evolution of the eastern volcanic ridge of the canary islands based on new kar data the results of 64 new k ar age determinations together with 32 previously published ages show that after a period of erosion of the basal complex miocene volcanic activity started around 20 ma in fuerteventura and 15 ma in lanzarote forming a tabular succession of basaltic lavas and pyroclastics with a few salic dykes and plugs this series includes five separate volcanic edifices each one with its own eruptive history in fuerteventura several miocene eruptive cycles have been identified in the central edifice one around 20 17 ma followed by two others centred around 15 and 13 ma in the southern edifice the maximum of activity took place around 16 14 ma whereas in the northern one the main activity occurred between 14 and 12 ma in lanzarote a first cycle of activity took place in the southern edifice between 15 5 and 14 1 ma followed by another between 13 6 and 12 3 ma in the northern edifice three pulses occurred 10 2 8 3 6 6 5 3 and 3 9 3 8 ma an important temporal gap greater in fuerteventura than in lanzarote separates series i from the plio quaternary series ii iii and iv formed by multi vent basaltic emissions in fuerteventura the following eruptive cycles have been identified 5 2 9 2 4 1 8 1 7 0 8 0 4 and 0 1 ma in lanzarote the activity was fairly continuous from 2 7 ma to historic times with a maximum in the lower pleistocene eruptive rates in the series i edifices were on the average 0 1 0 01 km3 ka comparable but slightly smaller than in similar edifices in tenerife and la gomera but much lower than in gran canaria average post miocene eruptive rates were about 0 013 0 027 km3 ka in lanzarote and 0 003 0 007 km3 ka in fuerteventura all these volcanic edifices show a similar general sequence fissural eruptions erosion multi vent volcanism repeated at different periods in different parts of the eastern islands of the canaries the model of growth of the series i edifices is comparable to those in tenerife and la gomera long periods of activity sometimes greater than 6 m y with pulses separated by gaps however salic and intermediate differentiates frequent in tenerife and la gomera are very scarce in these islands the fuerteventura lanzarote ridge shows a decrease in volcanic activity with time and also a certain ssw nne polarity in the temporal development of volcanism

deep seated gravitational slope deformations related landslides and tectonics abstract deep seated gravitational slope deformations and their relationships with tectonic deformation of rocks is considered to examine the viewpoint of tectonics as a causative factor in slope deformation first a distinction is made between the different types of deep seated gravitational slope deformation then the geomorphological and structural effects of the different macrostructural deformations induced by tectonics on the scale of the whole deforming ridge is briefly discussed finally some case studies that represent either verified or possible cases of gravity deformation in response to tectonic activity are used as illustration

benthic assemblage composition on subtidal reefs along a latitudinal gradient in western australia at regional scales the distribution of species and the structure of assemblages vary with latitude within many marine and terrestrial systems the oligotrophic coastal waters of western australia wa support highly speciose and endemic assemblages yet spatial patterns in benthic structure are currently poorly known we examined benthic assemblage composition along a latitudinal gradient of 28 5 33 5 s and a depth gradient of 14 62 m on subtidal reefs in warm temperate wa we surveyed benthos using a remotely triggered digital stills camera in total we sampled macroalgae and sessile invertebrates at 201 sites spread across four locations percent cover of coarse taxonomic groups and dominant species was estimated from over 2000 photoquadrat samples we recorded significant differences in benthic assemblage composition between locations and along depth gradients within each location however the magnitude of change with depth was not consistent between locations and shifts in assemblage composition along the depth gradients were not as pronounced as expected the percent cover of all dominant benthic groupings differed between locations and several key taxa such as the kelp scytothalia dorycarpa brown foliose macroalgae hard corals and sponges changed predictably along the latitudinal gradient our study adopted a coarse taxonomic but assemblage wide approach to describing macrobenthic assemblages and clear differences between locations and depths were detected the surveys have provided baseline data on broad scale ecosystem structure against which to detect future ecological change

spatial variation patterns of subtidal seaweed assemblages along a subtropical oceanic archipelago thermal gradient vs herbivore pressure abstract the structure and composition of subtidal rocky seaweed assemblages were studied at 69 sites on the canary islands northeastern atlantic this group of islands are situated at the southern boundary of the warm temperate region and adjacent to the cold waters from the northwest african coastal upwelling which creates a difference of almost 2 c in surface seawater temperature from the eastern to the western islands this thermal variation allows an examination of the transition between the warm temperate and the tropical regions along this longitudinal gradient together with the hypothesised fucales dominated assemblages towards the eastern islands in contrast to the dictyotales dominated assemblages towards the western ones environmental and biological parameters were considered in order to investigate which were the main factors explaining spatial variation along the gradient in a multi scaled approach although seventy nine macroalgae were identified 87 63 of the total mean cover was due to six taxa lobophora variegata nongeniculate corallines canistrocarpus cervicornis jania adhaerens cystoseira abies marina and pseudolithoderma adriaticum at a large scale sea urchin density explained the highest variation in seaweed assemblages 26 94 and its pattern of distribution across the islands the expected pattern of distribution according to the upwelling distance only occurred in restricted areas of the canarian archipelago in absence of herbivore pressure and habitat degradation spatial variations within islands medium scale were mainly related to wave exposure while at a small scale these were mostly due to the degree of sedimentation

landslide development in a coastal valley in northern spain conditioning factors and temporal occurrence abstract sixty five landslides have been mapped in the meredal valley carved in one of the asturian precoastal ranges on mesozoic bedrock from a genetic point of view two groups of landslides can be distinguished landslides developed mainly over triassic lutites complex movements flows and rockslides and landslides developed from calcareous cliffs rock avalanches many of them are relict landslides although evidence of activity can be recognized as a result of a partial reactivation of some of the landslides four chronological classes have been established according to geomorphological criteria and the degree of preservation of the landslides a lateral plugging deposit provides a minimum age of 5050 40 b p for the oldest class in the same way a stalactite gives to the third class of landslides a minimum age of 3392 128 b p the origin of landslides can be related to the plastic behavior of lutite and the permeability of the overlying limestone which allows vertical seepage of water from a regional point of view landslides could be connected with quaternary fluvial incision processes as well as to holocene high rainfall events

slope deposits in the upper nalon river basin nw spain an approach to a quantitative comparison the upper nalon river basin cantabrian mountains nw spain exhibits a variety of slope processes and deposits including landslides rockfall and soil creep geomorphic maps were used to quantitatively ascertain the relationships between these deposits and topographic characteristics of exposure gradient and altitude at the nodes of a square grid with 250 m spacing n 926 a correspondence analysis allows the analysis of qualitative variables lithology and origin of deposit and quantitative variables altitude with a class interval of 200 m and gradient in 10 classes the results suggest that lithology is the main conditioning factor of the differences and similarities between deposits

evaluation of prediction capability of the artificial neural networks for mapping landslide susceptibility in the turbolo river catchment northern calabria italy abstract landslides are one of the most widespread natural hazards that cause damage to both property and life every year and therefore the spatial distribution of the landslide susceptibility is necessary for planning future developmental activities in this paper the artificial neural network ann technique is tested for developing a landslide susceptibility map in turbolo river catchment north calabria south italy landslides were mapped through air photo interpretation and field surveys by identifying both the landslide depletion zones dzs and accumulation zones azs and relevant geo environmental thematic layers pertaining to landslide predisposing factors were generated using air photo interpretation field surveys and geographic information system gis tools ten predisposing factors were related to the occurrence of landslide lithology faults land use drainage network and a series of topographic factors elevation slope aspect plan curvature topographic wetness index twi and stream power index spi in order to evaluate and validate landslide susceptibility the dzs were divided in two groups using a random partition strategy the first group training set was used to prepare the susceptibility map employing a back propagation learning algorithm in the idrisi taiga software the second group testing set was used to validate the landslide susceptibility model using the confusion matrix and the receiver operating characteristic roc curve the susceptibility map was classified into five susceptibility classes very low low moderate high and very high about 46 of the study area falls in high to very high susceptible classes and most of the dzs mapped 87 3 occur in the same classes the validation results showed satisfactory agreement between the susceptibility map and the dzs locations over 85 of the dzs of the validation set are correctly classified falling in high and very high susceptibility areas also the roc curve had shown an area under curve auc value of 0 90 which demonstrates the robustness and good reliability of the landslide susceptibility model according to these results we conclude that the map produced by the artificial neural network is reliable and the methodology applied in the study produced high performance and satisfactory results which may be useful for land planning policy

objective landslide detection and surface morphology mapping using high resolution airborne laser altimetry a map of extant slope failures is the most basic element of any landslide assessment without an accurate inventory of slope instability it is not possible to analyze the controls on the spatial and temporal patterns of mass movement or the environmental human or geomorphic consequences of slides landslide inventory maps are tedious to compile difficult to make in vegetated terrain using conventional techniques and tend to be subjective in addition most landslide inventories simply outline landslide boundaries and do not offer information about landslide mechanics as manifested by internal deformation features in an alternative approach we constructed accurate high resolution dems from airborne laser altimetry lidar data to characterize a large landslide complex and surrounding terrain near christchurch new zealand one dimensional circular 2 d and spherical 3 d statistics are used to map the local topographic roughness in the dems over a spatial scale of 1 5 to 10 m the bedrock landslide is rougher than adjacent unfailed terrain and any of the statistics can be employed to automatically detect and map the overall slide complex furthermore statistics that include a measure of the local variability of aspect successfully delineate four kinematic units within the gently sloping lower half of the slide features with a minimum size of surface folds that have a wavelength of about 11 to 12 m and amplitude of about 1 m are readily mapped two adjacent earthflows within the landslide complex are distinguished by a contrast in median roughness and texture and continuity of roughness elements the less active of the earthflows has a surface morphology that presumably has been smoothed by surface processes the laplacian operator also accurately maps the kinematic units and the folds and longitudinal levees within and at the margins of the units finally two dimensional power spectra analyses are used to quantify how roughness varies with length scale these results indicate that no dominant length scale of roughness exists for smooth unfailed terrain in contrast zones with different styles of landslide deformation exhibit distinctive spectral peaks that correspond to the scale of deformation features such as the compression folds the topographic based analyses described here may be used to objectively delineate landslide features generate mechanical inferences about landslide behavior and evaluate relatively the recent activity of slides published by elsevier science b v

characterizing structural and lithologic controls on deep seated landsliding implications for topographic relief and landscape evolution in the oregon coast range usa in mountainous areas landslides regulate temporal variations in sediment production and may suppress simple linkages between topographic development and tectonic forcing rates and mechanisms of mass wasting depend on lithology bedrock structure and climatic and tectonic setting these factors tend to vary signifi cantly in active tectonic regions thus clouding our ability to predict how landsliding modulates topographic development over human and geological time scales here we use a novel dem based technique to document the distribution of large landslides in the oregon coast range ocr and quantify how they affect topographic relief we developed an automated algorithm that exploits the distinctive topographic signature specifi cally the relationship between curvature and gradient of large landslides to map their distribution within the gently folded tyee formation eocene deltaicsubmarine ramp sediments in contrast to steep and highly dissected terrain frequently identifi ed as characteristic of the ocr which exhibits steep planar sideslopes and highly curved low gradient ridgetops and valleys terrain prone to large landslides tends to have low values of both drainage density and curvature and gradient values that cluster between 0 16 and 0 44 the distribution of failure dominated terrain in our 10 000 km2 study area is infl uenced by systematic variations in sedimentary facies and bedrock structure the fraction of terrain altered by large landslides 0 1 km2 varies from 5 in the sand rich delta slope and proximal ramp facies southern section of our study area to 25 in the north distal ramp facies coincident with an increase in the thickness of siltstone beds and a decrease in the sandstone siltstone ratio local relief declines progressively northward suggesting that deep seated landsliding is sensitive to the thickness and frequency of low shearstrength siltstone beds and may serve to limit topographic development in the ocr structural controls are superimposed on facies related variations as deep seated landslides are frequently found on slopes whose downslope aspect corresponds to the bedrock dip direction for 1516 strike and dip measurements in our study area we calculated the fraction of proximal terrain 2 5 km altered by deep seated landsliding in the sand rich southern region the proportion of proximal slide dominated terrain increases modestly with bedrock dip in the silt rich northern region terrain altered by deep seated landsliding is pervasive and an increase in dip from 0 to 16 corresponds to a change in the fraction of slide prone terrain from 10 to 28 our technique for mapping large landslides has utility for hazard analysis and land management over million year time scales the progradational character of the tyee formation suggests that continued uplift and exhumation of the ocr should result in a southward propagation of slide prone silt rich distal facies as a result deep seated landsliding will become increasingly prominent and topographic relief in the central and southern ocr will progressively decline whereas spatial variability in climatic or tectonic forcing is often invoked to explain systematic variations in topographic development our results emphasize the importance of structural and intraformation lithologic controls on landsliding as such analyses linking surface processes climate tectonics and landscapes should be couched in the context of diverse geologic and topographic data

application of lidar and discriminant analysis to determine landscape characteristics for different types of slope failures in heavily vegetated steep terrain horseshoe run watershed west virginia abstract a landslide inventory map was created for horseshoe run watershed west virginia using high resolution topographic data obtained from airborne lidar a total of 152 landslides were remotely mapped and classified as planar slides rotational slumps debris flows debris fans debris slides and active slopes based on morphologic characteristics interpreted from lidar derived shaded relief maps with field verification at several locations seven landscape variables were calculated for the watershed from the high resolution 0 5 m topographic data elevation slope angle slope aspect distance from roads distance from streams plan curvature and profile curvature statistical analyses were conducted to determine the mean and standard deviations for each variable and corresponding slope failure type discriminant analyses were conducted on the different types of failed slopes with a maximum 86 accuracy level to determine which landscape characteristics contribute to each type of landslide results from the discriminant analyses indicate that statistically significant differences exist between the failure classes mapped within the watershed and that slope angle slope aspect and landscape curvature are important variables influencing the type of process the results from this study have important implications for predicting where certain types of slope failures may occur based on landscape characteristics

the interaction between active normal faulting and large scale gravitational mass movements revealed by paleoseismological techniques a case study from central italy paleoseismological techniques have been applied to characterize the kinematic behaviour of large scale gravitational phenomena located in proximity of the seismogenic fault responsible for the mw 7 0 1915 avezzano earthquake and to identify evidence of a possible coseismic reactivation the above mentioned techniques were applied to the surface expression of the main sliding planes of the mt serrone gravitational deformation located in the southeastern border of the fucino basin central italy the approach allows us to detect instantaneous events of deformation along the uphill facing scarp these events are testified by the presence of faulted deposits and colluvial wedges the identified and chronologically constrained episodes of rapid displacement can be probably correlated with seismic events determined by the activation of the fucino seismogenic fault affecting the toe of the gravitationally unstable rock mass indeed this fault can produce strong short term dynamic stresses able to trigger the release of local gravitational stress accumulated by mt serrone s large scale gravitational phenomena the applied methodology could allow us to better understand the geometric and kinematic relationships between active tectonic structures and large scale gravitational phenomena it would be more important in seismically active regions since deep seated gravitational slope deformations can evolve into a catastrophic collapse and can strongly increase the level of earthquake induced hazards

volcanic evolution of the island of tenerife canary islands in the light of new k ar data new age determinations from tenerife together with those previously published 93 in all provide a fairly comprehensive picture of the volcanic evolution of the island the oldest volcanic series with ages starting in the late miocene are formed mainly by basalts with some trachytes and phonolites which appear in anaga teno and roque del conde massifs in anaga ne three volcanic cycles occurred one older than 6 5 ma a second one between 6 5 and 4 5 ma with a possible gap between 5 4 and 4 8 ma and a late cycle around 3 6 ma in teno nw after some undated units the activity took place between 6 7 and 4 5 ma with two main series separated by a possible pause between 6 2 and 5 6 ma in the zone of roque del conde s the ages are scattered between 11 6 and 3 5 ma between 3 3 and 1 9 ma the whole island underwent a period of volcanic quiescence and erosion the large canadas volcano made up of basalts trachytes and phonolites was built essentially between 1 9 and 0 2 ma to the ne of this central volcano linking it with anaga is a chain of basaltic emission centers with a peak of activity around 0 8 ma the canadas caldera had several collapse phases associated with large ignimbrite emissions there were at least an older phase more than 1 ma old on the western part of the volcano and a younger one less than 0 6 ma old in the eastern side the two large valleys of guimar and la orotava were formed by large landslides less than 0 8 ma ago and probably before 0 6 ma ago the present canadas caldera was formed by another landslide less than 0 2 ma ago this caldera was later filled by the huge teide volcano which has been active even in historic times during the same period a series of small volcanoes erupted at scattered locations throughout the island the average eruptive rate in tenerife was 0 3 km3 ka with relatively small variations for the different eruptive periods this island and la gomera represent a model of growth by discontinuous pulses of volcanic activity separated by gaps often coinciding with episodes of destruction of the edifices and sometimes extended for several million years the neighbouring gran canaria on the other hand had an initial rapid shield building phase during which more than 90 of the island was built and a series of smaller pulses at a much later period a comparison between these three central islands indicates that the previously postulated westward displacement in time of a gap in the volcanic activity is valid only as a first approximation several gaps are present on each island overlapping in time and not clearly supporting either of the models proposed to explain the evolution of the canaries

the contribution of landslides to landscape evolution in europe abstract after a review of some analytical and conceptual models of slope evolution with the intervention of mass movements a proposal is made of a series of indicators for the quantitative description of landscape evolution in relation to mass movements the ratio between landslide mobilisation rate and downwearing rate is proposed as a quantitative measure of the significance of mass movements in landscape evolution a subdivision of european regions with respect to their susceptibility to landsliding as a process of landscape evolution is proposed the role of landsliding for the evolution of landscape in some regions is described the data presented show that landsliding may in some cases be the main contributor to landscape change

caldera formation at volcan colima mexico by a large large holocene volcanic debris avalanche abstract about 4 300 years ago 10 km 3 of the upper cone of ancestral volcan colima collapsed to the southwest leaving a horseshoe shaped caldera 4 km in diameter the collapse produced a massive volcanic debris avalanche deposit covering over 1550 km 2 on the southern flanks of the volcano and extending at least 70 km from the former summit the avalanche followed a steep topographic gradient unobstructed by barriers resulting in an unusually high area volume ratio for the colima deposit the apparent coefficient of friction fall height distance traveled for the colima avalanche is 0 06 a low value similar to those of other large volume deposits the debris avalanche deposit contains 40 75 angular volcanic clasts from the ancestral cone a small proportion of vesicular blocks that may be juvenile and in distal exposures rare carbonate clasts plucked from the underlying surface by the moving avalanche clasts range in size to over 20 m in diameter and are brecciated to different degrees pulverized and surrounded by a rock flour matrix the upper surface of the deposit shows prominent hummocky topography with closed depressions and surface boulders a thick coarse grained compositionally zoned scoria fall layer on the upper northeastern slope of the volcano may have erupted at the time of collapse a fine grained surge layer is present beneath the avalanche deposit at one locality apparently representing an initial blast event most of the missing volume of the ancestral volcano has since been restored at an average rate of 0 002 km 3 yr through repeated eruptions from the post caldera cone as a result the southern slope of volcan colima may again be susceptible to collapse over 200 000 people are now living on primary or secondary deposits of the debris avalanche and a repetition of this event would constitute a volcanic disaster of great magnitude ancestral volcan colima grew on the southern trenchward flank of the earlier and larger volcano nevado de colima trenchward collapse was favored by the buttressing effect of nevado the rapid elevation drop to the south and the intrusion of magma into the southern flank of the ancestral volcano other such trenchward younging paired volcanoes are known from mexico guatemala el salvador chile and japan the trenchward slopes of the younger cones are common sites for cone collapse to form avalanche deposits as occurred at colima and popocatepetl in mexico and at san pedro volcano in chile

k ar chronology of the volcanic eruptions in the canarian archipelago island of la gomera a geochronological study of the island of la gomera canaries has been carried out by the k ar method the 26 new ages obtained together with the 17 previous determinations show that above the main unconformity of the island separating the basal complex from the later volcanic series there is a unit of lower old basalts more than 10 m y old polymictic volcanic breccias were emplaced between 10 and 9 m y ago the upper old basalts above them were formed between 9 and 6 m y ago with a peak of activity around 7 m y after a period of erosion 6 5 m y a thick series of young basalts associated with trachytic and phonolitic domes and flows were rapidly emplaced between 4 5 4 m y ago finally local basaltic activity took place 2 8 m y ago the age of the basal complex is not well known although three ages 14 6 15 5 and 19 3 m y have been obtained for some alkaline intrusives which seem to represent the youngest events in the complex

landslides in the central coalfield cantabrian mountains nw spain geomorphological features conditioning factors and methodological implications in susceptibility assessment abstract a geomorphological study focussing on slope instability and landslide susceptibility modelling was performed on a 278 km2 area in the nalon river basin central coalfield nw spain the methodology of the study includes 1 geomorphological mapping at both 1 5000 and 1 25 000 scales based on air photo interpretation and field work 2 digital terrain model dtm creation and overlay of geomorphological and dtm layers in a geographical information system gis and 3 statistical treatment of variables using spss and development of a logistic regression model a total of 603 mass movements including earth flow and debris flow were inventoried and were classified into two groups according to their size this study focuses on the first group with small mass movements 100 to 101 m in size which often cause damage to infrastructures and even victims the detected conditioning factors of these landslides are lithology soils and colluviums vegetation pasture and topography dtm analyses show that high instabilities are linked to slopes with ne and sw orientations curvature values between 6 and 0 7 and slope values from 16 to 30 bedrock lithology carboniferous sandstone and siltstone presence of quaternary soils and sediments vegetation and the topographical factors were used to develop a landslide susceptibility model using the logistic regression method application of zoom method allows us to accurately detect small mass movements using a 5 m grid cell data even if geomorphological mapping is done at a 1 25 000 scale

analysis of the deep seated gravitational slope deformations over mt frascare central italy with geomorphological assessment and dinsar approaches abstract a quantitative and innovative dgsd deep gravitational slope deformation assessment method that used integrated remote sensing was tested in the central apennine mountain range italy the movement rate was calculated for selected test areas using the differential sar interferometry small baseline subset sbas technique the selected test areas were previously identified by interpreting both aerial photos and using 32 ers radar images taken between 1993 and 2000 more than 15 cm of cumulative surface displacement occurred across the podalla dgsd along the satellite line of sight los moreover the displacement time series showed non linear deformation rates which included periods of accelerated movement correlated with strong rainfall the high estimated podalla dgsd activity indicates that this type of study should be conducted to monitor the evolution of this phenomenon in addition the dinsar movement rate can be used to improve mapping and identify dgsds in specific landscapes

a methodological approach for the analysis of the temporal occurrence and triggering factors of landslides the temporal occurrence of landslides in an area of the cantabrian range during the last 120 000 years is analyzed an initial relative chronology was established on the basis of aging degree and spatial relationships between landslides and glacial and fluvial features ten landslide classes were thus identified and their chronological limits defined on the basis of 19 14c age determinations on fluvial and glacial deposits including eight new ones the chronology was tested with 14c dates obtained on landslide deposits 10 from previous work and nine new ones the chronological classes identified were compared with existing climate models for the region the type and spatial distribution of landslides in each class were also analyzed the approach made it possible to identify periods during which landslides were triggered mainly by channel incision seismic activity and rainfall increase human activity played a significant role after 5000 bp and especially in the last few centuries mobilization of materials by slope movements has increased in the region by a factor of 10 compared to pre neolithic rates

use of a total station to monitor post failure sediment yields in landslide sites of the shihmen reservoir watershed taiwan abstract landslides have both immediate and extended duration effects on sediment discharge examining the role of post failure soil loss sediment yield of landslides is essential for basin management purposes the comprehensive measurement of sediment production of existing landslides could provide a better understanding in this aspect this study investigated the post failure sediment yield of 13 landslide sites in the shihmen reservoir watershed taiwan during the rainy seasons of 2006 and 2007 using a total station our study showed that soil loss is mainly controlled by rainfall conditions and the geometric and geographic characteristics of each landslide can significantly influence the efficiency of sediment delivery we also observed that rainfall is important in determining landslide retrogression enlargement although vegetation in the landslide area increases with time we obtained a large amount of landslide measurement data which could be useful for future landslide modeling we suggest two regression models for estimating gross soil loss using cumulative rainfall the estimated gross soil loss values of 0 78 to 1 06 m yr 1 are equivalent to 18 096 to 24 592 t ha 1 yr 1 using these estimates we assessed the sources of sediment in the watershed and found that the ratio of landslide erosion soil loss after landsliding and soil erosion from other parts of the watershed was approximately 66 31 3 this study implies that remedying existing landslides is more effective than any other solution in reducing sediment production in the watershed

constructive and destructive episodes in the building of a young oceanic island la palma canary islands and genesis of the caldera de taburiente the results of new field observations 23 new k ar determinations and sixteen previously published determinations provide the basis for the reconstruction of the subaerial volcanic history of the island of la palma after the seamount activity represented by the materials of the basal complex an eruptive phase between 2 0 and 1 3 ma formed a large shield a period of volcanic quiescence followed until around 1 ma during which a large lateral collapse partly destroyed the former edifice between 1 05 and 0 7 ma activity was renewed in the shield and a n s ridge was built in the southern part of the island around 0 7 ma two new large lateral collapses affected the western part of both edifices and they were followed by eruptions between 0 71 and 0 65 ma which built a new edifice that partly filled the depressions thus created the caldera de taburiente constitutes the eroded remnants of the depression formed in the northern shield from 0 65 ma to present activity has been restricted to the n s ridge which has continued to grow southwards there was a general n s migration of volcanic activity with time but in the shield the trend was northwest to southeast eruptive rates seem to have been fairly constant during the different eruptive phases considered between 0 15 and 0 37 km3 ka a very similar succession of constructive and destructive episodes has been obtained for the neighboring island of hierro but in this case the activity started around 0 8 ma and eruptive rates were about 0 5 km3 ka

large scale landslides triggered by quaternary tectonics in the acambay graben mexico detailed analysis was conducted on large scale gravitational tectonic deformations and landslides in the acambay graben an intra arc basin in the trans mexican volcanic belt tmvb field mapping and remote sensing revealed the slope instability of the northern graben boundary induced by the acambay tixmadeje fault two major landslides of 0 1 km3 and 0 05 km3 in volume were identified and their characteristics were analyzed according to the role of tectonics mechanism of slope failure and possible triggering factors quaternary faulting played a major role in increasing the local relief and the activity of the acambay tixmadeje fault represents the main geomorphic factor conditioning the gravitational movements moreover displacements along this fault generated sliding surfaces and reduced the strength of the rock mass the two landslides are classified as large scale rotational slides involving volcanic rocks of late miocene pleistocene age since the acambay graben is a seismogenic area with a known maximum horizontal ground acceleration of 0 5 g a strong earthquake could be ascribed as the possible triggering mechanism of the landslides our work represents the first analysis of large gravitational slope movements in tectonically active regions in mexico a process that can be common in the intra arc basins of the tmvb where active tectonic seismicity weak altered volcanic rocks and heavy rains affect the slope stability copyright 2010 john wiley sons ltd

landslide locations and drainage network development a case study of hong kong abstract landslides are one of the most dominant geomorphic processes that affect humid tropical environments previous studies in hong kong were mainly focused on spatial and temporal relationships between landslide distribution and the potential controlling factors using geographical information systems gis few natural landslide studies have examined the geomorphological aspects regarding the drainage network development at a basin scale this research examined landslide locations with reference to theories of fluvial drainage development eight small drainage basins 5 31 km2 were studied in which 451 landslides were recorded results have shown that landslide locations are related to a headward progression of the drainage network integration starting from the mainstream the fifth order up to the first order tributaries indicated by the systematic variation between morphometric parameters and landslide density

using red mud bauxite for the neutralization of acid mine tailings a column leaching test acid mine drainage amd is an environmental problem produced when sulphides come in contact with an oxidant bacteria and water producing acid generation and metals leaching one solution proposed is to use red mud bauxite rmb which is very alkaline to neutralize oxidized acidic tailings a column leaching test has been set up to evaluate major aspects of field constraints first a field investigation was conducted in which rmb was spread in aggregates before mixing with tailings this setup has been reproduced in the laboratory and compared with a homogeneous mixture the analyses of the water effluent do not show any important difference between the two mixtures second some studies show that the addition of cl brine to rmb helps to maintain the long term neutralization potential brine addition increased the concentrations of ca mg na k and cu in drainage water columns were set up with 10 and 20 rmb to evaluate the effect of the quantity applied addition of greater than 20 rmb incre

quantifying the morphology of flow patterns in landslide affected and unaffected soils summary in mountainous regions landslides are a common natural phenomenon they are often triggered by a combination of steep relief and long lasting rainfalls therefore hydrological conditions in the soil are crucial for their initiation because direct measurements of water flow are difficult and model predictions uncertain we used a dye to visualise flow patterns directly we combined dye tracer experiments with field observations root density and rock fragment content and measurements of soil properties bulk density soil water retention curve and saturated hydraulic conductivity we quantified the morphology of flow patterns by image indices and mutual information that measures the overall dependency between variables and compared two shallow landslides of different ages with a landslide unaffected hillslope our results showed that flow patterns on the landslides were more fragmented and contained larger stained objects than on the landslide unaffected site we relate these findings to a larger stone content and a stronger macropore soil matrix interaction moreover we detected a fissure network on the younger landslide that probably affects its hydrological behaviour field observations soil hydraulic properties and dye tracer studies describe different hydrological aspects of the studied sites and complement the information provided by the morphological image indices

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

quaternary mass movements controlled by a structurally complex setting in the central apennines italy abstract the paper discusses the results of an engineering geology study of an area in central italy affected by complex gravity induced slope instability a finite difference analysis was implemented to demonstrate that stratigraphy and recent tectonics have had a crucial impact on the gravitational processes that have occurred in a built up area of the central apennines italy the creation of a reliable geological evolutionary model proved to be a key tool for subsequent development of a numerical model capable of elucidating the main factors and parameters controlling slope instabilities the study area in the vicinity of the small mountain village of micigliano central apennines displays extensive outcrops of carbonate platform lithotypes hemipelagic marly clayey deposits and arenaceous pelitic turbidites its tectonic setting is very complex with intense faulting thrusts normal faults and complex kinematic faults and folding a geological evolutionary model of the instability processes in the various sectors of the study area was formulated and fine tuned on the basis of detailed geological and engineering geology surveys assumptions on the mechanical and hydraulic characters of the local geological bodies and observation of the morpho evolutionary processes subsequently a stress strain analysis was applied to the model using the finite difference method in order to reconstruct the complex mechanisms governing evolution of the various sectors of the investigated slopes and the effects of gravity caused instability on the exposed lithotypes the numerical model also helped to validate the consistency of the stress strain assumptions with the deformation mechanisms observed in the various investigated sectors of the study area yielding a kinematic picture of the causal factors of the local gravity caused instability in space and time

deformation mechanisms and evolution of a pile reinforced landslide under long term reservoir operation abstract stabilizing piles are widely used for reinforcing landslides in the three gorges reservoir area china due to reservoir operations long term water level fluctuations wlfs may cause instability or failure of the reservoir landslide and piles system rlps this study experimentally investigated the deformation characteristics and mechanisms of the rlps under long term wlfs the results showed that long term wlfs led to loading and unloading cycles and consequently a weakening of the slope stability where retrogressive failure and system instability were observed retrogressive failure at the slope toe was caused by topographical variation and physical and mechanical deterioration which may be a result of the long term wlfs system instability was accompanied by a stress release process above the new slip surface and was determined to be dependent on the geological structure of the rlps based on this investigation the evolution model of the pile reinforced landslide under long term wlfs was proposed even though the rlps was adversely affected by the long term wlfs it maintained a relatively steady state due to the reinforcement of the piles effective pile installation changed the development of the reservoir landslides and prevented the entire slip surface from reaching a critical state thus a catastrophic consequence was avoided except for the local failure through physical modeling this study experimentally provided a deeper understanding of the deformation mechanisms and evolution of the rlps influenced by the long term wlfs

long term neutralisation potential of red mud bauxite with brine amendment for the neutralisation of acidic mine tailings abstract acid mine drainage is an environmental problem produced when sulphide in mine tailings dams comes in contact with o 2 bacteria and water oxidation occurs and a succession of reactions is responsible for producing acid and metals in the environment one solution proposed is to use red mud bauxite rmb that is very alkaline to neutralise acidic tailings previous experiments showed that rmb has a good neutralisation capacity for a short time but the long term neutralisation potential is uncertain so brine was added to rmb to verify if it can improve long term alkalinity retention of rmb some authors have presented results where seawater or other natural or artificial ca and mg rich brines were used with rmb to convert the basicity mainly naoh and other soluble alkalinity into low solubility hydroxide carbonate and hydroxycarbonate minerals results showed that neutral ph conditions were maintained over the entire test for rmb and a mixture of rmb with brine addition of brine to rmb slightly lowered the ph compared to rmb alone rmb alone lost a lot of dissolved alkalinity at the beginning of the test most of the alkalinity was lost in water after a few flushes for rmb samples the addition of brine helped to keep neutralisation potential over more cycles of leaching

the primitive volcano of mount pelee its construction and partial destruction by flank collapse abstract the geology of mount pelee the active volcano of martinique lesser antilles has been actively studied during the past decade this paper reviews the current knowledge about the oldest least well known part of the volcano here called paleo pelee and the relations between paleo pelee and the mont conil volcanic complex paleo pelee consists mostly of volcanic breccias with a few lava flows it differs in this respect from neighbouring active volcanoes such as the grande decouverte soufriere in guadeloupe and the soufriere in st vincent the oldest products of which are mainly lava flows paleo pelee initially formed a regular cone which was comparable in size with the present edifice it is now largely eroded and its products form prominent radial ridges on the western flank of mount pelee these are buried under younger deposits on the eastern flank the uniformly andesitic breccias of paleo pelee are for the most part brecciated lava flows it is inferred that the activity of mount pelee was less explosive at this stage than during following periods neo pelee the paleo pelee formations overlap those of mont conil the geology of mont conil is poorly known however its lowest exposed products are submarine andesitic breccias cut by many dikes this contrasts with paleo pelee where all breccias are of subaerial origin pleistocene limestones are interbedded within the mont conil breccias between 120 and 150 m above sea level though mont conil seems to be closely linked to mount pelee on the basis of available petrological data a major uplift must have occurred sometime during or after the construction of mont conil and forms a recognizable geological boundary between the two volcanic systems the paleo pelee edifice was partially destroyed by a flank collapse event that occurred on the southwest flank during the early stage 40 000 20 000 y b p of neo pelee this event is evidenced by a large 6 2 5 km horseshoe shaped structure which is limited by well preserved morphological scarps on land and by a 300 m offshore scarp as shown by seabeam bathymetry paleo pelee breccias and lava flows are truncated by the boundary of the collapse structure lava domes occupied the upslope part of the structure at a later time these domes are intersected by the present crater etang sec which has probably been the active vent for at least 2000 years the active crater is located at the intersection between the flank failure depression and an older caldera formed at the paleo pelee stage but probably enlarged later the flank failure structure appears as a major structure of the volcano and creates a strong structural asymmetry in the edifice this fact should be considered when dealing with such various aspects as the hydrogeology of the volcano the structural control of past and future eruptions and the volcanic hazards

human impact on geomorphic processes and hazards in mountain areas in northern spain abstract the temporal occurrence of slope movements their contribution to relief evolution and human influence on those processes in two study areas of northern spain are presented the work is based on temporal analyses covering 100 ka in one study area and 43 years in the other temporal analysis has been the basis for quantitatively assessing the magnitude of human influence and developing landslide susceptibility and hazard models with known independently tested prediction capability the results obtained in one study area show a relationship between landsliding periods and increasing precipitation during upper pleistocene and holocene significant increases of landslide frequency and mobilisation rate were also found around 5500 and 200 years ago those moments coincide with two periods of intensified human presence and activities neolithic and industrial revolutions the increase observed represents about one order of magnitude from pre neolithic to present a similar increase has been found between 1954 and 1997 in the other study area the latter increase shows no relationship with changes in climate parameters or seismic activity a fairly good correlation has been found between landslide frequency and socioeconomic indicators of human activity sedimentation rates in two neighbouring estuaries were determined and significant increases particularly in the second part of last century were also found evidence obtained suggest that the increases observed in the frequency of slope instability events and therefore hazard denudation and sedimentation rates are due to a greater extent to indirect geomorphologic changes caused by human action rather than climate change detailed analysis of landslide frequency during that 43 year period has also been used to produce and validate landslide susceptibility models and obtain landslide hazard maps with known prediction accuracy validation tests were carried out comparing susceptibility maps based on landslides that have occurred in the past with the ones occurring in several later periods prediction capability of models could thus be determined validation of susceptibility maps using data derived from the temporal analysis of landslides was used to obtain hazard maps expressed as probability of new ruptures in a given time period on the basis of past trends in terrain behaviour possible impacts of a growing influence of human activities on the terrain have been incorporated into the assessment of future hazards by considering different scenarios

insights on the kinematics of deep seated gravitational slope deformations along the 1915 avezzano earthquake fault central italy from time series dinsar abstract among the causes of deep seated gravitational slope deformations dgsd the most important is relief energy which is closely related to the intensity of the active tectonic deformations either at the regional scale or at the scale of a single active fault we analyzed some examples of dgsd from the eastern border of the fucino basin in the central apennines where extensional tectonics has been active since the late pliocene photogeological and field geomorphological analysis was performed to identify landforms typically associated with dgsd such as counterslope scarps double crests trenches and bulging slopes these features are located on a mountain range at less than 1 km from the causative fault of the 1915 avezzano earthquake we used the sbas differential sar interferometry technique to measure the slow movements of the surface and calculated differential vertical and horizontal ground velocities of 2 4 mm yr 1 during the period spanning from 1992 to 2001 the quantitative information on the kinematics of the deformation provided some inferences on the different processes responsible for the evolution of the observed dgsd the displacement time series shows non linear deformation trends at some locations possibly correlated with a strong meteorological event we speculate that dgsd in this area are normally subject to slow deformation and that sudden slip along sliding surfaces observed in excavations may sporadically be triggered off by extreme meteorological or seismic events evidence of catastrophic collapse of previous dgsd along the same mountain slope reinforce this hypothesis

chronological constraints on a holocene landslide in an intermontane basin of the southern apennines italy morphological evolution and palaeoclimate implications in this work a detailed geomorphological study aimed to reconstruct the holocene evolution of a slope largely affected by landsliding is presented the study area is located in the lower valley of the tanagro river flowing in the auletta basin a pliocene to quaternary tectonic depression located along the elongation axis of southern apennines in order to investigate the relationships between landscape evolution and triggering factors and to better constrain the holocene palaeoclimate scenario in which the mass movements occurred geomorphological data have been integrated with those deriving by the stratigraphic chronological and minero geochemical analyses of the deposits genetically related to the landslide events the investigated landslide shows a complex style of activity with compound rotational and translational slide in the upper part of the slope evolving into flow in the lower part the chronological evolution of the landslide activity has been constrained through radiocarbon dating of pa

multiple seepage faces on layered slopes and their implications for slope stability analysis this study provides an analysis of the water table configuration and pore pressure distribution in layered hillsides a finite element model was used to simulate two dimensional saturated unsaturated steady state flow through layered slopes a laboratory sand tank experiment was used to verify the physical foundation of the mathematical model it is shown that layered slopes feature multiple seepage faces perched water tables and wedge shaped unsaturated zones the pore pressure distribution and the distribution of multiple seepage faces are strongly dependent on the position of the impeding layers and their hydraulic properties predictions of pore pressure fields based on homogeneous saturated analyses may be significantly in error when applied to problems on layered slopes slope stability analyses on layered slopes that do not take into account the presence of unsaturated wedges beneath the impeding layers can lead to overdesign of the stable slope angle key words groundwater conditions unsatu

the transition zone of the canary current upwelling region abstract like all the major upwelling regions the canary current is characterised by intense mesoscale structure in the transition zone between the cool nutrient rich waters of the coastal upwelling regime and the warmer oligotrophic waters of the open ocean the canary island archipelago which straddles the transition introduces a second source of variability by perturbing the general southwestward flow of both ocean currents and trade winds the combined effects of the flow disturbance and the eddying and meandering of the boundary between upwelled and oceanic waters produce a complex pattern of regional variability on the basis of historical data and a series of interdisciplinary field studies the principal features of the region are described these include a prominent upwelling filament originating near 28 n off the african coast cyclonic and anti cyclonic eddies downstream of the archipelago and warm wake regions protected from the trade winds by the high volcanic peaks of the islands the filament is shown to be a recurrent feature apparently arising from the interaction of a topographically trapped cyclonic eddy with the outer edge of the coastal upwelling zone its role in the transport and exchange of biogenic material including fish larvae is considered strong cyclonic eddies observed throughout the year drift slowly southwestward from gran canaria one sampled in late summer was characterised by large vertical isopycnal displacements apparent surface divergence and strong upwelling producing a fourfold increase in chlorophyll concentrations over background values such intense eddies can be responsible for a major contribution to the vertical flux of nitrogen the lee region of gran canaria is shown to be a location of strong pycnocline deformation resulting from ekman pumping on the wind shear boundaries which may contribute to the eddy formation process

magnitude of the sediment transport event due to the late pleistocene sector collapse of asama volcano central japan abstract a rapid large scale sediment transport event due to a catastrophic landslide plays an important role in changing drainage basin topography however volumetric evaluation of such events that occurred before the holocene has been limited this study quantitatively examines the volume of sediments derived from the late pleistocene 24 ka sector collapse of asama volcano central japan a sequence of sediments supplied from the sector collapse was identified based on geological and geomorphological field surveys and literature search the total volume of the sediments was estimated from borehole columns to be 4 9 5 4 km3 reconstruction of the morphology of the volcanic edifice before and after the collapse provided an estimated volume of the lost sector of 4 0 km3 the greater estimated volume of the sediments released by the collapse is attributed to the entrainment of fluvial material during the flow of volcanic debris and to dilation of the original volcanic material

controls on the stability and inclinations of hillslopes formed on hard rock in identifying controls on rock slope form a distinction is made between 1 rock slopes with joints which dip steeply out of a cliff and hence are subject to mass failure of the rock mass above a critical joint and 2 rock slopes with inclinations which are either in equilibrium with the mass strength of their rocks or have profiles which will develop towards strength equilibrium as cross joints open in the first class of slope stability results not just from the basic frictional resistance of the rock but also from the frictional roughness along the critical joint and from the normal stress acting across that joint stability may be reduced by weathering and loss of strength of the joint wall rock as a result of normal stress variations with depth induced by overburdens high cliffs which are not undercut have a concave profile the second group of slopes includes those with inclinations controlled at the scale of individual joint blocks buttressed slopes and those on unjointed rock masses buttressed and unjointed rock masses develop towards a condition of mass strength equilibrium as cross joints open strength equilibrium slopes may be recognized by application of a rock mass strength classification proposed for geomorphic purposes eleven propositions are formulated which identify controls on rock slope development and some consequences of these controls

quantifying and modeling post failure sediment yields from laboratory scale soil erosion and shallow landslide experiments with silty loess rainfall events on steep hillslopes can cause both soil erosion and shallow landslides these processes interact with each other and need to be studied in an integrated way to understand hillslope sediment yields the main aim of this research is to study post failure sediment yield following landslides that alter local slope gradients a laboratory flume under a rainfall simulator was used to quantify erosion and shallow landslides in fine grained silty loess soils the flume was divided into an upper and a lower section the slopes of which could be altered a total of 12 experiments were conducted on slopes ranging from 35 to 47 in the upper and 5 to 10 in the lower flume sections shallow landslides were triggered in four of the 12 experiments sediment and runoff were collected from the flume outlet every minute during landslides and every 10 min before and after landslides changes in the soil slope after landslides occurred were recorded results showed that peak sediment yields were related to landslide occurrence and proximity to the outlet post failure reduction in sediment yields was related to the evolution of the hillslope after slope failures a simple rule based soil redistribution model of runout distance was validated using the experimental results the water erosion prediction project wepp model was used to simulate runoff and soil erosion during pre and post failure rainfall events predicted runoff rates and sediment yields using wepp were in good agreement with those measured in both pre and post failure events indicating that the model can be used successfully as part of an integrated approach to modeling sediment yields in landslide prone landscapes

impact of mass movements on geo and biodiversity in the polish outer flysch carpathians complex research was simultaneously done on the geological geomorphological and biocenotic features of landslide areas in the polish outer flysch carpathians the research allowed us to define the relations between the diversity of the landslide originating landforms and the biotopes occurring within them high geodiversity diversity of landforms soil and water of landslide areas allows for a mosaic network of extremely diversified natural habitats all of these natural habitats together are characterized by a specific biodiversity dependence between geo and biodiversity in landslide areas is connected with a specific co evolution which is related to the adaptation of the ecosystems to landforms comprehensive research of this relation to landslide areas would promote the necessity to protect the landslide areas unfortunately such research done in the carpathians is still sporadic the comprehensively documented landslide areas are especially valuable elements of the nature protection network within the carpathian euro region if made reasonably accessible they may be used for didactic purposes and in geotourism

linking benthic community structure to terrestrial runoff and upwelling in the coral reefs of northeastern hainan island abstract near shore coral reefs in northeastern hainan island are close to river mouths and aquaculture ponds and also located at the center of the qiongdong upwelling qdu however it is still unclear how terrestrial runoff and upwelling influence the community composition and spatial distribution of the benthos during three cruises in 2010 and 2011 in wenchang northeastern hainan island we determined a subset of environmental parameters in seawater e g temperature salinity do dissolved inorganic nutrient din turbidity and transparency and macroalgal 15 n and investigated the benthic communities e g live coral cover coral species richness juvenile coral density macroalgal cover and coverage of calcified algae by video transect and visual census techniques at 10 stations i e 1s 6d the results showed that the qdu has influenced the reef waters in wenchang in 2011 the upwelling started in early may peaked in july and disappeared in september and most upwelling events lasted for 1 2 weeks between may and july the results also demonstrated that the reef water was nutrient enriched stations close to the river mouth and aquaculture ponds had higher levels of din and a higher percentage of ammonia in din and there was consistently lower live coral cover juvenile coral density and higher macroalgal cover at some stations in this study live coral cover was negatively correlated with macroalgal cover i e 2s 6d live coral cover species richness and juvenile coral density all increased with the distance away from the river outlet and decreased with the rise of din these results suggest that terrestrial runoff and upwelling stimulate nutrient enrichment and that overgrowing macroalgae has an important influence on the coral communities in northeastern hainan island

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

influence of landslides on biophysical diversity a perspective from british columbia landslides have long been overlooked or underestimated as important natural disturbance agents in particular the ecological role of landslides in maintaining biological diversity has been largely ignored here we provide a western canadian british columbian perspective on the influences of landslides on biophysical diversity which is related in several ways to biological diversity we recognize several types of biophysical ecological diversity site diversity soil diversity and the derivative habitat or ecosystem including aquatic ecosystems diversity there are also a variety of landslide types depending on materials and on the rate and style of movement we discuss the roles of different landslide types on various aspects of terrestrial diversity landslides are simultaneously depositional and erosional processes that influence sites by redistributing materials and changing surface expression usually creating a complex microtopography that can include very dry ridges and hummocks and sometimes depressions with standing water landslide impacts to site also influence soil and soil development portions of landslides with exposed parent material are set back to the initial stages of soil development and ecological succession landslides can also change soil density structure porosity surface texture chemistry and microclimate by changing site and soil landslides also influence habitat landslides influence habitat diversity by engendering a mosaic of seral stages often both primary and secondary and in overwhelmingly forested landscapes often create nodes or hotspots of non forested habitat and biota in some areas like the boreal forest there is an important interplay between landslides and fire while on the coast of british columbia debris and snow avalanches can be the dominant disturbance agent low gradient and deep seated landslides are often opportunistically colonized by beaver and other water and shrub loving fauna sag ponds and impounded streams provide aquatic habitat often with standing dead trees landslide rubble and scarps provide denning nesting habitat escape terrain and cliff habitat for vertebrates

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

geotechnical aspects of soil slips in alpine regions abstract slope movements are due to many different causes numerous investigations carried out during the last ten years have led to the supposition that almost all slope movements and particularly those occurring in soils are conditioned by a significant combination of factors for the alpine regions quantity duration and kind of precipitation have to be considered as direct mechanical causes combined with such contributing factors as geological and soil mechanical properties aspect vegetation slope inclination and slope morphology they will determine the type dimensions and process of slope movements the detailed investigation of 140 slope movements in slightly cohesive soils show that the process of movement is represented by sliding and flow events in particular it was found out that shallow scars with planar slides predominate so that the supposition of an infinite slope model for slope stability appears to be justified in many cases debris flows and debris avalanches continued downslope of the source area of the scars

characterization of debris avalanche deposits in japan abstract seventy one debris avalanche deposits are identified from 52 japanese quaternary volcanoes the structures of these volcanoes are mostly stratovolcanoes and lava domes no avalanche deposit is found in calderas pyroclastic cones or maar volcanoes debris avalanche deposits are found in 18 of all quaternary volcanoes or 25 of quaternary stratovolcanoes and lava domes the ratio rises to 49 when considering only active stratovolcanoes and lava domes at least five debris avalanche deposits have formed since 9th century the maximum height difference of sliding h for each debris avalanche ranges from 200 to 2400 meters and the maximum runout distance of sliding l ranges from 1 6 to 32 km the ratio h l ranges from 0 2 to 0 06 and becomes smaller in larger debris avalanches they are more mobile than landslides in non volcanic areas volume is within a range of 0 03 and 9 km 3 there is no relation between the direction of sliding and the regional horizontal compressional stress axis at the site of a volcano two dimensional computer simulations of avalanches using a simplified physical model are made the maximum velocity is mainly controlled by the length of steep slope

large landslides induced by fluvial incision in the cenozoic duero basin spain abstract the pleistocene opening of the endorheic duero river drainage basin northwestern spain and central portugal has led to river incision creation of steep valley sides and development of large 0 1 km2 and episodically active rotational and roto translational landslides along river reaches where a weak geological lithology has been exposed by river erosion these landslides occur in the central part of the duero basin despite low precipitation weak contemporary seismicity and low regional relief these landslides occurred as a result of the downcutting of the duero river and its tributaries through a sequence of miocene basin fill sediments in the last few thousand years the incision reached a series of high plasticity low strength clay layers within the sedimentary sequence owing to this mechanism these landslides occurred in a specific area at a specific period of time all of the large landslides are located at the outside of meander bends suggesting that river lateral erosion facilitated slip failures recent anthropogenic activities to control river flows and to stabilize river banks have decreased the possibility of future landslides in this area