first independent graz lunar gravity model derived from grail abstract the twin satellite mission gravity recovery and interior laboratory grail aims to recover the lunar gravity field by means of ka band ranging observations in order to exploit the potential of the inter satellite range variations absolute position information of the two probes is required hitherto the graz lunar gravity field models grazlgm relied on the official science orbit products provided by nasa in this contribution we present for the first time a completely independent graz lunar gravity model based on primary mission data the models are resolved up to spherical harmonic degree and order 420 the orbits of the two probes are determined using variational equations following a batch least squares differential adjustment process implemented in the in house developed software package orca orbit re construction application these orbits are based on s band radiometric tracking data collected by the deep space network dsn and are used for the independent grail gravity field recovery to reveal a highly accurate lunar gravity field an integral equation approach using short orbital arcs is adopted to process the ka band data where no regularization or kaula constraint is applied the correlation of gravity with lunar topography as well as the bouguer spectrum of our solutions is comparable to the models officially released by the grail science team

an improved lunar gravity field model from selene and historical tracking data revealing the farside gravity features 1 a new spherical harmonic solution of the lunar gravity field to degree and order 100 called sgm100h has been developed using historical tracking data and 14 2 months of selene tracking data from 20 october 2007 to 26 december 2008 plus 30 january 2009 the latter includes all usable 4 way doppler data collected which allowed direct observations of the farside gravity field for the first time the new model successfully reveals farside features in free air gravity anomalies which are characterized by ring shaped structures for large impact basins and negative spots for large craters sgm100h produces a correlation with selene derived topography as high as about 0 9 through degree 70 comparison between sgm100h and lp100k one of the pre selene models shows that the large gravity errors which existed in lp100k are drastically reduced and the asymmetric error distribution between the nearside and the farside almost disappears the gravity anomaly errors predicted from the error covariance through degree and order 100 are 26 mgal and 35 mgal for the nearside and the farside respectively owing to the 4 way doppler measurements the gravity coefficients below degree and order 70 are now determined by real observations with contribution factors larger than 80 percent with the selene farside data coverage it is possible to estimate the gravity field to degree and order 70 without applying any a priori constraint or regularization sgm100h can be used for global geophysical interpretation through degree and order 70

evaluation of a distributed catchment scale water balance model the validity of some of the simplifying assumptions in a conceptual water balance model is investigated by comparing simulation results from the conceptual model with simulation results from a three dimensional physically based numerical model and with field observations we examine in particular assumptions and simplifications related to water table dynamics vertical soil moisture and pressure head distributions and subsurface flow contributions to stream discharge the conceptual model relies on a topographic index to predict saturation excess runoff and on philip s infiltration equation to predict infiltration excess runoff the numerical model solves the three dimensional richards equation describing flow in variably saturated porous media and handles seepage face boundaries infiltration excess and saturation excess runoff production and soil driven and atmosphere driven surface fluxes the study catchments a 7 2 km2 catchment and a 0 64 km2 subcatchment are located in the north appalachian ridge and valley region of eastern pennsylvania hydrologic data collected during the machydro 90 field experiment are used to calibrate the models and to evaluate simulation results it is found that water table dynamics as predicted by the conceptual model are close to the observations in a shallow water well and therefore that a linear relationship between a topographic index and the local water table depth is found to be a reasonable assumption for catchment scale modeling however the hydraulic equilibrium assumption is not valid for the upper 100 cm layer of the unsaturated zone and a conceptual model that incorporates a root zone is suggested furthermore theoretical subsurface flow characteristics from the conceptual model are found to be different from field observations numerical simulation results and theoretical baseflow recession characteristics based on boussinesq s groundwater equation

infiltration on sloping terrain and its role on runoff generation and slope stability abstract a modified green and ampt model is formulated to quantify infiltration on sloping terrain underlain by homogeneous soil wetted by surficial water application this paper s theory for quantifying infiltration relies on the mathematical statement of the coupled partial differential equations pdes governing infiltration and runoff these pdes are solved by employing an explicit finite difference numerical method that yields the infiltration the infiltration rate the depth to the wetting front the rate of runoff and the depth of runoff everywhere on the slope during external wetting data inputs consist of a water application rate or the rainfall hyetograph of a storm of arbitrary duration soil hydraulic characteristics and antecedent moisture and the slope s hydraulic and geometric characteristics the presented theory predicts the effect an advancing wetting front has on slope stability with respect to translational sliding this paper s theory also develops the 1d pde governing suspended sediment transport and slope degradation caused by runoff influenced by infiltration three examples illustrate the application of the developed theory to calculate infiltration and runoff on a slope and their role on the stability of cohesive and cohesionless soils forming sloping terrain

soils slopes and source rocks application of a soil chemistry model to nutrient delivery to rift lakes abstract the topographic evolution of rift basins may be critical to the deposition of lacustrine source rocks such as the organic rich lower cretaceous shales of the south atlantic margin soils have been proposed as a key link between topography and source rock deposition by providing nutrients for the algae growth in rift lakes decreasing topographic relief from active rift to late rift has several effects on soils soils become thicker and finer erosion of dead surface and soil organic matter decreases and the fractionation of precipitation between runoff and infiltration may favor increased infiltration this hypothesis is tested by application of century a complex box model that simulates transfer of nutrients within soil pools the model is first applied to a rainforest soil with several parameters individually varied infiltration experiments show that the concentrations of c n and p in groundwater decrease rapidly as infiltration decreases whether due to increased slope or to decreased precipitation increased erosion of surface plant litter and topsoil results in substantially decreased nutrient concentrations in groundwater increased sand content in soil causes an increase in nutrient concentration we integrate these variables in analyzing topographic swathes from the rio grande rift comparing the southern part of the rift where topography is relatively old and reduced to the northern rift c and p concentrations in groundwater increase as slope gradient decreases resulting in substantially larger c and p concentrations in groundwater in the southern rift than the northern rift nitrogen concentrations in groundwater depends on whether infiltration varies as a function of slope gradient in experiments where the fraction of infiltrated precipitation decreased with increasing slope n concentrations was also substantially higher in the southern rift but in experiments where that fraction was held constant n concentrations was lower in the southern rift these simulations demonstrate that evolving topography during rift development can significantly influence nutrient concentrations in groundwater and if these nutrients flow into rift lakes and stimulate organic productivity account for the deposition of rich oil prone source rocks in late rift stages

hillslope run off thresholds with shrink swell clay soils irrigation experiments on 12 instrumented field plots were used to assess the impact of dynamic soil crack networks on infiltration and run off during applications of intensity similar to a heavy rainstorm water was seen being preferentially delivered within the soil profile however run off was not observed until soil water content of the profile reached field capacity and the apertures of surface connected cracks had closed 60 electrical resistivity measurements suggested that subsurface cracks persisted and enhanced lateral transport even in wet conditions likewise single ring infiltration measurements taken before and after irrigation indicated that infiltration remained an important component of the water budget at high soil water content values despite apparent surface sealing overall although the wetting and sealing of the soil profile showed considerable complexity an emergent property at the hillslope scale was observed all of the plots demonstrated a strikingly similar threshold run off response to the cumulative precipitation amount copyright 2014 john wiley sons ltd

moving multi front mmf a generalized green ampt approach for vertical unsaturated flows abstract a moving multi front mmf method is developed and tested for solving the richards equation governing unsaturated flow in vertical homogeneous porous columns the mmf model is a gridless method it can be viewed as a generalization of the green ampt piston flow approach which models flow as a single abrupt moving front separating saturated and dry regions during infiltration the mmf model further generalizes this concept using a parametrization of unsaturated water retention and conductivity pressure curves it reduces the richards pde to an ode system governing m moving front positions different tests are developed to validate this approach for 1d transient downwards upwards flows submitted to constant and time varying pressure boundary conditions they include i infiltration to deep water tables ii infiltration to shallow water tables iii capillary rise from fixed water tables iv gradual water table rise partially saturated column with evolving pressure condition at bottom the mmf results are compared favorably to finely discretized fixed grid solutions of richards pde analyses of error and accuracy show satisfactory results in terms of water content profiles and boundary fluxes e g infiltration rate

the geochemistry and petrogenesis of ophiolitic volcanic rocks from lac de l est thetford mines complex quebec canada the cambro ordovician age thetford mines complex from the quebec appalachians canada preserves a remarkably complete section of ophiolites at lac de l est where mafic volcanics overlie a plutonic mafic ultramafic plate the basaltic volcanics consist of a lower unit representing the extrusive component of the ophiolite assemblage and an upper unit whose petrogenetic and tectonic relationships with the ophiolitic volcanics are problematic the lower unit ophiolitic volcanics include high and low tio2 basalts the upper unit volcanics of which the basal 80 m was sampled are low tio2 basalts fractional crystallization was important in the evolution of high tio2 lower unit magmas but played only a minor role in the formation of other magmas partial melting processes were dominant or much more important than fractional crystallization in controlling the composition of other magmas the parental magmas of the high tio2 lower unit basalts were partial melts of undepleted mantle whereas the low tio2

spatial variability of saturated hydraulic conductivity and measurement based intensity duration thresholds for slope stability santa ynez valley ca abstract shallow landslides are commonly triggered by positive pore fluid pressures generated at the soil bedrock interface and are linked to heavy rainfall in this study in situ measurements of saturated hydraulic conductivity ksat were performed at three historic landslide sites to determine its variability and implications on predicting rainfall rate thresholds for shallow landslides in the santa ynez valley ca falling head tests were performed in the soil column and at the soil bedrock interface to estimate ksat it was found that overlying soils from the a and b horizons exhibited higher infiltration rates ranging from 37 to 138 mm h and 24 to 77 mm h respectively whereas the failure plane coincident with the soil bedrock interface exhibited ksat values ranging from 4 to 33 mm h below the soil bedrock interface ksat ranged from 5 to 123 mm h signifying a pattern of fast slow fast infiltration measurements of grain size distributions and bulk density do not provide insight into the cause of low conductivity at the soil bedrock interface rather field observations suggest that the infilling of fractures and pore spaces with fine grained particles and caliche are a possible cause of the low conductivity layer measurements of soil mechanical and hydrologic properties were used in a finite slope stability model as well as a simple 1 d flow model to predict intensity duration i d thresholds for shallow landsliding in this area results of this analysis indicate rainfall intensities 20 30 mm h that are sustained for 2 4 h are capable of triggering widespread shallow landsliding this study also suggests that the variability in ksat at the failure plane can produce significant changes in i d thresholds for failure and is an important factor in predicting slope stability over any spatial scale

kinematics and rheology of a major landslide based on signal analysis a detailed geodetic record which is over 23 years old and describes the kinematics of the mandria or left bank upstream landslide a major deep seated landslide close to the polyphyton dam greece was analysed on the basis of advanced signal analysis techniques without any geotechnical constraints it was found that all points share the same pattern of displacement which characterises both short and longer records the overall behaviour of the landslide can be described as viscoelastic and viscous or elastoviscous with multi annual periodic effects superimposed on the creep as the results of spectral analysis indicate the landslide seems insensitive to seasonal variations of precipitation and to annual fluctuations of the reservoir level although the first filling of the reservoir is likely to have had an important role in its movement there is a lack of subsurface information but the available data indicate that the landslide corresponds to a rigid mass dominated by brittle behaviour and int

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

delineation of subsurface variability in clay rich landslides through spectral induced polarization imaging and electromagnetic methods abstract although commonly triggered by heavy or long lasting precipitation events landslides in clay rich formations are hardly predictable as their triggering mechanisms are still not fully understood hence detailed information about the internal structure of landslides with high spatial resolution is fundamental for an improved understanding of triggering mechanisms and management in this context electrical resistivity tomography ert is a well established method used for the delineation of lithological interfaces in landslides and changes in water content however the quantitative interpretation of the ert images can be challenging particularly for clay rich landslides considering that the electrical signatures are dominated by the variations in the clay fraction rather than saturation moreover large scale investigations also demand the development of faster surveying techniques hence in this study we discuss the combined investigation of a landslide with low induction number electromagnetic emi mapping and induced polarization ip imaging we investigate the application of such methods to assess subsurface variability across different scales near surface emi mapping and their correlation with geomorphological data whereas ip images are used to investigate the extension at depth from the shallow structures measurements are performed at a shallow clay rich landslide in lower austria austria characterized by lithological structures of the flysch and gresten klippen zone with both formations known to be highly susceptible to landsliding the interpretation of the imaging results for data collected along 15 profiles is performed using separately acquired hydrogeological and geotechnical data we observe a relationship between the electrical properties and geotechnical parameters which permits to delineate areas associated to different weathering stages controlling the groundwater flow moreover spectral induced polarization sip data collected along one transect shows sensitivity to changes in textural composition such as the fraction of clay minerals the study shows the suitability of an integrated investigation with emi mapping and ip imaging in combination with extensive geotechnical data for an improved characterization of subsurface variability and thus understanding of clay rich landslides

solution to the kinematic wave approach to overland flow routing with rainfall excess given by philip s equation a solution to the kinematic wave equations for overland flow routing where the lateral inflow term is determined from a constant rainfall rate and the infiltration model of philip is presented the solution utilizes the method of characteristics and while it is not completely analytical it is reduced to a simple numerical procedure which does not require the use of finite differences the analysis presented deals with both the rising and falling stages example calculations water surface profiles and hydrographs are shown

relationship between rain and or meltwater pore water pressure and displacement of a reactivated landslide abstract in order to clarify the relationship between rain and or meltwater mr pore water pressure and landslide displacement continuous monitorings were conducted at a reactivated landslide comprised mainly of weathered mudstone of tertiary in age an exponential relationship was found between the total amount of mr at each event and the amount of pore water pressure increment integrated by time impulse of pore water pressure in addition as the total mr increased the difference between the minimum and maximum values of pore water pressure for each event fluctuation range of pore water pressure also increased but the intensity of mr had little effect on the fluctuation range of pore water pressure the correlation coefficient for the fluctuation range of pore water pressure and cumulative landslide displacement and that for the impulse of pore water pressure and cumulative displacement were similar but were only 0 57 to 0 66 on the other hand the correlation coefficient for the total mr and cumulative landslide displacement was large 0 65 0 69 cumulative landslide displacement was very highly correlated with effective mr which shows the estimated water content in the ground for a half life period of 4 days and correlation coefficients were 0 89 0 92 thus the displacement characteristics of this reactivated landslide which has a long history of landsliding can be explained using the hydrological factor of water content rather than the hydraulic characteristics of pore water pressure

power series solution for falling head ponded infiltration with evaporation 1 assumptions for many of the derived analytical infiltration models are either a constant infiltration rate or a constant head at the soil surface for many realistic infiltration situations a falling head boundary condition is more appropriate philip showed that both the wetting profiles and the cumulated infiltration in one dimensional infiltration into homogenous soil with constant head at the upper boundary can be written as a power series in t presently it is shown that a power series solution can be applied for falling head infiltration with evaporation when comparing with the constant head solution the falling head solution differs only from the second term i e the sorptivity remains unchanged a result which can be applied to falling head infiltrometer technique the effect of a constant evaporation rate in the falling head scenario appears from the third term in the presented numerical examples the retention model by van genuchten and the hydraulic conductivity model by mualem are applied by comparing the wetting profiles obtained with a fem solution it is shown that the discrepancies between the models are very small also the estimation of the time at which the pond is emptied is concordant the infiltration model is compared with a model by parlange and colleagues and a simple infiltrometer method for determining the saturated hydraulic conductivity is proposed

tectonic conditioning revealed by seismic refraction facilitates deep seated landslides in the western escarpment of the main ethiopian rift abstract landslide is a geo hazard phenomenon that has been taking lives and causing severe property damages all over the world mostly in mountainous areas the main ethiopian rift has a unique tectonic setting with complex geological and geomorphological features coupled with continuously deteriorating environmental conditions which made its escarpments vulnerable for landslides the study area is located near the debre sina town within the yizaba wein locality which has been severely affected by frequent landslide problems this work was carried out using a multidisciplinary approach based on geological geomorphological kinematic analysis and geophysical survey seismic refraction investigations were carried out along the yizaba wein landslide main scarp to determine the depth to the bedrock and to the failure plane to assess the stability of the slope to locate possible structural features and to identify the extent of recent landslide activity and to study the subsurface situation the seismic measurements were made along three nearly orthogonal survey lines in the recently affected area a high resolution 2d p wave survey was conducted using a 24 channel seismic unit the seismic refraction results revealed four layers of geomaterials with distinct physical characteristics that contained a subsurface landslide anomaly within the layers the layers were interpreted according to the major lithological units from top to bottom i clay loosely cemented colluvial sediments and highly weathered agglomeratic basalt ii highly to moderately fractured porphyritic basalt ignimbrite volcanic ash and rhyolite trachyte iii moderately to slightly fractured ignimbrite rhyolite trachyte and basalt and iv very strong massive fresh rock bedrock faults and weak zones have also been identified in the bedrock based on the abundance of fractures and subsidiary faults resulting from damage of rocks and change of lithology due to variable fault rock formation strongly influencing the wavefield distribution which usually causes a local decrease of the velocity value the main findings show that the landslide in the yizaba wein locality was caused by its complex geological structural setting and downslope movement of the underlying pyroclastic sediment facilitated by heavy rainfall considering the similar geological and tectonic settings similar mechanisms can be assumed for other landslides along the rift margins and associated highlands of ethiopia

falling head ponded infiltration in the nonlinear limit the green and ampt infiltration solution represents only an extreme example of behavior within a larger class of very nonlinear delta function diffusivity soils the mathematical analysis of these soils is greatly simplified by the existence of a sharp wetting front below the soil surface solutions for more realistic delta function soil models have recently been presented for infiltration under surface saturation without ponding after general formulation of the problem solutions for a full suite of delta function soils are derived for ponded surface water depleted by infiltration exact expressions for the cumulative infiltration as a function of time or the drainage time as a function of the initial ponded depth may take implicit or parametric forms and are supplemented by simple asymptotic expressions valid for small times and small and large initial ponded depths as with surface saturation without ponding the green ampt model overestimates the effect of the soil hydraulic conductivity at the opposing extreme a low conductivity model is identified that also takes a very simple mathematical form and appears to be more accurate than the green ampt model for larger ponded depths between these two the nonlinear limit of gardner s soil is recommended as a physically valid first approximation relative discrepancies between different soil models are observed to reach a maximum for intermediate values of the dimensionless initial ponded depth and in general are smaller than for surface saturation without ponding

rainfall ground water flow and seasonal movement at minor creek landslide northwestern california physical interpretation of empirical relations simple ground water flow analyses can clarify complex empirical relations between rainfall and landslide motion here we present detailed data on rainfall ground water flow and repetitive seasonal motion that occurred from 1982 to 1985 at minor creek landslide in northwestern california and we interpret these data in the context of physically based theories we find that landslide motion is closely regulated by the direction and magnitude of near surface hydraulic gradients and by waves of pore pressure caused by intermittent rainfall diffusive propagation of pore pressure waves accompanies downward ground water flow along nearly vertical hydraulic gradients that exist in most of the landslide field data combined with a pore pressure diffusion analysis show that single rainstorms typically produce short period waves that attenuate before reaching the landslide base in contrast seasonal rainfall cycles produce long period waves that modify basal pore pressures but only after time lags that range from weeks to months such tune lags can depend on antecedent moisture storage and can explain variable delays between the onset of the wet season and seasonal landslide motion limit equilibrium analysis shows that when seasonal pressure waves reach the landslide base they establish a critical distribution of effective stress that delicately triggers landslide motion the critical effective stress balance is extremely sensitive to the direction and magnitude of hydraulic gradients although pervasively downward gradients instigate seasonal motion we infer from theory and limited data that ground water also may circulate locally in near surface cells the circulation can further reduce the landslide s frictional strength particularly in areas of nearly horizontal ground water flow that occur beneath steep faces of hummocks hummocky topography that results from slope instability may therefore cause ground water flow that perpetuates instability

analysis of physical testing of rainfall induced soil slope failures rainfall is a significant factor that triggers slope failures around the world this paper reports a series of physical tests which were conducted to simulate rain induced slope failures the experiments dealt with two scenarios including 1 rainwater infiltration into the slope and 2 slope failures induced by artificial rainfall with different initial conditions slope deformation and slope failures were observed and possible mechanisms were interpreted based on the experimental results the results confirm the hypothesis that pore water pressure and water content in a loose soil slope change rapidly and that water infiltration into cracks in the slope has a great impact on landslide development the observed slope failures can be divided into three types overall sliding failure partial sliding failure and flow slide the effect of slope gradient rainfall intensity and distribution of initial suction on the slope deformation and failure process are also summarized for possible applications under the similar conditions

a 70th degree lunar gravity model glgm 2 from clementine and other tracking data a spherical harmonic model of the lunar gravity field complete to degree and order 70 has been developed from s band doppler tracking data from the clementine mission as well as historical tracking data from lunar orbiters 1 5 and the apollo 15 and 16 subsatellites the model combines 361 000 doppler observations from clementine with 347 000 historical observations the historical data consist of mostly 60 s doppler with a noise of 0 25 to several mm s the clementine data consist of mostly 10 s doppler data with a data noise of 0 25 mm s for the observations from the deep space network and 2 5 mm s for the data from a naval tracking station at pomonkey maryland observations provided clementine provide the strongest satellite constraint on the moon s low degree field in contrast the historical data collected by spacecraft that had lower periapsis altitudes provide distributed regions of high resolution coverage within 29 of the nearside lunar equator to obtain the solution for a high degree field in the absence of a uniform distribution of observations we applied an a priori power law constraint of the form 15 10 5 l2 which had the effect of limiting the gravitational power and noise at short wavelengths coefficients through degree and order 18 are not significantly affected by the constraint and so the model permits geophysical analysis of effects of the major basins at degrees 10 12 the glgm 2 model confirms major features of the lunar gravity field shown in previous gravitational field models but also reveals significantly more detail particularly at intermediate wavelengths 103 km free air gravity anomaly maps derived from the new model show the nearside and farside highlands to be gravitationally smooth reflecting a state of isostatic compensation mascon basins including imbrium serenitatis crisium smythii and humorum are denoted by gravity highs first recognized from lunar orbiter tracking all of the major mascons are bounded by annuli of negative anomalies representing significant subsurface mass deficiencies mare orientale appears as a minor mascon surrounded by a horseshoe shaped gravity low centered on the inner and outer rook rings that is evidence of significant subsurface structural heterogeneity although direct tracking is not available over a significant part of the lunar farside glgm 2 resolves negative anomalies that correlate with many farside basins including south pole aitken hertzsprung korolev moscoviense tsiolkovsky and freundlich sharonov

gypsum scarps and asymmetric fluvial valleys in evaporitic terrains the role of river migration landslides karstification and lithology ebro river ne spain abstract most of the spanish fluvial systems excavated in tertiary evaporitic gypsum formations show asymmetric valleys characterized by a stepped sequence of fluvial terraces on one valley flank and kilometric long and 100 m high prominent river scarp on the opposite side of the valley scarp undermining by the continuous preferential lateral migration of the river channel toward the valley margin leads to vertical to overhanging unstable slopes affected by a large number of slope failures that become the main geological hazard for villages located at the toe of the scarps detailed mapping of the gypsum scarps along the ebro and huerva rivers gypsum scarps demonstrates that landslides and lateral spreading processes are predominant when claystones crop out at the base of the scarp while rockfalls and topples become the dominant movement in those reaches where the rock mass is mainly constituted by evaporites the dissolution of gypsum nodules seasonal swelling and shrinking and dispersion processes contribute to a decrease in the mechanical strength of claystones the existence of dissolution enlarged joints sinkholes and severely damaged buildings at the toe of the scarp from karstic subsidence demonstrates that the interstratal karstification of evaporites becomes a triggering factor in the instability of the rock mass the genesis of asymmetric valleys and river gypsum scarps in the study area seem to be caused by the random migration of the river channel in the absence of lateral tilting related to tectonics or dissolution induced subsidence once the scarp is developed its preservation depends on the physicochemical properties of the substratum the ratio between bedrock erosion and river incision rates and climatic conditions that favour runoff erosion versus dissolution

in situ characterization of flows in a fractured unstable slope in the case of large unstable mountain slopes the spatial repartition of the saturated zones influence the pressure repartitions in the massif and the slope stability this contribution proposes an evaluation of water origin and pressure transit time of groundwater flows from hydrochemical and isotopic measurements the objective is to propose a conceptual model of the groundwater flows and a location of the saturated zones in the slope the interpretation of time measurements of water pressure in the collapsed zone highlights i an evolution of flows with deformation that induces a damaging of the rock properties and ii the necessity to connect hydrogeological conditions and geological background in a dynamical system to analyse the pore pressure in the fractured collapsed zone

distributed acquisition characterization and process analysis of multi field information in slopes the slope is a multiphase composite system including solid liquid and gas phases slope stability changes under the actions of stress temperature and seepage slopes will be very prone to landslide if in an unstable state in this paper considering the contributions of different fields to the landslide the distributed acquisition characterization and stability analysis of multi field information from slopes was studied systematically using distributed fiber optic sensing dfos technology a sensing system based on dfos was designed and developed for multi field information monitoring including stress temperature seepage and deformation the corresponding methods for data processing identification and methods for characterization description are also proposed on this basis the evolution of the slope is analyzed finally monitoring results of the dfos system from the majiagou landslide are shown as a case study for verification

local lunar gravity field analysis over the south pole aitken basin from selene farside tracking data 1 we present a method with which we determined the local lunar gravity field model over the south pole aitken spa basin on the farside of the moon by estimating adjustments to a global lunar gravity field model using selene tracking data our adjustments are expressed in localized functions concentrated over the spa region in a spherical cap with a radius of 45 centered at 191 1 e 53 2 s and the resolution is equivalent to a 150th degree and order spherical harmonics expansion the new solution over spa was used in several applications of geophysical analysis it shows an increased correlation with high resolution lunar topography in the frequency band l 40 70 and admittance values are slightly different and more leveled when compared to other global gravity field models using the same data the adjustments expressed in free air anomalies and differences in bouguer anomalies between the local solution and the a priori global solution correlate with topographic surface features the moho structure beneath the spa basin is slightly modified in our solution most notably at the southern rim of the apollo basin and around the zeeman crater

comparison of the geochemistry of ophiolitic pyroxenites with a strongly fractionated dyke of pyroxenite from the sakhakot qila ophiolite pakistan abstract exceptionally strong fractionation has been found amongst the pyroxenite dykes crosscutting the ultramafic rocks of the sakhakot qila ophiolite pakistan one such dyke an fe websterite is particularly fractionated and anomalously feenriched and mg depleted this is supported by the data from whole rock analyses of major trace and rare earth elements as well as by the mineral chemistry of the constituent chromian spinel olivine clinopyroxene orthopyroxene and magmatic amphibole secondary sulphides of the fe websterite include troilite pentlandite instead of the awaruite heazle woodite pentlandite assemblage typical of all the other ultramafic rocks of the host ophiolite the non cumulate parent liquid of the magnesian pyroxenites crystallized in an initial episode when the surrounding cumulates were still hot in a belated second episode the fe websterite may have crystallized in isolated pockets after its differentiation to an extent much greater than that known from most pyroxenite dykes in ophiolites

power series solution for ponded infiltration on sloping surfaces summary recently it has been shown that the philip power series solution can also be applied for falling head ponded infiltration mollerup and hansen 2007 or more generally for variable head vh ponded infiltration on flat surfaces mollerup 2007 in this study it is shown that the power series solution can also be applied for vh ponded infiltration on sloping surfaces numerical simulations have been made for a guelph loam for a vh scenario the power series solution was compared with a 2d fem solution of richards equation with good agreement using the developed series solutions a vh scenario was compared with constant head ch simulations with both a ponding depth of zero and the average ponding depth as used in the vh simulations especially the latter gave small differences in the cumulative infiltration compared with the vh results simulations showed that cumulative infiltration normal to the slope as function of time is decreasing with increasing slope angles for similar vertical ponding depths corresponding to equal amount of surface water on a given horizontal slope section in contrast the infiltration on a given projected horizontal area increases with the slope angle

inversion of deformation fields time series from optical images and application to the long term kinematics of slow moving landslides in peru abstract slow moving landslides are numerous in mountainous areas and pose a large threat to populations many observations show that their kinematics is driven by climatic forcings and earthquakes in this study we document the complex interaction between those two forcings on the slow moving landslide kinematics based on the retrieval of landslide displacements over 28 years using optical satellite images to overcome the decorrelation effect over this large time span and possible misalignment between images we develop a method that uses the redundancy of displacement fields from image pairs to derive a robust time series of displacement the method is tested on the 28 year long spot1 5 pleiades archive over an area in peru affected by both earthquakes and rainfall errors are estimated on stable areas and by comparison with one 13 year long and eleven 3 year long gps time series on the maca landslide the methodology diminishes by up to 30 the uncertainty and reduces significantly the gaps due to decorrelation the data set allows detecting 3 major landslides moving at a rate of 35 to 50 m over 28 years and smaller landslides with lower displacement rates time series obtained over the three main landslides provide interesting results of their long term kinematics primarily driven by precipitation we propose simple statistical hydro kinematic models relating yearly motion to seasonal rainfall to explain the observed time series we found that annual precipitation is controlling the landslide displacements after a certain rainfall threshold is reached besides this control we show the possible impact of a local mw 5 4 earthquake in 1991 on the kinematics of the maca landslide our results suggest that the earthquake accelerated the landslide and has an effect during several years on the precipitation threshold required for triggering a motion these results suggest that the rainfall threshold can vary in time following strong earthquakes shaking

green ampt infiltration parameters from soils data the analysis of approx 5 000 soil horizons indicated that green and ampt parameters effective porosity wetting front capillary pressure and hydraulic conductivity could not be developed based on phases of soil order or suborder however sets of average parameters are developed based on soil horizon or soil texture class or both a procedure for determining the green and ampt parameters based on soil properties utilizing the full spectrum of soil survey information is outlined

dem based modelling of surface runoff using diffusion wave equation a digital elevation model dem based overland flow routing model was developed for computation of surface runoff for isolated storm events the model operates on a grid or cell basis and routes the rainfall excess generated over the cells following the dem derived drainage paths to the catchment outlet the rainfall excess for each cell of the catchment was computed using the philip two term infiltration model utilizing the physical properties of the cell the overland flow was described by a finite volume based numerical solution of the diffusion wave approximation of the st venant equations the cell physical properties such as topographic characteristics land use soil etc were extracted from published maps for discretized cells of the catchment using a geographic information system the results of model application indicate that the model satisfactorily predicted the runoff hydrograph the cell based structure of the model allowed for generation of spatially distributed catchment information in terms of the model computed variables such as the depth of flow and discharge

impact of slope gradient on soil surface features and infiltration on steep slopes in northern laos abstract it was recently demonstrated that infiltration into mountain tilled soils with highly stable microaggregates increases with increasing slope gradient in this work we investigate the processes that underpin this phenomenon by means of field experiments and modelling the study area is located in northern laos rainfall simulations were conducted in two 1 m 2 plots using a portable field simulator the drop size distribution and kinetic energy were similar to that occurring on the occasion of tropical downpours soils exhibited a clay loam texture and very similar organic matter contents across experimental plots but differed greatly in slope gradient 30 and 75 runoff water samples were collected at intervals ranging from 1 to 3 min depending on the runoff intensity plots microtopography was measured before and after rainfall simulations using an automatic surface roughness meter on a 1 cm grid high resolution bulk density images were obtained from soil slices using a standard x ray generator final infiltration rates of 6 and 21 mm h 1 soil detachment of 667 and 310 g m 2 surface lowering due to soil loss of 0 82 and 0 38 mm surface lowering due to compaction of 1 21 and 0 90 mm percentage area with sieving crust of 36 and 90 percentage area with erosion crust of 63 and 0 were obtained for the 30 and 75 slopes respectively three main conclusions can be drawn from this work 1 high intensity rainfall can rapidly transform soil surface features of steep bare soil 2 on steeper slopes the micro relief tends to form micro terraces much more pervious and less erodible than the ripple like roughness that formed on gentler slopes and 3 there was a more pronounced lowering of the soil surface due to compaction and denser microlayers on gentler slopes the latter conclusion confirms the hypothesis that higher effective rainfall intensity is responsible for the formation of less permeable erosion crusts under 30 slope gradients while more permeable structural crusts develop under 75 slope gradients the runoff results were modelled with the green and ampt model which accounts for time evolution of soil hydraulic conductivity this modelling shows that soil is undoubtedly non homogeneous evolves with time and that infiltration kinetics is slower and soil permeability greater for the 75 slope

the temporal stability and activity of landslides in europe with respect to climatic change teslec main objectives and results abstract the major aim of the european project the temporal stability and activity of landslides in europe with respect to climatic change teslec was to investigate the interrelationship between landslides climate and time the research was focused on three main objectives 1 developing criteria for the recognition of landslides 2 reconstructing past distributions of landslide incidents and their relationship to climatic change parameters and 3 developing a hydrological and slope stability modelling framework using different test sites the results of the project are related to these major objectives and include 1 a technical manual for landslide recognition 2 records of landslide activity and 3 an evaluation of different hydrological and slope stability models landslide activity since 1950 has been generally high at all test sites in some areas there has almost been a continuous activity observed since the beginning of the monitoring the records before 1950 are incomplete and probably indicate a lack of data rather than a lack of landslide activity whether the observed active landslides are carrying a climate signal cannot be stated for all test sites with high confidence since some relationships between climate and landslides are uncertain thus for the present the complexity of the relationships between climate and landsliding seems to make it not feasible to establish universal laws all over europe on the other hand it was possible to establish for some areas a cumulative rainfall duration threshold for the reactivation of landslides future scenarios of regional precipitation were derived from downscaled general circulation model gcm experiments and used within simple slope hydrological and slope stability models the evaluation of hydrological and slope stability models shows that physically based models are not always the best solution due to the model complexity and data requirements for shallow landslides more simple tank models are sometimes the better alternative future model development should strengthen considerations of fissure flow sudden changes in permeability larger landslide volumes and complex landslide topography

rare earth element geochemistry of thetford mines ophiolite complex northern appalachians canada the thetford mines complex is a complete ophiolite which is part of an ultramafic mafic belt within quebec appalachians these allochtonous bodies were emplaced during the early ordovician the thetford mines complex comprises a lower unit of metamorphic harzburgite in which tabular dyke like dunitic bodies occur overlain successively by ultramafic cumulates mafic cumulates ophitic gabbros diabase sills and dykes and basaltic volcanic rocks field evidence petrography and chemical data indicate that the tabular dunitic bodies formed when fractures in the metamorphic harzburgite which constituted the floor of the magma chamber filled with early cumulates i e olivine chromite representative rocks from all units were analyzed for major and rare earth elements ree metamorphic harzburgite samples from thetford mines complex have u shaped chondrite normalized ree patterns pyroxenites and wehrlites of the cumulate sequence are all strongly light ree depleted and have heavy ree ranging from 0 4 to 1 5 times chondrite ree data from ultramafic and volcanic rocks of thetford mines complex and geochemical modelling indicate that the metamorphic harzburgite has the chemical characteristics of depleted upper mantle residues with u shaped patterns and that the ultramafic cumulates crystallized from magmas having different la yb ratios

hillslope infiltration divergent and convergent slopes this perturbation analysis of divergence convergence effects on hillslope infiltration and downslope unsaturated flow indicates that in general these effects are unimportant for usual hillslope topography only where the radius of the contour is less than about 10 times the characteristic infiltration length lgrav or 10 times the sorptive length need the perturbation be taken into account this result opens up a considerable extension of applicability of the analysis of infiltration on planar hillslopes to embrace slopes with curved contours such as ridge noses and hollows

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

the influence of slope angle on final infiltration rate for interrill conditions abstract despite numerous studies the relationship between slope angle and infiltration rate remains unclear under different experimental conditions new processes may be introduced which influence the relationship the presence of rills for example may significantly affect the relationship between slope angle and infiltration rate so distinct relationships may exist for rill and interrill areas the objective of this study was to investigate the influence of slope angle on infiltration rate for an interrill area with a surface crust the experiment was carried out in a laboratory using simulated rainfall and soil trays designed to limit the processes to those found in interrill areas slope angles ranged from 1 5 to 21 5 infiltration was calculated from the overland flow rate and microtensiometers and micromorphological analysis were used to characterise the seals infiltration rate decreased with increasing slope angle image analysis of pore characteristics in the affected layer and subseal pressure head measurements indicated there were no differences in seal characteristics between slope angles the results showed that sealing intensity did not vary with slope angle and the dominant influence of slope angle on infiltration rate resulted from changes in overland flow depth and surface storage the results also suggest that small changes in seal hydraulic conductivity with microrelief play an important role in the infiltration process

regional moisture balance control of landslide motion implications for landslide forecasting in a changing climate i correlated 12 years of annual movement of 18 points on a large continuously moving deep seated landslide with a regional moisture balance index moisture balance drought index mbdi i used mbdi values calculated from a combination of historical precipitation and air temperature data from a d 1895 to 2010 and downscaled climate projections using the intergovernmental panel on climate change a2 emissions scenario for 2011 2099 at the landslide temperature is projected to increase 0 5 c 10 yr between 2011 and 2099 while precipitation decreases at a rate of 2 mm 10 yr landslide movement correlated with the mbdi with integration periods of 12 and 48 months the correlation between movement and mbdi suggests that the mbdi functions as a proxy for groundwater pore pressures and landslide mobility i used the correlation to forecast decreasing landslide movement between 2011 and 2099 with the head of the landslide expected to stop moving in the mid 21 st century the mbdi or a similar moisture balance index that accounts for evapotranspiration has considerable potential as a tool for forecasting the magnitude of ongoing deep seated landslide movement and for assessing the onset or likelihood of regional deep seated landslide activity

falling head ponded infiltration it is remarkable that the green ampt or delta function solution for falling head ponded infiltration takes precisely the same functional form as that for constant head infiltration only the values of the constants change falling head infiltration experiments are thus as amenable to green ampt analysis as more complicated constant head experiments

fiber bundle model for multiscale modeling of hydromechanical triggering of shallow landslides 1 sudden and rapid mass movements associated with landslides and snow avalanches present a hazard to life and infrastructure yet their predictions and triggering mechanisms remain poorly understood statistical methods and correlative studies have been used to produce landslide or avalanche susceptibility maps often with limited physical basis mechanistic approaches based on factor of safety computation seldom represent the progressive transition from local failure events to a landslide and in general do not include heterogeneities associated with land cover or with subsurface material properties and hydrologic pathways focusing on rainfall induced shallow landslides we propose the use of the fiber bundle model fbm a generic yet powerful and adaptable model used in modeling fatigue and fracture of complex and disordered materials the primary strength of the fbm is its ability to represent the progressive failure of cracks and shear zones and the ruptures of highly heterogeneous bonding elements that are present in soils at all scales the model also provides a natural framework for interpretation of acoustic emission signatures from failing slopes which may form the basis of a monitoring and warning system

green ampt infiltration model for sloping surfaces 1 this work quantifies and explains the direct physical effects of slope angle on infiltration and runoff generation by extending the green ampt equation onto sloping surfaces a new extended solution using identical precipitation hydrographs was compared to the original formulation and then used to calculate the infiltration and runoff generation for different slope angles but for identical horizontal projection lengths homogeneous and isotropic soil is assumed and two different boundary conditions for vertical rainfall are studied ponded infiltration and infiltration under steady rainfall infiltration under unsteady rainfall was found to be similar to cases with steady rainfall both theoretical and numerical results show that infiltration increases with increasing slope angle for cases with ponded infiltration the slope effect was generally not significant for mild to moderate slopes but the slope effect became more important for low intensity and short duration rainfall events especially as it delayed the time for ponding it was also found that the cumulative vertical infiltration depth ihp at ponding or the initial loss increases with increasing slope angle the model was compared to richards equation on horizontal and sloping surfaces and found to perform well the model s applicability for nonuniform slopes was discussed and it was found that the model is generally applicable for isotropic and mildly anisotropic soils except for some small scale topographic elements finally the occurrence of nonvertical rainfall could increase runoff with increasing slope angle when rainfall deflects a large angle to upslope

stratigraphy and geochemistry of the lac brompton ophiolite canada evidence for extensive forearc magmatism and mantle exhumation in the southern quebec ophiolite belt three ophiolites are currently recognized in the southern quebec appalachians from south to north the mont orford ophiolite dominated by tholeiitic to transitional alkaline basalt and diabase a

new analysis of lunar prospector radio tracking data brings the nearside gravity field of the moon with an unprecedented resolution abstract a new analysis of the doppler tracking data from the lunar prospector mission in 1999 revealed a number of previously unseen gravity anomalies at spatial scales as small as 27 km over the nearside the tracking data at low altitudes 50 km or below were better analyzed to resolve the nearside features without dampening from a power law constraint by partitioning the gravity parameters concentrated on either the nearside or farside the resulting model presents gravity anomalies correlated with topography with a correlation coefficient of 0 7 or higher from degree 50 to 150 the widest bandwidth yet the gravity topography admittance of 70 mgal km is found from numerous craters of which diameters are 60 km or less in addition the new model produces orbits that fit to independent radio tracking data from the lunar reconnaissance orbiter and kaguya selene better than previous gravity models this high resolution model can be of immediate use to geophysical analysis of small craters our technique could be applied to an upcoming mission the gravity recovery and interior laboratory and useful to extract short wavelength signals from the messenger doppler data

the geochemistry and petrogenesis of ophiolitic volcanic rocks from lac de l est thetford mines complex quebec canada discussion oshin and crocket in an important contribution to the studv lac de 1 est volcanics mor or arc rocks of low ti ophiolite complexe in the appalachians suggest that the high3 tio rocks of the lac de 1 est volcanic sequence associated with the thetford ophiolite show some chemical characteristics of mid oceanic ridge mor basalts and partly for this reason they favour a back arc marginal basin as a site of origin for these rocks such an interpretation although first considered over 15 years ago has always lacked credibility however because of the apparent absence of bounding arc elements in association with the supposed backarc ophiolites consequently it has been proposed pearce et al 1984 that ophiolites such as thetford and troodos are a manifestation of the formation of near trench spreading centres during the very early stages of arc development it is in this context that i would like to reexamine the data presented by oshin and crocket for the lac de 1 est volcanic sequence and discuss the tectonic implications of a revised interpretation

improved regional gravity fields on the moon from lunar prospector tracking data by means of localized spherical harmonic functions 1 an approach to enhance regional gravity fields of the planets using the line of sight los doppler range rate measurements is presented instead of representing the gravity fields as nonlocalized spherical harmonic functions i introduced a lumped harmonic representation for obtaining regionally concentrated orthogonal basis functions without any regularization or spectral power control the gravity fields over the four spherical cap regions with the radius of 20 on the nearside of the moon to degree and order 200 were estimated using all 8 months of the extended mission data from lunar prospector the regional models are variations on the initial global gravity model lp100j it was found that the regional estimates significantly improve the initial gravity model at all four regions of interest my improved gravity models fit the los doppler range acceleration data better than any other global lunar gravity model especially the data for when the satellite was at low altitude 40 km or less in addition a better cross correlation with the topography was obtained from the regional model the regional enhancement of the correlation was prominent in degrees greater than 100 and in polar regions characterized by clusters of medium or small size craters that are presumably uncompensated

infiltration and deep flow over sloping surfaces comparison of numerical and experimental results summary infiltration and deep flow on sloping surfaces were studied by combining controlled laboratory experiments with mathematical models experimental variables included soil types rainfall intensities and surface slopes preliminary analyses of the data indicated that increased slope has a positive influence on surface flow and that this influence increases relatively with decreasing rainfall rate however current theories could not adequately explain the observed behavior of deep and surface flows for varying slopes three mathematical models of varying complexity were employed to supplement the experimental results these models were i the 2 d hydrus numerical model ii numerical solution of 1 d saturated unsaturated flow equation on sloping surfaces and iii a simplified 1 d sharp front model for sloping surfaces for the latter two models a surface flow component based on the kinematic wave approximation for shallow flows was externally coupled to the subsurface flows to route water over the soil surface for each soil one experiment at the lowest slope and rainfall rate was utilized for estimation of model parameters that could not be measured independently while all the other results were used for model corroboration the hydrus model indicated that a 1 d analysis would be adequate as the water front moves essentially parallel to the slope to account for the influence of slope and soil type on experimental results an effective saturated conductivity was proposed model results were found to be in reasonable agreement with observations of surface flow deep flow and water contents in the soil profile with the use of the proposed effective saturated conductivity limitations on the applicability of the sharp front model in this context were discussed

hillslope infiltration planar slopes the solution of the full nonlinear unsaturated flow equation is given for a problem of infiltration and associated subsurface flows into a planar hillslope of a homogeneous isotropic soil with uniform initial moisture content the solution uses the assumption that at some distance below the slope crest a spatial equilibrium is approached with the moisture content and other properties independent of downslope coordinate x and dependent only on the normal coordinate z and time t the analysis is found to be generally applicable beyond a small distance from the slope crest or from a point of slope change for slope angles less than 30 infiltration normal to the slope differs relatively little from infiltration from a horizontal surface interesting aspects of the solution include a time independent total horizontal flow into the slope and a time dependent downslope total flow component which behaves as t1 2 at small t and as t at large t previously hillslope flows in these directions have been discussed in terms of soil anisotropy and layering but these flows in a homogeneous isotropic soil are simple physical consequences of capillarity and gravity the analysis applies with minor modification to two simple types of hillslope anisotropy 1 anisotropy parallel to the slope and 2 horizontal anisotropy type 1 yields a complicated time dependence of the horizontal flow and type 2 affects downslope flow similarly these flow directions will commonly reverse during the course of the infiltration process

lunar global shape and polar topography derived from kaguya lalt laser altimetry a global lunar topographic map with a spatial resolution of finer than 0 5 degree has been derived using data from the laser altimeter lalt on board the japanese lunar explorer selenological and engineering explorer selene or kaguya in comparison with the previous unified lunar control network ulcn 2005 model the new map reveals unbiased lunar topography for scales finer than a few hundred kilometers spherical harmonic analysis of global topographic data for the moon earth mars and venus suggests that isostatic compensation is the prevailing lithospheric support mechanism at large scales however simple rigid support is suggested to dominate for the moon venus and mars for smaller scales which may indicate a drier lithosphere than on earth especially for the moon and venus

estimation of sorptivity from disc permeameter measurements the use of disc permeameter in the field often requires the placement of a layer of sand in order to provide good contact between the soil surface and disc supply membrane the effect of the contact sand on water infiltration into the soil and the estimate of sorptivity s was investigated a numerical study using a loam and clay and a field experiment on heavy clay was conducted placement of the sand significantly increased the cumulative infiltration but showed small differences in the final infiltration rate estimation of s based on philip s two term algebraic model using different methods was also examined conventionally s is estimated from the early time infiltration rate when the capillary force is dominating but results showed that this method always overestimated s and give the largest error a numerical study indicated that differentiating the cumulative infiltration with respect to the square root of time provided the closest estimate of s compared to the true value and furthermore showed small variations between treatments with contact sand field experiment revealed that the error in infiltration measurements followed the pattern of the infiltration curve the absolute rate of infiltration without placement of sand was considerably lower because of the poor contact between the disc and soil surface thus contact sand is recommended although care must be exercised with the interpretation of the data

landslide development at the shores of a dam reservoir wloclawek poland based on 40 years of research this article presents results of our 40 year research on dynamics of a deep rotational landslide developed in clay deposits the landslide is located in a lowland within the shoreline of wloclawek reservoir with little water level variation in dobrzyn on the vistula northern poland it is an old landslide which was active also before the construction of the reservoir our research was initiated in 1970 i e when the river vistula was dammed there currently the landslide covers about 20 000 m2 and has a volume of about 160 000 m3 during the 40 years 3 periods of increased landslide activity were observed the first conspicuously nearly 40 increase in the rate of movements within the central landslide was initiated in the early 1970s and lasted till the early 1980s it coincided with the initial filling of the reservoir and the first years of exploitation of wloclawek reservoir the increase in landslide dynamics was a direct effect of hydrological and morphological changes associated with the damming of the river the next 2 periods of increased landslide activity occurred in 2001 2002 and 2010 2011 the latter was the most spectacular displacement within the central landslide it was recorded between december 2010 and february 2011 and reached 10 0 19 4 m after unusually long lasting heavy rainfall in the summer and autumn of 2010 followed by snowmelt and unfavourable changes in air temperature since march 2011 no movements within the landslide have been recorded

geochemistry of an ophiolitic complex from new caledonia the ophiolites of new caledonia are composed of ultramafics overlain by mafic rocks all of which were affected by low p metamorphism the mafic rocks studied gabbroic cumulates and basaltic flows and dikes from montagne des sources are similar to recent mid ocean ridge rocks they are olivine normative with mg mg fe2 ratios ranging from 0 69 in lavas to 0 90 in gabbroic cumulates and show tholeiitic fractionation trends such as a negative correlation of ti and v with the mg fe ratio the lavas have a flat ree pattern with a slight depletion of light ree and a la yb ratio 2 the dikes have three different types of ree patterns the first type is nearly parallel to that of lavas the second one is enriched in lree la yb 4 and the third type with the lowest ree contents and a distinct lree depletion is similar to that of cumulitic pyroxene gabbro the variations in chemical compositions of the mafic rocks can be accounted for by the dynamic partial melting process of langmuir et al 1977 in agreement with structural and tectonic observations the geochemical data suggests that the ophiolites were formed during the spreading of a mid ocean ridge with a spreading half rate of about 1 cm year

the role of the degree of weathering and groundwater fluctuation in landslide movement in a colluvium of weathered hornblende gabbro abstract shallow translational earth sliding induced by heavy rainfall in slopes made of colluvium of weathered homblende gabbro was investigated in order to elucidate the relationship between weathering soil strength and slope instability the earth slide has a length of 100 m and a maximum width of 40 m and an average depth of about 6 4 m average rate of the initial sliding in early summer of 1976 was estimated to be about 50 mm day and the sliding intermittently continued to the end of 1977 sliding became active due to rising of groundwater table in response to rainfall the average slope angle reduced from 13 9 to 11 3 as a result of the sliding mineralogical investigations indicated that 1 the sliding surface of this earth slide was located in the colluvium of weathered debris from the hornblende gabbro and 2 hornblende in gabbro was altered due to weathering into swelling chlorite geotechnical properties of the colluvium were measured shear tests gave values of c p 0 169 kgf cm2 and p 27 8 for peak strength and c r 0 122 kgf cm2 and r 10 6 for residual strength the infinite slope stability analyses using these values indicated that 1 the soil strength had reduced to the residual strength at the time of initial sliding 2 the analyses using the residual strength well explain the results of the field measurements showing that the earth slide is active when the groundwater table rises to near the slope surface and 3 the slope of 11 3 the post sliding angle is stable even under the most severe condition even when the groundwater rises to the slope surface these results suggest that the sliding surface had been already made before the 1976 1977 event the existing literature shows that chlorite will alter to smectite minerals having a smaller strength r 4 5 as a result of further weathering using this value the ultimate angle of stable slope was estimated to be 8 based on the discussion an idealized diagram illustrating the relationship between weathering strength and slope instability of this hillslope was constructed

history of landslide susceptibility and a chorology of landslide prone areas in the western ghats of kerala india kerala is the third most densely populated state in india it is a narrow strip of land of which 47 is occupied by the most prominent orographic feature of peninsular india the western ghats mountain chain the highlands of kerala experience several types of landslides of which debris flows are the most common they are called urul pottal in the local vernacular the west facing western ghats scarps that runs the entire extent of the mountain system is the most prone physiographic unit for landslides the highlands of the region experience an annual average rainfall as high as 500 cm through the south west north east and pre monsoon showers a survey of ancient documents and early news papers indicates a reduced rate of slope instability in the past the processes leading to landslides were accelerated by anthropogenic disturbances such as deforestation since the early 18th century terracing and obstruction of ephemeral streams and cultivation of crops lacking capability to add root cohesion in steep slopes the events have become more destructive given the increasing vulnerability of population and property majority of mass movements have occurred in hill slopes 20 along the western ghats scarps the only exception being the coastal cliffs studies conducted in the state indicates that prolonged and intense rainfall or more particularly a combination of the two and the resultant pore pressure variations are the most important trigger of landslides the initiation zone of most of the landslides was typical hollows generally having degraded natural vegetation a survey of post landslide investigation and news paper reports enabled the identification of 29 major landslide events in the state all except one of the 14 districts in the state are prone to landslides wayanad and kozhikode districts are prone to deep seated landslides while idukki and kottayam are prone to shallow landslides

determination and localized analysis of intersatellite line of sight gravity difference results from the grail primary mission 1 the line of sight los gravity difference between two coorbiting spacecrafts is determined in terms of intersatellite range acceleration measurements available from the gravity recovery and interior laboratory grail the precise orbit data are crucial for retrieving gravity difference from range acceleration and aligning the los data particularly in altitude a relative orbit error of a few centimeters in position and a few tens m s in velocity is commensurate with the grail ranging instrument noise at a few gal in los gravity difference the power spectrum as well as the topography correlation and admittance is quantified by upward continuing the topographic potential forward modeling the los gravity along the spacecraft trajectory i e bouguer correction and comparing with the grail los observations based on the data analysis from the primary grail mission i found that the los gravity difference observation produced near unity correlation with topography potential out to degree 550 higher than the global estimate over the areas covered by the low altitude orbit 20 km the crustal density was estimated to be 2500 2600 kg m3 with regional variations of about 10 by minimizing the bouguer coherence of the grail data at the degree band 150 300 systematic decrease in the density estimates by 3 4 or 100 kg m3 was observed at shorter wavelengths degree band 300 500 it implies the inadequacy of a uniform density model across the entire lithosphere and suggests radial stratification of the bulk density or porosity due to spatially localized characteristic the los gravity difference data are well suited to regional analysis at the highest possible resolution

improved nearside gravity field of the moon by localizing the power law constraint 1 the problem associated with the large data gap on the farside of the moon is addressed for constructing a high resolution global gravity model by localizing the power law constraint and making it effective only within the farside and limb regions we mitigate the undesired power limiting effect on the nearside compared to the solution estimated from lunar prospector and other satellite tracking data with the globally applied power law the locally constrained solution shows significant improvement of the nearside gravity estimates around the areas dominated by craters in the southern hemisphere of the nearside the correlation with topography approaches nearly 0 95 and the admittance converges to 100 110 mgal km up to spherical harmonic degree 130 while the globally constrained solutions distort starting at degree 90 the proposed analysis can benefit the science and operation of other existing and future planetary missions and enhance the geophysical interpretation of the gravity field

geochemistry of mount orford ophiolite complex northern appalachians canada abstract the orford ophiolite complex is part of an ultramafic mafic belt occurring within the quebec appalachians these allochtonous bodies were emplaced during the early ordovician the orford complex comprises from bottom to top ultramafic cumulate rocks dunite to pyroxenite gabbros sheeted sills diabase and volcanic rocks representative rocks 10 ultramafic cumulate rocks 5 gabbros 8 diabases 8 volcanic rocks from all rock units were analysed for major elements and ba cr ni rb sr y zn zr and ree rare earth element abundances in cumulate dunites are 0 04 0 08 chondrite pyroxene bearing cumulates are all strongly lree depleted and have hree abundances ranging from 0 6 to 2 5 chondrite some gabbros analysed have up to 40 45 chondrite hree the diabases of the sheeted sill complex and the volcanic rocks have morb like ree patterns geochemical modelling of the ree strongly suggests that ultramafic cumulates gabbros sheeted sills and volcanic rocks are coeval and were derived from a lree depleted morb type lherzolitic mantle source an arc environment is favoured as a tectonic setting for the mount orford ophiolite complex

a view on some hydrological triggering systems in landslides abstract in this paper different types of hydrological triggering systems for debris flows shallow and deeper landslides are described the generation of surface run off and high peak discharges in first order alpine catchments is an important triggering mechanism for debris flows failure conditions in shallow landslides can occur when at a critical depth which is determined by the cohesion of the soil and the slope angle the moisture content in the soil becomes close to saturation resulting in a considerable reduction of soil strength deeper landslides 5 20 m depth are in most cases triggered by positive pore pressures on the slip plane induced by a rising ground water level the assessment of meteorological threshold conditions for shallow landslides 1 2 m needs more detailed meteorological information than for deeper landslides in the analyses of the hydrological triggering systems of deeper landslides the presence of a permeable top layer and fissures has to be taken into consideration

an improved approach for evaluating the time dependent stability of colluvial landslides during intense rainfall the paper presents an improved analytical approach for evaluating the time dependent stability of colluvial landslides during intense rainfall infiltration the approach comprises two steps first to simulate rainfall infiltration and then to compute the safety factor in terms of the irregularity of the natural landslide surface in implementation of the method the landslide is divided into several soil slices with approximately straight sides each single slice is regarded as a finite slope so that the infiltration formula and safety factor can be deduced the infiltration formula is derived with combination of the green ampt model and mass conservation law considering seepage perpendicular and parallel to slope surface simultaneously in the modified infiltration model both size effect and angle effect are vividly observed in the process of rainfall infiltration into the finite slope while the former of which is not presented in the original green ampt model the safety factor is computed using the limit equilibrium method with the influence of infiltrating water on the shear strength gravity and seepage force of soil slices considered by case study of the shuping landslide in three gorges decline in the safety factor and the decrease in the tendency are definite specifically under the rainfall intensity of 50 mm h the failure of shuping landslide is most likely to occur at the time of 102 h in addition the results highlight shallow failure along the wetting front under intense rainfall

a pore pressure diffusion model for estimating landslide inducing rainfall many types of landslide movement are induced by large rainstorms and empirical rainfall intensity duration thresholds for initiating movement have been determined for various parts of the world in this paper i present a simple pressure diffusion model that provides a physically based hydrologic link between rainfall intensity duration at the ground surface and destabilizing pore water pressures at depth the model approximates rainfall infiltration as a sinusoidally varying flux over time and uses physical parameters that can be determined independently if destabilizing pore pressures can be estimated then the model enables the development of a stability criterion defining destabilizing rainfall intensity duration conditions using a comprehensive data set from an intensively monitored landslide i demonstrate that the model is capable of distinguishing movement inducing rainstorms

farside gravity field of the moon from four way doppler measurements of selene kaguya the farside gravity field of the moon is improved from the tracking data of the selenological and engineering explorer selene via a relay subsatellite the new gravity field model reveals that the farside has negative anomaly rings unlike positive anomalies on the nearside several basins have large central gravity highs likely due to super isostatic dynamic uplift of the mantle other basins with highs are associated with mare fill implying basalt eruption facilitated by developed faults basin topography and mantle uplift on the farside are supported by a rigid lithosphere whereas basins on the nearside deformed substantially with eruption variable styles of compensation on the near and farsides suggest that reheating and weakening of the lithosphere on the nearside was more extensive than previously considered

modelling suspended sediment concentration and load in a transport limited alluvial gully in northern queensland australia alluvial gullies are often formed in dispersible sodic soils along steep banks of incised river channels field data collected by shellberg et al earth surface processes and landforms 38 1765 1778 2013 from a gully outlet in northern australia showed little hysteresis between water discharge and fine 63 m suspended sediment indicating transport limited rather than source limited conditions the major source of the fine silt clay component was the sodic soils of upstream gully scarps and the coarser sand component was sourced locally from channel bed material in this companion paper at the same study site a new method was developed for combining the settling velocity characteristics of these two sediment source components to estimate the average settling velocity of the total suspended sediment this was compared to the analysis of limited sediment samples collected during flood conditions these settling velocity data were used in the steady state transport limit theory of hairsine and rose water resources research 28 237 243 245 250 1992 that successfully predicted field data of concentrations and loads at a cross section regardless of the complexity of transport limited upstream sources sheet erosion scalds rills gullies mass failure bank and bed erosion other disturbed areas the analysis required calibration of a key model parameter the fraction of total stream power f 0 025 that is effective in re entraining sediment practical recommendations are provided for the prediction of sediment loads from other alluvial gullies in the region with similar hydrogeomorphic conditions using average stream power efficiency factors for suspended silt clay fw 0 016 and sand fs 0 038 respectively but with no requirement for field data on sediment concentrations only basic field data on settling velocity characteristics from soil samples channel geometry measurements estimates of water velocity and discharge and associated error margins are needed for transport limit theory predictions of concentration and load this theory is simpler than that required in source limited situations copyright 2015 john wiley sons ltd

tracer test to assess flow and transport parameters of an earth slide the montecagno landslide case study italy abstract subsurface water processes are principle triggering and driving factors during slope movements however the hydraulic properties that drive groundwater flow along the slope remain poorly understood moreover landslide deposits are often characterized by layering and fissures that cause high heterogeneity in the distribution of hydraulic properties this heterogeneity leads to great uncertainty in the prediction of groundwater flow paths this study aimed to improve understanding of hydraulic and transport properties of deep earth slides and to identify preferential flow directions inside the landslide body a dye tracer test was used to estimate transport parameters and characterize groundwater flow paths the results indicate that in the studied landslide two groundwater flow types exist and are related to the presence of fissured rock blocks and debris horizons embedded in a fine matrix the estimated low groundwater flow velocity has rarely been estimated in other studies of this landslide type the groundwater flow direction appears to be mainly influenced by the failure surface shape and differs from the sliding direction our results differ from those in other landslide studies and improve our knowledge of groundwater flow properties in deep earth slides furthermore they offer a new contribution to slope stability analyses and formula and to the effective design of mitigation strategies

groundwater flow and mixing in a wetland stream system field study and numerical modeling summary we combined electrical resistivity tomography ert on land and in a stream with zone based hydraulic conductivities from multi level slug testing to investigate the local geological heterogeneity of the deposits in a wetland stream system the detailed geology was incorporated into a numerical steady state groundwater model that was calibrated against average head observations the model results were tested against groundwater fluxes determined from streambed temperature measurements discharge varied up to one order of magnitude across the stream and the model was successful in capturing this variability water quality analyses from multi level sampling underneath the streambed and in the wetland showed a stratification in groundwater composition with an aerobic shallow zone with oxygen and nitrate top 3 m overlying a reduced anoxic zone while no 3 concentrations up to 58 mg l 1 were found in the top of the aquifer and immediately underneath the streambed no no 3 was detected deeper within the aquifer an inverse relationship between no 3 and so 4 2 suggests that pyrite oxidation takes place in the deeper parts of the aquifer simulated flow path lines showed very different origins for deeper groundwater samples no nitrate reduction is believed to occur in the shallow zone where oxygen is present and the residence time is on the order of 1 year nitrate reduction can however occur in the deeper parts which are oxygen free and where the residence time is on the order of 7 years a simulation with a homogeneous model did not match the observations nearly as well as a heterogeneous model based on ert and a spatially distributed hydraulic conductivity furthermore the origin of the sampled groundwater could not have been predicted from groundwater hydraulic head and the groundwater chemistry alone the presented approach of integrating such methods in groundwater surface water exchange studies proved efficient to obtain information of the controlling factors

analysis of rainfall induced infinite slope failure during typhoon using a hydrological geotechnical model rainwater infiltration during typhoons tends to trigger slope instability this paper presents the results of a study on slope response to rainwater infiltration during heavy rainfall in a mountain area of taiwan the green ampt infiltration model is adopted here to study the behavior of rainwater infiltration on slopes the failure mechanism of infinite slope is chosen to represent the rainfall induced shallow slope failure by combining rain infiltration model and infinite slope analysis the proposed model can estimate the occurrence time of a slope failure in general if a slope failure is to happen on a slope covered with low permeability soil failure tends to happen after the occurrence of the maximum rainfall intensity in contrast slope failure tends to occur prior to the occurrence of maximum rainfall intensity if a slope is covered with high permeability soil to predict the potential and timing of a landslide a method is proposed here based on the normalized rainfall intensity nri and normalized accumulated rainfall nar if the actual nar is higher than the nar calculated by the proposed method slope failure is very likely to happen otherwise the slope is unlikely to fail the applicability of the proposed model to occurrence time and the nar nri relationship is evaluated using landslide cases obtained from the literature the results of the proposed method are close to that of the selected cases it verifies the applicability of the proposed method to slopes in different areas of the world

simplified approach for the analysis of rainfall induced shallow landslides this paper presents a simplified approach for the analysis of shallow landslides triggered by heavy rainfalls which occur after a rainy period on the basis of some analytical solutions this approach combines a simple infiltration model to calculate the change in pore water pressure caused by rain infiltration within the slope with a sliding block model to assess whether a slope failure occurs owing to a prescribed rainfall if this is the case the method also allows the time at which the landslide is triggered and the subsequent slope movements to be readily evaluated

change point analysis of geophysical time series application to landslide displacement rate sechilienne rock avalanche france the rank sum multiple change point method is a robust statistical procedure designed to search for the optimal number and the location of change points in an arbitrary continue or discrete sequence of values as such this procedure can be used to analyse time series data twelve years of robust data sets for the sechilienne french alps rockslide show a continuous increase in average displacement rate from 50 to 280 mm per month in the 2004 2014 period followed by a strong decrease back to 50 mm per month in the 2014 2015 period when possible kinematic phases are tentatively suggested in previous studies its solely rely on the basis of empirical threshold values in this paper we analyse how the use of a statistical algorithm for change point detection helps to better understand time phases in landslide kinematics first we test the efficiency of the statistical algorithm on geophysical benchmark data these data sets stream flows and northern hemisphere temperatures being already analysed by independent statistical tools second we apply the method to 12 yr daily time series of the sechilienne landslide for rainfall and displacement data from 2003 december to 2015 december in order to quantitatively extract changes in landslide kinematics we find two strong significant discontinuities in the weekly cumulated rainfall values an average rainfall rate increase is resolved in 2012 april and a decrease in 2014 august four robust changes are highlighted in the displacement time series 2008 may 2009 november december 2010 january 2012 september and 2014 march the 2010 one being preceded by a significant but weak rainfall rate increase in 2009 november accordingly we are able to quantitatively define five kinematic stages for the sechilienne rock avalanche during this period the synchronization between the rainfall and displacement rate only resolved at the end of 2009 and beginning of 2010 corresponds to a remarkable change fourfold increase in mean displacement rate in the landslide kinematic this suggests that an increase of the rainfall is able to drive an increase of the landslide displacement rate but that most of the kinematics of the landslide is not directly attributable to rainfall amount the detailed exploration of the characteristics of the five kinematic stages suggests that the weekly averaged displacement rates are more tied to the frequency or rainy days than to the rainfall rate values these results suggest the pattern of sechilienne rock avalanche is consistent with the previous findings that landslide kinematics is dependent upon not only rainfall but also soil moisture conditions as known as being more strongly related to precipitation frequency than to precipitation amount finally our analysis of the displacement rate time series pinpoints a susceptibility change of slope response to rainfall as being slower before the end of 2009 than after respectively the kinematic history as depicted by statistical tools opens new routes to understand the apparent complexity of sechilienne landslide kinematic

modification of the kinematic wave philip infiltration overland flow model in previous work a solution was developed for the kinematic wave overland flow equation with rainfall excess given by philip s infiltration equation subsequent application of this solution to field data from small plots revealed the need for an improved model the principal requirement is the incorporation of depression storage into the rising limb calculation a second requirement is a more precise approximation of the water surface profile at the end of rainfall this improves the falling limb calculations this paper shows the solutions obtained by incorporating these improvements and demonstrates their effects on predicted hydrographs and water surface profiles

modeling rainfall infiltration on hillslopes using flux concentration relation and time compression approximation abstract rainfall infiltration on hillslopes is an important issue in hydrology which is related to many environmental problems such as flood soil erosion and nutrient and contaminant transport this study aimed to improve the quantification of infiltration on hillslopes under both steady and unsteady rainfalls starting from darcy s law an analytical integral infiltrability equation was derived for hillslope infiltration by use of the flux concentration relation based on this equation a simple scaling relation linking the infiltration times on hillslopes and horizontal planes was obtained which is applicable for both small and large times and can be used to simplify the solution procedure of hillslope infiltration the infiltrability equation also improved the estimation of ponding time for infiltration under rainfall conditions for infiltration after ponding the time compression approximation tca was applied together with the infiltrability equation to improve the computational efficiency the analytical integral infiltrability equation was approximated with a two term power like function by nonlinear regression procedures of applying this approach to both steady and unsteady rainfall conditions were proposed to evaluate the performance of the new approach it was compared with the green ampt model for sloping surfaces by chen and young 2006 and richards equation the proposed model outperformed the sloping green ampt and both ponding time and infiltration predictions agreed well with the solutions of richards equation for various soil textures slope angles initial water contents and rainfall intensities for both steady and unsteady rainfalls

the national landslide database of great britain acquisition communication and the role of social media the british geological survey bgs is the national geological agency for great britain that provides geoscientific information to government other institutions and the public the national landslide database has been developed by the bgs and is the focus for national geohazard research for landslides in great britain the history and structure of the geospatial database and associated geographical information system gis are explained along with the future developments of the database and its applications the database is the most extensive source of information on landslides in great britain with over 17 000 records of landslide events to date each documented as fully as possible for inland coastal and artificial slopes data are gathered through a range of procedures including incorporation of other databases automated trawling of current and historical scientific literature and media reports new field and desk based mapping technologies with digital data capture and using citizen science through social media and other online resources this information is invaluable for directing the investigation prevention and mitigation of areas of unstable ground in accordance with government planning policy guidelines the national landslide susceptibility map geosure and a national landslide domains map currently under development as well as regional mapping campaigns rely heavily on the information contained within the landslide database assessing susceptibility to landsliding requires knowledge of the distribution of failures an understanding of causative factors their spatial distribution and likely impacts whilst understanding the frequency and types of landsliding present is integral to modelling how rainfall will influence the stability of a region communication of landslide data through the natural hazard partnership nhp and hazard impact model contributes to national hazard mitigation and disaster risk reduction with respect to weather and climate daily reports of landslide potential are published by bgs through the nhp partnership and data collected for the national landslide database are used widely for the creation of these assessments the national landslide database is freely available via an online gis and is used by a variety of stakeholders for research purposes

hydrological triggering conditions of landslides in varved clays in the french alps abstract in this paper the meteorological and hydrological conditions are analyzed which trigger shallow and deeper landslides in glacio lacustrine deposits varved or laminated clays in the french alps the hydrological system of these landslides consists of a colluvial cover which supplies water into the fissures of the underlying varved clays from these fissures water can infiltrate more or less horizontally into the silt layers of the varved clays a combined reservoirs model was used to simulate the water fluctuations in the colluvial cover and the fissures both the water level in the fissures and the residence time of water in the fissures are mainly controlled by the amount of water storage in the colluvial cover simulations over the last 25 years show that almost each year the fissures are completely filled with water for several months a year infiltration experiments in the field show that infiltration into the varved clays occurs mainly by horizontal infiltration into the silt laminae calculated infiltration rates from these fissures into the silt layers show that the mean yearly residence time of water in the fissures is not sufficient to fully saturate the clay mass each year it is therefore concluded that the triggering of the landslide movements is mainly controlled by the development of positive pore water pressures in the fissure system and that the rise of pore water pressures induced by the matrix system of the varved clays only plays a minor role the calculations also show that drainage of the colluvial cover is a very efficient measure to stabilize the deeper landslides

the gravity field of mars results from mars global surveyor observations of the gravity field of mars reveal a planet that has responded differently in its northern and southern hemispheres to major impacts and volcanic processes the rough elevated southern hemisphere has a relatively featureless gravitational signature indicating a state of near isostatic compensation whereas the smooth low northern plains display a wider range of gravitational anomalies that indicates a thinner but stronger surface layer than in the south the northern hemisphere shows evidence for buried impact basins although none large enough to explain the hemispheric elevation difference the gravitational potential signature of tharsis is approximately axisymmetric and contains the tharsis montes but not the olympus mons or alba patera volcanoes the gravity signature of valles marineris extends into chryse and provides an estimate of material removed by early fluvial activity

shallow landslide susceptibility assessment in a semiarid environment a quaternary catchment of kwazulu natal south africa abstract this paper presents an evaluation of landslide susceptibility maps based on the frequency ratio fr landslide susceptibility index lsi logistic regression lr and artificial neural network ann methods applied within a quaternary catchment in the kwazulu natal region south africa landslide occurrence in this particular catchment is generally induced by heavy rainfall events where shallow landslips occur mostly on steep slopes thereby threatening informal housing at the base of slopes the scope of this study is to compare the performance of landslide susceptibility models and rate the importance of landslide causal factors thirteen landslide causal factors including altitude slope angle aspect slope total curvature slope plan curvature slope profile curvature proximity to stream network topographic wetness index twi lithology land cover proximity to faults proximity to dolerite sills and dykes and proximity to the road network were considered in the study furthermore each causal factor was rated according to the above mentioned methods and it was found that the most influential landslide causal factors are the altitude land cover and lithology the resulting susceptibility maps were classified into 5 classes ranging from very low to very high susceptibility model performance was tested using an independent validation set comprising 10 of all mapped landslides for verification of the models performance receiver operating curves rocs were calculated and the areas under curve auc for the success rate curves were 0 736 0 748 0 827 and 0 809 for fr lsi lr and ann respectively the findings revealed that models showed promising results for shallow landslide susceptibility modelling since they all give accuracy values higher than 73 the lr and ann methods however proved to be superior in representing landslide susceptibility throughout the study area

morphology structure and kinematics of a rainfall controlled slow moving andean landslide peru the large slow moving landslide of maca is located in the upper colca valley southern peru a region characterized by a well pronounced rainy period and intense and recurrent sustained seismicity the landslide developed in deep lacustrine deposits has recently accelerated threatening the maca village this work aims at understanding the rupture mechanism and the causes of the recent landslide reactivation acceleration we present a multidisciplinary characterization of the maca landslide that includes i geological and morphological mapping in the field ii remote sensing analysis using an historical aerial photograph of 1955 and the pleiades satellite images 2013 iii global positioning system gps including time series of surveys over 13 years and continuous measurements over 14 months iv a geophysical campaign with deep electrical resistivity tomography profiles acquired across the landslide mass our study shows that this 60 mm3 landslide which can be classified as a clay silt compound landslide moved by 15 m between 2001 and 2014 with a large inter annual velocity variation up to a factor of 500 depending on the rainfall intensity we suggest that these dramatic changes in velocity are the result of the combination of a threshold mechanism and the short intense rainy season in peru this study reveals three main driving factors acting at different timescales i over several decades the river course has significantly changed causing the maca landslide reactivation in the 1980s due to the erosion of its toe ii at the year scale a minimum amount of rainfall is required to trigger the motion and this amount controls the landslide velocity iii transient changes in slide velocity may occur anytime due to earthquakes this study particularly highlights the non linear behaviour of the motion with rainfall copyright 2016 john wiley sons ltd

boninitic and low ti subduction related lavas from intraoceanic arc backarc systems and low ti ophiolites a reappraisal of their petrogenesis and original tectonic setting a comprehensive review of boninitic and other low ti subduction related lavas from modern intraoceanic arc backarc systems and of low ti ophiolites shows a complete compositional range from boninite to island arc basalts transitional low ti types distinguishable from the main magma types are well represented and defined here as 1 transitional boninites mainly from low ti ophiolites and 2 low ti island arc basalts major compatible and incompatible elements are clearly decoupled in all these low ti subduction related magmas in general their petrogenesis reflects a high degree of hydrous but not necessarily water saturated melting at pressures lower than 15 20 kbar of severely depleted mantle sources enriched in lile and h2o which are residual after the earlier extraction of basalt s as the residues after the extraction of low ti subduction related magmas very likely have a dunitic clinopyroxenefree harzburgitic composition it is proposed that the cao al2o3 ratios of the primary melts reflect those of their mantle sources particularly for the boninites and transitional boninites in this model the source of boninites sensu stricto would show a variable degree of depletion from clinopyroxene bearing to clinopyroxene free harzburgite whereas those of transitional boninites low ti island arc basalts would have clinopyroxene bearing harzburgite clinopyroxene poor lherzolite compositions the metasomatizing components involved in the genesis of low ti island arc basalts have a very close affinity with those involved with the sources of normal island arc tholeiites the common eruptive setting indicates that these low ti lavas represent extreme magma types of an otherwise normal island arc tectonomagmatic regime the petrogenesis of tertiary boninites and transitional boninites and the comparable magma types of the low ti ophiolites require at least these components 1 a variably depleted mantle source probably a subarc mantle residual after island arc basalt extraction 2 a hydrous fluid probably derived from dehydration of the subducted altered oceanic crust which carries most of sr ba k and rb in the subarc source and 3 a lree zr and nb enriched component with a low 143nd 144nd ratio probably derived from an ocean island type source it is proposed that this third component also carried significant amounts of rb and k which totally obliterated the ba spike typical of island arc tholeiites iats and produced the distinctive rb spike typical of the boninite transitional boninite magmas this component is hypothetically identified in liquids produced by partial melting of small scale large magnitude k richerite phlogopite bearing heterogeneities within the hot rising asthenospheric diapirs required in the model of crawford et al 1981 for the genesis boninite transitional boninite magmas geochemical thermal and geological constraints are best explained in a model which restricts the genesis of boninite transitional boninite magmas to the early stages of intraoceanic interarc spreading and to important rifting phases of the arc and or early interarc basin structures connected with hot rising asthenospheric mantle diapirs

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

active movement of the cascade landslide complex in washington from a coherence based insar time series method abstract we used interferometric synthetic aperture radar insar data from the alos 1 satellite to investigate the active movement of landslides along the columbia river gorge from 2007 2011 to increase the spatial extent of the deformation signal we developed a coherence based small baseline subset sbas method and derived the time series of the landslide movement we find no significant movement on the previously mapped washougal sakamania oregon shore and wind mountain landslides however we document the slow movement of the redbluff landslide which is part of the cascade landslide complex the insar data reveal up to approximately 25 cm of line of sight displacement over the 4 year observation period the redbluff landslide is seasonally activated with accelerated movement observed during the early winter of each year the amplitude of the seasonal signal is variable from year to year with the greatest movement observed in early winter of 2009 and 2011 to assess the triggering mechanisms we compared the displacement time series data with local precipitation data the deformation correlated well with precipitation implying the slow movement is controlled by rainfall that infiltrates to the base of the slide

runoff and soil loss characteristics on loess slopes covered with aeolian sand layers of different thicknesses under simulated rainfall abstract in the wind water erosion crisscross region of the northern loess plateau parts of loess slopes have been covered by layers of aeolian sand of different thicknesses knowledge of soil erosion processes and magnitudes on these slopes is essential to understanding the coupled water wind erosion processes and to address the resulting downstream coarse sediment problems in the yellow river simulated rainfall intensity 90 mm h 1 was performed to explore the effects of sand layer thickness on runoff and soil loss from loess slopes covered with different sand layer thicknesses 0 0 5 2 5 10 15 20 and 25 cm initial runoff time increased with increasing sand layer thickness with greater changes occurring for the increases in the thinner 0 5 cm than for the thicker layers 5 25 cm total runoff yield from the sand covered loess slopes was 18 55 lower than from the uncovered loess slope and decreased with increasing sand layer thickness in contrast total sediment yield was up to 14 times greater from the sand covered loess slopes than from the uncovered loess slope and rapidly increased with increasing sand layer thickness during the rainstorm runoff and soil loss rates exhibited unimodal distributions and they were related by a positive linear function both before and after the maximum soil loss rate that had a high determination coefficient r2 0 8 p

a comparative analysis of terrain stability models for predicting shallow landslides in colluvial soils abstract most of the slopes of the hilly areas of the apennines are composed of colluvial soils originating from the weathering of the bedrock and down slope transportation shallow slides affect this superficial cover depend largely on the surface topography and are a recurrent problem sinmap and shalstab are terrain stability models that combine steady state hydrology assumptions with the infinite slope stability model to quantify shallow slope stability they have a similar physical basis but they use different indices to quantify instability the purposes of this study are to test and compare the approaches of sinmap and shalstab models for slope stability analysis and to compare the results of these analyses with the locations of the shallow landslides that occurred on november 2002 in an area of the oltrepo pavese northern apennines the territory of s giuletta characterized by clayey silty colluvial soils represents the test site the digital elevation model was constructed from a 1 5000 scale contour map and was used to estimate the slope of the terrain as well as the potential soil moisture conditions in situ and laboratory tests provided the basis for measuring values for soil hydraulic and geotechnical parameters moisture content soil suction atterberg limits methylene blue dye adsorption hydraulic conductivity soil thickness was extracted from a soil database an inventory of landslide from interpretation of aerial photographs and field surveys was used to document sites of instability mostly soil slips and to provide a test of model performance by comparing observed landslide locations with model predictions the study discusses the practical advantages and limitations of the two models in connection with the geological characteristics of the studied area which could be representative of similar geological contexts in the apennines

occurrence of landsliding on slopes where flowsliding had previously occurred an investigation in a loess platform north west china abstract loess slides in south jingyang platform shaanxi province usually occur on slopes where loess flowslides had previously occurred numerical modeling shows that flowslide occurrence causes conditions that increase shear stress and water content in the subsequent slopes both of these factors move the soil stress states towards its theoretical failure line under these conditions only small increases in water content can cause soil collapse this leads to the backscarps of former flowslides being much more prone to landsliding wetting test results show that the loess can collapse suddenly as the water content gradually increases therefore the wetting process induced by continued irrigation may result in the subsequent slides during constant water content tests of the loess material soil shear strength increases with the development of specimen deformation therefore slide mobilization which may be a relatively slow process is dependent on whether the wetting conditions exist finally a slope evolution model for loess platforms is proposed in this study

infiltration analysis to evaluate the surficial stability of two layered slopes considering rainfall characteristics abstract shallow slope failures in residual soil during periods of prolonged infiltration are common throughout the world using a one dimensional infiltration model and an infinite slope analysis this study examines an approximate method of determining how infiltration influences the surficial stability of two layered slopes the method extends moore s infiltration model which is based on the green ampt model to cover more general situations including those where water moves upward from a perched water table in decreasingly permeable soil the method has also been used to evaluate the likelihood of a shallow slope failure being induced by a particular rainfall event in making this evaluation the method takes into accounts the rainfall intensity and duration of various return periods in a two layered soil profile a comparison of the results of the infiltration model with the results of numerical analyses shows that with the use of properly estimated input parameters the proposed model compares reasonably well with other model that rely on more rigorous finite element method