morphology and inner structure of luanshibao rock avalanche in litang china and its implications for long runout mechanisms abstract large rock avalanches usually move rapidly and travel long distances making them extremely hazardous and often result in catastrophic damages the currently proposed hypotheses for the mechanisms causing their high mobility remain controversial petley 2013 the luanshibao ancient granite rock avalanche with a 10be exposure age of 3510 346 years b p and a deposit volume of 67 mm3 straddles on the litang active fault and was deposited on an open flat river terrace without confinement it travelled about 4000 m with an apparent coefficient of friction of 0 22 field investigation interpretation of satellite images and study of the morphology and inner structure of its deposit were used to analyze its kinetics and dynamics and its long runout mechanisms the study showed that there was probably a two stage movement transition from rock slope collapsing to debris spreading based on the remarkable high secondary scarps and a long belt of bare blocks the runout is closely related to the volume detached from the secondary scarp three different kinds of deposit morphologies were recognized i e parallel transverse ridge grooves x grooves and rhombic platforms and round elliptical hummocks from the proximal to the distal end indicating the strain response to stresses in the debris in motion due to compression shear and tension respectively these deposit morphologies as well as the inner structures such as homogeneous layers of blocks inner shear belts and jigsaw fractured blocks suggested that the extra runout debris moved as a pattern of laminar flow or as a flow sheet however the strong mixing of fluvial pebbles and avalanche debris in the distal hummocky zone suggested a pattern of turbulent flow the possible liquefaction of saturated fluvial sediments by a triggering strong earthquake the extra pore pressure generated by the high speed undrained shearing of debris in the substrate and the entrainment of a large amount of quaternary sediment could have contributed to the great reduction of friction of the basal layer the particle size decreasing with distance away from the secondary scarps and the disintegration of jigsaw structures suggest that rock fragmentation occurred during motion this implies that the long runout of the rock avalanche resulted from many factors

complete dynamic modeling calibration for the thurwieser rock avalanche italian central alps abstract few rock avalanches have been witnessed and no exact real time description is available the 2 5 m m 3 punta thurwieser rock avalanche september 2004 italian central alps is a unique event for which many quantitative observations have been gathered this is the first case ever of a natural rock avalanche being recorded on video and for which an almost exact value of the total time duration from initial detachment to final deposition is available the landslide travelled over 2 9 km from its source partially in a glacial environment the initial failure and the time for the complete evacuation of the source area were studied and assessed by a series of photos the mean front velocities along the path have been estimated from the video the final geometry and the characteristics of the deposit have been obtained by gps measurements aerial photos field surveys and laboratory tests a quasi 3d continuum dynamic analysis of the landslide motion has been performed assuming both a voellmy and a frictional rheology in the model dan 3d for the first time the landslide front velocities have been used for back analyses and calibration of the rheological parameters together with the final shape and thickness of the deposit and its developing extension the dynamic flow resistance parameters initially calibrated with dan were adopted and validated in dan 3d showing good consistency they are consistent with the existing database for calibrated landslides of similar type and scale flow velocities on the path segment underlain by glacial deposits up to 55 65 m s 1 are more accurately predicted by adopting a frictional rheology up to 50 55 m s 1 with zero pore pressure and a 26 friction angle than by a voellmy rheology up to 40 45 m s 1 both observations and modelling show that glacial ice plays a substantial role in increasing the rock avalanche mobility

topographical changes revealed by high resolution airborne lidar data the 1999 tsaoling landslide induced by the chi chi earthquake abstract the 1999 chi chi earthquake triggered the catastrophic tsaoling landslide in central taiwan we mapped the landslide area and estimated the landslide volume using a high resolution digital elevation model from airborne lidar light detection and ranging aerial photographs and topographic maps the comparison between scar and deposit volumes about 0 126 km3 and 0 150 km3 respectively suggests a coseismic volume increase of 19 due to decompaction during landsliding in july 2003 the scar and deposit volumes were about 0 125 km3 and 0 110 km3 respectively these estimates suggest that 4 years after the event the volume of landslide debris removed by river erosion was nearly 0 040 km3 these determinations are confirmed by direct comparison between the most accurate topographic models of the post landslide period indicating a very high erosion rate at the local scale 0 01 km3 year for the deposit area of the landslide such a large value highlights the importance of landslide processes for erosion and long term denudation in the taiwan mountain belt

laboratory analogue of the formation of molards cones of rock avalanche debris debris cones or molards occur on the deposits of rockslide avalanches they are a few metres high conical in shape and contain material finer than the surrounding debris previously proposed formation mechanisms of molards were tested against field evidence from the frank slide and are found to be unsatisfactory laboratory experiments indicate that when a mass of cohesion less soil is vibrated particle formed molards therefore may form by vibration of the ground under rockslide avalanches this formation mechanism may bear on the problem of rockslide avalanche mobility

miocene jiali faulting and its implications for tibetan tectonic evolution the karakoram jiali fault zone kjfz comprises a series of right lateral shear zones that southerly bound the eastward extrusion of northern tibet relative to india and stable eurasia here we present new 40 ar 39 ar age data from the puqu and parlung faults two easternmost branches of the jiali fault zone which indicate a main phase of the kjfz shearing from v18 to 12 ma thus the tibetan eastward extrusion bounded by principal strike slip fault zones started and was probably most active around the middle miocene an interval marked also by active east west extension in southern tibet the coincidence of these two tectonic events strongly suggests a common causal mechanism which is best explained as oblique convergence between india and asia under the framework of this mechanism the extension in southern tibet is not a proxy for the plateau uplift the kjfz activity was furthermore coincident with right lateral displacements along the gaoligong and sagaing faults in southeast asia this defines a miocene deformation record for the regional dextral accommodation zone that in response to the continuing india asia collision may have accounted for the initiation and prolonged history of clockwise rotation of the tibetan extrusion around the eastern himalayan syntaxis 2002 elsevier science b v all rights reserved

draining the tangjiashan barrier lake this paper documents the emergency breaching of an approximately 110 m high landslide dam that was created at tangjiashan during the 2008 wenchuan earthquake of china s southwest sichuan province as an emergency measure a 13 m deep channel was excavated to reduce the volume and head of the released water during the dam breaching and to create a controlled flood that was intended to prevent catastrophic consequence for 1 2 million people downstream from detailed monitoring and survey works carried out during and after the dam break it was found that 1 the breaching initiated at a pool water level of 742 1 m with an estimated flow velocity of 2 4 m s and virtually terminated at a pool water level of 720 3 m with an estimated velocity of 2 5 m s which can be regarded as the incipient velocity that initiated erosions for the soils at this particular site 2 a controlled flood released 167 106 m3 reservoir water with a peak flow rate of 6 500 m3 s during which a maximum velocity of about 5 0 m s

dynamics of the 1984 rock avalanche and associated distal debris flow on mount cayley british columbia canada implications for landslide hazard assessment on dissected volcanoes abstract in 1984 a mass of quaternary pyroclastic rock est vol 0 74 106m3 slid from the western flank of mount cayley volcano in southwest british columbia the disintegrating rock mass entrained a further 0 20 106 m3 and formed a rock avalanche that travelled a horizontal distance of 3 46 km from its source over a vertical elevation difference of 1 18 km equivalent to a fahrboschung of 19 from the superelevation of the debris trimline in the mid path it is estimated that velocities reached at least 42 m s in the upper part of its path velocities may have approached 70 m s the rock avalanche was partially transformed into a distal debris flow that travelled a further 2 6 km down turbid creek in a narrow channelised path to the squamish river temporarily blocking it the motion of the rock avalanche including the production of a distal debris flow was successfully simulated using a dynamic analytical model both the results of this analysis and field evidence indicate that the rock avalanche did not come to a halt in the upper part of its path as suggested by cruden and lu 1992 but travelled to its distal limit in one uninterrupted movement this finding has important implications for landslide hazard assessment at mount cayley and similar sites the landslide is typical of those which occur on the steep slopes of dissected volcanoes and is one of seven high velocity rock avalanches that have occurred in the garibaldi volcanic belt of southwest british columbia since 1855

the tsergo ri landslide an uncommon area of high morphological activity in the langthang valley nepal abstract the large scale mass movement of tsergo ri langthang valley central north nepal was investigated from the viewpoint of morphological activity for the first time the quaternary mass movement fission track age about 4 10 4 yr only affected crystalline hard rocks gneisses migmatites and leucogranites of a dimension of 10 10 m 3 during the mass displacement an extreme shattering of the rocks happened which is mainly responsible for the high actual morphological activity in the tsergo ri landslide deposit area three different zones of highest morphological activity the sum of the presently occurring geomorphic processes can be distinguished 1 a high very steep slopes mainly in bedrock show usual morphological activity except when they were affected by the landslide event e g the barrier where the sliding mass crashed against e slope of pangshungtramo peak 2 b slopes and erosional channels underneath glaciated or perennial firn areas or areas which are snow covered most of the year show a permanent or seasonal morphological activity e g the area in front of the yala tsang 3 c the zone with the biggest extension of actual morphological activity is the area of the tsergo ri landslide deposit with intense rock shattering of the sliding mass e g the dranglung valley or the s and sw slopes of tsergo ri zones a and b come up to the noral expectations of morphological activity for high mountain regions zone c makes the whole tsergo ri landslide deposit area an outstanding terrain of the upper langthang valley with extremely high morphological activity

glaciers and mass wasting processes their influence on the shaping of the kali gandaki valley higher himalaya of nepal abstract this paper addresses the question of the respective role of glaciers and mass wasting processes in the shaping of the high valleys of the central himalaya this is a region in which the himalayan range is at its narrowest and where it is cut by the deepest gorge in the world the kali gandaki valley following a brief description of the region and of the criteria used to discriminate between both sets of processes some specific sites that have given rise to divergent interpretations are discussed it is shown that undoubted evidence of past glaciation is rare and that most of the diamictons observed today are best interpreted as the products of deep seated landslides and or catastrophic debris flows of large magnitude and probably low frequency spanning the period from the last glacial maximum to the holocene the modalities of this evolution cast some doubt on some former reconstructions of past glacial extents moreover the continuous reworking of this material continues to influence the nature and current rates of erosion

isostatic uplift driven by karstification and sea level oscillation modeling landscape evolution in north florida isostatic uplift of tectonically stable passive margin lithosphere can preserve a record of paleo shoreline position by elevating coastal geomorphic features above the influence of nearshore wave activity conversely depositional ages and modern elevations of these features can provide valuable information about the uplift history of a region we present a numerical model that combines sea level oscillation subaerial exposure a precipitation karstification function and isostatic uplift to explore the dynamic geomorphic behavior of coastal carbonate landscapes over multiple sea level cycles the model is used to estimate ages of coastal highstand depositional features along the atlantic coast of north florida numerical simulations using current best estimates for pleistocene sea level and precipitation histories suggest ages for trail ridge 1 44 ma the penholoway terrace 408 ka and the talbot terrace 120 ka that are in agreement with fossil evidence in addition model results indicate that the rate of karstification void space creation or equivalent surface lowering rate within the north florida platform is 3 5 times that of previous estimates 1 m 11 2 k y vs 1 m 38 k y and uplift rate is 2 times as high as previously thought 0 047 mm yr vs 0 024 mm yr this process has implications for landscape evolution in other carbonate settings and may play an underappreciated role within the global carbon cycle

chronology and tectonic significance of cenozoic faults in the liupanshan arcuate tectonic belt at the northeastern margin of the qinghai tibet plateau abstract the liupanshan arcuate tectonic belt latb is located at the northeastern margin of the qinghai tibet plateau major strike slip and thrust faults in the liupanshan area are prominent cenozoic structures which are critical in understanding and reconstructing the tectonic deformation history this paper not only provides detailed investigations on geometric and kinematic characteristics of these faults in the latb but also dates the faults movements by electron spin resonance esr the latb underwent a succession of compression extension and again compression tectonic deformation processes since the cenozoic the liupanshan curved faults first experienced sinistral strike slip shear during 57 61 ma the liupanshan curved faults responded to the deformation caused by the eastward escape of the qinghai tibet plateau and acted as the northeastern boundary of the deformation timing for the formation of the liupanshan curved faults shows that the collision of the indian and eurasian plates must have occurred earlier than these faults activity because the latter is reflected the far field effect of the collision

the formation and failure of natural dams of the numerous kinds of dams that form by natural processes dams formed from landslides glacial ice and late neoglacial moraines present the greatest threat to people and property landslide dams form in a wide range of physiographic settings the most common types of mass movements that form landslide dams are rock and debris avalanches rock and soil slumps and slides and mud debris and earth flows the most common initiation mechanisms for dam forming landslides are excessive rainfall and snowmelt and earthquakes landslide dams can be classified into six categories based on their relation with the valley floor type i dams 11 of 184 landslide dams from around the world that we were able to classify do not reach from one valley side to the other type ii dams 44 span the entire valley floor in some cases depositing material high on opposite valley sides type iii dams 41 move considerable distances both upstream and downstream from the landslide failure type iv dams 1 are rare and involve the contemporaneous failure of material from both sides of a valley type v dams 1 also are rare and are created when a single landslide sends multiple tongues of debris into a valley and forms two or more landslide dams in the same reach of river type vi dams 3 involve one or more failure surfaces that extend under the stream or valley and emerge on the opposite valley side many landslide dams fail shortly after formation in our sample of 73 documented landslide dam failures 27 of the landslide dams failed less than 1 day after formation and about 50 failed within 10 days over topping is by far the most common cause of failure the timing of failure and the magnitude of the resulting floods are controlled by dam size and geometry material characteristics of the blockage rate of inflow to the impoundment size and depth of the impoundment bedrock control of flow and engineering controls such as artificial spill ways diversions tunnels and planned breaching by blasting or conventional excavation glacial ice dams can produce at least nine kinds of ice dammed lakes the most dangerous are lakes formed in main valleys dammed by tributary glaciers failure can occur by erosion of a drainage tunnel under or through the ice dam or by a channel over the ice dam cold polar ice dams generally drain supraglacially or marginally by downmelting of an outlet channel warmer temperate ice dams tend to fail by sudden englacial or subglacial breaching and drainage late neoglacial moraine dammed lakes are located in steep mountain areas affected by the advances and retreats of valley glaciers in the last several centuries these late neoglacial dams pose hazards because 1 they are sufficiently young that vegetation has not stabilized their slopes 2 many dam faces are steeper than the angle of repose 3 these dams and lakes are immediately downslope from steep crevassed glaciers and near vertical rock slopes and 4 downstream from these dams are steep canyons with easily erodible materials that can be incorporated in the flow and increase flood peaks the most common reported failure mechanism is overtopping and breaching by a wave or series of waves in the lake generated by icefalls rockfalls or snow or rock avalanches melting of ice cores or frozen ground and piping and seepage are other possible failure mechanisms natural dams may cause upstream flooding as the lake rises and downstream flooding as a result of failure of the dam although data are few for the same potential energy at the dam site ownstream flood peaks from the failure of glacier ice dams are smaller than those from landslide moraine and structed earth fill and rock fill dam failures moraine dam failures appear to produce some of the largest downstream flood peaks for potential energy at the dam site greater than 1011 1012 joules differences in flood peaks natural dam failures appear to be controlled by dam characteristics and failure mechanisms

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

analysis of landslide dams induced by the 2008 wenchuan earthquake abstract landslide dams caused by earthquakes are extremely hazardous disruptions of the flow of water and sediment in mountain rivers capable of delivering large outburst floods that may devastate downstream areas we analyzed a unique inventory of 828 landslide dams triggered by the m w 7 9 2008 wenchuan tectonic earthquake china constituting 1 4 of the 60 000 coseismic slope failures mapped and attributed to this event while 501 landslides blocked the rivers completely the remainder caused only partial damming or channel diversion the spatial distribution of landslide dams follows the same trend of that of the total landslide distribution with landslide dams being most abundant in the steep watersheds of the hanging wall of the yingxiu beichuan thrust fault and in the northeastern part of the strike slip fault near qingchuan besides the co seismic landslide density the river width also played a key role in determining the landslide dam formation narrow rivers are more prone to be dammed than the wide rivers the correlation between river width and landslide dam volume follows a linear relation which can be used to roughly estimate the dam formation possibility however the applicability of this correlation needs to be validated in other regions the decay failure rate of dams defined here as the percentage of the number and area of landslide dams that have failed over time shows that 25 of dams accounting for 30 of total landslide dam area failed one week after the earthquake these percentages increased to 60 within 1 month and to 90 within 1 year the geomorphometric parameters were analyzed revealing power law relations between landslide area and dam width landslide source area and dam area as well as lake area and lake volume the inventory presented in this study will enrich the worldwide earthquake induced landslide dam database and will also contribute to a better understanding of the post earthquake dam decay

holocene landslide dammed lake deposits in the upper jinsha river se tibetan plateau and their ages in the zhongzaebatang segment of the upper jinsha river in the southeast of the tibetan plateau there are eight old landslide dams with nearby associations of relict landslides lacustrine sediments and fluvial sediments associations of this kind provide key evidence for identifying the lacustrine sediments as landslide dammed lake deposits the 14 c ages of 12 samples and the osl ages of 9 samples show that the landslide dammed lake deposits formed during a period of about 122 ade1100 ad corresponding to the time of the late donghan dynasty to the middle of the song dynasty landslides that formed the landslide dammed lake deposits are inferred to be due to earthquakes triggered by active faults

unravelling the multiphase run out conditions of a slide flow mass movement abstract in this paper an attempt is made to unravel the run out characteristics of a mass movement in the sichuan province sw china by means of 1d numerical modelling and calibration on the topography of run out profiles the dagou mass movement started as a rockslide with an initial volume of 480 000 m3 which transformed into a debris flow increasing in volume due to entrainment of loose material in the upper part of the travelling track the rapid mass movement had a run out distance of 1380 m and a run out time of about 50 s numerical calculations were conducted with the depth average shallow water equation to explain the variation in thickness of the debris flow deposits along the run out track for the calibration of the first run out phase three rheological models were applied namely the bingham voellmy and quadratic rheology calibration was done on 1 the run out distance 2 the run out time and 3 the goodness of fit with the thickness of the deposits along the track in addition the erosion constant in the entrainment equation was calibrated on the observed versus calculated run out volumes sensitivity analyses of the resistance parameters for the different rheologies showed that the viscosity the basal friction the turbulence term and the resistance factor are the most sensitive ones it appeared that the variation in thickness along the run out track can be explained by entrainment of material in the upper part of the track and a change in parametric values during the run out process the three rheologies produced a reasonable fit with the observed geometry of the run out profile run out time and run out volume it was argued that the voellmy rheology seems to give the most appropriate explanation for the difference in resistance along the run out path the main problem in the simulation was to stop the debris flow on a slope with a gradient around 22 a reactivation of the mass movement by frictional sliding of the material half way the run out track was simulated it occurred 30 min after the first run out phase due to an increase in pore pressure the sliding material changed into a slow flowing mass that reached a newly built up area after about 1 h and moved into wangong town over a distance of 80 m

how unusual is the long runout of the earthquake triggered giant luanshibao landslide tibetan plateau china abstract in the tibetan plateau active tectonic deformation triggers frequent earthquakes and giant landslides associated with active faults produce serious consequences a study of the characteristics and mechanism of a historical long runout landslide in luanshibao lsb tibetan plateau china finds a maximum sliding distance l of 3 83 km with an elevation drop h of 820 m the landslide volume v was 0 64 0 94 10 8 m 3 and it produced a long runout h l 0 21 recent surface offset along the sinistral strike slip litang dewu fault passes through the middle part of the landslide which initiated on the hanging wall of the fault geological mapping geophysical prospecting trenching and 14 c dating together indicate that the lsb landslide occurred in jointed granite ca 1980 30 ybp probably triggered by a large earthquake compilation of volume and runout distance data for this landslide and other previously published data for volcanic and nonvolcanic long runout landslides yields a composite runout length volume relation l 12 52 v 0 37 that closely predicts runout of the lsb landslide although substantial variation is noted in runout length around the central tendency

characteristics and transport mechanism of the nyixoi chongco rock avalanche on the tibetan plateau china abstract for studying rock avalanches complex surficial and internal characteristics have been regarded as important indicators for understanding avalanche transport mechanism in the present study deposits of a massive holocene rock avalanche termed the nyixoi chongco rock avalanche located on the lhasa terrane of tibetan plateau in china are investigated based on a combination of remote sensing data and in situ observations it is revealed that abundant surface landforms including toreva blocks longitudinal and transverse ridges en echelon ridges and hummocks are commonly developed corresponding to these surface morphologies a series of internal sedimentary structures including jigsaw structures inner shear zones aligned clasts diapiric structures convoluted laminations and basal decollements are also well developed through an analysis of these surficial and internal characteristics we propose that a rapid motion similar to a laminar flow most likely occurred after the avalanche mass detaching from the source area in this process the detached avalanche mass was mainly emplaced by a frictional simple shear process characterized by a bulldozing effect that occurred between the sliding mass and the substrate from the proximal to the distal sections of the avalanche the transport of the rock mass can be classified into four major processes an extension dominated sliding process in the transition zone a compression dominated sliding process in subzones iii 1 and iii 2 of the accumulation zone iii a sliding process co dominated by compression and lateral spreading in subzone iii 3 and a rapid radial spreading process in subzone iii 4 the results of our study provided an improved understanding of the transport mechanisms of this rock avalanche

earthquake induced chains of geologic hazards patterns mechanisms and impacts large earthquakes initiate chains of surface processes that last much longer than the brief moments of strong shaking most moderate and large magnitude earthquakes trigger landslides ranging from small failures in the soil cover to massive devastating rock avalanches some landslides dam rivers and impound lakes which can collapse days to centuries later and flood mountain valleys for hundreds of kilometers downstream landslide deposits on slopes can remobilize during heavy rainfall and evolve into debris flows cracks and fractures can form and widen on mountain crests and flanks promoting increased frequency of landslides that lasts for decades more gradual impacts involve the flushing of excess debris downstream by rivers which can generate bank erosion and floodplain accretion as well as channel avulsions that affect flooding frequency settlements ecosystems and infrastructure ultimately earthquake sequences and their geomorphic consequences alter mountain landscapes over both human and geologic time scales two recent events have attracted intense research into earthquake induced landslides and their consequences the magnitude m 7 6 chi chi taiwan earthquake of 1999 and the m 7 9 wenchuan china earthquake of 2008 using data and insights from these and several other earthquakes we analyze how such events initiate processes that change mountain landscapes highlight research gaps and suggest pathways toward a more complete understanding of the seismic effects on the earth s surface

transient water and sediment storage of the decaying landslide dams induced by the 2008 wenchuan earthquake china article earthquake triggered landslide dams are potentially dangerous disrupters of water and sediment flux in mountain rivers and capable of releasing catastrophic outburst flows to downstream areas we analyze an inventory of 828 landslide dams in the longmen shan mountains china triggered by the mw 7 9 2008 wenchuan earthquake this database is unique in that it is the largest of its kind attributable to a single regional scale triggering event 501 of the spatially clustered landslides fully blocked rivers while the remainder only partially obstructed or diverted channels in steep watersheds of the hanging wall of the yingxiu beichuan fault zone the size distributions of the earthquake triggered landslides landslide dams and associated lakes a can be modeled by an inverse gamma distribution b show that moderate size slope failures caused the majority of blockages and c allow a detailed assessment of seismically induced river blockage effects on regional water and sediment storage monte carlo simulations based on volumetric scaling relationships for soil and bedrock failures respectively indicate that 14 18 of the estimated total coseismic landslide volume of 6 4 14 6 10 9 m 3 was contained in landslide dams representing only 1 4 of the 60 000 slope failures attributed to the earthquake these dams have created storage capacity of 0 6 10 9 m 3 for incoming water and sediment about 25 of the dams containing 2 of the total river blocking debris volume failed one week after the earthquake these figures had risen to 60 20 and 90 90 within one month and one year respectively thus also emptying 92 of the total potential water and sediment storage behind these dams within one year following the earthquake currently only 0 08 10 9 m 3 remain available as natural reservoirs for storing water and sediment while 0 19 10 9 m 3 i e about a third of the total river blocking debris volume has been eroded by rivers dam volume and upstream catchment area control to first order the longevity of the barriers and bivariate domain plots are consistent with the observation that most earthquake triggered landslide dams were ephemeral we conclude that the river blocking portion of coseismic slope failures disproportionately modulates the post seismic sediment flux in the longmen shan on annual to decadal timescales

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

engineering risk mitigation measures for the landslide dams induced by the 2008 wenchuan earthquake abstract more than 257 sizable landslide dams were induced by the 2008 wenchuan earthquake which required timely risk mitigation measures this paper aims to summarize the engineering measures taken to mitigate the landslide dam risks provide a method for optimal design of spillways to minimize the risks and quantitatively evaluate practical options for spillway design with a physically based dam breach model the engineering measures taken to mitigate the risks of 37 highly hazardous landslide dams induced by the wenchuan earthquake are summarized an optimization method is proposed and applied to the spillway design for the tangjiashan landslide dam which is the largest one caused by the wenchuan earthquake it is found that the peak outflow rate could be reduced from the recorded 6500 m3 s to 2900 m3 s using the optimal design a spillway with a shallow and broad cross section is suitable for low erodibility dams while a spillway with a deep and narrow cross section is suitable for high erodibility dams a spillway with a large longitudinal gradient is beneficial for high erodibility dams with large dam widths and gentle downstream dam slopes a spillway close to one bank can reduce the peak outflow rate if the bank is erosion resistant

investigating error structure of shuttle radar topography mission elevation data product 1 an attempt was made to experimentally assess the instrumental component of error of the c band srtm srtm this was achieved by comparing elevation data of 302 runways from airports all over the world with the shuttle radar topography mission data product srtm it was found that the rms of the instrumental error is about 1 55 m modeling of the remaining srtm error sources including terrain relief and pixel size shows that downsampling from 30 m to 90 m 1 to 3 arc sec pixels worsened srtm vertical accuracy threefold it is suspected that the proximity of large metallic objects is a source of large srtm errors the achieved error estimates allow a pixel based accuracy assessment of the srtm elevation data product to be constructed vegetation induced errors were not considered in this work

predicting permeability from porosity using artificial neural networks permeability values in a borehole are predicted by an artificial neural network from the porosity values at the same depths the network used in this study employs an architecture called backpropagation that is good at making predictions the traditional approach for permeability prediction is regression analysis in regression analysis the relationship between porosity and permeability is assumed to be known in reality the functional form of this relationship i e the model equation is unknown in contrast the neural network approach assumes no functional relationship six wells from big escambia creek jurassic smackover carbonate field in southern alabama were used to test predicting permeability from porosity using a neural network porosity and spatial data alone were used to predict permeability because these data are readily available from any hydrocarbon field three scenarios were performed in each one a subset of the six wells was used for a training set one well for calibration and one or two wells were used for prediction for each scenario simple linear regression was also used to predict permeability from porosity the neural net predicted permeability much better than did regression in one scenario in the other two scenarios the two methods performed equally well the neural net predicted permeability accurately using minimal da a but other kinds of information e g log or core derived lithologic information are easily incorporated if available in addition compartmentalization of carbonate reservoirs may be recognizable by this approach

a large rockslide debris avalanche in cohesive soil at pink mountain northeastern british columbia canada abstract in early july 2002 a large rockslide debris avalanche occurred on the west slope of the pink mountain anticline in northeastern british columbia 57 04 n 122 52 w the slopes have been subjected to previous deformation and landsliding pre and post slide digital elevation models dems were created from aerial photography approximately 1 04 m m 3 of sandstone and shale travelled nearly 2 km from an elevation of 1460 m to 1010 m the landslide has a fahrboschung of 11 6 and covered 43 ha the rock debris entrained a certain amount of fine textured till and colluvium increasing its volume by 15 this entrainment caused partial liquefaction of the underlying soil thereby enhancing the mobility of the landslide we used a bingham rheological model to dynamically model the landslide with excellent correspondence between the analysis of the actual observed behaviour of the landslide

observations from the large rapid yigong rock slide debris avalanche southeast tibet the yigong rock slide debris avalanche yra which occurred on 9 april 2000 received worldwide attention as one of the largest nonseismic landslides in recent years with a volume of 0 3 109

performance of aster and srtm dems and their potential for assessing glacial lakes in the lunana region bhutan himalaya to assess the potential volume of a glacial lake outburst flood glof more precisely than in previous studies we analyze ground survey data and remote sensing digital elevation models dems around glacial lakes in the lunana region bhutan based on a dem generated from differential gps ground surveys we first evaluate the relative accuracies of dems produced by the advanced spaceborne thermal emission and reflection radiometer aster and the shuttle radar topography mission srtm root mean square errors of the altitudinal difference between these dems and ground survey data were 11 0 m for aster and 11 3 m for srtm these errors are similar to those of previous studies we show that a topographical classification allows a better estimate of elevation on lakes ponds riverbeds and glaciers due to their flat surfaces while the relative accuracy is worse over moraines and hill slopes due to their narrow ridges and steep slopes using the optical satellite images and the ground survey data we re evaluate the glof volume in 1994 as 17 2 5 3 10 6 m 3 we show glof related information such as distance altitudinal difference and gradient at possible outburst points where the lake level is higher than the neighboring riverbed and or glacial lake

esr dating of quartz extracted from quaternary and neogene sediments method potential and actual limits abstract esr dating of fluvial fluvio marine and beach sediment has been tested using the al centre in quartz grains from a basin and fossil beaches located around the manche channel dating was performed in conjunction with sedimentological stratigraphical and neotectonical studies the technical basis of the method is presented in the light of the study made on recent and fossil sediment in order to establish a procedure for the determination of the palaeodose the application on a neogene basin samples allows to push back the dating esr limits results show that esr dating of sediment can provide chronozons which are necessary to the uderstanding of the history of a basin where classical chronological markers do not exist

the maximum discharge of outburst floods caused by the breaching of man made and natural dams the sudden release of water impounded in natural and man made reservoirs has been responsible for some major disasters in mountainous regions of the world recent natural damming events and failures of natural dams have illustrated the need to examine the nature and magnitude of outburst floods and the behaviour of debris dams in general an empirical relationship between maximum discharge qmax and volume of water released during the outburst event vmax is established qmax 0 72vmax0 53 for man made dams and the relationship is thought applicable to the breaching of natural debris dams landslides and moraines this relationship allows a first order estimate to be made of qmax in the vicinity of the breach for a given vmax during the failure of a man made dam or a natural debris dam key words outburst floods man made dams natural dams landslide dam failure

morpho sedimentary and stratigraphic characteristics of the 2000 yigong river landslide dam outburst flood deposits eastern tibetan plateau abstract sedimentary characteristics of landslide dam outburst flood deposits are distinct from those of rainfall flood deposits due to their very high hydraulic energy and sediment concentration while they have been studied well in the geological record investigations of modern outburst flood deposits are relatively rare well preserved flood deposits and landforms caused by the june 2000 landslide dam outburst flood in the yigong river eastern tibet provide an opportunity to evaluate such sedimentological response to a high energy modern event the sedimentary characteristics of boulder bars and channel evolution over c 17 km downstream of the breach were investigated by field survey and remote sensing interpretation the results show that the post flood channel migrated downstream and increased in curvature the bar shape is relatively stable downstream but the bar area shows a fluctuating decrease poorly sorted accumulations composed of massive granular gravels and boulders near the breach indicate sediment rich bedload depositing processes occurred during rapid rising stage flows in contrast there are eddy bars and deposition of fine gravel with horizontally bedded laminations 17 km downstream of the landslide suggesting suspended sediment dominated deposition with a rapid loss of transport capacity comparison with previous hydrodynamic simulations indicates that the rates of the rising stage and the falling stage strongly affect the sedimentary characteristics of boulder bars and slackwater deposits

layered internal structure and breaching risk assessment of the higashi takezawa landslide dam in niigata japan the internal structure and geotechnical properties of landslide dams have rarely been examined in detail although they largely control the longevity and potential failure mechanisms of the dams during the 2004 mid niigata prefecture earthquake thousands of landslides were triggered and many landslide dams were formed in the imo river basin among these landslides dams the biggest one that occurred in the higashi takezawa district threatened both the upstream and downstream areas emergency and eventual permanent countermeasures were successfully performed to mitigate the hazards presented by the dam the preserved landslide dam provides a good field study area for improving understanding of the formation and stability of similar features to characterize its internal structure and to provide more reliable information for stability analysis we used a multiple channel surface wave technique and microtremor array measurements to survey the dam s s wave velocity v s profile our results show that the integrated use of these methods is an effective approach for determining the s wave velocity structure of landslide dams irrespective of the mountainous environment in which they typically occur the v s profile suggests that the displaced landslide materials had been little disturbed during movement although movement was rapid and over a long distance we also discuss herein the landsliding mechanism and assess the breaching risk of the landslide dam due to overtopping c 2016 elsevier b v all rights reserved

the 1786 earthquake triggered landslide dam and subsequent dam break flood on the dadu river southwestern china abstract chinese historic documents recorded that on june 1 1786 a strong m 7 75 earthquake occurred in the kangding luding area sichuan southwestern china resulting in a large landslide that fell into the dadu river as a result a landslide dam blocked the river ten days later the sudden breaching of the dam resulted in catastrophic downstream flooding historic records document over 100 000 deaths by the flood this may be the most disastrous event ever caused by landslide dam failures in the world although a lot of work has been carried out to determine the location magnitude and intensity of the 1786 earthquake relatively little is known about the occurrence and nature of the landslide dam in this paper the dam was reconstructed using historic documents and geomorphic evidence it was found that the landslide dam was about 70 m high and it created a lake with a water volume of about 50 106 m3 and an area of about 1 7 km2 the landslide dam breached suddenly due to a major aftershock on june 10 1786 the peak discharge at the dam breach was estimated using regression equations and a physically based predictive equation the possibility of a future failure of the landslide seems high particularly due to inherent seismic risk and detailed geotechnical investigations are strongly recommended for evaluating the current stability of the landslide

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

astronomic timescale for the pliocene atlantic δ18o and dust flux records of ocean drilling program site 659 high resolution benthic oxygen isotope and dust flux records from ocean drilling program site 659 have been analyzed to extend the astronomically calibrated isotope timescale for the atlantic from 2 85 ma back to 5 ma spectral analysis of the 18o record indicates that the 41 kyr period of earth s orbital obliquity dominates the pliocene record this is shown to be true regardless of fundamental changes in the earth s climate during the pliocene however the cycles of sahelian aridity fluctuations indicate a shift in spectral character near 3 ma from the early pliocene to 3 ma the periodicities were dominantly precessional 19 and 23 kyr and remained strong until 1 5 ma subsequent to 3 ma the variance at the obliquity period 41 kyr increased the timescale tuned to precession suggests that the pliocene was longer than previously estimated by more than 0 5 m y

study on the progressive fracturing in soil and rock mixture under uniaxial compression conditions by ct scanning abstract soil and rock mixture srm is very common in engineering as a type of extremely heterogeneous and anisotropic geological material srm is easy to fracture and damage under external forces which often causes geological disasters such as landslide and debris flow therefore study on the progressive fracturing of this material is very important for geological engineering in this paper uniaxial compression test with real time computed tomography ct scanning was conducted on srm samples with rock percentage of 40 the evolutions of visible fractures invisible fractures in ct slices average density and heterogeneity of the sample during loading process were all studied quantitatively this research finds that invisible fractures occur soon once loading begins gradually accumulate in elastic deformation stage and finally form visible fractures in plastic deformation stage average density of the whole sample slightly declines while heterogeneity greatly increases during the evolution of fracturing

distribution of landslides adjacent to the northern side of the yarlu tsangpo grand canyon in tibet china this paper presents results of recent studies on distribution and category of landslides in one section of the sichuan tibet highway adjacent to the northern side of the yarlu tsangpo grand canyon tibet southwestern china in the tectonic setting predominated by compression and strike slipping active faults are dominant and result in the genesis of the great alpine relief together with fluvial incision and unloading in this section with a distance of about 290 km between ranwu and lulang 34 landslides occurred among them the 12 large and super large landslides comprise the most dangerous part of the highway system to road users over the past 50 years the landslides usually occurred in slopes comprised of moraine with a large thickness fluvio pluvial and lacustrine deposits and fractured rocks based on the examination of the physical geography structural geology quaternary geology stratigraphy and petrography this paper presents the temporal spatial distribution of landslides along the section and classification of them into three types with respect to mechanism and composites of landslides type 1 landslide initiated at high elevation and transformed into a distal debris flow damming the river with a long reoccurrence interval type 2 landslide at stream banks in different ranks of mass movements in dissecting layers of moraines type 3 landslide of fractured rock mass with quick translation movements each of the three types is presented by distinctive case examples type 1 is yigong landslide type 2 includes dongjiu landslide group 102 landslide group suotong landslide group songzong landslide and the type 3 is layue landslide a binary landslide which is seldom seen in nature and which occurred in the outlet of one creek under the integrative function of fluvial incision and road cut is also presented these are distributed in different parts of the area with characterized structural geology topography and composites gneiss and quaternary deposits with accumulative quantity between suotong and dongjiu the most occurred with frequent and rapid translation shallow shearing planes various influential factors and unique triggering factors and a variable period of reoccurrence with a tendency of increasing magnitude in this region six influential factors greatly contribute to their occurrence a intensive neotectonic movements b ongoing alpine canyon relief c earthquakes d heavy precipitation e stream erosion and f human activities to a certain extent mostly the latter four factors play major roles in triggering landslide occurrence the earthquake causes the rock and soil to fracture and deform and tends to be unstable or cause earth induced landslides the heavy rainfall in monsoon seasons which saturates the soil and lower the shearing strength is mostly responsible for the occurrence of landslides the stream erosion disturbs slope toes causing progressive failure road construction and deforestation decrease the natural slope stability comments and suggestions on the physical measures for remediation of landslides and safety of highways are also made

erosion of the tsangpo gorge by megafloods eastern himalaya at the southeastern margin of the tibetan plateau the yarlung tsangpo river plunges through the himalaya to drop 2 km through the tsangpo gorge upstream relict glacial dams and impounded lake terraces suggest that quaternary lakes as large as 800 km 3 catastrophically drained through the gorge as megafloods we report on new megaflood deposits downstream of the gorge and use detrital zircon u pb provenance data to demonstrate that these high magnitude events originated in tibet and more effectively focused erosion in the gorge than both the extremely erosive modern peak flows and one of the largest landslide dam outburst floods ever documented our findings support the proposition that in this steep narrow gorge where hillslope angles are near the threshold angle of bedrock failure megafloods provide a mechanism to rapidly evacuate hillslope material and focus erosion on channel adjacent hillslopes although megaflood frequency remains unconstrained we demonstrate the capability of these events to contribute substantially to rapid exhumation in this region

empirical prediction of coseismic landslide dam formation in this study we develop an empirical method to estimate the volume threshold for predicting coseismic landslide dam formation using landscape parameters obtained from digital elevation models dems we hypothesize that the potential runout and volume of landslides together with river features determine the likelihood of the formation of a landslide dam to develop this method a database was created by randomly selecting 140 damming and 200 non damming landslides from 501 landslide dams and 60 000 landslides induced by the mw 7 9 2008 wenchuan earthquake in china we used this database to parameterize empirical runout models by stepwise multivariate regression we find that factors controlling landslide runout are landslide initiation volume landslide type internal relief h and the h l ratio between h and landslide horizontal distance to river l in order to obtain a first volume threshold for a landslide to reach a river the runout regression equations were converted into inverse volume equations by taking the runout to be the distance to river a second volume threshold above which a landslide is predicted to block a river was determined by the correlation between river width and landslide volume of the known damming landslides the larger of these two thresholds was taken as the final damming threshold this method was applied to several landslide types over a fine geographic grid of assumed initiation points in a selected catchment the overall prediction accuracy was 97 4 and 86 0 for non damming and damming landslides respectively the model was further tested by predicting the damming landslides over the whole region with promising results we conclude that our method is robust and reliable for the wenchuan event in combination with pre event landslide susceptibility and frequency size assessments it can be used to predict likely damming locations of future coseismic landslides thereby helping to plan emergency response copyright 2014 john wiley sons ltd

geohazard cascade and mechanism of large debris flows in tianmo gully se tibetan plateau and implications to hazard monitoring abstract alpine glaciers and permafrost are sensitive to climate change and their degradation due to annual temperature increasing has already induced many mass movements such as debris flows on september 4 of 2007 july 25 31 and september 5 8 of 2010 three large debris flows took place in tianmo gully a left bank tributary of parlung river southeast tibetan plateau the debris flows blocked the river and a section of highway 450 m long including a bridge 76 m long were destroyed by the subsequent outburst flood this paper based on post event investigations witness accounts news reports and satellite image interpretation systematically analyses the geo environments climate conditions and sources of these debris flow events their differences in flow process surge numbers and velocity suggest that they resulted from different geohazard processes cascades and initiation mechanisms the 2007 debris flow originated from a bare rock moraine collapse next to the cirque due to strong alternation of wet and dry conditions the mass moved down the gully with velocity of 30 40 m s estimated by back calculation using superelevation and run up it entrained moraine avalanched snow ice and water from the channel and transformed into high speed debris flow crossing the parlung river and finally depositing onto the highway the other two events in july and september of 2010 initiated from two channel bank landslides triggered by melt water and concentrated rainfall which dammed the channel the subsequent landslide dam failure generated debris flows over several days with velocities of 12 14 m s that temporally blocked parlung river the initiation mechanisms of most large debris flows recorded in parlung region are similar to the events in tianmo gully originating either from rock moraine avalanches or from the collapse of a landslide dam this implies that the periglacial degradation of bedrock and moraine is the key process to be monitored and assessed under climate warming the paper applies the geohazard mechanisms and cascade to hazard monitoring in order to protect the existing sichuan tibet highway and the forthcoming railway

evaluation of aster gdem and srtm and their suitability in hydraulic modelling of a glacial lake outburst flood in southeast tibet the resolution and accuracy of digital elevation models dems can affect the hydraulic simulation results for predicting the effects of glacial lake outburst floods glofs however for the tibetan plateau high quality dem data are often not available leaving researchers with near global freely available dems such as the advanced spaceborne thermal emission and reflection radiometer global digital elevation model aster gdem and the shuttle radar topography mission data srtm for hydraulic modelling this study explores the suitability of these two freely available dems for hydraulic modelling of glofs our study focused on the flood plain of a potentially dangerous glacial lake in southeastern tibet to evaluate the elevation accuracy of aster gdem and srtm and their suitability for hydraulic modelling of glofs the elevation accuracies of aster gdem and srtm were first validated against field global position system gps survey points and then evaluated with reference to the relatively high precision of 1 50 000 scale dem dem5 constructed from aerial photography moreover the dem5 aster gdem and srtm were used as basic topographic data to simulate peak discharge propagation as well as flood inundation extent and depth in the hydrologic engineering center s river analysis system one dimensional hydraulic model results of the three dem predictions were compared to evaluate the suitability of aster gdem and srtm for glof hydraulic modelling comparisons of aster gdem and srtm each with dem5 in the flood plain area show root mean square errors between the former two as 15 4 m and between the latter two as 13 5 m although srtm overestimates and aster gdem underestimates valley floor elevations both dems can be used to extract the elevations of required geometric data i e stream centre lines bank lines and cross sections for flood modelling however small errors still exist in the cross sections that may influence the propagation of peak discharge the flood inundation extent and mean water depths derived from aster gdem predictions are only 2 2 larger and 2 3 m deeper than that of the dem5 predictions whereas the srtm yields a flood zone extent 6 8 larger than the dem5 prediction and a mean water depth 2 4 m shallower than the dem5 prediction the modelling shows that in the absence of high precision dem data aster gdem or srtm dem can be relied on for simulating extreme glofs in southeast tibet copyright 2011 john wiley sons ltd

controls on reservoir development in a shelf carbonate upper jurassic smackover formation of alabama hydrocarbon reservoirs of the upper jurassic smackover formation in alabama are predominately oolitic and pelletal dolostone pore systems are dominated by moldic and secondary intraparticle pores intercrystalline pores or mixtures of these pore types all smackover reservoirs in alabama have been strongly affected by early cementation dissolution of calcium carbonate allochems and dolomitization marine phreatic cement occluded primary interparticle porosity in much of the smackover reservoirs in alabama dolomitization of the smackover in alabama included penecontemporaneous early burial and late deep burial episodes early burial dolomite predominates fabric selective dolomitization yielded reservoirs strongly influenced by both depositional fabric and diagene is nonselective dolomitization yielded reservoirs with intercrystalline pore systems shaped primarily by diagenesis porosity evolution was controlled regionally by level of thermal exposure mode of dolomitization and proximity to the wiggins arch thermal exposure is inversely related to porosity but the relationship is weak r2 0 5 fabric selective dolostone is slightly more porous than nonselective dolostone when averaged over the entire study area averages of 18 1 and 15 1 respectively p 0 0001 but nonselective dolostone is more porous at a given level of equivalent vitrinite reflectance smackover fields on the north flank of the wiggins arch are unusually porous given their level of thermal maturity and are unusual in other ways as well local porosity variation was controlled by depositional fabric early cementation dissolution and burial compaction and cemen ation regional permeability variation cannot be explained using existing data permeability is locally controlled by pore throat size the effects of dolomite crystal size distribution early cementation fracturing and burial compaction and cementation pore throat size exhibits the strongest overall correlation with permeability r2 0 54 permeability and porosity are strongly correlated locally but the regional correlation is weak

modelling the space time evolution of bed entrainment for flow like landslides abstract the paper discusses the space time evolution of bed entrainment for some typical flow like landslides in three different test areas first the attention is focused on debris avalanches da whose lateral spreading is highly affected by bed entrainment two cases of debris avalanches turning into debris flows df i e channelized flows are then investigated to discuss the potential occurrence of complex bed entrainment scenarios a quasi 3d depth integrated coupled sph smooth particle hydrodynamic model is used the numerical results show that i the eroded thicknesses have maximum values in the intermediate portion of the debris avalanche path and ii the computed time variations of eroded thicknesses and the entrainment rates are consistent with those indicated in recent literature for das at the studied areas in addition the computed scenarios are differentiated in terms of unitary flow discharge identifying the typical behaviour of small volume da landslides propagating inside gullies as dfs and combined dfs and das

prediction of the overtopping induced breach process of the landslide dam abstract timely prediction of a landslide dam breach is particularly important for assessments of expected disaster consequences and to plan emergency responses however due to the complex composition and specific geotechnical properties of the landslide dam material such a prediction is challenging in this study geological survey results and landslide dam breach mechanisms were used to develop a numerical model for overtopping induced landslide dam breaches considering variation of soil erodibility with depth the model included a hydrodynamic process module a soil erosion module and a breach evolution module moreover a time step iteration algorithm was adopted to simulate the soil and water coupling process during dam breach a comparison of calculated and measured breach hydrographs variations of dammed lake water level breach sizes as well as two other typical models were used to validate the rationality of the numerical model by considering the baige landslide breach case of november 3 2018 with detailed measured data parameter sensitivity analysis showed that the soil erodibility coefficient exerted an important influence on the breach process while soil critical shear stress had a relatively small influence which remained within 15 for output parameters when it was multiplied by 0 5 1 0 and 2 0 furthermore spillway excavation was found to significantly reduce the peak breach flow if the dammed lake has a large storage capacity thus identifying it as an effective measure for disaster mitigation

optical dating of holocene sediments from a variety of geomorphic settings using single grains of quartz this paper presents an improved method for the optical dating of holocene sediments from a variety of geomorphic settings we have measured the equivalent dose de in individual grains of quartz using green laser light for optical stimulation and have simulated the de distributions for multiple grain synthetic aliquots using the single grain data for 12 samples of known independent age we show that application of a minimum age model to the single grain and small 10 grain aliquot de data provides the most accurate estimate of the burial dose for nine of the samples examined 3 aeolian 5 fluvial and 1 marine the weighted mean de as obtained using the central age model gives rise to burial age overestimates of up to a factor of 10 for these nine samples whether single grains small aliquots or large 100 grain aliquots are used for the other three samples two aeolian and one fluvial application of either the minimum age model or the central age model to the single grain small aliquot and large aliquot de data yields burial ages in accord with the independent age control we infer that these three samples were well bleached at the time of deposition these results show that heterogeneous bleaching of the optical dating signal is commonplace in nature and that aeolian transport offers no guarantee that the sample will be well bleached at the time of deposition we also show that grains sensitive to infrared ir stimulation can give rise to low de values which will result in significant underestimation of the burial dose and hence of the age of deposition we demonstrate that use of a modified single aliquot regenerative dose protocol incorporating ir stimulation prior to green light stimulation deals effectively with contamination by ir sensitive grains we conclude that application of the modified protocol to single grains or small aliquots of quartz using the lowest de population to estimate the burial dose is the best means of obtaining reliable ages for holocene sediments from a wide range of depositional environments d 2003 elsevier b v all rights reserved

modeling lateral enlargement in dam breaches using slope stability analysis based on circular slip mode abstract evaluation of breach flood of landslide or artificial dams is usually performed by combining the hydraulic modeling of the breach flow and geotechnical analysis of the breach channel stability this paper is a continuation of the previous work which mainly focused on the hydraulic aspects of a dam breach flood efforts have been made to improve the related slope stability analysis approach that traditionally adopts a simple wedge failure mode the improvements includes a vertical cut at the slope toe due to soil erosion an approach to determine the critical slip surface the effective and total stress methods dealing with different dam materials and a procedure to model the stepped failures of the breach bank due to continuous toe cutting using vba programming an excel spreadsheet entitled dbs iwhr has been developed to perform the stability analysis this spreadsheet has been incorporated into another spreadsheet entitled db iwhr for the calculation of the flood hydrograph the developed model has been tested by back analysis of the yigong landslide dam breached at the tibetan plateau in china in 2000 with a flood peak of 94 013 m 3 s the calculated results of the final breach base level and the peak discharge are in good agreement with the field data further the results are shown to be insensitive to the variations in the geotechnical parameters used in the model

a super large landslide in tibet in 2000 background occurrence disaster and origin on april 9 2000 a super large landslide 3 x 10 8 m 3 occurred along zhamu creek southeast tibet as a result a landslide dam formed and the yigong river was blocked a channelized diversion was constructed for prevention of overtopping two months later on june 10 a catastrophic flood resulting from the failure of the landslide dam caused a serious loss of property this is the second of landslide occasion dam formation and flooding occurrence at the same site since 1900

entrainment of debris in rock avalanches an analysis of a long run out mechanism many rock avalanches entrain and liquefy saturated soil from their paths evidence for this includes mud displaced from the margins of rock avalanche deposits substrate material smeared along the base of deposits extrusion of liquefied soil upward through the deposits and increases of volume a hypothesis first suggested in 1881 and since reinforced by several authors suggests that entrainment of substrate material increases mobility although the process has been discussed in the literature for more than 100 years few detailed and quantitative descriptions exist the main purpose of this paper is to describe two recent cases from british columbia canada where rockslides entrained substrate on a very large scale influencing the character of the events estimated volume balance curves based on detailed field mapping are provided for both cases dynamic analyses are carried out using a numerical model and using the same set of rheological parameters the mechanism of material entrainment and displacement is discussed the data suggest that rapid rock failures entraining very large quantities of saturated substrate material represent a special type of landslide transitional between rock avalanche and debris avalanche many rock avalanches can thus be seen as end members of a continuum of phenomena involving rock failure followed by interaction with saturated substrate

the formation and impact of landslide dams state of the art abstract the blocking of river courses by mass movements is very common in mountainous areas with deep and narrow valleys landslide dams may pose serious threats to people and their livelihoods downstream in the case of abrupt dam failure since the publication of benchmark reviews of costa and schuster 1988 and korup 2002 there is a growing number of studies focusing on the formation stability and short term impacts of landslide dams this review combines the insights of all these studies builds on current concepts of landslide dams and suggests ways to unify terminologies and classifications we furthermore present a new worldwide database compiled from literature data it contains 410 landslide dams 1 million m3 in volume that were formed since 1900 since these have the most complete data entries these data show that dam longevity is among other factors correlated with the type of landslide forming the dam those formed by rock debris avalanches and rockslides have longest lifespans however the influence of landslide type or material on dam longevity decreases with time after dam formation to ensure consistency in the next database generation we suggest guidelines for data collection to provide a solid basis for evaluating dam stability and governing factors a preliminary classification matrix for landslide dam stability that combines topographic setting and the internal structure of the dam body is another outcome of our review furthermore an evaluation of the various geomorphic stability indices proposed in the literature regarding their suitability and limitations in assessing dam formation and stability shows that they predict the probability of dam formation reasonably well but that their application to longevity estimates requires further assessment the geomorphic impacts of landslide dams in the short medium and long term are summarized and illustrated with key examples finally for a better understanding of the factors controlling dam stability we recommend to 1 include dam composition and sedimentary structures in future case studies 2 maintain and update the worldwide database for sound statistical analyses 3 refine landslide dam stability indices and test them for different landslide types and 4 study hazard cascades related to multiple dams in one watershed for long term landscape evolution studies we suggest to 5 quantify terrestrial sediment flux related to landslide dams 6 detect ancient landslide dams in river profiles and 7 further exploit the sediment archives in former impoundment areas

rock slope failure and the river long profile this study examines the geomorphic effects of large 10 6 m 3 rock slope failures on long profiles of rivers in the swiss alps and the new zealand southern alps regression of channel slope versus drainage basin area objectively highlights knickpoints separating incised from aggraded reaches that often correspond to locations of large rock slope failures for a fixed concavity index the highest values of the steepness index and erosion index along a given profile spatially coincide with breach channels cut into formerly river damming rockslide debris as old as 10 k y assuming that the knickpoints do not predate slope failure data show that high profile steepness and inferred specific stream power are not always the cause but often a result of large river blocking rock slope failure in mountain basins omission of rockslide data from slope area plots lowers the steepness index and increases the concavity index on average yet only in few cases more than one standard deviation

the 1939 montagneuse river landslide alberta the 1939 landslide on the west wall of the montagneuse river valley 1300 m long 1400 m wide and 80 m thick with av olume of 76 10 6 m 3 is the largest historic rapid landslide on the interior plains of canada it lasted about a minute dammed the river and formed a reservoir 1 5 km long the reservoir was filled before 1952 by lake deposits which were eroded by the river by 1988 the landslide contained two major blocks the downslope block 950 m long kept intact without obvious tilting indicating that the block moved almost horizontally on a comparatively deep rupture surface the displaced material included part of the preslide river channel so the montagneuse river was pushed eastward the toe of the block moved up and dammed the river the upslope block with a length of 300 350 m slid with little rotation but broke up into at least five smaller blocks most trees on the upslope block postdate the slide two sag ponds on the landslide visible in 1952 had enlarged by 1988 probably a result of water running off from the recently cleared farmland behind the scarp the main scarp has been substantially modified by earth flows and slides landslides in the montagneuse river valley coincide with the shaftesbury buried preglacial channel of the peace river the surfaces of rupture of five historic landslides in the peace river lowland follow clays deposited in preglacial channels confirming that these deposits may be hazardous when eroded

petrologic and structural controls on geomorphology of prehistoric tsergo ri slope failure langtang himal nepal high relief h up to 2600 m and spatial orientation of discontinuities such as leucogranitic intrusions mylonitic and pseudotachylitic horizons and related ore structures were the preparatory causal factors for the giant prehistoric tsergo ri landslide high himalayan crystalline langtang himal nepal other controlling factors include overthrusting detachment faulting and paleoseismics related to the main central thrust mct and southern tibet detachment system stds neotectonically generated structures and predesigned form of the scarp broken crest and the direction of movement towards the wsw coherently displacement of several 109 m3 materials caused frictional fusion landslide dynamics and specific morphologic conditions created four different types of sliding surfaces in chronological sequence i primary at the basement ii secondary parallel or subparallel to i iii tertiary vertical to i and ii and iv quarternary sliding surfaces local variety of iii note ordinal numeric terms are not in time stratigraphic sense these planes represented the main discontinuities conducting different syn event stresses in the sliding mass and for further landslide dynamics spatial difference and widespread distribution of sliding planes and sets of discontinuities all over the landslide area caused different classes of rock quality which subsequently determined specific erosional processes within the landslide accumulation area the subsequent glacial and fluvial erosional processes were controlled by the correlating preexisting lithotectonic patterns the hyalomylonitic and or breccious sliding planes and the recent morphologic features or shapes of tsergo ri i the se part is gradationally brecciated to the top and includes tsergo ri itself the residual mass of the bulk has been eroded almost isometrically as far as the primary sliding plane crops out along the intact gneissic basement differences in rock quality along a horizon of secondary sliding planes indicate a steplike break in the relief after the last main glaciation ii the earlier halted nw part still preserved micromountainous shape of compact sliding blocks phushung i and ii kyimoshung separated by landslide dynamic triggered faults tertiary and quarternary sliding planes primary and secondary sliding planes almost covered by holocene sediments produced an insignificant morphology iii the highest brecciated strike slip fault generated during collision with the obstacle of pangshungtramo peak in the southwest is the deeply eroded dranglung chu valley which has been kept morphologically active in a major way until recent times iv except for the collision obstacle of pangshungtramo peak with recent semi active erosion and a small secondary rockslide block of tsangbu north of it all surrounding parts show typical features of high altitude erosion

quaternary moraines vs catastrophic rock avalanches in the karakoram himalaya northern pakistan a history and conception of glacial events for the central karakoram himalaya proposed some 80 years ago by giotto dainelli are largely accepted today however certain deposits identified as terminal moraine complexes marking glacial episodes were actually emplaced by rock avalanches in the skardu and shigar intermontane basins of baltistan at least 15 rock avalanche events were previously mapped as moraine or till criteria used for distinguishing these catastrophic landslide deposits emphasize homogeneous lithology of rubble and matrix clast shape facies characteristics the large scale unity of emplacement and morphological relations to valley topography the deposits of three events at katzarah satpura and the north end of shigar valley have been reconstructed in detail thick supraglacial debris does not result in similar deposits extensive valley fills river terraces large sediment fans and lacustrine sediments formerly attributed to late glacial conditions are reinterpreted as postglacial events involving rock avalanches that interrupted fluvial development existing reconstructions of glaciations are left in doubt especially late glacial events in the central karakoram as are the roles assigned to karakoram main indus valley and western himalayan ice

simple scaling of catastrophic landslide dynamics catastrophic landslides involve the acceleration and deceleration of millions of tons of rock and debris in response to the forces of gravity and dissipation their unpredictability and frequent location in remote areas have made observations of their dynamics rare through real time detection and inverse modeling of teleseismic data we show that landslide dynamics are primarily determined by the length scale of the source mass when combined with geometric constraints from satellite imagery the seismically determined landslide force histories yield estimates of landslide duration momenta potential energy loss mass and runout trajectory measurements of these dynamical properties for 29 teleseismogenic landslides are consistent with a simple acceleration model in which height drop and rupture depth scale with the length of the failing slope

analysis of gradual earth dam failure analytical models are developed for the simulation of earthdam breach erosion using a reservoir water mass depletion equation broad crested weir hydraulics and a breach erosion relation solutions are derived for rectangular triangular and trapezoidal shaped breaches breach erosion is assumed to be either a linear or quadratic function of the outflow mean water velocity historical data are used to test the models a sensitivity analysis is performed to determine the importance of the various parameters involved

characterization of reservoir lithologies within subunconformity pools pekisko formation medicine river field alberta canada the pekisko formation in western canada is a third order sequence comprised of an open marine grainstone through restricted carbonate mudstone succession truncation of the pekisko along an unconformity edge prior to the jurassic and several periods of incision from early jurassic early cretaceous have formed an intricately sculptured subcrop belt in the medicine river field oil is trapped in discrete pools close to the unconformity edge reservoir facies comprise three lithologies medium crystalline dolostone with intercrystalline and vuggy porosity forms the reservoir in an elongate dolostone body that has replaced grainstone fine crystalline dolostone is facies selective within a lime mudstone unit in which the common reservoir rock is bioturbated dolomudstone with intercrystalline porosity grainstones have secondary porosity formed though leaching of microcrystalline calcite allochems and intergranular cements reservoir quality is assessed from consideration of orthogonal permeability values kmax maximum horizontal permeability k90 horizontal permeability at 90 to the maximum and kv vertical permeability obtained from conventional whole core analyses sedimentary lamination primarily affects the kv and the presence of fine grained lamination dictates that kv 3k90 and kv k90 from this relationship the fracture density in all three lithologies appears to be similar low and variable porosity and permeability values in grainstones indicate that the fracture system is poorly connected to the matrix despite leaching and fracturing at the unconformity edge reservoir distribution closely follows patterns of facies that were susceptible to dolomitization future exploration potential lies in fine crystalline dolostone bodies that may form stratigraphic traps downdip from the unconformity edge

electron spin resonance optical dating of marine estuarine and aeolian sediments in florida usa abstract for the first time electron spin resonance optical dating esrod has been conducted on littorally transported and aeolian siliciclastic sediments in florida esrod utilizes light sensitive radiation sensitive defects at silicon sites that have been replaced by aluminum and titanium atoms to give rise to a time dependant signal these defects saturate at higher levels of radiation dose compared to optically stimulated luminescence and therefore extend the optical dating range back into the millions of years our results show that the trail ridge sequence is a multi depositional unit that began deposition around 2 2 ma and continued until 6 ka the osceola cape of the effingham sequence was deposited around 1 5 ma and the chatham sequence was a multi depositional terrace with at least three events preserved

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

provenance and erosional impact of quaternary megafloods through the yarlung tsangpo gorge from zircon u pb geochronology of flood deposits eastern himalaya abstract holocene and upper pleistocene sediments in the eastern himalayan syntaxis represent an extraordinary record of glacial outburst megafloods in one of the most tectonically active landscapes on earth glacial damming and outburst floods in the syntaxis may have focused erosion in the steep tsangpo gorge and inhibited river incision into the margin of the tibetan plateau however few flood slackwater deposits have been studied and it is unknown which of the hundreds of known glacial impoundments in tibet may have sourced the floods here we report n 1438 new detrital zircon u pb data from individual ancient megaflood and historical outburst flood slackwater deposits to examine the provenance and erosive potential of these events detrital zircon u pb geochronology of megaflood deposits show that megaflood provenance is more consistent with impoundment of the yarlung river drainage at or west of the namche barwa massif than impoundment of eastern drainages along the yigong and parlung rivers compared to active bedload in the siang river and historical floods within the same drainage area megaflood samples overall contain a disproportionately large amount of zircons eroded from the tsangpo gorge we interpret this preferential derivation to reflect preferential erosion during large discharge events supporting the hypothesis that quaternary megafloods are a primary contributor to rapid exhumation of the eastern himalayan syntaxis

paleoceanographic model of neogene phosphorite deposition u s atlantic continental margin the neogene stratigraphic section of the southeastern u s continental shelf coastal plain system is characterized by i a series of major regional phosphogenic episodes ii a strong spatial relationship between the structural or topographic framework and phosphate deposition and iii distinct cyclical and regional patterns of deposition of the terrigenous carbonate and phosphate lithofacies the complex depositional patterns are explained by a paleoceanographic model based upon the interaction of glacial eustatic sea level fluctuations associated changes in climate and the dynamics of the gulf stream in response to the bathymetric configurations of the continental margin during the past 20 million years

correlations of fluvial knickzones with landslide dams lithologic contacts and faults in the southwestern annapurna range central nepalese himalaya 1 we investigate the role of landslide dams spatial changes in lithology and rock uplift on faults in the formation of knickzones on bedrock rivers we focus our analysis in the southwestern annapurna range of the central nepalese himalaya where detailed geologic maps topographic data field observations and aerial photographs are available we identified knickzones in our study area from normalized river steepness indices ksn values extracted from river longitudinal profiles derived from a 25 m digital elevation model we interpolated from digitized topographic map contours we compared the location of these knickzones with 1 lithologic contacts and faults from a detailed geologic map of the modi khola valley and 2 inferred ancient landslide dam features mapped from field observations and aerial photographs the steepest location on the modi khola occurs near the same latitude as the steepest reach on the mardi khola located directly to the east potentially highlighting a major topographic transition across the annapurna however we find that landslide dams once blocked the flow of the modi khola and damming followed by incision after landslide breaching can explain the location of these knickzones without the need for active faulting near the main central thrust we also conclude that 1 knickzones do not correlate with any spatial changes in lithology and 2 knickzones generated by rock uplift on unmapped faults cannot be ruled out we emphasize that disentangling the processes responsible for knickzone formation remains challenging even when high resolution geologic and topographic data are available

modelling rock avalanche propagation onto glaciers abstract ice rock avalanches which occur in glacial environments are controlled by the presence of snow and ice in the moving material and by possible propagation onto icy basal surfaces all these factors contribute to enhancing the flow mobility mixing with ice and snow hampers block collisions and favours dense flow behaviour ice melting reduces granular friction by saturation of the basal material and fluidization effects propagating onto glaciers offers a smooth surface with low shear resistance this work is a review of the best documented ice rock avalanches and focuses on evaluating their mobility for hazard analysis purposes by providing a set of calibrated cases the rock avalanches have volumes ranging from 5 10 6 m 3 to 25 10 6 m 3 we replicate these events by using sph and fem numerical methods assuming frictional and voellmy basal rheologies the voellmy rheology best performs at replicating the landslide propagation among the back analyzed cases the frictional coefficient ranges in the interval 0 03 0 1 the turbulent coefficient within 1000 m s 2 2000 m s 2 the bulk basal friction angle ranges within 2 75 and 14 with values inversely related to event volumes forward selection of the basal friction angle based on event volume allows the replication of the mount cook ice rock avalanche predicting a maximum runout which is less than 4 larger than observed in the perspective of forward modelling large uncertainty is related to the reconstruction of the post event topographies particularly for the sliding surface mixing with ice and snow reduces basal friction proportionally to ice and snow content pure ice has a basal friction which is reduced by about 75 than basal friction of pure rock melting of ice during rock avalanche propagation has been evaluated for the sherman event the frictional heat generated at the glacier surface results in the melting of 86 2 5 9 kg m 2 which could have contributed to a minimum 20 35 10 reduction of the material friction angle through the sole pore pressure generation within a 40 and 20 cm thick shear layer respectively the largest uncertainty is related to the area of contact between rock and ice

landslides triggered by the 1949 khait earthquake tajikistan and associated loss of life abstract earthquake triggered landslides are a major geological hazard in central asia in july 1949 the m7 4 khait earthquake triggered many hundreds of landslides in a mountainous region near the southern limit of the tien shan mountains central tajikistan these landslides involved widespread rock slope failure as well as large numbers of flowslides in loess that mantles the steep slopes of the region in the yasman valley hundreds of loess landslides coalesced to form a massive loess flow est vol 245 mm 3 that travelled up to 20 km on a slope of only 2 in an adjacent valley the khait landslide involved transformation of an earthquake triggered rockslide into a very rapid flow by the entrainment of saturated loess into its movement it travelled 7 41 km over a vertical distance of 1421 m with an estimated average velocity of 30 m s we estimate its volume as 75 mm 3 an order of magnitude less that previously published estimates the khait landslide was simulated using dan the number of casualties due to earthquake triggered landslides in the epicentral region was considerable approximately 4000 people were killed in the yasman valley loess flow as 20 villages kishlaks were overwhelmed in the khait landslide alone we estimate ca 800 people lost their lives when the villages of khait and khisorak were overrun by rapidly moving debris our data indicates that a total of approximately 7200 people were killed by earthquake triggered landslides in the epicentral region of the khait earthquake and that in terms of loss of life the 1949 yasman valley loess flow was one of the most destructive landslides in recent history

the evolution of the samaoding paleolandslide river blocking event at the upstream reaches of the jinsha river tibetan plateau abstract a large number of landslides have occurred in the upstream reaches of the jinsha river tibetan plateau due to the intensity of tectonic movement in the area remote sensing and field investigation indicate that one of them the samaoding paleolandslide previously blocked the river various river blocking phenomena are well preserved including the old landslide dam and deposits fluvial sediments and hydrostatic sandy sediment to better understand the evolution of the samaoding landslide the authors carried out thermoluminescence tl dating and numerical simulations the tl analysis shows that the landslide occurred at 10 6 0 5 ka bp discrete element method dem simulation of the landslide based on landform restoration provided results that are consistent with field observations the simulation indicates that the entire landslide process lasted for 80 s and the sliding mass reached a maximum velocity of 64 m s the landslide formed a landslide dam with a length of 1900 m a width of 600 m and a depth of 200 m the simulation results show that the level of the riverbed at that the time of the landslide was at least 25 m higher than it is today on the combined basis of the simulation results and field observations the authors propose explanation that the following valley evolution sequence occurred after river blocking the landslide dam experienced flood overtopping and then was eroded until it had mostly had been transported away by river flow and the river then rapidly incised the bedrock to form the present day landform based on the field investigations the authors summarize the failure mechanism of steep inclined antidip rockslides and found that tectonics play an important role in the formation of landslide dams or trigger of landslides and the failure of landslide dams in an active tectonic environment of tibetan plateau

pore facies of smackover carbonate reservoirs in southwest alabama abstract pore facies are rock units that are defined by certain proportions of pore types contain specific pore throat size distributions and exhibit certain consequent fluid flow properties pore facies may contain only one pore type but more typically are characterized by a combination of several pore types data used in this study consist of point counts of thin sections that are plotted on ternary diagrams whose apices are pore types ternary pore plots commercial porosity and permeability data from core analyses qualitative thin section descriptions and qualitative core descriptions two distinct but partially intergrading pore facies are recognized in the smackover of southwestern alabama these pore facies are defined based on the two most common pore types in the smackover particle moldic including secondary intraparticle and intercrystalline pores which together account for greater than 85 of total porosity in the smackover rocks assigned to the moldic pore facies exhibit similar depositional fabrics and experienced similar diagenetic processes for example this pore facies is most commonly composed of peloid and ooid grainstone some fabric selectively dolomitized modified by early cementation and particle dissolution by contrast in the intercrystalline pore facies destruction of primary fabrics by nonfabric selective dolomitization is almost the sole determinant of pore system characteristics the moldic pore facies dominates to the northwest choctaw western clarke washington counties the updip area and the intercrystalline pore facies is dominant to the south and east mobile monroe baldwin escambia and conecuh counties the downdip area pore facies distributions overlap in some areas e g western monroe county indicating that multiple pore facies occur in many smackover fields the two pore facies exhibit substantially different petrophysical characteristics the mean slope of regression lines of porosity on ln natural log permeability for the intercrystalline pore facies is 0 47 with a range of 0 19 to 0 90 the mean slope for the moldic pore facies is 0 22 with a range of 0 18 to 0 27 the higher slopes for the intercrystalline pore facies mean that permeability values may be more precisely predicted from porosity data in this pore facies the mean maximum permeability for the intercrystalline pore facies is 130 md the corresponding value is 91 md for the moldic pore facies high permeability fluid conduits are more common in the intercrystalline pore facies than in the moldic pore facies in addition all high permeability examples of the moldic pore facies contain substantial amounts of interparticle porosity and are found near the smackover subcrop the remainder of the moldic pore facies is characterized by permeability values substantially less than those of the intercrystalline pore facies porosity values are commonly higher in the moldic pore facies which has a range of mean porosity of 10 2 to 28 0 compared to 9 6 to 20 5 for the intercrystalline pore facies greater hydrocarbon volumes can be stored in reservoirs dominated by the moldic pore facies but connectivity is better in the intercrystalline pore facies mixtures between the two pore facies are moderately common mixed pore systems commonly resemble the intercrys talline pore facies in the slope of the regression line of porosity on ln permeability in strata with mixed pore systems isolated particle moldic pores are commonly connected by networks of intercrystalline pores which control transport of fluids out of particle moldic pores

evidence of episodically accelerated denudation on the tibetan namche barwa massif by megafloods abstract megafloods cause widespread mobilization of sediments that have strong potential to control the geodynamic evolution of the namche barwa nb massif by changing the landscape morphology within a short time however the impact of catastrophic events on the denudation of the massif over the longer time scale has not been explored in detail this contribution assesses the impact of catastrophic floods on the denudation style of the namche barwa nb massif over millennial time scales towards this 21 optical ages and 1700 detrital thermochronometric ages of zircon and apatite minerals extracted from paleoflood sediments downstream of the massif were integrated with decadal sediment load and aggradation data to estimate the minimum denudation rate during paleoflood events the results indicate that the 7 ka flood eroded 71 m of material from the nb massif this denudation is equivalent to the material that would be produced over 8000 years of erosion at a rate of 9 mm a the 3 5 ka flood eroded 24 m of material equaling 2500 years worth of erosion at a rate of 9 mm a such relatively instantaneous denudations are three orders of magnitude higher than averaged denudation rates over million year time scale this study therefore provides the first evidence of the strong interplay of catastrophic flood events and tectonics for the rapid exhumation of the namche barwa massif megafloods from the failure of dammed lakes provide valuable information to understand the flood surge risk for human settlements in the siang and the assam valleys

the influence of large landslides on river incision in a transient landscape eastern margin of the tibetan plateau sichuan china deep landscape dissection by the dadu and yalong rivers on the eastern margin of the tibetan plateau has produced high relief narrow river gorges and threshold hillslopes that frequently experience large landslides large landslides inundate river valleys and overwhelm channels with large volumes 10 5 m 3 of coarse material commonly forming stable landslide dams that trigger extensive and prolonged aggradation upstream these observations suggest that strong feedbacks among hillslope processes channel morphology and incision rate are prevalent throughout this landscape and are likely characteristic of transient landscapes experiencing large increases in local relief in general landslide effects are a by product of rapid incision initiated by regional uplift however over timescales relevant to landscape evolution 10 4 yr large landslides can also act as a primary control on channel morphology and longitudinal river profiles inhibiting incision and further preventing the complete adjustment of rivers to regional tectonic climatic and lithologic forcing we explore a probabilistic numerical model to provide a quantitative framework for evaluating how landslides influence bedrock river incision and landscape evolution the time average number of landslide dams along a river course and thus the magnitude of the landslide influence is set by two fundamental timescales the time it takes to erode landslide deposits and erase individual dams and the recurrence interval of large landslides that lead to stable dams stable gradually eroding landslide dams create mixed bedrock alluvial channels with spatial and temporal variations in incision ultimately slowing long term rates of river incision thereby reducing the total amount of incision occurring over a given length of river a stronger landslide effect implies that a higher percentage of channel length is buried by landslide related sediment leading to reduced river incision efficiency the longer it takes a river channel to incise into a landslide dam and remove all landslide related sediment the more control these events have on the evolution of the river profile and landscape evolution this can be the result of slow erosion of stable dams or a higher frequency of large events

the 2000 yigong landslide tibetan plateau rockslide dammed lake and outburst flood review remote sensing analysis and process modelling abstract in april 2000 a large scale rock avalanche dammed the yigong zangpo river forming an extensive rockslide dammed lake the impoundment lasted for 62 days before a catastrophic breaching caused a massive outburst flood in the yarlung zangpo tibet and the dihang rivers india that travelled downstream to the main floodplain of the brahmaputra in northeastern india in response to discrepancies in the published literature on the event we present a review and re evaluation of the characteristics of the rock avalanche and associated landslide dammed lake we use digital topographical data srtm 3 and dynamic landslide modelling dan w and dan3d to determine the salient characteristics of the damming landslide and to characterise its behaviour our analysis indicates that the volume of the damming rockslide was ca 115 mm3 including 91 mm3 from the initial rockslope failure bulked during disaggregation to 109 mm3 and 6 mm3 from entrainment during its 10 1 km travel down zhamulong gully the debris travelled with an average velocity of 15 18 m s and resulted in a landslide dam on the yigong river with a minimum height of about 55 m using landsat 7 imagery obtained before during and after impoundment in conjunction with an srtm 3 dem we reproduced the filling of the lake we determine that the landslide dam formed an extensive reservoir with an impounded volume of 2 015 gm3 and a maximum possible lake level of 2264 m asl rounded to 2265 m asl our figures differ from those previously published but are believed to be well constrained verifiable estimates of the volumes of the 2000 yigong events the outburst occurred after an attempt by army personnel to manually dig a spillway over the landslide debris and resulted in the entire volume of the lake draining in about 12 h the outburst flood travelled over 500 km south into india with a recorded rise in river level of 5 5 m at the pasighat gauging station 462 km downstream in terms of historical outburst volumes from rockslide dammed lakes the volume of the 2000 yigong event is only exceeded by that of the 1841 outburst flood from the indus river rockslide dammed lake northern pakistan

large rock avalanches triggered by the m 7 9 denali fault alaska earthquake of 3 november 2002 the moment magnitude m 7 9 denali fault alaska earthquake of 3 november 2002 triggered thousands of landslides primarily rock falls and rock slides that ranged in volume from rock falls of a few cubic meters to rock avalanches having volumes as great as 20 10 6 m 3 the pattern of landsliding was unusual the number and concentration of triggered slides was much less than expected for an earthquake of this magnitude and the landslides were concentrated in a narrow zone about 30 km wide that straddled the fault rupture zone over its entire 300 km length despite the overall sparse landslide concentration the earthquake triggered several large rock avalanches that clustered along the western third of the rupture zone where acceleration levels and ground shaking frequencies are thought to have been the highest inferences about near field strong shaking characteristics drawn from interpretation of the landslide distribution are strikingly consistent with results of recent inversion modeling that indicate that high frequency energy generation was greatest in the western part of the fault rupture zone and decreased markedly to the east d 2005 elsevier b v all rights reserved

back analysis of the draining process of the tangjiashan barrier lake abstractthis study attempts to use a dam breach model to reproduce the well monitored outflow hydrograph obtained during the dam breaching process of the tangjiashan barrier lake which was formed by a landslide triggered by the wenchuan earthquake on may 12 2008 in china the key parameters that affect the model results such as soil erosion and breach lateral enlargement are reviewed by using field measurements followed by extensive sensitivity studies the present paper advocates a hyperbolic model for soil erosion rate and a circular slip surface approach for breach lateral enlargement which contribute to more reliable model results the governing equations are solved using a numerical method that allows straightforward calculations coded in an excel 2007 spreadsheet this provides an easy transparent and robust tool that could enable practicing engineers to perform dam breach analyses with a comprehensive understanding of the uncertainties involved this back analysis confirms that the peak outf

barrier lake bursting and flood routing in the yarlung tsangpo grand canyon in october 2018 abstract ice soil mixture landslide dams formed frequently in the tibetan plateau in response to global warming which pose great threats to both upstream and downstream areas due to inundation and lake bursting on 17 october 2018 a large landslide induced by an ice avalanche at the sedongpu basin of the yarlung tsangpo blocked the main course of the river near gyalha the barrier lake level rose quickly and the dam was overtopped naturally at 13 30 on 19 october 2018 generating a dam breaching flood with a peak flow rate of 32 000 m3 s this paper presents a comprehensive study of the disaster chain of landslide barrier lake dam breaching river flooding in the yarlung tsangpo grand canyon detailed geological and hydrological characteristics of the study region rapid prediction of the dam breaching hydrograph using an erosion based numerical model and analysis of the flood routing in a 460 km canyon reach along the yarlung tsangpo the simulated peak discharge at the dam site is over 30 000 m3 s and the corresponding dam breaching and flood routing hydrographs agree well with the observations two additional scenarios with larger inflow rates are also considered results show that with a larger inflow into the barrier lake the erosion of the dam body becomes more rapid when the inflow rate is increased by six times the peak dam breaching discharge can be doubled the study serves as basis to manage the flood risks due to landslide dam bursting on the yarlung tsangpo or similar rivers

the last interglacial stage definitions and marine highstand north america and eurasia abstract delineation of the boundary between the last interglacial lig and the last wisconsinan glacial stage in north america represents a critical yet unresolved issue subdivisions of the late pleistocene are based on oxygen isotope ice cover and pollen stratigraphic data boundaries defined by isotope chronology hinge on complex interrelationships between 18o in foraminifer tests ice volumes stored on land and coeval sea level position in the absence of adequate pollen stratigraphic documentation pleistocene subdivision boundaries were harder to establish in north america than in europe time transgressive pollen zones revealed increased lengths of the climatically floristically defined lig from the european subarctic to the mediterranean conflicting definitions of sangamon as representing only the last interglacial of minimum ice cover and higher temperatures or broadly defined sensu lato also incorporating early part of the last wisconsinan glacial stage persist in the north american literature the exclusively interglacial age of the sangamon geosol originally used in dating the sangamonian stage proved untenable designation of an eowisconsinan interval corresponding to susbtages mis 5d a also lacks merit despite climate and vegetation related discrepancies pollen and coastal deposit based comparisons between europe and north america during mis 5 and the holocene are useful in establishing the climate history of the north american sangamonian and subsequent early wisconsinan substages an overarching mis 5 cooling trend represented by scattered subarctic and high mountain ice accumulation events followed the mis 5e eemian sangamonian temperature peak adoption of the general european practice that asymmetrically splits mis 5 into a short mis 5e interglacial and a long early wisconsinan glacial mis 5d a interval is preferred in north america as well subdivisions in the normalized 18o curve that serve as the chronological framework and the wealth of european pollen data support this approach while multiple pre sangamon pleistocene marine paralic intervals do occur on the nw gulf coast all pre sangamon pleistocene marine and brackish inshore deposits had been removed by erosion in the ne coastal plain a single inshore nearshore marine sediment and highstand interval is well documented in this region the lig highstand sequence correlates with varied eemian marine and paralic mis 5e deposits encountered along northern and western european siberian and additional shores apart from reliably dated sangamonian s florida coral reefs identification and dating of lig highstand deposits remain highly problematical in se atlantic shore terraces

dynamics mobility controlling factors and transport mechanisms of rapid long runout rock avalanches in china abstract the dynamics and occurrence conditions of 43 rapid and long run out rock avalanches in china were summarized their dynamics were classified into 5 types the standard dynamic type was designated to be fail squirt and flow where part of the landslide path always has a parabolic airborne course because the slide body has an initial speed and the toe of the surface of rupture projects the landslide into the air the occurrence conditions of rock avalanches of the standard dynamic type are huge kinetic energy elevated toe to the surface of rupture and enough transport space to run out into the occurrence conditions of the other four types were then compared with the standard dynamic type statistical analysis showed that volume topography huge kinetic energy and an elevated toe to the surface of rupture were the principal factors controlling mobility in the rock avalanches four of the rapid long run out rock avalanches each in a different geological setting were then examined in more detail to reveal the transport mechanisms leading to their high speed and long runout the results suggested that besides their huge kinetic energy high pore water pressure produced by undrained shear and elastic energy released by grain fragmentation were the main transport mechanisms contributing to the long travel distances and high speeds of rock avalanches field investigation indicated that air was involved during the transport but whether it influenced the transport or how much the influence was is still much disputed

long runout mechanism and landsliding behaviour of large catastrophic landslide triggered by heavy rainfall in guanling guizhou china a large catastrophic landslide was triggered by a heavy rainfall on 28 june 2010 in guanling guizhou china the landslide buried two villages and killed 99 people along the runout path the lands

the evolution 2010 2015 and engineering mitigation of a rockslide dammed lake hunza river pakistan characterisation by analytical remote sensing abstract the remnants of rockslide dams are widespread in the deeply incised river valleys of the northwest himalayas and adjacent pamir mountains of central asia in january 2010 a major rockslide estimated volume 55 mm3 dammed the hunza river nw pakistan and a rockslide dammed lake lake gojal immediately began to form the lake overtopped the rockslide dam 145 days later through a spillway excavated in the surface of the debris by pakistan authorities lake gojal successively reduced in volume in response to spillway widening and deepening in engineering works up to may 2013 on august 28 2015 day 2063 of impoundment a remnant lake still remains using srtm 3 arc second digital terrain data and ten high resolution satellite images from the period march 2010 august 2015 we document the river damming environment of the attabad rockslide track and quantify the development of rockslide dammed lake gojal and calculate lake areas and volumes at various stages of filling stable overtopping and partial draining to a final stable configuration we introduce a method of delimiting lake shorelines by a pixel method which produces a mean elevation surface in the srtm dem this technique results in accurate estimates of shoreline elevation and corresponding lake areas and volumes we estimate the maximum volume reached by lake gojal 51 days after overtopping to have been approximately 455 mm3 using this data we also evaluate the mitigation works carried out by pakistan authorities and find that i they achieved an initial reduction of about 26 in the maximum possible volume of lake gojal that would have been reached without engineering intervention and ii as of august 28 2015 in drawing down the lake by 40 m they had achieved a 72 reduction in the maximum volume reached by lake gojal after overtopping without a catastrophic release taking place the emplacement of rockslide dams and the behaviour of their impounded lakes are critical hazards to communities and the development of infrastructure including hydroelectric facilities in this region of central asia we show that a combination of high resolution optical satellite imagery and srtm 3 arc second digital topography is very effective in producing key first order data on rockslide dammed lakes for geomorphic and hydrological analysis as well as the evaluation of engineering mitigation

the gigantic seymareh saidmarreh rock avalanche zagros fold thrust belt iran the seymareh rock avalanche first described by j v harrison and n l falcon in the 1930s is the largest known subaerial non volcanic landslide on earth the volume of its debris 44 gm 3 is approximately equal to that of the largest known subaerial landslide of any kind the 100 ka collapse of mount shasta volcano 45 gm 3 and approaches those of gigantic landslides on mars using satellite imagery srtm 3 data and detailed field investigations we gain a new understanding of the gigantic rock avalanche the initial failure 38 gm 3 involving a dip slope consisting of a relatively weak interbedded limestone mudrock sequence capped by resistant asmari limestone had an average thickness of 410 m along a 15 5 km width of the kabir kuh anticline the rockslide transformed into a rock avalanche that travelled 19 0 km with a fahrboschung the angle between the highest point of the pre landslide source area topography and the distal limit of the debris of only 3 6 initial failure involved complex planar sliding dictated by four structural elements 1 bedding parallel shears and 2 across bedding break throughs combined to produce a low angle 11 overall sliding surface that 3 broke out through the asmari carapace at the toe of the failed slope while 4 tectonically weakened bedding normal joints provided lateral release surfaces nine discrete bedding parallel basal sliding surfaces divided the detached mass into nine stacked plates the upper plate 23 gm 3 included 20 7 gm 3 of asmari limestone analysis of accelerator mass spectrometry radiocarbon dates from this study and by others indicates that the rock avalanche occurred between c 8710 and 9800 14 c years bp supplementary material a summary of the tectonics stratigraphy and physiography of the zagros fold thrust belt together with a description of surficial gravity collapse structures in the region harrison falcon 1934 1936 is available at www geolsoc org uk sup18612

riverbank stability analysis i theory in this paper a slope stability analysis for steep banks is used in conjunction with a method to calculate lateral erosion distance to predict bank stability response to lateral erosion or bed degradation the failure plane angle failure block width and volume of failed material per unit channel length may be calculated for the critical case these parameters define the bank geometry following failure and form the starting point for subsequent analyses the calculation procedure is illustrated by a worked example following mass failure slump debris accumulates at the bank toe the debris is removed by lateral erosion prior to further oversteepening or degradation generating further mass failures any process based model for channel width adjustment must account for the combined effects of lateral erosion and mass instability in producing bank instability the approach adopted here represents a marked improvement over earlier work which does not account for changes in bank geometry due to lateral er