covarying sedimentary and biotic fluctuations in lower middle eocene pyrenean deep sea deposits palaeoenvironmental implications abstract analyses of expanded 1975 to 3330 m thick deep marine ypresian lutetian successions from the pamplona and basque basins w pyrenees demonstrate a recurring pattern of coeval sedimentary and biotic changes intervals rich in resedimented deposits are typified by high latitude planktonic foraminiferal indices whereas intervals devoid of large scale resedimented deposits megabreccias are characterized by low latitude planktonic foraminiferal indices data from the megabreccia free intervals record a reasonably good correlation between the vertical trend of planktonic foraminiferal indices from the two pyrenean basins and the global curve of oxygen isotopes from deep sea records for instance the early eocene climatic optimum and the long lasting late ypresian lutetian cooling are respectively recorded in the studied successions by an increase and by a progressive decline in abundance in low latitude planktonic foraminiferal indices this correlation may support the assumption that changes of planktonic foraminiferal indices in the megabreccia free intervals were forced by global climatic changes the dominance of high latitude planktonic foraminiferal indices in the megabreccia bearing intervals is more difficult to interpret such dominance might record global cooling episodes that resulted in eustatic lowstand resedimentation events however the climatic cooling and sea level fall do not fully explain the characteristics of these intervals a reasonable scenario is that tectonically induced resedimentation processes resuspended large volumes of mud and organic matter which led to the eutrophication of seawater such eutrophication would preferentially affect low latitude oligotrophic planktonic foraminiferal species and lead to a relative or absolute increase in the cosmopolitan opportunistic species that typify high latitude groups

comparison of observed hf radar and adcp measurements and computed tides in the north channel of the irish sea abstract a three dimensional high resolution grid of order 1 km model of the north channel of the irish sea incorporating a one equation turbulence energy submodel to parameterize vertical mixing is used to compute the m2 s2 n2 k1 and o1 tides elevations and currents are compared with observations with particular emphasis on a detailed comparison with current profiles recorded by two acoustic doppler current profilers adcps and hf radar measurements of the surface current the comparison with the hf radar shows small scale spatial variations in both modeled and observed currents superimposed upon the larger scale tidal currents these small scale changes appear to be associated with variations in bottom topography and can only be resolved by using fine grid models or detailed measurements computed m2 current profiles derived from a multiconstituent calculation are in excellent agreement with profiles measured by the adcps however in a single constituent m2 calculation the magnitude of the

atlantic eocene planktonic foraminiferal historical biogeography and paleohydrographic indices abstract analysis of a quantitative and synoptic data base of eocene atlantic planktonic foraminifera has illuminated many facets of foraminiferal faunal structure and composition reflective of bioprovince and useful for empirical establishment of ecologic and paleohydrographic indices tropical indigenes such as the morozovellids turborotaliids subquadrate acarininids and some globigerinathekids dissolve most rapidly along with juveniles of most species tropical faunas are high in diversity and dominance include oxygen minimum indices such as the biserial heterohelicids only in high productivity times such as the middle eocene are dominated by genera with high numbers of species and species consistently typical of warm water regions until the late eocene when faunas include a higher number of middle than lower latitude types truly tropical genera are replaced by subtropical eutrophic indicators such as the globigerinathekids and contract to the florida current region prior to their extinctions at the end of the middle eocene atlantic late paleogene tropical forms first appear in the gulf of mexico at the end of the middle eocene middle latitude faunas include high numbers of chiloguembelinids pseudohastigerinids small and biconvex morozovellids round and globigerinid form acarininids low spired subbotinids in the late middle eocene high spired subbotinids large and typical globigerinids in the late eocene these forms have intermediate dissolution susceptibilities middle latitude faunas are often high in diversity in midddle latitude frontal regions dominance is low even in warm intervals when tropical indigenes increase in number in middle latitude faunas especially in boundary currents low latitude species penetrate temperate areas also during cool eutrophic periods of vigorous circulation such as the late middle eocene typical of temperate slope faunas are high abundances of high spired subbotinids and small sized catapsydracids high latitude faunas are usually low in diversity except in the middle to late eocene when frontal regions were located in the southern labrador sea and over rockall bank typical forms are the low spired subbotinids until the late middle eocene globorotaloids catapsydracids tenuitellids and in the late eocene the biserial heterohelicids indigenous species are the most solution resistant and many are mesopelagic during warmings rare low latitude indices penetrate high latitudes subpolar faunas have greatest affinities with middle latitude faunas at these times

regional test of a model for shallow landsliding landslides mapped in 14 watershed analyses in oregon and washington provide a regional test of a model for shallow landsliding a total of 3224 landslides were mapped in watersheds covering 2993 km2 and underlain by a variety of lithologies including tertiary sedimentary rocks of the coast ranges volcanic rocks of the cascade range and quaternary glacial sediments in the puget lowlands gis geographical information system techniques were used to register each mapped landslide to critical rainfall values predicted from a theoretical model for the topographic control on shallow landsliding using 30 m dems digital elevation models a single set of parameter values appropriate for simulating slide hazards after forest clearing was used for all watersheds to assess the regional influence of topographic controls on shallow landsliding model performance varied widely between watersheds with the best performance generally in steep watersheds underlain by shallow bedrock and the worst performance in generally low gradient watersheds underlain by thick glacial deposits landslide frequency slides km2 varied between physiographic provinces but yielded consistent patterns of higher slide frequency in areas with lower critical rainfall values simulations with variable effective cohesion predicted that high root strength effectively limits shallow landsliding to topographic hollows with deep soils and locations that experience excess pore pressures but that low root strength leads to higher probabilities of failure across a greater proportion of the landscape 1998 john wiley sons ltd language en

an oligocene multi species foraminiferal oxygen and carbon isotope record from odp hole 758a indian ocean paleoceanographic and paleo ecologic implications abstract an oligocene basal miocene zones p19 p22 n4 oxygen and carbon isotope stratigraphy is presented based on mixed benthic foraminiferal faunas and different species of planktic foraminifers from eastern indian ocean odp hole 758a lack of covariance in planktic and benthic 18 o ratios indicates that many oligocene sea level fluctuations including the major fall at 30 ma are not of glacio eustatic origin 18 o values suggest that test morphology is a poor indicator of preferred depth habitat of oligocene planktic foraminifers also some groups show considerable shifts in preferred depth habitat reconstructed surface water temperature was nearly constant during the investigated period but even assuming a large antarctic icecap values are unrealistically low 18 20 c most likely water masses with markedly different oxygen isotopic composition existed this poses great problems for quantitative temperature reconstructions planktic foraminiferal species show similar 13 c ratios indicating well mixed surface waters this contrasts with the strong oxygen isotopic gradient which suggests well stratified surface waters during the oligocene the difference in 13 c ratio between the average ratio of planktic foraminiferal species and the benthic foraminifers 13 c p b shows an inverse relation with the known circulation intensity record and thus with productivity this 13 c pattern is interpreted as being caused by the presence of younger bottom waters at this site during periods with lower temperatures and or larger antarctic ice sheets

landslide susceptibility assessment by bivariate methods at large scales application to a complex mountainous environment statistical assessment of landslide susceptibility has become a major topic of research in the last decade most progress has been accomplished on producing susceptibility maps at meso scales 1 50 000 1 25 000 at 1 10 000 scale which is the scale of production of most regulatory landslide hazard and risk maps in europe few tests on the performance of these methods have been performed this paper presents a procedure to identify the best variables for landslide susceptibility assessment through a bivariate technique weights of evidence woe and discusses the best way to minimize conditional independence ci between the predictive variables indeed violating ci can severely bias the simulated maps by over or under estimating landslide probabilities the proposed strategy includes four steps i identification of the best response variable rv to represent landslide events ii identification of the best combination of predictive variables pvs and neo predictive variables npvs to increase the performance of the statistical model iii evaluation of the performance of the simulations by appropriate tests and iv evaluation of the statistical model by expert judgment the study site is the north facing hillslope of the barcelonnette basin france affected by several types of landslides and characterized by a complex morphology results indicate that bivariate methods are powerful to assess landslide susceptibility at 1 10 000 scale however the method is limited from a geomorphological viewpoint when rvs and pvs are complex or poorly informative it is demonstrated that expert knowledge has still to be introduced in statistical models to produce reliable landslide susceptibility maps

a three dimensional model of diurnal and semidiurnal tides and tidal mixing in the north channel of the irish sea the spatial variability of the m2 s2 n2 k1 and o1 tides are examined using a high resolution model of the north channel of the irish sea the sensitivity of computed currents and elevations to two formulations of the vertical eddy viscosity one involving a turbulence energy submodel and another in which it is computed from the flow field are examined tidal elevation amplitudes and phases are compared at 20 gauges and shown to be in good agreement with observations root mean square rms errors of 7 85 cm 32 turbulence energy model and 7 93 cm 41 flow dependent viscosity model were found for the m2 tide comparable errors were found for the other semidiurnal tides differences in the amplitude errors between the two models are below the uncertainty associated with open boundary forcing and measurement errors and are therefore not statistically significant computed cotidal charts showed good agreement with published cotidal charts derived from observations comparison with observed m2 tidal current profiles suggests that at some locations a more accurate profile is determined with the turbulence model while at others the flow dependent solution is more accurate a comparison of m2 tidal current shear in the vertical showed that the turbulence energy model had a slight bias to underestimate this shear this bias was not found in the flow dependent viscosity model for the other tidal constituents the uncertainty in the accuracy of the currents prevented such a comparison also it is not possible to decide with any confidence which closure method is more accurate due to possible errors in the data and the small number of locations where significant shear is found in the vertical the spatial variability of tidal elevations and currents shows an amphidromic point for the semidiurnal tides but none for the diurnal tides in the northern part of the north channel significant differences in tidal current are found between the north channel and the clyde sea where tidal currents are strong and weak respectively this difference is related to the tidal energy flux in the region which is confined to the north channel the spring neap temporal and spatial variability of tidal turbulence shows a close correlation with tidal current magnitude and water depth this in part explains why the simple flow related viscosity model gives comparable results to those from the turbulence model

a new old approach for shallow landslide analysis and susceptibility zoning in fine grained weathered soils of southern italy abstract rainfall induced shallow landslides involve several geo environmental contexts and different types of soils in clayey soils they affect the most superficial layer which is generally constituted by physically weathered soils characterised by a diffuse pattern of cracks this type of landslide most commonly occurs in the form of multiple occurrence landslide phenomena simultaneously involving large areas and thus has several consequences in terms of environmental and economic damage indeed landslide susceptibility zoning is a relevant issue for land use planning and or design purposes this study proposes a multi scale approach to reach this goal the proposed approach is tested and validated over an area in southern italy affected by widespread shallow landslides that can be classified as earth slides and earth slide flows specifically by moving from a small 1 100 000 to a medium scale 1 25 000 with the aid of heuristic and statistical methods the approach identifies the main factors leading to landslide occurrence and effectively detects the areas potentially affected by these phenomena finally at a larger scale 1 5000 deterministic methods i e physically based models trigrs and trigrs unsaturated allow quantitative landslide susceptibility assessment starting from sample areas representative of those that can be affected by shallow landslides considering the reliability of the obtained results the proposed approach seems useful for analysing other case studies in similar geological contexts

examination of generation mechanisms for an english channel meteotsunami combining observations and modeling abstracton the morning of 23 june 2016 a 0 70 m meteotsunami was observed in the english channel between the united kingdom and france this wave was measured by several tide gauges and coincided

landslide inventory maps new tools for an old problem landslides are present in all continents and play an important role in the evolution of landscapes they also represent a serious hazard in many areas of the world despite their importance we estimate that landslide maps cover less than 1 of the slopes in the landmasses and systematic information on the type abundance and distribution of landslides is lacking preparing landslide maps is important to document the extent of landslide phenomena in a region to investigate the distribution types pattern recurrence and statistics of slope failures to determine landslide susceptibility hazard vulnerability and risk and to study the evolution of landscapes dominated by mass wasting processes conventional methods for the production of landslide maps rely chiefly on the visual interpretation of stereoscopic aerial photography aided by field surveys these methods are time consuming and resource intensive new and emerging techniques based on satellite airborne and terrestrial remote sensing technologies promise to facilitate the production of landslide maps reducing the time and resources required for their compilation and systematic update in this work we first outline the principles for landslide mapping and we review the conventional methods for the preparation of landslide maps including geomorphological event seasonal and multi temporal inventories next we examine recent and new technologies for landslide mapping considering i the exploitation of very high resolution digital elevation models to analyze surface morphology ii the visual interpretation and semi automatic analysis of different types of satellite images including panchromatic multispectral and synthetic aperture radar images and iii tools that facilitate landslide field mapping next we discuss the advantages and the limitations of the new remote sensing data and technology for the production of geomorphological event seasonal and multi temporal inventory maps we conclude by arguing that the new tools will help to improve the quality of landslide maps with positive effects on all derivative products and analyses including erosion studies and landscape modeling susceptibility and hazard assessments and risk evaluations

landslide zoning over large areas from a sample inventory by means of scale dependent terrain units abstract a procedure is proposed to produce landslide distribution zoning maps to be considered preparatory to susceptibility hazard and risk zoning maps based on 1 the results from a statistical multivariate analysis of a landslide inventory which must be available for only a portion of the territory to be zoned and 2 the use of appropriately defined terrain mapping units the units are divided into terrain computational units tcus and terrain zoning units tzus whose size is related to the scale of zoning the procedure comprises three phases calibration validation and prediction the purpose of the prediction phase is the application of a calibrated and validated statistical model in a territory previously recognized as viable on the basis of a priori applicability maps for which no information is available regarding the distribution of landslides or where the information provided by the landslides inventory is unreliable or heterogeneous the proposed procedure is applied to two case studies in southern italy for the analysis and zoning of slow moving landslides at 1 25 000 and 1 100 000 scales respectively the first case study illustrates the applicability of the procedure the aim of the second case study is to address the part of the procedure related to the evaluation of the computational maps at the end of the calibration and validation phases

a three dimensional model of the northwest european continental shelf with application to the m4 tide abstract the solution of the fully nonlinear three dimensional hydrodynamic equations in polar coordinates for tides is developed using a finite difference grid in the horizontal and the galerkin method in the vertical using this method a three dimensional model of the northwest european continental shelf is used to investigate the spatial distribution of the m4 tidal elevations and currants over the shelf computed m4 currents are compared with observations and found to he in good agreement in the celtic sea although there are significant errors in the north sea the reasons for these discrepancies and the spatial and depth variations in the m4 currants are discussed in detail

application of a three dimensional turbulence energy model to the determination of tidal currents on the northwest european shelf a three dimensional turbulence energy tidal model employing a sigma coordinate system through the vertical with a logarithmic type transformation to enhance near bed resolution is used to examine m2 tidal currents on the european continental shelf a no slip bottom boundary condition is applied in the model and vertical eddy viscosity is computed from a turbulence energy closure scheme comparisons of observed and computed current profiles determined using the present model and an earlier model employing a spectral representation davies 1986 in the vertical and a slip bottom boundary condition are made in this spectral model a simple relationship between eddy viscosity and depth mean current was employed these comparisons of current profile suggest that above the near bed layer the spectral model can reproduce tidal currents with a comparable accuracy to that of the present turbulence energy model however in the near bed region the turbulence energy model is significantly more accurate computed spatial distributions of current magnitude turbulence energy intensity and eddy viscosity show similar distributions over the model region suggesting that a relationship between eddy viscosity and current intensity the form used in the spectral model is a valid alternative to using a turbulence energy model turbulence energy intensity in particular exhibits significant spatial variations both horizontally and vertically with surface contours of turbulence corresponding to known positions of tidal fronts

landslide susceptibility assessment what are the effects of mapping unit and mapping method landslide susceptibility assessment forms the basis of any hazard mapping which is one of the essential parts of quantitative risk mapping for the same study area different susceptibility maps can be achieved depending on the type of susceptibility mapping methods mapping unit and scale although there are various methods of obtaining susceptibility maps the efficiency and performance of each method should be evaluated in this study the effect of mapping unit and susceptibility mapping method on landslide susceptibility assessment is investigated when analyzing the effect of susceptibility mapping method logistic regression lr which is widely used in landslide susceptibility mapping and spatial regression sr which have not been used for landslide susceptibility mapping are selected the susceptibility maps with logistic and spatial regression models are obtained using two different mapping units namely slope unit based and grid based mapping units the procedure for investigation of effect of mapping unit on different susceptibility mapping methods is applied to kumluca watershed in bartin province of western black sea region turkey 18 factor maps are prepared for landslide susceptibility assessment in the study region geographic information systems and remote sensing techniques are used to create the landslide factor maps to obtain susceptibility maps and to compare the results the relative operating characteristics roc curve is used to compare the predictive abilities of each model and mapping unit and also the accuracy is evaluated depending on the observations made during field surveys by analyzing the area under the roc curve for grid based and slope unit based mapping units it can be concluded that sr model provide better predictive performance 0 774 in grids and 0 898 in slope units as compared to the lr model 0 744 in grids and 0 820 in slope units this result is also supported by the accuracy analysis for both mapping units the sr model provides more accurate result 0 55 for grids and 0 57 for slope units than the lr model 0 50 for grids and 0 48 for slopes the main reason for this better performance is that the spatial correlations between the mapping units are incorporated into the model in sr while this fact is not considered in lr model

modeling shallow landsliding susceptibility by incorporating heavy rainfall statistical properties abstract we present an index based shallow landsliding susceptibility model which allows explicit incorporation of local heavy rainfall statistical properties the model called quasi dynamic shallow landsliding model qd slam is developed upon a theory for coupled shallow subsurface flow and landsliding of the soil mantle the model uses a quasi dynamic wetness index to predict the spatial distribution of soil saturation in response to a rainfall of specified duration and can take into account the spatial variability of soil properties the rainfall predicted to cause instability in each topographic element is characterized by intensity and duration the incorporation of a scaling model for the rainfall frequency duration relationship provides a parsimonious and robust way to include heavy rainfall statistical properties into shallow landsliding modeling the model is used to determine the return period of the critical rainfall needed to cause instability for each topographic element the model is validated over six different study sites where detailed inventories of shallow landslides are available two study sites are located in the north of taiwan and four are located in the italian alps the sites are characterized by different climates and by different duration of the landslide triggering storms model results are evaluated against the surveyed landslides and compared to those obtained by using a steady state model resembling shalstab it is shown that qd slam improves significantly over the steady state approach in predicting existing landslides as represented in the considered landslide inventory moreover the improvement is higher for the cases where the landslide triggering storm duration is short with respect to the length of time required for every point on a catchment to reach subsurface drainage equilibrium the results of our work highlight the capability of the model to incorporate a robust description of the heavy rainfall properties in the analysis and mapping of shallow landsliding susceptibility by using an index style approach

the biostratigraphy and paleobiology of oligocene planktonic foraminifera from the equatorial pacific ocean odp site 1218 planktonic foraminifera from a continuous oligocene succession with clear magnetochronology and sediment cycles at ocean drilling program site 1218 equatorial pacific ocean were studied in the interval from 27 to 30 ma paragloborotalia taxa are common and we examined their size relative abundance and stable isotopes multispecies stable isotope data indicate the depth habitats of oligocene planktonic foraminifera and suggest that globoquadrina venezuelana and dentoglobigerina globularis were probably mixed layer dwellers with paragloborotaliids recording heavier 18 o signatures consistent with a thermocline habitat cyclic variations in the abundance of paragloborotalia match eccentricity 100 kyr variations in percent carbonate and 13 c suggesting orbitally forced upwelling in the equatorial pacific ocean and that paragloborotalia were responding directly to changes in surface water productivity the high resolution biostratigraphy calibrated to the magnetochronology constrains the extinction of paragloborotalia opima which marks the top of planktonic foraminifera biozone o5 p21b at 27 456 ma the highest occurrence of p opima is associated with a 50 size decrease in paragloborotalia pseudocontinuosa taxa within chron 9n in addition we find the extinction of chiloguembelina cubensis is consistent with other deep sea sections within chron 10n at 28 426 ma marking the o4 o5 p21a p21b boundary

paleoenvironmental evolution of central paratethys sea and lake pannon during the cenozoic abstract deep wells penetrated cenozoic sedimentary record of two different basins 1 oligocene retro arc basin which is buried under the 2 miocene back arc danube basin this study is focused on biotic and abiotic proxies discussed in terms of existing biostratigraphical paleoenvironmental and sedimentological data biotic proxies are represented by palynofacies and biomarkers palynomorphs aom phytoclasts toc pr ph ratio steranes abiotic proxies are represented by inorganic geochemistry e g cia sr ba ga rb th u sio2 al2o3 corg p and enrichment factors the biotic and abiotic proxies helped to refine the knowledge about the changes in redox conditions salinity depositional system and paleoclimate in the study area five temporally different environments are observed 1 sedimentation in the oligocene fragment of the retro arc hungarian paleogene basin that took place on a highly proximal part of the shelf a major dysoxic event connected with humid marsh environment is documented within last rupelian transgression ru4 ch1 ch2 2 after a hiatus the danube basin initiated with early badenian langhian stable oxic to slightly dysoxic shelf with minor salinity changes lan2 ser1 ser2 transgression 3 late badenian early serravallian dysoxic deposition similar in all basins of the central paratethys was influenced by upwelling connected with the ser2 ser3 transgression 4 sarmatian late serravallian dysoxic event associated with subsequent flooding ser3 ser4 tor1 which created shallow marginal marine environment 5 pannonian tortonian messinian sedimentation took place on an oxic shelf of the lake pannon near a fluvio deltaic source most likely represented by the paleo danube delta system

autologistic modelling of susceptibility to landsliding in the central apennines italy in previous research a logistic regression of landslide occurrence on several explanatory variables was fitted and used to map landslide susceptibility for a small area in the central apennines italy here the spatial dependence or spatial correlation in the residuals from the fitted regression model was accounted for by inserting an autocovariate into the model the autocovariate was estimated by applying a gibbs sampler to the susceptibilities for neighbouring pixels as in any landslide susceptibility analysis accuracy was difficult to assess because of the requirement for data on future landslides however by comparing the ordinary logistic model to the autologistic model obtained on the same set of data it was possible to assess the influence of the autocovariate the autocovariate rendered the model simpler because several variables lost their significance and were therefore omitted from the model further areas of high landslide susceptibility estimated from the autologistic model were geographically clustered as one would expect and this may be advantageous in terms of i interpreting the model and ii displaying the results to non experts

gis techniques and statistical models in evaluating landslide hazard geographical information systems gis and numerical cartography may greatly facilitate the development and use of statistical models for the assessment of regional landslide hazard from a small drainage basin located in central italy relevant geological and geomorphological factors were collected and processed by applying gis technology in particular modules were used which both generate high fidelity digital terrain models and automatically partition the terrain into main slope units the resulting information was then analysed by discriminant analysis which enabled landslide hazard and risk to be evaluated in each slope unit although not lacking drawbacks the method proved to be a feasible and cost effective approach to landslide susceptibility assessment and mapping

a three dimensional model of diurnal and semidiurnal tides on the european shelf a three dimensional hydrodynamic model of the continental shelf is used to examine the sensitivity of computed diurnal k1 and o1 and semidiurnal m2 s2 and n2 tidal elevations and currents to changes in eddy viscosity profile friction coefficient and water depth the influence of the tide generating potential is also considered the model uses a standard finite difference grid in the horizontal with a functional approach in the vertical thereby giving a continuous tidal current profile from sea surface to seabed the magnitude of the vertical eddy viscosity depends upon the flow field comparisons are made between model computed profiles and harmonic analyses of 278 current time series at a range of locations in varying water depths with particular emphasis on locations where there are current measurements at a number of points in the vertical a detailed examination of these comparisons shows that frictional effects in the near bed region are particularly important in determining near bed shear and that an accurate specification of water depth is critical for tidal current magnitude the spatial distribution of computed current ellipses shows that the semidiurnal currents are strongest in shallow water with the diurnal currents exhibiting an intensification in the shelf edge region the inclusion of the equilibrium tide is particularly important for the correct determination of the magnitude of the k1 tidal current as well as k1 elevations in the north sea the detailed comparisons show that the magnitude of the tidal currents is correctly determined to within 5 cm s 1 at 220 locations with the model accurately to within 2 cm s 1 reproducing the vertical variation the most sensitive test of a three dimensional model of the tidal current at most locations

processes influencing the internal tide its higher harmonics and tidally induced mixing on the malin hebrides shelf abstract a three dimensional prognostic hydrodynamic model with a turbulence energy submodel is used to examine the spatial distribution of the internal tide in the shelf edge region off the west coast of scotland in the initial series of calculations presented here the model is used in a cross shelf form the model contains all the non linear terms necessary to examine the generation of the higher harmonics of the tide and the generation of very short waves on the density interface near the shelf break initial calculations assuming a homogeneous sea region show a thick turbulent bottom boundary layer generated by bottom friction which reduces the tidal current in the near bed region although above this the flow is essential inviscid with no vertical variation calculations with a specified vertical stratification reduce the thickness of the bottom turbulent layer with an associated change in current profile in the case of specified stratification no internal tides are generated however when the density field is allowed to evolve a significant internal tide is generated with an associated internal shear giving rise to enhanced mixing in regions of largest shear results from the model show that higher harmonics of the internal tide and short internal waves are generated above the shelf break where horizontal mixing processes are important the magnitude of these short internal waves increases with increasing tidal forcing and also depends upon the size of the horizontal diffusion term regions of intense surface and bed turbulence associated with the internal tide are found in the shelf break area suggesting that turbulence energy measurements in this location may be a good test of turbulence closure models however the significant spatial variability associated with these regions shows that an intense measurement campaign is required to avoid significant undersampling

assessment of shallow landslide susceptibility by means of multivariate statistical techniques several multivariate statistical analyses have been performed to identify the most influential geological and geomorphological parameters on shallow landsliding and to quantify their relative contribution a data set was first prepared including more than 30 attributes of 230 failed and unfailed slopes the performance of principal component analysis t test and one way test allowed a preliminary selection of the most significant variables which were used as input variables for the discriminant analysis the function obtained has classified successfully 88 5 per cent of the overall slope population and 95 6 per cent of the failed slopes slope gradient watershed area and land use appeared as the most powerful discriminant factors a landslide susceptibility map based on the scores of the discriminant function has been prepared for ensija range in the eastern pyrenees an index of relative landslide density shows that the results of the map are consistent copyright 2001 john wiley sons ltd language en

the value of google earth for erosion mapping abstract google earth ge has been used in several geomorphological contexts especially in the study of river networks glacial coastal landslides and desert landforms in some cases quantification is possible and landform process relations can be inferred ge has been little used in studies of contemporary soil erosion this brief case study illustrates the potential for quick free and accurate surveys that are particularly valuable as an aid to field work the main drawback of ge is the arbitrary timing of imagery in this case with only 3 years of complete coverage of the study area between 2001 and 2015

remote sensing techniques for landslide studies and hazard zonation in europe abstract an inventory is presented of researches concerning the use of remote sensing for landslide studies and hazard zonation as mainly carried out in the countries belonging to the european community an overview is given of the applicability of remote sensing in the following phases of landslide studies 1 1 detection and classification of landslides special emphasis is given to the types of imagery required at different scales of analysis 2 2 monitoring the activity of existing landslides using g p s photogrammetrical techniques and radar interferometry 3 3 analysis and prediction in space and time of slope failures the different factors required in a landslide hazard study are evaluated and the optimum remote sensing imagery for obtaining each of these factors is indicated examples are given of research work carried out in these three phases from ec countries finally an evaluation is given of the aspects of uncertainty associated with the use of remote sensing data and conclusions are given as to the incorporation of remote sensing techniques within the overall framework of techniques

application of three dimensional turbulence energy models to the determination of tidal mixing and currents in a shallow sea abstract a three dimensional hydrodynamic model using a sigma coordinate grid in the vertical with subgrid scale diffusion represented using a range of turbulence energy closure schemes is used to examine m 2 tidal elevations and currents in the irish sea changes in turbulence energy intensity in particular surface turbulence with variations in mixing length formulation is also considered a no slip condition is applied at the sea bed and the sensitivity of tidal elevations and particular tidal currents to changes in bottom roughness length and formulation of mixing length are examined also detailed comparisons are made with measurements from these comparisons it is evident that the bed roughness has a major influence upon tidal elevations and current profiles in the near bed region near bed currents are also influenced by the form of the mixing length close to the sea bed although its value in the upper part of the water column is of less importance however the vertical variation of turbulent energy in particular its surface value is very sensitive to the mixing length elevations computed with the three dimensional model with various closure assumptions are compared with those from a 2d vertically integrated hydrodynamic model in general the two dimensional model appears to reproduce elevations slightly more accurately than the three dimensional model a hybrid three dimensional model using an identical bed stress formulation to that in a two dimensional model is used as a means to compute currents and turbulence energy intensities while maintaining the same elevation distribution as that computed with a two dimensional model

tidal energy fluxes and dissipation on the european continental shelf the spatial distribution of the energy flux energy dissipation current magnitude and surface elevation amplitude of the major tidal constituents over the northwest european shelf are examined in detail these distributions are obtained from the harmonic analysis of a 6 month three dimensional simulation of 28 tidal constituents the model currents are validated by a comparison of computed tidal harmonics against those derived from a harmonic analysis of up to 278 current time series a similar comparison is performed for tidal elevations based on 257 tide gauges calculations show that for the most significant tidal constituents e g m2 s2 and k2 there is a major energy flux in the deep water along the shelf edge off the northwest of scotland with some energy leaking onto the shelf and into the north sea a second source of energy is across the shelf edge at the southern end of the celtic sea with this energy flux propagating into the irish sea and southern north sea where the majority of the energy is dissipation in the shallow regions significantly different distributions are found for the diurnal and shallow water constituents and the spatial distributions of energy flux and dissipation of the various constituents are considered the accuracy of separating tidal current harmonics using model data of less than a synodic period is examined with reference to the s2 and k2 tide calculations suggest that the accuracy of computed currents comparable to those obtained from observations can be obtained from an analysis of a 60 day period compared with the synodic period for s2 and k2 of 182 days a significant saving in computer time

predicting deposition of debris flows in mountain channels an empirical model for predicting deposition of coarse textured debris flows in confined mountain channels is developed based on field measurements of 14 debris flows in the pacific northwest u s a the model uses two criteria for deposition channel slope less than 3 5 and tributary junction angle greater than 70 the model is tested by predicting travel distances of 15 debris flows in the oregon coast range and six debris flows in the washington cascades u s a the model is further tested on 44 debris flows in two lithological types in the oregon coast range using aerial photos and topographic maps on these flows only the approximate travel distance is known the model can be used by resource professionals to identify the potential for impacts from debris flows key words debris flow deposition travel erosion

a comparative study of dempster shafer and fuzzy models for landslide susceptibility mapping using a gis an experience from zagros mountains sw iran abstract a catchment area at the zagros mountains nw shiraz iran is selected as a test site to comparing the output results of the dempster shafer d s and fuzzy models in landslide hazard mapping lithology slope angle slope aspect land cover and soil depth were considered as landslide causal factors the factor maps were input into a gis and a modified landslide hazard evaluation factor mlhef rating and fuzzy membership functions as well as belief function values were assessed for each class of the factor maps the fuzzy sum product and gamma combination approaches were examined and output maps were assessed based on the known landslides the outputs of fuzzy sum and product combination rules were not reasonable because these approaches classified the area into very high or very low susceptibility zones respectively which were not compatible to the field and factor maps criteria a value of 0 94 yielded the most reliable susceptibility for landslides overlay of the known landslides with the output favorability map showed that the identified landslides were located in the high and very high susceptible zones the output results of the dempster shafer model plausibility belief and uncertainty images were also evaluated based on the known landslides the results of this approach revealed that although it was expected that most of the known landslides correspond the plausibility or the belief map only a few of them supported the case and some landslides were coincided into the disbelief or uncertainty maps it is concluded that in comparison to the fuzzy model the d s model obtains less reliable results for landslide hazard mapping since the belief functions were assigned based on the fuzzy membership functions this might be due to the integration equations used by the model or the number of evidence maps used as input layers

foraminifera from the borehole altdorf se germany proxies for ottnangian early miocene palaeoenvironments of the central paratethys abstract during the ottnangian early miocene the shallow epicontinental sea of the upper marine molasse in the western and central paratethys realm experienced major sea level fluctuation leading to significant environmental changes however the effects of these changes remain largely unexplored because detailed palaeoenvironmental analyses of the respective time interval are scarce we here present a thorough analysis of the benthic foraminiferal composition 36 samples 5616 individuals and 90 taxa from a 105 25 m thick marine ottnangian succession of the borehole altdorf and from two coeval outcrops neuhofen oberschwarzenbach all located in the western central paratethys studies on the planktonic foraminifera and calcareous nannoplankton were conducted as well we show that benthic foraminiferal assemblages clearly differ with regard to species composition diversity indexes relative abundances of infauna epifauna and oxygen indicators we introduce five foraminiferal biofacies which together are suggestive of a transgressive regressive development and several distinct environmental changes from the early to middle ottnangian the planktonic foraminiferal assemblages from altdorf and the central paratethys suggest cold temperate surface water however high nutrient availability and taphonomic factors such as selective dissolution could also have affected the planktonic assemblages in most samples the relative abundance of infaunal epifaunal benthic foraminifera planktonic foraminifera and calcareous nannoplankton clearly indicates nutrient rich waters we did not find indicators for upwelling as a possible source for the nutrient flux and therefore assume that the high nutrient levels indicate large scale river influx in a humid climate based on our foraminiferal biofacies we postulate the presence of a particularly high fluviatile runoff and high organic matter supply resulting in a moderate oxygen depletion of marine bottom waters for the period of relative sea level highstand in the early ottnangian strong oxygen depletion of bottom waters occurs in the middle ottnangian and is mainly caused by salinity stratification and a reduced water exchange to the open ocean during that time moreover our data demonstrate that p b ratios for early and middle ottnangian samples only partially support the palaeobathymetric reconstructions based on the benthic foraminifera we suggest that fluviatile input and estuarine circulation strongly affected the relative abundances of planktonic foraminifera besides tidal and other marine currents

a three dimensional model of the principal tides on the european shelf abstract a three dimensional hydrodynamic model of the continental shelf is used to examine the spatial distribution both elevations and currents of 28 of the major tides in the region tidal constituents in the diurnal and semi diurnal band together with higher harmonics and long period tides are used to illustrate the magnitude and spatial variability of the tides over the shelf comparisons are made between model computed profiles and harmonic analyses of 278 current time series at a range of locations in varying water depths with particular emphasis on locations where there are current measurements at a number of points in the vertical observed and computed tidal elevation amplitudes and phases are also compared at up to 257 shore based and off shore tide gauges these detailed comparisons are used to determine any bias in the model and the accuracy of predicted elevations and currents derived with the model results of these comparisons show that although the diurnal and semi diurnal tidal elevations and currents can be accurately reproduced using a 12 km grid the error in the higher harmonics is significantly larger the fact that the model contains all the non linear terms advection quadratic friction wave drift time varying viscosity necessary to generate these harmonics together with a full set of tidal harmonics in order to have the correct level of friction suggests that potentially it should reproduce these constituents however a rigorous comparison was found to be very difficult because of the rapid variation of the higher harmonics in shallow water which cannot be adequately resolved in the model and possible inaccuracy in the measurements of the small currents associated with the higher harmonics

susceptibility and triggering scenarios at a regional scale for shallow landslides abstract the work aims at identifying susceptible areas and pluviometric triggering scenarios at a regional scale in calabria italy with reference to shallow landsliding events the proposed methodology follows a statistical approach and uses a database linked to a gis that has been created to support the various steps of spatial data management and manipulation the shallow landslide predisposing factors taken into account are derived from i the 40 m digital terrain model of the region an 15 075 km2 extension ii outcropping lithology iii soils and iv land use more precisely a map of the slopes has been drawn from the digital terrain model two kinds of covers prevalently coarse grained cg cover or fine grained fg cover were identified referring to the geotechnical characteristics of geomaterial covers and to the lithology map soilscapes were drawn from soil maps and finally the land use map was employed without any prior processing subsequently the inventory maps of some shallow landsliding events totaling more than 30 000 instabilities of the past and detected by field surveys and photo aerial restitution were employed to calibrate the relative importance of these predisposing factors the use of single factors first level analysis therefore provides three different susceptibility maps second level analysis however enables better location of areas susceptible to shallow landsliding events by crossing the single susceptibility maps on the basis of the susceptibility map obtained by the second level analysis five different classes of susceptibility to shallow landsliding events have been outlined over the regional territory 8 9 of the regional territory shows very high susceptibility 14 3 high susceptibility 15 moderate susceptibility 3 6 low susceptibility and finally about 58 very low susceptibility finally the maps of two significant shallow landsliding events of the past and their related rainfalls have been utilized to identify the relevant pluviometric triggering scenarios by using 205 daily rainfall series different triggering pluviometric scenarios have been identified with reference to cg and fg covers a value of 365 mm of the total rainfall of the event and or 170 mm d of the rainfall maximum intensity and a value of 325 mm of the total rainfall of the event and or 158 mm d of the rainfall maximum intensity are able to trigger shallow landsliding events for cg and fg covers respectively the results obtained from this study can help administrative authorities to plan future development activities and mitigation measures in shallow landslide prone areas in addition the proposed methodology can be useful in managing emergency situations at a regional scale for shallow landsliding events triggered by intense rainfalls through this approach the susceptibility and the pluviometric triggering scenario maps will be improved by means of finer calibration of the involved factors

oligocene planktonic foraminiferal biostratigraphy and paleoclimatic interpretation from hole 538a dsdp leg 77 gulf of mexico abstract a relatively extended oligocene pelagic sequence with good to medium recovery drilled during dsdp leg 77 in the gulf of mexico yielded rich and well diversified planktonic foraminiferal faunas planktonic foraminifera recorded in hole 538a span the interval from zone p19 through p22 evolutionary lineages were observed among the globoquadrinids the globigernitids and the globigerina ciperoensis and globigerinoides primordius groups quantitative analysis of planktonic foraminiferal assemblages shows that faunas fluctuate in abundance and species diversity throughout the sequence a few of these fluctuations that could be related to selective dissolution are mainly confined to the early mid oligocene a climatic curve was constructed using a warmer indicators turborotalia pseudoampliapertura globoquadrina tripartita dentoglobigerina globularis dentoglobigerina baroemoenensis globigerina ciperoensis and globigerinoides groups and cassigerinella chipolensis and as cooler indicators catapsydrax spp globorotaloides spp subbotina angiporoides group globigerina s str and the tenuitellids three major intervals are identifiable in the climatic curve interval 1 lower up to zone p20 predominantly cooler interval 2 intermediate up to the upper part of zone p21a with warm and cool fluctuations and interval 3 upper warmer with large positive peak due to abundant g angulisuturalis at the beginning of zone p21b with recooling midway in zone p22 in intervals 1 and 2 planktonic foraminiferal faunas are dominated by temperate forms interpretation of planktonic foraminiferal data suggests that cooler water conditions characterize the early mid oligocene during the mid oligocene most of zone p21a water masses exhibit peculiar characteristics transitional to the warmer waters prevailing during the late oligocene warmer conditions were not definitely settled in zone p22 however as indicated by the cooler episode following the warmest peak these climatic trends are inconsistent with those inferred from oxygen isotopes except at small scale in fact oxygen isotope values for oligocene atlantic ocean are too heavy thus too cool in comparison with the high abundance and diversity of warm taxa especially in zone p22 when values are lighter warmer as in zone p19 abundance and diversity of warm indices are too low to explain such a cool isotope values in presence of highly diversified and abundant warm planktonic foraminifera we suggest 1 that the oxygen isotope ratio used for estimating oligocene paleotemperatures might be 1 heavier than eocene values and further increased for the late oligocene this hypothesis implies the presence of a relatively extended ice cap in antarctica in the early and mid oligocene and probably an increase in ice volume during the late oligocene 2 heavier isotope values might be related to an increase in salinity or 3 by a combination of both ice cap and increase in salinity

palaeoclimatic interpretation based on middle miocene planktonic foraminifera the silesia basin paratethys and monferrato tethys records a comparative study of the distribution and palaeoclimatic interpretation of temperature related taxa of middle miocene planktonic foraminifera from the paratethys silesia basin southern poland and tethys monferrato area northwestern italy is presented the time span considered badenian langhian serravallian is the last period of significant connection between the paratethys and mediterranean tethys even though the depositional conditions water circulation and connection with the oceanic realm were not always favourable to the life and preservation of significant planktonic foraminiferal taxa the silesia basin located in the western segment of the karpathian foredeep is filled by an autochthonous non folded cover of miocene deposits four stratigraphic sections were studied in this area characterised by carpathian sandy deposits of the klodnica formation lower badenian unbedded marly clays marls and strongly bedded lithothamnium marls skawina formation middle badenian anhydrite and laminated clay shales krzy anowice formation upper badenian unbedded marly clays followed by fine grained sands sandy limestone layers and bioclastic levels rich in molluscs and calcareous algae gliwice formation the monferrato area corresponds to the northwestern termination of the apennines thrust belt and consists of an eocene miocene mainly terrigenous succession resting unconformably on upper cretaceous and eocene ligurian flysch three stratigraphic sections are studied in the eastern area characterised by late oligocene to early burdigalian deepwater terrigenous sediments marne di antognola formation followed unconformably by early to middle miocene carbonate sediments originating in a foramol platform depositional environment pietra da cantoni group and by grey whitish glauconitic marls of the marne di mincengo formation late langhian serravallian twenty three species of tethys and paratethys planktonic foraminifera were grouped in cold globigerina bulloides globigerina quinqueloba globigerina praebulloides gr globorotaloides spp catapsydrax spp cold temperate zeaglobigerina woodi z brazieri globorotalia scitula gr globorotalia bykovae warm globigerinoides spp orbuliniforms including praeorbulina spp and orbulina spp globigerina ciperoensis dentoglobigerina altispira gr velapertina indigena globorotalia praemenardii and warm temperate indices paragloborotalia siakensis gr dentoglobigerina baroemoenensis gr globoquadrina praedehiscens and g dehiscens tenuitellinata angustiumbilicata globigerinella obesa globigerina venezuelana their relative abundance was used to reconstruct palaeoclimatic curves comparison of the palaeoclimatic curves makes it possible to recognise a climatic change from warmer conditions in the langhian towards relatively colder conditions in the serravallian the fall in warm related taxa was much more pronounced in the silesia basin than in the monferrato area this palaeoclimatic evidence may be interpreted as the beginning of a series of oscillations pointing to a period of cooling corresponding to one of the major global changes in the palaeoclimatic palaeoceanographic history of the cenozoic i e the mid miocene event mi3 miller et al 1991 paleoceanography 6 33 52

framework for susceptibility analysis of layered rock slopes considering the dimensions of the mapping units and geological data resolution at various map scales abstract in taiwan the failure of rock slopes has caused the catastrophic loss of lives and property to understand the risks associated with rock slope failure susceptibility analysis has been widely adopted as a fundamental task however currently most susceptibility analyses have investigated only landslide occurrences and have been limited to the regional scale in this case susceptibility maps cannot provide detailed information about the rock slope stability as required by the engineers to fill this gap this study developed a methodological framework to analyze the susceptibility of layered rock slopes from regional to local scales in each map scale the appropriate size of the slope unit su was produced as the mapping unit through the object based image analysis obia method and the susceptibility map was generated with an explicit purpose according to the resolution of geological data multiscale susceptibility analysis of layered rock slopes was performed in a metamorphic area in northern taiwan the performance of the susceptibility maps was validated by the field investigations and the data of the geologically sensitive area which were released by the central geological survey of taiwan the results show that different phases of the evaluation of rock slope stability were addressed including the landslide activity and the rock slope characterization on the regional scale and the failure mechanisms on the local scale in addition suitable sus can also be semiautomatically reproduced by the obia method with suggested strategies

multidisciplinary investigations in evaluating landslide susceptibility an example in the serchio river valley italy abstract the proposed experimental study is aimed at contributing to the landslide susceptibility evaluation using a multidisciplinary approach geological geomorphological and geo engineering survey together with multivariate statistical analysis and gis technique it is included in a wider research project aimed at defining the landslide hazard in the area of the map no 250 castelnuovo di garfagnana 1 50 000 scale this study is based on the realization of a landslides inventory map and statistical data analysis using probabilistic methods the methodology applied in ranking slope instability proceeded step by step at first geomorphologic investigation was performed in order to realize a landslide inventory map a gis database was created to collect the characteristics related to landslides geometry type of movement and state of activity geo engineering survey and characterization with in situ and laboratory tests allowed assessing rock mass classification and geotechnical properties of soils texture and consistency the statistical approach for evaluating the landslide susceptibility is based on the assumption that the landslide probability for the currently landslides free areas could be evaluated studying the conditions which led to past and present instability a set of environmental factors thought to be related to landslides were analysed and their spatial distribution organized in different layers then gis supported spatial analysis conditional and multivariate analysis allowed to calculate the connections between instability factors and landslide distribution this step evolved towards two distinct statistical methods both indirect and quantitative leading to a classification of the land surface in some different susceptibility domains conditional analysis was applied to a particular type of terrain unit named unique condition unit ucu that is a unique combination of the instability factors the computer aided evaluation of the landslide index within each ucu represents the probability of landslide occurrence according to bayes statistical concept multivariate analysis was applied to the same set of instability factors but to a different type of terrain unit the grid cell the results showed a quantitative response more reliable about the effectiveness of each instability factors with the possibility of verifying their statistical significance

landslide characteristics and slope instability modeling using gis lantau island hong kong steep terrain and high a frequency of tropical rainstorms make landslide occurrence on natural terrain a common phenomenon in hong kong this paper reports on the use of a geographical information systems gis database compiled primarily from existing digital maps and aerial photographs to describe the physical characteristics of landslides and the statistical relations of landslide frequency with the physical parameters contributing to the initiation of landslides on lantau island in hong kong the horizontal travel length and the angle of reach defined as the angle of the line connecting the head of the landslide source to the distal margin of the displaced mass are used to describe runout behavior of landslide mass for all landslides studied the horizontal travel length of landslide mass ranges from 5 to 785 m with a mean value of 43 m and the average angle of reach is 27 7 this gis database is then used to obtain a logistic multiple regression model for predicting slope instability it is indicated that slope gradient lithology elevation slope aspect and land use are statistically significant in predicting slope instability while slope morphology and proximity to drainage lines are not important and thus excluded from the model this model is then imported back into the gis to produce a map of predicted slope instability the results of this study demonstrate that slope instability can be effectively modeled by using gis technology and logistic multiple regression analysis

landslide zoning in a part of the garhwal himalayas the himalayas are undergoing constant rupturing in the thrust belt zone in the garhwal himalayas due to which earthquake and mass movement activity is triggered these processes of mass movement and landslides have been constantly modifying the landscape landslides are one of the indicators of the geomorphological modifications taking place in this active and fragile terrain this work is aimed at providing another example of landslide susceptibility mapping based on geological and geomorphological attributes the data collected from aerial photographs topographic sheets and the image suggests that there is a correlation between the distribution of landslides and some of the geological and geomorphological factors for example the distance from an active fault relative relief and slope parameters like factor of safety altitude relief slope and the distance from the fault lineament have been included in the study a rating system has been applied to the factors for arriving at a quantitative estimate of landslide susceptibility for each physiographic unit since terrain classification forms the foundation of this work the entire study can be grouped into two sequential activities 1 the terrain classification and 2 landslide susceptibility mapping the result is the landslide susceptibility zoning map presented the landslides have not been classified with respect to time and may represent the final result of the on going geological geomorphological and seismic activity since the holocene period or late pleistocene time when the glaciers retreated

shallow slope failures in clays as a result of decreased evapotranspiration subsequent to forest clearing in the kaministiquia river valley near thunder bay ontario shallow ground movements are common on the grassy slopes whereas the forested slopes generally appear stable these slope failures may

parameterization of soil properties for a model of topographic controls on shallow landsliding application to rio de janeiro a key problem in the use of physically based models of landslide hazards is how to parameterize the representation of soil properties we applied a physically based model for the topographic control on shallow landsliding shalstab to two catchments in rio de janeiro to investigate the accuracy of model results in relation to parameterization of soil properties in so doing we address the relevance of values derived from laboratory tests to the field problem as well as the trade offs inherent in model parameterization we ran the model for all combinations of reasonable cohesion bulk density and friction angle values and compared model predictions to mapped landslides scars we rank sorted model performance through the proportion of the total area of landslide scars correctly predicted as potentially unstable application of the model to an area where soil properties are not well known can be based on either a standard parameterization that emphasizes topographic controls or on local calibration of soil parameters against a map of known landslide locations our analysis suggests that in general acquisition of high quality digital elevation models dems is more important than generation of spatially detailed soil property values for reconnaissance level assessment of shallow landslide hazards

effects of soil depth and subsurface flow along the subsurface topography on shallow landslide predictions at the site of a small granitic hillslope shallow landslides are affected by various conditions including soil depth and subsurface flow via an increase in the pore water pressure in this study we evaluate the effect of soil depth and subsurface flow on shallow landslide prediction using the shallow landslide stability shalstab model three detailed soil depth data the average soil depth weathered soil depth and bedrock soil depth were collected using a knocking pole test at a small hillslope site composed of granite in the republic of korea the shalstab model was applied to a ground surface topographic digital elevation model dem using the three soil depths and upslope contributing area sca assuming subsurface flow calculated from four dems a ground surface topography gsto dem weathered soil topography wsto dem bedrock topography bsto dem and low level bedrock topography ebsto dem the model performance was measured using a receiver operating characteristic roc analysis while evaluating the effect of the soil depth with sca using gsto dem it was found that the bedrock soil depth had higher prediction accuracy compared to that of the average soil depth or weathered soil depth to evaluate the saturated subsurface flow between the soil and bedrock scas calculated using wsto and bsto dems were applied from these simulations we found that sca from bsto dem and the bedrock soil depth affect the shallow landslide prediction however these prediction effects are not significantly increased by large differences in the elevation between the lowest and highest elevation values therefore we considered the influence of the bedrock depression and sca from ebsto dem in applying sca from ebsto the prediction accuracy was significantly increased compared to the other predictions our results demonstrate that the influence of the bedrock topography on the prediction of shallow landslides may be particularly significant at the scale of a hillslope

hazard assessment of rainfall induced landsliding in mexico abstract rainfall induced landsliding represents a major hazard in mexico about 200 municipalities in the states of puebla veracruz and hidalgo were affected by flooding and mass movement processes that resulted from a tropical depression from the atlantic ocean in october 1999 hundreds of slope failures were triggered by intense precipitation which in some localities reached 420 mm during a 24 h period according to official information 263 people died and 1 475 654 inhabitants were affected by flooding and landsliding rainfall event and cycle coefficient defined and the ratios between event and antecedent rainfalls respectively and the mean annual rainfall are summed to give a total coefficient for landslide triggering rainfalls in the sierra norte values for the total coefficient of 0 8 and 0 4 for beginning and end of the wet season respectively appear to be important in addition a hazard assessment was carried out through the development of a landslide susceptibility indicator this was elaborated by using aerial photographs integrating field observations and the coupling of slope instability analysis within a digital elevation model framework field validation indicated that this approach provides a good representation of shallow translational failures 81 of the observed landslides were satisfactorily predicted as potential unstable zones results suggested that this type of dem based hazard assessment can be extremely valuable not only after but also before any landslide related event so that disaster preparedness and planning could be adequately structured

gis based weights of evidence modelling of rainfall induced landslides in small catchments for landslide susceptibility mapping landslide susceptibility mapping is a vital tool for disaster management and planning development activ ities in mountainous terrains of tropical and subtropical environments in this paper the weights of evidence modelling was applied within a geographical information system gis to derive landslide susceptibility map of two small catchments of shikoku japan the objective of this paper is to evaluate the importance of weights of evidence modelling in the generation of landslide susceptibility maps in relatively small catchments having an area less than 4 sq km for the study area in moriyuki and monnyu catchments northeast shikoku island in west japan a data set was generated at scale 1 5 000 relevant thematic maps representing various factors e g slope aspect relief flow accumulation soil depth soil type land use and distance to road that are related to landslide activity were generated using field data and gis techniques both catchments have homogeneous geology and only consist of cretaceous granitic rock thus bedrock geology was not considered in data layering during gis analysis success rates were also estimated to evaluate the accuracy of landslide suscepti bility maps and the weights of evidence modelling was found useful in landslide susceptibility mapping of small catchments

artificial neural networks applied to landslide susceptibility assessment abstract landslide hazard mapping is often performed through the identification and analysis of hillslope instability factors usually managed as thematic data within geographic information systems gis in heuristic approaches these factors are rated by the attribution of scores based on the assumed role played by each of them in controlling the development of a sliding process other more refined methods based on the principle that the present and the past are keys to the future have also been developed thus allowing less subjective analyses in which landslide susceptibility is assessed by statistical relationships between past landslide events and hillslope instability factors the objective of this research is to define a method with the ability to forecast landslide susceptibility through the application of artificial neural networks anns the riomaggiore catchment a subwatershed of the reno river basin located in the northern apennines italy was chosen as an ideal test site as it is representative of many of the geomorphological settings within this region in the present application two different anns used in classification problems were set up and applied one belonging to the category of multi layered perceptron mlp and the other to the probabilistic neural network pnn family the hillslope factors that have been taken into account in the analysis were the following a lithology b slope angle c profile curvature d land cover and e upslope contributing area these factors have been classified on nominal scales and their intersection allowed 3342 homogeneous domains unique condition unit ucu to be singled out which correspond to the terrain units utilized in this analysis the model vector used to train the anns is a subset of that derived from the production of unique condition units and consists of 3342 records organized in input and output variable vectors in particular the hillslope factors once classified on nominal scales as binary numbers represent the 19 input variables while the presence absence of a landslide in a given terrain unit is assumed to be the output variable the comparison between the most up to date landslide inventory of the riomaggiore catchment and the hazardous areas as predicted by the anns showed satisfactory results with a slight preference for the mlp for this reason this is an encouraging preliminary approach towards a systematic introduction of ann based statistical methods in landslide hazard assessment and mapping

a physically based model for the topographic control on shallow landsliding a model for the topographic influence on shallow landslide initiation is developed by coupling digital terrain data with near surface through flow and slope stability models the hydrologic model topog o loughlin 1986 predicts the degree of soil saturation in response to a steady state rainfall for topographic elements defined by the intersection of contours and flow tube boundaries the slope stability component uses this relative soil saturation to analyze the stability of each topographic element for the case of cohesionless soils of spatially constant thickness and saturated conductivity the steady state rainfall predicted to cause instability in each topographic element provides a measure of the relative potential for shallow landsliding the spatial distribution of critical rainfall values is compared with landslide locations mapped from aerial photographs and in the field for three study basins where high resolution digital elevation data are available tennessee valley in marin county california mettman ridge in the oregon coast range and split creek on the olympic peninsula washington model predictions in each of these areas are consistent with spatial patterns of observed landslide scars although hydrologic complexities not accounted for in the model e g spatial variability of soil properties and bedrock flow control specific sites and timing of debris flow initiation within areas of similar topographic control

atlantic eocene planktonic foraminiferal paleohydrographic indicators and stable isotope paleoceanography reconstruction of atlantic ocean vertical and meridional water characteristics is based on combined synoptic fossil census data stable isotope records and measurements of individual planktonic foraminiferal species correlations between planktonic foraminiferal indices and specific water types and or chemical conditions are used to trace seven stages in the history of atlantic circulation during eocene climatic changes 1 warm equable probably saline productive ocean of the early eocene characterized by lowest meridional and vertical thermal gradients and the maximal extent of tropical surface water 2 early middle eocene expansion of subtropical waters and faunas accompanying the first climatic cooling and eutrophication of equatorial surface waters 3 maximal partitioning of water types faunas and bioprovinces in middle eocene zone p11 accompanying maximum planktonic foraminiferal diversity accelerated near surface and deepwater cooling and intensified upwelling 4 latest middle eocene zone p14 maximal planktonic foraminiferal evolutionary overturn during accelerated cooling deep and surface water ventilation and transformation of tropical surface water habitat with the expansion of temperate water types and faunas this accompanied the reduction of meridional heat transport in boundary currents 5 late eocene bottom water and middle latitude cooling broadening of meridional temperature gradients and expanded oxygen minimum but faunal homogenization following the decreased import of mediterranean water ourflow 6 weakening and or shoaling of the nutricline an oxygen minimum and the thermocline preceding a diminution of primary productivity at the eocene oligocene boundary and 7 earliest oligocene low productivty ocean marked by diminished vertical thermal contrasts and homogeneous foraminiferal faunas dominated by small sized individuals the increased areal extent of upwelling with the outcropping of cooler waters over large geographic regions provides an important climatic forcing mechanism in the latest middle and late eocene

stable isotopic study of oligocene miocene sediments from dsdp site 354 equatorial atlantic abstract the oxygen and carbon isotope compositions of planktic and benthic foraminifera and calcareous nannofossils from middle oligocene early miocene equatorial atlantic sediments dsdp site 354 indicate two important paleoceanographic changes in the late oligocene foraminiferal zone p 21 and in the early miocene foraminiferal zone n 5 the first change reflected by a 18o increase of 1 45 inglobigerina venezuelana affected only intermediate pelagic and not surface deep or bottom waters the second change affected surface and intermediate waters whereas deep and bottom waters showed only minor fluctuations in the case of the former the isotope effect of the moderate ice accumulation on the antarctic continent is amplified in the equatorial atlantic by changes in the circulation pattern the latter paleoceanographic change reflected by a significant increase in18o in both planktic and benthic forms about 1 0 and 0 5 respectively may have been caused by ice volume increase and temperature decrease both oxygen and carbon isotope compositions indicate a marked depth habitat stratification for planktic foraminifera and calcareous nannofossils three different dwelling groups are recognized shallowglobigerinoides globoquadrina dehiscens globorotalia mayeri and nannofossils intermediateglobigerina venezuelana and deepcatapsydrax dissimilis the comparison of foraminifera and calcareous nannofossils suggests that the isotopic compositions of nannofossils are generally controlled by the same parameters which control the isotopic composition of shallow dwelling foraminifera but the former are more enriched in18o

marine biotic signals across a late eocene impact layer at massignano italy evidence for long term environmental perturbations the eocene oligocene transition marks the passage from greenhouse conditions to an icehouse state with progressive global cooling starting in the early middle eocene the late eocene presents substantial evidence for extraterrestrial impacts whose effects on living organisms and climatic changes are still not completely clear a high resolution microfloral and faunal investigation has been carried out in a 4 m thick segment of the massignano global stratotype section and point for the eocene oligocene boundary the studied interval includes a late eocene 35 7 0 4 myr old impactoclastic layer containing several cosmic signatures the impact event recorded at massignano had no abrupt dramatic effects on marine biota in terms of extinction however significant quantitative changes in the calcareous plankton and dinoflagellate cyst assemblages occurred 60 kyr after the impact event the observed pattern is intepreted as reflecting a long term re organization of water structure

tidal dynamics in a coupled ocean lake system abstract barotropic tides were studied in the lake maracaibo system venezuela the system consists of two larger water bodies the gulf of venezuela and lake maracaibo connected by the strait of maracaibo and tablazo bay the dominant semi diurnal tide resonates in the gulf and co oscillates roughly 180 out of phase in the lake the narrow strait and shallow bay regulate their dynamical interaction two and three dimensional finite element models are used in conjunction with a fresh analysis of tidal data at seven stations several of which lie in the strait and bay a coupled model of the whole system is necessary to properly interpret these data which show the influence of small scale near field effects superimposed on the larger scale dynamics of the gulf and lake the detailed geometry at the connections with the gulf and the lake also plays a significant role in the local response in the strait and bay co tidal charts are presented for nine major astronomical and shallow water tidal constituents found in the data the velocity structure derived under simple eddy viscosity assumptions is shown to be highly dynamic a characteristic phase lead is found in velocities at depth and near the shore where vertical shear dominates over inertia in the force balance

analysis of horizontally two dimensional morphological evolutions in shallow water a system of depth integrated equations forming a rather primitive mathematical model of horizontally two dimensional 2dh bed evolutions in shallow water is analyzed using characteristics theory the analysis shows that the solution of this system exhibits an essentially two dimensional propagation character with bottom disturbances traveling in other directions than the current velocity and the sediment transport the results of this analysis are verified by numerical experiments and interpreted physically their relevance for numerical modeling of 2dh morphological processes in shallow water is discussed and their occurrence and recognizability in natural situations is checked by a qualitative comparison with field observations

review of recent developments in tidal hydrodynamic modeling i spectral models in this paper we present a brief overview with a comprehensive set of references to recently published papers for detail of a range of techniques used in tidal hydrodynamic modeling and recent progress in the field although the paper aims to introduce the topic to someone new to the area the main emphasis is on new developments in near coastal shallow sea tidal modeling and consequently we concentrate on three dimensional modeling which has progressed significantly in recent years the paper gives a brief account of methods used to discretize the hydrodynamic equations in the horizontal namely finite difference finite element and boundary fitted coordinates and through time the representation of tidal current structure in a three dimensional model using a spectral method in the vertical is also described in this method the subgrid scale vertical diffusion of momentum which has a major influence on tidal current profiles is parameterized using a flow dependent eddy viscosity recent work on

planktonic foraminiferal paleoclimatic implications across the oligocene miocene transition in the oceanic record atlantic indian and south pacific abstract a detailed paleoclimatic investigation was performed on planktonic foraminiferal assemblages spanning the interval from zone p21a late oligocene to zone n5 early miocene in pelagic sequences recovered in dsdp and odp holes in the atlantic south pacific and indian oceans the often rich and well preserved assemblages show that faunas fluctuate in abundance and species richness throughout the sequences from the percent abundances of single taxa at different latitudes biogeographic indices were identified planktonic foraminiferal distribution trends are roughly consistent with the recent species richness is however higher in upper oligocene and lower miocene sequence than it is today northern and southern atlantic bioprovinces were delimited the latter is characterized by cooler climate and by species previously described as endemic to new zealand on the basis of single species or grouped species abundance at low middle and high latitudes and on isotope data reported in the literature paleoclimatic indices are identified 1 warmer indices include guembelitria columbiana and gallitellia and the globigerinoides cassigerinella dentoglobigerina altispira globigerina ciperoensis globorotalia s s groups 2 cooler indices include the globorotaloides catapsydrax and the globigerina s s groups and tenuitellids 3 warm temperate indices include the paragloborotalia siakensis paragloborotalia mayeri tenuitellinata angustiumbilicata and globoquadrina tripartita dentoglobigerina baroemoenensis sphaeroidinellopsis disjuncta praeglobigerinoides and globigerina ottnangiensis groups and 4 cool temperate indices include paragloborotalia nana paragloborotalia pseudocontinuosa globigerina aff praebulloides and the zeaglobigerina woodi group climatic curves were constructed for each hole the identified positive and negative peaks in the climatic curves are sometimes correlative from hole to hole general paleoclimatic trends can be summarized as follow cooling in subzone p21a late oligocene warming in subzone p21b to upper zone p22 late oligocene followed by a cooling and strong climatic instability from the uppermost zone p22 through zone n4 probably responsible for the discrepancies in distributions of some taxa reported in the literature across the oligocene miocene boundary and renewed warming from the upper part of zone n4b into zone n5 early miocene based on their abundance in the upwelling zones paragloborotalia kugleri globorotaloides hexagonus globorotaloides stainforthi and protentellids were identified as upwelling indices high abundances of these species associated with radiolarians diatoms and sponge spicules allowed identification of a major upwelling pulse in the lower part of zone n4

changes in the depth habitat of the oligocene planktic foraminifera dentoglobigerina venezuelana induced by thermocline deepening in the eastern equatorial pacific understanding planktic foraminiferal depth habitat along with consistent taxonomic concepts is key to accurate reconstruction of paleoceanographic records the oligocene pliocene long ranging and widely distributed species dentoglobigerina venezuelana lived in the mixed layer shallower during the early oligocene whereas the same species calcified at thermocline or subthermocline depths deeper during the late oligocene and miocene the exact timing of the species depth habitat change and its possible relationships with oligocene climate dynamics remain unknown here we reveal isotopic records of d venezuelana along with the paragloborotalia siakensis group a mixed layer dweller by using sediments at integrated ocean drilling program site u1334 in the eastern equatorial pacific throughout the oligocene a two step depth habitat change of d venezuelana is apparent 1 from upper to lower mixed layer 27 4 ma and 2 from lower mixed layer to thermocline depth 26 3 ma in addition the planktic foraminiferal faunal assemblage experienced a marked change from dominantly thermocline deeper species to abundant mixed layer shallower species suggesting that depth habitat shifts of d venezuelana were clearly related to thermocline deepening in the eastern equatorial pacific comparison of the first isotopic shift 27 4 ma at multiple sites u1334 u1333 and 1218 revealed a southward depth habitat change of d venezuelana within 200 kyr implying overall thermocline deepening with reduced steepness in the eastern equatorial pacific we consider that global warming conditions during the late oligocene likely caused thermocline deepening with upwelling decrease in the eastern equatorial pacific guiding d venezuelana to adapt to greater depths in the water column

shallow water tides in the northwest european shelf region from topex poseidon altimetry during recent years the accurate measurements from the topex poseidon satellite have improved global ocean tide models considerably however these global ocean tide models are still not accurate enough on the continental shelves for detailed oceanographic studies the need for increasing accuracy in shelf regions calls for inclusion of more than just semidiurnal and diurnal constituents in future global ocean tide models this is because a considerable part of the tidal variability on the shelves is caused by shallow water constituents one example is the m4 constituent which exceeds 50 cm at several locations on the northwest european shelf so far topex poseidon has not been considered for resolving these constituents mainly owing to its coarse ground track resolution reliable empirical estimates of several major shallow water constituents can be obtained from topex poseidon by combining along track and crossover observations estimates of the major shallow water constituents for the northwest european shelf m4 m6 and ms4 are presented in this study and compared with tide gauges and existing hydrodynamic models

effect of weathering on the compressibility and shear strength of a natural clay in situ seasonal changes expose soils to frequent wetting drying freezing thawing cycles such processes can favour and trigger shallow instabilities controlled by the weathering process this paper presents an experimental study carried out to investigate the effects of the weathering process caused by the wetting drying freezing thawing cycles on the compressibility and shear strength of a natural clay several specimens were trimmed from block samples of overconsolidated clays taken from a slope in south calabria italy specimens were subjected to wetting drying freezing thawing cycles of different durations and then tested with standard equipment oedometer and direct shear test results show that the wetting drying freezing thawing cycles caused a change in the initial microstructure that produced a decrease in the compression index and an increase in the swelling index moreover the direct shear test results show a decrease in the peak shear strength and demonstrate that a larger reduction occ

modelling the location of shallow landslides and their effects on landscape dynamics in large watersheds an application for northern new zealand in this study we propose a model to assess the location of shallow landslides and their impact on landscape development within a timeframe of years to decades processes that need to be incorporated in the model are reviewed then followed by the proposed modelling framework the capabilities of the model are explored through an application for a forested 17 km2 study catchment in northern new zealand for which digital elevation data are available with a grid resolution of 25 25 m the model predicts the spatial pattern of landslide susceptibility within the simulated catchment and subsequently applies a spatial algorithm for the redistribution of failed material by effectively changing the corresponding digital elevation data after each timestep on the basis of a scenario of triggering rainfall events relative landslide hazard and trajectories with runout criteria for failed slope material the resulting model will form a landslide module within the dynamic landscape evolution model lapsus the model forms a spatially explicit method to address the effects of shallow landslide erosion and sedimentation because digital elevation data are adapted between timesteps and on and off site effects over the years can be simulated in this way by visualization of the modelling results in a gis environment the shifting pattern of upslope and downslope in stability triggering of new landslides and the resulting slope retreat by soil material redistribution due to former mass movements can be simulated and assessed

atlantic paleogene biserial heterohelicid foraminifera and oxygen minima through most of the paleogene the planktonic foraminifera called biserial heterohelicids record the most depleted carbon isotope ratios among planktonic foraminiferal species they are interpreted to occupy an oxygen minimum habitat stronger interplanktonic carbon isotope contrasts and more enriched near surface carbon isotope values correspond to higher abundances of biserial heterohelicids this group appears to have preferred latitudes and times when the oxygen minimum was well developed biserial heterohelicid generic and specific diversity are directly related to the interplanktonic carbon isotope contrast minimal specific diversity characterizes the oligocene when interplanktonic and surface to bottom carbon isotope contrasts were consistently low diversity and abundance decreases were coeval with increased oceanic ventilation

neogene tectonostratigraphy and kinematics of calabrian basins implications for the geodynamics of the central mediterranean abstract a new structural model for the calabrian arc southern italy is presented based on a systematic analysis of basin kinematics combined with a review of the literature on basement structure three tectonic patterns can be distinguished a nw se trending oblique thrust zones determining a set of n130 trending segments b sw ne to e w trending thrust zones and c radial and concentric tensional fault systems in the southern tyrrhenian back arc area these faults combined with dome shaped uplift centres determine the actual arc patterns a and b can be regarded as the on shore representation of the calabrian accretionary wedge system the kinematics of various types of basins such as piggy back pull apart and complex oblique strike slip basins are connected to these patterns the patterns a and b can be linked to the middle miocene early pliocene development of oblique convergent crustal shear zones strike slip cycle whereas pattern c can be linked to the pleistocene collapse of the southern tyrrhenian basin and concentric uplift of the arc our structural model has considerable implications for the understanding of the kinematic evolution of the central mediterranean we propose a model in which the evolution is characterized by an alternation of the translation of the calabrian lithosphere element either to the southeast gravitationally or to the northeast compression combining a our analyses of basin evolution b the structural model and c some considerations concerning kinematics of the central mediterranean with the geodynamic mechanisms as proposed in literature we present a model which consists of a geodynamic cycle comprising the following three stages 1 a tension stage with back arc basin opening related to the diapiric inflow of asthenosphere material and roll back of the subducted ionian slab resulting in gravitational displacement of the calabrian element to the southeast 2 a transpression stage with oblique overthrusting towards the northeast upon the southern apennines and 3 a compression stage with ne sw compression due to oblique dextral shear along the north african margin plate rupture lithosphere split and back arc basin collapse

a three dimensional model of the m2 s2 n2 k1 and o1 tides in the celtic and irish seas abstract a three dimensional model using various parameterizations of eddy viscosity covering the celtic and irish sea region is used to examine the spatial distributions of the m2 s2 n2 k1 and o1 tidal elevations and phases computed cotidal charts and comparisons with observations from shore based and offshore gauges show good agreement comparisons are also made with a standard two dimensional model in shallow water regions the three dimensional model shows significantly less damping than the two dimensional model with an associated improvement in accuracy a detailed examination of differences between computed and observed tidal currents at over thirty locations having three or more current meters in the vertical show that the model can accurately reproduce the tidal current and its vertical profile in the eastern irish sea the region furthest from the model s open boundary good agreement with observations is obtained although in the deeper channel to the south of this the model over predicts current magnitude

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

three dimensional to two dimensional cross strata transition in the lower pleistocene catanzaro tidal strait transgressive succession southern italy sandstone tidal cross strata are the predominant sedimentary feature of strait fill stratigraphic successions however although widely described in numerous studies tidal strait fill two dimensional and three dimensional cross strata have rarely been reported to occur in discrete intervals which are laterally adjacent or vertically stacked and the meaning of this stratigraphic architecture has not yet been fully investigated understanding of the processes responsible for changes in the internal features of modern and ancient tidal bedforms is essential in order to predict lateral and vertical heterogeneities in analogous reservoir strata this facies based study aims to interpret the three dimensional to two dimensional cross strata transition observed in the lower pleistocene mixed siliciclastic bioclastic sandstone filling the catanzaro strait in southern italy during a continuous phase of tectonically driven marine transgression tidal cross strata disappear in the uppermost interval of the studied succession where mudstone strata prevail this stratigraphic trend is interpreted as the evidence of an important change in the tidal strait hydrodynamics due to a phase of relative sea level rise at the beginning of the transgression three dimensional tidal dunes migrated throughout the ca 3 to 4 km wide and ca 30 km long wnw ese oriented catanzaro strait due to strong tidal currents amplified through the seaway and flowing in semi diurnal phase opposition as the intermediate phase of transgression enlarged the seaway width the tidal current strength decreased as tidal water exchange occurred over a larger cross sectional area the progressive reduction of the bed shear stress modified three dimensional tidal dunes into an extensive two dimensional bedform field at the end of the transgression the further widening of the catanzaro strait into a ca 10 to 12 km wide marine passageway changed the tidally dominated strait into a non tidal open shelf the results of this research suggest the presence of a critical cross sectional area in the narrowest strait centre zone which controls the activation and deactivation of tidal current amplification along a marine seaway

evolution and biogeography of paleogene microperforate planktonic foraminifera abstract microperforations with a maximum diameter less than 1 m characterize some paleogene planktonic foraminifera and 5 microperforate groups are distinguished differences occur in pore density and wall textures as well as in the coiling mode these groups are unrelated phylogenetically and the microperforate wall represents a morphological character of convergence parvularugoglobigerina the earliest group with smooth surface and scattered microperforations evolved immediately after the k t boundary in many localities the globoconusa group is characterized by a heavily pustulate wall and relatively coarser pores of lower density derived from guembelitria members of this group occur in almost every marine sequence of the lower paleocene with no latitudinal preference but they tend to dominate shallow water assemblages in epicontinental seas and possibly are related to coastal upwelling together with its immediate ancestor woodringina and the evolutionary offshoots zeauvigerina and tubitextularia the biserial chiloguembelina contains the largest number of species falling into 4 subgroups as here recognized the chiloguembelinids dominated the early paleocene the high latitude middle eocene and the late eocene early oligocene the middle eocene guembelitria triseriata cassigerinelloita amekiensis lineage is defined by triserial to triserial pseudoplanispiral coiling and occurs mainly in marginal seas and over oceanic rises in southern oceans the tenuitellids the latest group first occur in the late eocene become common in the oligocene miocene and extend into the quaternary and modern oceans with a high frequency in high latitudes of the oligocene tenuitellids are considered to be cold water indicators

tidal modeling of an ancient tide dominated seaway part 2 the aptian lower greensand seaway of northwest europe abstract the cretaceous lower greensand deposits of southeastern england and northern france contain abundant evidence of diurnal once daily paleotides with tidal influence increasing into the late aptian the imperial college ocean model icom is used herein to determine the amplitude origin astronomical or co oscillating and characteristics diurnal or semidiurnal of the tides in the shallow marine lower greensand seaway where these sediments were deposited a global ocean paleotidal model of the aptian predicts very low tidal ranges microtidal in the proto central atlantic ocean and boreal ocean with higher tidal amplitudes especially of the diurnal constituents predicted in the northwestern neotethys ocean this suggests that the neotethys ocean was the only significant source of oceanic tides to the lower greensand seaway herein the results of the global ocean paleotidal model are used to supply boundary conditions to a higher resolution regional paleotidal model of the lower greensand seaway the regional paleotidal model shows that the tidal range of the lower greensand seaway is largely controlled by the width of the connections to the open ocean as sea levels rose during the aptian the oceanic connections widened resulting in reduced frictional damping of the oceanic tidal wave coupled with funneling shoaling and coriolis effects this led to tidal amplification sensitivity tests using a variety of paleogeography and paleobathymetry scenarios suggest that the model predictions are robust the global to regional scale paleotidal modeling presented here strongly suggests that there was a connection through france in the aube region of the paris basin from the neotethys ocean to southeastern england however there are no time equivalent deposits in this region to validate this suggestion it is herein argued that that this is due either to postdepositional erosion or to low sediment supply coupled with strong tidal currents sweeping the seafloor to exposed bedrock

on formulating two dimensional vertically integrated hydrodynamic numerical models with an enhanced representation of bed stress a convolution method is developed for computing the bottom stress in a vertically integrated hydrodynamic numerical model by this means the bottom stress is no longer related to the depth mean current as in a conventional vertically integrated model and an enhanced representation of the bottom stress is possible an enhanced vertically integrated model consequently the enhanced model can reproduce phase lags and differences in direction between bed stress and depth mean current which cannot be taken into account in conventional vertically integrated models a linear or quadratic frictional formulation can be used with the method idealized calculations of wind induced flow in a rectangular basin show that the bed stress computed by the convolution method is in excellent agreement with that derived using a full three dimensional model however significant differences in the bed stress between the three dimensional and conventional two dimensional model are evident also in this paper a method is developed for extracting current profiles from vertically integrated models current profiles extracted from the enhanced two dimensional model for a range of frictional effects are found to be in good agreement with those computed using a full three dimensional model

a landslide susceptibility model using the analytical hierarchy process method and multivariate statistics in perialpine slovenia abstract landslides cause damage to property and unfortunately pose a threat even to human lives good landslide susceptibility hazard and risk models could help mitigate or even avoid the unwanted consequences resulted from such hillslope mass movements for the purpose of landslide susceptibility assessment the study area in the central slovenia was divided to 78 365 slope units for which 24 statistical variables were calculated for the land use and vegetation data multi spectral high resolution images were merged using principal component analysis method and classified with an unsupervised classification using multivariate statistical analysis factor analysis the interactions between factors and landslide distribution were tested and the importance of individual factors for landslide occurrence was defined the results show that the slope the lithology the terrain roughness and the cover type play important roles in landslide susceptibility the importance of other spatial factors varies depending on the landslide type based on the statistical results several landslide susceptibility models were developed using the analytical hierarchy process method these models gave very different results with a prediction error ranging from 4 3 to 73 as a final result of the research the weights of important spatial factors from the best models were derived with the ahp method using probability measures potentially hazardous areas were located in relation to population and road distribution and hazard classes were assessed

susceptibility zoning of shallow landslides in fine grained soils by statistical methods abstract the paper proposes a methodology in two successive steps to zone the susceptibility to shallow landslides in fine grained soils by means of statistical methods the first step of the methodology aiming at defining calibrating and validating the statistical analysis ends with a landslide susceptibility computational map the second step of the methodology is employed to produce a susceptibility map for zoning purposes this structured methodology arises from the need to distinguish at any given scale of analysis between the spatial discretization needed to perform the statistical computations terrain computational units and terrain units useful for zoning purposes terrain zoning units the applicability of the proposed methodology is tested at two different scales 1 25 000 and 1 5000 in two areas of southern italy the test area for the larger scale being a portion of the test area used for the analysis at the smaller scale this allows for the generalization of the obtained results through the comparison for the same phenomena in the same geo environmental context of the predisposing factors at two scales of analysis in both analyses the relevant variables for the susceptibility assessment are elevation zone slope gradient slope curvature and geology in the analysis at large scale also the weathered rock thickness available only at this scale assumes a relevant role in both cases the aggregation of multiple terrain computational units tcu into a larger terrain zoning unit tzu works best when focal statistic techniques are used with a characteristic dimension of the area of influence equal to 16 tcus

a near field sea level record of east antarctic ice sheet instability from 32 to 27 myr 1 fossil facies and isotope analyses of an early high paleolatitude 55 s section suggests a highly unstable east antarctic ice sheet from 32 to 27 myr the waxing and waning of this ice sheet from 140 to 40 of its present volume caused sea level changes of 25 m ranging from 30 to 50 m related to periodic glacial 100 000 to 200 000 years and shorter interglacial events the near field gippsland sea level gsl curve shares many similarities to the far field new jersey sea level njsl estimates however there are possible resolution errors due to biochronology taphonomy and paleodepth estimates and the relative lack of lowstand deposits in njsl that prevent detailed correlations with gsl nevertheless the lateral variations in sea level between the gsl section and njsl record that suggest ocean siphoning and antisiphoning may have propagated synchronous yet variable sea levels

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

reconstruction of oceanic circulation patterns in the tropical pacific across the early middle miocene boundary as inferred from radiolarian assemblages abstract although there have been attempts to infer neogene oceanic circulation patterns in the tropical pacific on the basis of multiple marine proxies oceanic circulation patterns across the early middle miocene boundary are still poorly understood despite paleoclimate having significantly changed during this interval in this study we reconstruct the changes in tropical oceanic circulation patterns in the pacific across the early middle miocene boundary based on radiolarian assemblages obtained at integrated ocean drilling program site u1335 in the eastern tropical pacific the radiolarian upwelling taxa increased during four intervals 18 4 18 1 ma 16 9 15 7 ma 15 2 14 6 ma 14 2 13 4 ma radiolarian temperature index rti was calculated using the relative abundances of the warm water cluster b1 and cool water taxa cluster b2 in order to evaluate relative temperature fluctuations of the surface water the sea surface temperature index was relatively high from 16 8 to 16 0 ma and gradually decreased from 16 0 to 14 6 ma subsequently the temperature index decreased stepwise at 13 9 and 13 4 ma and became relatively low from 13 4 to 12 7 ma comparison of the rti record in the eastern tropical pacific to the climatic index based on the benthic foraminiferal 18o record shows that variability in the two records follows a roughly similar trend from the early to the middle miocene however the sea surface temperature record does not indicate a sharp increase in warmth in the eastern tropical pacific during the mid miocene climatic optimum 1 mmco 1 as suggested by the benthic isotopic record this is likely because of increased upwelling of cool nutrient rich water at this time beginning in the latest early miocene 17 ma radiolarian assemblages were dominated by different taxa in the eastern and western tropical pacific this pattern is interpreted as indicating a shallower thermocline in the east and a deeper thermocline in the west based on the relative abundance of the upwelling taxa there is an overall increasing trend in this difference since the latest early miocene we tie these events to the effective closure of the indo pacific seaway and the development of a substantial western pacific warm pool along with the development of a strong equatorial undercurrent

on extracting tidal current profiles from vertically integrated two dimensional hydrodynamic models a numerically accurate and computationally efficient method is developed for extracting tidal current profiles from vertically integrated two dimensional models the method can incorporate an arbitrary profile of eddy viscosity and determines tidal current profiles satisfying a no slip condition at the sea bed comparisons with observations and current profiles computed with full three dimensional models confirm the accuracy of the method bottom boundary layer thicknesses determined from these current profiles clearly show regions of the european continental shelf where the bottom boundary layer extends to the sea surface the boundary between these regions and other areas where the bottom layer is less than the water depth corresponds quite closely to the known position of tidal fronts

a three dimensional model of the m4 tide in the irish sea the importance of open boundary conditions and influence of wind a fully nonlinear three dimensional hydrodynamic model of the irish sea is used to examine the processes determining the spatial variability of the m4 tide in the irish sea the model is based upon a mixed spectral finite difference approach with an expansion of functions in the vertical yielding a continuous current profile and a finite difference grid in the horizontal the model has a sufficiently fine grid to enable the nonlinear advective terms to be resolved in their finite difference form and the spatial variability of the m4 tide to be represented computed m4 elevations and currents determined using a radiation open boundary condition with both m2 mid m4 elevation and current input and a flow dependent viscosity are found to be in satisfactory agreement with observations considering the limited grid resolution of the model and the level of noise in the m4 tide as a percentage of the signal is much higher than for m2 this agreement is good enough to establish the credibility of using the model to examine the processes influencing the m4 tide which are discussed in detail the importance of an m4 current input to the radiation condition and the difficulty of using an elevation specified open boundary condition to reproduce the m4 tide in this region are considered in some detail the nonlinear advective terms are shown to have a limited local influence namely around headlands in generating the m4 tide the influence of wind effects upon m4 tidal currents particularly through the nonlinear term associated with a time dependent eddy viscosity is examined and shown to produce a significant increase in the m4 near surface tidal current and a modification of the current profile in essence the change of the m4 tidal current by meteorological effects will give rise to noise in any observed m4 current due to the random nature of the wind fields

the evolutionary history of size variation of planktic foraminiferal assemblages in the cenozoic abstract the iterative evolutionary radiation of planktic foraminifers is a well documented macroevolutionary process here we document the accompanying size changes in entire planktic foraminiferal assemblages for the past 70 my and their relationship to paleoenvironmental changes after the size decrease at the cretaceous paleogene k p boundary high latitude assemblages remained consistently small size evolution in low latitudes can be divided into three major phases the first is characterized by dwarfs 65 42 ma the second shows moderate size fluctuations 42 14 ma and in the third phase planktic foraminifers have grown to the unprecedented sizes observed today our analyses of size variability with paleoproxy records indicate that periods of size increase coincided with phases of global cooling eocene and neogene these periods were characterized by enhanced latitudinal and vertical temperature gradients in the oceans and high diversity polytaxy in the paleocene and during the oligocene the observed minor size changes of the largely low diversity oligotaxic assemblages seem to correlate with productivity changes however polytaxy per se was not responsible for larger test sizes

combining spatial data in landslide reactivation susceptibility mapping a likelihood ratio based approach in w belgium a key issue in landslide susceptibility mapping concerns the relevance of the spatial data combination used in the prediction various combinations of high resolution predictor variables and possibilities of selecting them from a larger dataset are analysed the scarp reactivation of several landslides in a hilly region of w belgium is investigated at the pixel scale the susceptibility modelling uses the reactivated scarp segments as the dependent variable and 13 factors at a 2 m resolution related to topography hydrology land use and lithology as potential independent variables the modelling uses a likelihood ratio approach based on the comparison for each independent variable between two empirical distribution functions edfs respectively for the reactivated and non reactivated areas it uses these edfs as favourability values to build membership values and combine them with a fuzzy gamma operator five different data combinations are tested and compared by analysing the prediction rate curves obtained by cross validation the geomorphological value of the resulting susceptibility maps is also discussed this research shows relevant results for predicting the susceptibility to scarp reactivation we highlight the need for testing several data combinations and underline that combining quantitative criteria with expert opinion is an asset for reliable predictions

oligocene miocene basin evolution in se anatolia turkey constraints on the closure of the eastern tethys gateway the oligocene miocene was a time characterized by major climate changes as well as changing plate configurations the middle miocene climate transition 17 to 11 ma may even have been triggered by a plate tectonic event the closure of the eastern tethys gateway the marine connection between the mediterranean and indian ocean to address this idea we focus on the evolution of oligocene and miocene foreland basins in the southernmost part of turkey the most likely candidates to have formed this gateway in addition we take the geodynamic evol ution of the arabian eurasian collision into account the musand elazog u basins located to the north of the bitlis zagros suture zone were most likely connected during the oligocene the deepening of both basins is biostratigraphically dated by us to occur during the rupelian early oligocene deep marine conditions between 350 and 750 m prevailed until the chattian late oligocene when the basins shoaled rapidly to subtidal intertidal environment in tropical to subtropical conditions as indicated by the macro fossil assemblages we conclude that the emergence of this basin during the chattian severely restricted the marine connection between an eastern indian ocean and western mediterranean marine domain if a connection persisted it was likely located south of the bitlis zagros suture zone the kahramanmarasbasin located on the northern arabian promontory south of the bitlis zagros suture zone was a foreland basin during the middle and late miocene possibly linked to the hatay basin to the west and the lice basin to the east our data indicates that this fore land basin experienced shallow marine conditions during the langhian followed by a rapid dee pening during langhian serravallian and prevailing deep marine conditions between 350 and 750 m until the early tortonian we have dated the youngest sediments underneath a subduc tion related thrust at c 11 ma and suggest that this corresponds to the end of underthrusting in the kahramanmarasregion i e the end of subduction of arabia this age coincides in time with the onset of eastern anatolian volcanism uplift of the east anatolian accretionary complex and the onset of the north and east anatolian fault zones accommodating westward escape tec tonics of anatolia after c 11 ma the foreland basin south of the bitlis formed not or no longer a deep marine connection along the northern margin of arabia between the mediterranean sea and the indian ocean we finally conclude that a causal link between gateway closure and global climate change to a cooler mode recorded in the mi3b event d 18 o increase dated at 13 82 ma cannot be supported

a comparison of statistical and deterministic methods for shallow landslide susceptibility zoning in clayey soils abstract shallow landslides are widespread in different geological contexts and generally occur as multiple events over large areas when these phenomena involve fine grained soils they may cause serious consequences in terms of environmental and property damages and thus their spatial forecasting becomes a relevant issue for land use planning and design purposes the existing literature provides several methods for landslide susceptibility assessment categorized in qualitative and quantitative methods when dealing with analyses at large scale 1 5000 quantitative methods are generally preferred in this paper landslide susceptibility maps are produced for a study area prone to shallow landsliding located in catanzaro southern italy to this aim two quantitative methods are implemented the statistical information value method and the deterministic trigrs model the two approaches are compared by means of two indicators of the grade of correctness of the landslide susceptibility maps the area under curve of the roc curve auc and the overestimation index oi the results of the analyses in terms of auc values demonstrate the effectiveness and consistency of both methods in performing the susceptibility mapping of the study area when the oi values are considered the results provided by the deterministic model are slightly better than the ones resulting from the statistical analysis this does not come as a surprise for the case study at hand and it can be ascribed to the availability within the study area of a reliable database of soil properties and an in depth knowledge of the behaviour of the considered landslides

verification of landslide susceptibility mapping a case study a methodology is proposed for mapping susceptibility to landsliding and validating the results heavy rains in late 1996 and early 1997 led to a large number of landslids in the rute sector cordoba southern spain where landslide susceptibility mapping had previously been carried out using a matrix method developed with a geographical information system gis analysis of the distribution of the new landslides or reactivated earlier ones enabled the methodology to be validated by calculating association coefficients and determining the closeness of the match between subsequent field evidence and the previously defined susceptibility levels from the data obtained it can be concluded that the susceptibility mapping effectively explained the spatial distribution of landslides thus providing valuable information on stability conditions over a widespread area copyright 1999 john wiley sons ltd

a numerical model study of parameters influencing tidal currents in the irish sea the mathematical formulation of a mixed finite difference modal three dimensional tidal model of the irish sea using quadratic bottom friction is briefly presented by using an expansion of modes in the vertical a continuous current profile from sea surface to seabed can be computed and accurate comparisons made with tidal currents measured at a range of positions throughout the water column the sensitivity of current profiles to various eddy viscosity formulations and coefficients of bottom friction are examined in detail also the influence of open boundary conditions and water depths upon computed tidal elevations and currents is examined in common with other earlier published calculations initial results show that with previous formulations of eddy viscosity and friction an accurate distribution of sea surface elevations is accompanied with computed currents which exceed observations by the order of 20 cm s 1 however results from the sensitivity study presented here show that elevations and currents above the bottom boundary in good agreement with observations can be obtained with alternative formulations of viscosity and other friction coefficients together with current input to the radiation condition however computed near bed currents are still larger than those observed although a slight increase in water depth and bottom friction coefficients corrects this calculations clearly show that the computation of near bed currents subject to the constraints of obtaining accurate elevation and current distributions is the most sensitive test of the model excellent agreement between computed and observed currents and elevations was obtained in a final series of calculations using appropriate parameterizations of eddy viscosity and bottom friction

on improving the bed stress formulation in storm surge models a method of improving the representation of bottom stress in storm surge models an enhanced bed stress model is tested using a fine mesh model of the celtic and irish seas and is compared with results from a conventional two dimensional model the approach uses a convolution method to determine the bed stress rather than relating it directly to the depth mean current as in a conventional storm surge model for the region considered comparisons of surge elevations computed with both models and observations show only a slight improvement of surge elevation in the near coastal region with the enhanced bed stress model however spatial distributions of bed stresses from the two models do exhibit significant differences which are important in considering sediment movement paths during major storms the magnitude and direction of the bed stress vectors computed from the enhanced bed stress model are in excellent agreement with calculations using a full three dimensional model of the area this suggests that the enhanced bed stress model can compute a bed stress that is not significantly different from that in a full three dimensional model at a fraction of the computational cost

the response of the irish sea to boundary and wind forcing results from a three dimensional hydrodynamic model a three dimensional nonlinear hydrodynamic model of the irish sea is used to examine the response of the region to forcing along its open boundary and wind stress over the area frictional dissipation at the bed is parameterized with a quadratic law of bottom friction which can take account of enhanced frictional effects due to wind wave current interaction a standard finite difference grid is used in the horizontal with an expansion of functions through the vertical giving a continuous current profile from sea surface to seabed the model has a grid resolution of the order of 3 km and hence can resolve some features of the nearshore region the model is forced with m2 tidal input along its open boundary and time invariant wind fields corresponding initially to spatially uniform northerly and westerly wind stresses of 1 n m2 and subsequently to a west east gradient wind changing from 1 n m2 to 1 n m2 going from west to east and a north south gradient wind changing from 1 n m2 to 1 n m2 going from north to south the response to open boundary forcing through both elevations and currents is also examined and the influence of the effects of enhanced bottom friction due to wind waves is also briefly considered