regionally differentiated contribution of mountain glaciers and ice caps to future sea level rise the contribution to sea level rise from mountain glaciers and ice caps has grown over the past decades a projection of their melting during the twenty first century based on temperature and precipitation projections from ten climate models suggests that by 2100 these glaciers will lose about 21 of their total global volume

ice moraine and landslide dams in mountainous terrain we review recent work on ice moraine and landslide dams in mountainous terrain thus complementing several comprehensive summaries on glacier dams in intracontinental and arctic areas of low relief we discuss the roles of tectonic and climatic forcing on ice moraine and landslide dam formation and sudden drainage and focus on similarities and differences between their geomorphic impacts on confined valleys drained by steep bedrock and gravel bed rivers despite numerous reported failures of natural dams in mountain belts throughout the world their relevance to long term dynamics of mountain rivers remains poorly quantified all types of dams exert local base level controls thus trapping incoming sediment and inhibiting fluvial bedrock incision pervasive geomorphic and sedimentary evidence of outburst events is preserved even in areas of high erosion rates suggesting that sudden dam failures are characterized by processes of catastrophic valley floor aggradation active channel widening and downstream dispersion of sediment during which little bedrock erosion seems to be achieved we find that in the absence of direct evidence of former dams a number of similarities among the geomorphic and sedimentologic characteristics of catastrophic outburst flows may give rise to ambiguous inferences on the dam forming process this is especially the case for tectonically active mountain belts where there is ample and comparable potential for the formation and failure of ice moraine landslide and polygenetic dams concomitant with climatic oscillations or earthquake disturbance hence the palaeoclimatic implications of erroneously inferring the cause of dam formation may be significant we recommend that future research on natural dams in mountainous terrain addresses a climate and earthquake controlled systematics in the pattern of formation and failure b quantification of response of mountain rivers to catastrophic outburst events and their concomitant process sequences c elaboration of a comprehensive classification of natural dams in mountainous terrain with special attention to polygenetic dams d physical based modelling of dam formation failure and routing of water and sediment outbursts and e quantitative controls on the contribution of natural dams to sediment budgets in mountainous terrain

debris bed friction of hard bedded glaciers 1 field measurements of debris bed friction on a smooth rock tablet at the bed of engabreen a hard bedded temperate glacier in northern norway indicated that basal ice containing 10 debris by volume exerted local shear traction of up to 500 kpa the corresponding bulk friction coefficient between the dirty basal ice and the tablet was between 0 05 and 0 08 a model of friction in which nonrotating spherical rock particles are held in frictional contact with the bed by bed normal ice flow can account for these measurements if the power law exponent for ice flowing past large clasts is 1 a small exponent n 2 is likely because stresses in ice are small and flow is transient numerical calculations of the bed normal drag force on a sphere in contact with a flat bed using n 1 show that this force can reach values several hundred times that on a sphere isolated from the bed thus drastically increasing frictional resistance various estimates of basal friction are obtained from this model for example the shear traction at the bed of a glacier sliding at 20 m a 1 with a geothermally induced melt rate of 0 006 m a 1 and an effective pressure of 300 kpa can exceed 100 kpa debris bed friction can therefore be a major component of sliding resistance contradicting the common assumption that debris bed friction is negligible

complete dynamic modeling calibration for the thurwieser rock avalanche italian central alps abstract few rock avalanches have been witnessed and no exact real time description is available the 2 5 m m 3 punta thurwieser rock avalanche september 2004 italian central alps is a unique event for which many quantitative observations have been gathered this is the first case ever of a natural rock avalanche being recorded on video and for which an almost exact value of the total time duration from initial detachment to final deposition is available the landslide travelled over 2 9 km from its source partially in a glacial environment the initial failure and the time for the complete evacuation of the source area were studied and assessed by a series of photos the mean front velocities along the path have been estimated from the video the final geometry and the characteristics of the deposit have been obtained by gps measurements aerial photos field surveys and laboratory tests a quasi 3d continuum dynamic analysis of the landslide motion has been performed assuming both a voellmy and a frictional rheology in the model dan 3d for the first time the landslide front velocities have been used for back analyses and calibration of the rheological parameters together with the final shape and thickness of the deposit and its developing extension the dynamic flow resistance parameters initially calibrated with dan were adopted and validated in dan 3d showing good consistency they are consistent with the existing database for calibrated landslides of similar type and scale flow velocities on the path segment underlain by glacial deposits up to 55 65 m s 1 are more accurately predicted by adopting a frictional rheology up to 50 55 m s 1 with zero pore pressure and a 26 friction angle than by a voellmy rheology up to 40 45 m s 1 both observations and modelling show that glacial ice plays a substantial role in increasing the rock avalanche mobility

the last 1 million years of the extinct genus discoaster plio pleistocene environment and productivity at site u1476 mozambique channel abstract a detailed paleoenvironment reconstruction from the mozambique channel western indian ocean based on the calcareous nannoplankton assemblages was conducted for the interval between 2 85 and 1 85 myr this study covers the period during which the successive extinction of the last five species of discoasters occurred new productivity data obtained from the abundances of the discoaster species discoaster brouweri d triradiatus d pentaradiatus d surculus and d tamalis and other indicative calcareous nannoplankton taxa showed abundance variations which were at paced with the 100 41 and 23 kyr astronomical periodicities a shift in the productivity and water column stratification proxies occurred at 2 4 ma after the onset of the northern hemisphere glaciation here we propose that the variability recorded at international ocean discovery program site u1476 reflects the interplay between forcing associated with warm tropical pacific and cold southern ocean influences the former is shown by consistent occurrence of warm water taxa calcidiscus leptoporus oolithotus spp rhabdosphaera clavigera syracosphaera spp umbellosphaera spp typical of indonesian throughflow surface waters on the other hand the occurrence of coccolithus pelagicus indicates the influence of cold nutrient rich sub antarctic surface waters a more mixed water column initiated at 2 4 ma and a consequent productivity increase led to the gradual reduction of the discoaster species until their extinction at 1 91 ma this period was characterized by the low values of the florisphaera profunda index and high abundances of upper photic zone flora indicative of nutrient rich surface water conditions high productivity at the location during this period could have also been amplified by localized upwelling events driven by the mozambique channel eddies

numerical modeling of the emplacement of socompa rock avalanche chile 1 the 7 5 ka socompa sector collapse emplaced 25 km3 of fragmented rock as a thin but widespread 500 km2 avalanche deposit followed by late stage sliding of 11 km3 as toreva blocks most of the avalanche mass was emplaced dry although saturation of a basal shear layer cannot be excluded modeling was carried out using the depth averaged granular flow equations in order to provide information on the flow behavior of this well preserved long run out avalanche results were constrained using structures preserved on the surface of the deposit as well as by deposit outline and run up a proxy for velocity models assuming constant dynamic friction fail to produce realistic results because the low basal friction angles 1 to 3 5 necessary to generate observed run out permit neither adequate deposition on slopes nor preservation of significant morphology on the deposit surface a reasonable fit is obtained however if the avalanche is assumed simply to experience a constant retarding stress of 50 100 kpa during flow this permits long run out as well as deposition on slopes and preservation of realistic depositional morphology in particular the model explains a prominent topographic escarpment on the deposit surface as the frozen front of a huge wave of debris reflected off surrounding hills the result that socompa avalanche experienced a small approximately constant retarding stress during emplacement is consistent with a previously published analysis of avalanche data

a review of catastrophic drainage of moraine dammed lakes in british columbia abstract moraine dammed lakes are common in the high mountains of british columbia most of these lakes formed when valley and cirque glaciers retreated from advanced positions achieved during the little ice age many moraine dams in british columbia are susceptible to failure because they are steep sided have relatively low width to height ratios comprise loose poorly sorted sediment and may contain ice cores or interstitial ice in addition the lakes commonly are bordered by steep slopes that are prone to snow and ice avalanches and rockfalls moraine dams generally fail by overtopping and incision the triggering event may be a heavy rainstorm or an avalanche or rockfall that generates waves that overtop the dam the dam can also be overtopped by an influx of water caused by sudden drainage of an upstream ice dammed lake jokulhlaup melting of moraine ice cores and piping are other possible failure mechanisms failures of moraine dams in british columbia produce destructive floods orders of magnitude larger than normal streamflows most outburst floods are characterized by an exponential increase in discharge followed by an abrupt drop to background levels when the water supply is exhausted peak discharges are controlled by dam characteristics the volume of water in the reservoir failure mechanisms and downstream topography and sediment availability for the same potential energy at the dam site floods from moraine dammed lakes have higher peak discharges than floods from glacier dammed lakes the floodwaters may mobilize large amounts of sediment as they travel down steep valleys producing highly mobile debris flows such flows have larger discharges and greater destructive impact than the floods from which they form moraine dam failures in british columbia and elsewhere are most frequent following extended periods of cool climate when large lateral and end moraines are built a period of protracted warming is required to trap lakes behind moraines and create conditions that lead to dam failure this sequence of events occurred only a few times during the holocene epoch most notably during the last several centuries glaciers built large moraines during the little ice age mainly during the 1700s and 1800s and lakes formed behind these moraines when climate warmed in the 1900s twentieth century climate warming is also responsible for recent moraine dam failures in mountains throughout the world warming from the late 1800s until about 1940 and again from 1965 to today destabilized moraine dams with interstitial or core ice the warming also forced glaciers to retreat prompting ice avalanches landslides and jokulhlaups that have destroyed some moraine dams

lessons from ontake san a comparative analysis of debris avalanche dynamics abstract dynamic aspects of the long runout ontake san debris avalanche are evaluated by a comparison of several models an unsteady numerical model assumes two dimensional flow of an incompressible biviscous or newtonian fluid represented as a continuum with a free surface internal deformation of the flowing mass is considered as well as boundary resistances thus flow thinning and deposit shape as well as flow kinematics may be modeled parameters are adjusted to match observed runout with additional constraints on velocity and emplacement time with abundant constraints for ontake san from careful field investigations by japanese research teams our analysis indicates that a substantial decrease in flow resistance occurred as a function of displacement constant property models that match runout tend to overestimate the peak velocities and to underestimate the emplacement times a staged increase in mobility in both constant volume and variable volume models leads to results consistent with field data runout in a channel overflow area was also modeled qualitatively similar results have been obtained by other researchers using simple sliding block models with empirical parameters a slide block model with rational parameter selection a modified flood simulation and a multi element frictional slide model the relative merits of these models are compared the field mechanisms associated with this mobility increase with displacement are poorly understood but the question is now identified as a target for future research at debris avalanche sites and some plausible mechanisms are considered the main reason probably involves the entrainment of river water and saturated sediment leading to enhanced efficiency of fluid pressure mechanisms with undrained shear in addition progressive shearing reduced the mean particle size and angularity and the cohesion and friction and apparent viscosity of avalanche debris near the wetted perimeter hydroplaning the shearing of water films and slurries may have occurred locally

frictionite as evidence for a large late quaternary rockslide near kanchenjunga sikkim himalayas india implications for extreme events in mountain relief destruction abstract we present sedimentologic and petrographic field evidence of an extremely large 2 5 109 m3 late quaternary rockslide around dzongri 24 km s of kanchenjunga 8585 m a s l widespread occurrence of shattered leucogranites and migmatites deposited discordantly on top of undisturbed augen gneisses and separated by micro brecciated sliding surfaces indicate rapid movement during a large rockslide event occurrence of frictionite hyalomylonite in mineral samples indicates short term temperatures of 600 c in the moving rockslide mass along a 12 sliding plane from a sw direction of movement we infer a source 8 km ne of the deposit 5 km s of pandim 6691 m a s l where today a thick leucogranite intrusion marks a zone of weakness and failure of a postulated former mountain crest the mechanism of movement the dip of the sliding surface and the deposit preservation along ridge tops require that the dzongri rockslide ran out over an ice filled prek chu valley hence we prefer earthquake shaking over undercutting and glacial debuttressing as a possible trigger mechanism a regional review of other similarly large and catastrophic himalayan rockslides indicates that leucogranite intrusions are highly conducive to large scale failure in the higher himalayan crystalline hhc importantly high erosion rates have rendered this large rockslide deposit undetectable by remote sensing or digital elevation data which are commonly used for identifying evidence of such extreme events quantifying the contribution of such giant landslides in destroying some of the highest relief on earth will thus need further research attention

acoustic fluidization and the extraordinary mobility of sturzstroms 1 sturzstroms are a rare category of rock avalanche that travel vast horizontal distances with only a comparatively small vertical drop in height their extraordinary mobility appears to be a consequence of sustained fluid like behavior during motion which persists even for driving stresses well below those normally associated with granular flows one mechanism that may explain this temporary increase in the mobility of rock debris is acoustic fluidization where transient high frequency pressure fluctuations generated during the initial collapse and subsequent flow of a mass of rock debris may locally relieve overburden stresses in the rock mass and thus reduce the frictional resistance to slip between fragments in this paper we develop the acoustic fluidization model for the mechanics of sturzstroms and discuss the conditions under which this process may sustain fluid like flow of large rock avalanches at low driving stresses

ice avalanches some empirical information about their formation and reach evaluation d apres l etude d environ 100 avalanches de glace des zones de rupture et des distances d arret

the role of rock fragmentation in the motion of large landslides abstract by considering the implications of the comminution generally associated with very large landslides we arrive at a simple explanation for the remarkably low frictional resistance to motion demonstrated by large intact blockslides e g waikaremoana new zealand volcanic debris avalanches e g socompa chile and large rock avalanches e g falling mountain n z which allows such mass movements to achieve unexpectedly high velocities and long runout distances during rapid grain flow under high direct stress the overall grain motion generates stresses in many force chains that strain individual grains to failure most of the elastic strain energy accumulated in these force chains before failure is returned at failure to the resulting grain fragments resulting in apparent instantaneous pressures of 3q on the surroundings where q is the ambient strength of the previously intact grains gpa these intense pressures support some of the direct force on the shear layer so that the effective intergranular stress in the shear layer is reduced because frictional resistance is proportional to effective stress this reduces the overall frictional resistance to shear the steady state effective stress is that which just allows fragmentation to continue the resistance to motion estimated from this relationship explains to much better than order of magnitude accuracy the reported motions of the large rapid mass movements we also deduce that grain fragmentation can be sustained for sufficiently long to explain the phenomena without reducing the mean grain size by volume in the granular layer to unrealistically small values the presence of pore fluid does not appear to influence the effect of fragmentation dynamics in a major way the proposed mechanism requires further laboratory and simulation studies to reduce its current dependence on limited field data but its success suggests that it is worthwhile investigating further as an explanation for large mass movements in the types of brittle rock in which fragmentation occurs

the effects of rockfall volume on runout distance the main goal of this paper is to clarify the effects of rockfall volume on its fluidization for this purpose outdoor rockfall experiments were carried out to analyze runout distances and individual movements of rockfall blocks and numerical simulations were conducted for these experiments to learn more about the mechanism of rockfall fluidization the rockfall experiments were conducted using an artificial slope on which granite slabs were surfaced and overlaid with cubiformed granite blocks the size and number of blocks were varied in this series of experiments further numerical simulations were carried out in which the coordinates of individual rockfall blocks were traced in three dimensional space from rockfall initiation to final deposition it became clear from the experiments and simulations that the runout distance had a positive correlation with the rockfall volume number of rockfall blocks and the runout distance of the gravity center of deposited rockfall mass had a negative correlation with the rockfall volume to clarify the mechanism of these two phenomena the positions of individual blocks from initial arrangements to final depositions were traced in the experimental and numerical simulations this revealed that the relative positions of each block along the slope direction were not changed during rockfall movement the reason for the block sequence preservation was that front facing blocks in the initial cube arrangement accelerated and rear facing blocks decelerated along the slope by internal collision between blocks further as the rockfall volume increased the opportunities for impact among the rockfall blocks increased with the front facing blocks pushed farther whereas the gravity center of the deposited rockfall mass had an inclination to travel shorter distances as rockfall blocks increased according to the increase of kinetic energy dispersed by the collision of blocks

comparison of new and existing global digital elevation models aster g dem and srtm 3 1 a new global elevation dataset known as g dem based on the aster satellite imagery will be released in late 2008 g dem will be the best freely available global digital elevation model dem at a horizontal resolution of 1 arc second we assess the quality of g dem in comparison with 3 arc second srtm dem the best current global elevation dataset basic geomorphometric parameters elevation slope and curvature were examined for a pre release version of g dem and srtm dem for western japan g dem has fewer missing cells than srtm dem particularly in steep terrain also g dem gives smoother and more realistic representations of lowlands valleys steep slopes and mountain ridges whereas srtm dem includes many local spikes and holes and tends to overestimate valley floor elevation and underestimate ridge elevation g dem will be commonly used in geoscientific studies because of its higher resolution fewer missing data and better topographic representation than srtm dem

a re examination of the mechanism and human impact of catastrophic mass flows originating on nevado huascaran cordillera blanca peru in 1962 and 1970 abstract the 1962 and 1970 huascaran mass movements originated as rock ice falls from the mountain s north peak transformed into higher volume high velocity mud rich debris flows by incorporation of snow from the surface of a glacier below huascaran and the substantial entrainment of morainic and colluvial material from slopes below the glacier terminus water for fluidization of the entrained material originated in the melting of incorporated snow and the liberation of soil moisture contained within the entrained materials eyewitness reports indicate very high mean velocities for the events 17 35 m s 1962 and 50 85 m s 1970 the runout distances and velocity profiles of both events were simulated using dan w both mass movements continued downstream in the rio santa as debris floods aluviones that in 1970 reached the pacific at a distance of 180 km in strong contrast to publications in the geosciences literature 1961 peru census data indicates that the death toll of the 1970 event is ca 6000 and that total life loss in the two events did not exceed 7000 people

back calculation of the in den arelen avalanche with ramms interpretation of model results two and three dimensional avalanche dynamics models are being increasingly used in hazard mitigation studies these models can provide improved and more accurate results for hazard mapping than the simple one dimensional models presently used in practice however two and three dimensional models generate an extensive amount of output data making the interpretation of simulation results more difficult to perform a simulation in three dimensional terrain numerical models require a digital elevation model specification of avalanche release areas spatial extent and volume selection of solution methods finding an adequate calculation resolution and finally the choice of friction parameters in this paper the importance and difficulty of correctly setting up and analysing the results of a numerical avalanche dynamics simulation is discussed we apply the two dimensional simulation program ramms to the 1968 extreme avalanche event in den arelen w e show the effect of model input variations on simulation results and the dangers and complexities in their interpretation

flow of variably fluidized granular masses across three dimensional terrain 1 coulomb mixture theory rock avalanches debris flows and related phenomena consist of grain fluid mixtures that move across three dimensional terrain in all these phenomena the same basic forces govern motion but differing mixture compositions initial conditions and boundary conditions yield varied dynamics and deposits to predict motion of diverse grain fluid masses from initiation to deposition we develop a depth averaged three dimensional mathematical model that accounts explicitly for solid and fluid phase forces and interactions model input consists of initial conditions path topography basal and internal friction angles of solid grains viscosity of pore fluid mixture density and a mixture diffusivity that controls pore pressure dissipation because these properties are constrained by independent measurements the model requires little or no calibration and yields readily testable predictions in the limit of vanishing coulomb friction due to persistent high fluid pressure the model equations describe motion of viscous floods and in the limit of vanishing fluid stress they describe one phase granular avalanches analysis of intermediate phenomena such as debris flows and pyroclastic flows requires use of the full mixture equations which can simulate interaction of high friction surge fronts with more fluid debris that follows special numerical methods described in the companion paper are necessary to solve the full equations but exact analytical solutions of simplified equations provide critical insight an analytical solution for translational motion of a coulomb mixture accelerating from rest and descending a uniform slope demonstrates that steady flow can occur only asymptotically a solution for the asymptotic limit of steady flow in a rectangular channel explains why shear may be concentrated in narrow marginal bands that border a plug of translating debris solutions for static equilibrium of source areas describe conditions of incipient slope instability and other static solutions show that nonuniform distributions of pore fluid pressure produce bluntly tapered vertical profiles at the margins of deposits simplified equations and solutions may apply in additional situations identified by a scaling analysis assessment of dimensionless scaling parameters also reveals that miniature laboratory experiments poorly simulate the dynamics of full scale flows in which fluid effects are significant therefore large geophysical flows can exhibit dynamics not evident at laboratory scales

recent and future warm extreme events and high mountain slope stability the number of large slope failures in some high mountain regions such as the european alps has increased during the past two to three decades there is concern that recent climate change is driving this increase in slope failures thus possibly further exacerbating the hazard in the future although the effects of a gradual temperature rise on glaciers and permafrost have been extensively studied the impacts of short term unusually warm temperature increases on slope stability in high mountains remain largely unexplored we describe several large slope failures in rock and ice in recent years in alaska new zealand and the european alps and analyse weather patterns in the days and weeks before the failures although we did not find one general temperature pattern all the failures were preceded by unusually warm periods some happened immediately after temperatures suddenly dropped to freezing we assessed the frequency of warm extremes in the future by analysing eight regional climate models from the recently completed european union programme ensembles for the central swiss alps the models show an increase in the higher frequency of high temperature events for the period 2001 2050 compared with a 1951 2000 reference period warm events lasting 5 10 and 30 days are projected to increase by about 1 5 4 times by 2050 and in some models by up to 10 times warm extremes can trigger large landslides in temperature sensitive high mountains by enhancing the production of water by melt of snow and ice and by rapid thaw although these processes reduce slope strength they must be considered within the local geological glaciological and topographic context of a slope

collapse at the eastern eiger flank in the swiss alps on 13 june 2006 parts of the eastern flank of the eiger peak in the swiss alps collapsed leading to a major rock fall the unstable spur on this flank is made up of several blocks that move relative to one another instability was initiated by a block at the rear that acted as a wedge and triggered motion of the other blocks landslides are a significant natural hazard in mountainous regions1 and are often triggered by external factors such as earthquakes rainfall permafrost melting or retreat of glaciers2 a large landslide occurred in the swiss alps on 13 july 2006 when portions of an immense rock spur on the eastern flank of the eiger peak3 collapsed here we use field observations and terrestrial laser scanning data to record and quantify the relative motion along the various blocks of rock that form this spur the data show that during the year of observation the blocks moved relative to one another by up to tens of metres along fractures that can be related to pre existing planes of weakness rates of motion and deformation were high throughout july 2006 particularly in the northern part of the spur that partially collapsed on 13 july the rates decreased considerably during the subsequent months although a slight increase was noted in june and july 2007 these observations are consistent with instability of the spur initiated by subsidence of a single block at the rear which acted as a wedge and disintegrated over time owing to loss of lateral confinement

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

self lubrication for long runout landslides examination by computer simulation this paper describes the use of a discrete particle computer simulation to test whether the apparent low friction exhibited by long runout landslides could be explained in terms of simple granular mechanics the flow structure consists of an active basal shear zone supporting the majority of the landslide which travels as a relatively solid plug the observed runout appears to depend on the total energy dissipation which is a trade off between 1 the inelasticity of the particles which governs the energy dissipated in each event and 2 the size of the dissipating shear zone which governs the number of particles that are actively dissipating energy very inelastic particles quickly dissipate the work performed at boundaries and result in thin dissipative zones as a result these two factors balance and the runout is nearly independent of particle inelasticity along the same lines increasing the boundary roughness was found to increase the size of the dissipative shear zone and markedly decrease the runout also a distribution of particle sizes destroyed ordered structures within the body which once again increases the dissipation and decreases the runout unfortunately the simulations also indicate that the runout should be independent of the depth of the flow and thus cannot account for the observed volumetric effect on runout

predictability of long runout landslide motion implications from granular flow mechanics quality of landslide motion prediction is directly linked to the understanding of the basic flow mechanisms although it is known that landslides are granular mass flows and granular flow mechanics is an established area of research hypotheses on landslide motion are still based on simple geometrical relations and heuristic assumptions new insights into the development of flow properties of high speed high concentration granular flows are given by results of discrete particle simulations rapid granular flows are self organizing dynamic systems that are forced to develop a plastic body rheology this behaviour must be described by a coefficient of internal friction cm that refers to the center of mass of a flow coefficients of rapid granular flows of inelastic and rough particles which are typical for common rock materials do not vary significantly around cm 0 45 that is definitively smaller than the friction coefficient of soil creep 0 6 the motion of the center of mass is superimposed by the spreading of the granular mass that is controlled by the same plastic body rheology this combined motion is a scale invariant self similar process that depends only on the drop height of a landslide and its volume this allows specification of implications that must be given special attention in the development of future models for landslide prediction

giant m8 earthquake triggered ice avalanches in the eastern kunlun shan northern tibet characteristics nature and dynamics several giant ice avalanches were initiated by slope failure from ice caps due to strong ground motion during the 14 november 2001 m w 7 9 kokoxili earthquake on the kunlun fault four ice avalanches were identified on the north slope of the burhan budai shan several kilometers east of the kunlun pass and two were identified on the south slope of the eastern yuxi feng which is 50 km west of the kunlun pass these ice avalanches originated from steep sided ice caps and progressed over and past the termini of outlet valley glaciers in the burhan budai shan the ice avalanches comprised ice and snow that reached 2 3 km down valley beyond the snouts of the contemporary glaciers detailed study of the largest ice avalanche b2 shows that the initial movement over the contemporary glacier was turbulent in nature having a velocity 35 ms 1 beyond the contemporary glacier the ice avalanche was confined within steep valley walls and entrenched paraglacial fans before coming to rest this ice avalanche moved as a bingham plastic flow at a velocity of 21 ms 1 these ice avalanches transported little rock debris and it is thus unlikely that they are important in contributing to the landscape evolution of this region yet given the appropriate geologic and climatic conditions ice avalanching may be an important process in the landscape evolution of high mountainous terrains the frequency of such events is unknown but such phenomena may become more common in the future as a consequence of increased glacier and slope instability caused by human induced climate change ice avalanches therefore likely constitute a significant geologic hazard in the near future

february 2003 marine atmospheric conditions and the bora over the northern adriatic 1 a winter oceanographic field experiment provided an opportunity to examine the atmospheric marine conditions over the northern adriatic mean february winds are from a northeasterly direction over most of the adriatic and a more northerly direction along the western coast wind speeds are fastest in jets over the ne coast during bora events and weakest in the mid northwestern adriatic diurnal air temperature cycles are smallest on the ne coast and largest in the midwestern adriatic the maximum sea air difference is 10 c on the eastern coast and near zero on the midwestern adriatic boras are northeasterly from wind events that sweep off croatia and slovenia bringing slightly colder and drier air over the northern adriatic the main bora season is december to march winter 2002 2003 was normal for bora events synoptic scale temporal variations are correlated over the northern adriatic fastest bora winds and highest wind stress over the northern adriatic is concentrated in four topographically controlled jets the strongest is the senj jet while the trieste jet extends across the entire northern adriatic between each two jets is a weak wind zone the greatest mean net heat loss is in bora jets in the ne adriatic where it was 438 w m 2 and is weakest in the midwestern northern adriatic where it was near zero wind stress is concentrated over the ne half of adriatic in four bora jets while wind stress is weak in the nw adriatic there is significant variation in wind stress mean and standard deviation structure over the northern adriatic with each bora event

rheological constraints on martian landslides we use a dynamic finite difference model to simulate martian landslides in the valles marineris canyon system and olympus mons aureole using three different modal rheologies frictional bingham and power law the frictional and bingham modes are applied individually fluidized rheology is treated as a combination of frictional and power law modes general fluidization can include pore pressure contributions whereas acoustic fluidization does not we find that general fluidization most often produces slides that best match landslide geometry in the valles marineris this implies that some amount of supporting liquid or gas was present in the material during failure the profile of the olympus mons aureole is not well matched by any landslide model suggesting an alternative genesis in contrast acoustic fluidization produces the best match for a lunar slide a result anticipated for dry crust with no overlying atmosphere the presence of pressurized fluid during valles marineris landsliding may be due to liquid water beneath a thin cryosphere 1 2 km or flash sublimation of co2

entrainment of debris in rock avalanches an analysis of a long run out mechanism many rock avalanches entrain and liquefy saturated soil from their paths evidence for this includes mud displaced from the margins of rock avalanche deposits substrate material smeared along the base of deposits extrusion of liquefied soil upward through the deposits and increases of volume a hypothesis first suggested in 1881 and since reinforced by several authors suggests that entrainment of substrate material increases mobility although the process has been discussed in the literature for more than 100 years few detailed and quantitative descriptions exist the main purpose of this paper is to describe two recent cases from british columbia canada where rockslides entrained substrate on a very large scale influencing the character of the events estimated volume balance curves based on detailed field mapping are provided for both cases dynamic analyses are carried out using a numerical model and using the same set of rheological parameters the mechanism of material entrainment and displacement is discussed the data suggest that rapid rock failures entraining very large quantities of saturated substrate material represent a special type of landslide transitional between rock avalanche and debris avalanche many rock avalanches can thus be seen as end members of a continuum of phenomena involving rock failure followed by interaction with saturated substrate

runout of the socompa volcanic debris avalanche chile a mechanical explanation for low basal shear resistance we propose a mechanical explanation for the low basal shear resistance about 50 kpa previously used to simulate successfully the complex well documented deposit morphology and lithological distribution produced by emplacement of the 25 km3 socompa volcanic debris avalanche deposit chile stratigraphic evidence for intense basal comminution indicates the occurrence of dynamic rock fragmentation in the basal region of this large granular mass flow and we show that such fragmentation generates a basal shear stress retarding motion of the avalanche that is a function of the flow thickness and intact rock strength the topography of the socompa deposit is realistically simulated using this fragmentation derived resistance function basal fragmentation is also compatible with the evidence from the deposit that reflection of the avalanche from topography caused a secondary wave that interacted with the primary flow

nature of stress accommodation in sheared granular material insights from 3d numerical modeling active faults often contain distinct accumulations of granular wear material during shear this granular material accommodates stress and strain in a heterogeneous manner that may influence fault stability we present new work to visualize the nature of contact force distributions during 3d granular shear our 3d discrete numerical models consist of granular layers subjected to normal loading and direct shear where gouge particles are simulated by individual spheres interacting at points of contact according to simple laws during shear we observe the transient microscopic processes and resulting macroscopic mechanical behavior that emerge from interactions of thousands of particles we track particle translations and contact forces to determine the nature of internal stress accommodation with accumulated slip for different initial configurations we view model outputs using novel 3d visualization techniques our results highlight the prevalence of transient directed contact force networks that preferentially transmit enhanced stresses across our granular layers we demonstrate that particle size distribution psd controls the nature of the force networks models having a narrow i e relatively uniform psd exhibit discrete pipe like force clusters with a dominant and focussed orientation oblique to but in the plane of shear wider psd models e g power law size distributions d 2 6 also show a directed contact force network oblique to shear but enjoy a wider range of orientations and show more out of plane linkages perpendicular to shear macroscopic friction level is insensitive to these distinct force network morphologies however force network evolution appears to be linked to fluctuations in macroscopic friction our results are consistent with predictions based on recent laboratory observations that force network morphologies are sensitive to grain characteristics such as particle size distribution of a sheared granular layer our numerical approach offers the potential to investigate correlations between contact force geometry evolution and resulting macroscopic friction thus allowing us to explore ideas that heterogeneous force distributions in gouge material may exert an important control on fault stability and hence the seismic potential of active faults 2007 elsevier b v all rights reserved

recent climatic change and catastrophic geomorphic processes in mountain environments climatic warming during the last 100 150 years has resulted in a significant glacier ice loss from mountainous areas of the world certain natural processes which pose hazards to people and development in these areas have accelerated as a result of this recent deglaciation these include glacier avalanches landslides and slope instability caused by glacier debuttressing and outburst floods from moraine and glacier dammed lakes in addition changes in sediment and water supply induced by climatic warming and glacier retreat have altered channel and floodplain patterns of rivers draining high mountain ranges the perturbation of natural processes operating in mountain environments caused by recent climatic warming ranges from tens of decades for moraine dam failures to hundreds of years or more for landslides the recognition that climatic change as modest as that of the last century can perturb natural alpine processes has important implications for hazard assessment and future development in mountains even so these effects are probably at least an order of magnitude smaller than those associated with late pleistocene deglaciation ca 15 000 to 10 000 years ago

evaluation of aster and srtm dem data for lahar modeling a case study on lahars from popocatepetl volcano mexico abstract lahars are among the most serious and far reaching volcanic hazards in regions with potential interactions of lahars with populated areas and human structures the assessment of the related hazards is crucial for undertaking appropriate mitigating actions and reduce the associated risks modeling of lahars has become an important tool in such assessments in particular where the geologic record of past events is insufficient mass flow modeling strongly relies on digital terrain data availability of digital elevation models dems however is often limited and thus an obstacle to lahar modeling remote sensing technology has now opened new perspectives in generating dems in this study we evaluate the feasibility of dems derived from the advanced spaceborne thermal emission and reflection radiometer aster and the shuttle radar topography mission srtm for lahar modeling on popocatepetl volcano mexico two gis based models are used for lahar modeling laharz and a flow routing based debris flow model modified single flow direction model msf both predicting areas potentially affected by lahars results of the lahar modeling show that both the aster and srtm dems are basically suitable for use with laharz and msf flow path prediction is found to be more reliable with srtm data though with a coarser spatial resolution errors of the aster dem affecting the prediction of flow paths due to the sensor geometry are associated with deeply incised gorges with north facing slopes laharz is more sensitive to errors of the aster dem than the msf model lahar modeling with the aster dem results in a more finely spaced predicted inundation area but does not add any significant information in comparison with the srtm dem lahars at popocatepetl are modeled with volumes of 1 10 5 to 8 10 6 m 3 based on ice melt scenarios of the glaciers on top of the volcano and data on recent and historical lahar events as regards recently observed lahars the travel distance of lahars of corresponding volume modeled with laharz falls short by 2 to 4 km an important finding is that the travel distance of potential lahar events modeled with laharz may differ by about 2 km when using srtm or aster data because of varying lateral flow volume distribution as a consequence verification and sensitivity analysis of the dem is fundamental to deriving hazard maps from predicted modeled inundation areas because of the global coverage of this type of remote sensing data the conclusion that both srtm and aster derived dems are feasible for lahar modeling opens a wide field of application in volcanic hazards studies

monitoring and modeling ice rock avalanches from ice capped volcanoes a case study of frequent large avalanches on iliamna volcano alaska abstract iliamna is an andesitic stratovolcano of the aleutian arc with regular gas and steam emissions and mantled by several large glaciers iliamna volcano exhibits an unusual combination of frequent and large ice rock avalanches in the order of 1 10 6 m 3 to 3 10 7 m 3 with recent return periods of 2 4 years we have reconstructed an avalanche event record for the past 45 years that indicates iliamna avalanches occur at higher frequency at a given magnitude than other mass failures in volcanic and alpine environments iliamna volcano is thus an ideal site to study such mass failures and its relation to volcanic activity in this study we present different methods that fit into a concept of 1 long term monitoring 2 early warning and 3 event documentation and analysis of ice rock avalanches on ice capped active volcanoes long term monitoring methods include seismic signal analysis and space and airborne observations landsat and aster satellite data was used to study the extent of hydrothermally altered rocks and surface thermal anomalies at the summit region of iliamna subpixel heat source calculation for the summit regions where avalanches initiate yielded temperatures of 307 to 613 k assuming heat source areas of 1000 to 25 m 2 respectively indicating strong convective heat flux processes such heat flow causes ice melting conditions and is thus likely to reduce the strength at the base of the glacier we furthermore demonstrate typical seismic records of iliamna avalanches with rarely observed precursory signals up to two hours prior to failure and show how such signals could be used for a multi stage avalanche warning system in the future for event analysis and documentation space and airborne observations and seismic records in combination with srtm and aster derived terrain data allowed us to reconstruct avalanche dynamics and to identify remarkably similar failure and propagation mechanisms of iliamna avalanches for the past 45 years simple avalanche flow modeling was able to reasonably replicate iliamna avalanches and can thus be applied for hazard assessments hazards at iliamna volcano are low due to its remote location however we emphasize the transfer potential of the methods presented here to other ice capped volcanoes with much higher hazards such as those in the cascades or the andes

large landslides and their effect on sediment flux in south westland new zealand landslides and runoff are dominant erosional agents in the tectonically active alpine south westland area of new zealand characterized by high uplift rates and extreme orographic precipitation despite a high density of shallow debris slides and flows the geomorphic imprints of deep seated bedrock failures are dominant and persistent over 50 large 1k m 2 landslides comprising rock slide avalanches complex rotational and rock block slides wedge failures and deep seated gravitational slope deformation were detected on air photos and shaded relief images major long term impacts on alpine rivers include 1 forced alluviation upstream of landslide dams 2 occlusion of gorges and triggering of secondary riparian landslides and 3 diversion of channels around deposits to form incised meandering gorges remnants of large prehistoric i e pre 1840 landslide deposits possibly represent the low frequency in terms of total area affected yet dominant end of the spectrum of mass wasting in the western southern alps this is at odds with high erosion rates in an active erosional landscape large landslides appear to have dual roles of supplying and retaining sediment the implications of these roles are that 1 previous models of shallow landslide derived sediment flux need to be recalibrated and 2 geomorphic effects of earthquake induced landsliding may persist for at least 10 2 years copyright 2005 john

momentum transfer and friction in the debris of rock avalanches when a mass of loose dry purely frictional material slides down an incline after release at a given velocity the runout the distance the centre of gravity of the displaced mass moves from its initial position depends on momentum transfer within the mass this can be estimated from the profile of the debris accumulation which also allows more accurate calculation of apparent angles of sliding friction in rockfall avalanches the apparent extreme mobility of the elm and frank slides typical rockfall avalanches is explained by momentum transfer in a loose dry purely frictional material with an angle of friction of 30 key words mass wasting momentum transfer landslide accumulation rock avalanche runout distance

large scale landslide simulations global deformation velocities and basal friction the cause of the apparent small friction exhibited by long runout landslides has long been speculated upon in an attempt to provide some insight into the matter this paper describes results obtained from a discrete particle computer simulation of landslides composed of up to 1 000 000 two dimensional discs while simplified the results show many of the characteristics of field data the volumetric effect on runout preserved strata etc and with allowances made for the two dimensional nature of the simulation the runouts compare well with those of actual landslides the results challenge the current view that landslides travel as a nearly solid block riding atop a low friction basal layer instead they show that the mass is completely shearing and indicate that the apparent friction coefficient is an increasing function of shear rate the volumetric effect can then be understood with all other conditions being equal different size slides appear to travel with nearly the same average velocity however as the larger landslides are thicker they experience smaller shear rates and correspondingly smaller fractional resistance

interactions between rock avalanches and glaciers in the mont blanc massif during the late holocene rock avalanches are common in the mont blanc massif which is bordered by valleys with large resident and tourist populations and important highways this paper combines historical data with detailed geomorphological mapping stratigraphic observation and absolute and relative dating to interpret several deposits resulting from rock avalanching onto glaciers nineteen rock falls and rock avalanches are described ranging in volume from 10 000 m3 to 10 106 m3 they occurred between 2500 bp and ad 2007 at six sites the events at three sites miage and drus glaciers and tour des grandes jorasses are characterised by short travel distances those at brenva triolet and frebouge glaciers exhibit excessive travel distances interactions between rock avalanches and glaciers are of four types i rock avalanche triggering where glacial and paraglacial controls include debuttressing of rockwalls due to glacier thinning and retreat oversteepening of rock slopes by glacial erosion and effects of glaciers on permafrost ii rock avalanche mobility in which mobility and travel distance are modified by channelling of rock avalanche debris by moraines and valleys incorporation of ice and snow often 50 for large events and irregularities on the glacier surface iii deposit sedimentology where melting of incorporated ice transforms the final deposit by reducing its thickness typically to 5 m and debris of variable thicknesses is juxtaposed in a hummocky deposit with chaotic piles of angular rock debris and iv glacier dynamics where insulating debris deposited upon a glacier produces a debris covered glacier of different dynamics and high elevated scars can favour the formation of small glaciers

the kolka karmadon rock ice slide of 20 september 2002 an extraordinary event of historical dimensions in north ossetia russian caucasus on 20 september 2002 an enormous rock ice slide and subsequent mud flow occurred on the northern slope of the kazbek massif northern ossetia russian caucasus it started on the north northeast wall of dzhimarai khokh 4780 ma s l and seriously affected the valley of genaldon karmadon immediate governmental actions available scientific information first reconstructions hazard assessments and monitoring activities as well as initial expert judgments recommendations are documented in order to enable more detailed analyses and modelling of the event by the wider scientific community among the most remarkable aspects related to this event are 1 the relation between the recent event and somewhat smaller but quite similar events that occurred earlier in historical times 1835 1902 2 the interactions between unstable local geological structures and complex geothermal and hydraulic conditions in the starting zone with permafrost cold to polythermal hanging glaciers and volcanic effects hot springs in close contact with each other 3 the erosion and incorporation of a debris covered valley glacier largely enhancing the sliding volume of rocks ice firn snow water and probably air to a total of about 100 106m3 and 4 the astonishingly high flow velocities up to 300 km h 1 and enormous length of travel path 18 km plus 15 km of debris mud flow this extraordinary case illustrates that large catastrophic events in high mountain regions typically involve a multitude of factors and require integrated consideration of complex chains of processes a task which must be undertaken by qualified groups of experts

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

pseudotachylyte frictionite at the base of the arequipa volcanic landslide deposit peru implications for emplacement mechanisms abstract the arequipa volcanic landslide deposit peru displays a pseudotachylyte or frictionite at its basal contact with an older ignimbrite the pseudotachylyte consists of a dark 1 cm thick vitreous layer that shows striations on its upper surface it contains small mineral clasts from both the landslide rocks and the underlying ignimbrite embedded in an optically isotropic matrix tem observations revealed a clast melt suspension with a lower black obsidian like vein made of chemically heterogeneous glass the pseudotachylyte is interpreted as the result of partial melting due to frictional heating during landslide emplacement this is the third pseudotachylyte reported at the base of a landslide deposit and the first in a volcanic environment calculations show that basal melting only accounts for a small proportion of the total energy released during landslide emplacement indicating that landslide transport was dominated by dissipative stresses affecting the whole landslide body and not conce

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

runout of dry granular avalanches laboratory experiments on granular avalanching of dry sands and gravels reveal a consistent pattern of runout distance varying with fall height fall slope and volume of material for volumes rangi

evaluating titan2d mass flow model using the 1963 little tahoma peak avalanches mount rainier washington the titan2d geophysical mass flow model is evaluated by comparing its simulation results and those obtained from another flow model flow3d with published data on the 1963 little tahoma peak avalanches on mount rainier washington the avalanches totaling approximately 10 10 6 m 3 of broken lava blocks and other debris traveled 6 8 km horizontally and fell 1 8 km vertically h l 0 246 velocities calculated from runup range from 24 to 42 m s and may have been as high as 130 m s while the avalanches passed over emmons glacier titan2d is a code for an incompressible coulomb continuum it is a depth averaged dshallow watert granular flow model the conservation equations for mass and momentum are solved with a coulomb type friction term at the basal interface the governing equations are solved on multiple processors using a parallel adaptive mesh godunov scheme adaptive gridding dynamically concentrates computing power in regions of special interest mesh refinement and coarsening key on the perimeter of the moving avalanche the model flow initiates as a pile defined as an ellipsoid by a height z and an elliptical base defined by radii in the x and y planes flow parameters are the internal friction angle and bed friction angle results from the model are similar in terms of velocity history lateral spreading location of runup areas and final distribution of the little tahoma peak deposit the avalanches passed over the emmons glacier along their upper flow paths but lower in the valley they traversed stream gravels and glacial outwash deposits this presents difficulty in assigning an appropriate bed friction angle for the entire deposit incorporation of variable bed friction angles into the model using gis will help to resolve this issue d 2004 elsevier b v all rights reserved

unraveling driving factors for large rock ice avalanche mobility large rock ice avalanches have attracted attention from scientists for decades and some of these events have caused high numbers of fatalities a relation between rock slope instabilities in cold high mountain areas and climate change is currently becoming more evident and questions about possible consequences and hazard scenarios in densely populated high mountain regions leading beyond historical precedence are rising to improve hazard assessment of potential rock ice avalanches their mobility is a critical factor this contribution is an attempt to unravel driving factors for the mobility of large rock ice avalanches by synthesizing results from physical laboratory experiments and empirical data from 64 rock ice avalanches with volumes 1x106 m3 from glacierized high mountain regions around the world the influence of avalanche volume water and ice content low friction surfaces and topography on the apparent coefficient of friction as a measure of mobility is assessed in laboratory experiments granular ice in the moving mass was found to reduce bulk friction up to 20 while water led to a reduction around 50 for completely saturated material compared with dry flows evidence for the effects of water as a key driving factor to enhance mobility was also found in the empirical data while the influence of the ice content could not be confirmed to be of much relevance in nature besides liquefaction it was confirmed that mobility increases with volumes and that frictional surface characteristics such as flow paths over glaciers are also dominant variables determining mass movement mobility effects of the topography along the flow path as well as channeling are assumed to be other critical factors the results provide an empirical basis to roughly account for different path and flow characteristics of large rock ice avalanches and to find appropriate ranges for friction parameters for scenario modeling and hazard assessments copyright 2011 john wiley sons ltd

topography and volume effects on travel distance of surface failure the authors investigated factors affecting the travel distance of a surface failure and developed a simple model for estimating the distance based on soil properties and topographic factor the authors conducted field surveys and various soil tests for a number of surface failures that occurred during torrential rain at the end of august 1998 in southern fukushima prefecture japan the authors studied the effects of various factors such as landslide volume pore water pressure slope inclination and the internal friction near the slip surfaces on the travel distances the analyses showed no clear relationship between landslide volume and equivalent coefficient of friction which was likely attributable to the very small range of volume compared to other studies on catastrophic landslides the effect of excess pore water pressure was likely negligible because undrained conditions were not to be maintained at the shallow flow depths a positive correlation was shown between slope inclination and equivalent coefficient of friction this correlation was attributable to two factors one was positive correlation between the internal friction on the slip surface and slope inclination and the other was the kinetic energy dissipation of moving mass that occurred at the inclination changing point between a slope and a sedimentary flat surface the authors then developed a predictive model for critical flow inclination of landslide by installing the factors of soil properties and slope inclination factors the model predicted equivalent coefficient of frictions which were very similar to the observed values thus verifying the effectiveness of the model

new geophysical insight into the dynamics of stromboli volcano italy abstract a 56 hour gravity sequence recorded in the crater area of stromboli volcano is presented data were acquired during a period of normal strombolian activity high frequency gravity anomalies up to 20 gal t tens of seconds are observed comparison with independent data reveals that these changes reflect the response of the gravimeter excited by seismic waves during strombolian explosions correlated changes in the energy distribution over time appear in the continuous wavelet transforms of gravity and rms tremor but over different scales corresponding to periods centered at about 50 and 25 min for gravity and tremor respectively we infer that the rate of fresh magma supply to the shallow feeding system controls the energy distribution over time of the coupled components in gravity and rms tremor signals in particular the gravity signal with an average amplitude of 1 2 gal could be induced by temporary accumulations at shallow depth of the volatiles discharged by quiescent degassing changes in the rate of explosions from the summit craters correlate with changes in the amplitude of the coupled gravity and volcanic tremor oscillations implying that even though the slug genesis process behind the explosions occurs at deeper levels it is also controlled by the rate of gas rich magma supply from below negative gravity anomalies of about 20 gal over intervals of some hours are also observed separated by intervals of about 24 h they could be induced by increases in magma vesicularity in the uppermost part of the conduit plexus a view supported by i changes in the time space distribution of tremor amplitudes and ii increases in spattering activity from a summit vent both occurring during the development of the negative gravity anomalies the processes behind mild strombolian explosions do not trigger measurable gravity changes nevertheless the slug ascent before a major explosion could induce a precursory gravity signal

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

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

rock avalanches on a glacier and morainic complex in haut val ferret mont blanc massif italy abstract deposits in upper val ferret mont blanc massif italy have been attributed to glacier advances and to a rock avalanche of 12 september ad 1717 we review evidence for the timing and mode of emplacement of the deposit and present a new geomorphic interpretation and relative and absolute dating to show that the ad 1717 deposit is less extensive than previously thought the landslide was deflected along one side of the valley floor preserving older slope and morainic sediments along the other side an earlier rock avalanche onto the triolet glacier occurred before ad 1000 the deposits of these landslides partly cover older moraine several kilometres downstream from the present glacier front and have affected the glacier regimen and construction of its moraines this study highlights the geomorphic impact of rock avalanches in glacierized high mountains