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

extensive deformations of rock slopes in southern coast mountains southwest british columbia canada extensive deformations of mountain slopes occur in crystalline intrusive rocks in the southern coast mountains of british columbia typical morphological evidence of slope movement includes extensive systems of tension cracks grabens and antislope scarps collectively referred to here as linears these landforms involve displacements along penetrative joints observed in surface exposures kinematic tests on rock structural data indicate that the observed patterns of linears are generally consistent with the feasible gravitational movements along the dominant discontinuities most sites indicate sliding as the most likely initial mode of movement followed by or accompanied by toppling and toppling induced sliding movements and do not support the view that linears are the traces of active faults

onset and timing of deep seated gravitational slope deformations in the eastern alps italy abstract a previously unrecognised complex of deep seated gravitational slope deformations dsgsd extends 20 km along upper venosta valley in the eastern alps italy mt watles exhibits spectacular features indicative of dsgsds including double ridges trenches and counterscarps the slope deformation occurs along a nappe boundary now corresponding to the schlinig normal fault is also conditioned by recent faults marked by shallow earthquakes and shows glacial paraglacial controls on slope evolution the mt watles dsgsd is a complex deep seated compound slide along a basal shear zone involving the schlinig fault gravitational reactivation of ne trending fractures formed gravitational scarps counterscarps and half grabens in the upper slope whereas the lower part of the slope partially collapsed although our work indicates the importance of the schlinig fault and recent fracturing on slope failure the trigger seems to be postglacial debuttressing of the valley walls radiocarbon dating of peat deposits within one of the major counterscarps indicates that slope deformation started during the lateglacial period and continued during the holocene in several slope sectors

developments in the characterization of complex rock slope deformation and failure using numerical modelling techniques recent advances in the characterization of complex rock slope deformation and failure using numerical techniques have demonstrated significant potential for furthering our understanding of both the mechanisms processes involved and the associated risk this paper illustrates how rock slope analyses may be undertaken using three levels of sophistication level i analyses include the conventional application of kinematic and limit equilibrium techniques with modifications to include probabilistic techniques coupling of groundwater simulations and simplistic treatment of intact fracture and plastic yield such analyses are primarily suited to simple translational failures involving release on smooth basal rear and lateral surfaces where the principle active damage mechanisms are progressive failure and or asperity breakdown level ii analyses involve the use of continuum and discontinuum numerical methods in addition to simple translation level ii techniques can be applied to complex translational rock slope deformations where step path failure necessitates degradation and failure of intact rock bridges along basal rear and lateral release surfaces active damage processes in this case comprise not only strength degradation along the release surface e g asperity breakdown but also a significant component of brittle intact rock fracture level iii analyses involve the use of hybrid continuum discontinuum codes with fracture simulation capabilities these codes are applicable to a wide spectrum of rock slope failure modes but are particularly well suited to complex translation rotational instabilities where failure requires internal yielding brittle fracturing and shearing in addition to strength degradation along release surfaces through a series of rock slope analyses the application of varied numerical methods are discussed particular emphasis is given to state of the art developments and potential use of level iii hybrid techniques d 2005 elsevier b v all rights reserved

analysis of massif fracturing during deep seated gravitational slope deformation by physical and numerical modeling abstract both 3 d physical modeling and 2 d numerical modeling were used to analyze the development of deep seated gravitational slope deformations we focused especially on the link between fracturing and morphological features such as sagging sackung physical modeling was performed by using properly scaled analogue materials as well as an original vertical accelerator device this device enables cyclic loading of the model and to advance step by step in the deformation process this technique is thus particularly well suited to analyze rupture initiation and evolution surface deformation is registered with a high resolution digital camera internal model deformation was studied by making cross sections at different experiment stages the failure of one or both mountain sides was observed with a deep seated failure zone that follows an almost circular trajectory it intersects the surface perpendicularly in the upper part other fractures are generated in the moving mass in response to its motion fracture network becomes wider and morphological features such as counterscarps are generated numerical models were performed with a 2 d finite element code named adeli we tried to reproduce physical modeling results by using the same mechanical behaviour and parameters of the analogue material the results reproduced failure initiation well but poorly described moving mass deformation furthermore rupture initiation in the 2 d numerical models occurs more easily e g for a lower acceleration value than in the 3 d physical models confirming the importance of the three dimensional analysis

a procedure for landslide susceptibility zonation by the conditional analysis method numerous methods have been proposed for landslide probability zonation of the landscape by means of a geographic information system gis among the multivariate methods i e those methods which simultaneously take into account all the factors contributing to instability the conditional analysis method applied to a subdivision of the territory into unique condition units is particularly straightforward from a conceptual point of view and particularly suited to the use of a gis in fact working on the principle that future landslides are more likely to occur under those conditions which led to past instability landslide susceptibility is defined by computing the landslide density in correspondence with different combinations of instability factors the conceptual simplicity of this method however does not necessarily imply that it is simple to implement especially as it requires rather complex operations and a high number of gis commands moreover there is the possibility that in order to achieve satisfactory results the procedure has to be repeated a few times changing the factors or modifying the class subdivision to solve this problem we created a shell program which by combining the shell commands the gis geographical research analysis support system grass commands and the gawk language commands carries out the whole procedure automatically this makes the construction of a landslide susceptibility map easy and fast for large areas too and even when a high spatial resolution is adopted as shown by application of the procedure to the parma river basin in the italian northern apennines

a deep seated compound rotational rock slide and rock spread in se spain structural control and dinsar monitoring abstract the northern slope of the sierra de aitana eastern betic cordillera is characterized by a long mountain front with a prominent eocene limestone scarp overlying ductile eocene marlstones this stratigraphic feature and the highly stepped topography produced by several normal faults favor gravitational processes such as rock avalanches rock slides and rock falls this paper reports a compound landslide comprising a rotational rock slide and slab type lateral spreading affecting these materials with blocks of volumes up to 106 m3 this lateral spread process produced singular and spectacular morphological features the simas de partagat which are trenches 20 m wide and up to 40 m deep formed by the widening of discontinuities the use of a differential sar interferometry technique for monitoring this landslide over a time span of 11 yr has revealed that velocity of movement is insignificant with rates comprised between 0 and 2 mm yr 1 and cumulative negligible displacements individual rock blocks initially located at the free face of the scarp were affected by slides at the base of the scarp descending from a few to several dozen meters along the slope blocks broke up as displacement progresses with several in different stages of evolution being recognizable along the slope differential sar interferometry shows a greater activity in the area north of compound landslide although velocity is extremely low below 16 mm yr 1 this extremely slow movement revealed by interferometry is in agreement with other geological and geomorphological evidence such as the existence of speleothems and cemented breccias against the head walls of the trenches both deposits are indicative of a long period of discontinuity widening also undisturbed debris deposits covering ancient rock slides are indicative of very slow gravitational processes characterized by long dormant periods in addition a historical picture from 1898 shows nearly negligible change in the simas de partagat over this 112 yr period

the sant agata feltria landslide marche region central italy a case of recurrent earthflow evolving from a deep seated gravitational slope deformation abstract this paper examines the evolution of a large scale earthflow located in the northern sector of the marche region central italy in this area mass movements of different typology are particularly frequent since geological and geomorphological conditions often favour slope instability among these many mass movements the one affecting the historical village of sant agata feltria has been chosen also because its evolution has been recorded in chronicles starting from ancient times in fact reactivations of the 5 4 km long earthflow crossing the village have been quoted at least 12 times starting from the 16th century even though more ancient activations have been inferred historic researches and geomorphologic analyses allowed the detailed reconstruction of the evolution and the mechanism of the phenomenon outlining its causes and delineating risk zonation in particular a deep seated gravitational movement lateral spreading marked by trenches and ponds has been recognised at the top of the landslide the earthflow has been interpreted as a more surficial side effect of the deep seated phenomenon which constitutes its source area it has also been highlighted that reactivations coincided with long lasting and intense rainfalls whilst no direct connection seems to exist with earthquakes even though the area is seismically rather active and seismic shocks could have been among the major triggering factors for the deep seated deformation the oldest and probably most catastrophic recorded event itself 1561 a d took place during the first stages of a period of severe climate that involved the whole of europe

analysis of landslide inventories for accurate prediction of debris flow source areas abstract for the generation of susceptibility maps on medium scales 1 25 000 to 1 50 000 using statistical techniques a reliable landslide inventory is needed together with factor maps used as inputs this paper compares landslide susceptibility maps obtained with the same methodology but using different landslide inventories the official italian landslide inventory geoiffi for the lombardy region and a recently mapped inventory df2001 the analysis included four main steps i preparation of debris flow inventories using both random and spatial partitions and factor maps as explanatory variables ii calculation of accountability and reliability indices for a preliminary susceptibility analysis and selection of an appropriate combination of the factor maps for detailed analysis iii evaluation and validation of the obtained susceptibility maps and iv comparison of the results and selection of the final map the study area is located in the valtellina valley in the central italian alps the analysis identified highly susceptible areas of shallow landslides that may generate debris flows it was demonstrated that more precisely delimited source areas for landslide induced debris flows produce better susceptibility maps however the improvement of these maps was relatively limited when the inventories were randomly subdivided higher improvements were observed after the subdivision of the inventories into three geographical parts with different geomorphological characteristics although the modelling showed very similar results if evaluation is made using standard techniques the spatial pattern of the susceptibility maps was highly variable and dependent on the combination of the factor maps used

aspects of landslide activity in the mercantour massif and the french riviera southeastern france abstract landslides pose serious hazards in the mercantour massif and the french riviera in southeastern france the context for landslide development is a particularly favourable one both in terms of the geomorphic and structural setting of this alpine region and of the climatic hydrologic and seismic factors that trigger such failures high mountain relief and steep slopes constitute a very favourable setting for failures affecting massive basement rocks and a very heterogeneous sedimentary cover whose resistance has been weakened by weathering tectonic stresses and cambering due to gravity among trigger factors the important appears to be the precipitation regime rainfalls are commonly concentrated into short high intensity downpours or into bursts of sustained falls over periods of several days leading to soil saturation and lubrication of potential failure planes snowmelt also contributes to these lubrication processes earthquakes affecting this region are also a potentially important landslide trigger however while a lot of work has been done on the relationship between extreme climatic events and landslide activity much less is known of the trigger effects of earthquakes both the background factors that promote landslide development and the factors that trigger such failures are discussed within a time frame of landslide development progressive changes in soil strength due to weathering rock cambering and shattering processes lead to long term reduction in resistance superimposed on these progressive changes are episodic triggerings related to rainfall and snowmelt episodes or earthquakes landslides may occur as shallow low volume one time events or may be part of a progressive long term failure the former generally affect unconsolidated or clay rich sedimentary rocks especially on the coastal hillslopes of the french riviera a notable exception of a major voluminous one time event was the submarine landslide of the var delta in 1979 this landslide like numerous other smaller subaerial landslides onland was largely a result of human activities this landslide occurred following extensive modification of the var delta and notably reclamation of the steep fine grained delta front deforestation quarrying urbanisation and road network developments are various ways in which human activity has destabilized the coastal hillslopes favouring the development of numerous shallow landslides following each episode of heavy rainfall progressive landslides on the upper hillslopes of the mercantour massif have developed over long time spans order of 101 to 105 yrs and have involved more complex interactions between lithological controls slope characteristics and trigger factors the collelongue and bois de malbosc landslides have evolved into now stable failures buttressed by resistant migmatitic diorites or amphibolites the more voluminous and well monitored clapiere landslide is a relatively simple rotational landslide of the toe failure type this active landslide poses a serious to inhabitants and infrastructure in the tinee valley the importance of continued field monitoring modelling and mapping of landslides and their hazards is emphasised

landslide susceptibility assessment using weights of evidence applied to a study area at the jurassic escarpment sw germany a gis based model for the assessment of the landslide susceptibility in a selected area of the jurassic escarpment in the swabian alb sw germany is described using the weights of evidence method a quantitative model applied to landslides and their causative factors was created and illustrated in susceptibility maps while previous research work in this area concentrated on large scale investigations the present study was carried out at a regional level with a target scale of 1 150 000 the method is based on the assumption that future landslides will occur under the conditions similar or equal to those of past comparable landslides of the same type therefore the analysis was limited to one single type of landslides where the causative factors can be assumed as stable over a period of time due to uncertainties in the model mainly because of variances of the weights assigned to the causative factors the derived probability values representing the susceptibility for future landslides have to be considered relative however potential susceptible areas can be delineated and landslide indicators can be identified from the available data set slopes with angles from 11 to 26 composed of the oxford limestone marls as well as strongly argillaceous and silty colluvial material such as solifluction layers and colluvial cones are susceptible the main soil type of the escarpment and the other steep slopes of the swabian alb valleys are rendzinas formed in solifluction layers rendzina profiles including rock debris and clay which are superimposed on marl debris were also identified as landslide indicators these findings are in agreement with previous geomorphological studies in the same area the methodology seems to have widespread applicability beyond this local research area with the limitation that the knowledge of past landslides input to the model affects the absolute value of the final probability

landslide hazard evaluation a review of current techniques and their application in a multi scale study central italy in recent years growing population and expansion of settlements and life lines over hazardous areas have largely increased the impact of natural disasters both in industrialized and developing countries third world countries have difficulty meeting the high costs of controlling natural hazards through major engineering works and rational land use planning industrialized societies are increasingly reluctant to invest money in structural measures that can reduce natural risks hence the new issue is to implement warning systems and land utilization regulations aimed at minimizing the loss of lives and property without investing in long term costly projects of ground stabilization government and research institutions worldwide have long attempted to assess landslide hazard and risks and to portray its spatial distribution in maps several different methods for assessing landslide hazard were proposed or implemented the reliability of these maps and the criteria behind these hazard evaluations are ill formalized or poorly documented geomorphological information remains largely descriptive and subjective it is hence somewhat unsuitable to engineers policy makers or developers when planning land resources and mitigating the effects of geological hazards in the umbria and marche regions of central italy attempts at testing the proficiency and limitations of multivariate statistical techniques and of different methodologies for dividing the territory into suitable areas for landslide hazard assessment have been completed or are in progress at various scales these experiments showed that despite the operational and conceptual limitations landslide hazard assessment may indeed constitute a suitable cost effective aid to land use planning within this framework engineering geomorphology may play a renewed role in assessing areas at high landslide hazard and helping mitigate the associated risk

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

mass extinction and recovery of the early toarcian early jurassic brachiopods linked to climate change in northern and central spain abstract the early toarcian mass extinction event represented the most important mesozoic and cenozoic turnover of the population of brachiopods and severely affected other benthic fauna two main hypotheses have been proposed to explain the synchronous and global mass extinction an oceanic anoxic event or a warming episode to test both hypotheses the dynamics of the brachiopod assemblages below and above the extinction boundary are analyzed and compared with the seawater paleotemperature variations calculated from the 18 o data recorded in belemnite rostra five sections from northern and central spain well dated with ammonites have been selected for this study the sections show no indication of sedimentary breaks and contain abundant brachiopods which have been grouped into four assemblages the changes observed in the brachiopod assemblages show a close correlation with the changes in the seawater paleotemperatures the oldest assemblage assemblage 1 coincides with a cooling interval recorded to have taken place in the latest pliensbachian paleobiogeographical reconstruction shows that this assemblage was distributed at paleolatitudes between 30 and 45 n with a preference for relatively cool waters with the rise of temperatures that took place during the earliest toarcian tenuicostatum zone assemblage 1 was substituted by assemblage 2 which composed of different species of the same genera but considerably restricted to the warmer waters of lower paleolatitudes between 28 and 35 n coinciding with the rapid and pronounced increase in seawater temperature recorded at the tenuicostatum serpentinum zonal boundary all of these brachiopod species disappeared in the studied localities marking clearly the extinction boundary predominant southward currents through the laurasian seaway precluded the possible migration of the brachiopods to cooler northern waters the brachiopods disappearance is independent from the oxygenation degree of the sea bottom and therefore the rapid warming seems to be the most plausible cause of the mass extinction after the extinction event the recovery of the brachiopods was uneven subsequent to a brief pause recovery was rapid in central spain and in other southern areas of western tethys whereas in northern spain and in the whole of europe north of the french central massif brachiopods did not recover until the mid to late toarcian times

deep seated failure propagation in a fractured rock slope over 10 000 years the la clapiere slope the south eastern french alps abstract the la clapiere area tinee valley alpes maritimes france is a typical large complex unstable rock slope affected by deep seated gravitational slope deformations dgsd with tension cracks scarps and a 60 106 m3 rock slide at the slope foot that is currently active the slope surface displacements since 10 ka were estimated from 10be ages of slope gravitational features and from morpho structural analyses it appears that tensile cracks with a strike perpendicular to the main orientation of the slope were first triggered by the gravitational reactivation of pre existing tectonic faults in the slope a progressive shearing of the cracks then occurred until the failure of a large rock mass at the foot of the slope by comparing apertures variations and changes in direction between cracks of different ages three phases of slope surface displacement were identified 1 an initial slow slope deformation spreading from the foot to the top characterized by an average displacement rate of 4 mm yr 1 from 10 5 6 ka bp 2 an increase in the average displacement rate from 13 to 30 mm yr 1 from the foot to the middle of the slope until 3 6 ka bp and 3 development of a large failure at the foot of the slope with fast displacement rates exceeding 80 mm yr 1 for the last 50 years the main finding of this study is that such a large fractured slope destabilization had a very slow displacement rate for thousands of years but was followed by a recent acceleration the results obtained agree with several previous studies indicating that in situ monitoring of creep of a fractured rock slope may be useful for predicting the time and place of a rapid failure

tilt signals derived from a geoscope vbb station on the piton de la fournaise volcano we report some very long period transients observed on a very broadband seismic station of the geoscope network which is situated 8 km away from the summit of the piton de la fournaise volcano we transform the ground velocity measured by the seismic station into tilt and test the result by comparing with data from blum type classical pendulum tiltmeters located in the same vault the comparison validates the use of the horizontal seismometers for measuring tilt for periods shorter than 25 hours the method is applied to the transients observed prior to several eruptions and magmatic intrusions since 1991 because of the moderate distance between geoscope station and the summit of the volcano the obtained tilt measurements provide information about eruptions and intrusions which complement the information on the geometry and location of the magmatic source provided by the summit tilt network

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

a gis based automated procedure for landslide susceptibility mapping by the conditional analysis method the baganza valley case study italian northern apennines among the many gis based multivariate statistical methods for landslide susceptibility zonation the so called conditional analysis method holds a special place for its conceptual simplicity in fact in this method landslide susceptibility is simply expressed as landslide density in correspondence with different combinations of instability factor classes to overcome the operational complexity connected to the long tedious and error prone sequence of commands required by the procedure a shell script mainly based on the grass gis was created the script starting from a landslide inventory map and a number of factor maps automatically carries out the whole procedure resulting in the construction of a map with five landslide susceptibility classes a validation procedure allows to assess the reliability of the resulting model while the simple mean deviation of the density values in the factor class combinations helps to evaluate the goodness of landslide density distribution the procedure was applied to a relatively small basin 167 km2 in the italian northern apennines considering three landslide types namely rotational slides flows and complex landslides for a total of 1 137 landslides and five factors namely lithology slope angle and aspect elevation and slope bedding relations the analysis of the resulting 31 different models obtained combining the five factors confirms the role of lithology slope angle and slope bedding relations in influencing slope stability

tertiary extensional tectonics in tuscany northern apennines italy abstract two extensional events have been recognized in the tertiary evolution of tuscany the first event occurred in the period between the late oligocene and late tortonian and caused a stretching of 120 or greater the second event occurred between the late tortonian and quaternary periods and caused a stretching not greater than 10 the first event is characterized by the exhumation of middle crust rocks and therefore by the development of core complexes the most significant structures of the first event are low angle normal faults which characterize the upper plate of the core complexes and ductile shear zones which characterize the lower plate the low angle normal faults tend to die out in the late triassic evaporite level which constitutes the main detachment of the core complexes the main structures of the second extensional event are high angle normal faults which dissect all the previous tectonic features these faults border tectonic depressions which were the site of clastic sedimentation from late tortonian to quaternary time these normal faults may tend to flatten in a seismic lozenge shaped band explained as an active extensional shear zone which is located at the brittle ductile boundary a similar explanation is given for the detachment located in the late triassic evaporite level during the first extensional event while the first extensional event is in the framework of the northern apennine post collisional evolution the second extensional event because it affects an already stretched crust could be attributed to the southern tyrrhenian opening which began during late tortonian

landslide susceptibility mapping for a part of tectonic kelkit valley eastern black sea region of turkey considering damage to man made structures by natural hazards in turkey landslides are the second most important hazard after earthquakes for this reason a large scale study titled turkish landslide inventory project has been carried out since 1998 during this project some special susceptibility hazard and risk assessments have been performed in this study a landslide susceptibility map of a part of tectonic kelkit valley in the north of central turkey was produced employing binary logistic regression analyses to achieve the most appropriate results some sensitivity analyses were also carried out for this purpose four different data sets were constructed considering conditioning factors used and sampling strategies applied for the training data sets in this study as a consequence of the analyses the most proper outcomes were obtained by using the data set in which continuous topographical parameters and lithological dummy variables were implemented together and 50 of training data set was taken from seed cells at random correct classification percentage and root mean square error rmse values for the validation data for that case were estimated as 84 16 and 0 36 respectively this prediction capability shows that the landslide susceptibility map produced in this research paper can be used for the planning of protective and mitigation measures in the region

failure forecast for large rock slides by surface displacement measurements forecasting the failure of large rock slides is difficult because of nonlinear time dependency and seasonal effects which affect the displacements starting from the accelerating creep theory prop

susceptibility assessment of earthquake triggered landslides in el salvador using logistic regression abstract this work has evaluated the probability of earthquake triggered landslide occurrence in the whole of el salvador with a geographic information system gis and a logistic regression model slope gradient elevation aspect mean annual precipitation lithology land use and terrain roughness are the predictor variables used to determine the dependent variable of occurrence or non occurrence of landslides within an individual grid cell the results illustrate the importance of terrain roughness and soil type as key factors within the model using only these two variables the analysis returned a significance level of 89 4 the results obtained from the model within the gis were then used to produce a map of relative landslide susceptibility

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

estimating the quality of landslide susceptibility models we present a landslide susceptibility model for the collazzone area central italy and we propose a framework for evaluating the model reliability and prediction skill the landslide susceptibility model was obtained through discriminant analysis of 46 thematic environmental variables and using the presence of shallow landslides obtained from a multi temporal inventory map as the dependent variable for statistical analysis by comparing the number of correctly and incorrectly classified mapping units it is established that the model classifies 77 0 of 894 mapping units correctly model fitting performance is investigated by comparing the proportion of the study area in each probability class with the corresponding proportion of landslide area we then prepare an ensemble of 350 landslide susceptibility models using the same landslide and thematic information but different numbers of mapping units this ensemble is exploited to investigate the model reliability including the role of the thematic variables used to construct the model and the model sensitivity to changes in the input data by studying the variation of the model s susceptibility estimate the error associated with the susceptibility assessment for each mapping unit is determined this result is shown on a map that complements the landslide susceptibility map prediction skill of the susceptibility model is then estimated by comparing the forecast with two recent event inventory maps the susceptibility model is found capable of predicting the newly triggered landslides a general framework for testing a susceptibility model is proposed including a scheme for ranking the quality of the susceptibility assessment

influence of large scale topography on gravitational rock mass movements new insights from physical modeling 1 gravitational slope failures and associated rock mass movements can be observed at various scales in the same area it seems obvious that the different movement scales should be interrelated but their relationships are poorly understood we address this problem using 3 d physical modeling experiments were conducted with mechanically homogeneous models with two scale topographic features a large scale corresponds to the whole mountain several kilometers and a smaller one to a part of a mountain slope one kilometer results show that large scale relief induces large scale large volume gravitational movements introduction of small scale topographic features results not only in the generation of smaller scale landslides but also in considerable changes in the deformation pattern the various scale processes occur simultaneously and affect each other to predict the evolution of a landslide it is therefore necessary to take into account the topography and deformation pattern at various scales

influence of deep seated gravitational slope deformations on landslide distributions a statistical approach abstract the influence of deep seated gravitational slope deformations dsgsds on the distribution of translational landslides was analyzed in the milia basin tuscany italy detailed geomorphological mapping combined with the analysis of aerial photography enabled us to build two landslide inventories one inventory including landslides before 1975 was used to create statistical models whereas the other inventory including landslides after 1975 was used to validate the models geology slope angle slope aspect distance to hydrographic elements and distance to tectonic lineaments were considered as landslide predisposing factors to quantify the importance of dsgsds as another landslide predisposing factor the dsgsd presence absence map was introduced in the stepwise statistical analysis the landslide inventory maps and factor maps were processed using a conditional analysis on all possible factor combinations to produce landslide susceptibility maps with five susceptibility classes the results indicate that the dsgsds significantly affect landslide distribution

spatial statistical modeling of shallow landslides validating predictions for different landslide inventories and rainfall events abstract statistical models that exploit the correlation between landslide occurrence and geomorphic properties are often used to map the spatial occurrence of shallow landslides triggered by heavy rainfalls in many landslide susceptibility studies the true predictive power of the statistical model remains unknown because the predictions are not validated with independent data from other events or areas this study validates statistical susceptibility predictions with independent test data the spatial incidence of landslides triggered by an extreme rainfall in a study area was modeled by logistic regression the fitted model was then used to generate susceptibility maps for another three study areas for which event based landslide inventories were also available all the study areas lie in the northern foothills of the swiss alps the landslides had been triggered by heavy rainfall either in 2002 or 2005 the validation was designed such that the first validation study area shared the geomorphology and the second the triggering rainfall event with the calibration study area for the third validation study area both geomorphology and rainfall were different all explanatory variables were extracted for the logistic regression analysis from high resolution digital elevation and surface models 2 5 m grid the model fitted to the calibration data comprised four explanatory variables i slope angle effect of gravitational driving forces ii vegetation type grassland and forest root reinforcement iii planform curvature convergent water flow paths and iv contributing area potential supply of water the area under the receiver operating characteristic roc curve auc was used to quantify the predictive performance of the logistic regression model the auc values were computed for the susceptibility maps of the three validation study areas validation auc the fitted susceptibility map of the calibration study area apparent auc 0 80 and another susceptibility map obtained for the calibration study area by 20 fold cross validation cross validation auc 0 74 the auc values of the first and second validation study areas 0 72 and 0 69 respectively and the cross validation auc matched fairly well and all auc values were distinctly smaller than the apparent auc based on the apparent auc one would have clearly overrated the predictive performance for the first two validation areas rather surprisingly the auc value of the third validation study area 0 82 was larger than the apparent auc a large part of the third validation study area consists of gentle slopes and the regression model correctly predicted that no landslides occur in the flat parts this increased the predictive performance of the model considerably the predicted susceptibility maps were further validated by summing the predicted susceptibilities for the entire validation areas and by comparing the sums with the observed number of landslides the sums exceeded the observed counts for all the validation areas hence the logistic regression model generally over estimated the risk of landslide occurrence obviously a predictive model that is based on static geomorphic properties alone cannot take a full account of the complex and time dependent processes in the subsurface however such a model is still capable of distinguishing zones highly or less prone to shallow landslides

mass movement geologic structure and morphologic evolution of the pizzotto greci slope calabria italy abstract deep seated mass movements of different types affect the pizzotto greci slope in northwest calabria italy the slope is carved out of phyllitic rocks capped by gneissic layers its geological structure is extremely complicated by tectonic structures that pervasively cross the slope transversely and downslope a large scale gravitational deformation of sackung type affects the slope on the upslope side a debris flow source area feeds a large fan constructed by recurrent debris flow deposits aggradation is consequently occurring along the stream at the base of the slope in order to define the internal structure of the slope for a stability slope model geological geostructural geomorphological historical and dendrogeomorphologic studies as well as direct geotechnical logs and indirect geophysical investigations have been carried out over a two year project financed by the ec environment programme the main aspects of the geological and geomorphological studies and some preliminary geotechnical data are presented here along with a conceptual model aimed at describing the relationships between the mass movements on the slope and the construction destruction stages of the fan at the base of the slope the model is based on the assumption that aggradation has a stabilising effect on the slope thus debris flow activity is reduced and consequently destruction of the fan occurs bringing the slope again towards unstable conditions the reactivation of mass movement however leads to the reconstruction of the fan and the buttressing effect at the base of the slope is restored thus the process is cyclic and self regulating

tectonic vs gravitational morphostructures in the central eastern alps italy constraints on the recent evolution of the mountain range abstract deep seated gravitational slope deformations dsgsds influence landscape development in tectonically active mountain ranges nevertheless the relationships among tectonics dsgsds and topography are poorly known in this paper the distribution of dsgsds and their relationships with tectonic structures and active processes surface processes and topography were investigated at different scales over 100 dsgsds were mapped in a 5000 km2 sector of the central eastern alps between the valtellina engadine and venosta valleys detailed lineament mapping was carried out by photo interpretation in a smaller area about 750 km2 including the upper valtellina and val venosta fault populations were also analysed in the field and their mechanisms unravelled allowing to identify different structural stages the youngest being consistent with the regional pattern of the ongoing crustal deformation finally four dsgsd examples have been investigated in detail by geological and 2d geomechanical modelling dsgsds affect more than 10 of the study area and mainly cluster in areas where anisotropic fractured rock mass and high local relief occur their onset and development is subjected to a strong passive control by mesoscopic and major tectonic features including regional nappe boundaries as well as nw se n s and ne sw trending recent brittle structures the kinematic consistency between these structures and the pattern of seismicity suggests that active tectonics may force dsgsds although field evidence and numerical models indicate slope debuttressing related to deglaciation as a primary triggering mechanism

analysis of the distributions of stress in natural ridge forms implications for the deformation mechanisms of rock slopes and the formation of sackung abstract stress distributions in general asymmetric ridge forms derived from 13 ridges in british columbia and colorado are modelled in two dimensions with a finite difference method in each of the 13 ridges sackung scarps tension cracks trenches can be found spatial correlations between stress concentrations and these sackungen landforms are investigated for the mean ridge forms rock mass properties for the modelled ridges are developed using the hoek brown criterion and the geological strength index gsi gravity loading and combined gravity tectonic loading on the ridge forms are considered the importance of representing in situ rock masses with an elastoplastic as opposed to elastic constitutive criterion is discussed the resulting stress distributions for the three general ridge classes indicate that different processes are responsible for the formation of sackungen landforms and slope deformations in each type of ridge

predicting landslides for risk analysis spatial models tested by a cross validation technique abstract a landslide hazard map is intended to show the location of future slope instability most spatial models of the hazard lack reliability tests of the procedures and predictions for estimating the probabilities of future landslides thus precluding use of the maps for probabilistic risk analysis to correct this deficiency we propose a systematic procedure comprising two analytical steps relative hazard mapping and empirical probability estimation a mathematical model first generates a prediction map by dividing an area into prediction classes according to the relative likelihood of occurrence of future landslides conditional by local geomorphic and topographic characteristics the second stage estimates empirically the probability of landslide occurrence in each prediction class by applying a cross validation technique cross validation a blind test here using non overlapping spatial or temporal subsets of mapped landslides evaluates accuracy of the prediction and from the resulting statistics estimates occurrence probabilities of future landslides this quantitative approach exemplified by several experiments in an area near lisbon portugal can accommodate any subsequent analysis of landslide risk

paraglacial slope adjustment since the end of the last glacial maximum and its long lasting effects on secondary mass wasting processes hauser kaibling austria abstract this study indicates the possible long lasting impacts of deep seated gravitational slope deformation dgsd on erosional and mass movement processes dgsd features are common large scale landforms in the crystalline basement rocks of the central alps of austria inactive forms are related to paraglacial nonglacial processes directly conditioned by former glaciation and deglaciation rock slope adjustment processes acting after glacier retreat towards the end of the late glacial period the near surface metamorphic bedrock of dgsd features is generally disintegrated such rock type favours erosion and the formation of small landslides field data laboratory analyses aerial photographs and gis based terrain analyses are used to describe the different geomorphic effects of an extremely disintegrated rock slope the studied dgsd hauser kaibling 13 6 km2 is located in central austria during the last glacial maximum the adjacent valley glacier reached an altitude of approximately 1900 m a s l glacier retreat in combination with the unfavourable tectono metamorphic setting caused gravity induced stresses to act subsequent sediment build up in the main valley restabilised the slope linear erosion cut a number of gullies into the lower part of the dgsd calculated mean erosional denudation rates at incised valley sections range from 0 5 to 2 6 mm a 1 since deglaciation smaller active landslides on the sides of the steep gullies draining the dgsd contribute to high denudation rates active landsliding is favoured by i fragmented rock ii steep slopes iii supply of surface and subsurface water by rain and snowmelt and iv human impact debris flows and debris charged flood events occurred frequently in the past during such events material was transported from the unstable slopes to the populated alluvial fans thus knowledge about the spatial distribution and the stage of development of dgsds active and currently inactive provides an important basis for risk management measures