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

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

geological hazards in loess terrain with particular reference to the loess regions of china abstract the considerable morphodynamic energy provided by the continuing tectonic evolution of asia is expressed in high erosional potentials and very high rates of sediment production that make this continent unequalled as a terrestrial source of primary silt many of these environments are hazardous threatening human occupation health and livelihood especially in regions of dense population such as the loess lands of north china dry loess can sustain nearly vertical slopes being perennially under saturated however when locally saturated it disaggregates instantaneously such hydrocompaction is a key process in many slope failures made worse by an underlying mountainous terrain of low porosity rocks gully erosion of loess may yield very high sediment concentrations 60 by weight characteristic vertical jointing in loess influences the hydrology enlarged joints develop into natural sub surface piping systems which on collapse produce a loess karst terrain collapsible loess up to 20 m thick is common on the western loess plateau foundation collapse and cracked walls are common many rapid events following periods of unusually heavy monsoonal rain slope failure is a major engineering problem in thick loess terrain flow slide and spread types being common the results are often devastating in both urban and rural areas an associated hazard is the damming of streams by landslides the human population increases the landslide risk in china notably through imprudent land use practices including careless water management a number of environmentally related endemic diseases arise from the geochemistry of loess and its groundwaters including fluorosis cretinism kaschin beck disease keshan disease and goitre the chinese desert margins also have a major atmospheric dust problem the effect of such dust upon human health in these extensive regions including many large cities has yet to be evaluated but pneumoconiosis is thought to affect several million people in north and west china

an empirical statistical model for debris flow travel distance an empirical model is presented for analysis of debris flows based on field observations of landslides from clear cuts in the queen charlotte islands british columbia given an initial failure volume changes in event magnitude arising from entrainment and deposition along the path of movement are used to establish the point at which the cumulative flow volume diminishes to zero and therefore the total travel distance hillslope morphology is used to assign three types of flow behaviour unconfined confined and transition flow flow behaviour and slope angle determine the occurrence of entrainment or deposition in the model for every reach of the event path volume change in a reach is calculated from regression analysis of the queen charlotte islands field observations predictor variables are reach length width of entrainment and or deposition and slope angle together with a bend angle function and the incoming flow volume key words slope stability debris flow travel distance runout ris

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

geological and geotechnical characteristics of some loess and loessic soils from china and britain a comparison abstract derbyshire e and mellors t w 1988 geological and geotechnical characteristics of some loess and loessic soils from china and britain a comparison eng geol 25 135 175 loess and loessic deposits cover some 630 000 km 2 of the surface of mainland china the loess plateau of shanxi shaanxi gansu and ningxia being the type region of this formation loess thickness generally exceeds 100 m over large areas of the loess plateau the maximum recorded thickness being 335 m in eastern gansu province near the city of lanzhou in britain loess and loessic deposits form part of a group of materials collectively known as brickearth they occur predominantly as sporadic accumulations in the southeast of england and rarely attain a thickness of more than four metres despite their geographical separation the deposits from china and britain have a remarkable similarity in some of their physical and geotechnical characteristics samples from both locations have been examined and tested in the laboratory and the results are presented the scope of the testing programme involved mineralogical analyses soil microfabric studies using a scanning electron microscope index testing including plasticity grading and density measurements and the investigation of the compressibility characteristics of the soils with particular reference to their susceptibility to collapse a soil structure model based on scanning electron microscope studies is presented and discussed in relation to the perceived mode of formation of the soils and their postdepositional history

the effects of rockfall volume on runout distance the main goal of this paper is to clarify the effects of rockfall volume on its fluidization for this purpose outdoor rockfall experiments were carried out to analyze runout distances and individual movements of rockfall blocks and numerical simulations were conducted for these experiments to learn more about the mechanism of rockfall fluidization the rockfall experiments were conducted using an artificial slope on which granite slabs were surfaced and overlaid with cubiformed granite blocks the size and number of blocks were varied in this series of experiments further numerical simulations were carried out in which the coordinates of individual rockfall blocks were traced in three dimensional space from rockfall initiation to final deposition it became clear from the experiments and simulations that the runout distance had a positive correlation with the rockfall volume number of rockfall blocks and the runout distance of the gravity center of deposited rockfall mass had a negative correlation with the rockfall volume to clarify the mechanism of these two phenomena the positions of individual blocks from initial arrangements to final depositions were traced in the experimental and numerical simulations this revealed that the relative positions of each block along the slope direction were not changed during rockfall movement the reason for the block sequence preservation was that front facing blocks in the initial cube arrangement accelerated and rear facing blocks decelerated along the slope by internal collision between blocks further as the rockfall volume increased the opportunities for impact among the rockfall blocks increased with the front facing blocks pushed farther whereas the gravity center of the deposited rockfall mass had an inclination to travel shorter distances as rockfall blocks increased according to the increase of kinetic energy dispersed by the collision of blocks

failure mechanisms in loess and the effects of moisture content changes on remoulded strength abstract investigations into the failure mechanisms of loess slopes in the loess region of north central china have shown that a majority of mass movements are associated with shallow slab slides predominantly moving under tension the effects of soil moisture content are of paramount importance when dry vertical slopes in loess may exceed 15 m in height but under conditions close to saturation the structural strength of loess rapidly decreases causing failure of the slopes mass failure of loess occurs as collapse due to hydroconsolidation and disintegration of the loess fabric as a result of liquefaction or fluidization and can be associated with progressive failure processes local destruction of the openwork fabric of the loess can lead to small plastic movements within the loess deposits this is as close as loess can come to creep

modelling the erosional susceptibility of landslide catchments in thick loess chinese variations on a theme by jan de ploey abstract in his 1990 paper catena 17 175 183 jan de ploey proposed a system whereby catchments are viewed as functional units in which geomorphic work results from the combined effects of water erosion and mass movements his measure of erosional susceptibility of catchments es introduced the gravitational potential in addition to the kinetic energy of the eroding agents this modelling of the erosional susceptibility of catchments in terms of energy was being used to explore time dependent variations of es when jan de ploey died also at this time he extended an invitation to the present authors to test and extend his model using our data base on the landslide dominated catchments in the thick loess country of north central china this paper presents a series of new equations expressing variations in es using a data base for over 200 landslides in the loess covered mountainous terrain relative relief up to 1500 m of the lanzhou region of eastern gansu province these equations express the loss of potential energy of the landslide mass in relation to the relative relief and the pressure energy input in the form of rainfall these indices of erosional susceptibility can be used to analyse the differences in response from one catchment to another and through time between the characteristics of vegetation cover including land use hydrology geomechanical behaviour and mechanisms of movement on slopes using certain assumptions on percentage area of catchments affected by mass movement and long term mean annual precipitation in the lanzhou region the es equation suggests an estimate for non clayey materials of about 10 4 m 2 s 2 which is a significantly higher susceptibility value than the mean worldwide value for non clayey materials obtained by de ploey

quaternary mammalian faunas of the pampean region abstract knowledge of the fossil mammals from the pampean region of argentina has greatly increased in recent years to analyze the patterns of change in regional climates and environments through the quaternary the fossil record of land mammals was used two principal factors affected mammalian diversity in the pampean region during the pleistocene glaciations and the climatic environmental and sea level changes associated with them and the large numbers of north american taxa that immigrated to south america from the pliocene the regional climatic conditions changed from being warm and wet to being colder drier and more seasonal during the pleistocene as a consequence of glacial cycles cold and dry conditions were interrupted by relatively short warmer and wetter periods several pulses of expansion and contraction of steppes and subtropical forests are recorded this change in habitat produced the provincialism that has characterized the mammal faunas from the pampean region finally the most notable characteristic of the quaternary mammal fauna of south america is the almost complete extinction of large mammals during the latest pleistocene earliest holocene the evidence presented here is most consistent with a model that explains megafaunal extinction through climatic fluctuations as it appears that only a few species of large mammals survived until the holocene nevertheless a human presence could have accelerated the process of extinction

morphometric analysis of relic landslides using detailed landslide distribution maps implications for forecasting travel distance of future landslides abstract this study analyzed the morphometry of relic landslides in four mountainous areas in japan using detailed landslide maps issued by the national research institute for earth science and disaster prevention of japan the mobility of 338 relic landslides was evaluated based on the h l ratio i e the equivalent coefficient of friction the h l ratio strongly correlates with the initial slope tan r r 2 0 78 0 88 the h l ratio and tan r of recent disaster causing landslides within the past few decades were also measured in each investigated area the data of recent landslides correspond to the 95 lower prediction limit of the tan r h l regression line for relic landslides this result implies that morphometric analysis of relic landslides around an unstable mass allows for forecasting of travel distance of the unstable mass

the role of material properties and landscape morphology on landslide size distributions abstract it has been observed that landslide size distribution shows power law scaling for large landslide areas with a roll over for landslides below a certain threshold which frequently coincides with the modal peak of the distribution the physical reasons leading to this distribution are not yet fully understood the analysis of non cumulative size distribution of two landslide inventories in the italian alps confirms the existence of a power law scaling with exponent of 2 56 0 02 and demonstrates that the roll over is not due to under sampling since it occurs at landslide sizes significantly larger than mapping resolution the control of topography on landslide size distribution is investigated by a topographic analysis using the virtual tiling method we observe a power law scaling of topography with a roll over for finer scales which is comparable with that of landslide size distribution the control of material properties on landslide size and geometry is examined through deterministic and probabilistic 2d limit equilibrium slope stability analyses incoherent materials favour shallow landslides with no limitation in size cohesive materials favour deep landslides and show a limitation for small sizes multilayered materials with depth dependent strength show a limitation for both small and large landslides the joint probability of 1 the probability that a slope with a given size and slope gradient is unstable i e failure probability from probabilistic stability analysis and 2 the probability that a slope with a given size and slope gradient exists topographic analysis allows to build synthetic size distributions which show both power law scaling and roll over for multilayered materials we obtain a scaling exponent of the power law of 2 58 0 02 we suggest that the power law scaling in landslide size distribution results in the study area from the constraint of topography and the presence of multilayered materials or depth dependent strength the roll over is an intrinsic characteristic of the size distribution due to the contribution of cohesion to slope stability

effects of forest harvesting on the occurrence of landslides and debris flows in steep terrain of central japan landslides and debris flows associated with forest harvesting can cause much destruction and the influence of the timing of harvesting on these mass wasting processes therefore needs to be assessed in order to protect aquatic ecosystems and develop improved strategies for disaster prevention we examined the effects of forest harvesting on the frequency of landslides and debris flows in the sanko catchment central japan using nine aerial photo periods covering 1964 to 2003 these photographs showed a mosaic of different forest ages attributable to the rotational management in this area since 1912 geology and slope gradient are rather uniformly distributed in the sanko catchment facilitating assessment of forest harvesting effects on mass wasting without complication of other factors trends of new landslides and debris flows correspond to changes in slope stability explained by root strength decay and recovery the direct impact of clearcutting on landslide occurrence was greatest in forest stands that were clearcut 1 to 10 yr earlier with progressively lesser impacts continuing up to 25 yr after harvesting sediment supply rate from landslides in forests clearcut 1 to 10 yr earlier was about 10 fold higher than in control sites total landslide volume in forest stands clearcut 0 to 25 yr earlier was 5 8 10 3 m 3 km 2 compared with 1 3 10 3 m 3 km 2 in clearcuts 25 yr indicating a fourfold increase compared with control sites during the period when harvesting affected slope stability because landslide scars continue to produce sediment after initial failure sediment supply from landslides continues for 45 yr in the sanko catchment to estimate the effect of forest harvesting and subsequent regeneration on the occurrence of mass wasting in other regions changes in root strength caused by decay and recovery of roots should be investigated for various species and environmental conditions copyright 2007 john wiley sons ltd

investigating landslide related cracks along the edge of two loess platforms in northwest china cracks are widely developed along the edge of loess platforms in northwest china field surveys reveal that these cracks can be grouped into shallow and deeply penetrating ones the former occur at a small distance from the platform edge normally penetrate into the top unsaturated loess with the penetration depth being controlled by the joints in loess the latter penetrate deeper into the saturated loess farther away from the platform edge these cracks control the inflow and drainage of irrigation water the shallow penetrating crack can fail as a slide or fall with a volume of up to hundreds of cubic meters the deeply penetrating crack can fail as a flow like landslide with a volume of thousands of cubic meters or more a full scale field test simulating irrigation on the platform surface was conducted the two types of crack can be interconnected so that the water applied in the test finally flowed into the deep crack and was discharged from the platform analysis of soil stress states and the results of field test show that the deeply penetrating cracks could have both positive as well as negative effects on slope stability on the one hand water can flow more freely in the cracks and the loess could be saturated and trigger a landslide on the other hand the water can drain more easily along the crack and slope stability could be enhanced as the groundwater level is suppressed copyright 2012 john wiley sons ltd

debris flow runout predictions based on the average channel slope acs prediction of the runout distance of a debris flow is an important element in the delineation of potentially hazardous areas on alluvial fans and for the siting of mitigation structures existing runout estimation methods rely on input parameters that are often difficult to estimate including volume velocity and frictional factors in order to provide a simple method for preliminary estimates of debris flow runout distances we developed a model that provides runout predictions based on the average channel slope acs model for non volcanic debris flows that emanate from confined channels and deposit on well defined alluvial fans this model was developed from 20 debris flow events in the western united states and british columbia based on a runout estimation method developed for snow avalanches this model predicts debris flow runout as an angle of reach from a fixed point in the drainage channel to the end of the runout zone the best fixed point was found to be the mid point elevation of the drainage channel measured from the apex of the alluvial fan to the top of the drainage basin predicted runout lengths were more consistent than those obtained from existing angle of reach estimation methods results of the model compared well with those of laboratory flume tests performed using the same range of channel slopes the robustness of this model was tested by applying it to three debris flow events not used in its development predicted runout ranged from 82 to 131 of the actual runout for these three events prediction interval multipliers were also developed so that the user may calculate predicted runout within specified confidence limits

controlling factors of loess landslides in western china based on detailed field data from recent geo hazards surveys in the loess plateau region of western china this study analyzes the key factors that control loess landslides the evolution phase of river valleys the geological structure of slopes and the geometry of slopes are all found to play a role in determining the occurrence distribution and other characteristics of loess landslides groundwater and vegetation also contribute to their formation a combination of human engineering activities and precipitation events are the principal triggering factors for the instability of loess slopes

influence of diagenesis on sedimentary delta n 15 in the arabian sea over the last 130 kyr abstract sedimentary 15n records are valuable archives of ocean history but they are often modified during early diagenesis here we quantify the effect of early diagenetic enrichment on sedimentary n isotope composition in order to obtain the pristine signal of reactive n assimilated in the euphotic zone this is possible by using paired data of 15n and amino acid composition of sediment samples which can be applied to estimate the degree of organic matter degradation we determined 15n and amino acid composition in coeval sediments from ocean drilling program odp hole 772 b in the central arabian sea and from hole 724 c situated on the oman margin in the western arabian sea coastal upwelling area the records span the last 130 kyr and include two glacial interglacial cycles these new data are used in conjunction with data available for surface sediments that cover a wide range of organic matter degradation states and with other cores from the northern and eastern arabian sea to explore spatial variations in the isotopic signal in order to reconstruct pristine n values we apply the relationship between organic matter degradation and 15n enrichment in surface sediments to correct the core records for early diagenetic enrichment reconstructed 15n values suggest a significant role of n2 fixation during glacial stages an evaluation of two preservation indices based on amino acid composition reactivity index ri jennerjahn and ittekkot 1997 and the degradation index di dauwe et al 1999 in both recent sediments and core samples suggests that the ri is more suitable than the di in correcting arabian sea 15n records for early diagenetic enrichment

gravity erosion on the steep loess slope behavior trigger and sensitivity abstract gravity erosion is a dominant geomorphic process on the widespread steep loess slopes yet it is not well understood due to the complexity of failure occurrence and behavior this study conducted a series of experiments in the laboratory to test the stability of different slope geometries and rainfalls and then performed a sensitivity analysis to quantitatively explore the triggering mechanisms of mass failure on the steep loess slope a topography meter designed by the authors was used to quantitatively measure the process of gravity erosion and the increase rate analysis method presented by the authors was also used to analyze the sensitivity of gravity erosion the following three types of gravity erosion were observed landslide avalanche and mudslide in an event of rainfall various types of gravity erosion might emerge in the same period and mass failures with the same mode and similar size often adjacently appeared sometimes a group of mass failures might happen on a large slowly slipping block then the increase rate analysis method was used to evaluate variations in the gravity erosion with respect to changes in other causal parameters of rainfall duration intensity and slope height gradient climate driven factors and topography triggers had prominent influences on gravity erosion whether for the total amount or the peak amount in an experiment the largest sensitivity parameter on both landslides and mudslides was that of rainfall duration in comparison topography was relatively less influential for the total amount in an experiment the sensitivity parameters of rainfall duration on the landslide and mudslide were 24 9 and 19 5 respectively while the sensitivity parameter of rainfall intensity on the avalanche was 2 2 for the peak amount in an experiment the sensitivity parameter of rainfall duration on the landslide and mudslide were 5 5 and 15 6 respectively meanwhile the sensitivity parameter of slope gradient on the avalanche was 4 6 the experimental results obtained here provide an insight into the pre failure mechanisms and processes of steep loess slopes

travel distance angle for rapid landslides in constructed and natural soil slopes rapid landslides in constructed and natural soil slopes have the potential to cause loss of life destruction of property and damage to the natural environment because the velocity of the slide

study of the 1920 haiyuan earthquake induced landslides in loess china many large scale landslides induced by earthquakes have been reported in loess soils they often cause catastrophes because they travel long distances at high velocity to clarify the mechanism of these landslides field survey was performed on the landslides triggered by the haiyuan earthquake china 1920 and a series of ring shear tests was conducted on the loess soils collected from a landslide the field surveys revealed that most of the loess landslides triggered by the haiyuan earthquake occurred on concave slopes gentler than 15 with long runout distance showing very small equivalent friction angle cyclic ring shear tests on saturated specimens in the undrained condition showed that when cyclic shear stress was applied to a loose loess specimen pore pressure was built up gradually before the failure and after that large pore pressure was quickly generated due to the failure of loess soil structure meanwhile to investigate the mechanism that produces the high mobility of loess landslides ring shear tests were conducted on loess specimens with large shear displacement of up to several meters under the undrained condition and it was found that the initial normal stress has no effects and overconsolidation ratio has little if any effects on the apparent friction angle in the steady state for loess soils results of tests on soils at different saturation degrees revealed that the reduction in shear strength results more likely from the generation of pore water pressure not of pore air pressure

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

landslide volumes and landslide mobilization rates in umbria central italy abstract a catalogue of 677 landslides of the slide type was selected from a global database of geometrical measurements of individual landslides including landslide area al and volume vl the measurements were used to establish an empirical relationship to link al in m2 to vl in m3 the relationship takes the form of a power law with a scaling exponent 1 450 covers eight orders of magnitude of al and twelve orders of magnitude of vl and is in general agreement with existing relationships published in the literature the reduced scatter of the experiential data around the dependency line and the fact that the considered landslides occurred in multiple physiographic and climatic environments and were caused by different triggers indicate that the relationship between vl and al is largely independent of the physiographical setting the new relationship was used to determine the volume of individual landslides of the slide type in the collazzone area central italy a 78 9 km2 area for which a multi temporal landslide inventory covering the 69 year period from 1937 to 2005 is available in the observation period the total volume of landslide material was vlt 4 78 107 m3 corresponding to an average rate of landslide mobilization l 8 8 mm yr 1 exploiting the temporal information in the landslide inventory the volume of material produced during different periods by new and reactivated landslides was singled out the wet period from 1937 to 1941 was recognized as an episode of accelerated landslide production during this 5 year period approximately 45 of the total landslide material inventoried in the collazzone area was produced corresponding to an average rate of landslide mobilization l 54 mm yr 1 six times higher than the long term rate the volume of landslide material in an event or period was used as a proxy for the magnitude of the event or period defined as the logarithm base 10 of the total landslide volume produced during the event or period with this respect the new relationship to link al and vl is a starting point for the adoption of a quantitative process based landslide magnitude scale for landslide events

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

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

topography and volume effects on travel distance of surface failure the authors investigated factors affecting the travel distance of a surface failure and developed a simple model for estimating the distance based on soil properties and topographic factor the authors conducted field surveys and various soil tests for a number of surface failures that occurred during torrential rain at the end of august 1998 in southern fukushima prefecture japan the authors studied the effects of various factors such as landslide volume pore water pressure slope inclination and the internal friction near the slip surfaces on the travel distances the analyses showed no clear relationship between landslide volume and equivalent coefficient of friction which was likely attributable to the very small range of volume compared to other studies on catastrophic landslides the effect of excess pore water pressure was likely negligible because undrained conditions were not to be maintained at the shallow flow depths a positive correlation was shown between slope inclination and equivalent coefficient of friction this correlation was attributable to two factors one was positive correlation between the internal friction on the slip surface and slope inclination and the other was the kinetic energy dissipation of moving mass that occurred at the inclination changing point between a slope and a sedimentary flat surface the authors then developed a predictive model for critical flow inclination of landslide by installing the factors of soil properties and slope inclination factors the model predicted equivalent coefficient of frictions which were very similar to the observed values thus verifying the effectiveness of the model

undrained shear behavior of loess saturated with different concentrations of sodium chloride solution abstract a series of ring shear tests was conducted on saturated loess to investigate the effects of nacl concentration in pore water and desalinization on the shear behavior under undrained conditions the loess samples were taken from the ground surface of a frequently active landslide in china were saturated by de aired distilled water with different concentrations of nacl and then were sheared undrained after that the samples were retrieved remolded re set into the shear box and re saturated by passing through de aired distilled water such that the samples were desalinized and then were sheared undrained again through comparing the undrained shear behavior the effects of nacl in the pore water and desalinization on the undrained shear behavior of loess were examined the results showed that the variation of nacl concentration in pore water can strongly affect the shear behavior of saturated loess both the peak shear strength and steady state strength increased with increase of nacl concentration until a certain value after which they decreased with further increase of nacl concentration meanwhile the peak shear strength and steady state strength of the desalinized samples recovered to those of the original sample hence the effects of salinization are reversible these findings may be of practical importance to better understand the repeated occurrence of some irrigation induced loess landslides in china

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

heavy rainfall triggered loess mudstone landslide and subsequent debris flow in tianshui china abstract continuous and heavy precipitation triggered a large loess landslide at the southern dagou village of mapaoquan town tianshui city gansu province of china on july 21 2013 the landslide debris rapidly turned into a debris flow that was deposited in the ravine mouth with the volume of 1 9 105 m3 detailed field mapping three dimensional laser scanning aerial photograph interpretation and laboratory tests were carried out to study the formation and moving characteristics of the landslide and subsequent debris flow the results showed that 1 the peak flow velocity and peak discharge of the debris flow were estimated to be approximately 7 2 m s and 730 m3 s respectively the velocity had a tendency to first increase and then decrease from the head to entrance in the dagou gully 2 the analysis of rainfall conditions showed that the effective antecedent rainfall within 7 days and hourly rainfall intensity which triggered the slide debris flows was 239 mm and 20 mm h respectively compared with the critical rainfall in this area the effective antecedent rainfall was found to be more significant in triggering this event 3 the mean and effective particle sizes were approximately 0 73 1 3 mm and 0 036 0 087 mm respectively and had the same distribution along the gully as the velocity which confirmed the process of the variation in the flow velocity 4 the scale amplification was very obvious in the formation and moving process of the slide debris flows