an examination of controls on debris flow mobility evidence from coastal british columbia we characterize and consider controls to runout distance of debris slides and debris flows using 1700 field observations supplemented by air photograph interpretation from coastal british columbia we examine the role of slope on deposition and scour and determine that they occur on steeper and flatter slopes respectively than previously reported mean net deposition occurred on slopes between 18 and 24 for open slope failures and between 12 and 15 for channelized debris flows we demonstrate a practical method for estimating both entrainment and runout in the field and in a gis and provide an example entrainment map for vancouver island british columbia we consider other controls to post failure landslide mobility including the role of gullies and stream channels roads and benches and intact forests shallow landslides that hit streams and gullies at acute angles had a high probability of transforming into a channelized debris flow whereas landslides that hit streams and gullies at obtuse angles did not forests played a substantial role in landslide runout debris flows travelling through a logged slope deposited much of their load when hitting a forest boundary and stopped entirely within 50 m of that boundary in 72 of the cases examined roads also tended to stop or reduce the size of open slope debris flows in 52 of the cases the results are expected to be useful to land management applications in regions with frequent shallow landsliding

long runout rockslide on glacier at tsar mountain canadian rocky mountains potential triggers seismic and glaciological implications a rhomboidal shaped rockslide with a length of 2 2 km and an area of 1 35 km2 covers 30 of a small clemenceau icefield group cirque glacier by means of remote sensing airborne photography climate and seismic data analysis the extent timing possible trigger mechanisms and rockslide effects on the glacier are discussed an ml 2 0 seismic event on 14 september 2000 represents the rockslide and has a spindle shaped waveform and high energy in the low frequencies based on a strong signal duration of 56 108 seconds the rockslide had an average runout velocity of 22 45 m s 1 stress fatigue and a combination of rain and snow followed by rapid melt and night time freezing could have co triggered the slide additional seismic events with epicentres 40 km from the cirque were recorded 26 times since 1985 and range between ml 0 9 3 3 but none were caused by or triggered large mass movement with a rock source volume of 1 6 106 m3 and a deposited volume of 2 4 106 m3 the sum of bulking and entrainment is between 25 and 150 five melt seasons post event levees 20 30 m wide tower 30 m over the surrounding glacier rockslide characteristics and its fahrboschung of 15 height length h l 0 28 indicate that this rockslide is quite typical for long runout rockslides on glaciers however the basal friction coefficient was higher than found on other glaciers and could relate to the presence of medial moraines transverse to the flowline and to pre slide debris cover the difference between the coefficient of friction in the main flowline 0 11 0 14 and that in a lobe confined between two medial moraines 0 065 suggests that confinement increases mobility by 70 115 apart from reduced ablation under the rock debris effects of the rockslide on the glacier were minimal copyright 2010 john wiley sons ltd

dynamic analysis and field investigation of a fluidized landslide in guanling guizhou china abstract on june 28 2010 a large catastrophic landslide was triggered by a heavy rainfall in guanling guizhou china this catastrophic event destroyed two villages and caused 99 casualties the landslide involved the failure of about 985 000 m 3 of sandstone from the source area the displaced materials traveled about 1300 m with a descent of about 400 m covering an area of 129 000 m 2 with the final volume being accumulated to be 1 840 000 m 3 approximately to provide information for hazard zonation of similar type of landslides in the same area we used a dynamic model dan3d to simulate the runout behavior of the displaced landslide materials and found that a combined frictional vollemy model could provide the best performance in simulating this landslide and the runout is precisely duplicated with a dynamic friction angle of 30 and a pore pressure ratio r u of 0 55 for the materials at the source area and with vollemy parameters of friction coefficient f 0 1 dimensionless and turbulent coefficient 400 m s 2 the simulated results indicated that the duration of the movement is estimated at about 60 s for a mean velocity 23 m s to examine the effectiveness of simulation by means of dan3d and also to evaluate the reactivation potential of these displaced landslide materials depositing on the valley we used electrical resistivity tomography ert method to survey the depth and internal structure of landslide deposits the ert results showed that dan3d gave a good prediction on the shape and runout distance of the landslide deposits although the predicted maximum depths of landslide deposit on some areas were differing from those obtained by ert method

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

comparative analysis of contributing parameters for rainfall triggered landslides in the lesser himalaya of nepal in the himalaya people live in widely spread settlements and suffer more from landslides than from any other type of natural disaster the intense summer monsoons are the main factor in triggering landslides however the relations between landslides and slope hydrology have not been a focal topic in himalayan landslide research this paper deals with the contributing parameters for the rainfall triggered landslides which occurred during an extreme monsoon rainfall event on 23 july 2002 in the south western hills of kathmandu valley in the lesser himalaya nepal parameters such as bedrock geology geomorphology geotechnical properties of soil and clay mineralogy are described in this paper landslide modeling was performed in seep w and slope w to understand the relationship of pore water pressure variations in soil layers and to determine the spatial variation of landslide occurrence soil characteristics low angle of internal friction of fines in soil medium range of soil permeability presence of clay minerals in soil bedrock hydrogeology and human intervention were found to be the main contributing parameters for slope failures in the region

prediction of debris flow inundation areas using empirical mobility relationships abstract a method proposed for delineating lahar hazard zones in volcanic valleys is adapted to debris flows the original method is based on two predictive equations that relate the lahar volume to the cross sectional inundated area and to the planimetric inundated area these predictive equations were derived by combining a scaling analysis of lahar kinematics with the statistical analysis of data for 27 historical lahars this paper tests the applicability of this approach to debris flow fans forty debris flow basins in the italian alps were surveyed and data on 27 historical debris flow events were collected in the field or by means of aerial photo analysis collected data reveal that the flow area a and the planimetric area b of a debris flow are linearly correlated to the debris flow volume v on a logarithmic scale with high statistical significance moreover the computed regression equations are very similar to those obtained from other published datasets on debris flows leading to the global fitting equations a 0 08 v 2 3 and b 17 v 2 3 these predictive equations are then implemented in an automated code dflowz that delineates the inundated area on a debris flow fan on the basis of a user specified debris flow volume taking the statistical uncertainty in the prediction into account dflowz is simple reproducible and it can handle both confined and unconfined flow the model is tested against 10 historical debris flow events providing a satisfactory agreement between observed and computed inundated areas in spite of the limitations due to dem accuracy and statistical uncertainty of the regression parameters test results show that the method can be useful for practical applications

two dimensional water flood and mudflow simulation flo 2d is a two dimensional finite difference model that simulates clear water flood hazards mudflows and debris flows on alluvial fans and urban floodplains interactive flood or mudflow routing between channel street and floodplain flow is performed using a uniform grid system to describe complex floodplain topography a quadratic rheological model developed from field and laboratory mudflow data enables appropriate simulations of flooding conditions ranging from clear water to hyperconcentrated sediment flows computer aided design cad graphics of predicted time sequenced flood depths automates the delineation of flood hazards replication of the 1983 rudd creek mudflow in utah demonstrates the capability of the model

investigation and dynamic analysis of the long runout catastrophic landslide at the shenzhen landfill on december 20 2015 in guangdong china at 11 40 a m december 20 2015 a catastrophic landslide occurred in shenzhen guangdong southeast china seventy seven people were killed and 33 buildings were buried or damaged which were in the direct path of the landslide at the guangming new district the landslide involved 2 73 million m3 of the municipal solid waste msw and had a horizontal runout distance of 1100 m over a vertical distance of 113 m which was equivalent to a fahrboschung of 6 and covered an area of 0 38 km2 basic post failure characteristics are described in this study dynamic simulation software danw and rheological models were used to simulate the runout behavior of the displaced landslide material in order to provide information for the hazard zonation of similar types of potential msw landslides the simulated results revealed that a combination of the frictional model and voellmy model is able to provide the best performance in simulating this landslide also the results showed that this landslide had a duration of about 50 s with a maximum velocity of 22 4 m s it was expected that these models and parameters could improve the accuracy of future hazard assessments of areas with geological topographical and climatic features similar to the shenzhen hong ao landfill

analysis of debris flow surges using the theory of uniformly progressive flow coarse debris flows develop surges with distinct longitudinal sorting although highly unsteady such flow often appears to attain a steady state condition moving over long distances with approximately constant velocity and maximum depth typically a steep bouldery front is followed by an accumulation of liquid slurry which in turn decays into a dilute tail such sorting has long been recognized by field workers but its influence on the dynamic behaviour of debris flow surges has not yet been fully clarified by analysis a simple model is presented using the theory of uniformly progressive flow and incorporating zoned longitudinal variation in rheology it is shown that non homogeneity can cause very significant magnification of the peak discharge depending on the slope angle and on the length of the frontal boulder concentration the shape of the surge flow profiles is determined not only by the rheology of the retained material but by the longitudinal variation of material characteristics as a result excessive reliance on laboratory derived rheological constitutive relationships is not advisable models of debris flow surges should be non homogeneous and able to incorporate zones of contrasting rheology copyright 2000 john wiley sons ltd

numerical modelling of entrainment deposition in rock and debris avalanches abstract rock and debris avalanches as well as debris flows are characterized by peculiar behaviour influenced by geometry of the initial failure surface topography involved materials involved and water content during their motion rock avalanches can entrain large volumes of sediments both in a dry and in a saturated state entrained dry material has generally the consequence to reduce the total landslide runout whereas entrainment of almost saturated material can have more complex consequences we use a finite element code to simulate the motion of a moving landslide mass on materials with different properties and along very sharp topographies erosion and deposition can be modelled as well as interaction with obstacles of different characteristics we present two examples of the modelling problems and capabilities we simulated the runout of a rock avalanche on a ground formed by alluvial material under dry and saturated conditions this material can be entrained and plowed by the impacting and running rock avalanche material sensitivity of the erosion and transport mechanisms has been analysed by performing different analyses the simulated case study is the 6 10 5 m 3 arvel rock avalanche 1922 switzerland for which a reliable set of pre and post failure observations is available final geometry mass redistribution velocities and runup are used to validate the model capabilities and study the effects of different material properties

the avalanche lake rock avalanche mackenzie mountains northwest territories canada description dating and dynamics at avalanche lake located in the backbone ranges of the mackenzie mountains about 200 106 m3 of massive devonian carbonate rock slid down remarkably planar bedding surfaces dipping at 30 and c

application of the material point method to simulate the post failure runout processes of the wangjiayan landslide abstract the first part of the paper presents a brief description of the material point method mpm including the governing equations solution scheme and a benchmark problem of soil collapse simulated using the method in the second and third part of the paper the post failure runout process of the wangjiayan landslide is simulated and analyzed the landslide s final topography and information from post failure in situ survey and laboratory tests are used to constrain the accuracy of computational results the kinematic behaviors of the failure mass are investigated in terms of displacement velocity effective plastic strain fields and topography changes during the movement comparisons are made between conditions with and without buildings on the deposition area numerical computations demonstrate that the presence of buildings on the sliding path strongly governs the flow regime run out distance velocity strain field and final deposition topography of the landslide so it is very essential to incorporate the effects of buildings in the modelling and analyses numerical results considering buildings show that the slide lasts about 30 s with the most rapid phase occurring between 6 and 12 s and that the maximum simulated velocity among the sliding particles in the landslide is 43 5 m s indicates that the moving of the landslide mass was very fast the run out distance simulated with mpm matches the measured post earthquake topography well whereas the shape of the simulated deposition zone is a little differs the buildings influence the sliding by shortening the overall run out distance decelerating the movement of the bottom layer and increasing the internal deformation and mixing among deposition layers

neoproterozoic earth moon dynamics rework of the 900 ma big cottonwood canyon tidal laminae the tidal rhythmites in the proterozoic big cottonwood formation bcc of utah the neoproterozoic elatina formation of the flinders range of southern australia and the lower pennsylvanian mansfield formation of indiana indicate that the rate of retreat of the lunar orbit has been approximately constant since the late precambrian and closely matches the present epoch value determined from apollo lasers examination of a new bcc core leads to a slightly revised length of day lod and modified values for other earth moon dynamical parameters thus implying the length of day 900 million years ago reported earlier by sonett et al 1996 should be modified to 18 9 hrs

numerical analysis of dynamics of debris flow over erodible beds in wenchuan earthquake induced area the basal entrainment of debris flows play a significant role in its amplification and the final volume of deposition could be several to hundred times of its initial volume in this paper the shallow water equations coupled with basal material entrainment applied in debris flows have been given to demonstrate the amplification a new basal entrainment model taking advantage of both coulomb and voellmy frictional laws are proposed providing a unified formula to simulate the stop and go process of debris flows both time and space second order maccormack tvd finite difference method is suggested to solve the coupled equations numerical comparisons with usgs flume experiment and hongchun gully debris flow in wenchuan earthquake induced area are carried out to prove its effectiveness it is established that the momentum exchange term between the flows and the basal materials has a significant influence on the dynamic characteristics and the entrainment effects are essential to model the dynamic process of debris flows in an earthquake induced area c 2014 elsevier b v all rights reserved

long runout mechanism and landsliding behaviour of large catastrophic landslide triggered by heavy rainfall in guanling guizhou china a large catastrophic landslide was triggered by a heavy rainfall on 28 june 2010 in guanling guizhou china the landslide buried two villages and killed 99 people along the runout path the lands

entrainment of bed material by earth surface mass flows review and reformulation of depth integrated theory earth surface mass flows such as debris flows rock avalanches and dam break floods can grow greatly in size and destructive potential by entraining bed material they encounter increasing use of depth integrated mass and momentum conservation equations to model these erosive flows motivates a review of the underlying theory our review indicates that many existing models apply depth integrated conservation principles incorrectly leading to spurious inferences about the role of mass and momentum exchanges at flow bed boundaries model discrepancies can be rectified by analyzing conservation of mass and momentum in a two layer system consisting of amoving upper layer and static lower layer our analysis shows that erosion or deposition rates at the interface between layers must in general satisfy three jump conditions these conditions impose constraints on valid erosion formulas and they help determine the correct forms of depth integrated conservation equations two of the three jump conditions are closely analogous to rankine hugoniot conditions that describe the behavior of shocks in compressible gasses and the third jump condition describes shear traction discontinuities that necessarily exist across eroding boundaries grain fluid mixtures commonly behave as compressible materials as they undergo entrainment because changes in bulk density occur as the mixtures mobilize and merge with an overriding flow if no bulk density change occurs then only the shear traction jump condition applies even for this special case however accurate formulation of depth integrated momentum equations requires a clear distinction between boundary shear tractions that exist in the presence or absence of bed erosion

influence of the scar geometry on landslide dynamics and deposits application to martian landslides received 24 january 2011 revised 23 june 2011 accepted 30 june 2011 published 4 october 2011 1 landslides dynamics prediction remains difficult in spite of a considerable number of studies the runout distance is widely used in analysis of landslide dynamics and in the calibration of the rheological parameters involved in numerical modeling however the unknown impact of the significant uncertainty in the shape of the initial released mass on the runoutdistanceandontheoverallshapeofthedepositraisesquestionsabouttherelevanceof these approaches the impact of the initial scar geometry on flow and distribution of the deposits is studied here using satellite data and numerical modeling of theoretical landslides and martian landslides informed by geomorphological analysis by varying the initial scar geometry from spoon shaped to steep wall geometry our results show that the runout distance is a very robust parameter that is only slightly affected by the change in the geometry of the initial scar on the contrary the lateral extent of the deposit is shown to be controlled by the scar geometry providing unique insights into the initial landsliding conditionsonmarsandmakesitpossibletoaccuratelyrecoverthevolumeinitiallyinvolved an essential ingredient for volume balance calculation a feedback analysis of valles marineris landslides can be drawn showing good agreement between numerical results and geomorphological analysis the geometry of the initial scar inferred from numerical modeling is strongly correlated with the regional tectonic history in valles marineris area

continuum simulation of flow failures dynamic aspects of several catastrophic slope failures have been evaluated by unsteady flow modelling assuming two dimensional or quasi three dimensional transient flow of an incompressible bivi

influence of flow resistance stresses on debris flow runout the hydrodynamic modeling of debris flows is challenged by the complicated mechanism of debris flow and the large variability of material composition therefore in the dynamic continuum modeling of debris flows it is essential to select suitable rheological and associated friction parameters the quadratic rheological model is the most comprehensive approach because it considers the effects of viscous behavior solid particle resistance turbulent properties and friction characteristics of debris flow therefore this study adopted the quadratic model as the governing flow resistance stress and analyzed the influence of various flow resistance stresses to evaluate the runout performance the shallow water equations with modified bottom friction were discretized and the developed model was validated against a dam break flow and a spreading of circular cone problem then to investigate the relationship between the flow resistance relations and the bottom shear stresses exerted by the cones and dry bed the model was applied to runout in a rectangular domain with three cone shaped obstacles an actual field runout event that occurred in korea in 2011 was replicated and the runout paths and flow patterns were analyzed according to the various resistance stresses by considering both the extremely rapid runout velocity and the striking run up height the results obtained by the quadratic stress relation achieved the best performance however for the successful application of the quadratic approach three parameters had to be adjusted with consideration to locality

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

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

rays and secondary craters of tycho abstract the large fresh crater tycho in the nearside lunar highlands has an extensive system of bright rays covering approximately 560 000 km 2 containing dense clusters of secondary craters examination of crater densities in several clusters shows that tycho produced almost 10 6 secondary craters larger than 63 m diameter this is a lower limit because small crater densities are reduced most likely by mass wasting we estimate a crater erasure rate of 2 6 cm myr varying with crater size and consistent with previous results this process has removed many small craters and it is probable that the original number of secondary craters formed by tycho was higher also we can only identify distant secondaries of tycho where they occur in bright rays craters on mars and europa also formed large numbers of secondaries but under possibly ideal conditions for spallation as a mechanism to produce high velocity ejecta fragments the results from tycho show that large numbers of such fragments can be produced even from impact into a heavily fragmented target on which spallation is expected to be less important

interplay of rheology and entrainment in debris avalanches a numerical study flow type landslides are a major global hazard they occur worldwide and are responsible for a large number of casualties significant structural damage to property and infrastructure and economic losses the features of debris avalanches are particularly important as they involve open slopes and affect triangular source areas when initial slides turn into avalanches through further failures or eventual soil entrainment in this paper the propagation stage of debris avalanches is numerically modelled to provide information such as the propagation pattern of the mobilized material and its velocity thickness and run out distance the use of a depth integrated model has the following advantages i it adequately accommodates the irregular topography of real slopes which greatly affects the evolution of the propagation stage and ii it is less time consuming than full three dimensional approaches the model is named geoflow sph and has previously been applied to theoretical experimental and re

a study of a flowslide with significant entrainment in loess areas in china flowslides are a frequent type of natural disaster in loess areas and may result in the significant loss of properties and or casualties the dagou flowslide is a typical event in a loess area and is accompanied by significant sediment entrainment to analyze the mechanisms responsible for flowslides and to obtain the parameters for a runout analysis a field investigation was conducted specimens were sampled on site to carry out laboratory tests including a triaxial test sieve analysis and chemical component analysis the parameters were used in the runout study employing an energy based runout model an analytical entrainment model was adopted to calculate the entrainment after considering physical properties and the mechanism of the entrainment process of the loess finally the entrainment model was incorporated into the runout model to simulate the post failure process of this case energy dissipation due to the deformation of slices was considered as it was thought to be important for a slide with a significant deformation the simulation results were compared with the measurements including runout distance total volume erosion depth deposition height at different sections and velocities at specific locations the results indicate that the energy based runout model together with the entrainment model can capture the kinematic characteristics of the dagou flowslide therefore it is feasible to use this model to predict the runout characteristics of flowslides in similar areas copyright c 2017 john wiley sons ltd

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

a rational method for estimating maximum discharge of a landslide induced debris flow a case study from southwestern china this paper presents a rational method for estimating the maximum discharge of a landslide induced debris flow the method has five basic principles or steps a to identify and measure representative bends and straight zones along a channel through which a debris flow went down b to evaluate peak debris flow velocity in the bends c to assess peak debris flow velocity in the straight channel zones d to use the peak velocities to estimate the distribution of peak discharge along the entire channel and e to find the maximum velocity and discharge of the debris flow the method is illustrated with a case study of a landslide induced debris flow at a mountainous region near chengdu southwestern china the results show that the peak debris velocity was between 2 4 and 4 7 m s 1 and the peak debris discharge was between 6 7 and 35 7 m 3 s 1 the peak discharge initially increased at the upper portion of the channel then decreased at the lower portion indicating that the upper channel experienced erosion but the lower channel experienced deposition the location with the maximum debris flow discharge corresponds to the point where the volume of the debris flow started to decrease the method presented in this paper can help to prevent or mitigate debris flow hazards c 2006 elsevier b v all rights reserved

effects of entrainment phenomenon on the rapid and long runout movement of landslides in wenjia gully sichuan china as a common phenomenon in landslides entrainment of loose bed material along the sliding path can enhance both the volume and mobility of the sliding mass posing a great threat to the life and property safety of people in the affected area for the purpose of revealing the mechanism of entrainment phenomenon of sliding material in the runout process a dynamic slice based model was firstly proposed in the present study in this model the motion of landslide body is assumed to follow the rheological law proposed by voellmy additionally through voellmy model the increase in kinetic energy mass and volume of landslide body and entrainment depth caused by the entrainment phenomenon were taken into consideration subsequently on the basis of the dynamic slice based model back analyses were performed on the wenjia gully landslide the effect of entrainment phenomenon on the post failure motion was analyzed the calculated results shows that the travel distance obtained from proposed model is closer to field data than that resulted from scheidegger s empirical method moreover the peak value of the maximum velocity calculated by this model is in good agreement with that get from the dynamic analysis model dan3d when considering the entrainment phenomenon the volume of sliding mass increases greatly in post failure motion this paper provides a new method for analyzing the entrainment phenomenon in landslide motion

effects of the foot evolution on the behaviour of slow moving landslides the paper presents a time dependent 2d numerical model which has been developed with the purpose of highlighting the effects of the slope foot evolution on the behaviour of slow moving landslides the model allows to quantitatively analyse how foot mass variations can influence the stability and the movement rates of the landslide the landslide body is modelled as composed of two rigid blocks sliding on two different planes and interacting through a common boundary which position is assumed fixed during the analysis a finite difference approach is used to discretize the time for each time increment changes in model parameters are allowed including variations in shearing resistances groundwater level and block masses in order to simulate foot erosion during each iteration the overall stability of the system is checked computing the safety factor assuming that the percentage of mobilized shear strength is the same for the three surfaces if the system is not stable or if it is not at rest the velocity of the system is computed solving the momentum equations for the two blocks taking into account destabilising and resisting forces the mechanical interaction between the blocks and viscous components computed velocities are iteratively used to compute mass accumulation at the foot which in turn results in a change of the stability condition of the system examples are provided in order to highlight the roles of the model parameters finally the application to a real landslide vallcebre spain is presented which shows the advantage of considering the foot mass in the analysis of the displacement trends and the possibility to take into account the foot erosion in the long term behaviour of the slope

an unusually large debris flow at hummingbird creek mara lake british columbia on 11 july 1997 a very large debris flow occurred at hummingbird creek mara lake british columbia long term antecedent precipitation was record breaking whereas short term precipitation at salm

evaluation of approaches to calculate debris flow parameters for hazard assessment abstract many different runout prediction methods can be applied to estimate the mobility of future debris flows during hazard assessment the present article reviews the empirical analytical simple flow routing and numerical techniques all these techniques were applied to back calculate a debris flow which occurred in 1982 at la guingueta catchment in the eastern pyrenees a sensitivity analysis of input parameters was carried out while special attention was paid to the influence of rheological parameters we used the voellmy fluid rheology for our analytical and numerical modelling since this flow resistance law coincided best with field observations the simulation results indicated that the basal friction coefficients rather affect the runout distance while the turbulence terms mainly influence flow velocity a comparison of the velocity computed on the fan showed that the analytical model calculated values similar to the numerical ones the values of our rheological parameters calibrated at la guingueta agree with data back calculated for other debris flows empirical relationships represent another method to estimate total runout distance the results confirmed that they contain an important uncertainty and they are strictly valid only for the conditions which were the basis for their development with regards to the simple flow routing algorithm this methods could satisfactorily simulate the total area affected by the 1982 debris flow but it was not able to directly calculate total runout distance and velocity finally a suggestion on how different runout prediction methods can be applied to generate debris flow hazard maps is presented taking into account the definition of hazard and intensity the best choice would be to divide the resulting hazard maps into two types final hazard maps and preliminary hazard maps only the use of numerical models provided final hazard maps because they could incorporate different event magnitudes and they supplied output values for intensity calculation in contrast empirical relationships and flow routing algorithms or a combination of both could be applied to create preliminary hazard maps the present study only focussed on runout prediction methods other necessary tasks to complete the hazard assessment can be looked up in the guidelines for landslide susceptibility hazard and risk zoning included in this special issue

quantitative analysis of debris torrent hazards for design of remedial measures debris torrents which are rapid flows of soil and organic debris down steep mountain channels are a major natural hazard in many parts of british columbia a series of recent occurrences along the

reactivation characteristics and dynamic hazard prediction of an ancient landslide in the east margin of tibetan plateau the increasing human engineering activities and frequent extreme weather events have caused extensive reactivation of ancient landslides which are widely developed in the east margin of tibetan plateau the shangyaogou landslide as a typical ancient landslide example in this area was investigated to reveal the reactivation characteristics and its stability was calculated under the continuous rainfall condition with the intensity 30 mm day using the finite element software geo studio the whole movement process and hazard prediction under the different triggering conditions were simulated using the numerical software dan3d the study results showed that 1 under the joint influence of mw 7 9 wenchuan earthquake toe erosion and intensive rainfall multi stage deformations occurred to the front part of the shangyaogou landslide in multiple periods and also indicated a significant potential instability 2 under the continuous rainfall condition when the single effective total infiltration reached about 65 mm the reactivation part will become unstable while the single effective total infiltration reached about 120 mm both reactivation part and posterior part became instability 3 the maximum run out distance of the reactivation part was calculated to be 350 m and the forefront of the accumulation deposit would not reach the residential area when both parts failed simultaneously the maximum run out distance was calculated to be 550 m by considering the thickness and dynamic energy of the accumulation deposits and the vulnerable elements inside the fan area with radius of 150 m would be severely threatened 4 abundant earthquake triggered landslides have been developing in history or in recent years in the eastern margin of tibetan plateau some of them have been partly reactivated due to the increasing human engineering activities and extreme rainfall events and they have a potential for further deformation and failure the presented study methods can provide guidance for local disaster prevention and mitigation and can be used as a reference for the hazard prediction of the similar ancient landslides which have been reactivated

field experiments and numerical modeling of mass entrainment in snow avalanches 1 snow entrainment alters the speed and hence the run out distance of avalanches yet little is known about this significant process we studied entrainment in snow avalanches using observations from 1 the swiss vallee de la sionne test site 2 the italian pizzac site 3 catastrophic avalanches that occurred during the winter 1998 1999 in switzerland and 4 a medium sized spontaneous avalanche that occurred in 2000 in davos switzerland we determined mass and energy balances for 18 avalanche events on average the mass increased by a factor of 4 the primary mode of entrainment appeared to be frontal ploughing although entrainment behind the avalanche front was also observed step entrainment where a snow cover layer fractures and is entirely consumed by the avalanche also occurred basal erosion was negligible mass availability and snow cover structure were the limiting factors governing entrainment other factors such as track topography and avalanche dimension played a secondary role using the experimental results we introduced an entrainment model into a saint venant type flow model where the internal shear deformation of the avalanche is governed by a bagnold law and the shear stress at the basal layer is treated as a voellmy fluid the model with entrainment not only improves the prediction of the velocities and flow heights in comparison to measurements but also reproduces the variations in run out distances which characterize avalanches with similar terminal velocities but different masses

reconstruction of a destructive debris flow event via numerical modeling the role of valley geometry on flow dynamics debris flows are widespread natural phenomena characterized by high mobility high velocity and long runout distance and impact forces which frequently cause human casualties and significant damage to infrastructure to better understand the dynamics of such events analyzing in particular the effect induced by the valley geometry on flow velocity runout and mobilized volumes in this work we reconstruct a real debris flow event through numerical modeling specifically we used a modified version of the bing model a fluid dynamic depth integrated numerical model for debris flows which has been properly modified to account for width changes along the valley the studied event which occurred in scaletta zanclea messina north eastern sicily italy on october 1 2009 is exceptionally well constrained by field and topographic information in this respect the flow velocity estimated from two specific locations on the basis of field evidence the distribution of erosional and depositional areas along the racinazzo valley based on the comparison of pre and post event digital elevation models dems and the runout distance were used as constraints to calibrate the model furthermore we report a detailed description of the main event characteristics based on hydrological records and witness reports the numerical modeling results are consistent with witness reports and the severe damage recorded in the scaletta marina village and highlight the effect of the valley geometry on both the debris flow velocity and the erosion deposition processes the effect of changing valley width has been also quantified resulting in accelerations of the debris in correspondence of the valley narrowing and stagnations at the plateaus copyright 2015 john wiley sons ltd

an improved landslide mobility model a relatively simple and versatile numerical model known as dan developed by oldrich hungr for the assessment of landslide mobility has been enhanced to incorporate the consideration of a trapezoidal shaped flow channel for more realistic modelling purposes this enhanced debris mobility model dmm has been programmed to run on a spreadsheet and has been calibrated against detailed landslide data in hong kong in contrast to previous work the enhanced dmm eliminates the limitations inherited from the assumption of a rectangular flow channel with frictionless side boundaries when using dmm no predefined width of landslide is needed the dmm simulates landslide mobility with the flow resistance on the whole wetted perimeter of the channel calculates the surface width of the landslide based on the cross sectional geometry of the channel and is capable of predicting a lobe shaped debris deposition area this technical note presents details of the enhancement to the dan formulation key words landslides

basal shear stress of debris flow in the runout phase abstract a laboratory device is proposed to assess the basal shear stresses generated by debris flow mixtures during their runout phase the device consists of an inclinable box with a gate facing a deposition plane the box is filled with a selected debris flow mixture and after sudden opening of the gate the features of the dam break deposit can be measured based on some simplified assumptions of the energy balance a methodology is proposed to assess basal shear stresses the device has been tested using sediment samples from debris flow deposits generated by two catchments of the dolomites cortina d ampezzo belluno italy by carrying out runout tests for different sediment concentrations by volume the results show how the static coulomb friction law is valid in the runout phase with friction angles on the order of the angle of repose of the same material in dry conditions the data elaboration also yields an innovative constitutive equation for shear stresses this relation merges the coulomb mixture approach with the concept of a one phase flow with a certain rheology this integration offers a useful insight into the weaknesses of the rheological approach if it is not properly scaled up to the ambient pressure of interest

a sliding consolidation model for flow slides a model is proposed for the behaviour of flow slides in loose cohesionless materials in which the debris spreads out as a uniform sheet excess pore fluid pressures are assumed to be generated for example by undrained loading arising from the collapse of metastable structure in the source area of the flow slide under the influence of these the leading element of the debris moves downslope by basal sliding consolidating as it does so by single upward drainage as a result the pore pressure at the base of the element eventually decays to a value that brings the element to rest hence defining the run out of the flow slide the model is applicable in principle to subaqueous and subaerial flow slides and to pore fluids consisting of water gas or both of these the predictions of the model are tested against the observed behaviour and measured properties of the 1966 flow slide at aberfan south wales the results show that a sliding consolidation model provides a possible mechanism for that event

landslide risk assessment prediction of travel distance the geotechnical engineering office of hong kong database of landslides for the period 1984 1993 containing over 3000 landslide records and data for major landslides before this period were made

late holocene catastrophic slope collapse affected by deep seated gravitational deformation in flysch ropice mountain czech republic the region of the flysch western carpathians is characterized by abundant deep seated gravitational slope deformations dsgsds this study deals with a detailed analysis of late holocene catastrophic collapse of a fault created slope of mountain ropice in the moravskoslezske beskydy mountains eastern czech republic the catastrophic collapse was initialized by huge compound rotational slide toppling deformation which occurs on the upper part of the studied slope and affects tectonically weakened subhorizontally inclined sandstone beds detailed geomorphological mapping accompanied by morphotectonic analysis and geophysical sounding revealed at least two historic flowslides the older event f1 affected 0 5 0 8 mm3 of bedrock and created a 1000 m long and up to 150 m wide accumulation with abundant transverse steps and a carapace like surface the landslide toe blocked an adjacent valley which led to the development of a small impoundment with 4 m thick deposits containing lacustrine peat bog floodplain and alluvial fan facies radiocarbon dating and pollen analysis indicate the valley blockage at 1 5 ka bp the other flowslide f2 of much smaller dimensions 10 000 12 000 m3 overlaid the main landslide body and according to the dating of minerogenic horizon in the impoundment may have taken place 0 3 ka bp the organisation of landforms character of slope failures and dynamic back modelling point to a likely rock avalanche or combined rock slide debris avalanche mechanism of movement this case study shows that rapid rock avalanches can operate also in mountainous terrain with moderate relief if toppling together with deep seated gravitational deformation of slopes modifies the original stable position of bedding planes