by the 2002 m7 9 earthquake on the denali fault which runs through black rapids glacier to estimate uncertainties we apply monte carlo simulations for the earthquake triggered rockslides we find a volume of 56 62 2 86 106 m3 equivalent to an average debris thickness of 4 44 0 24 m across the 11 7 km2 deposit area on the glacier terrain displacement due to the earthquake corresponds to an apparent glacier volume change of 53 1 106 m3 which would cause an apparent specific mass balance of 0 19 meter water equivalent mwe if not taken into account the geodetic mass balance of black rapids glacier is 0 48 0 07 mwe a 1 for the entire 30 year period but more negative for the period 2001 2010 0 64 0 11 mwe a 1 than the period 1980 2001 0 42 0 11 mwe a 1 in agreement with trends indicated by in situ mass balance measurements elevation data indicate no net thickening of the surge reservoir between 1980 and 2010 in contrast to what is expected during the quiescent phase a surge of black rapids glacier in the near future is thus considered unlikely

early holocene 8 6 ka rock avalanche deposits obernberg valley eastern alps landform interpretation and kinematics of rapid mass movement in the obernberg valley the eastern alps landforms recently interpreted as moraines are re interpreted as rock avalanche deposits the catastrophic slope failure involved an initial rock volume of about 45 million m with a runout of 7 2 km over a total vertical distance of 1330 m fahrboschung 10 36cl surface exposure dating of boulders of the avalanche mass indicates an event age of 8 6 0 6 ka a 14c age of 7785 190 cal yr bp of a palaeosoil within an alluvial fan downlapping the rock avalanche is consistent with the event age the distal 2 km of the rock avalanche deposit is characterized by a highly regular array of transverse ridges that were previously interpreted as terminal moraines of late glacial jigsaw puzzle structure of gravel to boulder size clasts in the ridges and a matrix of cataclastic gouge indicate a rock avalanche origin for a wide altitude range the avalanche deposit is preserved and the event age of mass wasting precludes both runout over glacial ice and subsequent glacial overprint the regularly arrayed transverse ridges thus were formed during freezing of the rock avalanche deposits

geomorphological consequences of a glacier advance across a paraglacial rock avalanche deposit abstract glacial reworking of paraglacial rock slope sediment has been inferred from long deglaciated terrains to contribute significantly to glacial sediment transfer at feegletscher switzerland we provide the first description of the geomorphological consequences of glacier advance across paraglacial rock avalanche sediment this produced a small arcuate end moraine that encloses a zone of hummocky debris the sedimentology of these landforms is conditioned by rock avalanche sediment and can be differentiated from purely glacial sediments indicating that the contribution of glacially reworked rock avalanche debris may be recognisable in deglaciated terrain remarkably much of the overridden rock avalanche debris has maintained its angularity and delicate brecciation features despite up to 40 years of glacial action we suggest that the surface carapace facies of the rock avalanche deposit comprising large openwork blocks limited the effectiveness of glacial erosion processes the carapace facies will have resisted significant erosion by the relatively thin glacier because of its high shear strength and because it was able to transmit subglacial meltwater efficiently thus enhanced debris transfer associated with reworking of paraglacial rock avalanche sediment should not necessarily be expected during the initial stages of glacier advance

an improved method for computing horizontal diffusion in a sigma coordinate model and its application to simulations over mountainous topography abstract a set of modifications is presented to reduce the unphysical impact of horizontal diffusion in numerical models with a terrain following sigma coordinate system at model levels sufficiently far away from the ground vertical interpolation is used to compute diffusion truly horizontally when the coordinate surfaces are sloping close to the ground where truly horizontal computation of diffusion is not everywhere possible without intersecting the topography a combination of one sided truly horizontal diffusion and orography adjusted diffusion along the sigma surfaces is used for most of the variables the latter means that the diffusion coefficient is reduced strongly when the grid points involved in the computation of horizontal diffusion are located at greatly different heights for temperature one sided horizontal diffusion is not used because it damps the slope wind circulation in an unphysical way however a temperature gradient correction is applied to the terrain following part of the t

the sedimentology and geomorphology of rock avalanche deposits on glaciers this article describes and compares the deposits of four large landslides on two glaciers in alaska using field mapping and remote sensing digital image analysis is used to compare the sedimentological characteristics of nearly 200 000 individual surface blocks deposited by three landslides at black rapids glacier in 2002 the debris sheets of one of the three landslides on black rapids glacier and a landslide emplaced on sherman glacier in 1964 are also investigated the three landslides on black rapids glacier have undergone little post depositional modification by glacier flow whereas the sherman glacier landslide has been transported supraglacially up to ca 1k m over the past 46 years the three debris sheets on black rapids glacier have coarse blocky rims at their distal edges and all four debris sheets have longitudinal flowbands characterized by differences in texture and produced by shearing within the moving debris elongated blocks are parallel to flow except at the perimeter of the debris sheets where they are aligned more perpendicular to flow blocks on the sherman glacier debris sheet have been reoriented by glacier flow the matrix shows no systematic differences with depth or distance from the source however it appears to become coarser over a time scale of decades due to weathering

geomorphic and geologic controls of geohazards induced by nepal s 2015 gorkha earthquake the gorkha earthquake m 7 8 on 25 april 2015 and later aftershocks struck south asia killing 9 000 and damaging a large region supported by a large campaign of responsive satellite data acquisitions over the earthquake disaster zone our team undertook a satellite image survey of the earthquakes induced geohazards in nepal and china and an assessment of the geomorphic tectonic and lithologic controls on quake induced landslides timely analysis and communication aided response and recovery and informed decision makers we mapped 4 312 co seismic and post seismic landslides we also surveyed 491 glacier lakes for earthquake damage but found only 9 landslide impacted lakes and no visible satellite evidence of outbursts landslide densities correlate with slope peak ground acceleration surface downdrop and specific metamorphic lithologies and large plutonic intrusions

fragmentation energy in rock avalanches fragmentation is one of the mechanisms involved in rock avalanches quantifying the associated energy dur ing a rock avalanche can help to assess the influence of fragmentation on post failure mass movements in this paper in situ block size distributions of the intact rock mass and the debris deposits are presented and analyzed for nine rock avalanches five in the canadian rocky mountains and four in the european alps degrees of fragmentation are esti mated from these data two methods are examined to assess fragmentation energy one based on the comminution the ory and one on the blasting energy used in the mining industry the results show that for the studied rock avalanches there is a relationship between the reduction in diameter ratio rr d50 d50 where d50 and d50 are the mean diameter of the intact rock mass and the mean diameter of the debris respectively and the potential energy per unit volume normalized with respect to the point load strength of rock hg c where is the unit weight of the material hg is the vertical distance between the centres of gravity of the mass at the start and end positions and c is the point load strength for the cases studied fragmentation energy calculations average 20 of the potential energy an empirical relationship between rr and hg c has been established and is used in the definition of a disintegration index id this index seems to reflect the physics of the disintegration process since it accounts for the fact that the reduction in diameter ratio is a function of the dissipated energy and the strength of the rock these factors have long been known to affect fragmentation but have never been presented in a coherent manner for rock avalanches

an overview of recent large catastrophic landslides in northern british columbia canada at least thirty eight large catastrophic landslides each either larger than 0 5 m m 3 or longer than 1 km have occurred in northern british columbia in the last three decades the landslides include low gradient flowslides in cohesive sediments long runout rock slides rock avalanches and complex rock slide flows the flowslides have occurred in a variety of sediments including glaciolacustrine silt clay rich till and clay rich colluvium the rock failures have happened in weak shale overlain by sandstone and volcanic rocks the frequency of large landslides in northern british columbia appears to be increasing suggesting a link to climate change d 2005 elsevier b v all rights reserved

a glacial readvance during retreat of the cordilleran ice sheet british columbia central coast descriptions of the cordilleran ice sheet retreat after the last glacial maximum have included short lived readvances occurring during the older and younger dryas stadial periods and into the holocene but identification of these events has been largely limited to southwest and central british columbia and northwest washington state we present evidence of a late pleistocene readvance of cordilleran ice occurring on the central coast of british columbia on calvert island between northern vancouver island and haida gwaii evidence is provided by sedimentological and paleoecological information contained in a sedimentary sequence combined with geomorphic mapping of glacial features in the region results indicate that a cold climate existed between 15 1 and 14 3 cal ka bp and that ice advanced to and then retreated from the western edge of the island between 14 2 and 13 8 cal ka bp these data provide the first evidence of a major fluctuation in the retreating ice sheet margin in this region and suggest that a cold climate was a major factor in ice readvance these data contribute to the understanding of past temperature ice loading and crustal response the nature of ice margin retreat and the paleoenvironment of an understudied area of the pacific northwest

catastrophic landslides glacier behaviour and moraine formation a view from an active plate margin the influence of large bedrock landslides rock avalanches on the behaviour of glaciers is incompletely recognised here we present an example from an active tectonic margin in south island new zealand where large earthquakes leave a significant imprint on glacial records we demonstrate that terminal moraines on the western side of the southern alps record both ordinary i e climate driven and landslide initiated glacial advances following consideration of the processes involved in rock avalanche initiated moraine construction we suggest ways of determining the nature of the advance that built the terminal moraine the implications of these observations are important in breaking the conventional linkage of individual terminal moraines with climate forcing

large rock avalanches triggered by the m 7 9 denali fault alaska earthquake of 3 november 2002 the moment magnitude m 7 9 denali fault alaska earthquake of 3 november 2002 triggered thousands of landslides primarily rock falls and rock slides that ranged in volume from rock falls of a few cubic meters to rock avalanches having volumes as great as 20 10 6 m 3 the pattern of landsliding was unusual the number and concentration of triggered slides was much less than expected for an earthquake of this magnitude and the landslides were concentrated in a narrow zone about 30 km wide that straddled the fault rupture zone over its entire 300 km length despite the overall sparse landslide concentration the earthquake triggered several large rock avalanches that clustered along the western third of the rupture zone where acceleration levels and ground shaking frequencies are thought to have been the highest inferences about near field strong shaking characteristics drawn from interpretation of the landslide distribution are strikingly consistent with results of recent inversion modeling that indicate that high frequency energy generation was greatest in the western part of the fault rupture zone and decreased markedly to the east d 2005 elsevier b v all rights reserved

sedimentology and geomorphology of a large tsunamigenic landslide taan fiord alaska abstract on 17 october 2015 a landslide of roughly 60 106 m3 occurred at the terminus of tyndall glacier in taan fiord southeastern alaska it caused a tsunami that inundated an area over 20 km2 whereas the landslide debris itself deposited within a much smaller area of approximately 2 km2 it is a unique event in that the landslide debris was deposited into three very different environments on the glacier surface on land and in the marine waters of the fjord part of the debris traversed the width of the fjord and re emerged onto land depositing coherent hummocks with preserved source stratigraphy on an alluvial fan and adjacent moraines on the far side of the fjord imagery from before the landslide shows that the catastrophic slope failure was preceded by deformation and sliding for at least the two decades since the glacier retreated to its current terminus location exposing steep and extensively faulted slopes a small volume of the total slide mass remains within the source area and is topped by striated blocks 10 m across and standing trees that were transported down the slope in intact positions during the landslide field work was carried out in the summer of 2016 and by the time this paper was written almost all of the supraglacial debris was advected into the fjord and half the subaerial hummocks were buried by glacial advance this rapid change illustrates how highly active sedimentary processes in high altitude glacial settings can skew any landslide frequency analyses and emphasizes the need for timely field investigations of these natural hazards

thermally driven flows at an asymmetric valley exit observations and model studies at the lech valley exit the summertime thermal circulation in the region of an asymmetric valley exit is investigated by means of observations and high resolution model simulations the northeastward oriented alpine lech valley opening into the bavarian alpine foreland has an eastern slope exceeding the western slope by about 15 km northerly winds along the eastern slope are frequently observed reaching substantial strength during fair weather conditions a field experiment has been conducted to explore this phenomenon and to pinpoint the connection of the northeasterly flow to the lech valley wind circulation numerical simulations have also been carried out to support the interpretation of the observations it is found that the northerlies owe their existence to the dominantly easterly flow along the foothills of the alps which is partly induced by the alpine heat low but may be strengthened by favorable synoptic conditions examples for both situations will be discussed the diurnal flow in the lech valley has little obvious impact on these northeasterlies on days with moderate synoptic easterly flow a wake is present on the lee of the eastern slope of the exit region accompanied by a shear zone along the edge of the wake this shear zone is forced southward during the daytime because of thermally initiated pressure gradients between the alpine foreland and the alps leading to sudden wind changes in the exit area at the time of its passage

fragmentation in the val pola rock avalanche italian alps 1 grain size data from the deposit of the 1987 val pola rock avalanche central italian alps are compared with data concerning rock avalanching rock fragmentation and comminution the weibull distribution fits a small part of the entire particle size distribution of debris samples with a mean value of the curve shape factor of 0 54 0 28 this is typical of multiple comminution or fragmentation with much shearing a fractal distribution fits over a greater size range computed fractal dimensions range between 1 3 and 3 2 within the deposit with average values of about 2 6 2 7 these values cover the range between the theoretical values of the plane of weakness model 1 97 and the pillar of strength model 2 84 and are close to the theoretical value for the constrained comminution model 2 58 these suggest that both texturally mature and immature deposits are present and that more than a single comminution process acted during the rock avalanche motion variation of the grain size distribution within the deposit and grain size segregation show as trends in the fractal dimension and arise from variation in the fragmentation process a variety of different physical and empirical laws suggest that 1 30 of the energy expended in the rock avalanche was consumed in fragmentation

catastrophic detachment and high velocity long runout flow of kolka glacier caucasus mountains russia in 2002 abstract in september 2002 a catastrophic geomorphic event occurred in the caucasus mountains southern russia in which almost the entire mass of kolka glacier detached from its bed accelerated to a very high velocity max 65 80 m s and traveled a total distance of 19 km downstream as a glacier debris flow based on the interpretation of satellite imagery obtained only 8 5 h before the event occurred the analysis of seismograms from nearby seismic stations and subsequent detailed field observations and measurements we suggest that this remarkable event was not a response to impulse loading from a rock avalanche in the mountainside above the glacier or to glacier surging but due entirely to the static and delayed catastrophic response of the kolka glacier to ice and debris loading over a period of months prior to the september 20 detachment we reconstruct the glacier debris flow using field observations in conjunction with the interpretation of seismographs from nearby seismic stations and successfully simulate the behaviour runout velocity and deposition of the post detachment glacier debris flow using a three dimensional analytical model our demonstration of a standing start hypothesis in the 2002 kolka glacier detachment has substantial implications for glacier hazard assessment and risk management strategies in valleys downstream from unstable debris covered glaciers in the mountain regions of the world

random variation of fabric eigenvalues implications for the use of a axis fabric data to differentiate till facies fabric shape based on the relative values of three eigenvalues calculated from fabric data has been used to differentiate sediment facies and infer deformation histories the eigenvalues are based on samples drawn from parent populations and as such are subject to statistical variance due to sampling effects in this paper the degree of statistical variance in fabric data for two types of subglacial till from breidamerkurjokull iceland is investigated using bootstrapping techniques in which empirical confidence regions are built up by repeated resampling of the original data the experiments show that for each till type the observed between sample variability in the fabrics lies within the boundaries associated with random variations indicating that the observed range of fabric shapes within each till type is likely to be entirely the product of sampling effects differences in fabric shape between till types are generally greater than that associated with random variations indicating that their fabric shape characteristics as measured by eigenvalues are significantly different nevertheless the results suggest that great care should be exercised when using a axis fabric data to differentiate sedimentary facies or to infer subtle differences in physical processes or conditions copyright 2001 john wiley sons ltd

one million cubic kilometers of fossil ice in valles marineris relicts of a 3 5 gy old glacial landsystem along the martian equator abstract self consistent landform assemblages suggest that valles marineris the giant valley system that stretches along the martian equator was entirely glaciated during late noachian to early hesperian times and still contains huge volumes of fossil ice some of these glacial landform assemblages are illustrated here with representative examples selected in three regions ius chasma central candor chasma and the junction between coprates chasma and capri chasma a morphological boundary separating an upper spur and gully morphology from a smooth basal escarpment has been spectacularly preserved along valley walls throughout valles marineris the boundary winds around topographic obstacles and displays long wavelength variations in elevation it is associated with lateral benches hanging valleys and truncated spurs comparisons with terrestrial analogs indicate that it is most reasonably interpreted as a glacial trimline chasma floors are covered by various kinds of terrains including hummocky terrains platy terrains lateral banks layered benches and a draping mantle landforms in these terrains and their spatial relationship with the interpreted trimline suggest that they correspond to various disintegration stages of an ancient glacial fill currently protected by a superficial cover of ablation till altogether these landforms and terrains compose a full glacial landsystem with wet based glaciers that were able to flow and slide over their beds it was most probably fed by ice accumulating at low elevations directly from the atmosphere onto valley floors and walls with only minor contributions from tributary glaciers flowing down from higher elevations similar fossil glacial landsystems dating back from the early martian history are to be expected in many other low latitude troughs such as chasmata chaos valleys impact craters and other basins

the denver cyclone part i generation in low froude number flow abstract a numerical model is used to study the denver cyclone a mesoscale vortex that develops in eastern colorado under southerly to southeasterly flow diurnal effects e g surface heating cooling have been excluded from these simulations but are discussed in part ii of this study simulations are first performed with a southerly ambient wind i e parallel to the continental divide if the froude number of the flow based on the height of the palmer divide an east west ridge to the south of denver is small then a vortex forms over the denver region this circulation then propagates northward at just over half the upstream flow velocity leaving essentially stagnant air in the lee of the palmer divide it is shown that coriolis turning has a negligible effect on the flow when the ambient wind is from the south however when the ambient wind is at an angle to the continental divide northerly winds can develop along the foothills due to coriolis turning of the flow as it approaches the divid

glacigenic clast fabrics genetic fingerprint or wishful thinking the interpretation of glacigenic diamictons is a subjective process for which quantitative support is frequently sought from parameters such as clast shape and fabric it has been widely suggested that different glacigenic diamicton facies possess distinct clast fabric signatures this paper examines this concept using a data set of 111 clast fabrics and a synthesis of published results eigenvalues are calculated and compared for a variety sedimentary facies it is concluded that clast fabric alone is not able to discriminate between different glacigenic facies and it is argued that clast fabric offers little quantitative support in the interpretation of glacigenic sediments it is suggested therefore that although clast fabric may continue to have a role as an indicator of relative strain at specific sites its use in the discrimination of glacigenic facies is limited consequently we should be much more selective in undertaking such analyses in the future copyright 1999 john wiley sons ltd

diurnal winds in the himalayan kali gandaki valley part iii remotely piloted aircraft soundings abstract in 1998 a field campaign has been conducted in the north south oriented kali gandaki valley in nepal to explore the structure of its extreme valley wind system piloted ballon pibal observations were made to map the strong upvalley winds as well as the weak nocturnal flows part i the stratification of the valley atmosphere was not explored in part ii of this multipart paper numerical simulations are presented that successfully simulate most of the wind observations moreover the model results suggest that the vigorous upvalley winds can be seen as supercritical flow induced by contractions of the valley here the results of a further campaign are reported where remotely piloted airplanes were used to obtain vertical profiles of temperature and humidity up to heights of 2000 m above the ground such profiles are needed for an understanding of the flow dynamics in the valley and for a validation of the model results this technique is novel in some respects and turned out to be highly rel

catastrophic landslide deposits in the karakoram himalaya in july 1986 three catastrophic landslides deposited about 20 x 106 cubic meters of debris on bualtar glacier in the karakoram himalaya a sudden acceleration and superficial breakup of the glacier provided an opportunity to examine the fresh deposits in depth beneath a surface layer of large boulders finer materials mainly sand and silt made up half of the total volume the fine materials were formed during the rock avalanche from mostly intact massive rock of the source zone velocity estimates suggest that this disaggregation occurred in less than 2 minutes coarse materials remained in bands of uniform lithology but the fine materials had diffused throughout the landslides a small amount of carbonate appears to have been calcined by frictional heating presumably at the base of the initial sliding masses these observations are relevant to understanding the mechanisms of catastrophic landslides other nearby rock avalanche deposits indicate that landslides are an important geomorphic process in the area and that they pose a continuing risk to human activity

the upper pleistocene on the northern face of the guadarrama mountains central spain palaeoclimatic phases and glacial activity abstract the present paper provides new information on pleistocene glacial activity in a mountainous area of the iberian central system a sediment analysis associated with pleistocene modelling was carried out using 1 granulometric and morphometric procedures 2 quartz grain microtexture techniques sem to discriminate between glacial and no glacial origins of sediments 3 clay x ray diffraction study to determine intra pleistocene climate variability and 4 optically stimulated luminescence osl absolute dating the results show that the sediments were formed in two different phases associated with glacial dynamics one of them was 35 30 ky bp and another was 25 20 ky bp separated by a short intermediate warm wet period identification of glacial phenomena is new for the northern slopes of the guadarrama mountains facing the north meseta duero basin although they are not unusual within the general context of the iberian central system from the data provided we deduce that glaciation in these mountains was much more intense and widespread than had previously been thought because on the northern slopes glaciers occupied large areas reaching the base of the mountains the evidence favours new interpretations of pleistocene morphology in the centre of the iberian peninsula and by extension on the southwestern edge of europe it also highlights the sensitivity of mountainous areas with regard to quaternary climate changes

photo sieving a method for grain size analysis of coarse grained unconsolidated bedding surfaces the photo sieving method enables the grain size analysis of particles 10 mm from unconsolidated openwork bedding surfaces the accuracy is equal to the machine sieving method the sediment surface is photographed in the field using a camera stand the enlarged print is digitized for computer processing by tracing the outlines of the pebbles from the size and shape of the projection area of the individual pebble images the computer determines the ellipsoids of revolution classifies these ellipsoids and establishes their grain size distribution in percentage by weight thus photo sieving differs distinctly from point counting techniques with the aid of photo sieving the surface grain size distributions of larger sedimentary systems may be regularly mapped alluvial fans braided rivers both onshore and offshore coasts or areas of relict sediments and manganese nodules are suitable for this method

a fragmentation spreading model for long runout rock avalanches based on the observation that deposits of large rock avalanches consist predominantly of intensely fragmented rock debris it is proposed that the processes of rock fragmentation are significant ca