postglacial topographic evolution of glaciated valleys a stochastic landscape evolution model the retreat of valley glaciers has a dramatic effect on the stability of glaciated valleys and exerts a prolonged influence on the subsequent fluvial sediment transport regime we have studied the evolution of an idealized glaciated valley during the period following retreat of ice using a numerical model the model incorporates a stochastic process to represent deepseated landsliding non linear diffusion to represent shallow landsliding and an approximation of the bagnold relation to represent fluvial sediment transport it was calibrated using field data from several recent surveys within british columbia canada we present ensemble model results and compare them with results from a deterministic linear diffusion model to show that explicit representation of large landslides is necessary to reproduce the morphology and channel network structure of a typical postglacial valley our model predicts a rapid rate of fluvial sediment transport following deglaciation with a subsequent gradual decline similar to that inferred for holocene time we also describe how changes in the model parameters affect the estimated magnitude and duration of the paraglacial sediment pulse

erosional power in the swiss alps characterization of slope failure in the illgraben landslides and rockfalls are key geomorphic processes in mountain basins their quantification and characterization are critical for understanding the processes of slope failure and their contributions to erosion and landscape evolution we used digital photogrammetry to produce a multi temporal record of erosion 1963 2005 of a rock slope at the head of the illgraben a very active catchment prone to debris flows in switzerland slope failures affect 70 of the study slope and erode the slope at an average rate of 0 39 0 03 m yr the analysis of individual slope failures yielded an inventory of 2500 failures ranging over 6 orders of magnitude in volume despite the small slope area and short study period the slope failures form a characteristic magnitude frequency distribution with a rollover and a power law tail between 200 m and 1 6 106 m with an exponent of 1 65 slope failure volume scales with area as a power law with an exponent of 1 1 both values are low for studies of bedrock landslides and rockfall and result from the highly fractured and weathered state of the quartzitic bedrock our data suggest that the magnitude frequency distribution is the result of two separate slope failure processes type 1 failures are frequent small slides and slumps within the weathered layer of highly fractured rock and loose sediment and make up the rollover type 2 failures are less frequent and larger rockslides and rockfalls within the internal bedded and fractured slope along pre determined potential failure surfaces and make up the power law tail rockslides and rockfalls of high magnitude and relatively low frequency make up 99 of the total failure volume and are thus responsible for the high erosion rate they are also significant in the context of landscape evolution as they occur on slopes above 45 and limit the relief of the slope copyright 2012 john wiley sons ltd

comparing rockfall scar volumes and kinematically detachable rock masses scenario based risk assessment for rockfalls requires assumptions for different scenarios of magnitude volume the magnitude of such instabilities is related to the properties of the jointed rock mass with the characteristics of the existing unfavourably dipping joint sets playing a major role the critical factors for the determination of the maximum credible rockfall volume in a study site the forat negre in andorra are investigated the results from two previous analyses for the rockfall size distribution at this site are discussed the first analysis provides the observed size distribution of the rockfall scars and it is an empirical evidence of past rockfalls the second one calculates the kinematically detachable rock masses indicating hypothetical rockfalls that might occur in the future the later gives a maximum rockfall volume which is one order of magnitude higher because the persistence of the basal planes is overestimated the tension cracks and lateral planes interrupt systematically the basal planes exerting a control over their persistence and restricting the formation of extensive planes and large rockfall failures nonetheless the formation of basal planes across more than one spacings of tension cracks is possible and small step path failures have been observed too concluding the key factor for the determination of the maximum credible volume at the study site is the maximum realistic length of the basal planes penetrating into the rock mass their spacing and if applied the contribution of the rock bridges to the overall rock mass resistance

effects of bedrock landslides on cosmogenically determined erosion rates abstract the successful quantification of long term erosion rates underpins our understanding of landscape formation the topographic evolution of mountain ranges and the mass balance within active orogens the measurement of in situ produced cosmogenic radionuclides crns in fluvial and alluvial sediments is perhaps the method with the greatest ability to provide such long term erosion rates although deep seated bedrock landsliding is an important erosional process in active orogens its effect on crn derived erosion rates is largely unquantified we present a numerical simulation of cosmogenic nuclide production and distribution in landslide dominated catchments to address the effect of bedrock landsliding on erosion rates results of the simulation indicate that the temporal stability of erosion rates determined from crn concentrations in sediment decreases with increased ratios of landsliding to bedrock weathering rates within a given catchment area and that as the frequency of landsliding increases larger catchment areas must be sampled in order to accurately evaluate long term erosion rates in addition results of this simulation suggest that sediment sampling for crns is the appropriate method for determining long term erosion rates in regions dominated by mass wasting processes whereas bedrock surface sampling for crns may generally underestimate long term erosion rates response times of crn concentrations to changes in erosion rate indicate that climatically driven cycles of erosion may be detected but that complete equilibration of crn concentrations to new erosional conditions may take tens of thousands of years comparison of simulated crn derived erosion rates with a new data set of such rates from the nepalese himalaya underscore the conclusions drawn from the model results

sediment transfer by shallow landsliding in the queen charlotte islands british columbia despite the importance of landsliding in routing sediment through mountainous drainage basins few studies have documented landsliding rates over extended time and space scales we have investigated landsliding in surficial material in the queen charlotte islands using a large inventory of events derived from aerial photography covering an area of 166 7 km 2 the mean erosion rate for shallow landsliding is 0 10 mm a 1 which is at the upper end of shallow landsliding rates observed in the pacific northwest and coastal british columbia but several orders of magnitude lower than rock based landsliding rates reported in the literature probability distributions for landslide area and volume are somewhat convex in form flattening of the curve found at low magnitudes may be due to sampling bias or physical mechanisms inhibiting failure and the steepening for high values may exist because the sampling period is not long enough to adequately represent large events landslides generally initiate on hillslope gradients greater than 0 50 0 60 the largest numbers of landslides occur on south to southwest facing slopes and east to northeast facing slopes most events occur on concave and straight hillslopes in upper slope positions landsliding rates were found not to be af fected by rock type hillslopes in the queen charlotte islands are often mantled by weathered quaternary deposits and hence landsliding events are not directly controlled by weathering of bedrock about 31 of landslides identified in this study deposited material in stream reaches with about 83 of these landslides deposited in reaches with gradients between 3 and 10 resume malgre la grande contribution des glissements de terrain a acheminer des sediments a travers des bassins de drainage montagneux peu d etudes ont documente les taux de glissements de terrain sur une longue periode de temps et sur de grandes superficies nous avons fait des recherches sur des glissements de materiaux de surface dans les iles de la reine charlotte en utilisant un grand inventaire d evenements tires de photographies aeriennes couvrant une re

analyses of past and present rock slope instabilities in a fjord valley implications for hazard estimations abstract for quantitative hazard assessment it is necessary to define the magnitude frequency distribution and a temporal model of the landslide frequency this is often complicated for large rock slope failures due to the lack of significant numbers of large rock slope failures in inventories of a given homogeneous region or sparse information about the timing an inventory of 108 rock slope failure deposits within the fjords of the storfjord region including a relative rockslide chronostratigraphy was available for this study the temporal distribution of rock slope failures is characterized by a rapid response with a high frequency of failures directly after deglaciation followed by a lower constant frequency since 9 000 years bp for the entire storfjord region the largest recorded volumes failed directly after deglaciation volumes larger than 5 10 6 m 3 have not been recorded within the last 9 000 years in addition 17 rockslide scars and on the other hand 17 potential rock slope instabilities have been mapped at the northeastern flank of tafjord which is a branch of the storfjord volume frequency relations have been developed for the three inventories from tafjord comprising i fjord deposits ii rockslide scars and iii potential instabilities they result in very similar distributions over the entire volume range all three inventories are underlying the same processes that lead to destabilisation and finally failure additionally the compilation of the three inventories is independent and based on different methodologies the similarity of the volume frequency distributions is thus verifying the different inventories hence the obtained volume frequency relation can be used to assess the rockslide hazard for the study area present day annual expectable frequencies for different volume classes have been assessed based on the obtained volume frequency relation of the fjord deposits for example the average annual frequency for rock slope failures of v 1 10 6 m 3 originating from the northeastern flank of tafjord is 1 1670 based on a lognormal distribution this regional hazard can be used to improve previously existing qualitative susceptibility rankings for potential unstable rock slopes within the tafjord region the resulting probabilities are very low however the uncertainties of all hazard estimates are very high

structural and thermal controls of rockfall frequency and magnitude within rockwall talus systems swiss alps both from a systemic and natural hazard perspective it is essential to understand the causes and frequency of rockfalls in mountain terrain and to predict the block sizes deposited at specific locations commonly rockfalls are studied either retrospectively using talus slopes or directly by rockwall surveys nevertheless our understanding of rockfall activity particularly at the lower magnitude spectrum is still incomplete moreover the explanatory framework is rarely addressed explicitly in this study we investigate two rockwall talus systems in the swiss alps to estimate the rockfall frequency magnitude pattern and their key controls we present a holistic approach that integrates deductive geotechnical and thermal investigations of the source rockwalls with abductive talus based explanations of rockfall volume and frequency the rockwalls three dimensional 3d joint pattern indicates that 75 of the blocks may be released as debris fall 14 m3 and boulder falls 14 61 m3 which is mirrored in the corresponding talus material using two year records of near surface rockwall temperatures as input for a 1d heat conduction model underlines the destabilizing role of seasonal ice segregation deepest frost cracking of 300 cm may occur on the north northeast nne exposed snow rich rockwall with peaks at the outermost surface the synthesis of all data suggests that infrequent large planar slides approximately every 250 years overlain by smaller more frequent wedge and toppling failures approximately every 17 50 years as well as high frequency flake like clasts 3 6 events year characterize the rockfall frequency magnitude pattern at hungerli peak here we argue that small size rockfalls need more scientific attention particularly in discontinuous permafrost zones our study emphasizes that future frequency magnitude research should ideally incorporate site specific structural and thermal properties rather than just focusing on climatic or meteorological triggers we discuss how holistic rockwall talus approaches as proposed here could help to increase our process understanding of rockfalls in mountain environments copyright 2017 john wiley sons ltd

the effects of slope length and slope gradient on the size distributions of loess slides field observations and simulations abstract in this study we characterize and consider the effects of slope length and slope gradient on the size distributions of loess slides to carry out this study we employ data on 275 loess slides within zhidan county central loess plateau china these data were collected in the field and supplemented by the interpretation of remote sensing images both the field observations and slope stability analysis show that loess slide size increases with the slope length slide sizes is significantly correlated with slope length showing a power law relationship in both cases however the simulation results show that slope gradient is not associated with loess slide size the main part of the link between slope gradient and slide size seen in the observations is only apparent as indicated by the strong connection between slope gradient and length statistical analysis of the field observations reveals that slope gradient decreases with increasing slope length and this correlation interferes with the potential relationship between landslide sizes and slope gradient seen in the field observations in addition the probability densities of the areas of loess slides occurring on slopes of different slope lengths are determined using kernel density estimation this analysis shows that slope length controls the rollover of the frequency size distribution of loess slides the scaling exponent increases with slope length

debris flows as a factor of hillslope evolution controlled by a continuous or a pulse process flood effectiveness observations imply that two families of processes describe the formation of debris flow volume one is related to the rainfall erosion relationship and can be seen as a gradual process and one is related to additional geological geotechnical events those named hereafter extraordinary events in order to discuss the hypothesis of coexistence of two modes of volume formation some methodologies are applied firstly classical approaches con sisting in relating volume to catchments characteristics are considered these approaches raise questions about the quality of the data rather than providing answers concerning the controlling processes secondly we consider statistical approaches cumulative number of events distribution and cluster analysis and these suggest the possibility of having two distinct families of processes however the quantitative evaluation of the threshold differs from the one that could be obtained from the first approach but they all agree in the sense of the coexistence of two families of events thirdly a conceptual model is built exploring how and why debris flow volume in alpine catch ments changes with time depending on the initial condition sediment production the model shows that large debris flows i e with important volume are observed in the beginning period before a steady state is reached during this second period debris flow volume such as is observed in the beginning period is not observed again integrating the results of the three approaches two case studies are presented showing 1 the possibility to observe in a catchment large volumes that will never happen again due to a drastic decrease in the sediment availability sup porting its difference from gradual erosion processes 2 that following a rejuvenation of the sediment storage by a rock avalanche the magnitude frequency relationship of a torrent can be differentiated into two phases the beginning one with large and frequent debris flow and a later one with debris flow less intense and frequent supporting the results of the conceptual model although the results obtained cannot identify a clear threshold between the two families of processes they show that some debris flows can be seen as pulse of sediment differing from that expected from gradual erosion

frequency and hazard of large rock avalanches in the central southern alps new zealand forty two rock avalanche deposits with volumes ranging from a chosen lower threshold of 1 10 6 m 3 up to 500 10 6 m 3 have been identified in a 10 000 km 2 area of the central southern alps new zealand the observed frequency of one per 244 yr over 10 250 yr is biased by erosion a nearly complete sample of the past 1 700 yr indicates a frequency of 1 per 94 yr on the average the largest rock avalanche in any century is 56 10 6 m 3 and in any millennium 103 10 6 m 3 at about one per century most large rock avalanches are probably triggered by large earthquakes and only a few by large storms the risk of rock avalanche debris reaching a specified distance from a source of known elevation is given by a simple stochastic model locally calibrated to assess rock avalanche hazard

earthquake induced chains of geologic hazards patterns mechanisms and impacts large earthquakes initiate chains of surface processes that last much longer than the brief moments of strong shaking most moderate and large magnitude earthquakes trigger landslides ranging from small failures in the soil cover to massive devastating rock avalanches some landslides dam rivers and impound lakes which can collapse days to centuries later and flood mountain valleys for hundreds of kilometers downstream landslide deposits on slopes can remobilize during heavy rainfall and evolve into debris flows cracks and fractures can form and widen on mountain crests and flanks promoting increased frequency of landslides that lasts for decades more gradual impacts involve the flushing of excess debris downstream by rivers which can generate bank erosion and floodplain accretion as well as channel avulsions that affect flooding frequency settlements ecosystems and infrastructure ultimately earthquake sequences and their geomorphic consequences alter mountain landscapes over both human and geologic time scales two recent events have attracted intense research into earthquake induced landslides and their consequences the magnitude m 7 6 chi chi taiwan earthquake of 1999 and the m 7 9 wenchuan china earthquake of 2008 using data and insights from these and several other earthquakes we analyze how such events initiate processes that change mountain landscapes highlight research gaps and suggest pathways toward a more complete understanding of the seismic effects on the earth s surface

generating event based landslide maps in a data scarce himalayan environment for estimating temporal and magnitude probabilities abstract event based landslide maps display landslide events of different magnitudes that are associated with a single major trigger event based landslide maps allow the estimation of spatio temporal probabilities of landslide events that are required for the assessment of landslide hazard in this paper we discuss the generation of event based landslide inventory maps for a region in darjeeling himalayas india with limited historical landslide information we used eight different sets of source data spanning the period from 1968 to 2007 which include topographic maps satellite images and post event field maps for each period we mapped the various landslide types and calculated landslide density and activity in individual terrain units to analyze changes in the spatial behavior of landslides through time for the assessment of the temporal landslide probability we used landslide event days and associated daily and antecedent rainfall amounts in a multivariate statistical analysis to model the temporal relationship between landslide events and the amount of triggering rainfall for estimating the magnitude probability we applied magnitude frequency analysis for the different event based landslide maps using landslide area m2 as a proxy despite the incompleteness of the source data sets used the resulting landslide inventory maps can be used successfully in determining temporal and magnitude probabilities of future landslides

identifying rock slope failure precursors using lidar for transportation corridor hazard management abstract in the thompson and fraser river valleys rockfall and rockslides are a hazard for railway traffic in the region in june 2013 a 2600 m 3 rockslide occurred in the white canyon causing damage to infrastructure and interruption to service in the year preceding this failure the slope was monitored using terrestrial light detection and ranging lidar as part of the railway ground hazards research program initiative the purpose of this study is to evaluate a hazard management strategy for transportation corridors exposed to steep slopes involving the identification of rockfall precursors prior to significant slope failures for this failure deformation was observed in the seven months preceding collapse with an accelerating period occurring in the final 28 days a distinct pattern of smaller rockfalls was observed around the perimeter of the deforming rock block as well as loss of surficial material over the slides tension crack this study shows that with lidar monitoring precursors to rock slope failures can be identified allowing for better rock slope hazard management by focusing attention on areas with the highest probability of failure

effects of debris flow magnitude frequency distribution on avulsions and fan development shifts in the active channel on a debris flow fan termed avulsions pose a large threat because new channels can bypass mitigation measures and cause damage to settlements and infrastructure recent but limited field evidence suggests that avulsion processes and tendency may depend on the flow size distribution which is difficult to constrain in the field here we investigate how the flow magnitude frequency distribution and the associated flow magnitude sequences affect avulsion on debris flow fans we created three experimental fans with contrasting flow size distributions 1 a uniform distribution 2 a steep double pareto distribution with many flows around the mean and a limited number of large flows and 3 a shallow double pareto distribution with fewer flows around the mean and more abundant large flows the fan formed by uniform flows developed through regular sequences of stepwise channelization backstepping of deposition toward the fan apex and avulsion over multiple flows in contrast the wide range of sizes in the double pareto distributions led to distinct avulsion mechanisms and fan evolution here large flows could overtop channels creating levee breaches that could initiate avulsion immediately or in subsequent events moreover sequences of small to moderately sized flows could deposit channel plugs triggering avulsion in the next large flow this mechanism was most common on the fan formed by a steep double pareto distribution but was rare on the fan formed by a shallow double pareto distribution where large flows were more frequent we infer that some flow size distributions are more likely to cause avulsions especially those that produce abundant sequences of small flows followed by a large flow critically avulsions in our experiments could occur by either large single events or over multiple flows this observation has important implications for hazard assessment on debris flow fans suggesting that attention should be paid to flowhistory as well as flow size

characteristics of large landslides in sensitive clay in relation to susceptibility hazard and risk the clay plains of the saint lawrence lowlands of eastern north america are subject to large landslides in sensitive clay these landslides occur relatively infrequently but can have very signific

slope stability evaluation using back propagation neural networks the yudonghe landslide located in western hubei province of china consists of eastern and western subunits as well as a main landslide mass with upper and lower slip surfaces as an important landslide close to shuibuya dam on the qing river its stability is crucial as the slide might reactivate because of a change in ground water level caused by filling of the shuibuya reservoir existing weakness zones growth of ruptures the downslope attitude of geologic strata and water infiltration which reduced the strength of rocks and soils have been found to be the most important factors contributing to the yudonghe landslide with regard to the landslide processes it can be noted that the original large scale slide activity was due to erosion by the qing river the second sliding resulted from the fall of blocks from the head scarp and the final activity was the growth of the eastern and western secondary slides a base failure was the main type of slope movement however it was obvious that more than one sliding event occurred as inferred from striations and fractures detected by microstructure analysis of soils along the failure surfaces slope instability was evaluated by the method of back propagation neural networks bpnn in which a four layer bpnn model with five input nodes two hidden layers and two output nodes was constructed using a training data set of landslide samples throughout the qing river area the predicted results of this analysis showed that the factor of safety was 1 10 which indicates that the yudonghe landslide is currently in a marginally stable condition

the assessment of rockfall hazard at the base of talus slopes fragmental rockfall is characterized by the independent movement of individual rock fragments after detachment from a rock face the continued operation of the process leads to the accumulation of talus slopes on talus slopes the rockfall shadow extends beyond the base of the talus and consists of scattered boulders that have run out beyond the base of the slope the landing probability of boulders in the shadow is examined return periods of the order of 1000 years relative to a house site are typical rockfall behaviour particularly with respect to run out into the shadow can be assessed using geological evidence empirical methods physical modelling and computer based analytical models an empirical minimum shadow angle of 27 5 i e the angle between the distal limit of the shadow and the top of the talus slope is suggested and would be useful in rockfall vulnerability studies at the base of talus slopes as a first approximation to shadow limits it is preferable to the use of the rockfall fahrb

improving sinkhole hazard models incorporating magnitude frequency relationships and nearest neighbor analysis abstract this work presents a methodology for elaborating sinkhole hazard models that incorporate the magnitude and frequency relationships of the subsidence process the proposed approach has been tested in a sector of the ebro valley mantled evaporite karst where sinkholes largely induced by irrigation practices have a very high occurrence rate 50 sinkholes km 2 yr in this area covering 10 km 2 a total of 943 new cover collapse sinkholes were inventoried in 2005 and 2006 multiple susceptibility models have been generated analyzing the statistical relationships between the 2005 sinkholes and different sets of variables including the nearest sinkhole distance the quantitative evaluation of the prediction capability of these models using the 2006 sinkhole population has allowed the identification of the method and variables that produce the most reliable predictions the incorporation of the indirect variable nearest sinkhole distance has contributed significantly to increase the quality of the models despite simplifying the modeling process by using categorical rather than continuous variables the best susceptibility model generated with the total sinkhole population and the selected method and variables has been transformed into a hazard model that provides minimum estimates of the spatial temporal probability of each pixel to be affected by sinkholes of different diameter ranges this transformation has been carried out combining two equations derived from the more complete 2006 sinkhole population one of them expressing the expected spatial temporal probability of sinkhole occurrence and the other the empirical magnitude and frequency relationships generated for two different types of land surfaces which control the strength of the surface layer and the size of the sinkholes the presented method could be applied to predict the spatial temporal probability of events with different magnitudes related to other geomorphic processes e g landslides

emergent characteristics of rockfall inventories captured at a regional scale high resolution rockfall inventories captured at a regional scale are scarce this is partly owing to difficulties in measuring the range of possible rockfall volumes with sufficient accuracy and completeness and at a scale exceeding the influence of localised controls this paucity of data restricts our ability to abstract patterns of erosion identify longterm changes in behaviour and assess how rockfalls respond to changes in rock mass structural and environmental conditions we have addressed this by developing a workflow that is tailored to monitoring rockfalls and the resulting cliff retreat continuously in space in 3d and over large spatial scales 10 4 m we tested our approach by analysing rockfall activity along 20 5 km of coastal cliffs in north yorkshire uk in what we understand to be the first multi temporal detection of rockfalls at a regional scale we show that rockfall magnitude frequency relationships which often underpin predictive models of erosion are highly sensitive to the spatial extent of monitoring variations in rockfall shape with volume also imply a systemic shift in the underlying mechanisms of detachment with scale leading us to question the validity of applying a single probabilistic model to the full range of rockfalls observed here finally our data emphasise the importance of cliff retreat as an episodic process going forwards there will a pressing need to understand and model the erosional response of such coastlines to rising global sea levels as well as projected changes to winds tides wave climates precipitation and storm events the methodologies and data presented here are fundamental to achieving this marking a step change in our ability to understand the competing effects of different processes in determining the magnitude and frequency of rockfall activity and ultimately meaning that we are better placed to investigate relationships between process and form erosion at critical regional scales

geology of giant gas fields in china twenty five gas fields with recognized ultimate recoveries larger than 25 billion cubic meters have been found in six basins in china the earliest was found in 1959 and the latest in 2005 recognition of more recent discoveries as giants will probably further increase the population examination of reservoir age lithology trap and depositional environment leads to the conclusion that there are no diagnostic characteristics common to all of the giants however coaly source rocks traps in close proximity to major gas kitchens reservoirs and caprocks with reasonable quality late gas accumulation and continuous gas supply are the preferred parameters uncommonly thick reservoir rocks or unusual development of porosity and permeability are not required the fact that giant gas fields exist in reasonable numbers and have been discovered steadily through the years suggests that more efforts are needed to find the remaining gas resources in china

statistical analysis of rockfall volume distributions implications for rockfall dynamics we analyze the volume distribution of natural rockfalls on different geological settings i e calcareous cliffs in the french alps grenoble area and granite yosemite cliffs california sierra and different volume ranges i e regional and worldwide catalogs contrary to previous studies that included several types of landslides we restrict our analysis to rockfall sources which originated on subvertical cliffs for the three data sets we find that the rockfall volumes follow a power law distribution with a similar exponent value within error bars this power law distribution was also proposed for rockfall volumes that occurred along road cuts all these results argue for a recurrent power law distribution of rockfall volumes on subvertical cliffs for a large range of rockfall sizes 102 1010 m3 regardless of the geological settings and of the preexisting geometry of fracture patterns that are drastically different on the three studied areas the power law distribution for rockfall volumes could emerge from two types of processes first the observed power law distribution of rockfall volumes is similar to the one reported for both fragmentation experiments and fragmentation models this argues for the geometry of rock mass fragment sizes to possibly control the rockfall volumes this way neither cascade nor avalanche processes would influence the rockfall volume distribution second without any requirement of scale invariant quenched heterogeneity patterns the rock mass dynamics can arise from avalanche processes driven by fluctuations of the rock mass properties e g cohesion or friction angle this model may also explain the power law distribution reported for landslides involving unconsolidated materials we find that the exponent values of rockfall volume on subvertical cliffs 0 5 0 2 is significantly smaller than the 1 2 0 3 value reported for mixed landslide types this change of exponents can be driven by the material strength which controls the in situ topographic slope values as simulated in numerical models of landslides densmore et al 1998 champel et al 2002 index terms 5104 physical properties of rocks fracture and flow 1815 hydrology erosion and sedimentation 8122 tectonophysics dynamics gravity and tectonics

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

space time landslide predictive modelling abstract landslides are nearly ubiquitous phenomena and pose severe threats to people properties and the environment in many areas investigators have for long attempted to estimate landslide hazard in an effort to determine where when or how frequently and how large or how destructive landslides are expected to be in an area this information may prove useful to design landslide mitigation strategies and to reduce landslide risk and societal and economic losses in the geomorphology literature most of the attempts at predicting the occurrence of populations of landslides by adopting statistical approaches are based on the empirical observation that landslides occur as a result of multiple interacting conditioning and triggering factors based on this observation and under the assumption that at the spatial and temporal scales of our investigation individual landslides are discrete point events in the landscape we propose a bayesian modelling framework for the prediction of the spatio temporal occurrence of landslides of the slide type caused by weather triggers we build our modelling effort on a log gaussian cox process lgcp by assuming that individual landslides in an area are the result of a point process described by an unknown intensity function the modelling framework has two stochastic components i a poisson component which models the observed random landslide count in each terrain subdivision for a given landslide intensity i e the expected number of landslides per terrain subdivision which may be transformed into a corresponding landslide susceptibility and ii a gaussian component used to account for the spatial distribution of the local environmental conditions that influence landslide occurrence and for the spatio temporal distribution of unobserved latent environmental controls on landslide occurrence we tested our prediction framework in the collazzone area umbria central italy for which a detailed multi temporal landslide inventory covering the period from before 1941 to 2014 is available together with lithological and bedding data we subdivided the 79 km2 area into 889 slope units sus in each su we computed the mean and standard deviation of 16 morphometric covariates derived from a 10 m 10 m digital elevation model for 13 lithological and bedding attitude covariates obtained from a 1 10 000 scale geological map we computed the proportion of each thematic class intersecting the given su we further counted how many of the 3 379 landslides in the multi temporal inventory affect each su and grouped them into six periods we used this complex space time information to prepare five models of increasing complexity our baseline model mod1 carries the spatial information only through the covariates mentioned above it does not include any additional information about the spatial and temporal structure of the data and it is therefore equivalent to the predominantly used landslide susceptibility model in the literature the second model mod2 is analogous but it allows for time interval specific regression constants our next two models are more complex in particular our third model mod3 also accounts for latent spatial dependencies among neighboring sus these are inferred for each of the six time intervals to explain variations in the landslide intensity and susceptibility not explained by the thematic covariates by contrast our fourth model mod4 accounts for the latent temporal dependence separately for each su disregarding neighboring influences ultimately our most complex model mod5 contextually features all these relations it contains the information carried by morphometric and thematic covariates six time interval specific regression constants and it also accounts for the latent temporal effects between consecutive slope instabilities at specific sus as well as the latent spatial effects between adjacent sus we also show that the intensity is strongly related to the aggregated landslide area per su because of this our most complex model largely fulfills the definition of landslide hazard commonly accepted in the literature at least for this study area we quantified the spatial predictive performance of each of the five models using a 10 fold cross validation procedure and the temporal predictive performance using a leave one out cross validation procedure we found that mod5 performed better than the others we then used it to test a novel strategy to classify the model results in terms of both landslide intensity and susceptibility which provides more information than traditional susceptibility zonations for land planning and management hereafter we use the term traditional simply to refer to the majority of modelling procedures in the literature we discuss the advantages and limitations of the new modelling framework and its potential application in other areas making specific and general hazard and geomorphological considerations we also give a perspective on possible developments in landslide prediction modelling and zoning we expect our novel approach to the spatio temporal prediction of landslides to enhance the currently limited ability to evaluate landslide hazard and its temporal and spatial variations we further expect it to lead to better projections of future landslides and to improve our collective understanding of the evolution of complex landscapes dominated by mass wasting processes under multiple geophysical and weather triggers

significance of rockfall magnitude and carbonate dissolution for rock slope erosion and geomorphic work on alpine limestone cliffs reintal german alps abstract the proportional contribution of low mid and high magnitude rock slope failure orchestrates rock slope erosion and rockfall hazard in alpine and arctic environments in this study we compare sediment yield geomorphic work and rock wall retreat of carbonate dissolution and five different magnitudes of rock slope failure in the steep alpine reintal trough valley we combine a four year rockfall collector measurement of 140 mg of fragmental rockfall a 20th century scientific record of mid magnitude rockfall as well as carbon dating and a historical record of 15th to 19th century rock avalanche activity the total rockfall sediment yield of 8 6 3 4 10 3 m 3 year 1 is dominated by high magnitude rock avalanches 10 6 m 3 62 and low magnitude debris falls 3 18 while mid magnitude boulder block and cliff falls are less important the magnitude signal contradicts studies on siliceous rocks where mid magnitude rockfall dominates rock slope erosion the geomorphic work released in the 17 3 km 2 large catchment by rockfalls 123 47 w km 2 i e 0 38 0 15 mm year 1 and solute transport 34 18 w km 2 i e 0 05 0 03 mm year 1 exceeds previously published alpine values by one to multiple orders of magnitude we hypothesise that the magnitude signal of enhanced small and high magnitude rockfall is characteristic for carbonate cliffs the elevated porosity related susceptibility to fragmentation and persistent carbonate dissolution along potential sliding planes are likely to favour both low and high magnitude rock slope failures here we show how the magnitude signal of rock slope failure influences rock wall retreat geomorphic work rockfall deposition and sediment connectivity

rockfall triggering by cyclic thermal stressing of exfoliation fractures exfoliation of rock deteriorates cliffs through the formation and subsequent opening of fractures which in turn can lead to potentially hazardous rockfalls although a number of mechanisms are known to trigger rockfalls many rockfalls occur during periods when likely triggers such as precipitation seismic activity and freezing conditions are absent it has been suggested that these enigmatic rockfalls may occur due to solar heating of rock surfaces which can cause outward expansion here we use data from 3 5 years of field monitoring of an exfoliating granite cliff in yosemite national park in california usa to assess the magnitude and temporal pattern of thermally induced rock deformation from a thermodynamic analysis we find that daily seasonal and annual temperature variations are sufficient to drive cyclic and cumulative opening of fractures application of fracture theory suggests that these changes can lead to further fracture propagation and the consequent detachment of rock our data indicate that the warmest times of the day and year are particularly conducive to triggering rockfalls and that cyclic thermal forcing may enhance the efficacy of other more typical rockfall triggers some rockfalls occur without obvious triggers such as seismicity or freeze thaw conditions temperature and deformation patterns on a granite cliff suggest that cyclical thermal forcing can progressively open fractures and trigger rockfalls

earthquake induced rockfall hazard zoning abstract a methodology for quantitative probabilistic hazard zonation for earthquake induced rockfalls is presented and demonstrated in the area of friuli eastern italian alps affected by the 1976 mw 6 5 earthquake four rockfall datasets have been prepared both from historical data analysis and field surveys the methodology relies on a three dimensional hazard vector whose components include the rockfall kinetic energy the fly height and the annual frequency the values of the first two components are calculated for each location along the slope using the 3d rockfall runout simulator hy stone the rockfall annual frequency is assessed by multiplying the annual onset frequency by the simulated transit frequency the annual onset frequency is calculated through a procedure that combines the extent of unstable areas calculated for 10 different seismic hazard scenarios with different annual frequencies of occurrence and the magnitude relative frequency relationship of blocks as derived from the collected field data for each annual frequency of occurrence the unstable area is calculated as a function of morphometric and earthquake characteristics a series of discriminant analysis models using the rockfall datasets and dems of different resolution 1 and 10 m identified the controlling variables and verified the model robustness in contrast with previously published relationships we show that the slope curvature plays a relevant role in the computation of the unstable area

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

patterns of precursory rockfall prior to slope failure in this paper we examine data generated using high resolution three dimensional laser scanning monitoring of coastal rock cliffs these data are used to identify spatial and temporal patterns in rockfall activity behavior prior to slope failure analysis of the data suggests that given sufficient measurement precision precursory behavior here manifest as the rate of rockfall activity prior to failure can be detected measured and monitored environmental conditions appear to have a diminishing influence on the occurrence of increasingly large slope failures the monitoring data implies a time dependent sequence in the occurrence of smaller rockfalls in the period leading to the largest failures recorded this behavior is attributed to the mechanisms of strain accumulation in the rock mass resulting from brittle failure of the slope the implication is that combining these data with models of failure mechanisms may allow failure time to be forecast from wide area monitoring of precursory behavior these findings have implications for the management of potentially unstable slopes the understanding of slope failure mechanisms and the generation of a new type of slope failure warning systems

quantifying 40 years of rockfall activity in yosemite valley with historical structure from motion photogrammetry and terrestrial laser scanning abstract rockfalls and rockslides are often dominant geomorphic processes in steep bedrock landscapes but documenting their occurrence can be challenging requiring frequent monitoring and well resolved spatial data repeat application of remote sensing methods such as terrestrial laser scanning tls and structure from motion sfm photogrammetry can detect even very small rockfalls but typically these acquisitions span only years and may not record rockfall activity representative of longer term rates of cliff erosion inventory databases can extend rockfall records but are commonly incomplete and prone to observation bias we employed tls and sfm on two adjacent cliffs el capitan and middle brother in yosemite valley integrating semi annual data collections from 2010 to 2017 with historical archival sfm models derived from oblique photographs taken in 1976 comparing the 1976 sfm models against more recent data allows for more accurate and precise rockfall detection and volume measurement over a 40 year period change detection indicates that 235 rockfalls occurred from the two cliffs more than twice as many events as are recorded in yosemite s inventory database although individual rockfall volumes reported in the inventory database vary from those measured by sfm tls reported cumulative volumes are similar to measured volumes likely because the large volume events that account for most of the cumulative volume tend to be widely observed and well documented volume frequency relationships indicate that the cliffs erode predominantly by less frequent larger volume rockfalls at rates of 0 9 to 1 7 mm yr our study demonstrates how integrated sfm and tls measurements especially utilizing sfm models derived from historical imagery allow detection and quantification of rockfalls spanning several decades complementing and improving inventory databases informing rockfall hazard assessment and providing longer term rates of cliff erosion

from landslide susceptibility to landslide frequency a territory wide study in hong kong abstract rain induced shallow landslide is the major type of landslide that happens on natural terrain in hong kong due to its high seasonal rainfall and deep weathering soil profile the geotechnical engineering office has been in a leading role to steer the risk management of natural terrain landslides in hong kong recently the territory wide rainfall based landslide susceptibility model in terms of landslide density per year has been developed to predict the number of natural terrain landslides that may occur in an anticipated rainfall event subsequently the storm based landslide density has been transformed to the annual landslide frequency to compile the territory wide landslide frequency map by incorporating the mean annual frequency of occurrence of different probable rainfall scenarios the annual rainfall frequency of a particular rainfall scenario is derived from its return period determined based on the abundant real time rainfall data at a five minute interval from 110 automatic raingauges across hong kong at an average density of 10 km2 gauge the transformation is discussed in this paper together with the evaluation of the performance of the landslide frequency map in addition the potential applications of the map in hong kong and the pitfalls of the common evaluation methods including the receiver operating characteristic curve and the success rate curve are highlighted

impacts of fracturing patterns on the rockfall susceptibility and erosion rate of stratified limestone abstract the erosion of steep rock slopes is largely controlled by rockfalls which are a relevant hazard in mountainous regions the deposition of blocks allows us to quantify rockfall activities and analyze the fracturing pattern that is the key to understand the processes that result in rockfalls at monte generoso in southern switzerland we compared the calculated rockfall susceptibility with the measured rockfall activity for a thinly stratified limestone cliff area thus we were able to determine the erosion rate for the past 40 years and verify the reliability of the method used to perform the rockfall susceptibility analysis the geomorphology of the area and the fracturing pattern have been accurately analyzed and quantified in the field and using airborne laser scanning techniques these results have been used to perform a rockfall susceptibility assessment based on the frequency of joints and the distribution of failure mechanisms five joint sets have been detected and the large influence of wedge sliding is demonstrated the emptying works carried out on a series of protective barriers and nets resulted in detailed data regarding the magnitude distribution of the blocks that fell over a period of 40 years this information coupled with the inventory of the present day rock slope instabilities results in a method that can be used to correct the erosion rate power laws have been fit with the blocks and instability data then several calibration options have been tested to consider the additional amounts of erosion due to larger and less frequent potential rockfall events the rockfall susceptibility calculated with the distribution of the failure mechanisms is correlated well with the measured rockfall activity this approach allows us to characterize the erosion processes in a steep geomorphological context to obtain new insights regarding the evolution of rock slopes

dynamic rockfall risk analysis abstract rockfall is a dangerous hazard on steep and susceptible slope however it is not easy to identify potential rockfalls on cliff mountains traditionally rockfall risk analysis ignores the temporal evolution of risk due to the changes of the elements at risk or changes in the annual probability this may lead to an underestimation of risk in time in this paper we present an innovative approach for a dynamic risk analysis and we demonstrate this approach for the shenxianjju scenic area case study where rockfall represent a threat for thousands of tourists each year moreover we studied the role of rock mass quality in controlling the rockfall potential and rockfall volume since this may lead to significant changes of rockfall risk in space we describe the use of unmanned aerial vehicle terrestrial lidar and detailed field surveys to identify 34 potential rockfalls on slopes where historical rockfalls have occurred within ignimbrite and rhyolite rock masses rockfall blocks range in size between large and very large andesite derived rockfalls are characterized by medium size to large block size faulted and fractured ignimbrite and rhyolite rock masses within the fault damage zone exhibit small very small rockfall block sizes based on the identified potential rockfalls in the study area we quantified the dynamic risk by considering the temporal spatial changes of tourist activity to demonstrate the methodology two potential rockfalls on two heavily used tourist routes were selected for these scenarios we quantified the annual probability of occurrence the reach probability the dynamic temporal spatial probability and the vulnerability of tourists the dynamic temporal probability was also calculated considering different visiting periods e g working days weekends holidays showing significant changes in the risk level among the different visiting periods and with time some of the investigated scenarios were within the alarp zone in the first years i e pll on workday in 2017 2019 and subsequently became unacceptable i e pll on workday in 2020 as a conclusion the research demonstrates that the traditional static risk analysis would lead to a significant rockfall risk underestimation

evaluation of anfis and lr models for seismic rockfalls susceptibility mapping a case study of firooz abad kojour iran earthquake 2004 seismic rockfall is one of the prevalent geohazards that cause huge losses in the earthquake stricken areas in the present research a model is developed to map susceptibility occurrence probability of seismic rockfalls in a regional scale using logistic regression lr and adaptive neuro fuzzy inference system anfis techniques in this research firooz abad kojour earthquake of 2004 was introduced as the benchmark and the model base the susceptible zones predicted by lr and anfis methods were compared with the database distribution map of seismic rockfalls by which the results revealed a good overlapping between the susceptible zones predicted by the anfis and the field observation of rockfalls triggered by this earthquake besides for the statistical evaluation of results obtained by lr and anfis models the verification parameters with high accuracy such as density ratio dr quality sum qs and receiver operating characteristic curve roc were used by analyzing the susceptibility maps and considering the qs index obtained by lr 21 04184 and anfis 26 75592 it could be found that the qs of anfis is higher than that of lr moreover based on the obtained value of the area under the curve auc from lr 0 972 and anfis 0 984 methods anfis provided a higher accuracy in zonation and susceptibility mapping of rockfalls triggered by firooz abad kojour earthquake of 2004 compared to the lr method

a review of assessing landslide frequency for hazard zoning purposes abstract the probability of occurrence is one of the key components of the risk equation to assess this probability in landslide risk analysis two different approaches have been traditionally used in the first one the occurrence of landslides is obtained by computing the probability of failure of a slope or the reactivation of existing landslides in the second one which is the objective of this paper the probability is obtained by means of the statistical analysis of past landslide events specifically by the assessment of the past landslide frequency in its turn the temporal frequency of landslides may be determined based on the occurrence of landslides or from the recurrence of the landslide triggering events over a regional extent hazard assessment using frequency of landslides which may be taken either individually or collectively requires complete records of landslide events which is difficult in some areas its main advantage is that it may be easily implemented for zoning frequency assessed from the recurrence of landslide triggers does not require landslide series but it is necessary to establish reliable relations between the trigger its magnitude and the occurrence of the landslides the frequency of the landslide triggers can be directly used for landslide zoning however because it does not provide information on the spatial distribution of the potential landslides it has to be combined with landslide susceptibility spatial probability analysis to perform landslide hazard zoning both the scale of work and availability of data affect the results of the landslide frequency and restrict the spatial resolution of frequency zoning as well magnitude frequency relationships are fundamental elements for the quantitative assessment of both hazard and risk

automatic detection of alpine rockslides in continuous seismic data using hidden markov models data from continuously recording permanent seismic networks can contain information about rockslide occurrence and timing complementary to eyewitness observations and thus aid in construction of robust event catalogs however detecting infrequent rockslide signals within large volumes of continuous seismic waveform data remains challenging and often requires demanding manual intervention we adapted an automatic classification method using hidden markov models to detect rockslide signals in seismic data from two stations in central switzerland we first processed 21 known rockslides with event volumes spanning 3 orders of magnitude and station event distances varying by 1 order of magnitude which resulted in 13 and 19 successfully classified events at the two stations retraining the models to incorporate seismic noise from the day of the event improved the respective results to 16 and 19 successful classifications the missed events generally had low signal to noise ratio and small to medium volumes we then processed nearly 14 years of continuous seismic data from the same two stations to detect previously unknown events after postprocessing we classified 30 new events as rockslides of which we could verify three through independent observation in particular the largest new event with estimated volume of 500 000 m3 was not generally known within the swiss landslide community highlighting the importance of regional seismic data analysis even in densely populated mountainous regions our method can be easily implemented as part of existing earthquake monitoring systems and with an average event detection rate of about two per month manual verification would not significantly increase operational workload

the dynamic behavior of shallow marine reservoirs insights from the pliocene of offshore north trinidad the pliocene reservoirs of the north coast marine area block ncma 1 comprise shallow marine shoreface to shelf sandstones up to 30 m 98 ft thick and interbedded shelfal mudstones organized into stacked upward coarsening parasequences ca 25 70 m thick production behavior is strongly conditioned by the interplay of subregional sand distribution and aquifer connectivity and intrafield reservoir architecture complexity commonly in the form of clinoforms the m2 parasequence is a well connected reservoir unit and forms part of a late highstand systems tract with a strongly progradational architecture large scale reservoir connectivity can be demonstrated by pressure communication in producing fields up to 10 km 6 mi apart the widespread nature of the sand also links the reservoir to a significant aquifer that provides pressure support during field depletion in contrast clinoforms that dominate the m2 reservoir architecture at a variety of scales reduce lateral connectivity wells situated in individual sand bodies show significant pressure interference during production whereas wells that straddle bounding clinoforms possible parasequence boundaries although in pressure communication show more subtle pressure interference in the chaconia field clinoforms that bound lobate sand bodies in the m2 reservoir have also apparently slowed the onset of water cut within the field by several years and therefore increased reserves recovery similarly in the m6 reservoir of the ixora field a significant bounding clinoform has partitioned the field through much of its production life but production data are now suggesting breakdown and late stage pressure support across the same clinoform the m6 parasequences form part of a lower quality early highstand systems tract and are more discontinuous than their m2 counterpart due to well developed bounding clinoforms as such they are not characterized by large active aquifers and do not benefit from such prominent long term pressure support the m4 reservoir is an isolated sand body complex that forms part of a high frequency lowstand complex it shows similar stratigraphic heterogeneity to that displayed in the m2 with variations in pressure decline exhibited within individual wells of the same reservoir unit its isolated geometry means it is not connected to a regional aquifer and is therefore undergoing volumetric decline with no water breakthrough

rock slope movements along the mount currie fault scarp southern coast mountains british columbia rock slope movements are reported from mount currie ridge near pemberton in the southern coast mountains of british columbia the site displays linear trenches antislope scarps and tension cracks typical of mountain ridges undergoing slow deformation however the most prominent linear scarp on the ridge has been previously interpreted as a fault scarp kinematic tests on rock discontinuities demonstrate the feasibility of both toppling and plane sliding at this site ground motion vectors based on a 4 year laser electronic distance measurement edm record of slope movements are generally compatible with the results of the kinematic tests these results cast doubt on a strictly seismic interpretation of the mount currie scarp

a probabilistic approach for landslide hazard analysis abstract we present a general framework for probabilistic landslide hazard analysis with respect to other quantitative hazard assessment approaches this probabilistic landslide hazard analysis has the advantage to provide hazard curves and maps and to be applicable to all typologies of landslides if necessary accounting for both their onset and transit probability the method quantifies for a given slope location the exceedance probability of being affected by a landslide with a specific local intensity within a reference time interval i e the hazard curve under the common assumption that landslides behave as a poisson process hazard maps are calculated reducing the hazard curve to single values by choosing a fixed probability of exceedance following standards or regulation requirements the method is based on the assessment of a landslide onset frequency a runout frequency for long runout landslides and the local definition of landslide intensity which can be expressed through different parameters according to landslide typology for long runout landslides the runout and spatially varying intensity and uncertainty are considered hazard curves and maps play a fundamental role in the design and dimensioning of mitigation structures in land planning and in the definition of risk and hazard management policies starting from the general framework we apply the methodology for rockfall hazard analysis and we test it in an area affected by the christchurch 2011 earthquake new zealand which triggered a large number of rockfalls killing five people

factors controlling landslide frequency area distributions a power law relation for the frequency area distribution fad of medium and large landslides e g tens to millions of square meters has been observed by numerous authors but the fad of small landslides diverges from the power law distribution with a rollover point below which frequencies decrease for smaller landslides some studies conclude that this divergence is an artifact of unmapped small landslides due to lack of spatial or temporal resolution others posit that it is caused by the change in the underlying failure process an explanation for this dilemma is essential both to evaluate the factors controlling fads of landslides and power law scaling which is a crucial factor regarding both landscape evolution and landslide hazard assessment this study examines the fads of 45 earthquake induced landslide inventories from around the world in the context of the proposed explanations we show that each inventory probably involves some combination of the proposed explanations though not all explanations contribute to each case we propose an alternative explanation to understand the reason for the divergence from a power law we suggest that the geometry of a landslide at the time of mapping reflects not just one single movement but many including the propagation of numerous smaller landslides before and after the main failure because only the resulting combination of these landslides can be observed due to a lack of temporal resolution many smaller landslides are not taken into account in the inventory this reveals that the divergence from the power law is not necessarily attributed to the incompleteness of an inventory this conceptual model will need to be validated by ongoing observation and analysis also we show that because of the subjectivity of mapping procedures the total number of landslides and total landslide areas in inventories differ significantly and therefore the shapes of fads also differ considerably

distribution and causes of landslides in the eastern peloritani of ne sicily and western aspromonte of sw calabria italy abstract the peloritani and aspromonte areas are tectonically active mountainous regions of ne sicily and sw calabria respectively where landslides are the most common hillslope mass wasting process this study aims to elucidate the primary controls on the distribution and size of landslides in these two different landscapes these regions either side of the messina strait have similar lithologies but show different morphological characteristics in response to varied neo tectonic activity and climate landslides were identified utilising aerial photographs and landsat images frequency area statistics were calculated to determine the length scale of the most frequent interpretable landslides and compare our results with previous studies the frequency area power law exponents 1 99 in peloritani and 1 94 in aspromonte fall within the range of values that have been observed 2 0 0 5 in similar landscapes the peloritani ridge sicily has range parallel normal fault segments with the majority of landslides occurring in their footwalls there seems to be a strong coupling between tectonic activity and landslides where slope instability is exacerbated by faulting fracturing or jointing in otherwise low permeability gneiss and granite bedrock conversely in aspromonte calabria landslides are restricted to steep valley walls and are absent from interfluves this is because landslides are controlled by fluvial incision processes these observations confirm a relationship between the spatial distribution of landslides and the processes controlling slope failures

power law correlations of landslide areas in central italy abstract we have studied the frequency area statistics of landslides in central italy we consider two data sets data set a contains 16 809 landslide areas in the umbria marche area of central italy they represent a reconnaissance inventory of very old old and recent modern landslides the noncumulative frequency area distribution of these landslides correlates well with a power law relation exponent 2 5 over the range 0 03 km 2 a l 2 data set b contains 4233 landslides that were triggered by a sudden change in temperature on 1 january 1997 resulting in extensive melting of snow cover an inventory of these snow melt triggered landslides was obtained from aerial photographs taken 3 months after the event these landslides also correlate well with a power law relation with exponent 2 5 over the range 0 001 km 2 a l 2 we show that the correlation of data set b is essentially identical to the correlation of 11 000 landslides triggered by the 17 january 1994 northridge california earthquake we attribute a rollover for small landslides in data set a to incompleteness of the record due to erosion and other processes and to limitations in the reconnaissance mapping technique used to complete the inventory on the other hand we conclude that rollovers for small landslides in data set b and the california earthquake data are real and are associated with the surface morphology we conclude that the power law distribution is valid over a wide range of landslide areas and discuss possible reasons we also discuss the contribution of the snow melt and earthquake triggered landslide events to the total landslide inventory

identifying mechanisms of shore platform erosion using structure from motion sfm photogrammetry shore platforms control wave energy transformation which in turn controls energy delivery to the cliff toe and nearshore sediment transport insight into shore platform erosion rates has conventionally been constrained at mm scales using micro erosion metres and at m scales using cartographic data on apparently slowly eroding coasts such approaches are fundamentally reliant upon long term observation to capture emergent erosion patterns where in practise timescales are short and where change is either below the resolution or saturates the mode of measurement the collection of data that enables the identification of the actual mechanisms of erosion is hindered we developed a method to monitor shore platform erosion at millimetre resolution within metre scale monitoring plots using structure from motion photogrammetry we conducted monthly surveys at 15 0 25 m2 sites distributed across the hartle loup platform in north yorkshire uk over one year we derived topographic data at 0 001 m resolution retaining a vertical precision of change detection of 0 001 m we captured a mean erosion rate of 0 528 mm yr 1 but this varied considerably both across the platform and through the year we characterised the volume and shape of eroded material the detachment volume frequency and shape distributions suggest that erosion happens primarily via removal of shale platelets we identify that the at a point erosion rate can be predicted by the distance from the cliff and the tidal level whereby erosion rates are higher closer to the cliff and at locations of higher tidal duration the size of individual detachments is controlled by local micro topography and rock structure whereby larger detachments are observed on more rough sections of the platform faster erosion rates and larger detachments occur in summer months rather than in more energetic winter conditions these results have the potential to form the basis of improved models of how platforms erode over both short and long timescales

from geotechnical analysis to quantification and modelling using lidar data a study on rockfall in the reintal catchment bavarian alps germany in the year 2007 enhanced rockfall activity was observed within the scarp of a 500 bp rockslide in the reintal catchment northern calcareous alps germany the largest of a series of events took place in august when almost 50000 m of rock were detached from the subvertical rock face and deposited on a talus cone in this case study we focus on three aspects of rockfall research first we compile detailed geomorphological and geotechnical findings to explain the causes of the recent events the results of laboratory tests and stability estimations suggest that rockfall activity will persist in the future as the old rockslide scarp still contains unstable rock masses second we use digital elevation data from a pre event airborne lidar survey als and post event terrestrial laserscanning tls to quantify landform changes and the mass balance of the rockfall event s the widespread availability of als elevation data provides a good opportunity to quantify fresh events using a comparatively inexpensive tls survey this approach is complicated by uncertainties resulting from the difficult coregistration of als and tls data and the specific geometric problems in steep als and flat tls terrain it is therefore limited to at least medium sized events third the event s is simulated using the results of the lidar surveys and a modified gis based rockfall model in order to test its capability of predicting the extent and the spatial distribution of deposition on the talus cone results show that the model generally reproduces the process domain and the spatial distribution of topographic changes but frequently under and over estimates deposition heights copyright 2011 john wiley sons ltd

magnitude and frequency of rock falls and rock slides along the main transportation corridors of southwestern british columbia the two main transportation corridors of southwestern british columbia are subject to a range of rock slope movements rock falls rock slides and rock avalanches that pose significant risks to r

landslide blockage length estimation for the man made linear structures the landslide blockage length along a man made linear structure the alishan railway is analyzed herein the alishan railway runs from chiayi city to the alishan scenic area numerous landslide and debris flow disasters have blocked the railway since it began operations in 1911 in this study features of landslides are interpreted from spot 5 images along the alishan railway the results show that larger landslides along the railway exhibit a power law distribution in frequency area analysis the railway blockage length by landslide and its frequency can be linearized by plotting it in a log scale for a blockage length over 0 02 km the characteristics may be attributed to the fact that the landslide magnitude for its area and volume versus frequency exhibits a power law distribution it may thus be possible to estimate the blockage length of linear structures e g railway and expressway by landslides using the power law distribution

spatial and temporal rockfall activity in a forest stand in the swiss prealps a dendrogeomorphological case study abstract rockfall is a major threat to settlements and transportation routes in large parts of the alps while protective forest stands in many locations undoubtedly reduce rockfall risk little is known about the exact frequency and spatial distribution of rockfall activity in a given place or about how these parameters can be assessed therefore the objective of the present study was to reconstruct rockfall events with dendrogeomorphological methods and to analyse the spatial and temporal rockfall activity in a subalpine forest stand the study site is located in the transit zone of frequently passing rather small rockfall fragments mean diameter of 10 to 20 cm in all 33 stem discs from previously felled picea abies trees found at the foot of schwarzenberg in diemtigtal swiss prealps were sampled and a total number of 301 rockfall events were dated to between a d 1724 and 2002 results showed that the spatial distribution of rockfall changed slightly with time and that rockfall activity increased considerably over the last century in contrast rockfall magnitude presumably remained on a comparable level the seasonal occurrence of rockfall showed a clear peak during the dormant season of trees most probably in early spring furthermore on a 10 year moving average basis rockfall rates were positively correlated with mean annual as well as summer and winter temperatures this means that higher temperatures resulted in increased rockfall activity on the other hand no correlation with annual or seasonal precipitation totals was revealed overall this study provides an appropriate method for the detailed assessment of spatial and temporal variations in rockfall activity in a given place