paraglacial rock slope stability glaciation and deglaciation along with their associated climatic and non climatic processes modify slope stresses and influence slope stability paraglacial slope failures are those that are a part of or influenced by the transition from glacial conditions to non glacial conditions gravitational failure of rock slopes is a primary and dominant process of slope evolution in mountainous terrain and is the subject of this paper which 1 reviews the approaches taken for researching paraglacial rock slope failure patterns and processes 2 summarises the spatial and temporal patterns of post glacial failures 3 assesses the factors influencing slope stability during glaciation and deglaciation 4 explores some of the applications of paraglacial research and 5 highlights some of the outstanding issues to be resolved and provides recommendations for terminology relating to paraglacial slope processes

monsoon fluctuations in two 20 000 yr b p oxygen isotope pollen records off southwest india abstract two marine pollen diagrams for sediments off the southwest coast of india provide a 20 000 yr history of the nearby continental vegetation determined by the monsoon climate within the framework of the isotopic stratigraphy two important phases of the evolution of the monsoon climate are a very arid period about 22 000 18 000 yr b p and a very humid period culminating at 11 000 yr b p the very arid period corresponds to the lowest pollen representation of mangrove vegetation which is used here as an indirect indicator of monsoonal runoff this aridity is due to a very weak southwest airflow a great reduction of summer monsoonal rainfall and reduced runoff of the western ghats rivers the extension of the monsoon over india after the last glacial maximum has been a gradual process following the northward progression of the intertropical convergene zone the very humid period corresponding to the highest pollen representation of mangrove vegetation and the heaviest summer rainfall is a climatic response to the maximum summer insolation of the northern hemisphere at 11 000 yr b p

the earthquake triggered rock avalanche of cui hua qin ling mountains p r of china the benefits of a lake damming prehistoric natural disaster abstract this paper deals with an investigation of cui hua rock avalanche in the qin ling mountains in the dong cha valley an eastern branch of taiyi river some 30 km south of xi an province of shaanxi p r of china the landslide originated on lithotectonic structures along seismic active fault systems its occurrence could be correlated with an earthquake in 780 bc that must have triggered the landslide due to a stabilizing human input the landslide area in front of the dammed tianchi lake became an area of settlement for native people of this area which used this rapidly geomorphologic changing system for their needs over the past 2780 years nowadays the lake is considered to be a reservoir for drinking water agriculture and a hydropower plant even more the deposit of the cui hua rock avalanche has become a touristic place for sightseeing and vacation

methane rich plumes on the carolina continental rise associations with gas hydrates seafloor venting of microbial gases occurs at 2167 m water depth over the blake ridge diapir gas rich plumes were identified acoustically in the water column up to 320 m above a pockmarked sea floor associated with active chemosynthetic biological communities plumes and venting fluids emanate from near a small fault that extends downward toward a dome in the bottom simulating reflector indicating that fluid and or gas migration is associated with gas hydrate bearing sediment below these plumes might be caused by gas bubbles or buoyant dumps of gas hydrate that float upward from the seafloor 18 refs 3 figs

a slab on slab model for the flims rockslide swiss alps the flims rockslide is the largest landslide in the alps with an estimated volume of 12 km3 it resulted from a prehistoric high speed movement of a large limestone mass several main factors infl

the pandemonium creek rock avalanche british columbia in 1959 a rock spur became detached from the headwall of a cirque near pandemonium creek in the southern coast mountains of british columbia approximately 5 000 000 cu m of blocky gneissic quartz diorite debris travelled 9 0 km along a highly irregular path descending a vertical distance of 2 km to the valley of south atnarko river the high mobility of the rock avalanche is manifested by superelevation in valley bends two run ups and two right angle changes in flow direction this mobility is due in part to 1 peculiarities in the path of the landslide lateral moraines for example funnelled and accelerated the debris and 2 travel over a glacier below the detachment zone although most of the debris came to rest on the upper part of a fan at the mouth of pandemonium creek one lobe traversed the fan and entered knot lakes where it generated displacement waves that destroyed trees along the shore run up and superelevation data indicate that the debris was moving between 81 and 100 m s as it entered the run up zone at pandemonium creek and 21 38 m s in pandemonium valley to the east these velocities were analysed by applying the dynamic model of h j korner rock mechanics 1976 8 225 256 to the path of the landslide the analysis suggests that the rock avalanche had two phases a very rapid initial phase from detachment to the beginning of the run up and following sudden energy losses at the run up a second phase involving much lower velocities the pandemonium creek landslide is similar in many respects to much larger highly mobile rock avalanches in other parts of the world for example huascaran peru and little tahoma peak washington u s a although much less common than rockfalls and debris flows rock avalanches are capable of far greater damage this is a consequence of their size and the fact that they travel great distances at high velocities the potential exists for other highly mobile landslides of the pandeminium creek type in the mountains of western canada highlighting the need for caution in the future development of this region

petroleum related hydrocarbon seep age in a recent north sea sediment abstract in the summer of 1985 unocal carried out a 55 day surface geochemical survey in the norwegian sector of the north sea the program was set up to include a variety of geochemical techniques to aid evaluation of their effectiveness for detecting hydrocarbon seepages in the marine environment the ship was equipped with both bottom water and bottom sediment sampling devices and an analytical laboratory and computer network so that onboard measurements and real time data interpretation could be made during the survey 4100 line kilometers of bottom water data 11 000 sites and 320 sediment cores were obtained a major hydrocarbon gas anomaly was defined during part of the bottom water sampling program a set of sediment cores was taken in the vicinity of this anomaly the data from these cores are used to illustrate the fate of hydrocarbon migration through unconsolidated marine sediment migration by bubble ebullition transports hydrocarbons through the near surface sediment and produces gas plumes in the bottom water trapping of bubbles in the sediment will produce patchy temporal hydrocarbon anomalies in the sediment however extensive sediment anomalies such as those proposed to be developed by microseepage can only be formed at depth in the sediment below the level where sulfate is depleted from the pore water these anomalies result because vertical migration by molecular diffusion creates a steady state hydrocarbon oxidation zone sulfate reduction zone at depth in the sediment which efficiently eliminates hydrocarbon transport further to the surface

the zymoetz river rock avalanche june 2002 british columbia canada abstract on june 8 2002 the pacific northern gas pipeline in the zymoetz river valley was severed by a large debris flow the event initiated as a rock avalanche in glen falls creek a tributary of the zymoetz river the rock avalanche involved 1 106 m3 of volcaniclastic bedrock and travelled through a complex flow path to finally deposit a large fan in the main zymoetz river approximately half of the debris volume was deposited in the cirque basin at the head of the valley with the rest deposited in the channel and the fan examination of the initiation zone showed a very persistent slightly curved joint set that forms the main sliding surface for the failed block with a dip of 45 and dip direction of 300 a geographic information system gis was used to examine the event and allowed for further interpretation of field data preliminary dynamic analysis indicates that the event reached velocities of up to 34 m s comparison of the zymoetz river rock avalanche zrra with other similar events from the literature indicates that it exhibited similar mobility and velocities as evidenced from the literature these long runout events can cause significant damage and have the potential to be a very high risk as forestry and recreation activities spread further into remote areas

crevice type caves as initial forms of rock landslide development in the flysch carpathians crevice type caves formed along joints are very common in the polish flysch carpathians more than 600 have been recorded the caves represent accessible parts of the widened cracks which are basic initial forms of development of deep seated rock landslides structural features of four selected caves situated in different parts of the carpathians were studied in order to determine relations between joint systems and landslide formation the studies prove that the main rock scarps often represent effects of earlier propagation of the cracks cutting surfaces due to loading and unloading shearing stress the cracks are structural forms developed along joints or faults the cutting surfaces represented by cracks caves develop a long time before the main gravitational mass movements whereas the sliding surfaces shearing zones are formed or significantly modified ad hoc during the gravitational transport of rock masses occurrence of the deep initial cracks causes modification of shape of the sliding surfaces which are noncircular the mountain slopes cut by many cracks are permanently developed thus the periodic increase of activity of external factors floods downpours earthquakes etc leads to common formation of the landslides earlier prepared by crack development this model of slope evolution enables us to interpret the occurrence of the landslide phases in the holocene during which increasing of frequency of the landslides is observed

the rock avalanche of february 1995 at claix french alps abstract the sedimentology of a rock avalanche involving ca 7 10 3 m 3 that happened on february 1995 at claix the french alps is analysed here the talus shows a proximal depression due to the impact of the debris then a grooved area with few mainly sandy silt deposits and a downslope accumulation of coarse debris that reaches up to 3 m in thickness the material underwent mass movement as demonstrated by the steep distal front the strong fabric strength and the thrust planes the greatest part of the deposits consists of a clast supported to partially openwork debris with angular clasts over a sheared matrix supported basal layer the largest blocks often more than 1 m in length are concentrated at the surface and the front the overall sedimentological characteristics are similar to those of the small dry grain flows that occur usually on rockfall talus except for the abundance of fine grained particles that results from intense cataclasis during flow it is suggested that the deposits of such medium scale rock avalanches probably not uncommon in seismic regions may have been confused in previous studies with other slope mechanisms such as debris flow and rockfall

large landslides and deep seated gravitational slope deformations in the czech flysch carpathians new lidar based inventory abstract moderate relief landscapes such as the czech flysch outer western carpathians cowc in comparison with alpine regions are rarely subject to extensive landslide inventory mapping an understanding of landslides in such a landscape is needed because densely populated hilly landscapes in temperate zones are usually of major socio economic importance in this study we performed the first lidar based landslide mapping for the entire cowc area 7539 km2 one of the most landslide prone regions in europe by calculating various landscape and landslide metrics we infer the distribution frequency area relationships kinematics and controls of mass movements with special attention on large landslides 0 1 km2 and deep seated gravitational slope deformations dsgsds we mapped a total of 13 611 landslides of which 1357 failures are large landslides and dsgsds whereas the lower and more subdued areas in the southern part of cowc are hotspots in terms of the total number of landslides the higher and more topographically pronounced areas in the northeast are affected predominantly by large landslides and dsgsds however landslides with 0 1 km2 are widespread throughout the whole territory of cowc a discrepancy also exists in the spatial distribution of different types of landslides rock slides and dsgsds are dominant in the north east while flow type landslides are dominant in the southern lower topographic relief with claystone dominated flysch we conclude that 1 distinct geological units nappes produce landslide populations with different frequency area distributions 2 stratigraphic composition alongside the tectonic style of flysch formations control the type of landslides 3 dsgsds affect mainly slopes formed by rigid rocks sitting atop soft formations and 4 geological conditions rather than topography control distribution of large landslides and dsgsds in cowc

deep seated gravitational slope deformations in the highest parts of the czech flysch carpathians evolutionary model based on kinematic analysis electrical imaging and trenching deep seated gravitational slope deformations dsgsds played an important role during the quaternary evolution of mountain ridges formed by anisotropic flysch rocks of the outer western carpathians owc four dsgsd affected ridges in the highest part of the czech sector of the owc have been subjected to multidisciplinary investigation involving mapping structural and kinematic analysis geoelectrical imaging trenching and dating all the studied dsgsds are strongly predisposed by regional structural fabric given by the intersection of bedding planes joint sets and faults performed research suggests high diversity of mechanisms leading to the origin of individual dsgsds the area of a single dsgsd can be affected by various types of movements such as sackung lateral spreading toppling or incipient sliding electrical imaging and trenching revealed that besides these mechanisms anisotropic flysch massifs formed by thick bedded sandstones are strongly exposed to subsurface opening of air filled voids related to widened crevices such a process is driven by deep seated creep and translational sliding of sandstone beds upon plastic claystones whose strength has been reduced to residual values of the angle of internal friction performed radiocarbon and osl dating revealed that some of the studied dsgsds originated in the holocene period particularly in the atlantic and subboreal chronozones

influence of tectonic structures on the hope slide british columbia canada abstract the hope slide which occurred on january 9 1965 involved an estimated 47 mm3 of meta volcanics and intrusive rocks previous workers reported the presence of tectonic structures faults and shear zones along the failure surface at the hope slide these tectonic features were investigated in detail to assess their effects on rock mass quality and the related implications for slope stability this paper integrates basic field and laboratory concepts from structural and engineering geology subdividing the failure area into structural domains allowed distinct discontinuity sets to be associated with specific tectonic structures the geological strength index gsi was used to estimate the rock mass damage related to the tectonic structures low gsi values were seen to outline tectonic damage zones point load tests were used to characterise the compressive strength of rocks adjacent to the tectonic structures strength anisotropy tentatively attributed to damage caused by a large shear zone was observed in greenstone samples seepage zones along the failure surface were observed preferentially along shallow discontinuities that dipped downslope and in rock masses of good quality gsi 40 an alternative morphology of the slope failure is proposed by distinguishing between the extent of the surficial damage due to the rock slope failure and the zone of failed material depletion zone for the first time a kinematic mechanism for the hope slide is proposed based on a preliminary 3 dimensional block model a pre 1965 dem was produced from estimates of material lost and gained as reported by previous workers the pre 1965 dem revealed that the tectonic structures recognised during fieldwork bounded the material that failed in the 1965 event

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

potential impact on climate of the exploitation of methane hydrate deposits offshore abstract considerable attention has focussed on methane hydrates as a potential energy resource but much less on the potential environmental problems of exploiting these deposits in fact methane hydrate deposits represent a dynamic system formed as a result of the continuous migration of methane gas along fracture systems any exploitation of methane hydrates offshore will perforce take place in these unstable systems and could lead to the large scale release of ch 4 under unfavourable circumstances however most of this ch 4 would be oxidized to co 2 within the water column under steady state conditions only under exceptional circumstances would large scale release of ch 4 into the atmosphere take place the impact of exploiting these deposits offshore on global climate may therefore be limited provided serious efforts are made to minimize environmental impacts at present prospects for the commercial exploitation of methane hydrates are in their infancy considerable ingenuity will be required to satisfy the requirements of safe operating conditions mitigation of environmental hazards and commercial viability the need to exercise caution before attempting to exploit these deposits is emphasized

some northern sources of atmospheric methane production history and future implications northern sources including wetlands and perhaps gas hydrates contribute significantly to the ch4 content of the atmosphere methane production from northern wetlands including bogs swamps and ponds is probably very seasonal being most important in late summer with significant evasion in autumn as lakes overturn the strong recovery of beaver populations in canada from near extinction 50 years ago to present abundance may also be important both in creating new wetlands and in the alteration of them wetlands that have been altered by beaver activity produce orders of magnitude more methane than beaver free wetlands in the arctic methane gas hydrates represent a significant source of methane which may become more important if arctic warming occurs as part of global climate change the danger of a thermal runway caused by ch4 release from permafrost is minor but real other high latitude sources of ch4 include arctic peat bogs and losses from natural gas production especially in the soviet u

ground penetrating radar refraction imaging with stacked refraction convolution section method abstractwe have evaluated a technique initially developed for the seismic refraction imaging the stacked refraction convolution section srcs which we have properly adapted to process ground penetrating radar gpr refraction data through a mute operation the subsurface refracting signals recorded by the receiver from two reciprocal sources are selected following that a velocity analysis by means of the crosscorrelation of the refracted signals and the convolution of resulting traces is performed the refraction image in intercept times is successively derived from three main steps namely 1 the convolution of the subsurface refracted signals 2 the crosscorrelation of convolved trace with the reciprocal refracted signal and 3 the stacking of crosscorrelated traces over all source couples the technique is not only suitable for the processing of gpr data acquired with two or more reciprocal common source profiles but it is also convenient for its low acquisition cost in addition to the si

sedimentary framework of penobscot bay maine abstract analyses of seismic reflection profiles along with previously collected sediment samples and geologic information from surrounding coastal areas outline the characteristics distribution and history of the strata that accumulated within penobscot bay maine during the complex period of glaciation crustal movement and sea level change since late wisconsinan time sediments that overlie the rugged glacially eroded surface of paleozoic bedrock range in thickness from near zero to more than 50 m and consist of four distinct units 1 1 massive to partly stratified coarse grained drift forms thin 2 2 well stratified fine grained glaciomarine deposits are concentrated in bedrock depressions beneath the main passages of the bay during the period of ice retreat and marine submergence these sediments settled to the sea floor draped the irregular underlying surface of bedrock or drift and accumulated without disturbance by physical or biologic processes 3 3 heterogeneous fluvial deposits fill ancestral channels of the penobscot river beneath the head of the bay the channels were incised during a 40 m postglacial low stand of sea level due to crustal rebound and later were filled as base level was increased during holocene time 4 4 muddy marine sediments which are homogeneous to weakly stratified and rich in organic matter blanket older deposits within bathymetric depressions in the middle and lower reaches of the bay and cover a pronounced gently dipping erosional unconformity in the upper reach these sediments were deposited during the holocene transgression as sea level approached its present position and the bay became deeper late wisconsinan and holocene sedimentation in penobscot bay has smoothed the sea floor but it has not completely obscured the ice sculptured bedrock topography

large scale brittle and ductile toppling of rock slopes slow ductile toppling of rock masses commonly creates large scale mountain slope deformations in some cases rock toppling can initiate an extremely rapid catastrophic landslide this theoretical and field based study was aimed at distinguishing the two alternative modes of toppling the idea that certain key parameters of the undeformed rock mass may influence failure behaviour in a quantifiable way was examined through a parametric study of a large rock slope using the universal distinct element code udec the slope was modelled using variations of rock mass strength discontinuity orientation and persistence and toe over steepening the results indicated two distinct types of failure behaviour i ductile self stabilizing flexural toppling in weak rock with a single dominant joint set and ii brittle catastrophic block toppling in strong rock containing persistent down slope oriented or horizontal cross joints which act as surfaces of separation at the base of the toppling blocks the two m

evolution stages of large deep seated landslides at the front of a subalpine meridional chain maritime alps france abstract studying long term evolution of gravitational slope evolution is a key to understanding deep seated landslide processes this paper deals with three large deep seated landslides dsls at a front of a subalpine meridional chain on the la marbriere slope near the town of grasse alpes maritimes france the geological framework controlling the stability and morphology of the dsls is associated with thick and tamped triassic layers of mudstone with gypsum overlain by highly faulted jurassic limestone gravitational deformation affects the entire slope involving a movement of about 1 1 10 8 m 3 of rock material it creates large disturbances in landscape morphology such as scarps counter slope scarps trenches and other typical gravitational morpho structures geomorphological mapping coupled with deep electrical resistivity tomography ert reveals a strong correlation between these morpho structures and inherited brittle tectonic features this observation relies on spatial and geometrical relations on the surface and at the depth of more than 150 m checked by ert between the most persistent fault and the gravitational morpho structures the specific distribution of the morpho structures on the basis of their morphological typologies and variations in the stage of evolution of three dsls provides an interpretation of their kinematics during the last 400 ka it appears that soft substratums combined with inherited persistent anisotropies are key factors in the development of the dsls indeed outflow of mudstone due to the lithostatic pressure imposed by individual limestone compartments has led to general slope subsidence then a progressive toppling of a rock mass may have led to the catastrophic rock collapse along bedding planes the evolution of the dsls can be divided into three distinct stages represented by three zones a young collapse stage zone 1 a pre collapse stage zone 2 and an old mature stage 400 ka zone 3 as the dsls occur on the same slope and in the same geological context this area offers interesting perspectives for understanding factors controlling the long term gravitational evolution of slopes

the largest prehistoric landslide in northwestern slovakia chronological constraints of the kykula long runout landslide and related dammed lakes abstract this study deals with the chronology of the largest long runout landslide in the northwesterrn part of the western flysch carpathians kysucke beskydy mts slovakia despite the impossibility of using direct radiocarbon dating method time constraints for the evolution of the landslide were determined on the basis of the dating of various sedimentological geomorphological elements situated on and adjacent to the landslide body the results show that the landslide evolved between 10 3 and 9 0 ka 14 c bp i e in the wider transitional phase between the late glacial lg and the holocene the main mass movement activity took place at the turn of the younger dryas preboreal chronozones whereas retrogressive activity continued up to the preboreal boreal transition radiocarbon dating together with pollen analysis and sedimentology of landslide dammed palaeolakes and colluvial peat bogs revealed almost continuous holocene palaeogeographical records between 10 3 and 3 3 ka 14 c bp periods of enhanced sediment supply to the reservoirs in 9 9 9 0 8 4 8 2 6 9 6 5 and 4 5 ka 14 c bp correlate well with palaeogeomorphic and palaeohydrological records from nearby polish carpathians the study confirms that the lg holocene transition represented a favourable period for the evolution of large landslides not only in glaciated high mountain areas but also in medium high mountains of central europe

mid holocene cluster of large scale landslides revealed in the southwestern alps by 36cl dating insight on an alpine scale landslide activity abstract although it is generally assumed that the internal structure of a slope e g lithology and rock mass properties inherited faults and heterogeneities etc is preponderant for the progressive development of large scale landslides the ability to identify triggering factors responsible for final slope failures such as glacial debuttressing seismic activities or climatic changes especially when considering landslide cluster at an orogen scale is still debated highlighting in this study the spatial and temporal concordant clustering of deep seated slope failures in the external southwestern alps we discuss and review the possible causes for such wide spread slope instabilities at both local and larger alpine scale high resolution field mapping coupled with electrical resistivity tomography first allows establishing an inventory of large landslides in the southwestern alps determining their structural model precising their depth limit 100 200 m as well as the involved rock volumes 10 7 m 3 we show that they developed in the same geostructural context of thick mudstone layers overlain by faulted limestone and followed a block spread model of deformation that could evolve in rock collapse events cosmic ray exposure dating cre using both 36 cl and 10 be in coexisting limestone and chert respectively has been carried out from the main scarps of six deep seated landslides dsl and leads to landslide failure cre ages ranging from 3 7 to 4 7 ka they highlighted i mainly single and fast ruptures and ii a possible concomitant initiation with a main peak of activity between 3 3 and 5 1 ka centered at ca 4 2 ka because this region was not affected by historical glaciations events landslide triggering by glacial unloading can be excluded the presented data combined with field observations preferentially suggest that these failures were climatically driven and were most likely controlled by high pressure changes in the karstic medium in effect the chronicle of failure ages is concomitant to a well known climatic pulse the 4 2 ka climate event characterized by intense hydrological perturbations associated to the heaviest rainfall period of the entire holocene despite requiring further investigations and discussions the dating of numerous events across the entire alps during the middle holocene period suggests a potential synchronous triggering of several large scale gravitational failures induced by the mid holocene climatic transition

gigantic seismogenic landslides of summer lake basin south central oregon subsidence of summer lake basin situated in the northwestern basin and range province in south central oregon has exposed a kilometer thick neogene sequence of dense volcanic flow rocks overlying very weak tuffaceous sedimentary rocks in the bounding winter ridge slide mountain escarpment subsidence occurs along the active 40 km long winter ridge slide mountain fault which is capable of producing mw 7 earthquakes with near field maximum horizontal acceleration approaching 1 g gigantic landslides cubic kilometers in volume scallop the southwestern part of the escarpment and the deposits run out several kilometers characteristic of rock avalanches geotechnical rock mass characterization and slope stability analyses confirm observations that these landslides were initiated within the weak tuffaceous sedimentary rocks along shallow east dipping planar failure surfaces are insensitive to groundwater fluctuations and are stable under static conditions pseudostatic analyses reveal that strong shaking is required to trigger landsliding the bennett flat landslide failed as a single event between 900 270 ka and 16 8 ka the landslide has a depletion zone volume of 1 1 km3 but only 0 3 km3 of debris is discernible in the accumulation zone the foster creek landslide also appears to have failed as a single event between 180 and 16 8 ka the landslide has a depletion zone volume of 2 9 km3 but only 0 3 km3 of debris is discernible in the accumulation zone the punchbowl landslide evidences multiple events the most recent of which failed in the holocene and had a volume of 0 4 km3 0 5 km3 of debris is found in the accumulation zone

velocity and runout simulation of destructive debris flows and debris avalanches in pyroclastic deposits campania region italy the campanian apennines are characterized by the presence of monocline ridges mainly formed by limestone during the periods of volcanic activity of the somma vesuvius and phlegrean fields the ridges were mantled with pyroclastic materials in varying thickness the pyroclastics have been involved in destructive landslides both in historical time and in the recent past 1997 1998 1999 the landslides occur following intense and prolonged rainfalls in some cases landslides extended up to 4 km into the surrounding lowlands and reached towns causing severe destruction and over 200 deaths generally the landslides begin as small debris slides that develop into large shallow debris avalanches or debris flows involving pyroclastic horizons and colluvial soils 0 5 2 m thick on steep and vegetated slopes often at the heads of gullies during motion the landslide materials eroded vegetation and soils from the slope so that the moving material volume tended to increase then proceeding towards and beyond the base of the slopes the phenomena evolved into hyperconcentrated streamflow due to dilution by incorporating water the results of motion analyses are described an empirical rheological relationship was used including two principal terms that depend on the total normal stress and on the flow velocity on this basis the model has simulated the velocity and duration of debris avalanches and the distribution of the deposits the selected areas were those of sarno quindici and cervinara where a large amount of data is available both on the material properties and geomorphological setting it was found that the majority of the cases at the two sites can be simulated successfully with only one specific pair of rheologic parameters this provides the possibility for first order predictions to be made of the motion of future landslides such predictions will be a valuable tool for outlining potential hazard areas and designing remedial measures

landslide induced river channel avulsions in mountain catchments of southwest new zealand pulsed or chronic supply of landslide debris to valley floors has historically caused substantial aggradation and channel instability in several alpine catchments of sw new zealand in this regional investigation of landslide impacts on river morphology three types of landslide induced channel avulsion are discerned i upstream backwater avulsions ii contact avulsions and iii downstream loading avulsions the basis for this qualitative geomorphic process response framework is the principal direction of fluvial response with respect to its position relative to the causative landslide emplacement site downstream avulsions have the highest damage potential to land use and infrastructure on unconfined mountain fringe alluvial fans in the wake of such events catastrophic aggradation may obliterate up to several km2 of mature floodplain forests by burial under several metres within a few decades estimates of mean aggradation rates are high 220 mm year 1 and exceed long term 103 year trends of fluvial degradation by an order of magnitude future potential avulsion routeways may be detected by geomorphic mapping of abandoned channels which are preferentially reactivated in the wake of landslide induced sediment waves

late holocene catastrophic slope collapse affected by deep seated gravitational deformation in flysch ropice mountain czech republic the region of the flysch western carpathians is characterized by abundant deep seated gravitational slope deformations dsgsds this study deals with a detailed analysis of late holocene catastrophic collapse of a fault created slope of mountain ropice in the moravskoslezske beskydy mountains eastern czech republic the catastrophic collapse was initialized by huge compound rotational slide toppling deformation which occurs on the upper part of the studied slope and affects tectonically weakened subhorizontally inclined sandstone beds detailed geomorphological mapping accompanied by morphotectonic analysis and geophysical sounding revealed at least two historic flowslides the older event f1 affected 0 5 0 8 mm3 of bedrock and created a 1000 m long and up to 150 m wide accumulation with abundant transverse steps and a carapace like surface the landslide toe blocked an adjacent valley which led to the development of a small impoundment with 4 m thick deposits containing lacustrine peat bog floodplain and alluvial fan facies radiocarbon dating and pollen analysis indicate the valley blockage at 1 5 ka bp the other flowslide f2 of much smaller dimensions 10 000 12 000 m3 overlaid the main landslide body and according to the dating of minerogenic horizon in the impoundment may have taken place 0 3 ka bp the organisation of landforms character of slope failures and dynamic back modelling point to a likely rock avalanche or combined rock slide debris avalanche mechanism of movement this case study shows that rapid rock avalanches can operate also in mountainous terrain with moderate relief if toppling together with deep seated gravitational deformation of slopes modifies the original stable position of bedding planes

a large landslide on the urban fringe of metropolitan phoenix arizona a granitic rock avalanche one of the largest quaternary landslides in arizona outside the grand canyon with a volume of approximately 5 25 m m 3 and a width a little under 0 5 km ran 1 km from the eastern mcdowell mountains with lateral levees and pressure ridges the rock avalanche deposit displays many features found on classic sturzstroms failure occurred along a major joint plane paralleling the slope with a dip of 448 when a major base level lowering event in the salt river system would have undermined the base of the failed slope and probably during a period of more moisture than normally available in the present day arid climate failure at the subsurface weathering front highlights the importance of the dramatic permeability change between grussified regolith and relatively fresh bedrock rock varnish microlaminations vmls dating in concert with other geomorphic evidence suggests that the rock avalanche deposit is slightly older than 500 ka the rock vanish results also have important implications for sampling strategies designed to use cosmogenic nuclide to date quaternary landslide deposits discovery of a large landslide in close proximity to the extending urban fringe of metropolitan phoenix argues for a more careful analysis of landslide hazards in the region especially where rapid development excavates bedrock at the base of steep mountain slopes and where the subsurface weathering front is near the surface d 2004 elsevier b v all rights reserved

time constraints for the evolution of a large slope collapse in karstified mountainous terrain of the southwestern crimean mountains ukraine abstract deep seated gravitational deformations are significant denudational agents of rock slopes at the margins of karstified plateaus of the crimean mountains ukraine the aim of this article is to study long term evolution of a giant rock slope failure close to the black sea coast in the southwestern tip of the mountains near foros town the failure evolved in highly anisotropic limestones overlying plastic flysch layers where the main headscarp follows a strike slip fault we tested a new chronological strategy based on 14 c and u th series dating of speleothems from unroofed caves exposed in the headscarp area of the slope failure this approach made it possible to state maximum age of the slope collapse in individual parts of the deformed slope obtained results indicate that extension of discontinuities together with their karstification can be traced to 300 ka bp whereas evolution of the main headscarp started 110 ka bp and since then it has propagated in the eastward direction the youngest slope failure in the easternmost part of the studied collapse is of late holocene age our study indicates that conditions for large rock slope failures in carbonate areas can be prepared by speleogenesis or combined effects of propagation of cracks and their solution based expansion furthermore large rock slope failures can be important factors for the genesis of unroofed caves

evaluation of meteorological controls of reconstructed rockfall activity in the czech flysch carpathians the spatio temporal characteristics of rockfall activity were studied at four localities representative of old landslides in the highest part of the czech flysch carpathians moravskoslezske beskydy mountains historical activity chronology and spatial context of rockfall activity were reconstructed using dendrogeomorphic techniques and rockfall rate index rr a total of 1132 increment cores from 283 trees growing in the rockfall transport and accumulation zones enabled the dating of 989 rockfall events reconstruction of a 78 year long rr chronology suggests similar rockfall histories and trends at all study sites indicating the existence of major common factors driving rockfall dynamics in the region temporal analysis and correlation of the rr series obtained with monthly mean temperatures numbers of days with temperature transitions through 0 deg c and monthly precipitation totals show that meteorological characteristics have evident but variable influence on rockfall activity

observations of the latitude dependence of the location of the martian magnetic pileup boundary 1 we report observations that show the dependence of the altitude of the magnetic pileup boundary mpb at mars on planetary latitude as seen by the mars global surveyor magnetometer electron reflectometer instrument the mpb is further away from mars on average at southern latitudes than at northern latitudes the data are consistent with a mpb distance mapped to the terminator plane that does not vary with latitude in the northern hemisphere but increases with increasing southern latitude in the southern hemisphere we also report increased variability in the mpb distance within the longitude range 90 270 e longitude in the southern hemisphere which is the region that contains the strongest crustal magnetic fields these trends are most obvious in a planet fixed coordinate system indicating a planet fixed driver of the mpb location the proposed mechanism is the local diversion of shocked solar wind flow by crustal magnetic fields

quaternary catastrophic rock avalanches in the central apennines italy relationships with inherited tectonic features gravity driven deformations and the geodynamic frame abstract five cases of quaternary rock avalanches detached from carbonate mountain ridges in the central apennines are presented due to the large amount of rock masses involved the width of accumulation and detachment areas and the damming in the host environment the analysed rock avalanches can be considered as catastrophic rock slope failures sporadic events in a mountain region characterized by low elevation but where mountain ridges can have a relative elevation of up to 1 km above the lowermost valley floors the geological setting of tectonic structures that originated during the apennine orogenesis influenced rock avalanche characteristics determining the location and shape of detachment areas the kind of rock mass involved and the failure mechanisms two main types have been identified i forelimb rock slide avalanches frsa such as the lettopalena and mt arezzo rock avalanche which involved cenozoic heterogeneous sequences of carbonate ramp deposits detached from box shaped source areas according to a rock sliding mechanism and ii backlimb slide wedge rock avalanches bswra such as the campo di giove scanno and celano rock avalanches that detached from sub circular source areas carved on fault bounded ridges and involving meso cenozoic carbonate rocks with a combined sliding and rock wedge failure mechanism the campo di giove lettopalena and scanno rock avalanches originated from mountain ridges bounded by inactive fault zones and undergoing deep seated gravitational slope deformations dsgsds at the mountain scale these three rock slope failures are considered as isolated events of long lasting deformative processes featuring creep deformation gravity driven deformations firstly generated as a response to stacking processes and synchronous normal faulting during the neogene early pleistocene apennine tectonics in particular the caramanico fault system cfs and the genzana fault gf bordering the carbonate ridges from which the campo di giove and scanno rock avalanches originated respectively are here considered as backlimb collapse structures accommodating the passive uplift and deformation of positive tectonic structures gravity driven deformations persisted during the post early pleistocene dome like uplift of the whole apennine region the regional uplift created the first order 200 km topographic wave length of the belt i e a periodic loading which has been balanced by the deflection of the apennine crust and lithosphere on the contrary shorter topographic wave lengths inherited from former thrusting and synchronous normal faulting determined local isostatic imbalances bearing a large potential for the mature development of dsgsds on mountain ridges favoured also by lateral unloading due to linear erosion and increase of topographic stress thus a cause effect relationship is hypothesized between the geodynamic evolution of the belt and mountain sized gravity driven deformations including large rock slope failures

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

gas charged sediments in the aegean and ionian seas greece abstract during the last fifteen years marine seismic surveys in the aegean and ionian seas have revealed numerous acoustic anomalies i e acoustic turbid zones gas pockets gas plumes enhanced reflectors columnar disturbances wipe outs and meso to micro morphological features such as pockmarks domes mud volcanoes and elongated depressions these are attributed to the presence of gas in sediment interstices the gas charged sediments are found in pleistocene and present day fjord like environments pleistocene and present day deltaic environments lakes and open sea environments the gas found in the quaternary fjord like and deltaic depositional environments is assumed to be of biogenic origin the gas found in the pre quaternary open sea environments is associated with faulting and salt doming and may therefore be of thermogenic origin although the sediment grain size is favourable for the formation of pockmarks the lack of them is probably due to the high seismicity which characterises these regions

acoustic masking in sediments due to gases on the western continental shelf of india abstract surveys carried out on the western continental shelf of india indicate that the inner and middle shelf to a depth of 50 60 m is covered by acoustically transparent clays on the shelf off bombay the clays are thin near the shore where they overlie rocks or sands and increase to 20 35 m on the middle shelf beyond which they thin out at a depth of 50 60 m where relict oolitic sands are exposed the shallow seismic and echosounding records of these clays at places are marked by turbidity which may be categorised as 1 extending over a distance of 50 60 km and covering large areas of over 2500 km 2 and 2 resembling isolated inverted u shaped features the turbidity appears to rise from the underlying reflectors to within 5 10 m of the sea bed these features are very prominent in two areas viz on the middle shelf off bombay and on the inner shelf the shallow bore holes drilled and the cores collected in the area show bubbles or fissures in the clays of the turbid zone the gas predominantly consists of methane with terraces of higher hydrocarbons the composition of the gas and the occurrence of the gassy sediments on the middle shelf and in the vicinity of the estuaries and rivers favours their biogenic nature the common depth of occurrence of 5 10 m may represent the boundary between the sulfate reducing zone and the underlying methane producing zone perhaps the gases were formed by the degradation of large quantities of organic matter produced by increased productivity or because of higher influx of organic matter in the recent past however the location of some of the occurrences in the vicinity of an oil and gas field indicate that the gases in the sediments of the outer shelf off bombay may be petrogenic and those on the middle and inner shelf off bombay konkan karnataka and kerala may be biogenic

quaternary tectonics and large scale gravitational deformations with evidence of rock slide displacements in the central apennines central italy eight cases of large scale gravitational movements with evidence of rock slide type displacements evolving close to quaternary faults have been analysed in the central apennines geomorphological and structural surveys have defined the relationship between the gravitational displacements and the tectonically controlled modifications of the landscape the evolution of all the investigated cases has been conditioned by the presence of fault planes located along the mountain slopes in most cases mt cefalone cima della fossa villavallelonga casali d aschi gioia dei marsi the faults played or are playing a primary role in increasing the local relief and their activity represents the main geomorphic factor conditioning the gravitational movements this kind of relationship has been observed along mountain slopes bordering depressions which have not been drained for most of their geomorphic history or have been characterised by an evolution of the hydrographic network that has been conditioned only by the local tectonic subsidence in such cases the gravitational movements develop in the footwalls of the faults in other cases fiamignano pescasseroli the faults have played a passive role since they only bound the sliding masses and coincide with the surficial expressions of the sliding planes therefore the gravitational displacements develop in the hangingwall of the faults the evolution is conditioned by the incision of the hydrographic network in response to regional quaternary uplift the illustrated case studies provide a wide range of examples of the gravitational response of slopes to the modifications of the landscape due to linear and areal tectonics the identification of the geomorphic traces of the large scale gravitational movements along fault controlled mountain fronts has implications for hazard particularly for the evolution of the displacement the quantitative analysis of the vertical displacements and data on the characteristics of the surface breaking during historical earthquakes demonstrate that along fault offsets strongly increases where the unstable large scale rock masses are located therefore the large coseismic vertical offset may represent a major problem for the displacement of utilities and may represent a potential cause for the sudden and catastrophic evolution of the gravitational movement

effects of large deep seated landslides on hillslope morphology western southern alps new zealand 1 morphometric analysis and air photo interpretation highlight geomorphic imprints of large landslides i e affecting 1 km2 on hillslopes in the western southern alps wsa new zealand large landslides attain kilometer scale runout affect 50 of total basin relief and in 70 are slope clearing and thus relief limiting landslide terrain shows lower mean local relief relief variability slope angles steepness and concavity than surrounding terrain measuring mean slope angle smoothes out local landslide morphology masking any relationship between large landslides and possible threshold hillslopes large failures also occurred on low gradient slopes indicating persistent low frequency high magnitude hillslope adjustment independent of fluvial bedrock incision at the basin and hillslope scale slope area plots partly constrain the effects of landslides on geomorphic process regimes landslide imprints gradually blend with relief characteristics at orogen scale 102 km while being sensitive to length scales of slope failure topography sampling and digital elevation model resolution this limits means of automated detection and underlines the importance of local morphologic contrasts for detecting large landslides in the wsa landslide controls on low order drainage include divide lowering and shifting formation of headwater basins and hanging valleys and stream piracy volumes typically mobilized yet still stored in numerous deposits despite high denudation rates are 107 m3 and theoretically equal to 102 years of basin wide debris production from historic shallow landslides lack of absolute ages precludes further estimates deposit size and mature forest cover indicate residence times of 101 104 years on these timescales large landslides require further attention in landscape evolution models of tectonically active orogens

a seismic study of methane hydrate marine bottom simulating reflectors multichannel seismic reflection data have been analyzed from an area of clear bottom simulating reflectors bsrs on the northern cascadia subduction zone margin off vancouver island the reflector at a depth of about 300 m subbottom is interpreted to represent the base of a layer of methane hydrate or clathrate the shallow water depth of 1300 m and the 3600 m long hydrophone array have allowed bsr amplitude versus offset and high resolution velocity analysis as well as modelling of vertical incidence data the results of all three types of analysis can be best explained by a 10 to 30 m thick high velocity layer located immediately above the bsr about 300 m below the seafloor having a sharp base and transitional top in the layer about one third of the sediment pore spaces must be filled with hydrate ice there is no seismically detectable free gas beneath the bsrs these results put important constraints on models for the distribution and formation of bsr hydrate

an overview of recent large catastrophic landslides in northern british columbia canada at least thirty eight large catastrophic landslides each either larger than 0 5 m m 3 or longer than 1 km have occurred in northern british columbia in the last three decades the landslides include low gradient flowslides in cohesive sediments long runout rock slides rock avalanches and complex rock slide flows the flowslides have occurred in a variety of sediments including glaciolacustrine silt clay rich till and clay rich colluvium the rock failures have happened in weak shale overlain by sandstone and volcanic rocks the frequency of large landslides in northern british columbia appears to be increasing suggesting a link to climate change d 2005 elsevier b v all rights reserved

giant landslides topography and erosion abstract distributions of slope angles in tectonically active mountain belts point to the development of threshold conditions where hillslopes attain a critical inclination or height at which they fail readily because of limitations in material strength it has been proposed that hillslopes adjust to rapid uplift and bedrock incision through an increase in the rate of relief limiting landsliding rather than gradual slope steepening here we test this concept by investigating the relationship between mean local relief h which we take to be a proxy of long term erosion rates e and the occurrence of over 300 of the largest v 10 8 m 3 terrestrial landslides on earth we find that nearly two thirds of these giant landslides have occurred in the steepest 5 of the earth s land surface where relief is close to its proposed upper strength limit they are primarily located in deeply incised valleys along fault bounded fringes of active mountain belts and in volcanic arcs this distribution coincides with areas of high long term erosion rates 4 mm yr 1 confirming that giant landslides contribute to rapid denudation of mountains most of the eroded volume is concentrated in the smallest but steepest parts of mountain belts and volcanic arcs first order estimates of minimum erosion rates accomplished by the largest landslides are 0 01 mm yr 1 these rates are between 1 and 10 of the late pleistocene to holocene mean erosion rates in a given area importantly the landslide erosion rates show a nonlinear increase with mean local relief suggesting that the contribution of giant landslides in total and per event increases significantly with increasing overall erosion rates however giant landslides also occur in areas of lower than average relief h 300 700 m irrespective of whether threshold hillslopes have developed or not factors contributing to these failures include soft rocks extensive low angle discontinuities high rates of fluvial bedrock incision and tectonically driven deformation and slope loading

oxygen ion precipitation in the martian atmosphere and its relation with the crustal magnetic fields without a global intrinsic magnetic field oxygen ions in the martian atmospheric corona can be picked up by the solar wind directly the majority of the pickup ions escape while some can precipitate into the atmosphere producing sputtering of atmospheric constituents which may play a significant role in the loss of neutral atmosphere with its widely distributed crustal magnetic fields mars is unique while it has been shown that mars s crustal fields can alter the global distribution of escaping ions little is known about the influence of the crustal fields on the spatial distribution and energy deposition of precipitating pickup ions in this paper the global distribution and energy spectrum of the precipitating pickup oxygen ions are calculated using the test particle method in the electric and magnetic fields set up by mhd simulation cases of different crustal field conditions are compared to show the influence of the crustal fields on the oxygen ion precipitation we find using a test particle code that the crustal fields likely change the spatial distribution of the precipitation resulting in irregularly distributed low energy ion precipitation parches and wide high energy ion precipitation belts on both the dayside and nightside the crustal fields increase o ion precipitation substantially enhancing energy deposition especially on the nightside our results imply that atmospheric sputtering and accompanying neutral escape might happen globally and may be enhanced by a factor of almost 2 with the presence of the crustal magnetic fields

comparison of gpr 2d resistivity and traditional techniques for the subsurface exploration of the oschingen landslide swabian alb germany abstract numerous rotational and translational slides of different sizes cause considerable economic damage in the swabian alb sw germany and are a challenge for risk assessment the oschingen landslide is a typical example for landslides occurring along the escarpment lithology consists of jurassic sedimentary rocks involving clays overlain by marls and limestones a combination of traditional methods drilling mapping inclinometers and geophysical techniques 2d resistivity ert ground penetrating radar gpr was applied to gain knowledge about the thickness and internal structure of the landslide the drillings and penetration tests provided point information on landslide extent structure and material involved in general all inclinometers showed very little movement if at all the gpr results were affected by strong signal attenuation and by overhead reflections from the nearby woods despite these general obstacles for the application of gpr on landslides near surface sediment structures were detected in the 2d resistivity sections higher resistive limestone blocks reaching 10 15 m in thickness could be clearly distinguished from the underlying bedrock the detailed two dimensional data of the electrical resistivity tomography ert along with the rather high survey speed turned out to be the best choice to gain detailed spatial information on thickness and extent of the slope movement the measured profiles coincide with the gpr data and correspond to borehole data surprisingly all results from the applied methods clearly detected the absence of large landslide blocks in the north west of the study area this finding could not be concluded from local geomorphology of this area regarding the current landslide displacement derived from the inclinometer measurements the large landslide blocks seem to be dormant during the measured period

the failure mechanism of a late glacial sturzstrom in the subalpine molasse leckner valley vorarlberg austria a number of prehistoric landslides and rock avalanches occurred in the folded and faulted section of the molasse zone in vorarlberg austria some developed into a sturzstrom defined as a rapidly moving fluidised mass movement of large volumes of rock derived from the disintegration of a falling rock mass that spread under the influence of gravity their impact on the landscape usually is related to obstruction of rivers and valleys in this paper we analyse the geomorphology and the failure mechanism of a relative small sturzstrom the failure mechanism can be described as a buckling failure the morphological situation indicates that failure took place after local deglaciation by the end of the upper wurm the period of failure coincides with glacial and ice marginal remnants which developed between 15 000 and 14 600 bp the lithological sequence and rock structure as well as the impact of the processes related to the former glacial environment were major causal conditions the rock sequence consists of conglomerates sandstone layers and marls next to glacial scouring which increased the inclination of the valley slopes the effect of late glacial unloading and postglacial processes such as weathering and fluvial erosion subsequently weakened the mass rock fabric until failure occurred discontinuity orientation measurements geostructural and geomechanical conditions and the former hydrological and geomorphological conditions support bucklings failure in fact three hinge buckling may have occurred the frontal section of the sturzstrom consists mainly of large conglomerate blocks averaging 1 5 m3 in volume although megablocks reaching of up to 4000 m3 are present as well the volume of the entire sturzstrom equals approximately 10 107 m3 present activity is only restricted to minor rock falls derived from the conglomerates and mudflows originating from the marl layers

seismic and sequence stratigraphy of the central western continental margin of india late quaternary evolution abstract seismic and sequence stratigraphic architecture of the central western continental margin of india between coondapur and south of mangalore has been investigated with shallow seismic data seismic stratigraphic analysis defined nine seismic units that are configured in a major type 1 depositional sequence possibly related to fourth order eustatic sea level changes comprising regressive lowstand transgressive and highstand systems tracts the late quaternary evolution of the continental margin took place under the influence of an asymmetric relative fourth order sea level cycle punctuated by higher frequency cycles these cycles of minor order were characterised by rapid sea level rises and gradual sea level falls that generated depositional sequences spanning different time scales during the regressive periods dipping strata were developed while erosional surfaces and incised valleys were formed during the lowstands of sea level terraces v shaped depressions lagoon like structures observed on the outer continental shelf are the result of the transgressive period in the study area we have recognised a complex erosional surface that records a long time span during the relative sea level fall regressive period and the following sea level lowstand and has been reworked during the last transgression we also infer that sedimentation processes changed from siliciclastic sedimentation to carbonate sedimentation and again to siliciclastic sedimentation marking an important phase in the late quaternary evolution of the western continental shelf of india we attribute this to an abrupt climate change at the end of the oxygen isotope stage 2 between the last glacial maximum and the bolling allerod event 14 000 yr bp this sensitive climate change warming favoured the formation of reefs at various depths on the shelf besides the development of fifty fathom flat a carbonate platform on the outer shelf off bombay developed prior to 8300 yr bp the highstand systems tracts were deposited after the sea level reached its present position

potential distribution of subsurface methane in the sediments of the eastern arabian sea and its possible implications high resolution shallow seismic reflection data obtained in the continental shelf sediments off western india from 10 n to 22 n reveal the characteristic anomalous seismic signatures in the form of acoustic maskings of methane rich horizons a conservative estimate of the potential subsurface methane in these gas charged sediments is of the order of 2 6 tg and its contribution to the atmosphere with an annual flux of 0 039 tg ch4 appears to be quite significant from our limited results coupled with worldwide reports it is concluded that the seepage of methane 8 to 65 tg through the seabed of the continental shelves worldwide cannot be ignored for the estimation of global oceanic flux of methane and its budget

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

10be exposure ages of a rock avalanche and a late glacial moraine in alta valtellina italian alps abstract a rock avalanche deposit was investigated in order to understand the chronological evolution of geological hazards and to evaluate the interaction of the triggering geodynamic processes in the valley val viola italian alps the deposit is situated west of the alpe dosde in a permafrost area with deep seated gravitational deformations dsgd along a tectonic line based on its geomorphologic context the rock avalanche was first interpreted as a result of slope stress release without exact timing this hypothesis was tested by measuring the 10 be exposure date of quartz from one boulder from the rock avalanche the age of 7430 460 years places the event in the early holocene the timing of the last deglaciation was constrained using the inner late glacial moraine of a moraine doublet in the valley alpe dosde situated at an altitude between 2140 and 2120 m a s l west of the rock avalanche the 10 be concentrations of quartz yield minimum exposure ages of 11 480 670 and 10 850 820 years different proposals for potential triggering factors of the rock avalanche include a melting of the local valley glacier and slope stress release in the val viola likely to play a minor role as trigger because of the time delay between the deglaciation and the rock avalanche event more likely are b enhanced crustal seismicity induced by post glacial regional isostatic glacial rebound coupled with tectonic stress or and c climate conditions with higher temperatures around 7430 460 years resulting in an upwards movement of the permafrost limit and destabilization of the rock walls

application of field geophysics in geomorphology advances and limitations exemplified by case studies abstract during the last decade the use of geophysical techniques has become popular in many geomorphological studies however the correct handling of geophysical instruments and the subsequent processing of the data they yield are difficult tasks furthermore the description and interpretation of geomorphological settings to which they apply can significantly influence the data gathering and subsequent modelling procedure e g achieving a maximum depth of 30 m requires a certain profile length and geophone spacing or a particular frequency of antenna for more than three decades geophysical techniques have been successfully applied for example in permafrost studies however in many cases complex or more heterogeneous subsurface structures could not be adequately interpreted due to limited computer facilities and time consuming calculations as a result of recent technical improvements geophysical techniques have been applied to a wider spectrum of geomorphological and geological settings this paper aims to present some examples of geomorphological studies that demonstrate the powerful integration of geophysical techniques and highlight some of the limitations of these techniques a focus has been given to the three most frequently used techniques in geomorphology to date namely ground penetrating radar seismic refraction and dc resistivity promising applications are reported for a broad range of landforms and environments such as talus slopes block fields landslides complex valley fill deposits karst and loess covered landforms a qualitative assessment highlights suitable landforms and environments the techniques can help to answer yet unsolved questions in geomorphological research regarding for example sediment thickness and internal structures however based on case studies it can be shown that the use of a single geophysical technique or a single interpretation tool is not recommended for many geomorphological surface and subsurface conditions as this may lead to significant errors in interpretation because of changing physical properties of the subsurface material e g sediment water content in many cases only a combination of two or sometimes even three geophysical methods gives sufficient insight to avoid serious misinterpretation a good practice guide has been framed that provides recommendations to enable the successful application of three important geophysical methods in geomorphology and to help users avoid making serious mistakes

the hattian bala rock avalanche and associated landslides triggered by the kashmir earthquake of 8 october 2005 the kashmir earthquake of the 8 october killed an estimated 87 350 people 25 500 through co seismic landslides the largest landslide associated with the earthquake was the 68 106 m3 hattian bala rock avalanche that destroyed a village and killed around 1000 people the deposit blocks the valley to a depth of 130 m impounding a lake that reached the dam crest in april 2007 an outburst flood now threatens a major settlement 3 km downstream a series of space images reveals landslide clusters in the rock avalanche source area prior to the earthquake the images also reveal a large slow moving landslide with its toe in the lake failure of this landslide may induce dam failure through overtopping and scour eighty five landslides in the hattian bala catchment predate the shaking of 8 october 2005 a further 73 are co seismic with the main shock and 21 postdate it in the period up to october 2006 landslide magnitude frequency distribution plots derived from satellite images allow an assessment of the contribution of seismically triggered events as compared to background rates of activity

landslide dynamics from high resolution aerial photographs a case study from the western carpathians slovakia abstract the ubietova landslide is one of the largest landslide events in the central slovakia neogene volcanic field area its present morphology resulted from several reactivation events the latest one took place in 1977 we applied archive digital photogrammetry to build the historical topography of the landslide area and reconstructed its evolution from 1969 to 1998 at approximately decadal scale four sets of aerial photos of the area taken in 1969 scale 1 16 000 1977 scale 1 14 000 1988 scale 1 17 000 and 1998 scale 1 20 000 were processed using a digital photogrammetric workstation elevation data were extracted from all the photo sets then four high resolution digital elevation models dems were generated and compared particular interest was placed on quantification of vertical ground displacements and volumetric mass redistribution both of them were calculated by subtracting two subsequent dems consequently distribution and temporal variation of the landslide activity over three decades are outlined through differential raster images differential dems and cross sections according to our results the 1977 reactivation event caused considerable vertical displacements up to 5 7 m in the peak areas of depletion and accumulation zones accordingly large volumes of material 148 000 m3 84 000 m3 were redistributed during this event the dynamics of the 1977 reactivation event shows some specific features that are discussed within the broader context besides the new quantitative data reconstruction of 3d topography of the site before and after the 1977 reactivation brought geomorphic evidence that the area was affected by more than one landslide event in the past

holocene reactivations of catastrophic complex flow like landslides in the flysch carpathians czech republic slovakia catastrophic complex flow like landslides cflls are characterised by a deep seated retrogressive landslide of structurally unfavourably oriented rocks and earthflows that occupy the lower slope positions and originate due to the liquefaction of material accumulated on the upper slopes these landslides are locally important geomorphic agents of late quaternary mountain evolution in the flysch belt of the outer western carpathians czech republic slovakia most of the cflls dammed and steepened adjacent valleys radiocarbon dating suggests that a majority of them moved repeatedly throughout the holocene namely approx every 1 2 ka dated events occurred during humid phases of the younger dryas holocene transition 11 5 9 4 cal ka bp atlantic chronozone 7 4 6 6 cal ka bp the beginning of the subboreal chronozone ca 4 6 cal ka bp and primarily within the subatlantic chronozone at ca 2 0 8 cal ka bp 50 of all events our study suggests that slopes based on an unfavourable structural setting and affected by long term deep seated gravitational deformations may produce cflls even if they are located in medium high mountains although our chronological dataset is influenced by the erosion of older landforms most of the dated reactivations correlate with regional increase in precipitation identified by previous palaeoenvironmetal studies

characteristics of pockmarks in the norwegian trench a 3 km wide corridor across the norwegian trench was surveyed in detail with high resolution side scan sonar and subbottom profiler boomer in order to study pockmarks the pockmarks in the norwegian trench are dish shaped depressions found in the soft silty clays they range from 2 m to 300 m in diameter and appear with a maximum density of 40 50 per km2 lineated depressions and strings of small pockmarks were discovered the strings are generally composed of individual pockmarks 10 15 m in diameter each string can be up to 400 m long some medium sized pockmarks 40 50 m in diameter were found in groups often associated with a large parental pockmark the deep towed subbottom profiler records indicated columnar disturbances fountains in the sediments below some of the pockmarks these fountains are interpreted as vents or fissures through which gas or liquids migrate buried pockmarks and anomalies interpreted as boulders possibly gas bubbles trapped in the substrata were also found the recordings bear evidence of gas or liquid migration originating from layers lying beneath the soft clay sequence a large hydrocarbon gas reservoir has recently been found during exploration drilling in the immediate vicinity of the studied pockmark area pockmarks may be indicators of deep lying gas or oil reservoirs and therefore prove interesting features in relation to hydrocarbon prospecting

structural constraints on deep seated slope deformation kinematics abstract a significant sackung type deep seated slope gravitational deformation dsgsd was recognised for the first time by the authors in the middle part of valfurva east of bormio rhaetian alps italy the reconstruction of its kinematics age and state of activity is presented through a detailed description of its morphological geomechanical and structural features an integrated multi disciplinary approach was performed to achieve a clear comprehension of the phenomenon field surveys and aero photo interpretation were carried out in order to clarify the structural geological and geomorphological setting in which the dsgsd developed a kinematic conceptual model of the slope deformation was developed through the analysis of morpho structures of their significance and relationships with lithological markers and quaternary deposits after a geomechanical characterisation of the rock mass involved in the slope deformation numerical modelling was performed to verify the hypotheses made on kinematics and driving factors of the phenomenon the sackung affects pre permian metapelites metabasites and marbles belonging to the upper austroalpine basement of the campo nappe as well as late pleistocene and holocene glacial and rock glacier deposits the deformation started after the late wurmian age 15 000 11 000 years b p and continued until few centuries ago not excluding a present day low rate activity deformation consists in a large oblique sagging along a deep confined sliding surface associated with gravitational reactivation of pre existing late alpine and recent tectonic brittle structures leading to the formation of n s and wnw ese trending gravitational morpho structures the evolution of the wnw ese trending system resulting in asymmetric trenches led to progressive failure of the lower part of the slope during the last 10 000 years as testified by large paleo landslide accumulations and it is still in progress numerical modelling indicates post glacial unloading as the main triggering factor of the slope deformation the importance of this deep seated slope deformation is enhanced by the occurrence of the 30 mm 3 active ruinon landslide in the lower part of the slope such landslide is subjected to rapid evolution and threatens the valley floor establishing an important risk factor connected to human lives and socio economic activities

deep seated landslides affecting monoclinal flysch morphostructure evaluation of lidar derived topography of the highest range of the czech carpathians abstract the recent launch of national scale lidar derived topographic data provides an opportunity for re evaluating the geomorphic imprint of landslides in forested mountains a lidar based inventory of deep seated landslides dsls in the highest part of czech outer western carpathians moravskoslezske beskydy mts reveals that nearly 20 of the territory is affected by ancient dsls rather than the topography itself we show that the geological characteristics of flysch rocks control the density scaling relationships and morphometry of dsls they reveal a strong tendency to clustering in areas with favourable structural conditions such as cataclinal slopes of individual monoclinal ridges formed by thick bedded sandstones in comparison with high mountain areas and regions dominated by weaker lithology e g claystone dominated flysch sandstone dominated monoclinal structure of the moravskoslezske beskydy mts features predominantly short travelled dsls that are arrested on slopes and thus reveal a higher slope gradient than non landslide terrain finally we propose a conceptual model for the evolution of dsls on monoclinal flysch morphostructures particularly where coherent sandstone caps overlie weak claystone siltstone dominated flysch in these conditions we distinguish between low and high monoclinal ridges where the former is capped by relatively thin sandstones overlying claystone formations and sandstones predominate in the structure of the latter we show that the density of dsls on the cataclinal dip slopes is similar on both types of monoclinal ridges but that major differences exist in the evolution of anaclinal escarpment slopes here low monoclinal ridges are highly affected by dsls but escarpments of high monoclinal ridges are nearly devoid of any dsls

multiple origins of methane in the earth methane occurrences in the earth s crust are predominantly of biogenic origin i e their ultimate source is biologically formed organic matter methane can also form through inorganic reactions and is consequently termed abiogenic biogenic methanes can either form through bacterial or thermogenic processes bacterial processes follow a co2 reduction and or fermentation pathway the fermentation processes are quantitatively more important in recent fresh sediments and swamps methane formed by co2 reduction however is most common in older sediments and commercial gasfields temperature organic substrate and age may be the major factors controlling the relative importance of the two pathways stable isotope concentrations in thermogenic methanes seem to be controlled by the extent of conversion of organic matter the timing of gas expulsion and trapping the different character of methane in individual sedimentary basins may be a result of the geologic history geothermal methanes are most likely derived from pyrolysis of organic matter abiogenic methane occurs in hydrothermal vents and ophiolite complexes inorganic reactions either surficial or deep seated are the likely source of such methanes a uniform mantle origin of methane is not supported by the observed isotope variations in naturally occurring methanes

gas charged sediments on the inner continental shelf off western india abstract high resolution seismic reflection profiles on the inner continental shelf less than 60 m water depth off india from 10 n to 22 n show 5 35 m of weakly stratified acoustically transparent clays at water depths of 15 50 m the subbottom profiles are characterized by anomalous seismic signatures in the form of acoustic maskings these extend from the underlying late pleistocene unconformity often stretching along the bedding planes and occasionally surfacing on the sea bed these acoustic maskings could be due to shallow hydrocarbon gases mainly methane which might have been derived from biogenic sources or geothermal processes or both

geological and geomorphological characteristics of landslides triggered by the 2004 mid niigta prefecture earthquake in japan abstract the 2004 mid niigta prefecture earthquake mjma 6 8 triggered more than one thousand landslides in the miocene to quaternary sedimentary rocks in japan the most common landslides were shallow disrupted landslides on steep slopes which has been common in many previous disastrous earthquakes in the world the mid niigta prefecture earthquake also triggered more than one hundred deep landslides providing valuable information on the conditions for their occurrence a field investigation and the interpretation of aerial photographs taken before and after the earthquake suggest that reactivation of existing landslides and undercutting of slopes are the most important factors for deep landslides to be triggered by earthquakes in addition planar sliding surfaces seem to be essential for the generation of catastrophic landslides triggered by this earthquake planar bedding parallel sliding surfaces were formed at the boundary between the overlying permeable sandstone and underlying siltstone or along the bedding planes of alternating beds of sandstone and siltstone sliding surfaces along the slope parallel oxidation front were formed in the area of black mudstone new landslides rockslide avalanches occurred with the sliding surfaces in a several cm thick tuff interbedded in siltstone one rockslide avalanche occurred on a slope where buckling deformation preceded the earthquake gentle valley bottom sediments were mobilized in many locations probably because they were saturated and partial liquefaction had occurred due to the earthquake shaking

structural control and types of movements of rock mass in anisotropic rocks case studies in the polish flysch carpathians abstract types of gravitational movements in the flysch carpathians are related to tectonic and lithologic anisotropy of rock massifs this article presents the main types of mass movements in the highly anisotropic flysch massifs lateral spreading and rock flow topple translational rotational and compound sliding and complex type of mass movements which are illustrated by chosen forms described using structural analysis joints faults and other structural planes orientation topple is the typical mass movement for double ridges and top trenches e g gaworzyna in the beskid s decki mts translational landslides with flat structural sliding surfaces typical for shallow forms can develop along bedding planes e g duszatyn western bieszczady mts as well as along joints opuszna gorce mts and fault planes rzeki gorce mts currently used classification of the structural landslides is applied only to translational landslides shearing zones of deep seated landslides are composed of structural sections of joints faults bedding planes and shearing elements consequently most of the carpathian landslides have developed as compound type with non circular sliding zones representing complex movements combined with various types of displacement rotation translation and or topple purely rotational movements with circular failure typical for isotropic material have developed in the flysch where thick bedded hard sandstones are underlain by plastic shales e g mt kostrza in the beskid wyspowy mts the influence of anisotropy of these rocks on sliding surface is significantly reduced and plastic type rocks stimulate rock flow development which is usually later transformed into complex landslides with predominant rotational movement e g rotational landslide with topple and flow elements on mt muronka in the beskid l ski mts compound landsliding on mt lubon wielki beskid wyspowy mts represents an antithetic rotational slide with topple and rotational type movements

shallow gas charged sediments off the indian west coast genesis and distribution abstract geophysical and geochemical surveys were carried out off goa central west coast of india to understand the genesis and distribution of shallow gases in marine sediments shallow gas charged sediments within the water depths of 15 to 40 m are reported all along the west coast and are characterized by gas masking high amplitude and reverse polarity reflections in high resolution seismic sparker data attributed to the presence of free gas these high amplitude reflections gas front are observed within a holocene fine grained wedge shaped sediment package overlying the maximum flooding surface the gas front lies between 1 2 and 5 m below the seabed and demarcates the transition from gas in the dissolved phase to bubble phase when the gas concentration exceeds the saturation level the observed and extrapolated sulfate methane transition zone smtz lies between 0 7 and 2 25 m below the seabed and it is related to the depth of the gas front methane concentration reaches saturation below the smtz and produces a bubble phase which lowers the p wave velocity and produces high amplitude reflection observed in the seismic data depleted carbon isotope ratios as low as 88 9 suggest a microbial origin for the methane in the study area high sulfate reduction rate high concentrations of pore water methane phosphate and ammonium in the shallowest site sasu123 1 at 14 7 m water depth suggest an enhanced availability of reactive organic matter required for microbially mediated biodegradation processes high gas flux in the shallow waters is also indicated by the shallowing of the gas front and the widening of the gas masked zone towards shore the present investigations do not testify the origin of holocene shallow gases either from buried channel deposits or the pleistocene sediments

first measurements of the ionospheric plasma escape from mars before the phobos mission the magnetosphere of mars was relatively unexplored basically all data on the charged particle environment of mars had come from the soviet mars missions mars 2 3 4 and 5 here we report the results of an ion composition experiment on board the soviet phobos 2 spacecraft which allowed us to determine the loss of plasma from the ionosphere of mars because mars has a very small intrinsic magnetic field the ion outflow had been expected to be similar to that of venus surprisingly there were many similarities between the ionospheric outflow from mars and the earth the ion loss from mars results from both ion pick up that results from mass loading of the solar wind in the martian boundary layer and ionospheric o beams of energies up to several kev possibly from upward acceleration processes similar to those observed above the earth s auroral oval a preliminary estimate of the ionospheric outflow from mars indicates that the planet is losing oxygen at a rate of 3 x 1025 ions s 1 this corresponds to an evacuation of its present total atmospheric oxygen content contained in co2 and o2 in less than 100 million years

magnetic field and plasma observations at mars initial results of the mars global surveyor mission the magnetometer and electron reflectometer investigation mag er on the mars global surveyor spacecraft has obtained magnetic field and plasma observations throughout the near mars environment from beyond the influence of mars to just above the surface at an altitude of 100 kilometers the solar wind interaction with mars is in many ways similar to that at venus and at an active comet that is primarily an ionospheric atmospheric interaction no significant planetary magnetic field of global scale has been detected to date 2 1021 gauss cubic centimeter but here the discovery of multiple magnetic anomalies of small spatial scale in the crust of mars is reported

temporal behavior of deep seated gravitational slope deformations a review abstract deep seated gravitational slope deformations dsgsds are slow moving hillslope scale mass movements featuring characteristic landforms such as double crested ridges and upslope facing scarps that occur in diverse landscapes throughout the world although these deformations have been studied since the 1960s significant insights to the rates of dsgsds have only been gained within the last two decades owing to progress in geochronology remote sensing and instrumental monitoring absolute age and monitoring data indicate that dsgsd movements are observable over long term 102 years and short term future research directions include constraining the lifespan of dsgsds with absolute age dating and precise high resolution monitoring of spatio temporal displacement across dsgsd bodies it is of great importance to include absolute time scales in the numerical models of dsgsds furthermore combining remote sensing techniques such as synthetic aperture radar interferometry with high resolution lidar scanning and near surface geophysics offers a promising toolkit for collecting very detailed and accurate data on the short term deformation rates of dsgsds

catastrophic slope failure and its origins case of the may 2010 girova mountain long runout rockslide czech republic abstract one of the largest long runout landslides in the modern history of the czech republic originated on the southern slopes of the girova mountain outer western carpathians at the end of extreme rainfalls in may 2010 the structurally predisposed girova mountain rockslide occurred very quickly within fault weakened deeply weathered flysch bedrock its main phase during which a wedge like block collapsed in the upper part of slope lasted for a few hours the overloaded slope collapsed and its motion lasted for the following 3 days the may 2010 girova mountain rockslide is an excellent case of a recurrent long runout landslide nested within a deep seated gravitational slope deformation with a long history of late quaternary mass movements the chronology of slope failures within the studied slope was reconstructed by means of radiocarbon dating and dendrogeomorphological analysis at least one holocene long runout landslide 7 4 cal ka bp and several smaller failures 1 5 and 0 6 cal ka bp preceded this recent catastrophic failure dendrogeomorphological analysis showed that the failure had been preceded by at least 80 year long creep movement that accelerated over the years due to extreme rainfall events despite the fact that extreme precipitation of may 2010 represented the last incremental change before catastrophic collapse of the slope its main reason was gradual weakening of rock massif and concentrated creeping with some accelerated phases in the upper part of the slope deformation

10be dating reveals pronounced mid to late holocene activity of deep seated landslides in the highest part of the czech flysch carpathians abstract although the highest part of the czech outer western carpathians lacks significant recent landslide activity the vast area 20 of their territory is occupied by relict deep seated landslides and deep seated gravitational slope deformations dating these deformations might help to determine degrees of present day landslide hazard in that area based on the 10be exposure dating of eight rocky scarps and walls of ridge top trenches we estimated the minimal ages of the deep seated landslides dsls and one deep seated gravitational slope deformation dsgsd in the satina river basin in the moravskoslezske beskydy mts the obtained ages 9 7 2 9 ka suggest holocene slope instability in the area with a pronounced cluster of ages spanning from 6 0 to 2 9 ka except for one dsl the ages reveal rather episodic activity of gravitational movements mid to early late holocene activity of large landslides in the study area corresponds to the ages of several previously dated landslides both in an adjacent region as well as within the central european context with respect to the historical quiescence of the dsls and dsgsds in the area and because the slopes have not been destabilized even during the most extreme hydrometeorological events within the last few decades we infer that the hydrometeorological thresholds necessary for their activation are seldom exceeded in this area therefore the highest parts of the carpathians built by rigid thick bedded lithology reveal a rather lower frequency of events in comparison with adjacent parts formed by claystone dominated flysch where several large dsls originated in the last few decades as a consequence of heavy rainfalls

sackung and enigmatic mass movement folds on a structurally controlled mountain ridge abstract the recently emerged concept of slope tectonics suggests that mass movement processes can produce structures similar in morphological expression to that of extensional strike slip and compressional tectonic deformations further there has long been debate about the tectonic or gravitational origin of lineaments found on hillslopes here we present cases of where geological structure and inherited tectonic structures have preconditioned the development of mass movements and creation of slope tectonic features on a monoclinal ridge smrk mt in the outer western carpathians czechia geomorphic mapping from lidar derived topography structural measurements electrical resistivity tomography and ground penetrating radar were used to map synthetic and antithetic scarps thrusts and folds and assess their relation to geological and tectonic structures the scarps are found to be strongly related to transverse nnw to nne trending inherited normal and strike slip faults and mainly cross cut the topography of the mountain ridge some of the folds are thought to have originated from buckling or compression in the distal parts of landslides in other places transpressional folds have developed oblique to major lateral shear surfaces interpreted to be sackung mass movement scarps that have been inherited from tectonic faults the transpressional folds developed due to localized contraction along bends in the lateral shear surface as mass movement proceeded ramp flat thrust folds developed in the compressional parts of landslides where the landslide intersects with slope parallel sackung and or inherited fault planes inclined to the slope altogether this study demonstrates a connection between kinematics of deep seated gravitational slope deformations dsgsds shallower landslides and the origin of transpressive ramp flat thrust and detachment structures in rock slopes

fossil and recent debris flows in medium high mountains moravskoslezske beskydy mts czech republic abstract the significance of debris flows for the morphogenesis of the medium high mountains of central europe has long been neglected herein we provide evidence from the moravskoslezske beskydy mountains flysch western carpathians czech republic where fossil pleistocene debris flow events in spite of their low recent activity were important erosion and accumulation agents in shaping the mountainous terrain geomorphological and sedimentological analyses helped to differentiate between two classes of debris flow deposits deposits of the 1st class are relatively voluminous contemporary terraced landforms which originated in the pleistocene transport limited conditions recent activity of debris flows presented by the 2nd class accumulations is characterized by the presence of low magnitude events mostly originated during the reworking of older diamictons the inheritance of large volumes of old debris flow diamictons in steep mountainous terrain is the evidence of slow erosional transformation of the last glacial landforms pointing to the fact that recent topography of the mountains is not in full equilibrium with contemporary climatic and environmental conditions

some forms of mountain peaks in the canadian rockies controlled by their rock structure abstract different mountain shapes in sedimentary sequences in the canadian rockies were enhanced by glacial erosion and have been modified post glacially by gravity driven slope processes slope modification by both glacial erosion and post glaciation landslides is related to slope geometry and rock structure particularly bedding dip five mountain peak shapes in monoclinal sequences each fall into different ranges of bedding dips 1 castellate and 2 matterhorn mountains occur in sub horizontal beds and their slopes are generally 35 65 and oblique to both bedding and joints 3 cuestas develop in gently to moderately dipping beds dip slopes and steeper normal escarpments form their cataclinal and anaclinal sides respectively with the dihedral angle between them about 90 4 hogbacks in moderately to steeply dipping beds have similar slope angles on both cataclinal and anaclinal slopes cataclinal slopes are either dip slopes or underdip slopes but anaclinal slopes are often steepened escarpments the dihedral angle between the slopes is usually slope gradients on a sample of 34 peaks are closely related to landslides particularly rock slides and rock topples these landslide modes are controlled by bedding dips

gas venting and late quaternary sedimentation in the persian arabian gulf abstract high resolution 3 5 khz echo sounding profiles and piston cores were used to reconstruct the microtopography and late quaternary depositional history of the persian gulf perversive throughout the seafloor of the gulf is an extensive network of pockmarks formed by seepages of thermogenic gas these gas seeps and bottom water exiting the gulf via the strait of hormuz are the most significant processes controlling present day sedimentation in the region erosion by these seeps has been so intense in the baiban shelf in the strait of hormuz as to create a hoodoo like terrain on the outer shelf the surfical geology of the gulf documents a short lived transgression 29 400 to 22 800 years ago during the wisconsin regression which began 125 000 years ago the wisconsin regressive maxima when sea level dropped to 120 130 m about 21 000 20 000 years ago and the climate was dry and eolian and paralic sedimentation characterized the gulf the holocene transgression 18 000 to 12 000 years ago when the climate was more humid than during the climax of the wisconsin regression a dry phase 12 000 to 9000 years ago when the persian gulf was a site of eolian and carbonate deposition and the present sediment cycle during the last 9000 years under a more humid regime it was during the present cycle that southeast trending marl lobes were deposited off iran arabia acquired its hyper arid climate about 3000 years ago and the gulf attained its present configuration about 1000 years ago as a result of the construction of the tigris euphrates delta at its head and tectonism and aggradation along its arabian and iranian flanks

model investigation of the influence of the crustal magnetic field on the oxygen ion distribution in the near martian tail 1 to investigate the influence of the martian crustal magnetic field on the acceleration and escape of the planetary ions in the near tail region the distributions of planetary oxygen ions are studied by means of test particle simulation in an electromagnetic environment created by a recent multispecies magnetohydrodynamics mhd simulation of the solar wind interaction with mars with crustal field included or excluded results under different crustal field conditions are compared to determine the effects of crustal field it is found that when crustal field is present draped magnetic field lines are replaced by closed field lines in the near tail region and the electric field is also intensified because of the hall effect as a result the oxygen ion distribution reveals distinct stream structures in the tail region when crustal field is included with one hot stream at the central tail and two cold streams at the flank of the tail some energetic ions inside the hot stream are accelerated toward the planet instead of escaping downstream

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

the beinn alligin rock avalanche nw scotland cosmogenic 10be dating interpretation and significance a tongue of very coarse rockslide debris that extends 1 25km downvalley below beinn alligin in nw scotland has been variously interpreted as a glacier cored rock glacier landslide debris redistributed by glacier ice or an excess runout landslide exposure dating with cosmogenic 10be demonstrates that the the debris mass was emplaced at 3950 320 yr bp and therefore was not associated with glacier ice calculations based on frictional considerations imply that the feature is an excess runout rock avalanche sturzstrom deposit the morphological characteristics of the deposit appear consistent with movement by grainflow or fragmental flow failure is inferred to reflect time dependent paraglacial stress release and consequent propagation of an internal joint network but may have been triggered by seismic activity the late holocene age of failure implies persistence of the e ects of paraglacial stress release over a time scale of several millennia

a gravitational spreading origin for the socompa debris avalanche abstract socompa volcano arguably provides the world s best exposed example of a sector collapse derived debris avalanche deposit new observations lead us to re interpret the origin of the sector collapse we show that it was triggered by failure of active thrust anticlines in sediments and ignimbrites underlying the volcano the thrust anticlines were a result of gravitational spreading of substrata under the volcano load about 80 of the resulting avalanche deposit is composed of substrata formerly residing under the volcano and in the anticlines the collapse scar can be traced up to 5 km from the edifice truncating two spreading related anticlines which collapsed in the event outcrops near the volcano preserve evidence of edifice material being carried along on top of mobilised substrata on the north side of the scar the avalanche motion was initially at right angles to the failure edge structural relations indicate that immediately prior to collapse the substrata disintegrated became effectively liquidised and were ejected from beneath the edifice catastrophic mobilisation of substrata probably resulted from breakdown of ignimbrite clasts and cement it may have occurred through progressive rock fracture by high shear strain during spreading material ejected from under socompa formed a layer on which volcanic edifice debris was transported this interpretation of events explains the puzzling observation that avalanche units with the lowest gravitational potential energy moved the furthest it can also account for avalanche motion normal to the collapse scar walls ignimbrites and other rock types probably capable of similar behaviour underlie many other volcanoes identification of spreading at other sites could therefore be a first step towards assessment of the potential for this style of catastrophic sector collapse

the giant paleolandslide deposits of tafi del valle tucuman province argentina abstract in the present study seven landslide deposits that took place during the pleistocene in the northern part of tafi del valle tucuman province argentina are described the recognition and mapping of them were carried out using satellite images aerial photograph interpretation and field survey the analysis of the area covered by the deposits and their runout distances were undertaken using aerial photographs at a scale of 1 50 000 and the software image tool all the deposits overcome the 106 m3 of volume with smaller coefficients of friction at 0 22 that gives an idea of the great mobility that they had reaching average speeds 100 km h these deposits could have originated as a consequence of a combination of internal slow deformation and fragmentation under periglacial conditions followed by a sudden collapse of the rock mass generated by strong earthquakes of magnitudes 6 at the base of the cumbres calchaquies ranges

geophysical anatomy of counter slope scarps in sedimentary flysch rocks outer western carpathians abstract a multidisciplinary geophysical survey consisting of electrical resistivity tomography ert ground penetrating radar gpr shallow seismic refraction ssr and gravity survey gs was used to investigate the counter slope scarps one of the typical manifestations of the relaxed zones of rock massifs and the possible initial stages of deep seated landslides dsls two upper parts of the extensive dsls within the moravskoslezske beskydy mountains outer western carpathians owc built by the sedimentary flysch rock were chosen as the testing sites a combined geophysical survey on the flysch rocks was performed on both localities to enhance our present findings the survey revealed that the ert is able to reliably detect underground discontinuities which are manifested at the ground surface by one of the typical landforms tension cracks trenches pseudokarst sinkholes double crested ridges and counter slope scarps previous studies suggested that bedrock discontinuities should be depicted by high resistivity features within ert surveying according to ssr and gs expected zones of weakened rock massif were not confirmed directly underneath the superficial landforms but they were shifted based on the ssr and gs measurements the depicted high contrast transitions between high and low resistivity domains within the ert profiles were newly identified as possible manifestation of bedrock discontinuities the results of gpr measurements give only limited information on the sedimentary flysch rocks due to shallow penetrating depth and locally strong signal attenuation the combined results of multidisciplinary geophysical surveying confirmed an importance of employing more than one geophysical technique for integrated interpretations of measured data integrated interpretations of the measured geophysical data provided a new insight into massif disintegration and the geomorphic origin of the landforms related to the dsl

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

an introductory review on gravitational deformation induced structures fabrics and modeling abstract recent studies have pointed out a similarity between tectonics and slope tectonic induced structures numerous studies have demonstrated that structures and fabrics previously interpreted as of purely geodynamical origin are instead the result of large slope deformation and this led in the past to erroneous interpretations nevertheless their limit seems not clearly defined but it is somehow transitional some studies point out continuity between failures developing at surface with upper crust movements in this contribution the main studies which examine the link between rock structures and slope movements are reviewed the aspects regarding model and scale of observation are discussed together with the role of pre existing weaknesses in the rock mass as slope failures can develop through progressive failure structures and their changes in time and space can be recognized furthermore recognition of the origin of these structures can help in avoiding misinterpretations of regional geology this also suggests the importance of integrating different slope movement classifications based on distribution and pattern of deformation and the application of structural geology techniques a structural geology approach in the landslide community is a tool that can greatly support the hazard quantification and related risks because most of the physical parameters which are used for landslide modeling are derived from geotechnical tests or the emerging geophysical approaches

morphology and internal structure of a dormant landslide in a hilly area the collinabos landslide belgium abstract this study attempts to reconstruct the history of the collinabos landslide a landslide with a fresh morphology that is representative for more than 150 dormant deep seated 3 m landslides in the flemish ardennes belgium a geomorphological map was created based on lidar light detection and ranging derived maps and detailed field surveys the map showed that the landslide consisted of three zones with significant differences in surface topography the northern landslide zone 1 is characterised by at least five reverse slopes whereas zones 2 and 3 the southern landslide zones have only two reverse slopes and a convex foot electric resistivity profiles measured in zones 1 and 2 revealed that the differences in surface topography were not related to differences in internal structure as both parts of the landslide were initiated as a rotational earth slide with a surface of rupture at 15 m deep where the displaced material broke apart in two blocks however two shear surfaces of reactivations within landslide debris were only distinguished in the accumulation area of zone 1 the observed differences in surface morphology can be caused by a temporary conversion of a forest into cropland in zone 2 it is suggested that reverse slopes of smaller reactivations within landslide debris were obliterated during the agricultural activities ams radiocarbon dating of organic material found in ponds located in reverse slopes generally resulted in relatively recent dates i e 1400 1950 cal ad suggesting that several of the small local reactivations occurred in that period one dating at 8700 8440 cal bp of organic matter collected in a reverse slope in zone 1 suggests that an initiation under periglacial conditions cannot be excluded for the collinabos landslide by combining different technologies this study provides valuable information for a better understanding of dormant landslides

mountain slope deformations along thrust fronts in jointed limestone an equivalent continuum modelling approach abstract engineering geology studies of natural slope stability have rarely relied on continuum modelling of discontinuous rock mass or the use of conventional constitutive laws in fem or fdm codes the paper proposes the use of numerical modelling based on a practical equivalent continuum approach for analysing the deep seated gravitational slope deformations dsgsd observed in the thrust front area of the lepini mountains italian apennines the dsgsd phenomena affect a carbonate ridge close to the villages of san sebastiano and sgurgola inducing a significant risk this study began with the construction of engineering geology sections by distinguishing lithotechnical units on the basis of both site and geomechanical parameters considering geological and geomorphological field evidence the numerical simulations validated the assumed kinematic model of the slope these simulations aimed at estimating the instability of the affected rock masses by identifying a critical mass beyond which ongoing deformations become morphologically evident on the involved slope a ratio of the weight of a critical mass which is the minimum mass required to produce some geomorphological evidence to the weight of the mass involved in the gravitational slope deformations was calculated in order to quantitatively assess the evolutionary stage of the ongoing deformations the calculated ratio demonstrates a more advanced evolutionary stage for the slope sector near the village of sgurgola due to its particular geological setting than the one near the village of san sebastiano

large rock slope failures in the highlands of scotland characterisation causes and spatial distribution abstract a comprehensive database of larger rock slope failures rsfs has been compiled and characterised for a whole mountain range possibly for the first time apart from iceland most rsfs in the scottish highlands occurred soon after deglaciation a threshold size of 0 25 km 2 focuses on rsfs which contribute significantly to gross erosion in the glacial paraglacial cycle and on the spatial concentration of this poorly recognised process database verification indicates that at least 90 of the total extant population in the highlands is covered standard mass movement typologies are broadly applicable but require some refinement to characterise rsfs in a passive margin glaciated mountain range comprised mainly of ancient metasediments most larger rsfs here are complex and difficult to categorise a continuum from cataclasmic failures including rock avalanches through arrested translational slides to almost in situ slope deformations is identified the prevailing modes of large rsf are arrested short travel translational sliding and gravitational sagging cataclasmic failure is rare and sub cataclasmic outcomes are more evident a significant class of deformations exhibits compressional rather than extensional features and may be responding to localised glacio isostatic rebound stresses the large rsf population is widely but very unevenly distributed across the main mountain areas 65 are in seven main clusters with the rest non randomly scattered previous glaciological lithological and seismotectonic explanations are insufficient to explain this spatial pattern and overlook the basic engineering geology prerequisites for failure massifs of similar relief and lithology can display intense or sparse rsf incidence geomorphological appraisal suggests an association with recently active glacial breaches of main and secondary watersheds with rsf being scarce or absent in valleys inherited from tertiary uplift and in mountain groups away from the main watersheds valleys which adapted early to ice discharge are seen as stress hardened with their slopes unlikely to reach critical thresholds for failure after subsequent reoccupations by ice concentrated erosion in the last glaciations is most likely to be found close to where breaches are actively forming or enlarging such erosion in the slope foot and valley floor may have daylighted failure planes or generated rebound stresses augmenting those from other endemic sources sufficiently to provoke widespread paraglacial rsf slope stress models for deglaciated valleys and comparative studies in other glaciated mountain ranges are required to test this concept and may assist in geohazard assessments