landslide hazard assessment in the three gorges area china using aster imagery wushan badong abstract the objectives of this study are to develop a methodology for regional scale assessment of landslide hazard using remotely sensed data and to produce a landslide hazard map of the wushan badong area in the three gorges china from advanced spaceborne thermal emission and reflection radiometer aster images the area is undergoing rapid urban development with slope instability causing a widespread natural hazard landslide related parameters were largely estimated through image processing and visual interpretation of aster multi spectral and topographic data we used field measurements to define the quantification for three parameters a slope angle in relation to lithology b distance to drainage network in relation to stream order and c distance to tectonic lineament in relation to lineament length we employed a multi parameter elimination and characterization model based on estimation of the geometric mean to remove areas where landslides are not expected to occur and classify the remaining areas into landslide hazard categories our results show increased landslide hazard in and around wushan and badong towns as well as other populated areas along the yangtze and its tributaries we used field data on landslide distribution to identify typical geomorphological settings for different landslide types and to provide ground control for the hazard assessment the results indicate good correlation between classified high hazard areas and field confirmed slope failures and show the usefulness of aster imagery for landslide hazard assessment at a regional scale

on the spatial relationship between landslides and causative factors on lantau island hong kong abstract this paper presents a statistical approach to study the spatial relationship between landslides and their causative factors at the regional level the approach is based on digital databases and incorporates such methods as statistics spatial pattern analysis and interactive mapping firstly the authors propose an object oriented conceptual model for describing a landslide event and a combined database of landslides and environmental factors is constructed by integrating the various databases within such a conceptual framework the statistical histogram spatial overlay and dynamic mapping methods are linked together to interactively evaluate the spatial pattern of the relationship between landslides and their causative factors a case study of an extreme event in 1993 on lantau island indicates that rainfall intensity and the migration of the center of the rainstorm greatly influence the occurrence of landslides on lantau island a regional difference in the relationship between landslides and topography is identified most of the landslides in the middle and western parts of the island occurred on slopes with slope angles of 25 35 while in the eastern part the corresponding range is 30 35 overlaying landslide data with land cover reveals that a large number of landslides occurred in the bareland and shrub covered area and in the transition zones between different vegetation types the proposed approach can be used not only to analyze the general characteristics of such a relationship but also to depict its spatial distribution and variation thereby providing a sound basis for regional landslide prediction

surface rupture during the 2010 mw 7 1 darfield canterbury earthquake implications for fault rupture dynamics and seismic hazard analysis the september 2010 m w 7 1 darfield canterbury earthquake in new zealand is one of the best recorded earthquakes of this magnitude the earthquake occurred on a previously unidentified fault system and generated a 29 5 0 5 km long surface rupture across a low relief agricultural landscape high accuracy measurements of coseismic displacements were obtained at over 100 localities along the greendale fault maximum net displacement d max 5 3 0 5 m and average net displacement d avg 2 5 0 1 m are anomalously large for an earthquake of this m w d max surface rupture length srl and d avg srl ratios are among the largest ever recorded for a continental strike slip earthquake geologically derived estimates of moment magnitude m w g are less than the seismologically derived m w derived using widely employed srl m w scaling regressions m w g is greater than m w using d max and d avg m w regressions the geologically derived static stress drop of 13 9 3 7 mpa provides a context with which to compare this earthquake rupture to interplate and intraplate ruptures of similar m w this data set provides fundamental information on fault rupture processes relevant to seismic hazard modeling in this region and analogous settings globally

mineral composition of sedimentary formations in the north atlantic ocean sedimentary formations established in the western north atlantic basin byjansa et al 1979 and their coeval counterparts from the eastern north atlantic were studied for their mineral composition using x ray powder diffractometry more than thousand samples from different legs of the deep sea drilling project were analysed semiquantitatively the results are presented as diagrams of about thirty five different mineral phases versus depth stratigraphy in the single boreholes sites 105 106 386 387 391 417 and 418 were studied from the western north atlantic and sites 367 369 370 415 and 416 from the eastern north atlantic off w africa specific mineral spectra were found from most of the formations which can thus be additionally characterized the change of mineral composition along the formation boundaries is in most cases sharp but along some of the boundaries it is transitional local variations of mineral spectra within the same formation can mainly be referred to distance from source areas the sedimentary section studied from the western north atlantic basin ranges in age from oxfordian to quaternary it consists of argillaceous limestones cat gap formation limestones blake bahama formation claystones and shales hatteras formation zeolitic claystones plantagenet formation nanno marls crescent peaks member siliceous oozes clays and cherts bermuda rise formation and hemipelagic muds blake ridge formation with locally redeposited shallow water carbonates great abaco member a corresponding section in the eastern north atlantic is only developed at site 367 where similar mineral assemblages could be found at sites 369 370 415 and 416 the sediment sequence is dominated by turbiditic influx of terrigenous components alternating with pelagic sediments this can clearly be depicted from the mineral suites but it is not possible to establish sedimentary formations which can be paralleled to those within the western north atlantic seismically mappable reflectors which were calibrated at the sediment sequence of the drillsites are in most cases related to lithological changes and mineral composition these acoustic horizons are very often coincident with formation boundaries besides different mineral composition changes in grain size and diagenesis but also erosional unconformities are responsible for the impedance contrasts leading to the reflectors as already pointed out bytucholke 1979

a record of glacial interglacial alternations in pleistocene sediments off new jersey expressed by clay mineral grain size and magnetic susceptibility data abstract clay mineral grain size and magnetic susceptibility measurements have been performed on a high resolution sampling of pleistocene clayey silts and silty clays drilled at odp site 902 hole d located on the upper slope off new jersey nw atlantic the combination of data from different techniques and their comparison with 18 o and gamma ray attenuation porosity evaluator grape data allow us to clearly distinguish between sediments deposited during glacial and interglacial cycles glacial sediments are poorly sorted rich in either clay or sand and characterized by the abundance of chlorite and high magnetic susceptibility values in contrast interglacial sediments are well sorted silt dominated and poor in chlorite the hudson river and its tributaries draining the appalachian highlands appear to constitute the perennial sources of the detrital input including quartz feldspars amphibole and a clay fraction dominantly composed of illite random mixed layers and kaolinite during glacial stages the terrigenous sedimentation was enhanced by additional input of chlorite from glacial erosion in northeastern america the variations in chlorite amounts supplied to the ocean were probably controlled by the ice sheet advances and retreats these variations are quantified by the kaolinite chlorite ratio k c which constitutes a reliable marker of glacial and interglacial influences on the terrigenous sedimentation

a new practical method for prediction of geomechanical failure time abstract predicting the failure time of geo hazards is an important rock mechanics problem we first evaluated the validity of the inverse velocity inv method to predict failure time of rock mass and landslides this method utilizes rates of displacement or strain to predict the actual failure time tf so the value of total displacement or strain before failure is not crucial second we developed a new method for computing failure time predictions based on the slope gradient to predict tf termed the slo method finally a simple conceptualised model representing safe and unsafe predictions was proposed to validate these hypotheses prediction of rock mass failure in the asamushi and vaiont landslides in situ studies was conducted furthermore laboratory conditions were incorporated into the research which include predictions using circumferential strain and axial strain from uniaxial compression creep test on shikotsu welded tuff swt and predictions of failure time for inada granite under brazilian creep tests it was found that the slo method is better than the inv method slo gave safe predictions in all the cases in contrast inv tends to give unsafe predictions predicted failure time tfp tf our findings reveal that predictions using circumferential strain are better than those made using axial strain for swt and notably given failure with very short tertiary creep the methods tend to show limited reliability however the slo method could find extensive application in predicting failure time of geo hazards for instance roof wall failure in mines etc

application of wavelet analysis and a particle swarm optimized support vector machine to predict the displacement of the shuping landslide in the three gorges china landslides occur frequently in the three gorges in china posing threats to human life and the normal operation of the three gorges dam a number of preexisting landslides have been reactivated since the initial impoundment of the three gorges reservoir in june 2003 an effective and accurate method of predicting landslide displacement is necessary to mitigate the effects of these disastrous landslides this study carries out a landslide displacement prediction for the shuping landslide using 7 years of monitoring data wavelet analysis and a particle swarm optimized support vector machine pso svm model the landslide s displacement is strongly influenced by periodic precipitation and reservoir level fluctuations and the cumulative displacement curve versus time indicates a step like character based on the deformation characteristics of this landslide the total displacement is divided into its trend and periodic components by means of the wavelet analysis an s curve estimation is used to predict the trend displacement via the curve fitting of the historical displacement versus time five primary factors are used as the input variables for a pso svm model to predict periodic displacement these factors include cumulative precipitation over the previous month cumulative precipitation during a two month period maximum continuous decrement in the reservoir level during the current month and cumulative increments and decrements in the reservoir level during the current month the mean squared error squared correlation coefficient and akaike s information criterion of the wavelet pso svm model at gps monitoring points zg85 and zg87 are 2 45 0 945 and 20 80 and 10 46 80 981 and 36 38 respectively this method can be applied to the prediction of displacement in colluvial landslides in the three gorges this study may provide useful information to engineers and planners involved in landslide prevention and reduction

mechanism of the anlesi landslide in the three gorges reservoir china abstract many gentle dip translational rock slides have taken place in the three gorges reservoir china in order to study the mechanism of these translational rock slides the authors use the anlesi landslide as a typical case study to investigate in detail field investigations show that the slip zones of the anlesi landslide were formed from a white mudstone in jurassic red strata x ray diffraction and infrared ray analysis showed that the main mineral components of the slip zones are montmorillonite illite feldspar and quartz laboratory tests indicate that the slip zone soils are silty clay of medium swelling potential the shear strength decreasing significantly as the slip zone attracts water and saturates the main factors contributing to the anlesi landslide are recent tectonic activity incompetent beds and intensive rainfall recent tectonic activity had caused shear failure along the incompetent beds and joints within the sandstone with the effect of intensive rainfall water percolates to the incompetent beds along tectonic fissures resulting in swelling of the soil material and high groundwater pressures within fissures in the strata as a consequence the anlesi slope is prone to slide along these incompetent beds flac3d software was used to simulate the mechanism of the anlesi landslide considering the rheological properties of soil and rock the simulation results demonstrate that the stress displacement and failure area changes with simulated creep time the maximum displacement in the x direction reaches 7 59 m after 200 year simulated creep therefore the mechanism of the anlesi landslide can be illustrated considering the rheological properties of jurassic red strata

landslide susceptibility mapping using rough sets and back propagation neural networks in the three gorges china in the three gorges of china there are frequent landslides and the potential risk of landslides is tremendous an efficient and accurate method of generating landslide susceptibility maps is very important to mitigate the loss of lives and properties caused by these landslides this paper presents landslide susceptibility mapping on the zigui badong of the three gorges using rough sets and back propagation neural networks bpnns landslide locations were obtained from a landslide inventory map supported by field surveys twenty two landslide related factors were extracted from the 1 10 000 scale topographic maps 1 50 000 scale geological maps landsat etm satellite images with a spatial resolution of 28 5 m and hj a satellite images with a spatial resolution of 30 m twelve key environmental factors were selected as independent variables using the rough set and correlation coefficient analysis including elevation slope profile curvature catchment aspect catchment height distance from drainage engineering rock group distance from faults slope structure land cover topographic wetness index and normalized difference vegetation index the initial three layered and four layered bpnn were trained and then used to map landslide susceptibility respectively to evaluate the models the susceptibility maps were validated by comparing with the existing landslide locations according to the area under the curve the four layered bpnn outperforms the other two models with the best accuracy of 91 53 approximately 91 37 of landslides were classified as high and very high landslide prone areas the validation results show sufficient agreement between the obtained susceptibility maps and the existing landslide locations

spatiotemporal deformation characteristics and triggering factors of baijiabao landslide in three gorges reservoir region china abstract variations of reservoir water level and seasonal precipitation have resulted in significant movement and destabilization of landslides in the three gorges reservoir tgr region of china since reservoir impoundment in 2003 an example is the baijiabao landslide a large actively creeping landslide located in the steep lower valley of the xiangxi river about 55 km upstream of the tgr dam in the yangtze river twelve years of monthly monitoring at four gps stations and routine monthly field observations show cumulative gps displacements as large as 1 5 m and widely developed ground cracks gps monitoring results show that most movement takes place in rapid steps that coincide with the rainy season and the period of annual reservoir drawdown with particularly large steps in 2009 2012 and 2015 this step like pattern of displacement is also shown by daily data from an automatic monitoring system installed in 2017 the total period of acceleration shown by these daily data was about six weeks long with rapid movement starting during rapid reservoir drawdown and terminating when the reservoir began to rise again in particular most of the 2018 displacement occurred in only two weeks different subzones of the landslide move at different rates and exhibit different features of deformation the neighborhood rough set theory is used to identify the triggering factors responsible for landslide deformation the most important triggering factors vary between different sites data types and the time interval used to define them the surface deformation and ground crack widening are controlled by the combination of rainfall and variations in the reservoir water levels whereas the deformation of the sliding zone is most sensitive to the latter the results show that daily data are needed to capture important short term landslide responses the neighborhood rough set theory for determination of triggering factors is suggested for deformation prediction stability evaluation and prevention and control of reservoir landslides in this and other regions

hydrological triggering conditions of landslides in varved clays in the french alps abstract in this paper the meteorological and hydrological conditions are analyzed which trigger shallow and deeper landslides in glacio lacustrine deposits varved or laminated clays in the french alps the hydrological system of these landslides consists of a colluvial cover which supplies water into the fissures of the underlying varved clays from these fissures water can infiltrate more or less horizontally into the silt layers of the varved clays a combined reservoirs model was used to simulate the water fluctuations in the colluvial cover and the fissures both the water level in the fissures and the residence time of water in the fissures are mainly controlled by the amount of water storage in the colluvial cover simulations over the last 25 years show that almost each year the fissures are completely filled with water for several months a year infiltration experiments in the field show that infiltration into the varved clays occurs mainly by horizontal infiltration into the silt laminae calculated infiltration rates from these fissures into the silt layers show that the mean yearly residence time of water in the fissures is not sufficient to fully saturate the clay mass each year it is therefore concluded that the triggering of the landslide movements is mainly controlled by the development of positive pore water pressures in the fissure system and that the rise of pore water pressures induced by the matrix system of the varved clays only plays a minor role the calculations also show that drainage of the colluvial cover is a very efficient measure to stabilize the deeper landslides

regression models for estimating coseismic landslide displacement newmark s sliding block model is widely used to estimate coseismic slope performance early efforts to develop simple regression models to estimate newmark displacement were based on analysis of the small number of strong motion records then available the current availability of a much larger set of strong motion records dictates that these regression equations be updated regression equations were generated using data derived from a collection of 2270 strong motion records from 30 worldwide earthquakes the regression equations predict newmark displacement in terms of 1 critical acceleration ratio 2 critical acceleration ratio and earthquake magnitude 3 arias intensity and critical acceleration and 4 arias intensity and critical acceleration ratio these equations are well constrained and fit the data well 71 br 2 b88 but they have standard deviations of about 0 5 log units such that the range defined by the mean one standard deviation spans about an order of magnitude these regression models therefore are not recommended for use in site specific design but rather for regional scale seismic landslide hazard mapping or for rapid preliminary screening of sites 2007 elsevier b v all rights reserved

mechanism and failure process of qianjiangping landslide in the three gorges reservoir china the qianjiangping landslide is a large planar rock slide which occurred in july 14 2003 shortly after the water level reached 135 m in the three gorges reservoir china the landslide destroyed 4 factories and 129 houses took 24 lives and made 1 200 people homeless field investigation shows that the contributing factors for the landslide are the geological structure of the slope the previous surface of rupture the water level rise and continuous rainfall in order to reveal the mechanism and failure process of the landslide numerical simulation was conducted on qianjiangping slope before sliding based on the characteristics and the engineering conditions of the landslide the topography and the geological profiles of qianjiangping slope before sliding is reconstructed the seepage field of qianjiangping slope before sliding was simulated with the geostudio software the results show that ground water table rises and bends to the slope during the rise of water level and the slope surface becomes partially saturated within the period of continuous rainfall using the ground water table obtained above the failure process of qianjiangping slope is simulated with the flac3d software the results demonstrate that the shear strain increment displacement and shear failure area of the slope increased greatly after the water level rose and continuous rained and the landslide was triggered by the combined effect both of water level rise and continuous rainfall the development of shear strain increment displacement and shear failure area of the slope shows that the landslide was retrogressive in the lower part of the slope and progressive in the upper part of the slope

groundwater responses to the recent canterbury earthquakes a comparison summary the recent canterbury christchurch earthquakes and aftershocks generated groundwater level responses throughout new zealand however the greater part of damage has been sustained by the city of christchurch which is built on a layered sequence of artesian aquifers in this paper we focus on responses in these coastal aquifers we quantify groundwater responses with a simple model which differentiates between immediate earthquake induced response spike and post seismic change offset the most significant feature of our analysis is the consistent pattern of groundwater response to the earthquakes deeper wells correlate with negative offset and shallower wells correlate with positive offset this is consistent with the upwards vertical movement of water we consider the hydrological and engineering consequences

impact of reservoir impoundment caused groundwater level changes on regional slope stability a case study in the loess plateau of western china due to its impact on regional groundwater levels the impoundment of a reservoir is an important consideration for assessing the stability of surrounding slopes this study presents a method for risk assessment and control of landslides in regions where groundwater levels can be affected by reservoir water levels the method is illustrated with a case study of the hongzhuang reservoir in yanan city northern shaanxi province china a groundwater numerical model was developed using modflow and the groundwater flow fields were calculated for different reservoir water levels safety factors were then obtained and the slope stability was analyzed moreover a probabilistic slope analysis was performed by monte carlo simulation to evaluate the reliability of slope stability and the probability of slope failure finally a reasonable reservoir water level was determined according to the acceptable risk level and a comprehensive risk mitigation method was proposed considering water level control relocation and drainage measures

the analysis of rainfall induced slope failures at iva valley area of enugu state nigeria this paper analyses the dominant mechanisms of slope failures and identifies potential obstacles to landslide hazard reduction at the iva valley area enugu nigeria the landscape is replete with landslide scars and gullies of varied sizes and the slope deposits comprise unconsolidated friable sands inter bedded with thin units of montmorillonitic claystone forty three landslide events were identified in the study area with most being shallow short run out movements with slip surface depth 2 m the study found the landslides mainly occur in the beginning of rainy season characterized by short duration high intensity rainfall an integrated approach comprising field mapping laboratory tests and numerical analyses reveals that the barren nature of the slopes prior to the outset of rainy season high rainfall intensity erosion overgrazing soil characteristics and the site s unique lithologic sequence are the main causes of instability shearing tests under several conditions showed that the soils strongly strain soften until low steady state strength is achieved a computer code based on this strength reduction technique used input parameters obtained from the field and laboratory studies to simulate a landslide with similar structure travel distance and distribution area it is noted that urbanization has gradually increased the vulnerability of the society s poor to landslide hazards as they now erect unplanned residence tents and blocks on the slopes this work is part of a regional study aimed at finding ways of protecting the vulnerable by generating data that could be used to build future landslide susceptibility map

clay mineral associations and structural evolution of the south atlantic jurassic to eocene abstract clay minerals have been used to reconstruct the geological history of the south atlantic six mineralogical stages have been recognized from the middle jurassic to the eocene 1 1 prior to the oxfordian illite irregular mixed layers and kaolinite marked a period of tectonic extension between africa and antarctica 2 2 from the oxfordian to the early albian smectites developed during subsidence induced peneplanation of the relief along the southern margin while chlorite illite irregular mixed layers and kaolinite characterized a distensive regime in the cape and southern angola basins 3 3 from the albian to the early turonian smectites palygorskite and sepiolite linked to subsidence processes occurred from the southern ocean to the southern angola basin while chlorite illite irregular mixed layers and kaolinite characterized tectonic extension from gabon to nigeria 4 4 from the early turonian to the early campanian smectites palygorskite and sepiolite linked to subsidence were widespread in the south atlantic areas 5 5 from the early campanian to early paleocene chlorite illite irregular and subregular mixed layers and kaolinite marked a reactivation of continental reliefs in the northern areas of the south atlantic in relation to compression in nigeria and opening of the equatorial atlantic 6 6 after the early paleocene smectites palygorskite and sepiolite characterized the widespread subsidence in the south atlantic

relationship between earthquake induced excess pore water pressure and strong ground motion observed in a monitored fill slope abstract the generation of excess pore water pressures during ground shaking can be an important earthquake induced landslide trigger we measured pore water pressures and seismic ground motion in filled slopes and examined their relationships obtained from 29 observed earthquakes we characterized pore water pressure and seismic waveforms by calculating several parameters that described their magnitudes and durations we demonstrate that whilst the instantaneous magnitude of strong ground motion is responsible for the generation of excess pore water pressure the magnitude of excess pore water pressure generated is related to the peak ground acceleration pga and arias intensity ai in the observed pga range of 0 12 1 9 m s2 the magnitude of peak ground velocity pgv also produced a strong correlation although a few exceptional events where long period component 1 s of seismic waves is dominant were observed lastly the time span over which excess pore water pressure continues to rise is affected by the duration of seismic ground motion our study shows how excess pore water pressures can be generated in fill slopes during seismic events this new knowledge could be used to improve future earthquake induced landslide hazard assessment

d insar based landslide location and monitoring at wudongde hydropower reservoir in china differential synthetic aperture radar interferometry d insar has become a useful technique for monitoring ground movement the technique enables the analysis of very small ground movements in continuous large areas and has the advantages of high accuracy high resolution all weather adaptability low cost and inaccessible area coverage thus d insar has been widely used in the investigation of geologic hazards such as subsidence landslide earthquake and volcanic activity in this paper d insar is used to locate and monitor landslide movement in the wide area of wudongde hydropower reservoir in jinsha river china five sar acquisitions are obtained by using the phased array type l band synthetic aperture radar sensor of the advanced land observing satellite detailed moving displacement maps in two time periods are derived by using the d insar technique and potentially moving landslide areas as well as landslide hazard areas are then located the l1r 6 landslide which is in active state is investigated in detail the deforming tendency obtained via d insar is consistent with that obtained via global positioning system gps monitoring error analysis of the d insar results is also conducted finally the grid function interpolation method of error reduction which combines d insar and gps is proposed to reduce the single point error in d insar monitoring and is further verified by the considerable improvement in the accuracy of l1r 6 landslide monitoring

analysis of baishuihe landslide influenced by the effects of reservoir water and rainfall since the impoundment of the three gorges reservoir in june 2003 a number of new landslides have occurred and existing landslides have been made worse the 1 260 104 m3 baishuihe landslide located at 56 km west of the three gorges dam began to deform more noticeably after the first impoundment in early july 2003 the sliding of the two blocks comprising the landslide one an active block and the other a relatively stable block became apparent after approximately 5 years of monitoring field recordings show that the landslide displacement is affected by the combined effects of the rainfall and water level in the reservoir these effects have been investigated in the present paper including the deformation characteristics movement pattern direction displacement and velocity earmarking the temporal evolution of the active block based on a practical creep model of a large rock slide alert velocity thresholds for pre alert alert and emergency phases have been computed corresponding to the imminence of failure the alert velocity thresholds are being proposed to be included as a part of an early warning system of an emergency plan drawn up to minimize the adverse impact in the event of landslide failure the emergency plan is intended to be implemented as a risk management tool by the relevant authorities of the three gorges reservoir in the near future

paleoenvironmental history of the north atlantic region from mineralogical and geochemical data abstract principles and applications of inorganic mineralogy and geochemistry in reconstructing past environments in marine basins are summarized by means of two examples from north atlantic deep sea drilling sites the first approach is chronological and permits by comparing the hatteras and cape verde basins since the oxfordian to identify the effects of continental and marine influences land climate and morphological evolution alternation of tectonically active and stable periods ocean deepening and widening stages and latitudinal migration of lithospheric plates the second approach more recently developed concerns the geographic distribution of paleoenvironments during albian time particularly the role of the bermuda area as a submarine barrier separating the western and eastern detrital input and the contrast between the stable american margin that favored pedologic processes on land and the unstable african margin characterized by strong erosion resedimentation and volcanic processes

mineralogy of sedimentary formations in the western north atlantic ocean preliminary results six sedimentary formations and two separate members recently were described byjansa et al 1979 from the western north atlantic ocean basin we have investigated the mineralogical composition of these lithostratigraphic units by qualitative x ray diffraction analyses of about five hundred samples from dsdp sites 105 106 386 387 and 391 the sedimentary section studied from bottom to top consists of argillaceous limestones cat gap formation limestones blake bahama formation claystones and shales hatteras formation zeolitic claystones plantagenet formation nannofossil marls crescent peaks member siliceous oozes clays and cherts bermuda rise formation and hemipelagic muds blake ridge formation that locally contain redeposited shallow water carbonates great abaco member the section ranges in age from oxfordian at the base to quaternary at the sea floor

application of a two step cluster analysis and the apriori algorithm to classify the deformation states of two typical colluvial landslides in the three gorges china several extensive landslides have occurred in the vicinity of the three gorges reservoir since its initial impoundment in june 2003 a reduction of the landslide risk is essential for the safety and security of lives and property in the region this study analyses the deformation states of two typical colluvial landslides the baijiabao and laoshewo landslides using 6 years of monitoring data a two step cluster analysis and the apriori algorithm the landslide displacement versus time curves exhibit step like patterns and the landslide deformation is highly correlated with fluctuations in the reservoir level and seasonal precipitation to determine different types of landslide deformation the monthly displacement curves of the colluvial landslides are classified into three types using a two step cluster analysis initial deformation constant deformation and rapid deformation five driving factors were selected as the antecedents for the apriori algorithm to obtain rules that describe the relationships between the landslide deformation and the influential parameters these factors include the cumulative precipitation over the previous month the maximum daily precipitation during the current month changes in the reservoir level over the previous month cumulative increases in the reservoir level and the average reservoir level during the current month the analytical results were validated by comparing them with observed landslide deformation characteristics using three measurement standards support confidence and lift the results show that the combined method of a two step cluster analysis with the apriori algorithm can effectively model the landslide deformation states that are associated with the baijiabao and laoshewo landslides moreover this method may serve as a potential reference for deformation analyses of colluvial landslides in the three gorges