influence of man made cuts on the stability of pyroclastic covers campania southern italy a numerical modelling approach intense rainfall in may 1998 and december 1999 caused disastrous landslides in the sarno quindici and cervinara areas campania southern italy the landslides began with slips of the local pyroclastic covers mantling the carbonate relief and then evolved into debris flows avalanches the study discussed in this paper used a numerical modelling approach to assess the influence of man made cuts on the stability conditions of pyroclastic covers the model that was developed took into account initial failure conditions in order to better simulate the impact of man made cuts along the slopes with or without water seepage into the permeable pumiceous layers of the pyroclastic multilayer numerical analysis of stress strain field clearly showed that tracks or geomorphological discontinuities had a negative impact on the multilayer stability conditions consequently preservation of this vulnerable environment requires correct forest management practices

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

spatial modelling and uncertainty assessment of pyroclastic cover thickness in the sorrento peninsula assessing spatial variability of soil thickness is a critical issue for understanding and predicting slope processes the present work was aimed at estimating the spatial scales at which the variation of pyroclastic cover thickness occurs in a sample area in the sorrento peninsula italy stochastic simulation was used to understand the spatial variability of pyroclastic cover thickness on mount pendolo and to assess its spatial uncertainty in the study area covering about 0 7 km2 thickness measurements were collected using electrical resistivity tomography profiles continuous core drillings and steel rod penetrometric tests variographic analysis revealed the occurrence of an anisotropic behaviour along the n50 and n140 directions in the latter anisotropic direction a nested variogram was fitted including 1 a long range component which could be related to large scale factors like the curvature of the slope and contributing area and 2 a shorter scale variation which is probably associated with the occurrence of denudation processes or to the articulate cover bedrock interface to assess the spatial variability and uncertainty of pyroclastic cover thickness a stochastic simulation algorithm was used and 500 equally probable images of cover thickness were yielded the results showed that a better thickness distribution map can be drawn by simulating the data collected on the slope and at the footslope separately the approach also allowed delineating the areas characterized by greater uncertainty suggesting supplementary measurements to further improve the cover thickness distribution model thus reducing the uncertainty

dynamic analysis of the 2012 johnsons landing landslide at kootenay lake british columbia the importance of undrained flow potential the johnsons landing landslide occurred on 12 july 2012 on the shores of kootenay lake british columbia the landslide consisted of poorly sorted low plasticity debris that initially descended a

frequency ratio model based landslide susceptibility mapping in lower mae chaem watershed northern thailand the purpose of this study is to produce a landslide susceptibility map for the lower mae chaem watershed northern thailand using a geographic information system gis and remotely sensed images for this purpose past landslide locations were identified from satellite images and aerial photographs accompanied by the field surveys to create a landslide inventory map ten landslide inducing factors were used in the susceptibility analysis elevation slope angle slope aspect lithology distance from lineament distance from drainage precipitation soil texture land use land cover lulc and ndvi the first eight factors were prepared from their associated database while lulc and ndvi maps were generated from landsat 5 tm images landslide susceptibility was analyzed and mapped using the frequency ratio fr model that determines the level of correlation between locations of past landslides and the chosen factors and describes it in terms of frequency ratio index finally the output map was validated using the area under the curve auc method where the success rate of 80 06 and the prediction rate of 84 82 were achieved the obtained map can be used to reduce landslide hazard and assist with proper planning of lulc in the future

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

the january 10 1997 pozzano landslide sorrento peninsula italy abstract from 1997 to 1999 a huge number of slides often turning into extremely rapid debris earth flows repeatedly affected the late quaternary volcaniclastic deposits mantling the carbonate slopes of campania region italy the sorrento peninsula was the epicentral district of the 1997 regional slope instability crisis some hundred shallow mass movements took place during january 1997 in this area these were the last episode of a long series of slope failure events dating back to mid 18th century results from geological and geomorphologic surveys are presented landslide mechanism and triggering factors are analysed for the most important mass movement which occurred during the january 9 11 1997 regional event on january 10 1997 at about 8 15 pm a rainfall induced debris slide debris flow occurred at pozzano province of naples mainly affecting the 79 ad pyroclastic products following a j path the landslide destroyed a private house and invaded the state road no 145 this event resulted in four deaths 22 persons injured and road closure for about 2 months there was less than 200 mm of rainfall in the 72 h period prior to the landslide although intense precipitation had occurred during a preceding 4 month period however the slope failure event was not preceded by an extreme short term antecedent rainfall as already noticed in previous landslides of this type in campania finally following a preliminary geotechnical characterization of volcaniclastic soils a slope stability back analysis was carried out which adopted the classical infinite slope scheme this analysis gave further evidence of the role played by pore pressure in reducing the overall shear strength of pyroclastic soils

numerical simulation of debris flows a key requirement in the assessment of landslide risk in such densely populated urban areas as hong kong consists of the prediction of potential runout distance or the extent of the subsequent debris flow this paper presents a three dimensional dynamic model of unsteady gravity driven debris flow the lagrangian galerkin finite element method is used to determine the nodal velocity and depth of soil column elements within the sliding mass with the momentum and mass conservation mathematically closed within the soil column elements the numerical solution also features a lumped mass matrix and a volume weighted procedure the method of least squares approximation plays a smoothing role which enhances stability and efficiency of the numerical solution scheme the nodal elevation during sliding is obtained via a dynamic bilinear interpolation of the elevation function for the base of the sliding mass furthermore the accuracy robustness and generality of this method are validated by experimental results

comparison of two depth averaged numerical models for debris flow runout estimation this paper analyses an important aspect of the continuum numerical modelling of rapid landslides as debris flows by using the same rheological parameter values are the results obtained with code

rainfall induced debris flows in pyroclastic deposits campania southern italy abstract a combination of empirical and physically based hydrological models has been used to analyze historical data on rainfall and debris flow occurrence in western campania to examine the correlation between rainfall and debris flow events rainfall data from major storms recorded in recent decades in western campania were compiled including daily series from several rain gauges located inside landslide areas supplemented by hourly rainfall data from some of the principal storms a two phase approach is proposed during phase 1 soil moisture levels have been modelled as the hydrological balance between precipitation and evapotranspiration on a daily scale using the method of thornthwaite geograph rev 38 1948 55 phase 2 is related to the accumulation of surplus moisture from intense rainfall leading to the development of positive pore pressures these interactions take place on an hourly time scale by the leaky barrel lb model described by wilson and wiezoreck env eng geoscience 1 1995 11 in combination with hourly rainfall records the lb model has been used to compare hydrological effects of different storms the critical level of retained rain water has been fixed by the timing of debris flow activity related to recorded storm events new rainfall intensity duration thresholds for debris flow initiation in western campania are proposed these thresholds are related to individual rain gauge and assume a previously satisfied field capacity condition the new thresholds are somewhat higher than those plotted by previous authors but are thought to be more accurate and thus need less conservatism

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

quantifying the three dimensional effects of anisotropic soil horizons on hillslope hydrology and stability abstract rainfall induced shallow landslides cause significant damage involving loss of life and property many hydrological processes such as rainfall infiltration soil water dynamics and slope stability are controlled by unsaturated soil properties such as unsaturated hydraulic conductivity natural soils often exhibit a certain degree of anisotropy in hydraulic conductivity due to stratification and compaction mechanisms in soil formation processes in this paper we investigate the effect of soil hydraulic conductivity anisotropy shca on hillslope hydrology and stability using a three dimensional hydrological model coupled with a probabilistic infinite slope stability model the model is applied in two independent case studies the first aims to quantify the combined effect of different anisotropy ratios lateral normal saturated hydraulic conductivity and hillslope morphologies convex concave and planar on slope stability anisotropy ratios are assumed in this case higher than one 1 2 10 results show that increasing the anisotropy ratio from 1 to 10 anticipates the failure time from 12 to 9 h after the start of rainfall and that in concave morphologies the unstable area tends to be wider than planar and convex the second application aims to simulate the soil moisture dynamic and the probability of failure at different depths 100 500 and 900 mm of a stratified volcanic soil making leverage on the model flexibility to accommodate shca no assumptions are made on the anisotropy ratio in this case study our results based on model parameter calibration and verification against in situ soil moisture measurements during the year 2009 showed good model performance in simulating the soil moisture dynamic kling gupta efficiency higher than 0 78 and confirmed no failure for the simulated year the promising results support the aspiration that the physically based hydrological model can complement and improve the current predictions of landslide early warning systems

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

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

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

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

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

an inverse conglomerate paleomagnetic test and timing of in situ terra rossa formation at bloomington indiana directions of remanent magnetism in an 2 m interval of terra rossa claystone at bloomington indiana cluster around the current earth magnetic field direction a fact consistent with authigenic formation of the terra rossa over the last 0 78 m yr the date of the latest earth s magnetic field reversal and suggesting a minimum terra rossa formation rate of 2 5m m yr paleomagnetic directions in limestone floaters within the terra rossa are indistinguishable from directions of the bedrock mississippian harrodsburg limestone indicating that the floaters are in situ and perfectly preserve their original stratigraphic position thus the red claystone containing the floaters is interpreted as an authigenic isovolumetric replacement of the harrodsburg the replacement of which the floaters escaped and precludes the possibility that the floaters and the surrounding claystone are a mudflow that had carried limestone blocks in it the implication that the claystone is authigenic independently confirms the petrographic observations reported previously that the red clay grew in situ replacing the underlying limestone at a moving metasomatic front rock magnetic studies of the terra rossa clays show evidence of both goethite and maghemite as main magnetic carriers of this remanence both minerals are independently known to occur in pisolites of the terra rossa the ferric ironbearing red clays also are weakly magnetic

influence of grass roots on shear strength of pyroclastic soils this paper investigates the effects of indigenous vegetation on the shear strength of loose pyroclastic soils of the campania region southern italy these soils are frequently affected by shallow

velocity and runout simulation of destructive debris flows and debris avalanches in pyroclastic deposits campania region italy the campanian apennines are characterized by the presence of monocline ridges mainly formed by limestone during the periods of volcanic activity of the somma vesuvius and phlegrean fields the ridges were mantled with pyroclastic materials in varying thickness the pyroclastics have been involved in destructive landslides both in historical time and in the recent past 1997 1998 1999 the landslides occur following intense and prolonged rainfalls in some cases landslides extended up to 4 km into the surrounding lowlands and reached towns causing severe destruction and over 200 deaths generally the landslides begin as small debris slides that develop into large shallow debris avalanches or debris flows involving pyroclastic horizons and colluvial soils 0 5 2 m thick on steep and vegetated slopes often at the heads of gullies during motion the landslide materials eroded vegetation and soils from the slope so that the moving material volume tended to increase then proceeding towards and beyond the base of the slopes the phenomena evolved into hyperconcentrated streamflow due to dilution by incorporating water the results of motion analyses are described an empirical rheological relationship was used including two principal terms that depend on the total normal stress and on the flow velocity on this basis the model has simulated the velocity and duration of debris avalanches and the distribution of the deposits the selected areas were those of sarno quindici and cervinara where a large amount of data is available both on the material properties and geomorphological setting it was found that the majority of the cases at the two sites can be simulated successfully with only one specific pair of rheologic parameters this provides the possibility for first order predictions to be made of the motion of future landslides such predictions will be a valuable tool for outlining potential hazard areas and designing remedial measures

some aspects of the initiation of debris avalanches in the campania region the role of morphological slope discontinuities and the development of failure abstract in may 1998 a prolonged period of rainfall caused disastrous landslides in the sarno quindici area campania southern italy the landslides initiated as small debris slides and developed into debris avalanches and debris flows involving the shallow pyroclastic deposits that lie on the steep vegetated slopes of this area in view of the potential for such events to occur again in this area an understanding of the initial failure mechanism is crucial if assessments are to be made of the hazard levels in this paper the results of detailed surveys of the morphological characteristics of the source areas are presented statistical analyses and parametrical relationships have been performed on key parameters demonstrating that the initial failures were associated with the presence of morphological discontinuities such as limestone scarps and road cuts notably the presence of man made cuts appears to have been responsible for about the 60 of the initial debris slides morphometric analysis has shown that the debris avalanches are characterised by a typical triangular shape statistical analyses have been used to try to relate the apex angles to relevant geomorphological parameters allowing for differences in local morphology the findings show some significant correlation

debris flow velocities and superelevation in a curved laboratory channel the vortex equation is often used to estimate the front velocity of debris flows using the lateral slope of the flow surface through a channel bend of a given radius here we report on laboratory e

spatial and temporal occurrence of rainfall induced shallow landslides of flow type a case of sarno quindici italy article i nfo rainfall induced shallow landslides of flow type provide unstable masses which often travel long run out distances with high velocities thus posing a high societal risk when they affect large areas therefore analysis of their spatial and temporal occurrence is relevant to landslide hazard assessment as the first step of the risk analysis in order to address this issue this paper outlines a multidisciplinary procedure that is applied to the may 1998 sarno quindici landslides southern italy whose spatial and temporal occurrence is not satisfactorily addressed in current literature the spatial occurrence of the landslides is analysed using heuristic models for both the source and propagation areas the temporal occurrence of the landslides is firstly compiled and then related to the cumulated rainfall stratigraphy and hydraulic boundary conditions finally the spatial and temporal occurrence of the main landslide triggering mechanism is modelled over the whole affected area by analysing the groundwater regime and slope stability conditions the obtained results show that the spatial and temporal occurrence is strongly related to stratigraphy and hydraulic boundary conditions at both the slope and massif scales they also highlight a suitable procedure for assessing the spatial and temporal occurrence of complex landslides over large areas