hydrological response of loess slopes with reference to widespread landslide events in the heifangtai terrace nw china abstract in the heifangtai terrace nw china flooding irrigation is common for the cropland production and has increased the groundwater table by 20 30 m over the past five decades it is believed that excessive irrigation has induced a large number of loess landslides in this area however these loess landslides responses to hydrological changes have still not been well understood therefore 43 boreholes and 51 2d electrical resistivity tomography ert profiles with a total length of 40 km have been investigated to analyze the hydrological characteristics for the whole terrace and characterize the effects of hydrological changes on the occurrence of different types of loess landslides our main findings are as follows 1 three groundwater domes are found in the center and eastern part of the heitai terrace and the groundwater table is gradually rising in the whole terrace based on the ert results 2 the rising rate of groundwater table at the center of the terrace is twice greater than that at the margin of the terrace and it takes approximately 4 months for irrigation water to penetrate from the top surface to the saturated layer 3 landslide deposits could block drainage channels of groundwater increase the localized hydraulic gradient and result in rising of local groundwater table at the edge of the terrace 4 the resultant hydraulic gradient impels the groundwater from the center to seep out on the eastern and southern margins and new landslides are prone to occur in the main scarp of landslides with rising groundwater table the type and magnitude of landslides are affected by groundwater seepage and movement in order to fundamentally control the occurrence of landslides effective drainage system and the restrained amount of irrigation water are needed

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

loessial soils of priangaria transbaikalia mongolia and northwestern china abstract comparative analysis of loessial soils from priangaria transbaikalia western mongolia and northwestern china investigated the differences in genesis microstructure plasticity and swelling and collapsibility priangarian loess like deposits formed through a combined model where during sedimentation individual primary layers of aeolian origin were deposited in a general background of deluvial deposits successive strata with differing aeolian additions were the media for soil formation microstructure is aggregated skeletal in all areas there is a similarity between the microstructure parameters and the structural model of the loessial soils of priangaria and northwestern china and between soils of transbaikalia and western mongolia the mineral composition particularly smectite and the coefficient of freedom of the fine clay fraction are the factors controlling swelling the loessial soils of transbaikalia western mongolia and northwestern china exhibit collapsibility in priangaria the manifestation of this property is different resulting from the climatic zonation and the differences in genesis

micromorphological investigations of the late quaternary loess paleosol sequences of the kashmir valley india abstract the loess paleosol sequences of the karewa group preserve a valuable repository of the late quaternary climatic changes and the landscape evolution history of the karewa basin of kashmir valley in their lithological and pedogenic records three representative loess paleosol sections at shankerpora sp khan sahib ks and pattan pt localities were chosen for detailed lithostratigraphic fieldwork and micromorphological observations of thin sections lithostratigraphic analysis revealed lateral and vertical variation in thickness and number of paleosol profiles from south west to north west of the karewa basin suggesting the availability of land surface for periodic loess deposition the sp section is marked by 6 sp s6 s7 s8 s9 s10 s12 ks section by 3 ks s2 s4 s5 and pt section by 2 pt s1 s3 thick mature paleosol profiles theses paleosols have well developed ah and btk horizons representing prolonged land surface stability when pedogenic processes outpace loess deposition on the other hand comparatively thin to thick paleosol profiles represent weak to moderate pedogenic maturity indicating short stratigraphic breaks with rapid loess deposition micromorphological observations of thin sections suggested that clay illuviation and caco3 accumulation have operated within the paleosol profiles caco3 features are often associated with clay coatings suggesting decalcification of carbonates followed by clay illuviation pedogenic caco3 probably resulted from the precipitation of the soil solution near the average depth of wetting front the pedogenic caco3 illuvial clay mottles iron manganese features pedal microstructure and blocky aggregates reveal variation in the pedogenic maturity among and within the loess paleosol sections the morphological both micro and macro morphological attributes of loess paleosols suggest variation of climatic conditions during the late quaternary period in the karewa basin of kashmir valley india

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

fault offsets and lateral crustal movement on europa evidence for a mobile ice shell abstract right lateral structural offsets of 25 km have been identified on the icy galilean satellite europa these occur along dark lineaments oriented orthogonally to wedge shaped bands which are also 25 km wide wedge shaped bands are interpreted as dilated tension fractures which formed as crustal blocks or plates 50 100 km across separated and slipped past each other along flanking strike slip faults this style of deformation does not appear to be characteristic of other lineament types and with the exception of earth appears to be unique to europa together the subparallel wedge shaped b bands form a broad nw se trending belt 1500 km long and less than 500 km across near the anti jovian point this belt is interpreted as a major crustal fracture or rift zone with a pole of rotation determined by the strike slip faults near 47 s 144 w and an approximate ne sw direction of maximum tensile stress extension may have been areally compensated at agenor linea a bright band of possible compressional origin global expansion tidal distortion and nonsynchronous rotation do not explain the inferred minimum principal i e least compressive stress directions alternatively fracturing near the anti jovian point may be a result of i solid state convection in the lower ice crust possibly triggered by uneven heat flow from the silicate interior ii rotation of the icy shell about the sub and anti jovian points induced by latitudinal lithospheric thickness variations or iii preferential strain accumulation from the rest of the icy shell no significant distortion of the crustal blocks occurred during fracturing and rotation indicating that the icy crust was probably mechanically decoupled from the silicate interior in this region over the time scale of fracturing decoupling on a global scale is also likely the simple geometry of lineaments argues for formation in an icy lithosphere not a silicate one and other evidence for fracturing caused by nonsynchronous rotation stress is not compatible with a tidally locked silicate interior which we show is likely unless the ice shell rotates independently decoupling could have been due to either warm ice or liquid water near the base of the icy crust mechanical bounds on lithospheric thickness a few to 10 km lead to heat flow estimates that admit both possibilities but favor decoupling by liquid water

a review of shear and tensile strengths of the malan loess in china abstract loess deposits cover about 640 000 km 2 of china equivalent to about 6 7 of the total area of the country the loess plateau alone covers approximately 317 000 km 2 making it the largest bulk accumulation of loess on the earth land instability hazards in the loess plateau are frequent and varied among which the cracking sliding beng hua in chinese failure is a typical mode cracking sliding failures commonly occur in the malan loess at volumes of the order of 100 m 3 and cause more than 100 deaths per year as the tension in the upper part of the failure plane and shearing sliding along the lower part mobilize cracking sliding failures this failure mode demands an investigation into the tensile and shear strengths this paper presents a review of these properties based on a large collection of literature both tensile and shear strengths of the malan loess decrease with water content and increase with dry density resulting in close multi regression correlations large differences between undisturbed and disturbed tensile strengths of the loess indicate the significance of its structure shear strength of the loess is direction dependent indicating strong anisotropy of the loess structure test method sample size and loading rate all influence the measured tensile strength

the mechanics of a saturated silty loess with a transitional mode problems of identifying unique normal compression and critical state lines have been found in gap graded soils and also some silty soils a mode of behaviour sometimes known as transitional loess is a typical silty soil that covers up to 631 000 km2 in china and is of great significance as a result of the large number of engineering projects under construction to examine the potential transitional behaviour in loess an extensive series of carefully controlled oedometer tests and triaxial tests on intact and reconstituted specimens were carried out loess specimens with a wide range of initial void ratios were reconstituted using different preparation methods intact specimens were taken from two depths but their natural variabilities were not significant and could be neglected apart from their difference in the initial void ratios the results have highlighted the features of transitional behaviour in this loess not only in reconstituted but also intact states and in particular that there is an i

loess is not just the accumulation of dust most regrettably there is much misuse of terminology in connection with the concept of loess and the interpretation of its origin people often speak and write incorrectly about loess accumulation even loess specialists who are aware of the fact that loess as a concept has to satisfy at least 10 criteria loess is not simply dust carried and deposited by wind dust only becomes loess after the passage of a certain amount of time in a given geographical zone i e only through diagenesis in certain ecological environments to state that loess is of aeolian origin is an oversimplification and an incorrect definition because an aeolian origin applies only to the dust from which the loess has been formed we are aware of the fact that airborne dust cannot be transformed into loess in every geographical environment but only under those conditions typical of semi arid grassland or steppe or forested steppe the process primarily occurs where the rate of dust accumulation exceeds sheet wash or weathering soil formation rates if the rate of dust accumulation is less than that of surface erosion or of soil biogenetic processes the dust then develops into soil or through intensive weathering and increased precipitation into loam or clay only part of the aeolian dust transported and deposited in a zone suitable for loess formation remains there permanently and is transformed in situ into loess dust not affected by diagenesis is usually further transported by snowmelt or rainwash and is only transformed into loess after it has been redeposited the loess itself however is easily erodible and its minerals are readily reworked and reaccumulated and given the appropriate conditions it readily undergoes diagenesis again we do not always have sufficient evidence to determine whether a given loess body is of primary or secondary origin traditionally the minerals making up primary loess have been regarded as originating in dust accumulated by aeolian processes secondary loess by contrast is different from typical loess in many ways and it is not unusual to find various loess series in which superimposed dust fractions have been transformed into loess by different processes recently we have observed that the origin of various types of loess is governed by differences in litho ecological conditions rather than by the way in which the mineral material from which the loess is derived dust has been primarily accumulated loessification is therefore determined by environmental conditions

digital photogrammetric analysis and electrical resistivity tomography for investigating the picerno landslide basilicata region southern italy abstract digital photogrammetric analysis and electrical resistivity tomography ert techniques were applied to evaluate the volume of material involved in a complex roto translational slide occurred in the territory of picerno basilicata region southern italy analytical and digital photogrammetric techniques facilitated a multi temporal analysis of aerial photos for the years 1997 2004 and 2006 in order to identify different geomorphologic features scarps terraces and trenches of the landslide and their development the analytical and digital photo interpretation was performed at the maximum scale of 1 5000 geological and geomorphological surveys were carried out to verify photo interpretation results digital elevation models dems for 1997 2004 and 2006 were produced by applying the grid adaptive method the differential dems 2006 1997 2006 2004 2004 1997 for the most dangerous part of the landslide allowed us to recognize the areas affected either by deposition or erosion and also estimate any altitudinal changes in each geomorphologic unit to detect the sliding surface and estimate the thickness of the sliding material several transversal and longitudinal ert profiles were obtained the electrical images of subsurface supported by stratigraphical data from boreholes were integrated with the information from the dems the altitudinal changes and the sizes of the source and accumulation areas allowed us to estimate the volume of material involved in the mass movement the fusion of data from different sensors allows us to gather indications on the surface and subsurface characteristics of the landslide providing useful information for landslide mitigation activities such an approach can help both to improve our knowledge and overcome the drawbacks of each methodology

landform characterization using geophysics recent advances applications and emerging tools abstract this paper presents an overview of the strengths and limitations of existing and emerging geophysical tools for landform studies the objectives are to discuss recent technical developments and to provide a review of relevant recent literature with a focus on propagating field methods with terrestrial applications for various methods in this category including ground penetrating radar gpr electrical resistivity er seismics and electromagnetic em induction the technical backgrounds are introduced followed by section on novel developments relevant to landform characterization for several decades gpr has been popular for characterization of the shallow subsurface and in particular sedimentary systems novel developments in gpr include the use of multi offset systems to improve signal to noise ratios and data collection efficiency amongst others and the increased use of 3d data multi electrode er systems have become popular in recent years as they allow for relatively fast and detailed mapping novel developments include time lapse monitoring of dynamic processes as well as the use of capacitively coupled systems for fast non invasive surveys em induction methods are especially popular for fast mapping of spatial variation but can also be used to obtain information on the vertical variation in subsurface electrical conductivity in recent years several examples of the use of plane wave em for characterization of landforms have been published seismic methods for landform characterization include seismic reflection and refraction techniques and the use of surface waves a recent development is the use of passive sensing approaches the use of multiple geophysical methods which can benefit from the sensitivity to different subsurface parameters is becoming more common strategies for coupled and joint inversion of complementary datasets will once more widely available benefit the geophysical study of landforms three cases studies are presented on the use of electrical and gpr methods for characterization of landforms in the range of meters to 100 s of meters in dimension in a study of polygonal patterned ground in the saginaw lowlands michigan usa electrical resistivity tomography was used to characterize differences in subsurface texture and water content associated with polygon swale topography also a sand filled thermokarst feature was identified using electrical resistivity data the second example is on the use of constant spread traversing cst for characterization of large scale glaciotectonic deformation in the ludington ridge michigan multiple cst surveys parallel to an 60 m high cliff where broad 100 m synclines and narrow clay rich anticlines are visible illustrated that at least one of the narrow structures extended inland a third case study discusses internal structures of an eolian dune on a coastal spit in new zealand both 35 and 200 mhz gpr data which clearly identified a paleosol and internal sedimentary structures of the dune were used to improve understanding of the development of the dune which may shed light on paleo wind directions

characterizing hydrological processes on loess slopes using electrical resistivity tomography a case study of the heifangtai terrace northwest china abstract from the perspective of engineering geology loess has long been considered as a homogeneous and porous material it is commonly believed that water penetrates loess via pores and in some cases causing mass movements however several researchers have expressed doubts about this mechanism as a cause of slope failures in loess and moreover the actual hydrological processes operating in loess deposits and their effect on slope failures have not been fully investigated here we present the results of an electrical resistivity survey of the heifangtai loess terrace in northwestern china designed to characterize the hydrological processes in loess slopes and their relationship with slope failures the heifangtai loess terrace is located on the fourth terrace of the yellow river and consists of 57 m thickness of aeolian loess 2d and 3d electrical resistivity tomography ert was used to monitor the movement of ground water before and after irrigation and rainfall events and the evolution of a sink hole in the toe of the landslide deposits our main findings are as follows 1 based on the 2d ert results the depth of infiltration into the thick unsaturated loess is not more than 5 m in the profile at the top of the landslide 2 electrical resistivity decreased as a result of water infiltration through sinkholes and this process can increase the soil water content and induce soil liquefaction which can eventually result in land sliding 3 landslide deposits block the groundwater drainage channels through the loess which results in the concentration of water in the toe of the landslide consequently groundwater together with rainfall triggers the failure of sinkholes or cracks which may induce a continuing process of new slope failures at the sites of past landslide

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

rapid least squares inversion of apparent resistivity pseudosections by a quasi newton method1 a fast inversion technique for the interpretation of data from resistivity tomography surveys has been developed for operation on a microcomputer this technique is based on the smoothness constrained least squares method and it produces a two dimensional subsurface model from the apparent resistivity pseudosection in the first iteration a homogeneous earth model is used as the starting model for which the apparent resistivity partial derivative values can be calculated analytically for subsequent iterations a quasi newton method is used to estimate the partial derivatives which reduces the computer time and memory space required by about eight and twelve times respectively compared to the conventional least squares method tests with a variety of computer models and data from field surveys show that this technique is insensitive to random noise and converges rapidly this technique takes about one minute to invert a single data set on an 80486dx microcomputer

recognition of large scale deep seated landslides in forest areas of taiwan using high resolution topography abstract large deep seated landslides can be reactivated during intense events and they can evolve into destructive failures they are generally difficult to recognize in the field especially when they develop in densely forested areas a detailed and constantly updated inventory map of such phenomena and the recognition of their topographic signatures is absolutely a key tool for landslide risk mitigation the aim of this work is to test in forested areas the performance of the new automatic and objective methodology developed by tarolli et al 2012 for geomorphic features extraction landslide crowns from high resolution topography lidar derived digital terrain models dtms the methodology is based on the detection of landslides through the use of thresholds obtained by the statistical analysis of variability of landform curvature the study was conducted in a high risk area located in the central south taiwan where an accurate field survey on landsliding processes and a high quality set of airborne laser scanner elevation data are available the area has been chosen because some of the deep seated landslides are located near human infrastructures and their reactivation is highly dangerous thanks to lidar s capability to detect the bare ground elevation data in forested areas it was possible to recognize in detail landslide features also in remote regions difficult to access the results if compared with the previous work of tarolli et al 2012 mainly focused on shallow landslides and in a not forested area indicate that for deep seated landslides where the crowns are more evident and they are present at large scale the tested methodology performs better higher quality index the method can be used to interactively assist the interpreter user on the task of deep seated landslide hazard mapping and risk assessment planning of such regions

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

factors controlling the spatial distribution of soil piping erosion on loess derived soils a case study from central belgium abstract collapsible loess derived soils are prone to soil piping erosion where enlargement of macropores may lead to a subsurface pipe network and eventually to soil collapse and gully development this study aims at understanding the main factors controlling spatial patterns of piping in loess derived soils under a temperate climate to map the spatial distribution of piping and identify the environmental controls on its distribution a regional survey was carried out in a 236 km2 study area in the flemish ardennes belgium orthophotos taken at optimal field conditions winter were analyzed to detect piping in open landscapes and ground thruthing was systematically done through field surveys in total 137 parcels having 560 collapsed pipes were mapped dimensions of the sinkholes and local slope gradient were measured in the field and topographical variables were derived from lidar data land use plays an important role as 97 of the sites with piping are found under pasture the probability of piping increases rapidly on hillslopes with gradients exceeding 8 and with a concave profile and plan curvature enhancing subsurface flow concentration the zones with soil profiles on shallow loess over a relatively thin layer of homogeneous blue massive clays aalbeke member are most prone to piping soil characteristics are of less importance to explain piping occurrence furthermore the topographical threshold line indicating the critical slope gradient for a given contributing drainage area was determined this threshold line negative power relation is similar to the threshold line for shallow gully initiation

sedimentology and shale modeling of a sandstone rich fluvial reservoir upper statfjord formation statfjord field northern north sea sandstone rich fluvial reservoirs of the upper part of the statfjord formation in statfjord field northern north sea include significant proportions of interstratified shale beds which complicate the production of oil under a high pressure miscible gas flood flood plain mudstones characterized by pedogenic alteration and finely laminated abandoned channel facies form the most important flow barriers mudstones deposited in flood plains are expected to have a greater lateral continuity than those deposited in abandoned channels fluctuations in allogenic factors such as base level and sediment supply rates have led to a variable preservation of the mudstones this combination of different facies types and fluctuating allogenic control has led to a complex barrier dist ibution within the reservoir which is difficult to describe using conventional mapping techniques a procedure based on two stochastic simulation techniques has been adopted in order to model the complex barrier distribution a two dimensional markov field model is used as an alternative to conventional shale mapping to describe the distribution of shale beds that are correlated between two or more wells the model is based on probabilistic estimations of shale continuity between well pairs and allows the simulation of local channel incision through otherwise extensive shale beds a marked point process model is adopted to describe the distribution of smaller scale discontinuous barriers within the reservoir sand bodies it is based on probabilistic estimations of shale dimensions defined using cumulative frequency distributions the stochastic modeling procedure allows greater flexibility to include a variety of geological interpretations and assumptions in the heterogeneity model and the increased geological input results in more realistic models of communication between and vertical permeability within the reservoir sand bodies

influence of lixiviation by irrigation water on residual shear strength of weathered red mudstone in northwest china implication for its role in landslides reactivation abstract irrigation in loess tableland areas of northwest china has induced a large number of landslides around their edges of which loess red mudstone landslide is one of the most frequent types salt sinters commonly observed at the toes of these landslides where the weathered red mudstone wrm outcrops have raised the possibility that removal of soluble salts in the wrm by irrigation water could be crucial in the reduction of its shear strength and thus in the occurrence of these landslides in order to investigate the effects of lixiviation by irrigation water on residual shear strength of the wrm samples of the wrm close to two landslides in lanzhou city one of the largest cities in northwest china were tested after being treated under different conditions these included 1 saturation with the yellow river water the only source of irrigation 2 saturation with groundwater and 3 saturation and leaching with deionized water based on the results of these tests specific mechanisms of residual shear strength reduction of the wrm due to lixiviation by irrigation water were discussed in terms of physico chemical interactions between the wrm and water it was found that lixiviation reduced residual shear strength and residual friction angle r of the wrm by up to 65 and 62 respectively after being leached 6 times this coincided with a dramatic dissolution and leaching of soluble salts from the wrm particle size distribution showed that the more the wrm was leached the more the clay fraction and the lesser coarser fractions this suggested that reduction in residual shear strength of the wrm could be attributed to mainly disaggregation of particles coarser than clay and to a lesser degree to weakening of interparticle forces among individual clays it was further postulated that variation in clay mineralogy may influence performance of particle disaggregation

prediction of rainfall induced shallow landslides in the loess plateau yan an china using the trigrs model in this work a transient rainfall infiltration and grid based regional slope stability model trigrs was implemented in a case study of yan an city northwest china in this area widespread shallow landslides were triggered by the 12 july 2013 exceptional rainstorm event a high resolution dem soil parameters from in situ and laboratory measurements water table depths the maximum depth of precipitation infiltration and rain gauge corrected precipitation of the event were used as inputs in the trigrs model shallow landslides triggered on the same day were used to evaluate the modeling results the summarized results are as follows i the characteristics and distribution of thirty five shallow landslides triggered by the 12 july 2013 rainfall event were identified in the study area and all were classified as shallow landslides with the maximum depth area and volume less than 3 m 200 m2 and 1000 m3 respectively ii four intermediate factor of safety fs maps were generated using the trigrs model to represent the scenarios 6 12 18 and 24 hours after the storm event the area with fs 1 increased with the rainfall duration the percentage of the area with fs 1 was 0 2 3 3 3 8 and 5 1 for the four stages respectively twenty four hours after the rainstorm trigrs predicted that 1255 grid cells failed which is consistent with the field data iii trigrs generated more satisfactory results at a given precipitation threshold than sinmap which is ideal for landslide hazard zoning for land use planning at the regional scale comparison results showed that trigrs is more useful for landslide prediction for a certain precipitation threshold also in the regional scale iv analysis of the responses of loess slope prone to slope failure after different precipitation scenarios revealed that loess slopes are particularly sensitive to extended periods of heavy precipitation copyright 2016 john wiley sons ltd

laboratory characterization of rainfall induced loess slope failure loess slopes are widely distributed throughout the northwestern region of china and are prone to slope failure in response to heavy rainfall we undertook three groups of flume experiments in the laboratory to study loess slope dynamics under artificial rainfall conditions additionally a laser scanner was used to observe loess landslide deformation characteristics and failure development a numerical analysis of unsaturated seepage in loess slopes because of rainfall infiltration was performed moisture content pore water pressure and slope deformation were monitored to quantify the relationship between rainfall infiltration and loess slope stability movement of the wetting front near the slope surface was triggered by rainfall and related to rainfall intensity and duration which is consistent with the numerical solution rainfall infiltration increased pore water pressure producing gravity driven landslides we observed that landslide development began with local failure in the toe slope that gradually retreated toward the crown forming a multi sliding displacement and eventually resulting in total slope failure

three dimensional geophysical anatomy of an active landslide in lias group mudrocks cleveland basin uk a geoelectrical investigation of a slow moving earth slide earth flow in lower jurassic lias group rocks of the cleveland basin uk is described these mudrock slopes are particularly prone to failure and are a major source of lowland landslides in the uk but few attempts have been made to spatially or volumetrically characterise the subsurface form of these slides the primary aim of this study was to consider the efficacy of fully three dimensional geoelectrical imaging for landslide investigation with reference to a geological setting typical of lias group escarpments the approach described here included a reconnaissance survey phase using two dimensional electrical resistivity tomography ert resistivity mapping self potential sp profiling and mapping followed by a detailed investigation of an area of the landslide using three dimensional 3d ert and self potential tomography spt interpretation of the geophysical data sets was supported by surface observations aerial lidar and differential gps geomorphological surveys and intrusive investigations boreholes and auger holes the initial phase of the study revealed the existence of a strong sp signature at the site consistent with a streaming potential source and established the relationships between the main geological units the geomorphologic expression of the landslide and the resistivity of the materials in and around the study area the 3d spt model generated during the second phase of the study indicated drainage patterns across the landslide and preferential flow from the low permeability mud rocks into the underlying more permeable sandstone formation because of favourable resistivity contrasts between the clay rich whitby mudstone formation landslide material and the underlying staithes sandstone formation the volumetric 3d ert image allowed a number of surface and subsurface landslide features to be identified and spatially located these included the lateral extent of slipped material and zones of depletion and accumulation the surface of separation and the thickness of individual earth flow lobes and the dipping in situ geological boundary between the whitby mudstone and staithes sandstone bedrock formations