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

empirical prediction of debris flow mobility and deposition on fans a new method to predict the runout of debris flows is presented a data base of documented sediment transporting events in torrent catchments of austria switzerland and northern italy has been compiled using common classification techniques with this data we test an empirical approach between planimetric deposition area and event volume and compare it with results from other studies we introduce a new empirical relation to determine the mobility coefficient as a function of geomorphologic catchment parameters the mobility coefficient is thought to reflect some of the flow properties during the depositional part of the debris flow event the empirical equations are implemented in a geographical information system gis based simulation program and combined with a simple flow routing algorithm to determine the potential runout area covered by debris flow deposits for a given volume and starting point of the deposits a monte carlo technique is used to produce flow paths that simulate the spreading effect of a debris flow the runout zone is delineated by confining the simulated potential spreading area in the down slope direction with the empirically determined planimetric deposition area the debris flow volume is then distributed over the predicted area according to the calculated outflow probability of each cell the simulation uses the arc objects environment of esri and is adapted to run with high resolution 2 5 m 2 5 m digital elevation models generated for example from lidar data the simulation program called toprundf is tested with debris flow events of 1987 and 2005 in switzerland copyright 2009 john wiley sons ltd

pitfalls in gpr data interpretation differentiating stratigraphy and buried objects from periodic antenna and target effects periodic events in ground penetrating radar gpr data may result from antenna and target effects rather than reflections from geologic features one of the most common pitfalls in gpr data interpretation is to identify each event on a radar cross section as scattering from a discrete horizon without considering other possible sources of these events soil electrical properties and surface roughness affect ground penetrating radar antenna radiation and waveform characteristics an impedance mismatch occurs over soils with electrical properties different than those for which the antennas were designed to perform optimally over and results in periodic ring down which can be misinterpreted as stratigraphy or multiple reflections in addition target resonance can introduce additional periodic features that can lead to misinterpretation in regards to the number of targets present co pole and cross pole antenna configurations can be combined with polarization dependent scattering characteristics of subsurface objects to recognize and reduce antenna ring down for improved imaging and interpretation

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

description and numerical modelling of the october 2000 nora debris flow northwestern italian alps the nora alluvial fan which is located in the orco river valley piedmont region italy was affected by a debris flow of approximately 10 000 m3 in october 2000 the event was triggered by heavy rainfall that affected the whole piedmont region at that time the mobilization of the water satured altered gneissic bedrock and colluvium in the upper zone of the nora basin resulted in the detachment of a debris slide which rapidly evolved into a channelized noncohesive debris flow as information from post event surveys and two pre event digital elevation models dems with different resolutions were available for the study site the dynamics of the event has been numerically back analyzed using the numerical code rash3d the obtained results have shown both the capability of the code to simulate the dynamics of a noncohesive debris flow including the final deposit depth distribution and the importance of on site surveys and digital elevation model dem resolution in interpreting numerical results and

landslides associated with spheroidally weathered mantle of granite porphyry induced by 2011 typhoon talas in the kii peninsula japan abstract typhoon talas brought heavy rain to the kii peninsula japan during 2 5 september 2011 causing hundreds of debris avalanches and debris flows in the southeastern part of the peninsula we undertook field investigations to understand the geological and geomorphological context of the landslides and found that the most important geological factor is spheroidal weathering of granite porphyry this granite porphyry is deeply weathered with corestones in higher elevations and forms low relief surfaces of which marginal areas were the major sources of debris avalanches corestones that failed were embedded in grus in situ or on nearby slopes of mudstone in which the granite porphyry intruded the corestones are made by spheroidal weathering from well developed columnar joints and sheeting joints sheeting joints in the source granite porphyry acted as sliding surfaces both before and during the occurrence of the 2011 debris avalanches

how unusual is the long runout of the earthquake triggered giant luanshibao landslide tibetan plateau china abstract in the tibetan plateau active tectonic deformation triggers frequent earthquakes and giant landslides associated with active faults produce serious consequences a study of the characteristics and mechanism of a historical long runout landslide in luanshibao lsb tibetan plateau china finds a maximum sliding distance l of 3 83 km with an elevation drop h of 820 m the landslide volume v was 0 64 0 94 10 8 m 3 and it produced a long runout h l 0 21 recent surface offset along the sinistral strike slip litang dewu fault passes through the middle part of the landslide which initiated on the hanging wall of the fault geological mapping geophysical prospecting trenching and 14 c dating together indicate that the lsb landslide occurred in jointed granite ca 1980 30 ybp probably triggered by a large earthquake compilation of volume and runout distance data for this landslide and other previously published data for volcanic and nonvolcanic long runout landslides yields a composite runout length volume relation l 12 52 v 0 37 that closely predicts runout of the lsb landslide although substantial variation is noted in runout length around the central tendency

the angle of reach as a mobility index for small and large landslides the relations between the angle of reach fahrboschung and other indexes expressing the mobility of landslides and vertical drop horizontal reach and volume of landslide mass have been analyzed by means of simplified plots and regression equations results for 204 landslides of all sizes show that whatever the mechanism of motion all kinds of landslides experience a continuous reduction of the angle of reach with volume increase this reduction starts from the smallest sizes scattering in this relation is mostly due to mechanisms of motion and to both obstacles and topographic constraints on the path this synthesis indicates that small landslides less than 0 5 106 m3 in relative terms display excesses of travel distance similar to large landslides since most small landslides are not expected to develop any change in the mechanism of progression while moving the decrease in the reach angle with volume suggests that scale effects should be taken into account the angle of reach is found to be

physical models of rock avalanche spreading behaviour with dynamic fragmentation the dynamic fragmentation of rock during avalanche motion has been postulated as a mechanism explaining the long runout of large rock avalanches or sturzstrome this paper investigates whether test

a slab on slab model for the flims rockslide swiss alps the flims rockslide is the largest landslide in the alps with an estimated volume of 12 km3 it resulted from a prehistoric high speed movement of a large limestone mass several main factors infl

detecting unfrozen sediments below thermokarst lakes with surface nuclear magnetic resonance 1 a talik is a layer or body of unfrozen ground that occurs in permafrost due to an anomaly in thermal hydrological or hydrochemical conditions information about talik geometry is important for understanding regional surface water and groundwater interactions as well as sublacustrine methane production in thermokarst lakes due to the direct measurement of unfrozen water content surface nuclear magnetic resonance nmr is a promising geophysical method for noninvasively estimating talik dimensions we made surface nmr measurements on thermokarst lakes and terrestrial permafrost near fairbanks alaska and confirmed our results using limited direct measurements at an 8 m deep lake we observed thaw bulb at least 22 m below the surface at a 1 4 m deep lake we detected a talik extending between 5 and 6 m below the surface our study demonstrates the value that surface nmr may have in the cryosphere for studies of thermokarst lake hydrology and their related role in the carbon cycle

a charcoal rich horizon at o69 greenland evidence for vegetation burning during the norse landnam it is often assumed that the colonisation of greenland by norse settlers in c a d 985 had a sudden and dramatic effect on the environment involving substantial vegetation clearance and environmental degradation consequently it has been argued that charcoal rich horizons visible in many sections in greenland represent the initial burning of the vegetation by norse farmers to create land suitable for agriculture in this study a charcoal rich layer visible in a modern drainage ditch beside the norse farm of o69 was analysed using archaeobotany sedimentary analysis and radiocarbon dating to test the date and formation processes of the horizon it is demonstrated that the charcoal rich layer at o69 was not derived from in situ vegetation burning in the 10th century and concluded that the layer was probably formed by the addition of midden material to the infields around o69 in the 13th and 14th centuries cal ad perhaps as part of a soil amendment strategy it is argued that caution must be exercised when interpreting charcoal rich horizons as time specific chronological markers in palaeoenvironmental sequences in greenland

a review of methods used to estimate initial landslide failure surface depths and volumes abstract this paper presents an overview of existing methods developed to characterize initial landslide failure surfaces and compute volumes based on surface information when it is buried this paper reviews the simplest models such as volume estimation based on ellipsoids and the information that can be obtained from surface displacement and morphology a simple method to define the volume of a rockslide using the identified discontinuities is also outlined the sloping local base level slbl which is able to automatically obtain a possible failure surface on the basis of a digital elevation model dem is described the balanced cross section methods applied to landslides are illustrated and can give the depth of the failure surface using predefined assumptions such as vector displacement parallel to the failure surface we can obtain an approximation of the failure surface either along translational or circular slides and this method can be improved by adding a mass balance equation recent work has also shown that using an inverse model a mass balance equation and assumptions about the rheology enables estimation of the failure surface these methods are illustrated with examples and they are applied to case studies and compared when the data available makes it possible the advantages and disadvantages of the methods are discussed this paper shows that the use high resolution topography and interpretation of the morphology is underexploited to extract information about failure surfaces geometry

presenting regional shallow landslide movement on three dimensional digital terrain abstract a storm can trigger numerous shallow landslides on hilly terrains this paper presents a distributed cell model for presenting regional shallow landslide movement on a three dimensional digital terrain the model consists of five components namely a digital terrain module a spatial rainfall distribution module an infiltration analysis module a slope stability evaluation module and a movement prediction module the locations and volumes of landslides are analyzed first through rainfall infiltration and slope stability analyses the detached material is assumed to move along the steepest path from one cell to a lower cell empirical equations that are developed based on local landslide inventories are adopted as a landslide movement cessation criterion the effect of landslide size on travel distance is considered by grouping unstable cells that are bounded at least at one side or corner the uncertainties in soil shear strength parameters and the landslide movement process are considered in determining the possible bounds of travel distance the movement analysis method is applied to a 164 5 km 2 hilly terrain in the wenchuan earthquake zone to test its performance in presenting regional shallow landslide movement the method predicts the volume of landslides reasonably well the observed and computed movement traces and deposition locations of the detached material also agree reasonably well the volume of individual landslide and travel distance may be substantially underestimated if the size effect is not considered

modelling landslide liquefaction mobility bifurcation and the dynamics of the 2014 oso disaster some landslides move slowly or intermittently downslope but others liquefy during the early stages of motion leading to runaway acceleration and high speed runout across low relief terrain mechanisms responsible for this disparate behaviour are represented in a two phase depth integrated landslide dynamics model that melds principles from soil mechanics granular mechanics and fluid mechanics the model assumes that gradually increasing pore water pressure causes slope failure to nucleate at the weakest point on a basal slip surface in a statically balanced mass failure then spreads to adjacent regions as a result of momentum exchange liquefaction is contingent on pore pressure feedback that depends on the initial soil state the importance of this feedback is illustrated by using the model to study the dynamics of a disastrous landslide that occurred near oso washington usa on 22 march 2014 alternative simulations of the event reveal the pronounced effects of a landslide mobility bifurcation t

linking rainfall induced landslides with debris flows runout patterns towards catchment scale hazard assessment abstract debris flows and landslides induced by heavy rainfall represent an ubiquitous and destructive natural hazard in steep mountainous regions for debris flows initiated by shallow landslides the prediction of the resulting pathways and associated hazard is often hindered by uncertainty in determining initiation locations volumes and mechanical state of the mobilized debris and by model parameterization we propose a framework for linking a simplified physically based debris flow runout model with a novel landslide hydro mechanical triggering lht model to obtain a coupled landslide debris flow susceptibility and hazard assessment we first compared the simplified debris flow model of perla 1980 with a state of the art continuum based model ramms and with an empirical model of rickenmann 1999 at the catchment scale the results indicate that predicted runout distances by the perla model are in reasonable agreement with inventory measurements and with the other models predictions of localized shallow landslides by lht model provides information on water content of released mass to incorporate effects of water content and flow viscosity as provided by lht on debris flow runout we adapted the perla model the proposed integral link between landslide triggering susceptibility quantified by lht and subsequent debris flow runout hazard calculation using the adapted perla model provides a spatially and temporally resolved framework for real time hazard assessment at the catchment scale or along critical infrastructure roads railroad lines

geomorphic hazard assessment of landslide dams in south westland new zealand fundamental problems and approaches abstract quantitative assessments of landslide hazard usually employ empirical heuristic deterministic or statistical methods to derive estimates of magnitude frequency distributions of landsliding the formation and failure of landslide dams are common geomorphic processes in mountain regions throughout the world causing a series of consequential off site hazards such as catastrophic outburst floods debris flows backwater ponding up and downstream aggradation and channel instability conceptual and methodological problems of quantifying geomorphic hazard from landslide dams result from a aspects of defining landslide dam magnitude b scaling effects i e the geomorphic long range and long term implications of river blockage and c paucity of empirical data geomorphic hazard from a landslide dam break flood on the basis of conditional probabilities is being analysed for the alpine south westland region of new zealand where formation and failure of landslide dams is frequent quantification of the annual probability of landsliding and subsequent dam formation in the area is limited by historical and only partially representative empirical data on slope instability since landslide dam stability is a major control governing the potential of catastrophic outburst flooding the ensuing hazard is best assessed on a recurring basis gis based modelling of virtual landslide dams is a simple and cost effective approach to approximate site specific landslide dam and lake dimensions reservoir infill times and scaled magnitude of potential outburst floods although crude these order of magnitude results provide information critical to natural hazard planning mitigation or emergency management decisions

contribution of dendrochronology to the determination of magnitude frequency relationships for landslides abstract the determination of magnitude frequency m f relationships is necessary for landslide hazard assessment ideally this is achieved by using inventories of past landslide events recorded by technical units or aerial photo interpretation however direct sources of landslide data are often unavailable dendrogeomorphological techniques allow us to determine the frequency of events but few attempts have been made to estimate landslide magnitude by analysing the spatial distribution of disturbed trees this paper addresses m f determination for rockfalls debris flows and complex slides obtained by dendrogeomorphology the cases presented require the appropriate understanding of both the geomorphological context and the disturbance caused by landslide motion on trees both small and large rockfalls can be identified and dated by reconstructing the trajectories in the forest stand the larger the rockfall size the longer the path the higher the number of affected trees and the greater the area of deposition of rock fragments the area of damaged trees is proposed as an indicator of the rockfall magnitude the frequency and extent of a series of debris flows were reconstructed by mapping their deposits using relative dating criteria and by dating damaged trees local and global mudslide reactivations were deduced by sampling various tree generations and by analysing the location of the disturbed trees in the landslide units magnitude cumulative frequency curves were determined for the three cases

the aureole of olympus mons mars as the compound deposit of submarine landslides abstract the enigmatic deposits building up the olympus mons aureole on mars are likely among the largest landslide remnants in the solar system these deposits exhibit an extraordinary run out distance up to nearly 700 km in spite of a fall height some 100 times smaller after quantifying the mobility of the olympus mons aureole lobes it is suggested based on dynamical considerations and morphological analysis that the aureole could be the consequence of a series of gigantic subaqueous landslides in order to bring evidence in favor of this interpretation comparisons are drawn between the different landslide deposits on earth and mars emphasizing the similarity with the rock avalanches of the canary islands and the hawaii the results of experimental subaqueous debris flows are also analyzed and numerical calculations are introduced to simulate the dynamics of flow in analogy with certain subaqueous landslides on earth it is possible that the outstanding run out of the aureole lobes was a consequence of hydroplaning a natural lubrication by water during flow

waterborne gpr survey for estimating bottom sediment variability a survey on the po river turin italy we conducted an integrated geophysical survey on a stretchoftheriverpoinordertocheckthegprabilitytodiscriminate the variability of riverbed sediments through an analysis of the bottom reflection amplitudes we conducted continuousprofileswitha200 mhzgprsystemandahandheld broadband em sensor aconductivity meter and a tdr provided punctual measurements of water conductivity permittivity andtemperature theprocessingandinterpretation ofthegem 2andgprdatawereenhancedbyreciprocalresults and by integration with the punctual measurements of the em properties of the water we used a processing flow thatimprovedtheradargramimagesandpreservedtheamplitude ratios among the different profiles and the frequency content at the bottom reflection signal we derived the water attenuationcoefficientbothfromthepunctualmeasurements using the maxwell formulas and from the interpretation of the gpr data finding an optimal matching between the two values the gpr measurements provided maps of the bathymetry and of the bottom reflection amplitude the high reflectivity of the riverbed derived from the gpr interpretation agreed with the results of the direct sampling campaign that followed the geophysical survey the variability of the bottom reflection amplitudesmap whichwasnotconfirmed by the direct sampling could also have been caused by scatteringphenomenaduetotheriverbedclastswhicharedimensionallycomparabletothewavelengthoftheradarpulse

gis assisted modelling for debris flow hazard assessment based on the events of may 1998 in the area of sarno southern italy part i maximum run out based on the debris flow events that occurred in may 1998 in the area of sarno southern italy this paper presents an approach to simulate debris flow maximum run out on the basis of the flow source areas and an average thickness of 1 2 m of the scarps we estimated debris flow volumes of the order of 104 and 105 m3 flow mobility ratios h l derived from the x y z coordinates of the lower most limit of the source areas i e apex of the alluvial fan and the distal limit of the flows ranged between 0 27 and 0 09 we performed regression analyses that showed a good correlation between the estimated flow volumes and mobility ratios this paper presents a methodology for predicting maximum run out of future debris flow events based on the developed empirical relationship we implemented the equation that resulted from the calibration as a set of gis macros written in visual basic for applications vba and running within arcgis we carried out sensitivity analyses and observed that hazard mapping with this methodology should attempt to delineate hazard zones with a minimum horizontal resolution of 0 4 km the developed procedure enables the rapid delineation of debris flow maximum extent within reasonable levels of uncertainty it incorporates sensitivities and it facilitates hazard assessments via graphic user interfaces and with modest computing resources copyright 2007 john wiley sons ltd

tree ring based assessment of rockfall frequency on talus slopes at sola d andorra eastern pyrenees abstract the determination of the frequency of rockfall events continues to challenge quantitative hazard assessments in most mountain areas dendrogeomorphological analysis was used to assess rockfall frequency on talus slopes at sola d andorra eastern pyrenees andorra rockfall events were dated at two sites one at the outlet of a chute and the other below a rock wall the impact wounds visible on the tree surface were analyzed with a seasonal temporal resolution at each site trees were sampled in three forest strips 15 to 30 m wide located at different heights on the talus all the trees with visible injuries in the strips were sampled rockfall frequency cannot be assessed by a simple analysis of time series of tree damage a satisfactory assessment requires a prior interpretation of the location of the damaged trees in relation to a number of rockfall events at sola d andorra the rockfall chronology was reconstructed for the last 25 years by dating visible wounds for older periods the tree wound record of rockfalls is incomplete owing to progressive closure of wounds wounds exceeding 40 years in age had already disappeared from the tree surface in the study area our results show a clear reduction of the rockfall frequency down the talus a noticeable lateral change in frequency and an influence of source morphology chute or wall on rockfall activity on the talus

a conceptual model of supra glacial lake formation on debris covered glaciers based on gpr facies analysis jordan r mertes acknowledges funding from michigan technological university and the michigan technological university 2016 fall finishing fellowship sarah s thompson acknowledges funding from the university centre in svalbard unis and the european commission fp7 mc ief

palaeoecological and historical evidence for manuring and irrigation at garðar igaliku norse eastern settlement greenland palaeoenvironmental data are presented from the site of gar ar modern igaliku the location of the cathedral and the bishop s farm in the norse eastern settlement of greenland the latter was founded from c ad 985 and abandoned some time during the fifteenth century inspection of drainage ditches located in close proximity to the settlement ruins revealed inter alia an organic rich unit containing cultural debris worked wood animal bone stone and charcoal dated by ams radiocarbon dates on seeds to the period c ad 1110 1370 fossil insect and pollen assemblages contained within the deposit appear representative of natural environments primarily wet eutrophic meadows but are mixed with high frequencies of a range of synanthropic insects including human and animal ectoparasites that could only derive from indoor habitats this is strongly indicative of the manuring of fields with waste from houses and byres in order to increase yields of hay large amounts of hay would have been necessary to prov

the beinn alligin rock avalanche nw scotland cosmogenic 10be dating interpretation and significance a tongue of very coarse rockslide debris that extends 1 25km downvalley below beinn alligin in nw scotland has been variously interpreted as a glacier cored rock glacier landslide debris redistributed by glacier ice or an excess runout landslide exposure dating with cosmogenic 10be demonstrates that the the debris mass was emplaced at 3950 320 yr bp and therefore was not associated with glacier ice calculations based on frictional considerations imply that the feature is an excess runout rock avalanche sturzstrom deposit the morphological characteristics of the deposit appear consistent with movement by grainflow or fragmental flow failure is inferred to reflect time dependent paraglacial stress release and consequent propagation of an internal joint network but may have been triggered by seismic activity the late holocene age of failure implies persistence of the e ects of paraglacial stress release over a time scale of several millennia

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

geohazards of slope mass movement and its prevention in hong kong rapid urban development in hilly terrain coupled with tropical storms with heavy rainfall has led to the frequent occurrence of disastrous landslides in hong kong this paper outlines several case histories of such disastrous landslides in hong kong and the major efforts that have been made to mitigate landslide hazards in hong kong since the mid 1970s factors that contributed to such landslides and their causative mechanisms are analyzed methods of predicting the runout distance and lateral extent of rainfall induced slope failures are summarized slope maintenance requirements and stabilization measures are delineated including the stabilization of loose fill slopes

environmental responses of past and recent agropastoral activities on south greenlandic ecosystems through molecular biomarkers paleoenvironmental studies previously performed on lake igaliku revealed two agropastoral phases in south greenland the norse settlement from ad 986 to ca ad 1450 and the recent installation of sheep farmers since the 1920s to improve the knowledge of the timing and magnitude of the greenlandic agropastoral activities a lipid inventory was realized and compared with biological and geochemical data during the 12th century a major increase in deoxycholic acid doc and coprophilous fungal spores revealed a maximum of herbivores synchronously a minimum of the n c29 n c31 alkane ratio and tree and shrub pollen and a maximum of triterpenyl acetates showed a reduction in the tree and shrub cover because of grazing activities lupanone produced by angiosperms appeared simultaneously in the molecular content probably revealing an introduction of plant species by the norse as it has been the case for rumex spp no major erosion was recorded by trimethyl tetrahydrocrysenes tthcs and titanium ti fl

observations of grain scale interactions and simulation of dry granular flows in a large scale flume a series of 30 tests on dry granular flows were performed using a large scale flume under varying source volumes and basal friction conditions to capture grain scale interactions and their impact o

phase structure of radar stratigraphic horizons within antarctic firn we have recorded reflection profiles of firn through large areas of west antarctica and part of the east antarctic plateau using 400 mhz short pulse radar the locations show accumulation rates that vary from well above to well below the vertical radar resolution most reflection horizons have extensive lateral continuity and are composed of distinctive wavelets with a consistent phase polarity sequence within their successive half cycles we modeled these waveforms and conclude that they arise from thin double layers of ice over hoar which is consistent with the standard model of firn stratification in addition we conclude that ice hoar layers are extensive throughout west antarctica and also present although more sparsely beneath the antarctic plateau

problematic but promising ponds palaeoenvironmental evidence from the norse eastern settlement of greenland pollen and related proxy based studies of human environment interactions during the norse and later periods within greenland have primarily involved the investigation of peat lake and soil deposits all of which have taphonomic and sampling problems many small ponds exist but they seem to have been relatively ignored in investigations of palaeoecologically based environmental history to evaluate their usefulness for studies of ecologically related cultural history especially where sites are in intimate association with the archaeology a pond in the norse eastern settlement has been examined to investigate three principal questions i does such a site contain a useful record of environmental history ii does it offer a record of sufficient resolution and sensitivity for the study of anthropogenic landscape impacts iii are there any apparent drawbacks to these sequences using data obtained from palynological diatom sedimentological and radiocarbon analyses it is concluded that environmental data for each proxy aside from 14c dating are clearly capable of being explained in a reasonably straightforward and compatible manner and fulfil the hopes for the sampling medium copyright 2011 john wiley sons ltd

can the collapse of a fly ash heap develop into an air fluidized flow reanalysis of the jupille accident 1961 a fly ash heap collapse occurred in jupille liege belgium in 1961 the subsequent flow of fly ash reached a surprisingly long runout and had catastrophic consequences its unprecedented degree of fluidization attracted scientific attention as drillings and direct observations revealed no water saturated zone at the base of the deposits scientists assumed an air fluidization mechanism which appeared consistent with the properties of the material in this paper the air fluidization assumption is tested based on two dimensional numerical simulations the numerical model has been developed so as to focus on the most prominent processes governing the flow with parameters constrained by their physical interpretation results are compared to accurate field observations and are presented for different stages in the model enhancement so as to provide a base for a discussion of the relative influence of pore pressure dissipation and pore pressure generation these results show that the apparently high diffusion coefficient that characterizes the dissipation of air pore pressures is in fact sufficiently low for an important degree of fluidization to be maintained during a flow of hundreds of meters

gis assisted modelling for debris flow hazard assessment based on the events of may 1998 in the area of sarno southern italy ii velocity and dynamic pressure the velocity and dynamic pressure of debris flows are critical determinants of the impact of these natural phenomena on infrastructure therefore the prediction of these parameters is critical for hazard assessment and vulnerability analysis we present here an approach to predict the velocity of debris flows on the basis of the energy line concept first we obtained empirically and field based estimates of debris flow peak discharge mean velocity at peak discharge and velocity at channel bends and within the fans of ten of the debris flow events that occurred in may 1998 in the area of sarno southern italy we used this data to calibrate regression models that enable the prediction of velocity as a function of the vertical distance between the energy line and the surface despite the complexity in morphology and behaviour of these flows the statistical fits were good and the debris flow velocities can be predicted with an associated uncertainty of less than 30 and less than 3 m s 1 we wrote code in visual basic for applications vba that runs within arcgis to implement the results of these calibrations and enable the automatic production of velocity and dynamic pressure maps the collected data and resulting empirical models constitute a realistic basis for more complex numerical modelling in addition the gis implementation constitutes a useful decision support tool for real time hazard mitigation copyright 2008 john wiley sons ltd

sph run out modelling of channelised landslides of the flow type abstract rainfall induced channelised landslides of the flow type may reach high velocities and travel large run out distances the proper modelling of the propagation stage is fundamental to risk analysis and management the correct selection of mass rheology is fundamental to this procedure and the variation of pore water pressures and bed entrainment along the landslide path must also be properly taken into account all of these processes can be consistently simulated through a quasi 3d depth integrated coupled sph model in this study such a model is applied to a relevant case history from southern italy for which an advanced dataset is available the numerical results provide a satisfactory back analysis of the case history and clearly indicate that the bed entrainment rate and the extent of the erodible areas affect the propagation paths the velocities and the deposition heights on the basis of the results general insights into this type of landslide are discussed with reference to different hypotheses for propagation modelling

airborne river ice thickness profiling with helicopter borne uhf short pulse radar l objet de cette etude est d evaluer la capacite d un radar aeroporte dans la mesure d epaisseur de glace de riviere

influence of topography and volume on mobility of loess slides within different slip surfaces mobility of loess slides has been evaluated using an empirical approach based on a detailed field investigation and remote sensing image interpretation for all the loess slides the affected area increases with increasing loess slides volume from the statistical analysis it is seen that the travel distance has an increasing trend while the coefficient of friction has a decreasing trend with the increase in landslide volume landslide volume determine its travel distance and coefficient of friction that can be shown with a regression equation having simple power law form which indicates that the mobility of loess slides increases with increasing volumes by analogy the greater the energy of the sliding loess mass the stronger is the mobility of loess slide a plot of the travel distance of loess slide versus fall height shows a significant positive power law correlation indicating the increase in mobility of loess slide with fall height the negative power law correlation observed between the travel distance and slope inclination implies that the mobility decreases with the increase of slope inclination three datasets of loess slides characterized by different slip surfaces were distinguished the red clay contact landslides have the strong mobility than landslides in loess and bedrock contact

target interaction with stratigraphy beneath shallow frozen lakes quarter wave resonances within gpr profiles resonances within ground penetrating radar gpr reflection profiles recorded over shallow frozen lakes located onanartilleryandbombingrangeininterioralaskaoriginate near ice bottom and freeze thaw interface horizons and are similar to those caused by shallow utilities the transmitted pulse spectra were centered near 280 mhz low pass filteringdifferentiatestheresonancesfrombackgroundscattering thetransittimesbetweentheironsetandthatoftheoverlying interface reflections correspond with spectral peaks predicted for layers with thickness of one in situ quarter wavelength which we call quarter wave resonance the peaks are below 160 mhz which is well below the transmitted pulse bandwidth and may occur as a modulation of a reflection sequence although the transit times cannot resolve both layer thickness and permittivity reasonable values of permittivity give overburden layers above the targets on the order of 10 cm which is consistent with the persistence of the resonances numerical models of metal objects beneath an interface between materials of strong permittivity contrast reveal that significant energy at the predicted frequencies requires cylinderdiameterstoolargetobeordnance however strong resonances at the predicted frequencies result fromflat metal sheets of 0 5 1 m dimension and so we interpret the resonances to be caused by nonhazardous targets late winter is an ideal time to survey for targets in this area because the ice affords repeatable positioning for the antennas and thermal high dielectric contrast interfaces are then well developed thebandwidthofthepulseweusedappearsideallysuitedfor bothresolutionoftheshallowstrataanddetectionoftheresonances thereby allowing the resonances to be checked againstquarter wavetheory

comparison of rockfall susceptibility assessment at local and regional scale a case study in the north of beijing china this study shows a rockfall susceptibility assessment at local scale in north beijing of china including the identification of rockfall sources onsite by terrain and rock discontinuities analysis and run out distance prediction by rocfall simulation two types of rockfall were defined including one type on the cliffs with long inclined slopes and another type on the road slopes with low height two historical rockfall events were used to back calibrating the parameters used for run out distance simulation based on the work rockfall susceptibility map at local scale was created in gis which was compared with the map obtained at regional scale entire huairou district scale due to the difference of approaches applied procedure of assessment and types of source data acquired the two resulting rockfall susceptibility maps are proved to be different still both of them are useful and could be used at different level s decision for rockfall prevention and mitigation different types of uncertainties exist in the study of rockfall susceptibility assessment to reduce the uncertainties studies on both approaches and techniques are suggested

evaluating volume of coseismic landslide clusters by flow direction based partitioning abstract a strong earthquake can trigger thousands of co seismic landslides the evaluation of the volume of such co seismic landslides is essential for landslide risk assessment and long term post earthquake hazard evaluation empirical volume area power laws are often applied to estimate the landslide volume when several small landslide deposits form a large cluster on the hillslope blurry boundaries of the clustered co seismic landslides may lead to seemingly one large landslide and grossly overestimated landslide volume in this paper we propose a flow direction based method to identify the boundaries of a cluster of landslides and to partition co seismic landslides three watersheds that were severely impacted by co seismic landslides in the wenchuan earthquake region are chosen for case studies each co seismic landslide cluster in these watersheds was interpreted from images taken shortly after the earthquake and partitioned into individual landslides in accordance with a flow direction map that is processed based on a local digital terrain model finally the volume of each individual landslide is calculated using an empirical volume area power law the adopted power law scaling relationship is selected from six widely used empirical relations and verified by 11 local landslide cases the proposed flow direction based partitioning method is further verified by clear boundaries of landslides that were exposed after storms as well as supplementary field survey results the proposed method results in similar landslide boundaries and volumes as the field survey results the uncertainty of this approach is below 19 if no partitioning is conducted the total volume of the landslide cluster can approach twice that from the field investigations

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 2500 year record of natural and anthropogenic soil erosion in south greenland the environmental impact of the norse landnam in greenland has been studied extensively but to date no study has quantified the soil erosion that norse agricultural practices are believed to have caused to resolve this problem a high resolution sedimentary record from lake igaliku in south greenland is used to quantitatively reconstruct 2500 years of soil erosion driven by climate and historical land use an accurate chronology allows for the estimation of detritic fluxes and their uncertainties land clearance and the introduction of grazing livestock by the norse around 1010 ad caused an acceleration of soil erosion up to 8 mm century in 1180 ad which is two fold higher than the natural pre landnam background from 1335 ad to the end of the norse eastern settlement in the mid fifteenth century the vegetation began to recover from initial disturbance and soil erosion decreased after an initial phase of modern sheep breeding similar to the medieval one the mechanization of agriculture in the 1980s caused an unprecedented soil erosion rate of up to 21 mm century five times the pre anthropogenic levels independently a suite of biological and geochemical proxies including ti and diatom concentrations c n ratio 13c and 15n of organic matter confirm that the medieval and modern anthropogenic erosion far exceeds any natural erosion over the last 2500 years our findings question the veracity of the catastrophic scenario of overgrazing and land degradation considered to have been the major factor responsible for norse settlement demise they also shed light on the sustainability of modern practices and their consequences for the future of agriculture in greenland

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

gpr characterization of a lacustrine uxo site we used 135 mhz ground penetrating radar gpr reflection profiles to determine if high explosive he depth bombs were possibly detonated within a small new england lake formerly used as a bombing range as well as the depths and distribution of inert and possibly unexploded ordnance uxo within the subbottom sediments maximum water depth was 8 6 m the primary munitions were unarmed practice bombs but terrestrial fragments from he depth bombs led us to seek stratigraphic obliteration and distortion as evidence of their use the low water conductivity and quartz rich sediments provided more than 8 m of subbottom penetration beneath slope and shelf sediments the high permittivities of the water and subbottom sediments provided good antenna directivity excellent 2d migrations multicentimeter vertical resolution and a unique pulse waveform signature for metal objects our line profiles revealed hundreds of subbottom diffractions which implied an areal distribution of thou sands of suspicious object

landslide characteristics and slope instability modeling using gis lantau island hong kong steep terrain and high a frequency of tropical rainstorms make landslide occurrence on natural terrain a common phenomenon in hong kong this paper reports on the use of a geographical information systems gis database compiled primarily from existing digital maps and aerial photographs to describe the physical characteristics of landslides and the statistical relations of landslide frequency with the physical parameters contributing to the initiation of landslides on lantau island in hong kong the horizontal travel length and the angle of reach defined as the angle of the line connecting the head of the landslide source to the distal margin of the displaced mass are used to describe runout behavior of landslide mass for all landslides studied the horizontal travel length of landslide mass ranges from 5 to 785 m with a mean value of 43 m and the average angle of reach is 27 7 this gis database is then used to obtain a logistic multiple regression model for predicting slope instability it is indicated that slope gradient lithology elevation slope aspect and land use are statistically significant in predicting slope instability while slope morphology and proximity to drainage lines are not important and thus excluded from the model this model is then imported back into the gis to produce a map of predicted slope instability the results of this study demonstrate that slope instability can be effectively modeled by using gis technology and logistic multiple regression analysis