river damming late quaternary rockslides in the otz valley region tyrol austria abstract the otz valley and adjacent regions in tyrol austria have been repeatedly affected by large rockslope failures following deglaciation six rockslides each over 107 m3 in volume were emplaced into the otz and inn valleys five of which formed persistent rockslide dams even though catastrophic rockslope failures are short lived events commonly minutes they can have long lasting impacts on the landscape for example large fans have built in the otz valley and knickpoints persist at the former dam sites even though the otz river has eroded through the deposits during the past thousands of years exact age constraints of rockslide dam failure however are still scarce empirical geomorphic stability indices from the literature successfully identified the least and the most stable dams of this group whereas the rest remain inconclusive with some indices variably placing the dams in the stable unstable and uncertain categories this shows a that further index calibrations and b better age constraints on dam formation and failure are needed and c that the exact processes of dam failure are not always trivial to pinpoint for ancient partially breached dams this study is a contribution towards better constraining the nature and landscape impact of dam formation following large rockslope failures

long runout rockslide on glacier at tsar mountain canadian rocky mountains potential triggers seismic and glaciological implications a rhomboidal shaped rockslide with a length of 2 2 km and an area of 1 35 km2 covers 30 of a small clemenceau icefield group cirque glacier by means of remote sensing airborne photography climate and seismic data analysis the extent timing possible trigger mechanisms and rockslide effects on the glacier are discussed an ml 2 0 seismic event on 14 september 2000 represents the rockslide and has a spindle shaped waveform and high energy in the low frequencies based on a strong signal duration of 56 108 seconds the rockslide had an average runout velocity of 22 45 m s 1 stress fatigue and a combination of rain and snow followed by rapid melt and night time freezing could have co triggered the slide additional seismic events with epicentres 40 km from the cirque were recorded 26 times since 1985 and range between ml 0 9 3 3 but none were caused by or triggered large mass movement with a rock source volume of 1 6 106 m3 and a deposited volume of 2 4 106 m3 the sum of bulking and entrainment is between 25 and 150 five melt seasons post event levees 20 30 m wide tower 30 m over the surrounding glacier rockslide characteristics and its fahrboschung of 15 height length h l 0 28 indicate that this rockslide is quite typical for long runout rockslides on glaciers however the basal friction coefficient was higher than found on other glaciers and could relate to the presence of medial moraines transverse to the flowline and to pre slide debris cover the difference between the coefficient of friction in the main flowline 0 11 0 14 and that in a lobe confined between two medial moraines 0 065 suggests that confinement increases mobility by 70 115 apart from reduced ablation under the rock debris effects of the rockslide on the glacier were minimal copyright 2010 john wiley sons ltd

using relative sea level data to constrain the deglacial and holocene history of southern greenland this paper presents new holocene relative sea level rsl data collected from isolation basins close to the town of paamiut in south west greenland the data shows a rapid fall from a marine limit of c 52 m asl at c 10 9 cal ka bp to close to present by c 9 5 cal ka bp at rates of up to c 32 mm yr falling below present for the majority of the holocene before rising to present in the last 2000 years the elevation of the rsl lowstand is not well constrained but was at least below 3 m this pattern of rapid rsl fall during the early holocene matches the pattern seen at other southern greenland locations suggesting rapid largely simultaneous ice retreat from the area surrounding the qassimiut lobe at the start of the holocene occurring c 2000 years after the initial deglaciation of the extreme southern tip of greenland the rsl histories from this and other southern greenland locations are distinct to those recorded further north along the west coast and are in broad agreement with a pattern of vertical land motion and rsl predicted by the huy2 model simpson et al 2009 which predicts an 80 m drop in the contribution of vertical land motion to rsl at 10 cal ka bp between sisimiut and paamiut on the west coast despite this broad scale spatial agreement between the rsl data and the huy2 model it fails to satisfactorily predict the holocene rsl histories at paamiut and other southern greenland locations sensitivity tests indicate that the data model misfits are most likely due to an over estimate of the forcing during the holocene thermal maximum or the response to this forcing in southern greenland and error in the north american ice sheets component of the background deglaciation model our new data suggests that much of the southern part of the ice sheet acted differently to the area further north however rsl changes at paamiut are also largely impacted by regional and larger scale processes including a bulls eye of uplift centred on the west the impact of the holocene thermal maximum and the influence of the collapse of the north american ice sheets

rock fall hazard assessment in asar hill ancient mabolla city mugla sw turkey this paper discusses the potential rock fall hazard of asar hill this flat topped hill containing upper miocene conglomerate and finer grained sedimentary rocks hosts to the ancient mabolla city the seasonal temperature differences are high in this rainy region block sizes bed and joints attitudes were measured along three profiles during field study schmidt hammer was applied to grains and matrix of conglomerates for determining strength in situ one joint set in profile a 3 in profile b and 4 in profile c were determined via dips analysis an intersection of joints and bedding directed 25 35 nw caused the block formation control slope angle and mass movement type at least 10 blocks 0 6 1241 085 tons were fixed on top of profiles two blocks on top of the eastern profile a contain archaeological ruins after back analysis for determining restitution coefficients rocfall version 4 9 software program was used to determine possible end points of those blocks most of the blocks can reach the valley and pass the other side which includes settlements and gardens consequently the possible rock fall hazard in asar hill is threatening visitors and settlers the cleaning of detached blocks on top of slope is one of the easiest ways however in situ preservation of blocks with archaeological ruins via tensioned rock anchors and or patterned rock bolts has vital importance relocation of settlers and gardens opening trench around hill and establishing green belt forest would be considered as other measures

monitoring numerical modelling and hazard mitigation of the moscardo landslide eastern italian alps abstract the moscardo torrent basin eastern italian alps is a high risk site since a large roto translational landslide might dam the torrent with the consequence of increasing the possibility of large debris flow events creating a threat for the infrastructures and the socio economic activities of the villages that dot the valley below the landslide whose volume is estimated 2 million m3 has been monitored since 2006 with inclinometers electric piezometers and a gps network the velocity along the entire body of the landslide averages 1 0 1 5 cm per month the shear surface develops at depths varying from 9 to 10 m to 55 62 m while the groundwater table is almost constant throughout the year despite a cumulative rainfall of the area that usually reaches 2000 mm year the movements were simulated in a numerical model in order to estimate the stabilization effect obtained by different types of possible countermeasures the simulation was carried out using flac 2d with creep modelling visco elasto plastic model of the medium in the sliding zone was assumed allowing to determine the relation between time and displacement a 10 year displacement trend starting from the initial situation of 2006 was simulated moreover seismic conditions were taken into consideration with a quasi static approach by applying a horizontal acceleration the numerical model was built and validated on the basis of the data retrieved from geological investigations as well as from inclinometric and gps measurements the results show that an accurate and well planned multidisciplinary approach can help the decision makers in the choice of the most effective engineering solution for the mitigation of landslide hazard and risk

cement stratigraphy of pennsylvanian holder formation sacramento mountains new mexico cyclic strata of the holder formation virgilian new mexico were deposited across a pennsylvanian shelf to basin transition during a time when sea level fluctuated over tens of meters cement stratigraphy studies indicate abundant calcite precipitation from low temperature fresh water within shelf shelf crest and shelf edge marine limestones freshwater cementation occurred during 15 periods of intraformational subaerial exposure these early cements are least abundant in basin and lagoon limestones the distribution of the early cement zones suggests that cementation was controlled by paleotopography stratigraphic position below subaerial exposure surfaces lithology and configuration of the paleoaquifer system distribution of early calcite cements provides new data for interpretation of cycles diagenetic systems and porosity evolution in petroleum reservoirs trace element analyses support a low temperature freshwater origin for the early cements cement stratigraphy studies fluid inclusion analyses and trace element analyses indicate a later cement that occluded remaining limestone porosity precipitated from a sodium and calcium rich brine at a temperature of about 100 c stratigraphic reconstruction dates this cementation as cretaceous or later fluorescent oil filled fluid inclusions were trapped along fractures in the late cement indicating oil migration during or after late stage cementation

numerical analysis of initiation and progressive failure in natural rock slopes the 1991 randa rockslide the 1991 randa rockslide in the swiss alps involved several complex mechanisms relating to geological mechanical and hydrological processes for which no clear trigger can be asserted this paper investigates the concept of progressive failure and the numerical modelling of rock mass strength degradation in natural rock slopes using the randa rockslide as a working example results from continuum i e finite element modelling are presented to illustrate a hypothesis suggesting that initiation of a progressive rock mass degradation process ultimately leading to failure began following deglaciation of the valley below discontinuum distinct element modelling is then applied to investigate the underlying mechanisms contributing to the episodic nature of the rockslide finally the use of a hybrid method that combines both continuum and discontinuum techniques to model fracture propagation are discussed in the context of modelling progressive slide surface development linking initiation and degradation to eventual catastrophic failure

analyses of past and present rock slope instabilities in a fjord valley implications for hazard estimations abstract for quantitative hazard assessment it is necessary to define the magnitude frequency distribution and a temporal model of the landslide frequency this is often complicated for large rock slope failures due to the lack of significant numbers of large rock slope failures in inventories of a given homogeneous region or sparse information about the timing an inventory of 108 rock slope failure deposits within the fjords of the storfjord region including a relative rockslide chronostratigraphy was available for this study the temporal distribution of rock slope failures is characterized by a rapid response with a high frequency of failures directly after deglaciation followed by a lower constant frequency since 9 000 years bp for the entire storfjord region the largest recorded volumes failed directly after deglaciation volumes larger than 5 10 6 m 3 have not been recorded within the last 9 000 years in addition 17 rockslide scars and on the other hand 17 potential rock slope instabilities have been mapped at the northeastern flank of tafjord which is a branch of the storfjord volume frequency relations have been developed for the three inventories from tafjord comprising i fjord deposits ii rockslide scars and iii potential instabilities they result in very similar distributions over the entire volume range all three inventories are underlying the same processes that lead to destabilisation and finally failure additionally the compilation of the three inventories is independent and based on different methodologies the similarity of the volume frequency distributions is thus verifying the different inventories hence the obtained volume frequency relation can be used to assess the rockslide hazard for the study area present day annual expectable frequencies for different volume classes have been assessed based on the obtained volume frequency relation of the fjord deposits for example the average annual frequency for rock slope failures of v 1 10 6 m 3 originating from the northeastern flank of tafjord is 1 1670 based on a lognormal distribution this regional hazard can be used to improve previously existing qualitative susceptibility rankings for potential unstable rock slopes within the tafjord region the resulting probabilities are very low however the uncertainties of all hazard estimates are very high

diagenesis and sea level change lessons from moruroa french polynesia an inclined borehole through the margin of moruroa atoll french polynesia in which the ages of units are constrained by radiometric dates provides a unique opportunity to examine the relationship between sea level change and diagenetic history the oldest rocks encountered are dated at 355 840 yr bp and the overlying succession records five cycles of deposition and emergence culminating in the deposition of the holocene sequence successive intervals of emergence provided the driving force for diagenetic change promoting the through flow of chemically aggressive fresh waters that were at times either pervasive or confined within relatively isolated pathways on a millimetre to metre scale these locally varying flows and flow rates defined restricted zones characterized by differences in water chemistry and diagenetic signatures in contrast to some sequences elsewhere the upper part of the moruroa atoll succession is typified by alternations of intervals in which either several generations of cement growth are represented or only one or two cements are present three distinct diagenetic signatures can be recognized as follows i fresh water phreatic zones are reflected in neomorphism and the deposition of cements that occluded porosity thus preventing the deposition of later cements and conferring relative stability ii vadose zones are characterized by more complex diagenetic sequences reflecting multiple phases of dissolution and cement growth attesting to the relative duration of exposure and the conditions of ground water flow and iii deep in the core sequences reflect lowstand deposits that suffered sub sea diagenesis generating pores in which multi layered marine cements apparently formed at more frequent intervals than those subject to subaerial processes all cements appear to be of narrowly constrained ages these results highlight the contentious issue of whether the distributions of former diagenetic environments can be related to specific sea level stands and erosion surfaces it seems that in the moruroa core some cycles of sea level change are reflected in distinctive packages of diagenetic features that have not been overprinted by cement growths during later sea level stands

fluorescent bands in massive corals result from terrestrial fulvic acid inputs to nearshore zone the discovery of yellow green fluorescent bands in the skeletons of massive corals from inshore waters of the great barrier reef and the temporal and spatial correlations of these bands with adjacent river flow1 prompted an investigation into the substances responsible for the phenomenon we have determined that all regions of the coral skeleton contain fulvic acids2 3 which impart a blue background fluorescence the yellow green fluorescent bands found only in inshore coral appear to result from enhanced concentrations of low relative molecular mass 10 000 fulvic acids from adjacent river input these compounds are ubiquitous and the yellow green banding phenomenon can be expected to occur in massive corals located near to significant river systems in the widely distributed genus porites4 the great age of the largest colonies1 means that extremely long highly resolvable records of coastal runoff exist throughout tropical nearshore seas

planar lamellar substructures in quartz both single and multiple sets of lamellar features in quartz grains can be produced in shock experiments and are observed at known impact sites they can also be produced in static constant strain rate experiments and are observed at known tectonic and explosive volcanic sites the former are strictly planar and parallel and generally conform to rational crystallographic orientations in the quartz crystal structure the latter can also be planar and parallel but sometimes show slight to moderate curvature with lamellar bifurcations and variable lamellar widths their orientations show a variety of forms with in general a broader angular distribution than that of the impact generated lamellae deductions of physical conditions of deformation from optical morphology spacing multiplicity and orientation information alone remain somewhat conjectural full characterization by transmission electron microscopy tem appears to be necessary

surface exposure dating of the flims landslide graubunden switzerland abstract sixteen boulder and bedrock surfaces related to the flims landslide volume 8 12 km3 were dated with 36cl and 10be exposure ages range from 4900 250 yr to 15 440 1480 yr including corrections made due to snow cover and karst erosion ages of 11 410 590 yr and 13 340 1090 yr were obtained on bedrock surfaces outside of the landslide zone these are minima for deglaciation of segnes valley and provide constraints on possible amounts of inherited nuclides based on seven boulder ages which range from 8200 260 to 9520 990 yr a mean of 8900 700 years is calculated for the flims landslide we exclude three outliers one significantly older and two significantly younger than the others and the ages from the cassons bedrock site from the mean calculation the latter is excluded as shielding due to snow and vegetation cover is difficult to constrain there the oldest boulder on the landslide yielded an age 15440 1480 yr more than 5000 years older than any other boulder age suggesting that it included the surface of the pre slide bedrock the exposure ages are consistent with a single failure event the erratics and patches of till lying on the landslide debris must have been carried piggy back on top of the landslide rather than having been deposited by the late pleistocene vorderrhein glacier the flims rockslide is about the same age as the kofels 9800 yr and kandertal 9600 yr rockslides all three occurred during the marked transition to warmer wetter conditions during the early holocene

diagnostic characteristics and paleodynamics of supraglacial rock avalanches innerdalen western norway abstract misinterpretation of rock avalanche deposits in mountain environments is not uncommon because of the complex interactions between rock avalanches and glaciers this paper for the first time presents a detailed description of suspicious rock boulder deposits which are remnants of a rock avalanche onto a late pleistocene glacier the boulder deposits cover around 1 1 km 2 and are distributed over an area of around 7 5 km 2 and a variety of landforms three closely nested distinct terminal moraines 0 45 km 2 and dislocated terminal moraines 0 34 km 2 entirely built up of large boulders lateral moraines that decrease in elevation over a short distance and connect to the terminal moraines small patches 0 02 km 2 of boulders that occur in islands on a peat dominated valley floor and large patches of boulder fields 0 25 km 2 in size hanging 350 m above the valley floor the latter are disconnected from any potential source area 10 be cosmogenic nuclide ages of the three terminal moraines give an indistinguishable late pleistocene age of 13 6 1 4 ka whereas the largest boulder field that is located on the opposite side of the valley from the failed mountain yields a 10 be age of 14 1 0 4 ka which is slightly older but indistinguishable from the moraine deposits within uncertainty margins all boulder deposits add up to a volume of 31 10 6 m 3 the interpretation of a single rock avalanche source for those landforms is further confirmed by numerical runout modeling using dan3d a failure of the entire volume from skarfjellet mountain would result in a runout pattern that is identical to that of the distributed boulder fields when considering that the valley was filled with a glacier around 350 m thick the rock avalanche would not reach the position of the terminal moraines however a glacial re advance could have transported the boulders to that position the late pleistocene rock avalanche was followed by a holocene rock avalanche with a volume of 23 10 6 m 3 and a typical lobate deposit damming the innerdalen valley and creating a lake 10 be ages indicate that this event occurred 7 97 0 94 ka ago structural measurements performed on high resolution lidar scans show a strongly jointed source rock with three joint sets with dip dip direction 81 034 86 331 and 77 354 and a foliation with 22 003 the kinematic of the failures can thus be a combination of small scale wedge failures and planar sliding on shallow dipping foliation our detailed description can enable a better identification and interpretation of similar deposits in other mountain areas

10be and 26al production rates deduced from an instantaneous event within the dendro calibration curve the landslide of kofels otz valley austria surface exposure dating requires the knowledge of cosmogenic nuclide production rates when determining time integrated production rates the exposure ages of the calibration samples need to be accurately known the landslide of kofels austria is very well suited for this purpose it is the largest landslide in the crystalline alps of austria dating back to 7800 100 years bc ams 14c dating of buried wood which is well within the 14c dendro calibration curve exposed quartz veins were sampled from the tops of large boulders from the toe of the landslide for analysis of 10be and 26al to calculate sea level high geomagnetic latitude 60 open sky radionuclide production rates corrections were applied for altitude and latitude for shielding by surrounding mountains for sample geometry vegetation and snow cover and for sample thickness the production rates for an exposure age of 10 000 years are 5 75 0 24 10be atoms yr g sio2 and 37 4 1 9 26al atoms yr g sio2 a 26al 10be ratio of 6 52 0 43 can be calculated the influence of the geomagnetic field on these production rates has been estimated using two different geomagnetic field records our production rates should be a good approximation for the use of surface exposure dating between about 5000 and 13 000 years bp

static and dynamic simulation of a 700 m high rock slope in western norway abstract static and dynamic rock slope stability analyses were performed using a numerical discontinuum modelling technique for a 700 m high rock slope in western norway the rock slope has been investigated by the geological survey of norway ngu which has been carrying out rock slide studies for the county more and romsdal in western norway the purpose of numerical modelling was to estimate the volume of the rock mass that could potentially slide under static and dynamic forces this estimation was required to assess the run up heights tsunami in a fjord that could potentially be caused by the rockslide three cases have been simulated for predicting the behaviour of the rock slope first an initial static loading is applied in the numerical model to simulate the prevailing rock mass conditions at the site second saturated and weathered joint conditions are modelled by reducing the residual friction angle along the discontinuities of the rock mass in doing so the model simulates the effect of degradation of discontinuities in the rock slope third a dynamic loading based on peak ground accelerations expected in the area is applied to simulate dynamic earthquake conditions these numerical studies have provided some useful insights into the deformation mechanisms in the rock slope both sliding and rotation of blocks start to occur once the residual friction angle along the discontinuities is reduced and when the region is shaken by a strong earthquake the results indicate that due to variations in the inclination of discontinuities the entire slope does not become unstable and that down slope sliding and rotation of blocks occur mainly on the top layers of the slope within the range of parameter values considered for this study it is unlikely that the whole rock slope can be destabilised the study provides an illustration of how the geo mechanical properties of a rock mass can be integrated in a discontinuum rock slope model which is used for predicting the behaviour of the slope under existing environmental and earthquake conditions this model has helped not only to better understand the dynamics of the rockslide but also to estimate the potential rock volume that can become unstable when subjected to static and dynamic loads

numerical modelling of the gravity induced destabilization of a slope the example of the la clapiere landslide southern france abstract a finite difference two dimensional model with hooke mohr coulomb properties and topography derived from the dem are used to reproduce the la clapiere landslide the principal factor defining the gravity driven destabilization of the model is a gradual reduction in the cohesion this reduction simulates a degradation of the material properties with time because of weathering alteration processes the inelastic deformation fracturing and faulting first occur at mountain scale and results in normal fault formation causing crest sagging later the failure process is concentrated in the lower part of the slope and leads to the formation of a localized fault subparallel to the slope surface at a depth of ca 100 m this corresponds to the initiation of the la clapiere landslide and its propagation upslope a slow crest sagging continues during the whole model evolution

examples of multiple rock slope collapses from kofels otz valley austria and western norway abstract this paper describes the effects of large massive rock slope failures on subsequent slope stability three examples of large rock slope failures from the austrian alps and norway demonstrate that failure increases the probability of further collapses at kofels austria a holocene rock slope failure several km3 in size filled the otz valley the morphology of the deposits indicates that at least one subsequent failure occurred along the head scarp of the first failure most likely a slide of similar size debris of the second landslide slid over the older deposits forming the famous kofels frictionite at least three rock slope failures all of them in excess of 106 m3 occurred from the same mountainside within the last 6000 8000 years at tafjord in western norway the most recent of these failures in 1934 triggered a destructive tsunami five large failures with volumes 50 000m3 occurred at ramnefjell norway within 50 years two of them caused considerable damage and a large number of death due to the formation of destructive tsunamis two dimensional finite element models of rock slope stability before and after the kofels and tafjord landslides show that massive rock slope failures produce a irregular slopes parts of which are as steep or steeper than the slope before failure and which represent new zones of instability and b zones of weakness related to slow slope deformation and related cracking

kinematic evolution of fault ramps and its role in development of landslides and lakes in the northwestern argentine andes the quebrada del toro and quebrada de las conchas in the cordillera oriental of northwestern argentina are notable for repeated landsliding and damming of major drainages both areas correspond to displacement transfer zones along major thrust systems that developed during the neogene uplift of the central andes during this period displacement transfer zones were areas of subdued relief that localized where rivers cross the fault systems however neotectonic deformation converted the transfer zones into restraining bends along strike slip systems resulting in enhanced uplift at river crossings the antecedent streams responded by rapidly downcutting into the ascending hanging wall blocks producing precipitous local relief the extreme local relief that was controlled by the kinematic evolution of faulting in both areas provides an effective precondition for landsliding which may have been ultimately triggered by seismicity and gravitational failure aided by enhanced undercutting during past humid conditions

structural and lithological controls on large quaternary rock avalanches sturzstroms in arid northwestern argentina landsat thematic mapper tm analysis aerial photograph interpretation and field studies of the semiarid puna plateau adjacent eastern cordillera and sierras pampeanas of argentina lat 24 28 s have revealed the existence of at least 55 rock avalanche deposits with volumes larger than 10 6 m 3 that formed by the collapse of entire mountain fronts the spatial distribution of landslide deposits is not random but it clusters along mountain fronts bounded by active faults inspection in the field reveals five principal controls on the distribution of these events the source area of the rock avalanches has two topographic constraints 1 vertical relief contrasts between the breakaway zone and the mountain front must exceed a threshold of 400 m and 2 the slope inclinations must be steeper than 20 rock avalanches are restricted to three types of lithology granites low grade metamorphic rocks and coarse clastic sediments structural controls are very important rock avalanches are controlled by planar structures such as bedding planes exfoliation joints minor faults and cleavage that all dip toward the valley in addition major slide clusters occur along mountain fronts that underwent quaternary reverse fault reactivation of former transfer faults with strike slip kinematics the trigger mechanism for the majority of these landslides is interpreted to be seismic although the ages of some major slides are about 30 ka and they may correspond to a more humid interval in southern south america

the youngest big impact on earth deduced from geological and historical evidence the comparison of events that followed the great impact at the cretaceous tertiary boundary with those contained within the flood myths suggests an analogous cosmic cause this paper proposes that there is geological evidence to support this thesis which is also indicated by a careful analysis of the natural phenomena described in flood traditions the time the sites the cause the detailed course of the events and the consequences of this catastrophe can hope to be reconstructed

electron microscopy study of hyalomylonites evidence for frictional melting in landslides abstract hyalomylonites from langtang nepal and kofels otz valley austria were investigated by transmission electron microscopy tem the matrix is glassy at both localities rarely it is crystallized and devitrified to dendrites and skeletal microlites of plagioclase alkali feldspar and biotite the matrix is chemically heterogeneous with schlieren and formed by partial to almost complete melting of host rocks of granitic to granodioritic composition locally glasses with pure quartz plagioclase and alkalifeldspar composition were found from sio 2 glass minimum temperatures of 1520 c are estimated at both hyalomylonite localities melting appears to be the result of frictional heating on the gliding plane of a large landslide the host rocks were deformed in a brittle mode microstructures typical of plastic deformation at high temperatures are displayed by inclusions and were probably inherited from previous tectonic events

geological model of the aknes rockslide western norway abstract aknes is known as the most hazardous rockslide area in norway at present and is among the most investigated rockslides in the world representing an exceptional natural laboratory this study focuses on structural geology and the usage of geophysical methods to interpret and understand the structural geometry of the rockslide area the interpretations are further used to build a geological model of the site this is a large rockslide with an estimated volume of 35 40 million m 3 derron et al 2005 defined by a back scarp a basal shear zone at about 50 m depth and an interpreted toe zone where the sliding surface daylights the surface the rockslide is divided into four sub domains experiencing extension in the upper part and compression in the lower part structural mapping of the area indicates that the foliation of the gneiss plays an important role in the development of this rockslide the upper boundary zone of the rockslide is seen as a back scarp that is controlled by and parallel to the pre existing steep foliation planes where the foliation is not favourably orientated in regard to the extensional trend the back scarp follows a pre existing fracture set or forms a relay structure the foliation in the lower part dipping 30 to 35 to s sse seems to control the development of the basal sliding surface with its subordinate low angle trust surfaces which daylights at different levels the sliding surfaces are sub parallel to the topographic slope and are located along mica rich layers in the foliation geophysical surveys using ground penetrating radar gpr refraction seismic and 2d resistivity profiling give a coherent understanding of undulating basal sliding surface in the subsurface the geophysical surveys map the subsurface in great detail to a depth ranging from 30 40 m for gpr to approximately 125 m for refraction seismic and 2d resistivity profiling this gives a good control on the depth and lateral extent of the basal sliding surface and its subordinate low angle thrusts drill cores and borehole logging add important information with regard to geological understanding of the subsurface fracture frequency fault rock occurrences geophysical properties and groundwater conditions both in outcrops and or drill cores constrain the geometrical and kinematic model of aknes rockslide

numerical modeling of the june 17 2017 landslide and tsunami events in karrat fjord west greenland on june 17 2017 the western coast of greenland was the site of a tsunami which flooded several villages killing 4 people and destroying 11 houses in the village of nuugaatsiaq this tsunami was triggered by a subaerial landslide which occurred in a fjord 32 km ene of nuugaatsiaq this paper presents the numerical modeling of this landslide of sim 50 million hbox m 3 and of the tsunami propagation from its source to nuugaatsiaq the landslide is considered as a granular flow under gravity forces and the water waves generated are related to the displacement of the sea bottom the results obtained are similar in amplitude to our inferences from videos i e three water waves between 1 and 1 5 m arriving at nuugaatsiaq with a period of roughly 3 min and are also in general agreement with the amplitude 1 m resulting from deconvolution of oscillations recorded on a horizontal seismogram operating at nuugaatsiaq nuug according to the field survey performed by fritz et al egu general assembly conference abstracts vol 20 of egu general assembly conference abstracts p 18345 2018a on july 2017 a second mass next to the landslide is threatening karrat fjord a sensitivity study is realized on its volume with 2 7 14 and 38 million hbox m 3 reaching the sea the shape of the water waves is found to be independent of volume and linearity is observed between the volume and the water wave heights finally the orientation of the slide does not seem to influence either the period or the shape of the generated water waves

seismic signatures of landslides the 1990 brenda mine collapse and the 1965 hope rockslides abstract we present the well documented case of a 2 10 6 m 3 rockslide that was recorded by seismographs to distances of several hundred kilometers and might have entered the canadian catalog as a bona fide earthquake except for independent knowledge to the contrary motivated by the observation of this event we reexamined the seismograms associated with the 1965 hope slide in british columbia the largest known historical landslide in the canadian cordillera and conclude that these seismograms were the signatures of two rockslides and not of hypothetical tectonic earthquake triggers as previously suggested mathews and mctaggart 1969 wetmiller and evans 1989 these events raise the general question of differentiation between seismic signals from landslides and true earthquakes we suggest an lp sp discriminant as the most obvious although a resolvable mechanism solution may be even more convincing efficiency of energy conversion from potential to seismic is also a diagnostic aid and correlates well with the slope of the slide detachment surface

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

kinematics of an alpine retrogressive rockslide in the japanese alps the aresawa rockslide in the japanese alps experienced a partial collapse 5 10 105 m3 in 2004 followed by an accelerated downward movement of the head area rather than stabilization this paper discusses the kinematics of a retrogressive rockslide area and factors promoting slope instability subsequent to the 2004 collapse on the basis of geodetic surveys and meteorological observations from 2006 to 2010 the unstable area covers at least 2 3 104 m2 and consists of five active blocks the main blocks are separated from the stable rock slope by pre existing sackung features that follow the strike of the bedding plane shear zones below these sackung features have developed into slip planes potentially causing the next collapse in particular the propagation of a slip plane causing movement at 70 cm yr 1 in the head area is promoted by bidirectional movement it consists of slow dip slip movement in snow accumulating periods and rapid side slip movement in snow melting and snow free periods both of which occur on the same slip plane this bidirectional movement appears to result from the combination of a loss of lateral support by the 2004 event and the immature state of the slip plane the primary trigger of the acceleration in the unstable area is the stress release by the 2004 collapse in addition the presence of a potential slip plane below the sackung features also promotes slope instability suggesting that sackung features behind a rockslide area may predefine the new head scarp of a forthcoming collapse copyright 2012 john wiley sons ltd

effects of porosity and clay content on wave velocities in sandstones the ultrasonic compressional vp and shear vs velocities and first arrival peak amplitude ap were measured as functions of differential pressure to 50 mpa and to a state of saturation on 75 different sandstone samples with porosities ranging from 2 to 30 percent and volume clay content c ranging from 0 to 50 percent respectively both vp and vs were found to correlate linearly with porosity and clay content in shaly sandstones at confining pressure of 40 mpa and pore pressure of 1 0 mpa the best least squares fits to the velocity data are vp km s 5 59 6 93 2 18c and vs km s 3 52 4 91 1 89c deviations from these equations are less than 3 percent and 5 percent for vp and vs respectively the velocities of clean sandstones are significantly higher than those predicted by the above linear fits about 7 percent for vp and 11 percent for vs which indicates that a very small amount of clay 1 or a few percent of volume fraction significantly reduces the elastic moduli of sandstones for shaly

sedimentology of rock avalanche deposits case study and review abstract detailed sedimentological studies concerning different facies types and the factors influencing their development such as lithology topography substrates etc were carried out at the carbonate tschirgant rockslide rock avalanche deposit in the eastern alps of austria several depositional facies and sub facies have been identified at this and other sites by many researchers these facies are found throughout the debris regardless of depth or travel distance and result from highly heterogeneous stress distributions in time and space during emplacement one of the most important recent observations in terms of emplacement dynamics is that shear is not confined to the base but is distributed throughout the debris except the coarse carapace due to the preservation of source stratigraphy in these non turbulent mass movements any horizontal facies or grain size variations need to be regarded in context since they strongly depend on source stratigraphy and hence the spatial distribution of lithologies i e geological units of different mechanical properties for example some lithologies do not form a boulder carapace due to absence of large in situ blocks in the source rock mass however at tschirgant slight facies maturation with distance within the same lithology is observed i e clast fragmentation progresses to create the distinct facies characteristic grain size distribution only after some distance travelled these details are revealed through facies based sampling and analysis studies based on bulk sampling in some cases observed progressively reduced grain sizes with distance and depth which might be a function of added variations within different facies sampled together in this paper the wealth of observations on rockslide and rock avalanche sedimentology of the past decades is combined with a detailed case study of a lithologically relatively simple deposit to outline global and site specific depositional structures and facies with the aim to summarize review and refine the current state of knowledge on rock avalanche and rockslide emplacement processes

neotectonics and catastrophic failure of mountain fronts in the southern intra andean puna plateau argentina new cosmogenic nuclide exposure ages of rock avalanche deposits in front of sierra laguna blanca in the arid argentine puna plateau demonstrate the effects of westward propagation of reverse faulting and the influence of active faulting on slope oversteepening and subsequent gravitational collapse the 21 ne exposure ages of 8 superposed landslides with volumes 0 3 km 3 are between ca 150 and 430 ka and indicate an average recurrence interval of large gravitational mountain front failures of 27 5 k y for the ultimate 7 landslides landsliding did not occur after 150 ka along this sector of the sierra laguna blanca the termination of landsliding activity correlates with reverse fault propagation into the piedmont area of the sierra laguna blanca the exposure age of ca 130 ka of a tectonically uplifted terrace postdates initiation of fault activity in the piedmont region and the fault scarp height of 120 m indicates important continued uplift in the piedmont no further offsets occurred at the mountain front due to this lack of tectonic activity at the mountain front no further collapse has occurred indicating that in this environment catastrophic mountain front failure is mainly controlled by tectonically driven slope oversteepening

subaqueous rock avalanche deposits exposed by post glacial isostatic rebound innfjorddalen western norway abstract this paper presents a detailed description of deposits and landforms of multiple rock avalanches in western norway one of which fell onto water saturated sediments in innfjorddalen below the former water level deposits of the latter are now exposed on the valley floor due to post glacial isostatic rebound at least three rock avalanches from the same source at grafonnfjellet mountain have occurred during late glacial and post glacial time and their deposits are distributed over an area of 1 44 km 2 in the valley these rock avalanches have volumes of 15 1 10 6 m 3 5 4 10 6 m 3 and 0 3 10 6 m 3 and yielded cosmogenic radionuclide 10 be ages of 14 3 1 4 ka 8 79 0 94 ka and 1 028 0 380 ka respectively the youngest event dates within uncertainty limits to a historic rock avalanche in the year 1611 12 ce the rock avalanches formed a stratified succession of deposits the rock avalanche deposits 1 38 m 2 have lobate forms have frontal rims and parallel ridges extend across the valley floor and up the opposite slope and form dams on the valley floor isolated hills comprised of rock boulders 0 61 km 2 interpreted to be toma hills are disconnected from the main rock avalanche deposits by a 520 m wide zone of deformed valley fill sediments trenches and a ground penetrating radar survey of these deposits indicate large scale deformation or liquefaction numerical runout modeling of the rock avalanches with the code dan3d supports the interpretation of their landforms and sources and highlights their runout behavior

low limit of mn2 activated cathodoluminescence of calcite state of the art in the literature the lower limit for mn2 activated cathodoluminescence cl of calcite is variously reputed to over a very wide range of values above 10 ppm mn our spectroscopic investigations of the cl response in natural calcite reveal that below 10 ppm manganese content mn2 activation is also present using the quantitative high resolution spectral analysis of cl qhrs cl an activation by mn2 in the range of 700 ppb is proved which cannot be determined visually so if not quenched the minimum mn2 content for mn2 activation is one atom in the irradiated calcite crystal lattice volume as the intrinsic background blue luminescence is used to determine non altered biogenic calcite the limit of mn2 activation plays an important role in the interpretation of diagenetic processes our results of spectroscopic analyses require a revision of current opinions about the diagenesis of calcite as revealed by cl investigation

sea level and diagenesis a case study on pleistocene beaches whalebone bay bermuda pleistocene fluctuations of sea level have left marine and aeolian limestones intercalated with glacial red soils on the bermuda carbonate platform atlantic 64 50 w 32 20 n successive eustatic highstands of similar amplitude drowned the tectonically stable platform and piled up similar sets of sediments up to three pleistocene beaches are stacked in shorelines sections post depositional diagenetic histories of these beaches can be linked to repeated changes in sea level and pore waters

cathodoluminescence in quaternary carbonate deposits abstract the cathodoluminescent oscillatory and sectoral growth zones common in crystals formed in ancient limestone successions in a variety of putative environments appear to be rare or absent from recent and pleistocene marine carbonate sequences the factors controlling cathodoluminescence and reasons for this disparity are examined the cathodoluminescent zones in the cements of ancient rocks have been interpreted as responses to variations in the redox potential of formative pore waters during crystal growth although similar cathodoluminescent behaviour is recorded from some deposits including travertines and quaternary speleothems formed in what are thought to have been strongly oxidizing environments the apparent absence of cathodoluminescence in the most recent and pleistocene marine deposits that presumably reflect deposition and diagenesis in environments that are also characteristically oxidized therefore seems anomalous the controlling influences on cathodoluminescence are reviewed together with evidence relating to observations of pleistocene marine deposits and likely conditions of formation but where it is present the mechanism s for its development remain elusive

why did the 1756 tjellefonna rockslide occur a back analysis of the largest historic rockslide in norway abstract on 22 february 1756 the largest historically recorded rockslide in norway took place at tjelle in the langfjord western norway the rockslide created three displacement waves of up to 50 m in height that caused 32 casualties and destroyed most houses and boats along the shores of the langfjord the trigger and contributing factors leading to the tjellefonna rockslide are largely unknown and even seismic triggering has previously been suggested this study provides a thorough back analysis of the tjellefonna rockslide using detailed geomorphological engineering geological and tectonic field mapping in combination with topographic reconstructions bathymetry analysis volume estimations and numerical slope stability analysis the back scarp and eastern flank of the tjellefonna scar form several tens of meter high rock walls while the basal failure surface and other parts of the scar are covered by rock avalanche debris that extend from the back scarp down to the bottom of the langfjord the rockslide occurred in granodioritic gneisses with variably developed metamorphic foliation that is folded and strike parallel to the fjord two prominent fault zones are present in close proximity to the tjellefonna scar one is steeply se dipping tjelle fault while the other one is sub horizontal to shallow se dipping ritlehamran fault both fault zones are linked to the more trondelag fault complex with one of its branches forming the langfjord lineament and probably also the faults at tjellefonna additionally there are four persistent joint sets that together with the metamorphic foliation and the tjelle fault define the back scarp of the rockslide and give a fracturing of the rock mass corresponding to a geological strength index gsi of 45 55 the gsi decreases significantly to 10 20 in the fault zones which form distinct weakness zones in the rock slope volume estimates based on a reconstruction of the ante rockslide topography range from 9 3 to 10 4 million m 3 which is lower than previous volume estimates 12 15 million m 3 large portions of the failed rock mass remained on land and only approximately 3 9 million m 3 entered the fjord the observed discontinuities in the rock mass at tjellefonna do not allow for a simple kinematic failure mechanism due to the lack of moderately se dipping structures the basal failure surface was most likely not composed of a single structure but of a complex interplay of fault zones metamorphic foliation joints and broken rock bridges numerical slope stability modelling highlights that weak fault zones are essential for the development of the failure surface over a long time this progressive failure was likely aided by low to medium magnitude earthquakes that are frequent in the region numerical slope stability modelling and historical accounts suggest however that heavy long lasting rainfall was the triggering factor for the 1756 tjellefonna rockslide rather than an earthquake

giant rockslides from the inside the growing body of research on large scale mass wasting events so far has only scarcely investigated the sedimentology of chaotic deposits from non volcanic terrestrial landslides such that any overarching and systematic terminological framework remains elusive yet recent work has emphasized the need for better understanding the internal structure and composition of rockslide deposits as a means to characterise the mechanics during the final stages of runout and emplacement we offer a comprehensive overview on the occurrence of rock fragmentation and frictional melt both at different geographic locations and different sections within large 10 6 m 3 rockslide masses we argue that exposures of pervasively fragmented and interlocked jigsaw cracked rock masses basal melange containing rip up clasts and phantom blocks micro breccia and thin bands of basal frictionite are indispensable clues for identifying deposits from giant rockslides that may remain morphologically inconspicuous otherwise these sedimentary assemblages are diagnostic tools for distinguishing large rockslide debris from macro and microscopically similar glacial deposits tectonic fault zone breccias and impact breccias and thus help avoid palaeoclimatic and tectonic misinterpretations let alone misestimates of the hazard from giant rockslides moreover experimental results from mossbauer spectroscopy of frictionite samples support visual interpretations of thin sections and demonstrate that short lived 1500 degrees c in the absence of water occurred at the base of several giant moving rockslides this finding supports previous theories of dry excess runout accompanied by comminution of rock masses down to gm scale and indicates that catastrophic motion of large fragmenting rock masses does not require water as a potential lubricant

on the dynamics of the kofels sturzstrom geomorphologic data from the kofels landslide in the otz valley are compared with the results of computer modelling the study discusses the dynamic information that can be extracted from the data and argues that a standard coulomb friction model cannot adequately explain the observed features

multi stage structural and kinematic analysis of a retrogressive rock slope instability complex preonzo switzerland abstract large catastrophic rock slope failures are difficult to predict because the underlying mechanisms causing slope accelerations are difficult to study under in situ conditions for slope failures with compound basal rupture planes not only fracture propagation and slip in the basal rupture surface but also within the landslide body control the displacement evolution and time to failure the preonzo instability complex in southern switzerland failed several times since 2002 and offers a unique opportunity to study these mechanisms under in situ conditions the largest failure at preonzo occurred in may 2012 and was conditioned by large slope parallel nne ssw fracture zones which are intersected by ne and sw and e w striking faults creating diverging lateral boundaries whereas in the head scarp region oblique and flexural toppling along pre existing fracture sets is the prevailing mechanism sliding of either planar or wedge type is the preferred kinematic mode facilitated by the new discontinuities developed within the basal rupture surfaces these dominating mechanisms leading to a classical rock slope collapse could only be revealed in retrospect we compare fracture patterns in stable ground tectonic and unloading fractures with new fractures related to rock slope failure observed on basal rupture surfaces and in the head scarp simplified mechanical and kinematic analyses show that old pre existing tectonic fractures cannot accommodate substantial deformations under the in situ stress conditions and propagate connect through curved wing cracks forming at high angles this situation favors the development of new nearly slope parallel fractures which are interpreted as synthetic p shears along localized shear zones fractographic markings on these fractures indicate a continuous and relatively fast formation which presumably has taken place during a period of about 60 years prior to catastrophic failure this detailed description of the multi stage evolution of slope failure at preonzo represents a unique data set for future numerical studies of progressive failure in crystalline rocks

rock avalanches clusters along the northern chile coastal scarp abstract rock avalanche clusters can be relevant indicators of the evolution of specific regions they can be used to define the type and intensity of triggering events their recurrence and potential probability of occurrence the progressive damage of the rock mass the mechanisms of transport and deposition as well as the environmental conditions at the time of occurrence this paper tackles these subjects by analyzing two main clusters of rock avalanches each event between 0 6 and 30 mm 3 separated by few kilometers and located along the coastal scarp of northern chile south of iquique it lies hence within a seismic area characterized by a long seismic gap that ended on april 1st 2014 with a m w 8 2 earthquake the scar position high along the coastal cliff supports seismic triggering for these clusters the deposits relative positions are used to obtain the sequence of rock avalanching events for each cluster the progressive decrease of volume in the sequence of rock avalanches forming each cluster fits well the theoretical models for successive slope failures these sequences seem to agree with those derived by dating the deposits with ages spanning between 4 kyr and 60 kyr an average uplift rate of 0 2 mm yr in the last 40 kyr is estimated for the coastal plain giving a further constraint to the rock avalanche deposition considering the absence of reworking of the deposits volume estimates and datings allow the estimation of an erosion rate contribution of about 0 098 0 112 mm km 2 yr 1 which is well comparable to values presented in the literature for earthquake induced landslides we have carried out numerical modeling in order to analyze the mobility of the rock avalanches and examine the environmental conditions that controlled the runout in doing so we have considered the sequence of individual rock avalanches within the specific clusters thus including in the models the confining effect caused by the presence of previous deposits bingham rheology was the most successful at explaining both the distance and the geometry of the observed events