regional scale co seismic landslide assessment using limit equilibrium analysis abstract traditionally regional assessment of seismic slope stability has been done using the infinite slope rigid sliding block analysis a major disadvantage of this approach is the resulting overestimation of the critical acceleration of the slope due to the underlying assumption of a predefined slope failure plane and consequently the underestimation of hazard areas prone to sliding in this paper we present a modified approach for assessing seismic slope instabilities using a model based on limit equilibrium analysis and circular slip surfaces with no restriction to any predefined slope failure plane for this purpose we conduct a parametric study to identify the relationship between the critical acceleration of the slope the slope angle and the slope shear strength parameters we model typical slopes in the rocscience software slide using bishop s limit equilibrium method to identify the critical accelerations that corresponds to a failure plane with factor of safety equal to one the critical accelerations were plotted against the variables in the parametric study and the best fit equations were obtained the proposed approach was developed for global application but it was tested using the well documented co seismic landslide database of the 1994 northridge ca earthquake the predicted sliding areas were compared to the inventory of landslides that were triggered in the val verde region in los angeles by the earthquake qualitative and quantitative assessments of the proposed model clearly show its advantages in predicting potential sliding areas

instability of saturated and unsaturated coarse granular soils abstractit is well known that saturated silt and fine sand are susceptible to instability during undrained shearing coarse granular soils may also be unstable during undrained shearing or during rainfall infiltration starting at an unsaturated state this paper investigates the instability of three saturated and unsaturated granular soils with different fines contents f 50 32 and 10 isotropic consolidation tests and mercury intrusion porosimetry tests were first conducted to investigate the instability of the microstructures of these granular soils then drained and undrained triaxial tests were conducted to investigate the instability behavior under the saturated condition subsequently wetting tests under the constant shear stress condition were carried out on unsaturated specimens to investigate the instability of the same soils during water infiltration the instability in the microstructures is in accordance with the compressibility of the soils the instability during undrained shearing under

impact of the 2008 wenchuan earthquake in china on subsequent long term debris flow activities in the epicentral area abstract the 2008 wenchuan earthquake triggered the largest number of landslides among the recent strong earthquake events around the world the loose landslide materials were retained on steep terrains and deep gullies in the period from 2008 to 2015 numerous debris flows occurred during rainstorms along the provincial road 303 pr303 near the epicentre of the earthquake causing serious damage to the reconstructed highway approximately 5 24 10 6 m 3 of debris flow sediment was deposited shortly after the earthquake this paper evaluates the evolution of the debris flows that occurred after the wenchuan earthquake which helps understand long term landscape evolution and cascading effects in regions impacted by mega earthquakes with the aid of a gis platform combined with field investigations we continuously tracked movements of the loose deposit materials in all the debris flow gullies along an 18 km reach of pr303 and the characteristics of the regional debris flows during several storms in the past seven years this paper presents five important aspects of the evolution of debris flows 1 supply of debris flow materials 2 triggering rainfall 3 initiation mechanisms and types of debris flows 4 runout characteristics and 5 elevated riverbed due to the deposited materials from the debris flows the hillslope soil deposits gradually evolved into channel deposits and the solid materials in the channels moved towards the ravine mouth accordingly channelized debris flows became dominant gradually due to the decreasing source material volume and changes in debris flow characteristics the triggering rainfall tends to increase from 30 mm h 1 in 2008 to 64 mm h 1 in 2013 and the runout distance tends to decrease over time the runout materials blocked the river and elevated the riverbed by at least 30 m in parts of the study area the changes in the post seismic debris flow activity can be categorized into three stages i e active unstable and recession

role of vegetation restoration in mitigating hillslope erosion and debris flows abstract after the 2008 wenchuan earthquake a large amount of loose landslide deposits was left in the stricken region a heavy storm in 2010 turned numerous deposits into debris flows after 2010 vegetation gradually recovered on the remnant soil deposits during the wet seasons in 2013 and 2015 the number of debris flows decreased significantly compared with that in 2010 this paper investigates the role of vegetation in mitigating runoff induced hillslope erosion and debris flows the study slope is near the epicentre of the wenchuan earthquake three levels of vegetation restoration are considered bare in 2010 middle level in 2013 and high level in 2015 soil samples were taken from the landslide deposits to determine the root mass density which is used to quantify erosion resistance parameters at different vegetation levels massive erosion is simulated in the 2010 case which in turn develops into hillslope debris flows very little or no erosion is simulated in the 2013 and 2015 cases which is in part attributed to the enhanced resistance to erosion by restored vegetation a parametric study is conducted to further investigate the effectiveness of erosion reduction through revegetation

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

landslides induced by the wenchuan earthquake and the subsequent strong rainfall event a case study in the beichuan area of china abstract the wenchuan earthquake on may 12 2008 triggered massive landslides and a subsequent strong rainfall prompted the development of new landslides as well as the reactivation of some pre existing landslides the highest seismic intensity zone of the wenchuan earthquake in beichuan china was selected as a case study to analyze the influence of the earthquake and the subsequent heavy rains on landslide evolution we selected this study area 414 km 2 since it was close to the coseismic surface rupture and because it suffered strong ground motion based on the interpretation of high resolution aerial photographs and remote sensing imagery combined with field investigation 40 pre earthquake landslides and 2221 coseismic landslides were identified with total landslide areas of 2 68 km 2 and 30 81 km 2 respectively there were 134 large over 50 000 m 2 co seismic landslides that covered a surface area of 15 54 km 2 and represented approximately 50 4 of the total area of the co seismic landslides the coseismic landslides were mainly located on the hanging wall of the causative fault and on the steep valley sides of the jian river and its tributaries a strong rainfall event occurred four months after the wenchuan earthquake and induced 969 new landslides which covered a 6 90 km 2 area and enlarged 169 existing landslides 2 48 km 2 the landslides were identified in spot5 images ultimately we found that earthquake tremors and the subsequent rainstorm severely disturbed the surface strata resulting in a large number of landslides

distribution pattern of earthquake induced landslides triggered by the 12 may 2008 wenchuan earthquake abstract this paper presents the preliminary results of an extensive study of the mapping the distribution of landslides triggered by the wenchuan earthquake in sichuan province china on 12 may 2008 an extensive landslide interpretation was carried out using a large set of optical high resolution satellite images e g aster alos cartosat 1 spot 5 and ikonos as well as air photos for both the pre and post earthquake situation landslide scarps were mapped as points using multi temporal visual image interpretation taking into account shape tone texture pattern elevation and ridge and valley orientation nearly 60 000 individual landslide scarps were mapped the landslide distribution map was compared with the inventory map that was prepared directly after the earthquake which contains about 11 000 individual landslide points through the calculation of normalized landslide isopleths maps remarkable differences were observed as the earlier inventory mapping did not consider the pre earthquake situation and did not consider all individual landslides as part of the landslide inventory landslides were identified that had blocked the drainage and had formed landslide dams the landslide distribution was compared with a number of aspects such as the seismic parameters distance to epicenter distance to fault rupture co seismic fault geometry and co seismic slip distribution and geology the most remarkable correlation found was with the co seismic slip distribution and the fault geometry landslide distribution in the section of the fault that had mainly a thrust component with low angle fault plane was found to be much higher than the sections that had steeper fault angles and a major strike slip component

warm ocean is eroding west antarctic ice sheet 1 satellite radar measurements show that ice shelves in pine island bay have thinned by up to 5 5 m yr 1 over the past decade the pattern of shelf thinning mirrors that of their grounded tributaries the pine island thwaites and smith glaciers and ocean currents on average 0 5 c warmer than freezing appear to be the source the synchronised imbalance of the inland glaciers is the result of reduced lateral and basal tractions at their termini and the drawdown of grounded ice shows that antarctica is more sensitive to changing climates than was previously considered

modelling circumpolar deep water intrusions on the amundsen sea continental shelf antarctica results are presented from an isopycnic coordinate model of ocean circulation in the amundsen sea focusing on the delivery of circumpolar deep water cdw to the inner continental shelf around pine island bay the warmest waters to reach this region are channeled through a submarine trough accessed via bathymetric irregularities along the shelf break temporal variability in the influx of cdw is related to regional wind forcing easterly winds over the shelf edge change to westerlies when the amundsen sea low migrates west and south in winter spring this drives seasonal on shelf flow while inter annual changes in the wind forcing lead to inflow variability on a decadal timescale a modelled period of warming following low cdw influx in the late 1980 s and early 1990 s coincides with a period of observed thinning and acceleration of pine island glacier

statistical analysis of factors affecting landslide distribution in the new madrid seismic zone tennessee and kentucky abstract more than 220 large landslides along the bluffs bordering the mississippi alluvial plain between cairo ill and memphis tenn are analyzed by discriminant analysis and multiple linear regression to determine the relative effects of slope height and steepness stratigraphic variation slope aspect and proximity to the hypocenters of the 1811 12 new madrid mo earthquakes on the distribution of these landslides three types of landslides are analyzed 1 old coherent slumps and block slides which have eroded and revegetated features and no active analogs in the area 2 old earth flows which are also eroded and revegetated and 3 young rotational slumps which are present only along near river bluffs and which are the only young active landslides in the area discriminant analysis shows that only one characteristic differs significantly between bluffs with and without young rotational slumps failed bluffs tend to have sand and clay at their base which may render them more susceptible to fluvial erosion bluffs having old coherent slides are significantly higher steeper and closer to the hypocenters of the 1811 12 earthquakes than bluffs without these slides bluffs having old earth flows are likewise higher and closer to the earthquake hypocenters multiple regression analysis indicates that the distribution of young rotational slumps is affected most strongly by slope steepness about one third of the variation in the distribution is explained by variations in slope steepness the distribution of old coherent slides and earth flows is affected most strongly by slope height but the proximity to the hypocenters of the 1811 12 earthquakes also significantly affects the distribution the results of the statistical analyses indicate that the only recently active landsliding in the area is along actively eroding river banks where rotational slumps formed as bluffs are undercut by the river the analyses further indicate that the old coherent slides and earth flows in the area are spatially related to the 1811 12 earthquake hypocenters and were thus probably triggered by those earthquakes these results are consistent with findings of other recent investigations of landslides in the area that presented field historical and analytical evidence to demonstrate that old landslides in the area formed during the 1811 12 new madrid earthquakes results of the multiple linear regression can also be used to approximate the relative susceptibility of the bluffs in the study area to seismically induced landsliding

perturbation of fluvial sediment fluxes following the 2008 wenchuan earthquake quantifying the removal of co seismic landslide material after a large magnitude earthquake is central to our understanding of geomorphic recovery from seismic events and the topographic evolution of tectonically active mountain ranges in order to gain more insight into the fluvial erosion response to co seismic landslides we focus on the sediment fluxes of rivers flowing through the rupture zone of the 2008 m w 7 9 wenchuan earthquake in the longmen shan of the eastern tibetan plateau over the post seismic period of 2008 2013 we annually collected river sediment samples 0 25 1mm at 19 locations and measured the concentration of cosmogenic be 10 in quartz when compared with published pre earthquake data the be 10 concentrations declined dramatically after the earthquake at all sampling sites but with significant spatial differences in the amplitude of this decrease and were starting to increase toward pre earthquake level in several basins over the 5 year survey our analysis shows that the amplitude of be 10 decrease is controlled by the amount of landslides directly connected to the river network calculations based on be 10 mixing budgets indicate that the sediment flux of the 0 25 1mm size fraction increased up to sixfold following the wenchuan earthquake our results also suggest that fluvial erosion became supply limited shortly after the earthquake and predict that it could take a few years to several decades for fluvial sediment fluxes to go back to pre earthquake characteristics depending on catchment properties we also estimate that it will take at least decades and possibly up to thousands of years to remove the co seismic landslide materials from the catchments in the longmen shan copyright c 2017 john wiley sons ltd

spatial distribution analysis of landslides triggered by 2008 5 12 wenchuan earthquake china abstract the 2008 5 12 wenchuan earthquake seismic magnitude mw 7 9 according to the usgs triggered a great number of landslides a spatial database of landslides is built by interpreting the remote sensing rs data which covers 11 counties severely damaged by the earthquake with area of about 31 686 12 km2 the geological settings of the study area are detailed mapped including geologic structure and lithology the digital elevation model dem of the study area with resolution of 30 m 30 m is presented to address the topographic characteristics correlations between the occurrence of landslides with geological settings i e active faults the coseismic surface ruptures geological unit slope gradient slope elevation as well as slope aspect are analyzed using spatial modeling in gis with the aids of field investigations it can be concluded that the distance to the causative faults and slope gradient are much more important than other factors landslides are clustered distributed along the causative faults of f2 and f3 and landslides incidence are dramatically decreasing with the increasing of the distance to the causative faults the landslides incidence has an obvious increase near the active faults i e f1 landslide concentration lc landslides km2 has an obvious exponent increase with slope gradient however lc has no obvious relationship with geological unit and slope elevation the difference of lc value in each geological unit each slope elevation category maybe have been the result affected by slope gradient for each geological unit each slope elevation category and distance of each geological unit each slope elevation category to causative fault zone isoseismal map reflects the incidence of landslides in some degree and lc increases dramatically with intensity increasing almost all landslides occurred in the region above vi degree statistics result also indicates that in the near field of causative faults landslides tend to have the initial sliding direction similar to the movement of the causative faults and preliminary study shows that landslides incidence varies in different slopes with different structure and consequent slopes and obsequent slopes have a higher landslides incidence than other layered slopes

a physically based multi hazard risk assessment platform for regional rainfall induced slope failures and debris flows abstract rainfall induced slope failures and debris flows are two major hazards in mountainous areas a physically based multi hazard risk assessment platform for regional rainfall induced slope failures and debris flows has been developed in this study the platform enables prompt assessment of risks posed by regional rainfall induced slope failures and debris flows across multiple catchments which is required in landslide risk management in a large area it considers the contribution of slope failures to debris flows and the scenario of a location impacted by multiple slope failures or debris flows or both the contribution of slope failures to debris flows is considered by adding the increased amount of channel deposit from slope failures to the source material of debris flows the platform is applied to a highway near the epicentre of the 2008 wenchuan earthquake the platform predicts the impact areas and runout distances of regional debris flows reasonably well the risk assessment results indicate that both slope failures and debris flows pose a great danger to travellers along the road shortly after the earthquake due to the presence of a large amount of loose landslide deposits on steep terrains the materials from the slope failures triggered during a storm substantially increase the channel deposit volume leading to significantly increased debris flow volume and risk a multi hazard risk assessment approach is necessary to consider the scenario of a location impacted by multiple slope failures or debris flows or both since assessing risks of slope failures and debris flows separately may underestimate the risk

presenting regional shallow landslide movement on three dimensional digital terrain abstract a storm can trigger numerous shallow landslides on hilly terrains this paper presents a distributed cell model for presenting regional shallow landslide movement on a three dimensional digital terrain the model consists of five components namely a digital terrain module a spatial rainfall distribution module an infiltration analysis module a slope stability evaluation module and a movement prediction module the locations and volumes of landslides are analyzed first through rainfall infiltration and slope stability analyses the detached material is assumed to move along the steepest path from one cell to a lower cell empirical equations that are developed based on local landslide inventories are adopted as a landslide movement cessation criterion the effect of landslide size on travel distance is considered by grouping unstable cells that are bounded at least at one side or corner the uncertainties in soil shear strength parameters and the landslide movement process are considered in determining the possible bounds of travel distance the movement analysis method is applied to a 164 5 km 2 hilly terrain in the wenchuan earthquake zone to test its performance in presenting regional shallow landslide movement the method predicts the volume of landslides reasonably well the observed and computed movement traces and deposition locations of the detached material also agree reasonably well the volume of individual landslide and travel distance may be substantially underestimated if the size effect is not considered

observed subsurface signature of southern ocean sea level rise satellite altimetry data show a strong increase in sea level in various parts of the southern ocean over the 1990s in this paper we examine the causes of the observed sea level rise in the region south of australia using 13 years of repeat hydrographic data from the woce sr3 sections and the survostral xbt and surface salinity data the hydrographic data show a poleward shift in the position of the subtropical and the subantarctic fronts over the period in the antarctic zone the antarctic surface water has become warmer and fresher and the winter water tongue has become warmer fresher thinner and shallower increased freshening south of the polar front is linked to increased precipitation over the 1990s temperature changes over the upper 500 m account for only part of the altimetric sea level rise the ctd sections show that the deeper layers are also warmer and slightly saltier and the observed sea level can be explained by steric expansion over the upper 2000 m enso variability impacts on the northern part of the section and a simple sverdrup transport model shows how large scale changes in the wind forcing related to the southern annular mode may contribute to the deeper warming to the south

circumpolar structure and distribution of the antarctic circumpolar current fronts 2 variability and relationship to sea surface height 1 in part 1 of this study we showed that the antarctic circumpolar current acc consisted of multiple fronts each of which was consistently associated with a particular contour of sea surface height ssh or approximate streamline in part 2 we have used maps of ssh to examine the variability of the acc fronts between 1992 and 2007 the ssh label associated with each frontal branch is nearly constant around the circumpolar belt the front labels are also nearly constant in time the bands of enhanced ssh gradient i e fronts occur along the same streamlines throughout the 15 year period of observations both short and long period changes of the ssh frontal labels of the acc are small based on a tight relationship between dynamic height and cumulative baroclinic transport of the acc the baroclinic transport variability of the individual branches of the acc is also expected to be small the major change in the total acc baroclinic transport occurs in the drake passage the streamline associated with the northern branch of the saf saf n does not pass through drake passage and the waters carried by this branch are not observed there instead the transport of the saf n turns north in the pacific to supply the export of water to the indian ocean north and south of australia strong eddy activity in the southeast pacific acts to dissipate the hydrographic signature of the saf n there in the atlantic the saf n reappears as the same streamline is again associated with enhanced ssh gradients to the east of the brazil malvinas confluence zone while the large changes in ssh have occurred in the southern ocean between 1992 and 2007 there are strong regional differences because the acc fronts are robustly associated with particular ssh contours the changes in ssh reflect shifts in the position of the acc fronts in the circumpolar average each of the acc fronts has shifted to the south by about 60 km the changes in ssh in the southern ocean are largely due to changes in ocean circulation rather than warming and freshening by atmospheric fluxes much larger changes in ssh are observed in some locations of the southern ocean particularly where the fronts interact with large scale topography the northern branch of the pf pf n near the kerguelen plateau is an extreme example where the pf n followed a path around the northern end of kerguelen plateau between 1992 and 1997 passed through the fawn trough after 2003 and oscillated between the two paths between 1997 and 2003

remote sensing techniques for landslide studies and hazard zonation in europe abstract an inventory is presented of researches concerning the use of remote sensing for landslide studies and hazard zonation as mainly carried out in the countries belonging to the european community an overview is given of the applicability of remote sensing in the following phases of landslide studies 1 1 detection and classification of landslides special emphasis is given to the types of imagery required at different scales of analysis 2 2 monitoring the activity of existing landslides using g p s photogrammetrical techniques and radar interferometry 3 3 analysis and prediction in space and time of slope failures the different factors required in a landslide hazard study are evaluated and the optimum remote sensing imagery for obtaining each of these factors is indicated examples are given of research work carried out in these three phases from ec countries finally an evaluation is given of the aspects of uncertainty associated with the use of remote sensing data and conclusions are given as to the incorporation of remote sensing techniques within the overall framework of techniques

landslides triggered by the 1994 northridge california earthquake abstract the 17 january 1994 northridge california earthquake m w 6 7 triggered more than 11 000 landslides over an area of about 10 000 km 2 most of the landslides were concentrated in a 1000 km 2 area that included the santa susana mountains and the mountains north of the santa clara river valley we mapped landslides triggered by the earthquake in the field and from 1 60 000 nominal scale aerial photography provided by the u s air force and taken the morning of the earthquake these mapped landslides were subsequently digitized and plotted in a gis based format most of the triggered landslides were shallow 1 to 5 m thick highly disrupted falls and slides within weakly cemented tertiary to pleistocene clastic sediment average volumes of these types of landslides were less than 1000 m 3 but many had volumes exceeding 100 000 m 3 the larger disrupted slides commonly had runout paths of more than 50 m and a few traveled as far as 200 m from the bases of steep parent slopes deeper 5 m thick rotational slumps and block slides numbered in the tens to perhaps hundreds a few of which exceeded 100 000 m 3 in volume most of these were reactivations of previously existing landslides the largest single landslide triggered by the earthquake was a rotational slump block slide having a volume of 8 10 6 m 3 analysis of the mapped landslide distribution with respect to variations in 1 landslide susceptibility and 2 strong shaking recorded by hundreds of instruments will form the basis of a seismic landslide hazard analysis of the los angeles area

evaluation of factors controlling earthquake induced landslides caused by chi chi earthquake and comparison with the northridge and loma prieta events over 10 000 landslides were triggered by the september 21 1999 chi chi earthquake a large number of these landslides have been mapped from spot images and a smaller number were described in a detailed field investigation geographic information systems gis was used to conduct a spatial characterization of the slope failures including distribution of type size slope angle bedrock geology ground motion and distance from earthquake source the most abundant landslides were shallow disaggregated rock and soil slides landslides occurred primarily in tertiary sedimentary rocks which are well known for their susceptibility to landsliding in many parts of the world landslide concentration values diminish beyond epicentral distances of 40 and 70 km from the epicenter and the surface projection of the fault plane respectively ground motion was found to be the most significant factor in triggering the shallow landslides in the chi chi earthquake overall 74 of all slope failures occurred in regions with vertical ground motions greater than 0 2g and 81 of all slope failures occurred in the region with mean horizontal peak ground accelerations pga greater than 0 15g these factors were used to compare landslides generated by the chi chi earthquake to the landslides triggered by the 1989 loma prieta earthquake and the 1994 northridge earthquake the major difference in distribution of landslides between the chi chi earthquake and the two california earthquakes was the distribution of slope angles in the chi chi earthquake 90 of the failures occurred on slopes steeper than 45 while more than 80 of failures occurred on slopes less than 50 in california apparently reflecting much steeper and tectonically more active geologic setting in taiwan

competing effects of mountain uplift and landslide erosion over earthquake cycles large earthquakes can construct mountainous topography by inducing rock uplift but also erode mountains by causing landslides observations following the 2008 wenchuan earthquake show that landslide volumes in some cases match seismically induced uplift raising questions about how the actions of individual earthquakes accumulate to build topography here we model the two dimensional surface displacement field generated over a full earthquake cycle accounting for coseismic deformation postseismic relaxation landslide erosion and erosion induced isostatic compensation we explore the related volume balance across different seismotectonic and topographic conditions and revisit the wenchuan case in this context the ratio between landslide erosion and uplift is most sensitive to parameters determining landslide volumes particularly earthquake magnitude m w seismic energy source depth and failure susceptibility as well as the seismological factor responsible for triggering landslides and is moderately sensitive to the effective elastic thickness of lithosphere t e for a specified magnitude more erosive events higher tend to occur at shallower depth in thicker t e lithosphere and in steeper more landslide prone landscapes for given landscape and seismotectonic conditions the volumes of both landslides and uplift to first order positively scale with mw and seismic moment m o however higher m w earthquakes generate lower landslide and uplift volumes per unit m o suggesting lower efficiency in the use of seismic energy to drive topographic change with our model we calculate the long term average seismic volume balance for the eastern tibetan region and find that the net topographic effect of earthquakes in this region tends to be constructive rather than erosive overall destructive events are rare when considering processes over the full earthquake cycle although they are more likely if only considering the coseismic volume budget as was the case for the 2008 wenchuan earthquake where landsliding substantially offset coseismic uplift irrespective of the net budget our results suggest that the erosive power of earthquakes plays an important role in mountain belt evolution including by influencing structures and spatial patterns of deformation for example affecting the wavelength of topography

classification of large scale landslides induced by the 2008 wenchuan earthquake china over 30 000 landslides were triggered by the 2008 wenchuan earthquake the deformation and failure mechanisms of these landslides have been found distinct from those of general landslides self weight induced under gravity typical sliding in rock slope commonly occurs along a gentle tension crack in some depth at the rear part which connects to a shear plane at the lower part of the slope to form a complete failure surface however due to seismic shaking a much deeper and steeper tension crack tends to develop at the rear part which promotes the shearing at the far lower part of the slope in this paper the failure modes of earthquake induced landslides have been classified into four scenarios in terms of failure mechanisms characteristics of geological structures and development of the sliding surface i e tension strike slipping tension dip layering tension shattering and tension shearing failures this is evidenced by field investigations detailed field investigations were performed on the deformation and failure characteristics of large scale and deep seated landslides induced by the wenchuan earthquake among which five typical landslides are introduced in this paper in order to illustrate the classification

spatial and temporal analyses of post seismic landslide changes near the epicentre of the wenchuan earthquake abstract major earthquakes in mountain regions have persistent and significant influences on post seismic landslides but their details have not been well understood this work uses multi year high resolution satellite images and terrain parameters such as elevation slope and aspect to examine the topographic changes of post seismic landslides despite disturbances during rainy months landslide areas decreased significantly from 2008 to 2013 in all terrain parameters indicating that landslide activity near the epicentre has been recovering to the pre seismic level the emergence of an increasingly active landslide type shows that landslide debris has been moving from hillslopes to valleys which could impact post seismic debris flows the findings of this work provide important information for post seismic infrastructure re construction and disaster prevention in future mountain earthquake events

declining geohazard activity with vegetation recovery during first ten years after the 2008 wenchuan earthquake abstract understanding the evolution of post seismic geohazards with vegetation recovery is of great significance for long term geohazard risk assessment the wenchuan earthquake in 2008 triggered numerous landslides and severely damaged the vegetation in the earthquake stricken region between 2008 and 2017 we evaluated the vegetation recovery process the evolution of rain induced landslides and debris flows and the relationship between them by analyzing satellite images and conducting detailed field investigations shortly after the earthquake numerous landslides and debris flows were triggered by rainstorms and the vegetation was severely damaged near the epicenter in the first 5 years 2008 2013 the vegetation recovered quickly but was not well rehabilitated rain induced landslides and debris flows occurred actively but exhibited a clear declining trend in both frequency and magnitude after 2013 the vegetation gradually recovered to the pre seismic normal level in terms of quantity but with higher variability and isolated spots to be further rehabilitated over this period rain induced geohazards mainly occurred in the catchments where the level of vegetation recovery was uneven with occasional bare deposits therefore a close relation is observed between declining rain induced geohazards and the recovery of vegetation in both time and space the findings provide important information for post seismic infrastructure re construction and disaster risk reduction in future mountain earthquake events

connectivity of earthquake triggered landslides with the fluvial network implications for landslide sediment transport after the 2008 wenchuan earthquake evaluating the influence of earthquakes on erosion landscape evolution and sediment related hazards requires understanding fluvial transport of material liberated in earthquake triggered landslides the location of landslides relative to river channels is expected to play an important role in postearthquake sediment dynamics in this study we assess the position of landslides triggered by the mw 7 9 wenchuan earthquake aiming to understand the relationship between landslides and the fluvial network of the steep longmen shan mountain range combining a landslide inventory map and geomorphic analysis we quantify landslide channel connectivity in terms of the number of landslides landslide area and landslide volume estimated from scaling relationships we observe a strong spatial variability in landslide channel connectivity with volumetric connectivity ranging from 20 to 90 for different catchments this variability is linked to topographic effects that set local channel densities seismic effects including seismogenic faulting that regulate landslide size and substrate effects that may influence both channelization and landslide size altogether we estimate that the volume of landslides connected to channels comprises 43 9 7 of the total coseismic landslide volume following the wenchuan earthquake fine grained 90 of the total landslide volume may be more significantly affected by landslide locations

regional seismic slope assessment improvements considering slope aspect and vertical ground motion abstract seismic slope stability assessments in active fault zones are very important prior to designing and constructing large engineering structures however in most previous regional scale analyses ground motion records are either used directly or replaced by empirical regression equations in this paper we present an improved regional seismic slope stability assessment method considering the vertical slope aspect and ground motion based on limit equilibrium models and finite element models best fit equations are obtained to calculate the sliding angle and factor of safety fos then a two stage integration process is applied to obtain the permanent displacement the new model has been tested in the chenghai active fault zone china under a seismic precautionary intensity of 9 and the results of the new model are compared with those of traditional infinite slope models the results show that ignoring the vertical ground motion and slope aspect leads to underestimation of co seismic landslide hazards on regional scales and the new model provides a more accurate index to evaluate co seismic slope behaviours in large areas

bathymetric prediction from dense satellite altimetry and sparse shipboard bathymetry the southern oceans south of 30 s are densely covered with satellite derived gravity data track spacing 2 4 km and sparsely covered with shipboard depth soundings hundreds of kilometers between tracks in some areas flexural isostatic compensation theory suggests that bathymetry and downward continued gravity data may show linear correlation in a band of wave lengths 15 160 km if sediment cover is thin and seafloor relief is moderate at shorter wave lengths the gravity field is insensitive to seafloor topography because of upward continuation from the seafloor to the sea surface at longer wavelengths isostatic compensation cancels out most of the gravity field due to the seafloor topography we combine this theory with wiener optimization theory and empirical evidence for gravity noise to signal ratios to design low pass and band pass filters to use in predicting bathymetry from gravity the prediction combines long wavelengths 160 km from low pass filtered soundings with an intermediate wavelength solution obtained from multiplying downward continued band pass filtered 15 160 km gravity data by a scaling factor s s is empirically determined from the correlation between gravity data and existing soundings in the 15 160 km band by robust regression and varies at long wave lengths we find that areas with less than 200 m of sediment cover show correlation between gravity and bathymetry significant at the 99 level and s may be related to the density of seafloor materials in these areas the prediction has a horizontal resolution limit of 5 10 km in position and is within 100 m of actual soundings at 50 of grid points and within 240 m at 80 of these in areas of very rugged topography the prediction underestimates the peak amplitudes of seafloor features images of the prediction reveal many tectonic features not seen on any existing bathymetrie charts because the prediction relies on the gravity field at wavelengths 160 km it is insensitive to errors in the navigation of sounding lines but also cannot completely reproduce them therefore it may be used to locate tectonic features but should not be used to assess hazards to navigation the prediction is available from the national geophysical data center in both digital and printed form

monitoring activity at the daguangbao mega landslide china using sentinel 1 tops time series interferometry abstract the daguangbao mega landslide china induced by the 2008 wenchuan earthquake m w 7 9 with an area of approximately 8 km 2 is one of the largest landslides in the world experts predicted that the potential risk and instability of the landslide might remain for many decades or even longer monitoring the activity of such a large landslide is hence critical terrain observation by progressive scans tops mode from the sentinel 1 satellite provides us with up to date high quality synthetic aperture radar sar images over a wide ground coverage 250 250 km enabling full exploitation of various insar applications however the tops mode introduces azimuth dependent doppler variations to radar signals which requires an additional processing step especially for sar interferometry sentinel 1 tops data have been widely applied to earthquakes but the performance of tops data based time series analysis requires further exploitation in this study sentinel 1 tops data were employed to investigate landslide post seismic activities for the first time to deal with the azimuth dependent doppler variations a processing chain of tops time series interferometry approach was developed since the daguangbao landslide is as a result of the collapse of a whole mountain caused by the 2008 mw 7 9 wenchuan earthquake the existing digital elevation models dems e g srtm and aster exhibit height differences of up to approximately 500 m tandem x images acquired after the earthquake were used to generate a high resolution post seismic dem the high gradient topographic errors of the srtm dem i e the differences between the pre seismic srtm and the actual post seismic elevation together with low coherence in mountainous areas make it difficult to derive a precise dem using the traditional insar processing procedure a re flattening iterative method was hence developed to generate a precise tandem x dem in this study the volume of the coseismic daguangbao landslide was estimated to be of 1 189 0 110 10 9 m 3 by comparing the postseismic tandem x dem with the preseismic srtm dem which is consistent with the engineering geological survey result the time series results from sentinel 1 show that some sectors of the daguangbao landslide are still active and displaying four sliding zones and exhibiting a maximum displacement rate of 8 cm year even eight years after the wenchuan earthquake the good performance of tops in this time series analysis indicates that up to date high quality tops data with spatiotemporal baselines offer significant potential in terms of future insar applications

a review of the 2005 kashmir earthquake induced landslides from a remote sensing prospective abstract the 8th october 2005 kashmir earthquake in northern pakistan has triggered thousands of landslides which was the second major factor in the destruction of the build up environment after earthquake induced ground shaking subsequent to the earthquake several researchers from home and abroad applied a variety of remote sensing techniques supported with field observations to develop inventories of the earthquake triggered landslides analyzed their spatial distribution and subsequently developed landslide susceptibility maps earthquake causative fault rupture geology anthropogenic activities and remote sensing derived topographic attributes were observed to have major influence on the spatial distribution of landslides these were subsequently used to develop a landslide susceptibility map thereby demarcating the areas prone to landsliding temporal studies monitoring the earthquake induced landslides shows that the earthquake induced landslides are stabilized contrary to earlier belief directly after the earthquake the biggest landslide induced dam as a result of the massive hattian bala landslide is still posing a threat to the surrounding communities it is observed that remote sensing data is effectively and efficiently used to assess the landslides triggered by the kashmir earthquake however there is still a need of more research to understand the mechanism of intensity and distribution of landslides and their continuous monitoring using remote sensing data at a regional scale this paper provides an overview of remote sensing and gis applications for the kashmir earthquake triggered landslides derived outputs and discusses the lessons learnt advantages limitations and recommendations for future research

dynamic response of rock slopes to oblique incident sv waves abstract most dynamic response analyses of rock slopes only consider the vertical incidence of seismic waves however obliquely incident waves dominate in near field seismic areas this paper presents a new seismic input method that considers near field oblique incidence based on mechanisms of artificial viscous boundaries and the influence of incident angle on the dynamic response of rock slopes three numerical model slopes with different slope angles of 30 45 and 60 are excited with the el centro earthquake record assuming varying incident angles from 0 to 90 the results show that the incident angle significantly affects the dynamic response of the slopes the most damaging incident directions are approximately perpendicular to the slope surface rather than in the vertical direction the dynamic response of the slopes will be underestimated if only the vertical incidence is considered the incident angle affects the reflection wave field in the slope and the areas affected by the reflection waves decrease with increasing slope angle however the predominant period of the response spectrum of the rock slopes is not sensitive to the incident angle and location this study unveils the dynamic mechanism of earthquake induced rock slides which is of significance for earthquake hazard prevention

impacts of the chi chi earthquake on subsequent rainfall induced landslides in central taiwan abstract the influence of the chi chi earthquake on subsequent rainfall induced landslides was evaluated by comparing the occurrence of landslides in the choushui river watershed through eight spot images that covered the period from 1996 to 2001 the chi chi earthquake not only triggered serious coseismic landslides itself but also extensively disturbed surface strata around the epicentral area after surface strata have been highly disturbed heavy rainfalls in 2000 and 2001 have triggered more landslides than the earthquake itself compared with the data obtained from images before the earthquake it is obvious that the density of rainfall induced landslides increased significantly after the earthquake and the places where landslides occurred changed as well although typhoon herb in 1996 brought more precipitation than typhoon toraji in 2001 only 9 77 km 2 landslides were induced by herb while 48 8 km 2 landslides almost five times larger than those caused by herb were triggered by toraji besides landslides induced by herb were mainly distributed in mid slope areas with slopes of 20 30 after the chi chi earthquake the rainfall induced landslides occurred mainly in places with slopes between 40 and 50

a large landslide triggered by the 2008 wenchuan m8 0 earthquake in donghekou area phenomena and mechanisms abstract during the 2008 wenchuan earthquake more than 60 000 landslides were triggered resulting in about 20 000 casualties among these landslides a catastrophic one occurred in donghekou area of qingchuan county donghekou landslide had a volume of about 1 107 m3 traveled fast for approximately 2 km killing about 780 people the source area consisted of unstable sedimentary strata and the runout path was made of colluvial deposits during the earthquake the colluvial deposits started to move first before the arrival of the displaced landslide debris from the main source area we performed undrained cyclic ring shear tests on samples taken from the runout path and concluded that liquefaction of the runout path material enhanced the mobility of the debris material a fumarole was identified on the upper part of the runout path 6 months later we analyzed the gas and water venting out and concluded that the fumarole was not the result of fault movement it resulted instead from the weathering of slate from the source area the long travel landslide materials blocked two rivers forming two landslide dams that breached with the occurrence of overtopping to better understand the internal structure of the landslide deposits and then provide evidence for a rational plan of countermeasures to stabilize the landslide dams we measured the shear wave velocity of the landslide deposits by a surface wave technique called multichannel analysis of surface waves masw the results revealed that the landslide dams consisted of loosely deposited debris suggesting that the landslide dams were mechanically weak and prone to erosion by overtopping

long term trends and interannual variability of temperature in drake passage abstract temperature data collected over the last 36 years 1969 2004 in drake passage are used to examine interannual temperature variation and long term trends in the upper ocean to reduce the effect of variation from different sampling locations and temporal variability introduced by meridional shifts in the polar front pf the data were divided into two sub regions north 3800 temperature profiles and south 3400 of the pf temperature anomalies were formed by removing a temporal mean field for each profile in each sub region at 100 m depth intervals from the surface to 700 m north of the pf statistically significant warming trends of 0 02 c yr 1 were observed that were largely depth independent between 100 and 700 m a statistically significant cooling trend of 0 07 c yr 1 was observed at the surface south of the pf which was smaller 0 04 c yr 1 but still statistically significant when possible seasonal sampling biases were accounted for the observed cooling at the surface and warming at depth is largely consistent with a poleward shift of the pf due to enhancement of westerly winds in the southern ocean as recently suggested by models and observations the observed annual temperature anomalies in the upper 400 m north of the pf and in the upper 100 m south of the pf are highly correlated to variability in sea ice and also to climate indices of the antarctic oscillation and the el nino southern oscillation variability in sea ice and temperature anomalies lag el nino variability in the pacific with a phasing consistent with the observed cyclical patterns of sea ice and sea surface temperature associated with the antarctic circumpolar wave or antarctic dipole mode in the southern ocean in contrast the sea ice variability and temperature anomalies at all depths north of the pf and at 0 100 m depth south of the pf were primarily coincident with or led the antarctic oscillation index no significant correlations were found with the large scale climate variability indices in southern drake passage below 100 m depth which is occupied by upper circumpolar deep water ucdw this water mass is not formed locally is largely isolated from the surface and exhibits vertical and lateral homogeneity hence changes may be difficult to detect in the available measurements and climate variation in the source water regions of ucdw may take a long time to reach drake passage

a circumpolar gravest empirical mode for the southern ocean hydrography historical hydrographic data from the southern ocean are projected into a baroclinic stream function space generating a three dimensional gravest empirical mode gem parameterized by pressure geopotential height and longitude the low dimensional gem projection is intrinsically steady vertically coherent and equivalent barotropic the gem fields capture more than 97 of the total density and temperature variance in the antarctic circumpolar current region

evolution of debris flow activities in gaojiagou ravine during 2008 2016 after the wenchuan earthquake abstract the 2008 wenchuan earthquake in sichuan china triggered numerous landslides in the stricken area the loose landslide materials retained on mountain slopes and in gullies are prone to reactivation and may transform into debris flows in the rainy season nine years after the wenchuan earthquake debris flows are still active in gaojiagou ravine 16 5 km north of the epicentre on 14 august 2010 3 july 2011 13 july 2013 and 6 july 2016 four large scale debris flows were triggered by heavy storms in gaojiagou ravine the four debris flows blocked the minjiang river twice and caused severe damage to nearby villages and reconstruction sites several questions arise from these repeated debris flows did the level of triggering rainfall change in the four debris flow events how did the initiation mechanism evolve over time what are the differences in the runout characteristics in the four events how did the check dams constructed in 2012 function in the subsequent debris flows in this paper we evaluated the loose deposit volumes in gaojiagou ravine before and after each of the four debris flows and the runout volumes and analysed the triggering rainfall intensities initiation mechanisms and runout characteristics of the four debris flows the rainfall threshold for the debris flows in gaojiagou ravine increased over time and the initiation mechanisms evolved from landslides to channel bed failure and subsequently to channel bank erosion the mobility of the debris flows decreased from 2010 to 2016 as the initiation positions moved lower and the particle size of the runout materials became coarser

decadal spinup of the south pacific subtropical gyre abstract an increase in the circulation of the south pacific ocean subtropical gyre extending from the sea surface to middepth is observed over 12 years datasets used to quantify the decadal gyre spinup include satellite altimetric height the world ocean circulation experiment woce hydrographic and float survey of the south pacific a repeated hydrographic transect along 170 w and profiling float data from the global argo array the signal in sea surface height is a 12 cm increase between 1993 and 2004 on large spatial scale centered at about 40 s 170 w the subsurface datasets show that this signal is predominantly due to density variations in the water column that is to deepening of isopycnal surfaces extending to depths of at least 1800 m the maximum increase in dynamic height is collocated with the deep center of the subtropical gyre and the signal represents an increase in the total counterclockwise geostrophic circulation of the gyre by at least 20 at 1000 m a comparison of woce and

analysis of physical testing of rainfall induced soil slope failures rainfall is a significant factor that triggers slope failures around the world this paper reports a series of physical tests which were conducted to simulate rain induced slope failures the experiments dealt with two scenarios including 1 rainwater infiltration into the slope and 2 slope failures induced by artificial rainfall with different initial conditions slope deformation and slope failures were observed and possible mechanisms were interpreted based on the experimental results the results confirm the hypothesis that pore water pressure and water content in a loose soil slope change rapidly and that water infiltration into cracks in the slope has a great impact on landslide development the observed slope failures can be divided into three types overall sliding failure partial sliding failure and flow slide the effect of slope gradient rainfall intensity and distribution of initial suction on the slope deformation and failure process are also summarized for possible applications under the similar conditions

characteristics of earthquake and rain induced landslides near the epicenter of wenchuan earthquake abstract numerous landslides were triggered by the 12 may 2008 wenchuan earthquake in china particularly near the epicenter during the rainy season in 2010 after the earthquake much of the landslide debris was reactivated causing a large number of fatalities the earthquake has a significant impact on the subsequent rain induced landslides based on interpretation of satellite images taken in 2008 and 2010 combined with yearly field investigations this paper attempts to 1 map the earthquake induced landslides near the epicenter 2 present the distribution of the landslides occurring during a subsequent extreme storm in the same area and 3 compare the distribution characteristics of the earthquake induced landslides and the rain induced landslides through this study the following findings were obtained 1 the internal relief of the landslides in the study area is much higher than that in other affected regions of the wenchuan earthquake zone 2 the landslide area in hard rocks i e the granite and diorite zones is much larger than that in alluvium 3 the volume of hill slope loose deposits decreased while the volume of channel deposits increased during the process of mass transportation caused by rainfall after the earthquake 4 during the rainy seasons after the earthquake the density of landslides increased while the area of landslides decreased significantly and the type of landslides transformed from debris slides to debris flows and 5 the rain induced landslides are less steeper than the earthquake induced landslides

engineering measures for debris flow hazard mitigation in the wenchuan earthquake area avalanches and landslides caused by the wenchuan earthquake in the longmen mountains area provide abundant loose solids for debris flows and a large number of debris flows have occurred during the period 2008 2012 the engineering measures in certain gullies failed causing serious damage and loss of life judging from the debris flow characteristics in the wenchuan earthquake area engineering measures should be better constructed after the active period of debris flows in severely affected areas to reduce debris flow disasters this paper proposes a mitigation method and design principle based on the transport capacity of the main river a series of check dams with various opening sizes was designed by investigating and analyzing existing cases furthermore a new type of drainage channel with prefabricated reinforced concrete boxes is proposed finally a case study of the xiaogangjian gully which is a typical debris flow gully in the wenchuan earthquake area is presented this system of engineering measures is based on the main river s transport capacity and consists of five check dams with various opening sizes a drainage channel with sidewalls constructed of prefabricated reinforced concrete boxes and a debris flow basin at the base of the main gully the debris flow mitigation measures constructed in the xiaogang jian gully effectively resisted a debris flow with a 50 year return period that was triggered by rainfall on july 26 2012 specifically these measures effectively protected a highway and minimized debris flow damage thus the layout and engineered structures involved in this new engineering technique can provide a reference design for debris flow hazard mitigation c 2014 elsevier b v all rights reserved

alpine debris flows triggered by a 28 july 1999 thunderstorm in the central front range colorado on 28 july 1999 about 480 alpine debris flows were triggered by an afternoon thunderstorm along the continental divide in clear creek and summit counties in the central front range of colorado the thunderstorm produced about 43 mm of rain in 4 h 35 mm of which fell in the first 2 h several debris flows triggered by the storm impacted interstate highway 70 u s highway 6 and the arapahoe basin ski area we mapped the debris flows from color aerial photography and inspected many of them in the field three processes initiated debris flows the first process initiated 11 of the debris flows and involved the mobilization of shallow landslides in thick often well vegetated colluvium the second process which was responsible for 79 of the flows was the transport of material eroded from steep unvegetated hillslopes via a system of coalescing rills the third which has been termed the firehose effect initiated 10 of the debris flows and occurred where overland flow became concentrated in steep bedrock channels and scoured debris from talus deposits and the heads of debris fans these three processes initiated high on steep hillsides 30 in catchments with small contributing areas 8000 m2 however shallow landslides occurred on slopes that were significantly less steep than either overland flow process based on field observations and examination of soils mapping of the northern part of the study area we identified a relation between the degree of soil development and the process type that generated debris flows in general areas with greater soil development were less likely to generate runoff and therefore less likely to generate debris flows by the firehose effect or by rilling the character of the surficial cover and the spatially variable hydrologic response to intense rainfall rather than a threshold of contributing area and topographic slope appears to control the initiation process in the high alpine of the front range because debris flows initiated by rilling and the firehose effect tend to increase in volume as they travel downslope these debris flows are potentially more hazardous than those initiated by shallow landslides which tend to deposit material along their paths

a physically based distributed cell model for predicting regional rainfall induced shallow slope failures abstract rainfall induced slope failures are one of the most frequent hazards on hilly terrains this paper proposes a physically based distributed cell model to predict regional rainfall induced shallow slope failures in two layer soils under realistic rainfall conditions the model consists of four components namely a digital terrain model a spatial rainfall distribution model an infiltration analysis model and a slope stability and reliability evaluation model the digital terrain is discretized into a grid of numerous cells first with the properties of the soils in each cell assigned universal kriging is then adopted to interpolate the spatial rainfall distribution afterwards the infiltration analysis model is used to analyze the infiltration process in two layer soils under realistic rainfall conditions the slope stability and reliability evaluation model is finally adopted to assess the regional slope stability and reliability the distributed cell model is applied to evaluate the spatial and temporal response of a 164 5 km2 area to rainfall near the epicenter of the 2008 wenchuan earthquake zone comparison between the predicted and observed slope failures triggered by the 13 august 2010 storm shows that this model is capable of predicting the locations of rainfall induced slope failures reasonably well the model is intended for use as a module in a real time warning system for rainfall induced slope failures

evaluating volume of coseismic landslide clusters by flow direction based partitioning abstract a strong earthquake can trigger thousands of co seismic landslides the evaluation of the volume of such co seismic landslides is essential for landslide risk assessment and long term post earthquake hazard evaluation empirical volume area power laws are often applied to estimate the landslide volume when several small landslide deposits form a large cluster on the hillslope blurry boundaries of the clustered co seismic landslides may lead to seemingly one large landslide and grossly overestimated landslide volume in this paper we propose a flow direction based method to identify the boundaries of a cluster of landslides and to partition co seismic landslides three watersheds that were severely impacted by co seismic landslides in the wenchuan earthquake region are chosen for case studies each co seismic landslide cluster in these watersheds was interpreted from images taken shortly after the earthquake and partitioned into individual landslides in accordance with a flow direction map that is processed based on a local digital terrain model finally the volume of each individual landslide is calculated using an empirical volume area power law the adopted power law scaling relationship is selected from six widely used empirical relations and verified by 11 local landslide cases the proposed flow direction based partitioning method is further verified by clear boundaries of landslides that were exposed after storms as well as supplementary field survey results the proposed method results in similar landslide boundaries and volumes as the field survey results the uncertainty of this approach is below 19 if no partitioning is conducted the total volume of the landslide cluster can approach twice that from the field investigations

multidecadal warming of subsurface temperature in the indian sector of the southern ocean 1 long term variations of subsurface layer temperature were examined for 32 years 1966 1998 of continuous observations in the indian sector of the southern ocean the data analyzed consist of observations from japanese antarctic research expeditions and also from other countries significant warming trends of about 0 004 c yr 1 were observed at all depths from 200 to 900 m to the north of the southern antarctic circumpolar current acc front orsi et al 1995 the rates of warming increase with increasing depth from 0 003 c yr 1 at 200 m to 0 012 c yr 1 statistically significant at 900 m in the region close to the front these warming trends were also found after applying a technique to correct for differences in the data sampling locations the warming tendency in the frontal region is consistent with the assumption of a southward shift of the front and may have a relationship with the observed retreat of sea ice edge

dda validation of the mobility of earthquake induced landslides abstract this paper studies the run out of earthquake induced landslides there are more than 20 mechanical models to explain long run out of rapid landslides including some earthquake induced landslides however notably few of them considered the effect of seismic loading on the run out of landslides in a previous study we have proposed a model which is called the multiplex acceleration model mam to interpret the long run out mechanism and a shaking table test has been performed to verify the mam because the previous mam is a conceptual model and only a single stone has been examined under sine waves by the shaking table test the mam needs to be extended and further verified in this paper the mam was extended by introducing the movement change that was induced by the so called trampoline effect of earthquake loading and the latest practical numerical simulation program discontinuous deformation analysis dda was used to verify the mobility of earthquake induced landslides after a conceptual landslide model was used to verify the effect of seismic loading on the mobility the donghekou landslide which was a typical long run out landslide that was induced by the 2008 wenchuan earthquake was analyzed the results show that the seismic loading could be one of the factors that could eventually help increase the run out of landslides

evolution of debris flow properties and physical interactions in debris flow mixtures in the wenchuan earthquake zone abstract the 2008 wenchuan earthquake triggered an exceptional number of landslides the large amount of loose landslide materials on the steep terrains can easily turn into debris flows by heavy rainfall during the wet seasons from 2008 to 2011 five destructive debris flows occurred repeatedly in yingxiu the study area near the epicenter this paper presents the evolution of debris flow properties and physical interactions in the debris flow mixtures in the past few years seven dimensionless numbers are used to describe the physical interactions the evolution of the physical interactions over time was influenced by changes in debris flow compositions which in turn affected the runout characteristics of the debris flows significantly grain contact friction was the most important physical interaction for the five debris flows in the study area with gradual loss of fine particles over time the viscosity of the debris flow mixtures became lower and lower leading to a change from the dominance of viscous shear over solid fluid interactions and inertial grain collision to the dominance of solid fluid interactions and inertial grain collision over viscous shear with inertial grain collision being more and more important the flow resistance of the debris flows increased the mobility of the future debris flows may become smaller and smaller

stability analysis of rock wedge slide subjected to groundwater dynamic evolution abstract heavy rainfall may increase the infiltration rate raising the groundwater table after a short period time variation in the hydrostatic pressure on potential sliding surfaces and trailing edges of fissures in a rock slope may contribute to slope failure the failure mechanisms of rainfall triggered rock wedge slides have been widely studied in the literature however studies on the dynamic evolution of groundwater in rock failure are still limited in this study a typical rock wedge slide that occurred in chengkou county chongqing china is selected as a case study to analyze the stability of rock wedge with double planes and tension crack subjected to groundwater dynamic evolution model tests were designed and performed to reproduce the dynamic evolution of groundwater in the rock slope and analyze its role in wedge failure development and distribution characteristics of water pressure are investigated through monitoring the water pressure distributed along the surfaces of wedge failures from the experimental study it is found that the initial formation process of water pressure along the sliding surface consists of four types of distribution patterns i e triangular distribution type i trapezoidal distribution type ii trapezoidal distribution and type iii trapezoidal distribution based on the model tests and theoretical analysis the order of the calculated safety factors of the chengkou rock wedge slide are triangle type i trapezoid type ii trapezoid type iii trapezoid the existence of inflection points in the trapezoidal distribution mode significantly increases water pressure on both sides of rock wedge which contributes instability the new approach for investigation of the effect of dynamic evolution groundwater on stability of rock wedge slide is developed based on fundamental mechanism and experimental study it can be adopted for stability assessment of similar rock wedge slides in other areas