model test study on monitoring dynamic process of slope failure through spatial sensor network landslides represent a major type of natural hazards worldwide for development of risk mitigation capabilities an effective system for monitoring dynamic process of slope failure capable of gathering spatially distributed information before during and after a landslide occurrence at real time manner is essential a spatial sensor network ssn which integrates the real time communication infrastructure and observations from in situ sensors and remote sensing platforms offers an efficient and effective approach for such purpose in this paper a ssn based landslide monitoring system was designed and evaluated through a model test study conducted at tongji university china this system munold multi sensor network for observing landslide disaster has been designed as a comprehensive monitoring framework including sensor observations multi channel wireless communication remote data storage visualization data processing and data analysis in this model test study initial experimentation demonstrated the capabilities of the munold system for collecting real time information about the dynamic process and propagation of slope failure innovatively generated from the high speed stereo images the sequential surface deformation vector field can be created and may exhibit the dynamic process during the extremely critical and short period of the slope failure after this model test study the munold system is going to be further improved and extended in a landslide prone region in sichuan province china

impacts of age dependent tree sensitivity and dating approaches on dendrogeomorphic time series of landslides different approaches and thresholds have been utilized in the past to date landslides with growth ring series of disturbed trees past work was mostly based on conifer species because of their well defined ring boundaries and the easy identification of compression wood after stem tilting more recently work has been expanded to include broad leaved trees which are thought to produce less and less evident reactions after landsliding this contribution reviews recent progress made in dendrogeomorphic landslide analysis and introduces a new approach in which landslides are dated via ring eccentricity formed after tilting we compare results of this new and the more conventional approaches in addition the paper also addresses tree sensitivity to landslide disturbance as a function of tree age and trunk diameter using 119 common beech fagus sylvatica l and 39 crimean pine pinus nigra ssp pallasiana trees growing on two landslide bodies the landslide events reconstructed with the classical approach reaction wood also appear as events in the eccentricity analysis but the inclusion of eccentricity clearly allowed for more 162 landslides to be detected in the tree ring series with respect to tree sensitivity conifers and broad leaved trees show the strongest reactions to landslides at ages comprised between 40 and 60 years with a second phase of increased sensitivity in p nigra at ages of ca 120 130 years these phases of highest sensitivities correspond with trunk diameters at breast height of 6 8 and 18 22 cm respectively p nigra this study thus calls for the inclusion of eccentricity analyses in future landslide reconstructions as well as for the selection of trees belonging to different age and diameter classes to allow for a well balanced and more complete reconstruction of past events

monte carlo estimation and resolution analysis of seismic background velocities the complete solution to an inverse problem including information on accuracy and resolution is given by the a posteriori probability density in the model space by running a modified simulated annealing samples from the model space can be drawn in such a way that their frequencies of occurrence approximate their a posteriori likelihoods using this method maximum likelihood estimation and uncertainty analysis of seismic background velocity models are performed on multioffset seismic data the misfit between observed and synthetic waveforms within the time windows along computed multioffset travel times is used as an objective function for the simulated annealing approach the real medium is modeled as a series of layers separated by curved interfaces lateral velocity variations within the layers are determined by interpolation from specified values at a number of sampling points the input data consists of multioffset seismic data additionally zero offset times are used to migrate the reflectors in time to the depth domain the multioffset times are calculated by an efficient ray tracing algorithm which allows inversion of a large number of seismograms the a posteriori probability density for this problem is highly multidimensional and highly multimodal therefore the information contained in this distribution cannot be adequately represented by standard deviations and covariances however by sequentially displaying a large number of images computed from the a posteriori background velocity samples and the data it is possible to convey to the spectator a better understanding of what information we really have on the subsurface

a crustal seismic velocity model for the uk ireland and surrounding seas summary a regional model of the 3 d variation in seismic p wave velocity structure in the crust of nw europe has been compiled from wide angle reflection refraction profiles along each 2 d profile a velocity depth function has been digitised at 5 km intervals these 1 d velocity functions were mapped into three dimensions using ordinary kriging with weights determined to minimise the difference between digitised and interpolated values an analysis of variograms of the digitised data suggested a radial isotropic weighting scheme was most appropriate horizontal dimensions of the model cells are optimised at 40 40 km and the vertical dimension at 1 km the resulting model provides a higher resolution image of the 3 d variation in seismic velocity structure of the uk ireland and surrounding areas than existing models the construction of the model through kriging allows the uncertainty in the velocity structure to be assessed this uncertainty indicates the high density of data required to confidently interpolate the crustal velocity structure and shows that for this region the velocity is poorly constrained for large areas away from the input data

reconstructing recent landslide activity in relation to rainfall in the llobregat river basin eastern pyrenees spain abstract a chronology of recent landslides in the upper basin of the llobregat river eastern pyrenees has been reconstructed from technical reports field reconnaissance and dendrogeomorphological analysis the precipitation conditions responsible for triggering and reactivating landslides have been deduced by analysis of rainfall records from two rain gauges located in the area two different rainfall patterns relate to landslide occurrence i without antecedent rainfall high intensity and short duration rains trigger mostly debris flows and shallow slides developed in colluvium and weathered rocks a rainfall threshold of around 190 mm in 24 h initiates failures whereas more than 300 mm in 24 48 h are needed to cause widespread shallow landsliding ii with antecedent rain moderate intensity precipitation of at least 40 mm in 24 h reactivates mudslides and both rotational and translational slides affecting clayey and silty clayey formations in this case several weeks and 200 mm of precipitation are needed to cause landslide reactivation dendrochronological analysis shows that landslide activity in the eastern pyrenees was relatively low between 1926 and 1959 but has since increased significantly with reactivation now occurring about every 3 years

freshening and dense shelf water reduction in the okhotsk sea linked with sea ice decline abstract a recently constructed hydrographic dataset from the okhotsk sea reveals a prominent freshening to depths of 500 m during the past four decades with the maximum in the northwestern part of the sea averaged over the sea this freshening corresponds to an input of 0 55 m of freshwater this leads to a decrease in density of the intermediate water and deepening of the isopycnals with the maximum deepening at 26 8 of 60 m averaged over the sea the intermediate water is significantly warmed along the pathway of dense shelf water dsw a simple box model shows that dsw production has decreased by 30 during the past four decades we propose that the freshening and dsw reduction are caused by the weakening of salt freshwater redistribution through sea ice decline as well as by the increase of excess precipitation over evaporation since the overturning in the north pacific originates from the okhotsk sea through the dsw these changes possibly weaken the shallow overturning of the north pacific

the relationship between seismic velocity and density in the continental crust a useful constraint summary plots of seismic velocity and density of rock samples show that a range of densities is possible for rocks of each seismic velocity and vice versa although a single linear relationship is often assumed in crustal gravity calculations because of the scatter whenever rocks of known seismic velocity are converted to density using this relationship a reduction is made to the resolving power of the resulting gravity calculation if these rocks reach thicknesses of more than a few kilometres then the uncertainties become significant when compared with the size of commonly observed gravity anomalies examples are considered from the north sea mississippi and carolina trough it is concluded that the use of a seismic velocity measurement as the only indication of rock density does not provide a useful constraint when attempting to reproduce observed gravity variations an appropriate model for isostatic compensation is probably the most important factor for successful predictions of crustal structure on the basis of gravity data

crustal structure of the central and southern north sea from birps deep seismic reflection profiling through the generous gift of shiptime on m v mobil search in june 1987 birps british institutions reflection profiling syndicate was able to acquire nearly 1500 km of deep seismic profiles recorded to 16s twt in a regional survey across the central and southern north sea reflective lower crust beneath the southern north sea basin gives way laterally to a zone of mid crustal reflections within the london brabant platform these mid crustal reflectors are interpreted as due to crustal shearing although whether related to stretching during basin formation or to some earlier event remains enigmatic sub crustal sw dipping reflections are observed at the edge of the london brabant platform across the mid north sea high n s profiles show distinctive patterns of lower crustal reflectivity that indicate lateral variability in structure and character on a scale of 30 50 km these are interpreted as crustal units relating to the iapetus suture developed during the caledonian orogeny they may have been modified however during carboniferous basin development or subsequently the absence of any distinctive sub crustal reflectors associated with the iapetus suture where a caledonian subduction zone should have existed tends to suggest that sub crustal reflections observed elsewhere around britian are not subduction related but are more likely to be from younger faults or shear zones relating to lithosphere extension and basin formation onshore wide angle recording in northern england of the marine seismic source produced good quality data the high resolution obtained has revealed details of mid crust pcp and moho pmp reflections from around 18 and 30 km depth respectively not observed before in this area both reflectors show events of laterally variable reflectivity that appear as bands of discontinuous reflection segments

dendrogeomorphic reconstruction of flash floods in the patagonian andes flash floods represent a significant natural hazard in small mountainous catchments of the patagonian andes and have repeatedly caused loss to life and infrastructure at the same time however documentary records of past events remain fairly scarce and highly fragmentary in most cases in this study we therefore reconstruct the spatiotemporal patterns of past flash flood activity along the los cipreses torrent neuquen argentina using dendrogeomorphic methods based on samples from austrocedrus chilensis pseudotsuga menziesii and nothofagus dombeyi we document 21 flash flood events covering the period a d 1890 2009 and reconstruct mean recurrence intervals of events at the level of individual trees being impacted which varies from 4 to 93 years results show that trees tend to be older younger in sectors of the torrent with gentler steeper slope gradients potential triggers of flash floods were analyzed using daily temperature and precipitation data from a nearby weather station weather conditions leading to flash floods are abundant precipitations during one to three consecutive days combined with temperatures above the rain snow threshold 2 c in the whole watershed

progress in birps deep seismic reflection profiling around the british isles abstract the results of 4000 km of new birps profiles are briefly outlined as an introduction to other birps papers in this volume highlights of these profiles include the tracing for 900 km of a reflection pattern in the lower crust associated with the lapetus suture and the observation of more than 20 separate reflections from the mantle while progress in solving the problem of deep water multiples has enabled the joining of the continental and oceanic moho reflections off sw england developments in old interpretational problems are reviewed and the new problem of dating reflections is mentioned

climate change increases frequency of shallow spring landslides in the french alps in this contribution past process activity is reconstructed on seven landslide bodies of the riou bourdoux catchment southeastern french alps based on an unusually dense data set of 3036 tree ring series extracted from 759 conifers we provide evidence for 61 landslide reactivations since a d 1898 based on logistic regressions and threshold analyses of monthly rainfall data and temperature anomalies we determine that the combination of snow rich winters and positive temperature anomalies in spring enhanced snowmelt seems to have driven landslide reactivations in the past since the early 1990s however landslide reactivations clearly have been on the rise and thereby exhibit excessive and unprecedented rates of activity 12 5 events per 10 yr at the scale of the riou bourdoux catchment from the data evidence exists for a shift from snowmelt induced landslides controlled by winter precipitation to reactivations controlled by spring temperatures therefore this contribution also adds evidence to the hypothesis that climate change and related warmer springs could further enhance landslide activity in the course of the 21 st century

historical evolution of slope instability in the calore river basin southern italy abstract there is interest in knowing historical spatio temporal patterns of landslide activity however this is challenging to reconstruct because it is difficult to obtain detailed records for past landslide activity here we deal with hydro geomorphological signatures such as storms downpours floods snowmelt and mass movement to detect annual slope instability events asies over historical times in order to obtain asies for each year a monthly instability density index idi was used and then monthly values were summed up to obtain a yearly value classes of monthly idi varying between 0 no instability and 4 highest instability were determined from historical documents we present an application for the calore river basin southern italy using data from a 313 year long series 1701 2013 ce after 1880 ce the information becomes more valuable with directly observed landslide frequency by this cataloguing 129 asies were obtained their evolution shows slight instability during the 18th century uneven and greater slope instability occurred instead across the 19th century when an important phase of deforestation coincided with intensification of agricultural activities slope instability events continued during the 20th century but their causes are mainly related to anthropisation and the effects of recent climate change it was determined that stormy autumns until the 19th century and successive winter times with enhanced snowmelt may have driven the reactivation of widespread instability events we also found that mountainous and hilly terrains have an acute sensitivity to climate change

seismic attenuation in the continental crust sw of england summary significant variability in crustal attenuation exists off england s sw coast as shown by birps deep seismic reflection lines the presence of the thick cornubian batholith with no sedimentary cover acting as a low attenuating region compared to normal upper crust with about 300 m of sedimentary cover can account for the observed differences in the strength of signal returning from the lower crust application of the spectral amplitude ratio method to determine the effective quality factor q of the lower crust beneath the granite yields a value of 400 200 a modification of the spectral amplitude ratio method to measure relative q s at different locations indicates that the average q of the upper and middle crust containing the granite is twice that elsewhere although the hypothesis that the lower crustal composition differs significantly beneath the granite cannot be ruled out geological and seismic observations suggest that differential attenuation is the main factor causing variation in the observed reflectivity thus thick granites act as low attenuating windows to the lower crust

study of the crystalline crust from a two ship normal incidence and wide angle experiment abstract in 1992 british institutions reflection profiling syndicate conducted a two ship coincident near vertical and wide angle experiment to determine the detailed velocity structure of the continental crust in the central north sea the results show a near surface high velocity gradient layer p wave velocity reaches 6 0 km s at 5 km depth a high velocity zone 6 5 km s at 10 15 km depth a 19 km thick upper crust and the moho at a depth of 32 34 km along the 135 km profile the travel time and amplitude of wide angle data require the presence of a dipping reflector originating at the moho 32 km depth and continuing down to 38 km in the mantle the velocity between 19 and 24 km depth is slightly lower 6 1 km s than that in the upper crust the waveform modelling of the combined normal incidence and wide angle data requires a number of alternating high and low velocity layers in the lower crust 19 33 km the velocity contrast in the lower part of the lower crust 29 33 km is large of the order of 1 km s 6 5 7 5 km s there are a few alternating high 8 2 km s and low velocity 7 5 km s layers in the upper part of the mantle 33 36 km the high velocity 6 5 km s in the upper crust may be due to a high grade of metamorphism and it may have been formed during the subduction process the low velocity 6 1 km s in the upper part of the lower crust might be caused by the presence of meta sediments the large velocity variations 6 5 7 5 km s in the lower part of the lower crust suggest the presence of mafic materials and may result from under plating of mafic materials from the mantle the fractionation of melt can also produce the layering in the upper part of the mantle that is observed from seismic analyses

moho beneath the north sea compared on normal incidence and wide angle seismic records the mohorovicic discontinuity the moho is properly defined as the step in the velocity of horizontally travelling p waves from about 7 km s 1 to about 8 1 km s 1 its detailed structure varies from place to place but it is universally interpreted as the transition from crust to mantle normal incidence reflections originating at about moho depth have been reported sporadi cally during the past 20 yr during the past 10 yr continuous seismic reflection profiles have been obtained to this depth both on the continents and in the deep sea and at the same time striking improvements have been made in the methods available for interpretation of refraction experiments here we report a comparison between the moho determined by a long range refraction experiment across the north sea and the results of a short normal incidence reflection profile shot along the same line fig 1 we believe this to be the first time that such a direct comparison has been made

regional tree ring based chronology of landslides in the outer western carpathians abstract landslides are a type of mass wasting and denote any downslope movement of soil and rock under the influence of gravity as such they can represent a dangerous natural hazard process especially in case that they affect inhabited areas or transport infrastructure because the occurrence of landslides is typically favoured by terrain and lithological conditions the process is frequently concentrated in relatively small isolated regions exhibiting suitable initial conditions of terrain instability extensive regional assessments of landslide activity have been used in the past to uncover common triggers and process patterns mostly in the aftermath of large regional disasters by contrast however regional reconstructions of past landslide activity have not been realized with dendrogeomorphic techniques and with the aim to date past landslide histories over extended time periods and with annual dating precision this study therefore aims at disentangling landslide dynamics at the regional scale covering ca 600 km2 by using growth ring records of trees that grow on active landslides the studied area of the host nsko vsetinska hornatina mts central europe is well known for its high landslide activity but has so far been lacking a detailed chronology of past events to this end we dated past activity on 26 landslide bodies using tree ring series from 1322 disturbed trees to reconstruct 327 landslide reactivations during the last century the reconstructed landslide database allowed correlations between landslide types and their frequencies or occurrence as well as inferences between selected morphometric parameters with landslide frequency and magnitude we also observe periods of increased landslide activity 1940s 1960s 1980s and 1990s and events of regional importance e g 1961 1985 and 1997 as well as a significant decrease in landsliding during the last two decades

geophysical investigation of a large landslide in glaciolacustrine clays in the trieves area french alps abstract slope movements in clay deposits are spread all over the world and result from complex deformation processes including internal strains in the landslide body and slipping along rupture surfaces such mass movements are likely to generate changes in the geophysical parameters characterizing the ground which can be used to map the landslide body in the last decade geophysical techniques have been increasingly used for landslide investigation purposes however the success of any geophysical technique is overall controlled by the existence of a geophysical contrast differentiating the body to be mapped for landslides affecting thick clay materials from soft clay to shale or marl electrical and seismic techniques have been mainly applied in the past in this study we attempt to physically characterize the deformation within a large slide avignonet affecting laminated clays which were deposited in a glacially dammed lake during the wurm period clay deposits which cover an area of 300 km2 south of grenoble french alps and have a maximum thickness of 200 m overlay compact alluvial layers and marly limestone of mesozoic age piezometric data at avignonet show that the water table is very shallow implying that the slide developed in saturated clay several seismic and electrical profiles were performed in order to tentatively correlate the variations of p wave vp velocity s wave velocity vs and electrical resistivity with geotechnical data and morphological observations in such saturated and fine material it turned out that only the s wave velocity exhibits significant variations with the displacement rates and the morphological features vs values at shallow depth were found to be inversely correlated with displacement rates measured by gps with a division by at least a factor of 2 between the zones unaffected and strongly deformed by the landslide these results suggest that vs mapping could provide valuable information on the deformation state of the clay material and that the evolution of vs with time could be used as an indicator for characterizing the landslide activity in the subsurface including the evolution into a flow

what drives the southward drift of sea ice in the sea of okhotsk abstract the sea of okhotsk is the southernmost sea ice zone with sizable ice it is widely believed that the prevailing northwesterly wind and the southward east sakhalin current esc are the two main factors that drive the southward drift of sea ice however the relative contributions of these factors have not been understood in this paper by using the current and ice drift data measured with the moored acoustic doppler current profiler a 3 d ocean model simulation objective analysis data of the wind and satellite sea ice data we examine to what degree and how the ice drift is determined by the wind and ocean current from a linear regression of the observed ice drift ocean current and wind the wind forced component of the ice drift was best fitted when sea ice is assumed to move with a speed of 1 6 of the geostrophic wind with a turning angle of 17 6 to the left of the wind such a relationship was adopted as the wind drift component for all sea ice pixels detected from special sensor microwave imager data for the ocean forced component of the ice drift we adopted the current at 20 m depth from a numerical model simulation that reproduces well the esc and its variability we then evaluated the sea ice drift over 46 54 n during 1998 2005 for the southward drift of sea ice the contribution of the wind component is found to be larger than the oceanic component although the ocean contribution becomes larger typically comparable to the wind contribution near the coast and in the northern region where the esc is stronger we estimated the average annual cumulative southward ice transport to be 3 0 0 9 10 11 m 3 at 53 n this ice transport is comparable to the annual discharge of the amur river the ratio of wind to oceanic components in the transport is estimated to be 1 2 1 8 we also conducted ice drift simulations based on the modeled current velocity and the assumed wind drift of 1 5 geostrophic wind with a turning angle of 15 to the left the simulations reproduce well the ice drift north of 47 n but not south of 47 n likely due to the poor representation of the current system at the latter underevaluation of the wind factor near the ice edges and the neglect of ice formation and melt

the deep structure of northern england and the iapetus suture zone from birps deep seismic reflection profiles the nec deep seismic reflection profile images structures in the lower crust which represent the iapetus suture zone beneath southern scotland and northern england on the basis of reflectivity characteristics of the lower crust and reflection moho we recognize four different crustal zones which correspond to four crustal terrane types midland valley zone a a sub continental subduction complex zone b lake district zone c and midland platform zone d the junctions between each of these zones are interpreted as being tectonic a and b originate from the northern continental margin of the iapetus ocean and are separated from c and d which are derived from a southern continent by strong northerly dipping reflections between approximately 15 and 30 km deep in the crust the structure responsible for these reflections does not displace the reflection moho north of the ab cd junction the base of zone b and base of the reflective crust is marked by a pair of parallel reflectors persistent for a horizontal length of about 55 km these reflectors are interpreted as the top and bottom of a slice of remnant oceanic crust at their northerly limit the deepest of the two parallel reflectors transects the moho to a depth of 6 7 km into the uppermost mantle we suggest that their termination delimits the northerly extent of a decollement or shear zone at the present continental moho the shear zone was active during the late stages of caledonian collision when mantle originally from beneath the southern continent underthrust old and newly created crust of the collision zone

modelling groundwater fluctuations and the frequency of movement of a landslide in the terres noires region of barcellonnette france onn the basis of measurements of hydrological parameters and field monitoring of a landslide in the terres noires in the basin of barcelonnette france a hydrological model was developed describing groundwater fluctuations in relation to precipitation these groundwater fluctuations can be used as input to a stability model in order to assess the temporal frequency of instability of the landslide the calculated groundwater fluctuations which can forecast years with landslide incidents were roughly calibrated against dated movements obtained by dendrochronological research the hydrological system of the landslide can be understood through a three layer sequence a rather permeable colluvial top layer underlain by a less permeable colluvial second layer both overlying the nearly impermeable in situ non weathered black marls terres noires the mean ksat value for the matrix flow in the top layer is 15 7 cm day and in the underlying layer 0 7 cm day however water fluxes in these layers occur by two types of groundwater flow matrix flow obeying darcy s law and more rapid gravitational flow through preferential flow paths increasing the conductivity by a factor of 10 to 100 as cube method ksat measurements revealed the model shows long term yearly fluctuations of the phreatic surface with peaks at the end of winter as well as at the beginning of spring and minimum values during the dry summer period these long term fluctuations are explained by the high drainage capacity of the top colluvial layer and the relatively low vertical water fluxes within the underlying colluvial layer the model shows that maximum critical peak height conditions of the groundwater causing instability occur in wet seasons with at least six consecutive months with high amounts more than 60 mm of precipitation 1997 by john wiley sons ltd

simultaneous velocity and interface tomography of normal incidence and wide aperture seismic traveltime data summary a tomographic inversion technique that inverts traveltimes to obtain a model of the subsurface in terms of velocities and interfaces is presented it uses a combination of refraction wide angle reflection and normal incidence data it simultaneously inverts for velocities and interface depths and it is able to quantify the errors and trade offs in the final model the technique uses an iterative linearized approach to the non linear traveltime inversion problem the subsurface is represented as a set of layers separated by interfaces across which the velocity may be discontinuous within each layer the velocity varies in two dimensions and has a continuous first derivative rays are traced in this medium using a technique based on ray perturbation theory and two point ray tracing is avoided by interpolating the traveltimes to the receivers from a roughly equidistant fan of rays the calculated traveltimes are inverted by simultaneously minimizing the misfit between the data and calculated traveltimes and the roughness of the model this smoothing regularization stabilizes the solution of the inverse problem in practice the first iterations are performed with a high level of smoothing as the inversion proceeds the level of smoothing is gradually reduced until the traveltime residual is at the estimated level of noise in the data at this point a minimum feature solution is obtained which should contain only those features discernible over the noise the technique is tested on a synthetic data set demonstrating its accuracy and stability and also illustrating the desirability of including a large number of different ray types in an inversion

landslides and climatic conditions in the barcelonnette and vars basins southern french alps france research into the climatic causes behind the triggering and reactivation of landslides has been carried out in two basins in the southern french alps where a great many landslides have occurred over more than a century correlations between landslides and climate are sometimes precise and closely related in time at other times imprecise and more distant the better known the type of landslide and the date of its occurrence the greater the correlation may appear be this as it may climate is never the sole cause this paper deals with the limits of the effects of climate

coincident seismic reflection refraction studies of the continental lithosphere a global review nearly 50 coincident seismic reflection refraction studies to depths of at least the moho provide an improved understanding of the continental lithosphere some conclusions include the following 1 a transparent upper crust a common observation on vertical reflection profiles cannot generally be correlated with velocity gradients or low velocity zones rather a commonly transparent upper crust may be explained by short wavelength steeply dipping features in the brittle upper crust and to a lesser degree by signal contamination from source generated noise 2 the reflective lower crust in extensional terranes appears to be characterized by a high average seismic velocity 6 6 7 3 km s and to consist of laminated high and low velocity layers with typical thicknesses of 100 200 m 3 landward dipping reflectors observed in the middle to lower crusts of convergent zones have been identified as paired high and low velocity slabs which represent oceanic crust and mantle accreted via underplating to the continental margin 4 the crust mantle boundary may differ sufficiently when imaged with vertical incidence and wide angle data to justify the retention for the present of the concept of separate reflection and refraction mohos while there is good evidence that these features are coincident within measurement uncertainties in most regions recently recorded data from the basin and range admit the possibility for noncoincidence in that area 5 upper mantle reflections which cannot be migrated into the lower crust remain rare despite isolated unequivocal examples thus the upper mantle appears to be relatively homogeneous at seismic reflection wavelengths and to lack the laminations inferred for the lower crust the wide angle method will likely provide the most reliable information on the velocity structure and physical state of this portion of the lithosphere for some years to come 6 there appear to be clear and consistent basic differences between convergent and extensional terranes which have been identified from coincident experiments these differences may be sufficiently universal to infer the tectonic history of poorly exposed terranes 7 no truly three dimensional coincident experiment i e including three dimensional migration has been conducted but some three dimensional data have been collected using both methods measurements of attenuation poisson s ratio and anisotropy within the crust using coincident data sets remain frontiers

rainfall thresholds for the activation of shallow landslides in the italian alps the role of environmental conditioning factors abstract the aim of the present work is to investigate the role exerted by selected environmental factors in the activation of rainfall triggered shallow landslides and to identify site specific rainfall thresholds the study concerns the italian alps the region is exposed to widespread slope instability phenomena due to its geological morphological and climatic features furthermore the high level of anthropization that characterizes wide portions of the territory increases the associated risk hence the analysis of potential predisposing factors influencing landslides triggering is worthwhile to improve the current prediction skills and to enhance the preparedness and the response to these natural hazards during the last years the italian national research council s research institute for hydro geological protection cnr irpi has contributed to the analysis of triggering conditions for rainfall induced landslides in the framework of a national project the project funded by the national department for civil protection dpc focuses on the identification of the empirical rainfall thresholds for the activation of shallow landslides in italy the first outcomes of the project reveal a certain variability of the pluviometric conditions responsible for the mass movements activation when different environmental settings are compared this variability is probably related to the action of local environmental factors such as lithology climatic regime or soil characteristics based on this hypothesis the present study aims to identify separated domains within the italian alps where different triggering conditions exist and different countermeasures are needed for risk prevention for this purpose we collected information concerning 511 landslides activated in the period 2000 2012 and reconstructed 453 rainfall events supposed to be responsible for the activations then we selected a set of thematic maps to represent the hypothesised landslide conditioning factors and to identify the supposed homogeneous domains within the study area we employed an existing statistical method for the definition of the cumulated event rainfall vs rainfall duration ed thresholds for both the entire catalogue of rainfall events and for the events falling in the separated domains the obtained results contribute to a better understanding of the role exerted by geological pedological and climatic factors in landslides activation and help identifying separated domains where different risk managing strategies should be adopted the proposed methodology can be a valid support for risk reduction strategies planning at regional scale

joint traveltime inversion of wide angle seismic data and a deep reflection profile from the central north sea we report results from the seismic wide angle and broadband survey carried out over the mid north sea high this paper focuses on integrating the information from a conventional deep multichannel reflection profile and a coincident wide angle profile obtained by recording the same shots on a set of ocean bottom hydrophones obh to achieve this integration a new traveltime inversion scheme was developed reported elsewhere that was used to invert traveltime information from both the wide angle obh records and the reflection profile simultaneously results from the inversion were evaluated by producing synthetic seismograms from the final inversion model and comparing them with the observed wide angle data and an excellent match was obtained it was possible to fine tune velocities in less well resolved parts of the model by considering the critical distance for the moho reflection the seismic velocity model was checked for compatibility with the gravity field and used to migrate and depth convert the reflection profile the unreflective upper crust is characterized by a high velocity gradient whilst the highly reflective lower crust is associated with a low velocity gradient at the base of the crust there are several subhorizontal reflectors a few kilometres apart in depth and correlatable laterally for several tens of kilometres these reflectors are interpreted as representing a strike section through northward dipping reflectors at the base of the crust identified on orthogonal profiles by freeman et al 1988 as being slivers of subducted and imbricated oceanic crust relics of the mid palaeozoic iapetus ocean

tectonic evolution of the north sea basin crustal stretching and subsidence summary the lithospheric stretching model for the formation of sedimentary basins was tested in the central north sea by a combined study of crustal thinning and basement subsidence patterns a profile of crustal structure was obtained by shooting a long range seismic experiment across the central graben the main axis of subsidence a seabed array of 12 seismometers in the graben was used to record shots fired in a line 530 km long across the basin the data collected during the experiment were interpreted by modelling synthetic seismograms from a laterally varying structure and the final model showed substantial crustal thinning beneath the graben subsidence data from 19 exploration wells were analysed to obtain subsidence patterns in the central north sea since jurassic times changes in water depth were quantified using foraminiferal assemblages where possible and observed basement subsidence paths were corrected for sediment loading compaction and changes in water depth through time the seismic model is shown to be compatible with the observed gravity field and the small size of observed gravity anomalies is used to argue that the basin is in local isostatic equilibrium both crustal thinning and basement subsidence studies indicate about 70 km of stretching across the central graben during the mid jurassic to early cretaceous extensional event this extension appears to have occurred over crust already slightly thinned beneath the graben and the seismic data suggest that total extension since the early permian may have been more than 100km the data presented here may all be explained using a simple model of uniform extension of the lithosphere

migration why doesn t it work for deep continental data summary conventional migration of deep seismic reflection data often produces disappointingly poor results even when the original unmigrated data are of high quality and are relatively noise free surprisingly deep data often subjectively appear to be best migrated at velocities which are up to 50 less than appropriate interval velocities derived from crustal refraction experiments or directly from stacking velocities the explanation for this behaviour is that near surface features distort and attenuate the seismic wave field and produce apparent discontinuities in deep reflections since these discontinuities are spurious they are not associated with the appropriate large diffractions which real discontinuities at depth would produce during the process of migration reflections are invented in order to cancel out the missing diffractions thereby producing a smiley section which appears overmigrated since the lateral extent of individual smiles increases with increasing migration velocity increasing two way time and increasing seismic wavelength the effect is almost unnoticeable on conventional shallow seismic data but is overwhelming for deep crustal data

evaluation of growth disturbances of picea abies l karst to disturbances caused by landslide movements abstract dendrogeomorphic methods are frequently used in landslide analyses although methods of landslide dating based on tree rings are well developed they still indicated many questions the aim of this study was to evaluate the frequently used theoretical scheme based on the event response relationship seventy four individuals of norway spruce picea abies l karst exhibiting visible external disturbance were sampled on the girova landslide the largest historical flow like landslide in the czech republic this landslide reactivated in may 2010 and post landslide tree growth responses were studied in detail these growth responses were compared with the intensity and occurrence of visible external tree disturbance tilted stems damaged root systems and decapitation twenty nine trees 39 2 died within one to four years following the 2010 landslide movement the trees that died following the landslide movement were significantly younger and displayed significantly greater stem tilting than the live trees abrupt growth suppression was a more frequent response among the dead trees whereas growth release dominated among the live trees only two trees 2 7 created no reaction wood in response to the landslide movement forty four percent of the trees started to produce reaction wood structure after a delay which generally spanned one year some eccentric growth was evident in the tree rings of the landslide year and was significant in the first years following the landslide movement missing rings were observed only on the upper sides of the stems and no false tree rings were observed the results confirm the general validity of event response relationship nevertheless this study points out the limitations and uncertainties of this generally accepted working scheme

multi scale landslide susceptibility analysis along a mountain highway in central taiwan abstract for the past decade climate change has caused increasingly more frequent extreme rainfall events in taiwan during which concentrated and intense rainfall has induced large scale flooding and landslides considering the urgency of protecting isolated villages and residential areas near highways from large scale landslides this study analyzed landslide susceptibility along nantou county road 89 in the upstream region of the wu river in taiwan to assess landslide hazards spatially landslide susceptibility analysis was implemented at the catchment scale to predict landslide susceptibility this study employed an atmospheric general circulation model with downscaling estimation information from boreholes was used to analyze the temporal behavior and complex mechanisms of large scale landslides at the local scale on the basis of the results this paper discusses the different findings from the catchment and local scale analyses for the major large scale landslides the rankings of landslide susceptibility values can be obtained to prioritize the remediation of the landslides and the multiscale landslide susceptibility analysis could be applied to mountain highways with complex landslide hazard

mass movements and tree rings a guide to dendrogeomorphic field sampling and dating abstract trees affected by mass movements record the evidence of geomorphic disturbance in the growth ring series and thereby provide a precise geochronological tool for the reconstruction of past activity of mass movement the identification of past activity of processes was typically based on the presence of growth anomalies in affected trees and focused on the presence of scars tilted or buried trunks as well as on apex decapitation for the analyses and interpretation of disturbances in tree ring records in contrast clear guidelines have not been established with largely differing or no thresholds used to distinguish signal from noise at the same time processes with a large spatial footprint e g snow avalanches landslides or floods will likely leave growth anomalies in a large number of trees whereas a falling rock would only cause scars in one or a few trees along its trajectory based on the above considerations we examine issues relating to the interpretation and dendrogeomorphic dating of mass movements particular attention is drawn to sampling in terms of sample distribution across a study site the actual selection of trees as well as to sample size i e number of trees sampled based on case studies from snow avalanche debris flow and landslide sites we demonstrate that thresholds can indeed improve dating quality and at the same time minimize noise in time series we also conclude that different thresholds need to be used for different processes and different periods of the reconstruction especially for the early stages of the reconstruction when the number of potentially responding trees will be much smaller this paper seeks to set standards for dendrogeomorphic fieldwork analysis and interpretation for different processes of mass movements

basalts water or shear zones in the lower continental crust abstract bright sub horizontal laterally extensive multi cyclic layered reflections have now been recorded in the lower continental crust from many areas in contrast this reflection signature is rare in the continental upper crystalline crust and upper mantle and in the oceanic lithosphere with the present state of knowledge it is sensible to seek a single quantitative explanation for all such layering qualitative explanations for lower crustal layering abound and include igneous metamorphic structural and fluid related models measurements of reflection coefficients from the lower crust place strong quantitative constraints on possible models structurally induced anisotropy metamorphic layering or free fluids cannot realistically produce sufficiently bright reflections igneous layering or the juxtaposition of pre existing heterogeneities by shear zones can produce strong reflections results from crustal xenoliths helium isotope ratios palaeo geothermal gradients and chemistry of flood basalts together with numerical modelling of lithospheric extension and asthenospheric melting suggest that underplating and intrusion of the lower crust with mantle derived mafic igneous rocks is common the apparent spatial relationship between lower crustal layering and continental extension and the strength and continuity of the reflections suggest that underplating related to extension and or elevated mantle temperatures is a good explanation for lower crustal layering

coincident normal incidence and wide angle reflections from the moho evidence for crustal seismic anisotropy abstract we explore the consequences of interpreting wide angle crustal seismic data assuming isotropic models when the real crust may be anisotropic we have used a simple anisotropic model to generate synthetic travel times and have inverted these assuming an isotropic layered model for the crust we show that neglecting the effects of anisotropy can produce estimates of crustal thickness and crustal velocity structure that are significantly in error for realistic levels of anisotropy 10 the error in crustal thickness can be several kilometres and the error in average velocity can be 0 5 km s we show that isotropic inversion of anisotropic data can lead to an apparent mismatch between the position of the moho inferred from normal incidence and wide angle data as an example of such a mismatch we show data acquired over the continental crust offshore the north of scotland the dataset we have modelled includes a wide angle expanding spread profile a conventional ocean bottom seismometer profile a high resolution wide angle onshore offshore experiment a synthetic aperture 16 km offset cdp profile and a conventional deep reflection profile these data show unusually sharp bright and continuous reflections from the moho at all offsets the normal incidence reflection moho and the moho modelled from the wide angle data both show the same lateral structure however they are offset one from the other in normal incidence two way travel time this mismatch is considerably larger than the maximum error expected in the wide angle model and is much greater than the accuracy with which the moho can be picked on the reflection data if we assume that this mismatch is caused by crustal scale seismic anisotropy then the synthetic results indicate that anisotropy in the crust north of scotland is about 7

is climate change responsible for changing landslide activity in high mountains climate change manifested by an increase in mean minimum and maximum temperatures and by more intense rainstorms is becoming more evident in many regions an important consequence of these changes may be an increase in landslides in high mountains more research however is necessary to detect changes in landslide magnitude and frequency related to contemporary climate particularly in alpine regions hosting glaciers permafrost and snow these regions not only are sensitive to changes in both temperature and precipitation but are also areas in which landslides are ubiquitous even under a stable climate we analyze a series of catastrophic slope failures that occurred in the mountains of europe the americas and the caucasus since the end of the 1990s we distinguish between rock and ice avalanches debris flows from de glaciated areas and landslides that involve dynamic interactions with glacial and river processes analysis of these events indicates several important controls on slope stability in high mountains including the non linear response of firn and ice to warming three dimensional warming of subsurface bedrock and its relation to site geology de glaciation accompanied by exposure of new sediment and combined short term effects of precipitation and temperature based on several case studies we propose that the following mechanisms can significantly alter landslide magnitude and frequency and thus hazard under warming conditions 1 positive feedbacks acting on mass movement processes that after an initial climatic stimulus may evolve independently of climate change 2 threshold behavior and tipping points in geomorphic systems 3 storage of sediment and ice involving important lag time effects

the iapetus suture zone in england scotland and eastern ireland a reconciliation of geological and deep seismic data deep seismic profiles in the irish and north seas have successfully imaged crustal structure across the iapetus suture zone a problem with current interpretations is that the reflectors chosen as the suture project to the top of the basement well to the south of the solway line the palaeontologically defined trace of the suture we present a revised interpretation in which a reflectivity boundary common to all the profiles is identified as the leading edge of imbricated avalonian crust in effect the footwall of the suture zone this projects to the surface close to the solway line obviating the need to invoke northward backthrusting of the suture

the cambridge digital seismic recorder for land and marine use abstract the cambridge digital seismic recorder is a simple cheap and versatile recording system for portable equipment the recorder stores data in digital form onto high quality walkman cassette recorders with a capacity of over 5 megabytes per cassette most of the recorder functions are implemented in software so that the system can be adapted for a wide variety of uses we describe its use as the recording system with ocean bottom seismometers for controlled source seismology and as a triggered recorder for micro earthquake recording

probability maps of landslide reactivation derived from tree ring records pra bellon landslide southern french alps probability maps of landslide reactivation are presented for the pra bellon landslide located in the southern french alps based on results obtained with dendrogeomorphic analysis spatiotemporal patterns of past landslide activity was derived from tree ring series of 403 disturbed mountain pine trees growing in the landslide body in total 704 growth disturbances were identified in the samples indicating 22 reactivation phases of the landslide body between 1910 and 2011 the mean return period was 4 5 years given the spatiotemporal completeness of the reconstruction probabilities of landslide reactivation were computed and illustrated using a poisson distribution model and for 5 20 50 and 100 years probability of landslide reactivation is highest in the central part of the landslide body and increases from 0 13 for a 5 year period to 0 94 for a 100 year period conversely probabilities of reactivation are lower at its margins the proposed method differs from conventional approaches based on statistical analyses or physical modeling that have demonstrated to have limitations in the prediction of spatiotemporal reactivation of landslides our approach is in contrast based on extensive data on past landslides and therefore allowed determination of quantitative probability maps of reactivation derived directly from the frequency of past events this approach is considered a valuable tool for land managers in charge of protecting and forecasting people and their assets from the negative effects of landslides as well as for those responsible for land use planning and management it demonstrates the reliability of dendrogeomorphic mapping that should be used systematically in forested shallow landslides

centennial scale process activity in a complex landslide body in the qilian mountains northeast tibetan plateau china abstract mass movements in china typically encompass landslides rockfalls and debris flows and these processes affect almost 70 of all mountain areas of china an improved understanding of geomorphic process dynamics and their drivers and process histories are important prerequisites for a proper assessment and a sustainable management of mountain hazards tree rings have on varied occasions proven to be a reliable tool for the acquisition of data on past mountain hazards here we present the first reconstruction of past landslide activity on a slope in the qilian mountains northeast tibetan plateau china to this end a total of 543 qilian juniper sabina przewalskii kom samples were selected from 239 trees growing on or next to a complex landslide body with the aim to reconstruct past landslide histories at the site the dataset of disturbed trees was complemented with 174 increment cores from 84 reference qilian juniper trees growing on three adjacent yet undisturbed sites based on the dating of the samples and the interpretation of growth disturbances gd in the tree ring series of affected trees we provide the first reconstruction of past landslides as retrieved from a dendrogeomorphic record covering more than a millennium 956 2011 ce results show that the first detectable gd occurred as early as in 1042 ce followed by seven major landslide reccurrences in 1703 1816 1848 1863 1913 1970 and 1982 comparison between our landslide record and a dendroclimatic precipitation reconstruction points to the crucial role of major longer term wet precipitation anomalies on landslide occurrence

landslide databases for climate change detection and attribution abstract a systematic inventory of landslide events over regional spatial scales and through time is required for investigating changes in landslide frequency along side changes in landslide triggers this paper describes the methods used to compile a european wide landslide inventory and some of the methodological and practical obstacles that inhibit better use and development of such inventories we argue that these methods can be used more widely to provide a comprehensive picture of landslide populations and to further enrich our understanding of the impact of climate change and other drivers on landslide frequency and magnitude

seismic imaging of forearc backthrusts at northern sumatra subduction zone forearc tectonics at accretionary convergent margins has variously been studied using analogue and numerical modelling techniques numerous geophysical investigations have targeted the subsurface structure of active forearc settings at convergent margins however several critical details of the structure mode of tectonic evolution and the role forearcs play in the subduction seismic cycle remain to be further understood especially for large accretionary margins in this study we present a high resolution deep seismic reflection image of the northern sumatran subduction forearc near the 2004 december 26 sumatra earthquake epicentral region the profile clearly demarcates the backthrust branches at the seaward edge of the aceh forearc basin along which the inner forearc continues to evolve sharp bathymetric features at the seafloor suggest that the imaged backthrusts are active coincident wide angle seismic tomographic image of the sumatra forearc allows us to image the geometry of the seaward dipping backstop buttress with which the imaged backthrust branches are associated the presence of forearc backthrusting confirms model predictions for the development of backthrusting over seaward dipping backstops the west andaman fault at the seaward edge of aceh basin appears to be a shallow tributary of the backthrust and sheds light on the complex deformation of the forearc uplifting along the backthrust branches may explain the presence of forearc islands observed all along sumatran margin and help further constrain the tectonic models for their evolution moreover if these backthrusts slip coseismically they would contribute to tsunamigenesis and seismic risk in the region

broadband receiver response from dual streamer data and applications in deep reflection seismology a method to process dual streamer data with under and over configuration is presented the method combines the results of dephase sum and dephase subtraction methods in the dephase methods the response of one streamer is time shifted so that the primary arrivals on both streamers are aligned and these responses are then summed or subtracted the method provides a broad spectral response from dual streamer data and increases the signal to noise ratio by a factor of 1 5 testing was done on synthetic data and then applied to a real data set collected by the british institutions reflection profiling syndicate birps its application to a deep seismic reflection data set from the british isles shows that the reflections from the lower crust contain frequencies up to 80 hz suggesting that some of the lower crustal reflectors may have sharp boundaries and could be 20 30 m thick

geological and geotechnical properties of the terres noires in southeastern france weathering erosion solid transport and instability abstract the geological formation known as the terres noires covers large areas of southeastern france between the rhone valley and the pre alpine hills this formation consists mainly of dark marls of the basal upper jurassic these marls are very susceptibility to weathering and are particularly prone to erosion resulting in high solid transport this paper attempts to quantify this transport in experimental catchment areas and shows that a forest cover can play a major role in preventing this type of phenomenon weathering of this formation may also lead to gravity instabilities in fresh marl although this is rare and much more frequently in the surficial weathered material

distribution and formation of okhotsk sea intermediate water an analysis of isopycnal climatological data 1 in order to clarify the distribution and formation of okhotsk sea intermediate water osiw an isopycnal climatological data set based on all of the available historical observations is developed and examined the isopycnal maps clearly show that there are two direct ventilation sources for osiw dense shelf water dsw with cold and fresh properties influenced by sea ice formation in the northwest shelf region and forerunner of soya warm current water fscw which has warm and saline properties originating in the japan sea the cold and fresh water extends southward from the northwest shelf to the shelf slope off sakhalin island it suggests that dsw is transported southward by the east sakhalin current the dsw enters the kuril basin and mixes with fscw and western subarctic water wsaw originating from the north pacific to form osiw the annual mean production rate of dsw estimated from the total volume of dsw over the shelf in spring and summer is 0 67 sv 1 sv 106 m3 s the annual mean volume transport of fscw is estimated to be 0 08 sv on the basis of its cross section area and the current speed assumption of isopycnal mixing yields a mixing ratio of 1 1 0 1 among dsw wsaw and fscw to form osiw we estimate the annual production rate of osiw to be 1 4 sv the corresponding osiw s renewal time is 7 years continued assumption of isopycnal mixing yields a mixing ratio of 0 6 0 4 between wsaw and osiw to form oyashio intermediate water oyiw

lispb revisited a new look under the caledonides of northern britain summary the lithospheric seismic profile in britain lispb shot in 1974 included a 700 km long north south profile of the crust and upper mantle of northern britain the wide angle seismic data from lispb was of exceptional quality and coverage making a reinterpretation using current modelling programs worthwhile this reinterpretation shows that the original crustal model published by bamford et al 1978 satisfies the observed first arrival traveltimes but that further detail of crustal velocity structure may be obtained by model shows strong variations in crustal velocity structure that appear to be correlated with geological and tectonic structures mapped at the surface the new lithospheric model is compatible with the observed gravity field when converted to appropriate densities and the variations in loading along the base of the density model show that the lithosphere is close to local isostatic equilibrium profiles of the variation of velocity and density with depth from the new model are compared with measurements of lewisian rocks made at confining pressures up to 8 kbar allowing the seismic model to be interpreted geologically a synthetic normal incidence profile of the new model is superimposed on the nearby nec deep seismic reflection profile and the features imaged by the two techniques are compared

absolute reflection coefficients from deep seismic reflections abstract many deep seismic reflection profiles show bright sub horizontal layered reflections in the lower continental crust accurate estimates are obtained for normal incidence reflection coefficients for the brightest of these reflections by using a marine seismic acquisition system that has been calibrated using deep water sea bottom multiples minimum bounds are placed upon these reflection coefficients by assuming minimum losses due to scattering anelastic attenuation and geometric spreading reflection coefficients of around 0 1 are obtained from the layered lower crust and around 0 15 from the moho it is argued that constructive interference between successive reflections from a layered sequence of reflectors is often unimportant consequently these coefficients can be used to place useful limits on the absolute acoustic impedance contrasts present at depth