elevation changes of ice caps in the canadian arctic archipelago 1 precise repeat airborne laser surveys were conducted over the major ice caps in the canadian arctic archipelago in the spring of 1995 and 2000 in order to measure elevation changes in the region our measurements reveal thinning at lower elevations below 1600 m on most of the ice caps and glaciers but either very little change or thickening at higher elevations in the ice cap accumulation zones recent increases in precipitation in the area can account for the slight thickening where it was observed but not for the thinning at lower elevations for the northern ice caps on the queen elizabeth islands thinning was generally 0 5 m yr 1 which is consistent with what would be expected from the warm temperature anomalies in the region for the 5 year period between surveys and appears to be a continuation of a trend that began in the mid 1980s farther south however on the barnes and penny ice caps on baffin island this thinning was much more pronounced at over 1 m yr 1 in the lower elevations here temperature anomalies were very small and the thinning at low elevations far exceeds any associated enhanced ablation the observations on barnes and perhaps penny are consistent with the idea that the observed thinning is part of a much longer term deglaciation as has been previously suggested for barnes ice cap on the basis of the regional relationships between elevation and elevation change in our data the 1995 2000 mass balance for the archipelago is estimated to be 25 km3 yr 1 of ice which corresponds to a sea level increase of 0 064 mm yr 1 this places it among the more significant sources of eustatic sea level rise though not as substantial as the greenland ice sheet alaskan glaciers or the patagonian ice fields

spatially integrated geodetic glacier mass balance and its uncertainty based on geostatistical analysis application to the western svartisen ice cap norway estimates of glacier mass balance using geodetic methods can differ significantly from estimates using direct glaciological field based measurements to determine if such differences are real or methodological there is a need to improve uncertainty estimates in both methods in this paper we focus on the uncertainty of geodetic methods and describe a geostatistical technique that takes into account the spatial correlation of the elevation differences when calculating spatially averaged elevation changes we apply this method to the western svartisen ice cap norway using elevation differences from the surrounding bedrock derived from stereophotogrammetry we show that the uncertainty is not only dependent on the standard error of the individual elevation differences but is also dependent on the size of the averaging area and the scale of the spatial correlation to assess if the geostatistical analysis made over bedrock is applicable to glacier surfaces we use concurrent photogrammetrical and laser scanning data from bedrock and a range of glacier surfaces to evaluate the dependency of the geostatistical analysis on the surface type the estimated geodetic mass balance and its uncertainty is 2 6 0 9 m w e for the period 1968 85 and 2 0 2 2 m w e for 1985 2002

topographic controls on the surface energy balance of a high arctic valley glacier 1 this paper presents the results of a distributed two dimensional surface energy balance model used to investigate the spatial and temporal variations in the surface energy balance of midre lovenbreen a small valley glacier in northwest spitsbergen svalbard over the summer of 2000 we utilize high resolution airborne lidar data to derive a digital elevation model of the glacier and surrounding topography on which a surface energy balance is computed driven by meteorological data obtained from a meteorological station located on the glacier and a synoptic station maintained at the nearby ny alesund research base given the high resolution topographic data we focus particularly on whether the long duration of sunshine at high latitudes compensates for the higher solar zenith angles on the season long energy balance and whether shading by the surrounding topography plus glacier surface slope and aspect play an increased role in the patterns of solar radiation receipt and hence melt over the glacier surface the model results are validated using a combination of mass balance data from the glacier measured surface lowering at the glacier meteorological station and by comparing a derived energy balance component from the model with a measured energy flux overall the model performance is very good glacier topography is found to play a fundamental role in determining the surface energy balance topographic shading slope and aspect and correction of the surface albedo for high solar zenith angles are found to play a crucial role in determining spatial patterns of surface energy balance and therefore melt

quantifying tropospheric volcanic emissions with airs the 2002 eruption of mt etna italy 1 the atmospheric infrared sounder airs is a hyperspectral ir spectrometer orbiting on the eos aqua spacecraft since may 2002 in late october 2002 airs detected lower tropospheric sulfur dioxide and ash emitted by an eruption of mt etna italy in plumes which could be tracked over 1000 km from the volcano into north africa we report retrievals of so2 and ash column amounts and ash particle size in the etna plumes airs total so2 compares favorably with contemporaneous ground based correlation spectrometry cospec measurements retrieval of ash cloud parameters in the eruption plumes permits quantitative studies of distal ash fallout the etna data demonstrate the potential of airs to improve measurements of volcanic so2 and ash loading in the troposphere and to refine our understanding of volcanic cloud composition structure and evolution

recent volume and area changes of kaskawulsh glacier yukon canada recent surface elevation changes of kaskawulsh glacier yukon canada are quantified by comparing an air photo derived dem from 1977 and airborne lidar measurements from 1995 2000 and 2007 surface area changes are assessed using historical aerial photography from 1956 and satellite imagery from 1977 to 2007 combined these measurements provide some of the first detailed records of volume change of a large yukon glacier between 1977 and 2007 kaskawulsh glacier underwent a decrease in area of 1 53 and a decrease in volume of 3 27 5 94 km 3 w e the terminus also retreated by 655 m over the period 1956 2007 there was relatively minor volume change over the period 1977 95 0 01 km 3 w e a 1 while over the periods 1995 2000 and 2000 07 volume losses occurred at a relatively constant rate of 0 51 and 0 50 km 3 a 1 w e respectively since 1995 thinning has been prominent throughout the ablation zone while relative stability and even slight thickening has occurred in the accumulation zone these findings are similar to those recently observed at other nearby alaskan glaciers

the formation and failure of natural dams of the numerous kinds of dams that form by natural processes dams formed from landslides glacial ice and late neoglacial moraines present the greatest threat to people and property landslide dams form in a wide range of physiographic settings the most common types of mass movements that form landslide dams are rock and debris avalanches rock and soil slumps and slides and mud debris and earth flows the most common initiation mechanisms for dam forming landslides are excessive rainfall and snowmelt and earthquakes landslide dams can be classified into six categories based on their relation with the valley floor type i dams 11 of 184 landslide dams from around the world that we were able to classify do not reach from one valley side to the other type ii dams 44 span the entire valley floor in some cases depositing material high on opposite valley sides type iii dams 41 move considerable distances both upstream and downstream from the landslide failure type iv dams 1 are rare and involve the contemporaneous failure of material from both sides of a valley type v dams 1 also are rare and are created when a single landslide sends multiple tongues of debris into a valley and forms two or more landslide dams in the same reach of river type vi dams 3 involve one or more failure surfaces that extend under the stream or valley and emerge on the opposite valley side many landslide dams fail shortly after formation in our sample of 73 documented landslide dam failures 27 of the landslide dams failed less than 1 day after formation and about 50 failed within 10 days over topping is by far the most common cause of failure the timing of failure and the magnitude of the resulting floods are controlled by dam size and geometry material characteristics of the blockage rate of inflow to the impoundment size and depth of the impoundment bedrock control of flow and engineering controls such as artificial spill ways diversions tunnels and planned breaching by blasting or conventional excavation glacial ice dams can produce at least nine kinds of ice dammed lakes the most dangerous are lakes formed in main valleys dammed by tributary glaciers failure can occur by erosion of a drainage tunnel under or through the ice dam or by a channel over the ice dam cold polar ice dams generally drain supraglacially or marginally by downmelting of an outlet channel warmer temperate ice dams tend to fail by sudden englacial or subglacial breaching and drainage late neoglacial moraine dammed lakes are located in steep mountain areas affected by the advances and retreats of valley glaciers in the last several centuries these late neoglacial dams pose hazards because 1 they are sufficiently young that vegetation has not stabilized their slopes 2 many dam faces are steeper than the angle of repose 3 these dams and lakes are immediately downslope from steep crevassed glaciers and near vertical rock slopes and 4 downstream from these dams are steep canyons with easily erodible materials that can be incorporated in the flow and increase flood peaks the most common reported failure mechanism is overtopping and breaching by a wave or series of waves in the lake generated by icefalls rockfalls or snow or rock avalanches melting of ice cores or frozen ground and piping and seepage are other possible failure mechanisms natural dams may cause upstream flooding as the lake rises and downstream flooding as a result of failure of the dam although data are few for the same potential energy at the dam site ownstream flood peaks from the failure of glacier ice dams are smaller than those from landslide moraine and structed earth fill and rock fill dam failures moraine dam failures appear to produce some of the largest downstream flood peaks for potential energy at the dam site greater than 1011 1012 joules differences in flood peaks natural dam failures appear to be controlled by dam characteristics and failure mechanisms

dem quality assessment for quantification of glacier surface change photogrammetric digital elevation models dems are often used to derive and monitor surfaces in inaccessible areas they have been used to monitor the spatial and temporal change of glacier surfaces in order to assess glacier response to climate change however deriving photo grammetric dems of steep mountainous topography where the surface is often obscured by regions of deep shadow and snow is particularly difficult assessing the quality of the derived surface can also be problematic as high accuracy ground control points may be limited and poorly distributed throughout the modelled area we present a method of assessing the quality of a derived surface through a detailed sensitivity analysis of the dem collection parameters through a multiple input failure warning model mifwm the variance of a dem cell elevation is taken as an indicator of surface reliability allowing potentially unreliable areas to be excluded from further analysis this analysis allows the user to place greater confidence in the remaining dem an example of this method is presented for a small mountain glacier in svalbard and the mifwm is shown to label as unreliable more dem cells over the entire dem area but fewer over the glacier surface than other methods of data quality assessment the mifwm is shown to be an effective and easily used method for assessing dem surface quality

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

discrete element simulation of the jiufengershan rock and soil avalanche triggered by the 1999 chi chi earthquake taiwan we present contact dynamics discrete element simulations of the earthquake triggered jiufengershan avalanche which mobilized a 60 m thick 1 5 km long sedimentary layer dipping similar to 22 degrees se toward a valley the dynamic behavior of the avalanche is simulated under different assumptions about rock behavior water table height and boundary shear strength additionally seismic shaking is introduced using strong motion records from nearby stations we assume that seismic shaking generates shearing and frictional heating along the surface of rupture which in turn may induce dynamic weakening and avalanche triggering a simple slip weakening criterion was adopted to simulate shear strength drop along the rupture surface we investigate the mechanical processes occurring during triggering and propagation of an avalanche mobilizing shallowly dipping layers incipient deformation forms a pop up structure at the toe of the dip slope as the avalanche propagates the pop up deforms into an overturned fold which overrides the surface of separation along a decollement simultaneously uphill layers slide at high velocity 125 km h and are folded and disrupted as they reach the toe of the dip slope the avalanche foot forms a wedge that is pushed forward as deformed rocks accrete at its rear we simulated five cross sections across the jiufengershan avalanche which differ in the geometry of the surface of separation topographic and simulated surface profiles are similar the friction coefficient at the surface of separation determined from back analysis is abnormally low mu ss 0 2 possibly due to lubrication by liquefied soils the granular deposits of simulated earthquake and rain triggered avalanches are similar

discrete element modeling of the mass movement and loose material supplying the gully process of a debris avalanche in the bayi gully southwest china abstract the dynamic process of a debris avalanche in mountainous areas is influenced by the landslide volume topographical conditions mass material composition mechanical properties and other factors a good understanding of the mass movement and loose material supplying the gully process is very important for understanding the dynamic properties of debris avalanches three dimensional particle flow code pfc3d was used to simulate a debris avalanche in quaternary deposits at the bayi gully southwest china fortran and autocad were used for the secondary development to display the mass movement process and to quantitatively describe the mass movement and loose material supplying the gully process the simulated results show that after the landslide is initiated the gravitational potential energy is converted into kinetic energy with a variation velocity for the sliding masses two stages exist for the average movement velocity the acceleration stage and the slowdown stage which are influenced by the topographical conditions for the loose materials supplying the gully process the cumulative volume of the sliding masses into the gully gradually increases over the time when the landslide volume is not large enough the increasing landslide volume does not obviously influence the movement process of the sliding masses the travel distance and movement velocity increase with the decreasing numerical parameters and the mass movement process is finished more quickly using low value parameters the deposition area of the sliding masses decreases with the increasing numerical parameters and the corresponding deposition thickness increases the mass movement of the debris avalanche is not only influenced by the mechanical parameters but is also controlled by the topographical conditions

elevation changes measured during 1966 2010 on the monsoonal temperate glaciers ablation region gongga mountains china abstract temperate glaciers are more sensitive to climate change than are polar or continental glaciers and can drive remarkable runoff variation in local water catchments changes in the glacier area and surface elevation of the three monsoonal temperate glaciers in the gongga mountains china were analyzed using series of remote sensing images and digital elevation model dem data all possible sources of uncertainty were considered in detail the results showed that the total glacier area decreased by 4 3 km 2 6 7 between 1966 and 2010 a comparison of glacier surface elevations using dems derived from dual frequency differential gps dgps surveys in 2010 and from 1966 to 1989 from topographic maps the three glaciers underwent significant mass loss from 1966 to 2010 and the mean surface elevation changes were 0 90 0 45 m y 1 06 0 45 m y and 1 12 0 45 m y for hailuogou hlg dagongba dgb and yanzigou yzg glaciers respectively from 1966 to 2010 analysis of the meteorological data showed that the mean annual air temperature increase was the main reason for the thinning and volume loss thinning of the glacier tongue and volume loss was more intense in the period 1989 2010 than in 1966 89 debris thickness and other factors are also believed to play important roles in differential thinning among different areas and periods

transient water and sediment storage of the decaying landslide dams induced by the 2008 wenchuan earthquake china article earthquake triggered landslide dams are potentially dangerous disrupters of water and sediment flux in mountain rivers and capable of releasing catastrophic outburst flows to downstream areas we analyze an inventory of 828 landslide dams in the longmen shan mountains china triggered by the mw 7 9 2008 wenchuan earthquake this database is unique in that it is the largest of its kind attributable to a single regional scale triggering event 501 of the spatially clustered landslides fully blocked rivers while the remainder only partially obstructed or diverted channels in steep watersheds of the hanging wall of the yingxiu beichuan fault zone the size distributions of the earthquake triggered landslides landslide dams and associated lakes a can be modeled by an inverse gamma distribution b show that moderate size slope failures caused the majority of blockages and c allow a detailed assessment of seismically induced river blockage effects on regional water and sediment storage monte carlo simulations based on volumetric scaling relationships for soil and bedrock failures respectively indicate that 14 18 of the estimated total coseismic landslide volume of 6 4 14 6 10 9 m 3 was contained in landslide dams representing only 1 4 of the 60 000 slope failures attributed to the earthquake these dams have created storage capacity of 0 6 10 9 m 3 for incoming water and sediment about 25 of the dams containing 2 of the total river blocking debris volume failed one week after the earthquake these figures had risen to 60 20 and 90 90 within one month and one year respectively thus also emptying 92 of the total potential water and sediment storage behind these dams within one year following the earthquake currently only 0 08 10 9 m 3 remain available as natural reservoirs for storing water and sediment while 0 19 10 9 m 3 i e about a third of the total river blocking debris volume has been eroded by rivers dam volume and upstream catchment area control to first order the longevity of the barriers and bivariate domain plots are consistent with the observation that most earthquake triggered landslide dams were ephemeral we conclude that the river blocking portion of coseismic slope failures disproportionately modulates the post seismic sediment flux in the longmen shan on annual to decadal timescales

changes in geometry and subglacial drainage of midre lovenbreen svalbard determined from digital elevation models digital elevation models dems of the bed and surface of the polythermal midre lovenbreen svalbard are used to identify changes in glacier geometry between 1977 and 1995 the calculated mean annual mass balance 0 61 m water equivalent w e a 1 is more negative than that derived from field measurements 0 35 m w e a 1 although the error associated with this value 0 7 m a 1 suggests that the difference may be accounted for by errors however similar discrepancies between dem based and field based measurements of mass balance have been reported elsewhere in svalbard although errors may be responsible patterns of surface elevation change may also be explained in terms of patterns of ablation accumulation and dynamics the theoretical structure of the subglacial drainage system is modelled using different assumptions about subglacial water pressure in 1977 and 1995 these reconstructions are compared with the observed positions of proglacial outlet streams decreasing subglacial water pressure results in a decrease in the influence of surface morphology and an increase in the role of the bed topography on drainage routing which generally leads to more dispersed drainage long term changes in the position of proglacial outlet streams occur as a result of changes in glacier geometry but short term changes may also occur in response to early season water pressures controlled by meteorological and hydrological conditions copyright 2003 john wiley sons ltd

estimating the long term calving flux of kronebreen svalbard from geodetic elevation changes and mass balance modelling this study independently quantifies geodetic elevation change and models surface mass balance to solve the continuity equation the approach is tested on two dynamically different glaciers kongsvegen and kronebreen in northwest svalbard through two time epochs 1966 1990 95 i and 1990 95 2007 ii on kongsvegen a dynamically inactive glacier the residual term represents an error associated with determining elevation changes and surface mass balance it is apparent that centerline mass balance estimates are not representative of the entire glacier which we relate to center line accumulation being larger than the elevation bin average on kronebreen a fast flowing and actively calving glacier a significant part of the residual is identified with the long term calving flux for both glaciers the cumulative surface mass balance remained close to zero during the first epoch but became increasingly negative in the second epoch the long term calving flux of kronebreen is estimated to be 0 14 0 03 km3 w e a 1 during epoch i and 0 20 0 05 km3 w e a 1 in epoch ii

nature and origin of upper crustal seismic velocity fluctuations and associated scaling properties combined stochastic analyses of ktb velocity and lithology logs the main borehole of the german continental deep drilling program ktb extends over 9000 m into a crystalline upper crust consisting primarily of interlayered gneiss and metabasite we present a joint analysis of the velocity and lithology logs in an effort to extract the lithology component of the velocity log covariance analysis of lithology log approximated as a binary series indicates that it may originate from the superposition of two brownian stochastic processes fractal dimension 1 5 with characteristic scales of 2800 m and 150 m respectively covariance analysis of the velocity fluctuations provides evidence for the superposition of four stochastic process with distinct characteristic scales the largest two scales are identical to those derived from the lithology confirming that these scales of velocity heterogeneity are caused by lithology variations the third characteristic scale 20 m also a brownian process is probably related to fracturing based on correlation with the resistivity log the superposition of these three brownian processes closely mimics the commonly observed 1 k decay fractal dimension 2 0 of the velocity power spectrum the smallest scale process characteristic scale 1 7 m requires a low fractal dimension 1 0 and accounts for 60 of the total rms velocity variation a comparison of successive logs from 6900 7140 m depth indicates that such variations are not repeatable and thus probably do not represent true velocity variations in the crust the results of this study resolve disparity between the differing published estimates of seismic heterogeneity based on the ktb sonic logs and bridge the gap between estimates of crustal heterogeneity from geologic maps and borehole logs

contribution of the patagonia icefields of south america to sea level rise digital elevation models of the northern and southern patagonia icefields of south america generated from the 2000 shuttle radar topography mission were compared with earlier cartography to estimate the volume change of the largest 63 glaciers during the period 1968 1975 2000 these glaciers lost ice at a rate equivalent to a sea level rise of 0 042 0 002 millimeters per year in the more recent years 1995 2000 average ice thinning rates have more than doubled to an equivalent sea level rise of 0 105 0 011 millimeters per year the glaciers are thinning more quickly than can be explained by warmer air temperatures and decreased precipitation and their contribution to sea level per unit area is larger than that of alaska glaciers

ice elevations and surface change on the malaspina glacier alaska 1 here we use ice cloud and land elevation satellite icesat derived elevations and surface characteristics to investigate the malaspina glacier of southern alaska although there is significant elevation variability between icesat tracks on this glacier we were able to discern general patterns in surface elevation change by using a regional digital elevation model dem as a reference surface specifically we report elevation differences between icesat laser 1 3 observations february 2003 november 2004 and a shuttle radar topography mission srtm derived dem from february 2000 elevation decreases of up to 20 25 m over a 3 4 year time period were observed across the folded loop moraine on the southern portion of the malaspina glacier

a comparison of seismic and radar methods to establish the thickness and density of glacier snow cover we show that geophysical methods offer an effective means of quantifying snow thickness and density opportunistic efficient but non optimized seismic refraction and ground penetrating radar gpr

optimizing photogrammetric dems for glacier volume change assessment using laser scanning derived ground control points photogrammetric processing of archival stereo imagery offers the opportunity to reconstruct glacier volume changes for regions where no such data exist and to better constrain the contribution to sea level rise from small glaciers and ice caps the ability to derive digital elevation model dem measurements of glacier volume from photogrammetry relies on good quality well distributed ground reference data which may be difficult to acquire this study shows that ground control points gcps can be identified and extracted from point cloud airborne lidar data and used to control photogrammetric glacier models the technique is applied to midtre lovenbreen a small valley glacier in northwest svalbard we show that the amount of ground control measured and the elevation accuracy of gcp coordinates based on known and theoretical error considerations has a significant effect on photogrammetric model statistics dem accuracy and the subsequent geodetic measurement of glacier volume change models controlled with fewer than 20 lidar control points or gcps from sub optimal areas within the swath footprint overestimated volume change by 14 53 over a 2 year period dems derived from models utilizing 20 25 or more gcps however gave volume change estimates within 4 of those from repeat lidar data 0 51 m a 1 between 2003 and 2005 our results have important implications for the measurement of glacier volume change from archival stereo imagery sources

changes in the glacier extent and surface elevation along the ningchan and shuiguan river source eastern qilian mountains china we investigate the changes at nine glaciers in the ningchan and shuiguan river source eastern qilian mountains between 1972 and 2010 according to analysis of topographic maps and multispectral satellite data all nine glaciers in the study area have retreated by a maximum of 250 57 4 m and a minimum of 91 57 4 m the total glacier area decreased by 1 20 km 2 corresponding to 9 9 of the glacierized area in 1972 comparing the two dems generated from the topographic maps and real time kinematic gps data the mean glacier thinning rate was 0 64 m yr 1 between 1972 and 2010 the most significant thinning generally occurred on the termini the ice volume loss was about 106 8 46 7 x 10 3 km 3 equal to 90 8 39 7 x 10 3 km 3 w e which suggested a mean water discharge of 0 1 0 05 m 3 s during 1972 2010 based on analysis of meteorological data the summer temperature june august tends to increase over a similar time period the consistency of temperature increase and glacier shrinkage allows us to suggest that air temperature plays an important role in glacier changes in this region c 2014 university of washington published by elsevier inc all rights reserved

landslide hazard evaluation a review of current techniques and their application in a multi scale study central italy in recent years growing population and expansion of settlements and life lines over hazardous areas have largely increased the impact of natural disasters both in industrialized and developing countries third world countries have difficulty meeting the high costs of controlling natural hazards through major engineering works and rational land use planning industrialized societies are increasingly reluctant to invest money in structural measures that can reduce natural risks hence the new issue is to implement warning systems and land utilization regulations aimed at minimizing the loss of lives and property without investing in long term costly projects of ground stabilization government and research institutions worldwide have long attempted to assess landslide hazard and risks and to portray its spatial distribution in maps several different methods for assessing landslide hazard were proposed or implemented the reliability of these maps and the criteria behind these hazard evaluations are ill formalized or poorly documented geomorphological information remains largely descriptive and subjective it is hence somewhat unsuitable to engineers policy makers or developers when planning land resources and mitigating the effects of geological hazards in the umbria and marche regions of central italy attempts at testing the proficiency and limitations of multivariate statistical techniques and of different methodologies for dividing the territory into suitable areas for landslide hazard assessment have been completed or are in progress at various scales these experiments showed that despite the operational and conceptual limitations landslide hazard assessment may indeed constitute a suitable cost effective aid to land use planning within this framework engineering geomorphology may play a renewed role in assessing areas at high landslide hazard and helping mitigate the associated risk

a view on some hydrological triggering systems in landslides abstract in this paper different types of hydrological triggering systems for debris flows shallow and deeper landslides are described the generation of surface run off and high peak discharges in first order alpine catchments is an important triggering mechanism for debris flows failure conditions in shallow landslides can occur when at a critical depth which is determined by the cohesion of the soil and the slope angle the moisture content in the soil becomes close to saturation resulting in a considerable reduction of soil strength deeper landslides 5 20 m depth are in most cases triggered by positive pore pressures on the slip plane induced by a rising ground water level the assessment of meteorological threshold conditions for shallow landslides 1 2 m needs more detailed meteorological information than for deeper landslides in the analyses of the hydrological triggering systems of deeper landslides the presence of a permeable top layer and fissures has to be taken into consideration

contribution of alaskan glaciers to sea level rise derived from satellite imagery over the last 50 years retreating glaciers and ice caps gic contributed 0 5 mm yr to sea level rises slr and one third is believed to originate from ice masses bordering the gulf of alaska however these estimates of ice wastage in alaska are based on methods that measure a limited number of glaciers and extrapolate the results to estimate ice loss for the many thousands of others how these methods capture the complex pattern of decadal elevation changes at the scale of individual glacier and mountain range is unclear here combining a comprehensive glacier inventory with elevation changes derived from sequential digital elevation models dems we found that between 1962 and 2006 alaskan glaciers lost 41 9 8 6 km 3 yr water equivalent w e and contributed 0 12 0 02 mm yr to slr our ice loss is 34 lower than previous estimates reasons for our lower values include the higher spatial resolution of our glacier inventory and the reduction of ice thinning under debris and at the glacier margins which were not resolved in earlier work estimates of mass loss from gic in other mountain regions could be subject to similar revisions

towards a complete understanding of the triggering mechanism of a large reactivated landslide in the three gorges reservoir abstract the primary aim of this study is to research the characteristics of a slide motion and its relationships with environmental triggers with reference to the quchi landslide which is a large slow moving reactivated landslide in the three gorges reservoir region since 2006 this instability has been involved in a slow moving process with clearly visible signs ground fissures cracking of houses and road the landslide consists of 18 mm3 rock masses threatening quchi town and a road that is crucial for local transportation for civil protection purposes a continuous monitoring system has been put into use since 2009 combining four years of meteorological and hydrological data with gps displacement measurements and in situ observations allows a detailed identification of the key processes involved the deformation is thought to be closely related to precipitations and fluctuating reservoir levels slope movements have a highly distinctive pattern that is characterized by high deformation starting in june and lasting into september when the reservoir level drops and rainfall increases followed by a rapid transition to constant deformation until the next wet season in order to investigate in detail the influences of rainfall and fluctuating water levels on the hydromechanical behavior of the landslide a series of two dimensional numerical simulations are performed using the universal distinct element code udec the modeling reveals that precipitation mainly mobilizes the slope materials on the upper part of the slope while the other trigger factor fluctuating water levels destabilizes the foot of the slope into a multistage failure with a remarkable retrogressive evolution the slide is most likely to collapse in a complex pattern characterized by en masse sliding on the upper part of the slope and a retrogressive rupture at its foot

the determination of statistical and deterministic hydrological landslide triggering thresholds hydrological landslide triggering thresholds separate combinations of daily and antecedent rainfall or of rainfall intensity and duration that triggered landslides from those that failed to trigger landslides they are required for the development of landslide early warning systems when a large data set on rainfall and landslide occurrence is available hydrological triggering thresholds are determined in a statistical way when the data on landslide occurrence is limited deterministic models have to be used for shallow landslides directly triggered by percolating rainfall triggering thresholds can be established by means of one dimensional hydrological models linked to the infinite slope model in the case of relatively deep landslides located in topographic hollows and triggered by a slow accumulation of water at the soil bedrock contact simple correlations between landslide occurrence and rainfall can no longer be established therefore real time failure probabilities have to be determined using hydrological catchment models in combination with the infinite slope model

the mechanism of the 1941 tsaoling landslide taiwan insight from a 2d discrete element simulation tsaoling is located in southwestern taiwan 10 km east of the frontal thrusts of the mountain belt five large historical landslide events were recorded from 1862 to 1999 no details of the earliest landslide event 1862 are available thus this paper deals with the 1941 landslide event using the particle flow code in two dimensions pfc 2d to simulate the mechanism of the tsaoling landslide in 1941 this study shows that the landslide block developed cracks and slid down 0 2 1 8 m on the sliding plane the cracks concentrated in certain zones which corresponded to future landslide detachment planes during the vibration simulation the cracks spread from the shear plane to ground surface monitoring the variations of the displacements velocity and stress during vibration simulation showed that the peak velocity and stress in the transition zones occurred at 3 s the displacement of the left part of the block exceeded 1 3 m and the displacement of the right part was less than 1 3 m during vibration simulation these results suggest that the left part of the block was pushed down by the right part ultimately inducing a landslide during an earthquake

spatio temporal variability in elevation changes of two high arctic valley glaciers uncertainties in estimates of glacier and ice cap contribution to sea level rise exist in part due to poor quantification of mass balance errors particularly those resulting from extrapolation of sparse measurements centre line data are often assumed to be representative of the glacier as a whole with little attention paid to extrapolation errors or their effect on mass balance estimates here we present detailed digital elevation model dem measurements of glacier wide elevation changes over the last 40 years at two glaciers on svalbard norwegian arctic austre broggerbreen and midtre lovenbreen are shown to have lost 27 54 0 98 and 9 65 0 76 10 7 m 3 of ice respectively between 1966 and 2005 findings that we relate to trends in average summer air temperatures and winter accumulation these volume losses correspond to geodetic balances of 0 58 0 03 and 0 41 0 03 m w e a 1 respectively our analysis revealed high spatial complexity in patterns of elevation change varying between glaciers between measurement intervals and within and between elevation bins balances from extrapolated centre line geodetic data were the same within errors as those from full coverage dem differencing in the majority of comparisons yet significantly underestimated balance in three instances additionally field mass balance from centre line ablation stake data underestimated balances from full coverage geodetic measurements during three of six measurement periods these findings may support the hypothesis that field measurements under estimate svalbard glacier mass loss at least partly as a result of the failure of centre line measurements to account for glacier wide variations in ablation our results demonstrate the importance of deriving accurate interpolation functions and constraining extrapolation errors from sparse measurements

late holocene episodic river aggradation along the lao nong river southwestern taiwan an application to the tseng wen reservoir transbasin diversion project abstract the tseng wen reservoir transbasin diversion project the tseng wen project currently the largest water resources scheme in taiwan aims at constructing a tunnel system across the mountains to divert the water of the lao nong river to the tseng wen reservoir the largest reservoir in the island this project was suspended however because the constructed tunnel entrance on the side of the lao nong river has been buried by the 20 30 m aggradation of the river during 2009 typhoon morakot which triggered extensive landslides debris flows and killed 400 people in southwestern taiwan to understand the river history and help assess the risk to the project the fluvial debris flow sequences exposed along the 5 km long river reach upstream of the buried tunnel entrance were examined and a total of 38 radiocarbon dates were obtained for chronological constraints the study is limited by the intrinsic uncertainties of the dates and by the likelihood that much of the stratigraphic evidence has been eroded away or remains unexposed even so this study identified 9 pre historical aggradation events in the past 2 ka each of which had a magnitude comparable to or greater than the 2009 event the most recent event occurred

inverse solution of surface mass balance of midtre lovenbreen svalbard we investigate the temporal evolution and spatial distribution of mass balance on the glacier midtre lovenbreen svalbard running a diagnostic high resolution full stress ice flow model with geometries obtained from five digital elevation models dems in the period 1962 2005 we compute velocity fields and linearly interpolated volume change of the glacier we evaluate the kinematic free surface equation using these model outputs to solve the surface mass balance smb monitoring data on midtre lovenbreen allows model results to be compared with point measurements from the glacier over several decades this method allows us to estimate the mass balance over the entire glacier surface beyond the spatially limited field measurements and to derive past smb over an extended time period

quantifying the effects of climate and surface change on glacier mass balance when a mass balance is computed using an outdated map that computation does not reveal the actual mass change but older maps often must be used for practical reasons we present a method by which with a few additional measurements each year a mass balance computed with an outdated map can be transformed into an actual mass change this is done by taking into account the influence of changes in areal extent and changes in the surface elevation of the glacier since the map was made this method is applied to south cascade glacier washington u s a as an example the computed cumulative mass balance from 1970 to 1997 would have been 16 too negative if the 1970 map had not been updated while the actual volume change of a glacier is relevant to hydrological studies the change that would have occurred on a constant or static surface is more relevant to certain glacier dynamics problems and most climate problems we term this the reference surface balance and propose that such a balance which deliberately omits the influence of changes in area and surface elevation is better correlated to climatic variations than the conventional one which incorporates those influences

forecasting hazard scenarios and implications for the evaluation of countermeasure efficiency for large debris avalanches abstract the key objective of a slope failure study is to reduce deaths injuries and property damage predictions of slope failures are mandatory to reduce hazard and vulnerability of elements at risk with appropriate warning policy and properly designed countermeasures numerical modelling has been recently used as an approach to back analyse real events but few attempts have been carried out to forecast potential failure scenarios recently a debris avalanche involving about 1 2 million m 3 of debris and a nearby debris slide flow with failure volume of 0 1 million m 3 occurred in the italian prealps from the accumulation of a paleo landslide field surveys and monitoring revealed that the upper part of the slope above the largest recent landslide is unstable with a possible failure volume between 1 and 1 5 million m 3 we conducted comprehensive fieldwork and analyses including geological and geomorphological surveys compilation of a landslide inventory map collection of rainfall records study of triggering mechanisms and geotechnical properties of the failed materials slope stability analyses and back analyses of the runout phase of the landslide events through a series of slope stability analyses the possible failure volume sliding surface and topography are estimated consistent with field monitoring data furthermore with the help of calibration through back analyses of the past landslide events we assign a given degree of danger to slope elements with analogous conditions we then numerically predict the runout patterns and mobility of the potential instabilities the effectiveness of the planned passive countermeasures for potential zoning management is evaluated

svalbard glacier elevation changes and contribution to sea level rise 1 we compare satellite altimetry from the ice cloud and land elevation satellite icesat 2003 2007 to older topographic maps and digital elevation models 1965 1990 to calculate long term elevation changes of glaciers on the svalbard archipelago results indicate significant thinning at most glacier fronts with either slight thinning or thickening in the accumulation areas except for glaciers that surged which show thickening in the ablation area and thinning in the accumulation areas the most negative geodetic balances occur in the south and on glaciers that have surged while the least negative balances occur in the northeast and on glaciers in the quiescent phase of a surge cycle geodetic balances are related to latitude and to the dynamical behavior of the glacier the average volume change rate over the past 40 years for svalbard excluding austfonna and kvitoya is estimated to be 9 71 0 55 km3 yr 1 or 0 36 0 02 m yr 1 w equivalent for an annual contribution to global sea level rise of 0 026 mm yr 1 sea level equivalent

forecasting landslide hazard by the 3d discrete element method a case study of the unstable slope in the lushan hot spring district central taiwan abstract catastrophic landslides and related phenomena are commonly facilitated by the subtropical climate with frequent typhoons and recurrent earthquakes in taiwan s mountainous areas one area susceptible to potentially catastrophic landslides is located at lushan in central taiwan which is famous for its hot springs and tourism the northern slope above the hot spring district slips gradually and frequently due to heavy rainfall for safety reasons the slip affected area has been under constant borehole monitoring by government agencies and a controversial public debate has arisen over permanent evacuation of the hot spring district in this study we attempt to simulate possible scenarios of catastrophic slope failure using slip geometries derived from the monitoring data and assess potential landslide impact areas by a discrete element method using the pfc3d code in the worst case scenario the lushan hot spring district is predicted to be destroyed by debris in 20 s besides the planned regional emergency refuge is rapidly jeopardized by flooding resulted from landslide dammed lakes this study addresses catastrophic slope failure under heavy rainfall conditions given a range of friction coefficients and varied continuity of the failure surfaces it is noted that the pfc3d code has limitations in modeling all complex mechanisms of landslide particularly in modeling loss of material shear strength due to increases in pore pressure nevertheless the numerical simulation results by the 3d discrete element method provide scenario based runout paths particle velocities and landslide affected areas which are useful information for decision support and future landslide hazard assessment

elevation changes measured on svalbard glaciers and ice caps from airborne laser data precise airborne laser surveys were conducted during spring in 1996 and 2002 on 17 ice caps and glaciers in the svalbard archipelago covering the islands of spitsbergen and nordaustlandet we present the derived elevation changes lower elevation glaciers in south spitsbergen show the largest thinning rates of 0 5 m a 1 while some of the higher more northerly ice caps appear to be close to balance the pattern of elevation change is complex however due to several factors including glacier aspect microclimatological influences and the high natural annual variability in local accumulation and ablation rates anomalous changes were observed on fridtjovbreen which started surging in 1996 at the start of the measurement period on this glacier thinning of 0 6 m a 1 w as observed in the accumulation area coincident with thickening at lower elevations asymmetric thinning was found on two ice caps on nordaustlandet with the largest values on the eastern side of vestfonna but the western slopes of vegafonna the mean elevation change for all ice masses was 0 19 m a 1 w e which is 1 6 times the net mass balance value determined for the last 30 years using mass balance sensitivity estimates for svalbard suggests that the implied increase in negative balance is linked to warmer air temperatures in the late 1990s multiple linear regression suggests that mass balance is most closely correlated with latitude rather than mean altitude or longitude

3d numerical modeling using smoothed particle hydrodynamics of flow like landslide propagation triggered by the 2008 wenchuan earthquake abstract the extremely strong wenchuan earthquake triggered thousands of landslides in sichuan province china flow like landslides such as the tangjiashan wangjiayan and donghekou landslides were among the most destructive causing many casualties and serious economic damage it is therefore important to identify the flow mechanisms and investigate the specific characteristics of these flow like landslides this paper presents a three dimensional model based on smoothed particle hydrodynamics sph to simulate rapid landslide motion across 3d terrain the navier stokes equations in a cfd framework are used as governing equations and artificial viscosity is incorporated into the pressure terms in the momentum equation to dissipate energy to avoid numerical oscillation and particle penetration thus improving the stability of the numerical results a non newtonian fluid model the bingham model has proven suitable for describing the relationship between the shear strain rate and the shear stress in highly deformed soil materials in the proposed model it is used as the constitutive model to describe the fluidization characteristics of flow like landslides combined with the mohr coulomb yield criterion the model incorporates a no slip boundary condition to consider the effect of a solid boundary on slope movement ghost particles are created and assigned an artificial velocity the viscous force caused by the solid boundary is calculated using the relative velocities between the fluid and the boundary particles open multiprocessing openmp an api for multi platform shared memory parallel programming is used to improve the efficiency of the sph code running to show the validity of the proposed approach a benchmark problem of 3d dam break was simulated the calculated distances of the surge front at different times agree well with the test results numerical modeling of the propagation of the tangjiashan wangjiayan and donghekou landslides was performed by the application of sph models to real flow like landslides the whole flow processes of these flow like landslides across the 3d terrain are represented the landslides change direction split or join in and spread or contract in their flow path in response to the local topography time history curves of the velocity and displacement were obtained to analyze the movement characteristics of the landslide mass the shapes of the deposition zones after slide occurrence were investigated comparisons of the sph simulated geometry and the surveyed landslide configurations for the tangjiashan wangjiayan and donghekou landslides were conducted and show a high degree of similarity this indicates that the proposed 3d sph model can accurately represent the evolution of the final slide shape the prediction of the fluidization characteristics of earthquake induced flow like landslides can notably reduce sudden loss of life as it provides a means for mapping hazardous areas for estimating the hazard intensity and for identification and design of appropriate protective measures

airborne surface profiling of glaciers a case study in alaska a relatively lightweight and simple airborne system for surface elevation profiling of glaciers in narrow mountain valleys has been developed and tested the aircraft position is determined by kinematic global positioning system gps methods the distance to the glacier surface is determined with a laser ranger the accuracy is about 0 3 m sufficient to permit future changes to be observed over short time intervals long term changes can be estimated by comparison of profiles with existing maps elevation profiles obtained in 1993 94 from three glaciers in central and south central alaska are compared with maps made about 1950 the resulting area averaged seasonally corrected thickness changes during the interval are gulkana glacier central alaska range 11 m worthington glacier central chugach mountains 7 m and bear lake glacier kenai mountains 12 m all three glaciers retreated during the interval of comparison the estimated uncertainty in the average thickness change is 5 m which is mainly due to errors in the existing maps constraints on the accuracy of the maps are obtained by profiling in proglacial areas

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

changes in glacier volume on mt gongga southeastern tibetan plateau based on the analysis of multi temporal dems from 1966 to 2015 the accelerated retreat of glaciers and the reduction of glacier ice reserves caused by climate change can significantly affect regional water resources and hydrological cycles changes in glacier thickness are among the key indicators that reflect this process we analyzed changes observed in the elevation of glacier surfaces in the gongga mountains ggm using multi temporal digital elevation models dems derived from topographic maps srtm icesat and zy 3 data the results showed that the mean rate of change in glacier surface altitude in the ggm was 26 7 2 03 m 0 54 0 04 m a 1 between 1966 and 2015 the mean melt rates differed over different time periods latterly showing an accelerating trend as a general rule glaciers appear to be losing more volume at lower than at higher elevations further analysis of these results suggests that supraglacial debris coverage in the ggm promotes higher rates of mass loss

the thermal regime of sub polar glaciers mapped by multi frequency radio echo sounding radio echo soundings provide an effective tool for mapping the thermal regimes of polythermal glaciers on a regional scale radar signals of 320 370 mhz penetrate ice at sub freezing temperatures but are reflected from the top of layers of ice which are at the melting point and contain water radar signals of 5 20 mhz on the other hand see through both the cold and the temperate ice down to the glacier bed radio echo soundings at these frequencies have been used to investigate the thermal regimes of four polythermal glaciers in svalbard kongsvegen uversbreen midre lovenbreen and austre broggerbreen in the ablation area of kongsvegen a cold surface layer 50 160m thick was underlain by a warm basal layer which is advected from the temperate accumulation area the surface ablation of this cold layer may be compensated by freezing at its lower cold temperate interface this requires that the free water content in the ice at the freezing interface is about 1 of the volume the cold surface layer is thicker beneath medial moraines and where cold based hanging glaciers enter the main ice stream on uversbreen the thermal regime was similar to that of kongsvegen a temperate hole was found in the otherwise cold surface layer of the ablation area in a surface depression between kongsvegen and uversbreen where meltwater accumulates during the summer near the subglacial lake setevatnet 250 m a s l lovenbreen was frozen to the bed at the snout and along all the mountain slopes but beneath the central part of the glacier a warm basal layer up to 50m thick was fed by temperate ice from two cirques on austre broggerbreen a temperate basal layer was not detected by radio echo soundings but the basal ice was observed to be at the melting point in two boreholes

recent high arctic glacial sediment redistribution a process perspective using airborne lidar abstract progressive glacier thinning retreat and mass loss in the high arctic is increasingly exposing forefield sediments to processes of mobilisation and redistribution in this paper we quantify forefield sediment redistribution at midtre lovenbreen svalbard using repeat light detection and ranging lidar surveys conducted in 2003 and 2005 in combination with field based observations average surface lowering of the forefield over the observation period identified from lidar surveys is 0 05 ma 1 and two primary areas of sediment reworking are identified active fluvial incision of proglacial streams by 2 m and lateral moraine downwasting of similar magnitude multivariate analysis of fluvial and climatological field data indicates that observed forefield sediment mobilisation is driven primarily by discharge forcing but with contributions from thermoerosive processes and stochastic autogenic sediment supply during the period of observation disparity between sediment loss in forefield fluvial systems as calculated from lidar data 3000 4000 103 kg and monitoring of fluvial sediment load 1600 3500 103 kg suggests the likely presence of significant quantities of buried ice beneath a thick debris mantle as evidenced by field observations relatively uniform lowering of the moraine crest identified from our repeat lidar surveys indicates thermoerosion of an ice core however simple debris layer thickness modelling indicates an increase in variation of debris layer thickness at lower elevations providing support for the assertion that moraine disintegration is driven by complex combinations of both thermal and mechanical processes this study demonstrates the viability of using lidar in conjunction with field monitoring to better understand sedimentary deglaciation dynamics and processes and also highlights the significance of forefield areas in controlling the sediment yield from deglaciating catchments

a kinematic model of the hsiaolin landslide calibrated to the morphology of the landslide deposit abstract this paper presents results of a case study on the hsiaolin catastrophic landslide including its kinematic process and the geometry of deposition based on geomorphologic analysis the landslide initiated in thick multi aged colluvium soils at the headwaters of a small stream upslope of hsiaolin village a 3d discrete element program pfc3d was used to model the kinematic process that led to the landslide and destruction of hsiaolin village the landslide advanced from debris slide to debris avalanche during the kinematic process assuming a friction coefficient of each particle of 0 1 the predicted maximum velocity was about 70 m s a velocity which permits the debris to cross qishanxi stream and deposit on the opposite bank based on simulation results hsiaolin village was inundated in 60 to 65 s after failure initiation and at 112 s after the event the debris avalanche came to rest forming a landslide dam

deep seated rockslide avalanches preceded by mass rock creep of sedimentary rocks in the akaishi mountains central japan abstract seven large rockslide avalanches of sedimentary rocks are known in japan almost all of these major landslides were preceded by gravitational deformation of rocks mass rock creep mrc as inferred from geologic and geomorphic investigations of five rockslide avalanches in the akaishi mountains the mrc that preceded the rockslide avalanches in the akaishi mountains was characterized by a slow but steady downslope bowing of steeply dipping foliations which accompanied intensive deformation and fragmentation of the rock mass by shearing along foliations this deformation and fragmentation of the rock mass provides a basic cause for the occurrence of rockslide avalanches which occur when a creeping rock mass has lost its support from the lower part of a slope by stream erosion this type of mrc continues for a long time after a part of the creeping area has slid and results in longterm generation of debris by the landslide sear of the rockslide avalanche

stress magnitudes in the basel enhanced geothermal system abstract this paper presents the results of an evaluation of stress magnitudes in the granitic egs reservoir in basel switzerland the profile of minimum principal horizontal stress shmin is constrained by hydraulic tests but the magnitude of the maximum horizontal principal stress shmax is uncertain here we derive estimates for shmax by analysing breakout width data from an acoustic televiewer logs run in the granitic basement section of the bs 1 borehole some 81 of the borehole in the granite is affected by breakouts the approach employed to derive shmax magnitude from the estimated breakout widths is taking into account all stress components at the borehole wall including the remnant thermal stress arising from the cooling of the borehole wall by the drilling in bs 1 breakouts width tends to decrease with depth assuming there is no significant systematic change in the strength characteristics of the rock along the length of the hole for which there is no evidence the large scale trend has the consequence of implying a small gradient of the shmax profile a low shmin gradient was also implied by a stress analysis that additionally considered the occasionally coincident presence of drilling induced tension fractures the absolute values of shmax depend upon the failure criterion used criteria that consider the strengthening effect of the intermediate stress mogi coulomb and hoek brown 3d yield profiles that violate frictional limits on the strength of the crust above 4 km whereas the profiles of the mohr coulomb and rankine criteria do not the mohr coulomb criteria profiles indicate a trend in shmax from favoring strike slip faulting above 4200 m to strike slip normal faulting below this is consistent with focal mechanisms recorded during the reservoir stimulation which show a mix of strike slip and normal faulting throughout the depth range considered

using structure from motion to create glacier dems and orthoimagery from historical terrestrial and oblique aerial imagery increased resolution and availability of remote sensing products and advancements in small scale aerial drone systems allows observations of glacial changes at unprecedented levels of detail software developments such as structure from motion sfm now allow users an easy and efficient method to generate three dimensional 3d models and orthoimages from aerial or terrestrial datasets while these advancements show promise for current and future glacier monitoring many regions still suffer a lack of observations from earlier time periods we report on the use of sfm to extract spatial information from various historic imagery sources we focus on three geographic regions the european alps high arctic norway and the nepal himalayas we used terrestrial field photographs from 1896 high oblique aerial photographs from 1936 and aerial handheld photographs from 1978 to generate digital elevation models dems and orthophotos of the rhone glacier broggerhalvoya and the lower khumbu glacier respectively our analysis shows that applying sfm to historic imagery can generate high quality models using only ground control points limited camera orientation information was largely reproduced using self calibrated model data using these data we calculated mean ground sampling distances across each site which demonstrates the high potential resolution of resulting models vertical errors for our models are 5 4 m 5 2 m and 3 3 m differencing shows similar patterns of thinning at lower rhone european alps and broggerhalvoya norway glaciers which have mean thinning rates of 0 31 m a 1 1896 2010 to 0 86 m a 1 1936 2010 respectively on these clean ice glaciers thinning is highest in the terminus region and decreasing up glacier in contrast to these glaciers uneven topography exposed ice cliffs and debris cover on the khumbu glacier create a highly variable spatial distribution of thinning the mean thinning rate for the khumbu study area was found to be 0 54 0 9 m a 1 1978 2015

development of characteristic volcanic debris avalanche deposit structures new insight from distinct element simulations large scale catastrophic collapse of volcanic edifices is a relatively common phenomenon in the geologic record however the processes that occur during debris avalanche emplacement remain poorly understood and must generally be inferred from analysis of avalanche deposits in the field which are recognized to contain a suite of recurrent features such as conical surface hummocks and toreva block ridges this study uses the distinct element numerical modelling method to investigate debris avalanche emplacement processes because it allows brittle deformation of the failure mass to be examined after describing the material calibration and model setup necessary for modelling the geomechanical behaviour of a failed edifice flank a sequence of emplacement snapshots is described the simulated debris avalanche is seen to evolve from initial block sliding through extension with horst and graben structures defined by propagation and offset of large scale discontinuities to a final stage in which the avalanche flows down valley the numerical model is consistent with emplacement theory in the literature and allows for a more precise view of the processes at work during failure and the deposits created thereby for example toreva blocks are formed in the medial and proximal sections of the failure through top down propagation of normally offset discontinuities developed from upper surface tension a mechanism for surface hummock formation is also recognized involving the retention of surface blocks as these and other characteristic deposit features are formed from a flank with homogeneous material properties brittle deformation of the initially listric shaped failure mass and associated macroscopic structural evolution are recognized as important factors in failure evolution and subsequent deposit morphology

the evolution of the samaoding paleolandslide river blocking event at the upstream reaches of the jinsha river tibetan plateau abstract a large number of landslides have occurred in the upstream reaches of the jinsha river tibetan plateau due to the intensity of tectonic movement in the area remote sensing and field investigation indicate that one of them the samaoding paleolandslide previously blocked the river various river blocking phenomena are well preserved including the old landslide dam and deposits fluvial sediments and hydrostatic sandy sediment to better understand the evolution of the samaoding landslide the authors carried out thermoluminescence tl dating and numerical simulations the tl analysis shows that the landslide occurred at 10 6 0 5 ka bp discrete element method dem simulation of the landslide based on landform restoration provided results that are consistent with field observations the simulation indicates that the entire landslide process lasted for 80 s and the sliding mass reached a maximum velocity of 64 m s the landslide formed a landslide dam with a length of 1900 m a width of 600 m and a depth of 200 m the simulation results show that the level of the riverbed at that the time of the landslide was at least 25 m higher than it is today on the combined basis of the simulation results and field observations the authors propose explanation that the following valley evolution sequence occurred after river blocking the landslide dam experienced flood overtopping and then was eroded until it had mostly had been transported away by river flow and the river then rapidly incised the bedrock to form the present day landform based on the field investigations the authors summarize the failure mechanism of steep inclined antidip rockslides and found that tectonics play an important role in the formation of landslide dams or trigger of landslides and the failure of landslide dams in an active tectonic environment of tibetan plateau

the structural geometric and volumetric changes of a polythermal arctic glacier during a surge cycle comfortlessbreen svalbard various parameters of the most recent surge of the polythermal glacier comfortlessbreen in northwest svalbard have been assessed through a combination of remote sensing and ground observations analysis of a digital elevation model time series shows a marked change in the geometry of the glacier from quiescence 1990 and earlier into the late surge phase 2009 the transfer of 0 74 km3 of ice caused up to 80 m of surface drawdown in the reservoir area above the equilibrium line whilst ice built up in a spatially concentrated manner in the receiving zone below the equilibrium line a ramp of ice c 100 m above quiescent level developed in the lower reaches of the glacier late in the surge also in the lower reaches of the glacier structures attributable to the passage of a kinematic wave are identified and the migration of a surge front on the glacier is thus inferred in a conceptual model we consider that a bend in the valley in which the glacier resides and convergence with tributary glaciers to be significant factors in the style of surge evolution their flow restrictive interference results in slow initial mass transfer and the growth of a surge front within 3 4 km of the terminus copyright 2015 john wiley sons ltd

elevation volume and terminus changes of nine glaciers in north america nine glaciers in alaska and washington u s a originally mapped as part of the international geophysical year igy in 1957 58 were re mapped between 1993 and 1996 eight using airborne surface elevation profiling and the ninth using ground based kinematic global positioning system methods elevation volume and terminus changes were determined for the approximately 38 year period between the igy mapping and the profiling all nine glaciers showed substantial thinning at lower elevations seven of the nine thickened at higher elevations none of the glaciers had a significant net volume increase two had close to zero change and the others had a decrease for the eight glaciers for which we could obtain quantitative information the mean thickness change was 10 m with a large scatter 8 m standard deviation the volume and terminus changes had no clear geographic pattern and no simple relationship between volume change and terminus advance or retreat was identified the largest error in the estimated volume changes is due to map errors

recent rapid thinning of the mer de glace glacier derived from satellite optical images the rapid wastage of mountain glaciers and their contribution to sea level rise require worldwide monitoring of their mass balance in this paper we show that changes in glacier thickness can be accurately measured from satellite images we use spot image pairs to build digital elevation models dems of the mont blanc area french alps for different years to register the dems we adjust their longitude latitude and altitude over motionless areas the uncertainty of the thickness change measurement is greatly reduced by averaging over areas covering altitude intervals of 50 m comparisons with topographic profiles and a differential dem from aerial photographs obtained on the mer de glace indicate an overall accuracy of 1 m for the thickness change measurement below 2100 m satellite dems show an evolution of the thinning rate from 1 0 4 m a years 1979 1994 to 4 1 1 7 m a 2000 2003

the tsaoling landslide triggered by the chi chi earthquake taiwan insights from a discrete element simulation article i nfo in the village of tsaoling in yunlin county taiwan a major landslide was triggered by the chi chi earthquake in 1999 with more than 125 10 6 m 3 of rock displaced the kinematic behaviour of this landslide is simulated using a 2d discrete element model pfc2d code our numerical model is composed of discs bonded together the initial boundary conditions are applied along the ball wall contacts by using derived velocities integrated from the strong motion data with a duration of 160 s including the peak acceleration near tsaoling the constraints are mainly issued from the final geometry of the landslide including its capacity to cross the river valley and reach a significant elevation on the opposite mountain flank they also result from a variety of geological and hydrological observations including the local levels of material disruption and the location of survivors our modelling thus indicates that a low friction coefficient about 0 15 and a medium strength are required to account for the actual landslide characteristics a self lubrication mechanism probably accounts for the low residual friction our model also suggests that the maximum velocity of sliding reached 50 m s a result that cannot be checked in the absence of actual measurements in addition to friction the strength of sliding block is of special importance because it controlled the possibility for the upper layer fragments to roll and get buried and hence the probability of survival

stagnation and mass loss on a himalayan debris covered glacier processes patterns and rates the ablation areas of debris covered glaciers typically consist of a complex mosaic of surface features with contrasting processes and rates of mass loss this greatly complicates glacier response to climate change and increases the uncertainty of predictive models in this paper we present a series of high resolution dems and repeat lake bathymetric surveys on ngozumpa glacier nepal to study processes and patterns of mass loss on a himalayan debris covered glacier in unprecedented detail most mass loss occurs by melt below supraglacial debris and melt and calving of ice cliffs backwasting although ice cliffs cover only 5 of the area of the lower tongue they account for 40 of the ablation the surface debris layer is subject to frequent re distribution by slope processes resulting in large spatial and temporal differences in debris layer thickness enhancing or inhibiting local ablation rates and encouraging continuous topographic inversion a moraine dammed lake on the lower glacier tongue spillway lake underwent a period of rapid expansion from 2001 to 2009 but later experienced a reduction of area and volume as a result of lake level lowering and sediment redistribution rapid lake growth will likely resume in the near future and may eventually become up to 7 km long

supraglacial weathering crust dynamics inferred from cryoconite hole hydrology water levels in cryoconite holes were monitored at high resolution over a 3 week period on austre broggerbreen svalbard these data were combined with melt and energy balance modelling providing insights into the evolution of the glacier s near surface hydrology and confirming that the hydrology of the near surface porous ice known as the weathering crust is dynamic and analogous to a shallow perched aquifer a positive correlation between radiative forcing of melt and drainage efficiency was found within the weathering crust this likely resulted from diurnal contraction and dilation of interstitial pore spaces driven by variations in radiative and turbulent fluxes in the surface energy balance occasionally causing sudden drainage events a linear decrease in water levels in cryoconite holes was also observed and attributed to cumulative increases in near surface ice porosity over the measurement period the transport of particulate matter and microbes between cryoconite holes through the porous weathering crust is shown to be dependent upon weathering crust hydraulics and particle size cryoconite holes therefore yield an indication of the hydrological dynamics of the weathering crust and provide long term storage loci for cryoconite at the glacier surface this study highlights the importance of the weathering crust as a crucial component of the hydrology ecology and biogeochemistry of the glacier ecosystem and glacierized regions and demonstrates the utility of cryoconite holes as natural piezometers on glacier surfaces

updated estimates of glacier volume changes in the western chugach mountains alaska and a comparison of regional extrapolation methods and 2001 2004 average net balance rates ranged between 3 1 to 0 16 m yr 1 for the tidewater and 1 5 to 0 02 m yr 1 for the nontidewater glaciers we tested several methods for extrapolating these measurements to all the glaciers of the western chugach mountains using a process similar to cross validation predictions of individual glacier changes appear to be difficult probably because of the effects of glacier dynamics which on long multidecadal timescales complicates the response of glaciers to climate in contrast estimates of regional contributions to rising sea level were similar for different methods mainly because the large glaciers whose changes dominated the regional total were among those measured for instance the above sea level net balance rate of columbia glacier 3 1 0 08 km 3 yr 1 water equivalent weq or an equivalent rise in sea level sle of 0 0090 0 0002 mm yr 1 was nearly half of the total regional net balance rate of the western chugach mountain glaciers 7 4 1 1 km 3 yr 1 weq or 0 020 0 003 mm yr 1 sle between 1950 1957 and 2001 2004 columbia glacier is a rapidly retreating tidewater glacier that has lost mass through processes largely independent of climate tidewater glaciers should therefore be treated separately when performing regional extrapolations

rainfall induced landslides and debris flows in this preface we introduce the special issue on rainfall induced landslides and debris flows the topic is of high interest for many practical and scientific reasons in fact rainfall is the most relevant factor for the triggering of both shallow and deep seated landslides and rainfall analysis is the most frequently adopted approach for forecasting the occurrence of such phenomena the six papers of the special issue cover most of the key issues relative to rainfall induced landslides starting from the analysis of these contributions we identify and discuss in this paper several main topics that deserve further research in the field of rainfall induced landslide such as the uncertainty of the data the quality of geotechnical analysis the validation of the models and the applicability of results in the framework of natural hazards copyright 2007 john wiley sons ltd

particulate kinematic simulations of debris avalanches interpretation of deposits and landslide seismic signals of mount saint helens 1980 may 18 summary we construct a new class of granular landslide models in which avalanches are simulated with large numbers of independent particles moving under the influence of topographically derived gravitational and centripetal acceleration concurrently the particles suffer deceleration due to basal and dynamic friction the novel aspect of the calculation is that complex particle toparticle interactions fluctuating basal contacts and unresolved topographic roughness within and below the deforming flow are mimicked by random perturbations in along track and cross slope acceleration we apply the method to the 1980 may 18 mount saint helens debris avalanche by constraining the initial geometry and structure of the slide mass from geological data and the initial failure sequence from eyewitness accounts after tuning coefficients of mechanical friction and random accelerations the landslide simulation generates a final deposit whose extent thickness morphological structure and lithological variation closely replicate those observed moreover the model avalanche is consistent kinematically with mapped patterns of bedrock scouring deposit superelevation and net force history implied from seismic records to be successful the slide mass must be divided into upper high friction and lower low friction members this division corresponds to fresh water unsaturated and hydrothermally altered water saturated rock units and points to a mechanical explanation of the kinematics of the debris avalanche success in reproducing many features of the mount saint helens avalanche indicates that debris deposit data may be used to determine the kinematic histories of less well observed landslides

acceleration in thinning rate on western svalbard glaciers 1 geodetic measurements indicate that a number of glaciers in western svalbard ranging in size from 5 1000 km2 are losing mass at an accelerating rate the average thinning rate for midtre lovenbreen the glacier with the best data coverage has increased steadily since 1936 thinning rates for 2003 2005 are more than 4 times the average for the first measurement period 1936 1962 and are significantly greater than presented previously on slakbreen thinning rates for the latest measurement period 1990 2003 are more than 4 times that of the period 1961 1977 thinning of several glaciers along a previously measured airborne lidar profile in wedel jarls land has also increased doubling between the period 1990 1996 and 1996 2002 our results imply an increased sea level contribution from svalbard in addition the mass loss is an important influence on measured rates of rebound on western svalbard and should be factored into analysis of grace results

rapid wastage of alaska glaciers and their contribution to rising sea level we have used airborne laser altimetry to estimate volume changes of 67 glaciers in alaska from the mid 1950s to the mid 1990s the average rate of thickness change of these glaciers was 0 52 m year extrapolation to all glaciers in alaska yields an estimated total annual volume change of 52 15 km 3 year water equivalent equivalent to a rise in sea level sle of 0 14 0 04 mm year repeat measurements of 28 glaciers from the mid 1990s to 2000 2001 suggest an increased average rate of thinning 1 8 m year this leads to an extrapolated annual volume loss from alaska glaciers equal to 96 35 km 3 year or 0 27 0 10 mm year sle during the past decade these recent losses are nearly double the estimated annual loss from the entire greenland ice sheet during the same time period and are much higher than previously published loss estimates for alaska glaciers they form the largest glaciological contribution to rising sea level yet measured

elevation change mass balance dynamics and surging of langjokull iceland from 1997 to 2007 in situ mass balance survey is a joint effort of the glaciology group institute of earth sciences university of iceland and the national power company landsvirkjun we thank philippe crochet and tomas johannesson from the icelandic meteorological office for providing the gridded climate data and for useful discussions about the climatology of langjokull the 2007 lidar data were collected by the uk natural environment research council airborne research and survey facility grant ipy 07 08 additional funding was provided by the united states national science foundation grant no dge 1038596 st catharine s st john s and trinity colleges and the university of cambridge b b roberts and scandinavian studies funds we thank cameron rye for initial help coding the mass balance model

september 2005 rain induced catastrophic rockslides on slopes affected by deep seated gravitational deformations kyushu southern japan river rejuvenation forms convex slope breaks that can destabilize nearby slopes leading to gravitational deformation and in some cases catastrophic sliding of the slopes during heavy rainstorms such landslides were induced by typhoon 0514 which passed to the west of kyushu island japan on 6 september 2005 five large catastrophic rockslides occurred aligning along convex slope breaks 150 to 300 m above the present river bed of the mimi river the slope breaks are inferred to have been formed by rejuvenation of the river geological and geomorphological investigation revealed that these slides occurred in sandstone and mudstone of the cretaceous shimanto group and were preceded by slope deformation which generated gravitational folds and faults that appeared as scarplets at the tops of the deformed areas the slopes seem to have been in critical condition just before catastrophic failure which was triggered by the rainstorm

evolution of the large landslide induced by typhoon morakot a case study in the butangbunasi river southern taiwan using the discrete element method abstract in 2009 typhoon morakot delivered high intensity rainfall and triggered many sites of large landslide which projected areas were larger than 10 000 m 2 from the satellite image especially in southern taiwan according to dtm analysis the material volume of the large landslide in butangbunasi river was more than four times larger than that of the nearly famous landslide disaster in hsiaolin village nevertheless the different movement of these two large landslides led to different disaster impacts based on literatures and field works the large hsiaolin landslide was a catastrophic landslide which had high velocity and less energy loss in the kinematic process the source area of the large landslide in the butangbunasi river on the other hand was composed of several landslide events and the kinetic energy dissipated when the landslide materials attained to riverbed in sequence in this study we divided the butangbunasi river large landslide into five slope units namely a b c d and e landslide events to recognize the mechanism of the large landslide and the simulation by using the particle flow code 3d pfc3d which is based on the discrete element method provided the kinematic process of the large landslide in the butangbunasi river it is noticed that most of the initial energy dissipated during the movement which the fist happening landslide event counteracted the crash of the follow up events and the residual energy gradually declined by the collision interaction of landslide blocks until the end of the large landslide the result helps to reconstruct the evolution of the large landslide from small scale landslide events and contributes to predict the affected region of the disaster it also reveals that even though the impact of the large landslide is reduced by sequent small scale landslide events there still remain secondary disasters such as landslide dam which show a high potential risk in the river valley and midstream

stress orientations from borehole wall fractures with examples from colorado east texas and northern canada azimuthally aligned breakouts in oil wells are explained as shear fractures in the zone of amplified stress difference near the borehole in a stress field having unequal horizontal principal stres

borehole instabilities in the ktb main borehole borehole instability has been a central problem for drilling operations and borehole measurements within the german continental deep drilling project ktb main borehole which has been drilled entirely through crystalline rocks mostly paragneisses and metabasites the types of borehole instabilities observed were drilling induced tensile fractures breakouts and convergence zones these were strongly dominated by foliate graphitic gneisses with sometimes very low and anisotropic rock strength unfavorably high and nonuniform horizontal stresses and the effects of hydraulic interactions of the drill mud and formation fluids the instability problems encountered in the ktb main borehole have clearly demonstrated that undergauge sections which first appeared at depths below 7500 m and probably resulted from time dependent convergence of wet crystalline rocks had a much greater impact on the drilling operations than all the breakouts or drilling induced tensile fractures

mobility of long runout rock flows a discrete numerical investigation summary in the perspective of studying the mobility and deposit geometry of long runout flows discrete numerical simulations of model granular avalanches over simple topography are performed analysing the behaviour of the ratio h l depending on the parameters varied in the simulations we show its poor sensitivity to the topographic parameters namely the initial height of the flowing mass and the slope on the contrary a correlation between h l and the frictional properties of the material is established however the existence of variations of the effective friction induced by the dynamics are not reflected by the value of h l as an alternative to the h l description of the flow behaviour we propose a new scaling for the runout distance taking into account the lateral extension l0 of the relief forming the normalized runout l l0 and defining the aspect ratio a of the topography we show the dependence of l l0 on a thus generalizing previous analysis of martian data analysing the correlation between the normalized runout and the front velocity for the numerical simulations we show how l l0 depends both on the frictional properties of the material and on the dynamics of the flow this result suggests the necessity of evaluating the lateral extension of the relief l0 in the case of natural flows in order to define a horizontal travel index including the topography in an attempt to better understand the flow dynamics analysing the deposit for both simulations and real flow data we evidence a common behaviour suggesting that the geometric factors prevail in the spreading dynamics irrespective of the details of the flow context and conditions we moreover assert the relevance of discrete simulations to the discussion of real cases

evaluating failure mechanisms of dip slope using a multiscale investigation and discrete element modelling abstract this study proposed an in depth multiscale analysis procedure to identify the dip slope area and assess dip slope stability and influencing area the proposed analysis procedure comprised five stages 1 identifying the potential area of a dip slope 2 analyzing the possible failure types of the dip slope 3 evaluating slope activity 4 analyzing dip slope stability under the influence of possible triggering factors and 5 assessment of the deformation and deposition area to validate the proposed procedure the chaochouhu region of taiwan was analyzed as a dip slope case in stages 1 to 3 the scale of the utilized map and the precision of associated data were evaluated to identify the potential area of a dip slope the possible failure types and the activity of each slope unit in stages 4 and 5 the processes of deformation and sliding in a high activity slope unit were simulated using the discrete element method the numerical model was first verified using in situ monitoring data obtained from inclinometers subsequently the model was used to predict the slope behavior under conditions of wetting deterioration of geomaterial the multiscale analysis revealed comprehensive information regarding the dip slope the application of the proposed approach would be useful to civil engineers for evaluating dip slope stability as well as to relevant authorities for planning hazard mitigation strategies

changes in the glacier extent and surface elevation in xiongcaigangri region southern karakoram mountains china the recent evolution of the karakoram glaciers widely acknowledged as peculiar remains poorly understood the xiongcaigangri region is in the south of karakoram and its glacial melt water has a significant impact on the local water supply and ecosystem in this work glacial changes in the xiongcaigangri region were detected based on topographic maps and landsat mss tm etm oli srtm4 1 dem and glas icesat remote sensing data and gis techniques the results show that from 1968 to 2013 the total glacier area decreased from 181 10 km 2 to 178 47 km 2 an overall loss of 2 63 km 2 or 1 45 of the entire 1968 glacial area the inverse relationship between the retreating area and the change rate indicates that small glaciers may be retreating faster the main glacial melting occurred below 6500 m a s l and the reduction of 2 62 km 2 accounts for 99 62 of the total glacial retreat in the area studied the very slight reduction of 0 01 km 2 over 6500 m a s l accounts for only for 0 38 of the total glacial retreat in the area studied the results also show that the glacier areas are decreasing on all slopes and larger area losses have been observed on smaller slopes whereas smaller area losses have been observed on the larger slopes the different aspects of the study all showed glacier retreat taking place between the period from 1968 to 2013 the largest area decrease is in west and the area lost in the other aspect was comparatively small total glacier mass loss in the xiongcaigangri region is estimated to be 10 97 22 39 10 8 m 3 w e between 1968 and 2000 the average elevation loss estimated from the icesat and 2000 srtm difference was from 4 69 3 40 m per year and the average elevation loss between srtm and 1968dem was from 0 92 to 0 66 m per year increasing temperatures along with decreasing precipitation was determined to be the primary factor driving the glacier retreat in the xiongcaigangri region c 2014 elsevier ltd and inqua all rights reserved

glaciers dominate eustatic sea level rise in the 21st century ice loss to the sea currently accounts for virtually all of the sea level rise that is not attributable to ocean warming and about 60 of the ice loss is from glaciers and ice caps rather than from the two ice sheets the contribution of these smaller glaciers has accelerated over the past decade in part due to marked thinning and retreat of marine terminating glaciers associated with a dynamic instability that is generally not considered in mass balance and climate modeling this acceleration of glacier melt may cause 0 1 to 0 25 meter of additional sea level rise by 2100