wildfire disturbance and shallow landsliding in coastal british columbia over millennial time scales a numerical modelling study an algorithm for wildfire occurrence is introduced for incorporation into a numerical model of drainage basin evolution within the model fire return intervals are determined using a stochastic rule set and fire sizes are assigned according to a pareto distribution a weibull distribution was fit to millennial scale lake charcoal data for calibration of fire return intervals in this study while data for the olympic peninsula were used to determine the fire size distribution loss of tree root strength resulting from stand replacing wildfires has been found to be comparable to loss after timber harvesting hence data for increased shallow landslide activity associated with logging were used to calibrate transport equations for years following wildfire incidence a weathering relation is incorporated in the model which drives the supply of sediment when sediment supply is depleted in the model the shallow landsliding module shuts off until new material is available for transport time since last fire analysis indicates that the weibull parameters defined for the clayoquot charcoal data produce results that are weighted too heavily towards recent fires sensitivity analysis was undertaken suggesting alternative values may be more reasonable for further model runs the introduction of a weighted probability factor for aspect whereby south facing slopes have a higher likelihood of fire initiation was not found to significantly affect patterns of fire age in the landscape patterns of net topographic change after 6000 years of model run time indicate that greatest net erosion is found on steep upper slopes with the highest deposition occurring in hillslope hollows and low order channels depositional grid cells in interfluves show a variable response to the inclusion of wildfire in the model net erosion occurs over a relatively low proportion of hillslope area with wildfire model runs showing a strong erosional signal in these locations for stream grid cells the additional deposition due to the inclusion of wildfire in model runs is about 9 10 for 1st to 3rd order streams overall deposition rates increase with decreasing stream order reflecting greater hillslope channel coupling in low order streams

scale invariance of soil moisture variability and its implications for the frequency size distribution of landslides abstract power spectral analyses of soil moisture variability are carried out from scales of 100 m to 10 km on the microwave remotely sensed data from the washita experimental watershed during 1992 the power spectrum s k has an approximate power law dependence on wave number k with the exponent 1 8 this behavior is consistent with the behavior of a stochastic differential equation for soil moisture at a point and it has important consequences for the frequency size distribution of landslides we present the cumulative frequency size distributions of landslides induced by precipitation in japan and bolivia as well as landslides triggered by the 1994 northridge california earthquake large landslides in these regions despite being triggered by different mechanisms have a cumulative frequency size distribution with a power law dependence on area with an exponent ranging from 1 5 to 2 we use a soil moisture field with the above statistics in conjunction with a slope stability analysis to model the frequency size distribution of landslides in our model landslides occur when a threshold shear stress dependent on cohesion pore pressure internal friction and slope angle is exceeded this implies a threshold dependence on soil moisture and slope angle since cohesion pore pressure and internal friction are primarily dependent on soil moisture the cumulative frequency size distribution of domains of shear stress greater than a threshold value with soil moisture modeled as above and topography modeled as a brownian walk is a power law function of area with an exponent of 1 8 for large landslide areas this distribution is similar to that observed for landslides the effect of strong ground motion from earthquakes lowers the shear stress necessary for failure but does not change the frequency size distribution of failed areas this is consistent with observations this work suggests that remote sensing of soil moisture can be of great importance in monitoring landslide hazards and proposes a specific quantitative model for landslide hazard assessment

analysis of landslide frequencies and characteristics in a natural system coastal british columbia two hundred and one debris slides and debris ows were analyzed in a 286 km2 study area on the west coast of vancouver island british columbia canada the study area remains essentially untouched by humans and therefore affords a natural setting in which to examine slope processes landslides were identi ed and characterized on aerial photographs from 1 15 000 to 1 31 680 and were then mapped and transferred to a gis for analysis based on detailed landslide surveys we propose a new method to accurately determine volume of landslides of this type by measured total area results indicate average denudation rates of 56 m3 y 1 km 2 and higher natural rates of failure than analogous regions in coastal british columbia in contrast the landslide rates are substantially less than those from forested watersheds landslide distribution is spatially clustered in air photograph epochs and we propose intense storm cells within regional events as the causal mechanism further failures occurred preferentially over the west coast crystalline complex by 1 4 times a metamorphic assemblage of gabbros schists and amphibolites but 1 5 times less often over the island plutonic suite a granitic intrusive formation the former result represents a new nding while the latter corroborates ndings of previous authors we examined magnitude frequency relationships of the data set and present for the rst time a strong argument that the rollover effect is not merely an artefact but is instead a consequence of the physical characteristics of the landslides themselves we subsequently analyzed magnitude frequency relationships from two other complete data sets from coastal british columbia and produced a family of curves corroborating this result copyright 2004 john wiley sons ltd

impact of the 2008 wenchuan earthquake in china on subsequent long term debris flow activities in the epicentral area abstract the 2008 wenchuan earthquake triggered the largest number of landslides among the recent strong earthquake events around the world the loose landslide materials were retained on steep terrains and deep gullies in the period from 2008 to 2015 numerous debris flows occurred during rainstorms along the provincial road 303 pr303 near the epicentre of the earthquake causing serious damage to the reconstructed highway approximately 5 24 10 6 m 3 of debris flow sediment was deposited shortly after the earthquake this paper evaluates the evolution of the debris flows that occurred after the wenchuan earthquake which helps understand long term landscape evolution and cascading effects in regions impacted by mega earthquakes with the aid of a gis platform combined with field investigations we continuously tracked movements of the loose deposit materials in all the debris flow gullies along an 18 km reach of pr303 and the characteristics of the regional debris flows during several storms in the past seven years this paper presents five important aspects of the evolution of debris flows 1 supply of debris flow materials 2 triggering rainfall 3 initiation mechanisms and types of debris flows 4 runout characteristics and 5 elevated riverbed due to the deposited materials from the debris flows the hillslope soil deposits gradually evolved into channel deposits and the solid materials in the channels moved towards the ravine mouth accordingly channelized debris flows became dominant gradually due to the decreasing source material volume and changes in debris flow characteristics the triggering rainfall tends to increase from 30 mm h 1 in 2008 to 64 mm h 1 in 2013 and the runout distance tends to decrease over time the runout materials blocked the river and elevated the riverbed by at least 30 m in parts of the study area the changes in the post seismic debris flow activity can be categorized into three stages i e active unstable and recession

late quaternary sea levels and crustal movements coastal british columbia late quaternary sea level fluctuations on the british columbia coast have been established from studies of terrestrial and marine sediments and landforms these studies indicate that the sea level history of mainland british columbia and eastern vancouver island is very different from that of the queen charlotte islands and western vancouver island specifically in the former areas there was a rapid rise of submerged coastal lowlands between about 13 000 and 10 000 years ago emergence culminated about 6000 9000 years ago depending on the locality when the sea relative to the land was 12 m or more lower than at present in some areas during middle and late holocene time relative sea level rose on the mainland coast and at least locally on eastern vancouver island resulting in inundation of coastal archaeological sites and low lying terrestrial vegetation tidal records and precise levelling suggest ongoing submergence of at least part of this region in contrast shorelines on the queen charlotte i

estimates of three dimensional rupture surface geometry of deep seated landslides using landslide inventories and high resolution topographic data abstract deep seated landslides cause significant damage to the built environment characterizing the shear surface and volume of these features is often limited to intensive site specific monitoring or at a larger scale generalized empirical relationships developed from change analysis however there is limited means of generalizing regional scale rupture surface information for deep seated landslides where deposits still overlay much of the failure surface herein a method is proposed that uses high resolution bare earth digital elevation models with an inventory of mapped landslide extents to gather first order estimates of three dimensional rupture surface geometries and volumes for rotational and compound landslide features at a regional scale this approach is first calibrated to a suite of well characterized landslides and then applied to over eight hundred deep seated landslides in three different geologic regimes estimates of landslide area volume relationships are proposed that are consistent with previous empirical assessments the aforementioned relationships describe mean landslide thickness added relationships relating landslide area to maximum landslide thickness are proposed the presented results suggest limits on magnitudes of depth with landslide classification and relief between geologic settings consistent with prior research it is observed that landslide area exhibits a first order control on maximum and mean landslide thickness but further insight is provided towards the influence of a limited set of landslide classification which exhibit controls on the range of magnitudes observed for maximum landslide depth associated with failure lastly the implications and limitations of the developed three dimensional mapping approach is discussed

equatorial subthermocline currents across the pacific recent sections crossing the equator at nine longitudes from 146 e to 86 w show zonal currents below 400 m similar to those found in a 16 month mean section on 159 w from the pacific equatorial ocean dynamics pequod program in 1982 1983 most of the new measurements were made with a lowered acoustic doppler current profiler eastward current extrema north and south intermediate countercurrents are found in all sections about 2 from the equator in the depth range 500 1500 m with the possible exceptions of 146 e where topography complicates the picture south of the equator and 150 e where the sections extend only from 1 s to 2 n poleward of the intermediate countercurrents westward flow is found near 3 from the equator in most of the sections on the equator from 250 500 m depth a westward equatorial intermediate current is found in many but not all of the sections similarly it is present in the pequod mean but not in all synoptic sections below the intermediate currents and countercurrents an eastward current near 3000 m was found at and south of the equator in the pequod mean and in the new sections from 150 e to 110 w near 4000 m there is westward flow south of the equator in the pequod mean and near the equator in the new sections from 179 e to 135 w geostrophic currents calculated from an 8 year mean hydrographic section at 165 e also resemble the pequod mean although not conclusive the evidence presented here indicates that these currents are basin scale components of the general circulation perhaps involving vigorous horizontal recirculation in a set of basin wide elongated gyres within a few degrees of the equator

zonal jets in the equatorial atlantic ocean abstract we use position data from argo floats smoothed out over 400 km 200 km zonal ellipses and interpolated onto a 0 5 grid to investigate the zonal jet structure of the flow field at the sea surface and on three subsurface layers central waters cw 200 m antarctic intermediate waters aaiw 1000 m upper north atlantic deep waters unadw 1500 m in the equatorial atlantic ocean 15 s to 15 n the annual mean fields exhibit narrow zonal jets typically 4 5 wide at the sea surface and only 2 at the subsurface levels with directions alternating in latitude and maximum speeds about 0 5 m s 1 at the surface 0 1 m s 1 at cw and unadw and 0 03 m s 1 at aaiw the available data also allows us to explore the seasonal variability of these jets at the surface and aaiw levels the surface currents are dominated by an annual cycle between 4 n and 10 n and to a lesser degree by a semi annual contribution close to the equator this variability is an outcome of evolving zonal recirculations with the north equatorial countercurrent necc arising from the diversion of the northern branch of the south equatorial current nsec the diversion begins in the eastern atlantic and propagates west between april and august following the inter tropical convergence zone itcz the aaiw current field is largely affected by westward propagating anomalies most visible near 3 s 0 3 n and 7 n which give rise to current reversals annual averaging produces the illusion of more 5 instead of 3 and slower peak values about 0 03 m s 1 instead of 0 1 m s 1 jets than found on any month

supply and removal of sediment in a landslide dominated mountain belt central range taiwan abstract a strong coupling between hillslope and valley systems is often inferred for mountain landscapes dominated by bedrock landsliding we reveal the nature of this link using data sets on landsliding and sediment transport from two montane catchments draining the eastern central range of taiwan here the magnitude frequency distribution of landslides can be modeled by a robust power law but this scale invariance is not mirrored in the sediment discharge at the mountain front instead downstream sediment loads reflect a complex response to both sediment supply and ambient hydraulic conditions the rivers do not transport significant amounts of sediment unless it is provided by hillslope mass wasting in the catchment removal of landslide debris is a function of the transport capacity of the stream at the site of entry thus there is a dual supply and transport control on sediment loads in bedrock floored streams over a monitoring period of 25 yr the bulk of the sediment leaving the mountain bel

postglacial topographic evolution of glaciated valleys a stochastic landscape evolution model the retreat of valley glaciers has a dramatic effect on the stability of glaciated valleys and exerts a prolonged influence on the subsequent fluvial sediment transport regime we have studied the evolution of an idealized glaciated valley during the period following retreat of ice using a numerical model the model incorporates a stochastic process to represent deepseated landsliding non linear diffusion to represent shallow landsliding and an approximation of the bagnold relation to represent fluvial sediment transport it was calibrated using field data from several recent surveys within british columbia canada we present ensemble model results and compare them with results from a deterministic linear diffusion model to show that explicit representation of large landslides is necessary to reproduce the morphology and channel network structure of a typical postglacial valley our model predicts a rapid rate of fluvial sediment transport following deglaciation with a subsequent gradual decline similar to that inferred for holocene time we also describe how changes in the model parameters affect the estimated magnitude and duration of the paraglacial sediment pulse

sediment transfer by shallow landsliding in the queen charlotte islands british columbia despite the importance of landsliding in routing sediment through mountainous drainage basins few studies have documented landsliding rates over extended time and space scales we have investigated landsliding in surficial material in the queen charlotte islands using a large inventory of events derived from aerial photography covering an area of 166 7 km 2 the mean erosion rate for shallow landsliding is 0 10 mm a 1 which is at the upper end of shallow landsliding rates observed in the pacific northwest and coastal british columbia but several orders of magnitude lower than rock based landsliding rates reported in the literature probability distributions for landslide area and volume are somewhat convex in form flattening of the curve found at low magnitudes may be due to sampling bias or physical mechanisms inhibiting failure and the steepening for high values may exist because the sampling period is not long enough to adequately represent large events landslides generally initiate on hillslope gradients greater than 0 50 0 60 the largest numbers of landslides occur on south to southwest facing slopes and east to northeast facing slopes most events occur on concave and straight hillslopes in upper slope positions landsliding rates were found not to be af fected by rock type hillslopes in the queen charlotte islands are often mantled by weathered quaternary deposits and hence landsliding events are not directly controlled by weathering of bedrock about 31 of landslides identified in this study deposited material in stream reaches with about 83 of these landslides deposited in reaches with gradients between 3 and 10 resume malgre la grande contribution des glissements de terrain a acheminer des sediments a travers des bassins de drainage montagneux peu d etudes ont documente les taux de glissements de terrain sur une longue periode de temps et sur de grandes superficies nous avons fait des recherches sur des glissements de materiaux de surface dans les iles de la reine charlotte en utilisant un grand inventaire d evenements tires de photographies aeriennes couvrant une re

modelling landslide hazard soil redistribution and sediment yield of landslides on the ugandan footslopes of mount elgon in this study the lapsus ls landslide model together with a digital terrain analysis of topographic attributes is used as a spatially explicit tool to simulate recent shallow landslides in manjiya county on the ugandan slopes of mount elgon manjiya county is a densely populated mountainous area where landslides have been reported since the beginning of the twentieth century to better understand the causal factors of landsliding 81 recent landslides have been mapped and investigated through statistical analysis it was shown that steep concave slopes high rainfall soil properties and layering as well as human interference were the main factors responsible for landslides in the study area lapsus ls is used to construct a landslide hazard map and to confirm or reject the main factors for landsliding in the area the model is specifically designed for the analysis of shallow landslide hazard by combining a steady state hydrologic model with a deterministic infinite slope stability model in addition soil redistribution algorithms can be applied whereby erosion and sedimentation by landsliding can be visualized and quantified by applying a threshold critical rainfall scenario the model is tested in the manjiya study area for its ability to delineate zones that are prone to shallow landsliding in general and to group the recent landslides into a specific landslide hazard category the digital terrain analysis confirms most of the causal topographic factors for shallow landsliding in the study area in general shallow landslides occur at a relatively large distance from the water divide on the transition between steep concave and more gentle convex slope positions which points to concentration of sub surface flow as the main hydrological triggering mechanism in addition lapsus ls is capable to group the recent shallow landslides in a specific landslide hazard class critical rainfall values of 0 03 0 05 m day 1 by constructing a landslide hazard map and simulating future landslide scenarios with the model slopes in manjiya county can be identified as inherently unstable and volumes of soil redistribution can yield four times higher than currently observed more than half of this quantity can end up in the stream network possibly damming rivers and causing major damage to infrastructure or siltation and pollution of streams the combination of a high population density land shortage and a high vulnerability to landslides will likely continue to create a major sustainability problem 2007 elsevier b v all rights reserved

the role of the sediment budget in understanding debris flow susceptibility this study proposes a sediment budget model to predict the temporal variation of debris volume stored in a debris flow prone watershed the sediment budget is dominated by shallow landslides and debris outflow the basin topography and the debris volume stored in the source area of the debris flow prone watershed help evaluating its debris flow susceptibility the susceptibility model is applied to the tungshih area of central western taiwan the importance of the debris volume in predicting debris flow susceptibility is reflected in the standardized coefficients of the proposed statistical discriminant model the high prediction rate 0 874 for the occurrence of debris flows justifies the capability of the proposed susceptibility models to predict the occurrence of debris flows this model is then used to evaluate the temporal evolution of the debris flow susceptibility index the analysis results show that the numbers of watershed which are classified as a debris flow group correspond well to storage of sediment at different time periods these numbers are 10 before the occurrence of chi chi earthquake 13 after the occurrence of chi chi earthquake 16 after the occurrence of landslides induced by typhoon mindulle typhoon m and 14 after the occurrence of debris flows induced by typhoon m it indicates that the occurrence of 7 6 chi chi earthquake had significant impact on the debris flow occurrence during subsequent typhoons copyright 2009 john wiley sons ltd

oxygen tongues and zonal currents in the equatorial atlantic 1 equatorial zonal currents and associated oxygen distributions are studied using shipboard hydrographic data trajectories from isopycnic floats drifting at about 300 m depth and velocity time series from the upper 1100 m obtained at two equatorial moorings located at 35 w and 23 w mean profiles of zonal velocity measured by moored acoustic doppler current profilers yielded a westward flowing equatorial intermediate current eic below the equatorial undercurrent euc at both locations the eic consists of two westward current cores at about 250 and 450 m the upper core of the eic deepens by about 30 m from 23 w where it has a mean velocity of 6 2 cm s 1 to 35 w where the mean is 5 3 cm s 1 the lower core of the eic is about twice as strong with 12 1 cm s 1 at 23 w and 9 2 cm s 1 at 35 w the flow below the euc is characterized by substantial interannual variability from may to december 2005 a strong zonally coherent eastward jet occurred at 300 to 350 m depth found to be an expression of shallow stacked jets superimposed on the mean eic shipboard hydrographic observations in june july 2006 revealed the existence of a high oxygen tongue that can be traced from 35 w to 10 w in the depth range of the eastward jet prevailing during the preceding year on the basis of an advection diffusion balance it is suggested that the oxygen decrease from 35 w to 10 w within the oxygen tongue is mainly balanced by lateral eddy diffusivity and oxygen consumption with diapycnal turbulent diffusivity playing only a minor role

microstructure and porosity evolution during experimental carbonation of a natural peridotite abstract carbonation experiments t 100 200 c pco2 14 6 19 4 mpa were performed under closed system conditions on a natural peridotite from almklovdalen w norway to investigate the microstructure and porosity evolution as a function of reaction progress the unreacted samples cubes of 2 5 3 cm3 were composed mainly of forsteritic olivine 80 90 vol clinochlore orthopyroxene amphibole and chromite initial porosities were on the order of 6 8 due to the presence of abundant inter and intragranular microfractures microstructural observations after 7 42 days of experimental treatment showed that olivine was by far the most reactive phase after 7 days at 100 c no carbonate products were formed but longer reaction times produced small amounts of magnesite on the surface and within the fracture network of the peridotite cubes increasing temperatures led to faster reactions and pore space filling by magnesite in addition replacement rims up to 50 m thick composed of magnesite and amorphous silica formed around individual olivine grains the replacement began with the formation of an amorphous silica layer that retained the shapes of the initial olivine grains this layer remained permeable during the reaction as it allowed further dissolution of the underlying olivine increasing extents of carbonation were accompanied by decreasing porosities and enhanced cementation of grain boundaries about 50 of the initial porosity was closed when carbonation reached about 10 the reacted samples showed no evidence of reaction induced cracking indicating that the carbonation reaction was self limiting in our experiments these results may have important implications for the efficiency of in situ co2 sequestration in peridotites

sediment generation and delivery from large historic landslides in the southern alps new zealand abstract there is much variability of sediment yield in mountain river systems because it is influenced by both periodic e g snowmelt monsoonal circulation and episodic high intensity rainstorms earthquakes controls in the southern alps of new zealand landslides are dominant mechanisms of conveying large amounts of debris to river channels this paper attempts to quantify catastrophic modes of sediment delivery by presenting three recent examples of large landslides on the western slopes of the southern alps a combination of ground surveys dem based volume calculations and air photo interpretation attributes immediate postfailure sediment yields in excess of 70 000 t km 2 a 1 in the short term such landslide derived sediment pulses pose significant hazards to downstream settlements and infrastructure on alluvial fans where they cause massive aggradation increased flooding frequency and large scale channel avulsion in addition to intramontane valley floor obliteration or channel metamorphosis these geomorphic impacts may thus occur far beyond the initial locations of slope failure these catastrophic off site effects involve apparent net sediment delivery rates in the order of 10 5 10 6 m 3 a 1 the accurate quantification of the relative contribution of debris from the disturbing landslide to overall sediment flux is extremely difficult nonetheless are quantitative estimates of landslide derived sediment production and delivery important data to develop a more comprehensive understanding of the variability in alpine sediment flux such data are essential not only for use in hydraulic engineering or catchment management but also in gauging potential future impacts from rainstorm and earthquake induced landsliding in the southern alps

tectonic significance of holocene marine terraces in the coastal range eastern taiwan abstract well developed marine terraces on the coast of eastern taiwan between chengkung and hualien can be divided into three morphotectonic sectors 1 i chengkung kueian 2 ii shuilien and its vicinity 3 iii north of shuilien sector i displays at least five terrace levels and has undergone northward tilting and uplift the available 234 u 230 th and 14 c ages suggest that one of its holocene terraces rises to about 40 m and locally to 70 m above msl the average uplift rate for the holocene in this sector decreases northward from 9 10 mm yr to about 2 3 mm yr few traces of former shorelines or marine terraces higher than 5 m are found in sector ii north of shuilien in sector iii terrace elevation increases gradually and indicates an uplift rate of about 2 3 mm yr the uplift pattern agrees with geodetic data obtained between 1985 and 1988 the high uplift rates in sector i may represent compression and shortening of the northwestern corner of the philippine sea plate the low rates in sector ii may correlate with the region where the ryukyu trench meets the eastern coast of taiwan

reconstructing high magnitude low frequency landslide events based on soil redistribution modelling and a late holocene sediment record from new zealand a sediment record is used in combination with shallow landslide soil redistribution and sediment yield modelling to reconstruct the incidence of high magnitude low frequency landslide events in the upper part of a catchment and the history of a wetland in the lower part eleven sediment cores were obtained from a dune impounded wetland at te henga west auckland northern new zealand sediment stratigraphy and chronology were interpreted by radiocarbon dating foraminiferal analysis and provisional tephrochronology gradual impoundment of the wetland began c 6000 cal yr bp coinciding with the start of a gentle sea level fall but complete damming and initial sedimentation did not begin until c 1000 cal yr bp after damming four well defined sediment pulses occurred and these are preserved in the form of distinct clay layers in most of the sediment cores for interpreting the sediment pulses a physically based landslide model was used to determine spatially distributed relative landslide hazard applicable at the catchment scale an empirical landslide soil redistribution component was added and proved able to determine the volumes and spatial pattern of eroded and deposited soil material sediment delivery ratio and the impact on total catchment sediment yield sediment volumes were calculated from the wetland cores and corresponding landslide scenarios are defined through back analysis of modelled sediment yield output in general at least four major high magnitude landslide events both natural and intensified by forest clearance activities occurred in the catchment upstream of te henga wetland during the last c 1000 years the spatial distribution of modelled critical rainfall values for the catchment can be interpreted as an expression of shallow landslide hazard the magnitude of the sediment pulses represented in the wetland can be back calculated to critical rainfall thresholds representing a shallow landslide model scenario

the effects of slope length and slope gradient on the size distributions of loess slides field observations and simulations abstract in this study we characterize and consider the effects of slope length and slope gradient on the size distributions of loess slides to carry out this study we employ data on 275 loess slides within zhidan county central loess plateau china these data were collected in the field and supplemented by the interpretation of remote sensing images both the field observations and slope stability analysis show that loess slide size increases with the slope length slide sizes is significantly correlated with slope length showing a power law relationship in both cases however the simulation results show that slope gradient is not associated with loess slide size the main part of the link between slope gradient and slide size seen in the observations is only apparent as indicated by the strong connection between slope gradient and length statistical analysis of the field observations reveals that slope gradient decreases with increasing slope length and this correlation interferes with the potential relationship between landslide sizes and slope gradient seen in the field observations in addition the probability densities of the areas of loess slides occurring on slopes of different slope lengths are determined using kernel density estimation this analysis shows that slope length controls the rollover of the frequency size distribution of loess slides the scaling exponent increases with slope length

the role of topography in the scaling distribution of landslide areas a cellular automata modeling approach abstract power law scaling has been widely observed in the frequency distribution of landslide sizes the exponent of the power law characterizes the probability of landslide magnitudes and it thus represents an important parameter for hazard assessment the reason for the universal scaling behavior of landslides is still debated and the role of topography has been explored in terms of possible explanation for this type of behavior we built a simple cellular automata model to investigate this issue as well as the relationships between the scaling properties of landslide areas and the changes suffered by the topographic surface affected by landslides the dynamics of the model is controlled by a temporal rate of weakening which drives the system to instability and by topography which defines both the quantity of the displaced mass and the direction of the movement results show that the model is capable of reproducing the scaling behavior of real landslide areas and suggest that topography is a good candidate to explain their scale invariance in the model the values of the scaling exponents depend on how fast the system is driven to instability they are less sensitive to the duration of the driving rate thus suggesting that the probability of landslide areas could depend on the intensity of the triggering mechanism rather than on its duration and on the topographic setting of the area topography preserves the information concerning the statistical distribution of areas of landslides caused by a driving mechanism of given intensity and duration

magnitude frequency characteristics and preparatory factors for spatial debris slide distribution in the northern faroe islands abstract the faroe islands in the north atlantic ocean are highly susceptible to debris avalanches and debris flows originating from debris slide activity in shallow colluvial soils to provide data for hazard and risk assessment of debris avalanches and debris flows this study aims at quantifying the magnitude and frequency of their debris slide origins as well as identifying which preparatory factors are responsible for the spatial debris slide distribution in the landscape for that purpose a debris slide inventory was generated from aerial photo interpretation api fieldwork and anecdotal sources covering a 159 km2 study area in the northern faroe islands a magnitude cumulative frequency mcf curve was derived to predict magnitude dependant debris slide frequencies while preparatory factors responsible for spatial debris slide distribution were quantified through gis supported discriminant function analysis dfa nine factors containing geological lithology dip geomorphological slope angle altitude aspect plan and profile curvature and land use infield outfield sheep density information were included in the multivariate analysis debris slides larger than 100 m2 with magnitude expressed as topographic scar area can be predicted from the power law function y 936 26x 1 277 r2 0 98 while a physical explanation is preferred for the roll over pattern of smaller slope failures the dfa is able to correctly classify app 70 of the modeled terrain units into their pre determined stable unstable groups preparatory factors responsible for the spatial debris slide distribution are aspect slope angle sheep density plan curvature and altitude while influence of the remaining factors is negligible

a review of methods used to estimate initial landslide failure surface depths and volumes abstract this paper presents an overview of existing methods developed to characterize initial landslide failure surfaces and compute volumes based on surface information when it is buried this paper reviews the simplest models such as volume estimation based on ellipsoids and the information that can be obtained from surface displacement and morphology a simple method to define the volume of a rockslide using the identified discontinuities is also outlined the sloping local base level slbl which is able to automatically obtain a possible failure surface on the basis of a digital elevation model dem is described the balanced cross section methods applied to landslides are illustrated and can give the depth of the failure surface using predefined assumptions such as vector displacement parallel to the failure surface we can obtain an approximation of the failure surface either along translational or circular slides and this method can be improved by adding a mass balance equation recent work has also shown that using an inverse model a mass balance equation and assumptions about the rheology enables estimation of the failure surface these methods are illustrated with examples and they are applied to case studies and compared when the data available makes it possible the advantages and disadvantages of the methods are discussed this paper shows that the use high resolution topography and interpretation of the morphology is underexploited to extract information about failure surfaces geometry

forecasting the magnitude of potential landslides based on insar techniques abstract a new method combining empirical modeling with time series interferometric synthetic aperture radar insar data is proposed to provide an assessment of potential landslide volume and area the method was developed to evaluate potential landslides in the heitai river terrace of the yellow river in central gansu province china the elevated terrace has a substantial loess cover and along the terrace edges many landslides have been triggered by gradually rising groundwater levels following continuous irrigation since 1968 these landslides can have significant impact on communities affecting lives and livelihoods developing effective landslide risk management requires better understanding of potential landslide magnitude fifty mapped landslides were used to construct an empirical power law relationship linking landslide area al to volume vl vl 0 333 al1 399 insar derived ground displacement ranges from 64 mm y to 24 mm y along line of sight los further interpretation of patterns based on remote sensing insar optical image and field survey enabled the identification of an additional 54 potential landslides 1 9 102 m2 al 8 1 104 m2 in turn this enabled construction of a map that shows the magnitude of potential landslide activity this research provides significant further scientific insights to inform landslide hazard and risk management in a context of ongoing landscape evolution it also provides further evidence that this methodology can be used to quantify the magnitude of potential landslides and thus contribute essential information towards landslide risk management

influence of the barotropic mean flow on the width and the structure of the atlantic equatorial deep jets a representation of an equatorial basin mode excited in a shallow water model for a single high order baroclinic vertical normal mode is used as a simple model for the equatorial deep jets the model is linearized about both a state of rest and a barotropic mean flow corresponding to the observed atlantic equatorial intermediate current system we found that the eastward mean flow associated with the north and south intermediate counter currents nicc and sicc respectively effectively shields the equator from off equatorial rossby waves the westward propagation of these waves is blocked and focusing on the equator due to beta dispersion is prevented this leads to less energetic jets along the equator on the other hand the westward barotropic mean flow along the equator reduces the gradient of absolute vorticity and hence widens the cross equatorial structure of the basin mode increasing lateral viscosity predominantly affects the width of the basin modes kelvin wave component in the presence of the mean flow while the rossby wave is confined by the flanking nicc and sicc independent of the presence of the mean flow the application of sufficient lateral mixing also hinders the focusing of off equatorial rossby waves which is hence an unlikely feature of a low frequency basin mode in the real ocean

deep velocity measurements in the western equatorial indian ocean abstract vertical profiles of horizontal current collected in april and june 1979 in the western indian ocean revealed the presence of short vertical scale 150 300 m deep zonal jets trapped to within 1 of the equator meridional velocity records displayed in general higher temporal and spatial variability and significantly less energy at the larger vertical scales as compared with zonal records vertical wavenumber spectra of velocity showed no statistically significant peaks the conspicuous alternating zonal jets were identified with the slightly more energetic as compared to background levels 500 429 stretched meter sm wavelengths for most vertical wavenumbers zonal currents were not significantly coherent at distances greater than 400 km downstream at shorter zonal separations phase lags were indistinguishable from zero on the equator there is an indication of upward shift of approximately 100 sm over the 500 429 sm band also on the equator zonal current u and vertical displacement

complex mass wasting response of drainage basins to forest management in coastal british columbia the impacts of logging activities on mass wasting were examined in five watersheds in the coastal mountains of british columbia historical aerial photos were used to document mass wasting events and their occurrence was related to logging activities in the study basins logged and forested areas were compared in terms of mass wasting magnitude and frequency with reference to site characteristics the recovery time of the landscape after logging was assessed bedrock type and basin physiography had no identifiable effect on mass wasting frequency and magnitude mass wasting failure was primarily controlled by slope gradient basin vulnerability increased following clearcutting relative to forested areas in that mass wasting was initiated on gentler slopes the volume of sediment produced from logged slopes is of the same order as that from forested areas which are steeper by as much as 10 in both logged and forested areas the size distribution of mass wasting events follows an exponential distribution however the variability in mass wasting size in forested areas is much higher than that obtained for logged areas the recovery time after forest harvesting is over 20 years which confirms published estimates based on vegetation reestablishment continuous disturbance of the basin however may extend the recovery time for the whole basin well beyond 20 years

lateral geomorphic connectivity in a fluvial landscape system unraveling the role of confinement biogeomorphic interactions and glacial legacies abstract the rates at which sediment from the landscape is recruited to channel networks reflect lateral geomorphic connectivity and have significant implications for biophysical river systems by strongly influencing sediment supply regime such inputs control the dynamics and characteristics of the channel as well as the associated habitat and biota the main objective of this research was to disentangle the relative importance of geomorphic and biological factors which define spatial patterns in lateral connectivity by promoting or restricting bank erosion avulsions and slope failures focusing on a forested formerly glaciated mountain basin in the interior pacific northwest we combined extensive field surveys with remote sensing data lidar aerial imagery to obtain metrics representing this complex suite of landscape characteristics the interpretation of evidence yielded by correlations between these variables a regime model and qualitative observations suggest that at a multi decadal timescale between major landscape disturbances lateral connectivity patterns in sullivan creek may be to a large extent governed by a combination of biotic factors and glacial legacies in particular forest canopy metrics were key predictors of hillslope stability as well as bank and valley floor resistance suggesting a pivotal influence of root reinforcement on the other hand instream large wood abundance was closely related to channel splitting which reflects its role in promoting channel avulsions more extensive bank erosion in reaches dominated by drift deposits appeared to indicate glacial legacies furthermore a strong association between bank erosion and colluvial inputs suggested a close coupling within the channel hillslope system lateral confinement defined as the proportion of the channel length abutting against bedrock terraces fans and roads was negatively associated with channel braiding the relationships linking confinement with bank erosion and the magnitude of colluvial inputs negative and positive association respectively were relatively weak taken together findings emerging from this research suggest that better understanding of lateral geomorphic connectivity patterns in mountain river basins similar to our study site requires that both channel processes and broader biophysical landscape system be considered

gully recharge rates and debris flows a combined numerical modeling and field based investigation haida gwaii british columbia abstract rainfall snowmelt and or other mass movements are possible triggers to initiate debris flows in supply limited landscapes clastic and organic materials together termed debris accumulate in the gully via various geomorphic processes that occur on gully sidewalls the conceptualization of this phenomenon has been termed the gully recharge rate with several recent field studies measuring such rates in coastal british columbia in the present study a simple numerical model is introduced to estimate debris flow volumes in haida gwaii british columbia based on debris flow recurrence intervals gully recharge rates and factors affecting deposition of debris flow material debris flow volumes obtained in model runs are somewhat lower than field based values by about half which is a reasonable result for this exploratory study the annual erosion rate clastic material for debris flows in the model run is 0 031 mm yr 1 this value is about 0 57 of the field based value and is lower than the erosion rate for debris slides in haida gwaii of 0 1 mm yr 1 deposition of debris flows in the model occurs in 60 of cases due to a decrease in channel gradient with deposition resulting from high stream junction angles being less common locations for initiation of debris flow deposition were situated in stream orders 3 and 4 in 60 of cases sensitivity analysis shows that in comparison to other model variables recharge rate has the greatest effect on the statistics and frequency distributions of debris flow volumes and total debris flow volume summation of all debris activity in a basin over the study time period

characteristics of the size distribution of recent and historical landslides in a populated hilly region despitetheavailabilityofstudiesonthefrequencydensityoflandslideareasinmountainousregions frequency areadistributions of historical landslide inventories in populated hilly regions are absent this study revealed that the frequency area distribution derived from a detailed landslide inventory of the flemish ardennes belgium is significantly different from distributions usually obtainedinmountainousareaswherelandslidesaretriggeredbylarge scalenaturalcausalfactorssuchasrainfall earthquakesorrapid snowmelt instead the landslide inventory consists of the superposition of two populations i e i small b1 2 10 2 km 2 shallow complexearthslides that areat most30yrold and ii large n1 2 10 2 km 2 deep seatedlandslides that areolder than100yr both subpopulations are best represented by a negative power law relation with exponents of 0 58 and 2 31 respectively this study focused on the negative power law relation obtained for recent small landslides and contributes to the understanding of frequency distributions of landslide areas by presenting a conceptual model explaining this negative power law relation for small landslides in populatedhilly regions according to the model hilly regions canberelatively stable under the present dayenvironmental conditions andlandslidesaremainlytriggeredbyhumanactivitiesthathaveonlyalocalimpactonslopestability therefore landslidescausedby anthropogenic triggers are limited in size and the number of landslides decreases with landslide area the frequency density of landslide areas for old landslides is similar to those obtained for historical inventories compiled in mountainous areas as apart from the negative power law relation with exponent 2 31 for large landslides a positive power law relation followed by a rollover is observed for smaller landslides however when analysing the old landslides together with the more recent ones the present day higher temporal frequency of small landslides compared to large landslides obscures the positive power law relation and rollover 2007 elsevier b v all rights reserved

impact of the equatorial deep jets on estimates of zonal transports in the atlantic the structure and variability of the zonal equatorial flow in the atlantic is studied on the basis of velocity profiles obtained with lowered acoustic doppler current profilers during multiple surveys the vertical extent of the zonal currents is found to vary considerably it can be as small as 100 m or as large as 1000 m in the atlantic vertical scales of 400 600 m have been associated with the equatorial deep jets they are also frequently called deep jets or stacked jets typical amplitudes of the zonal velocity are about 20 cm s 1 an analysis of quasi synoptic surveys indicates that the zonal extent of most jets is likely to be at least 27d they can rise or deepen from west to east although the deepening was observed more often and is often more pronounced the west to east deepening can be as large as 320 m 10d basin wide mean depth changes of the jets are mostly on the order of 50 m 10d and the largest depth changes are typically observed between 35d and 23d w the existence of these changes indicates that vertically propagating equatorially trapped waves might be one cause for the jet structure however the dependence of the slope on the longitude indicates that other processes must be involved as well the typical vertical extent of the jets is small enough to result in several direction changes of the zonal flow in the antarctic intermediate water aaiw and the north atlantic deep water nadw layer from transport estimates for 14 meridional sections it is found that the transport for the westward component of the flow within the aaiw layer 500 1000 m can be as large as 24 sv 1 sv 10 6 m s 1 within 1d of the equator for the eastward component of the flow in the aaiw layer the transport can be as large as 8 sv adding the transport components for each section results in a range of total aaiw transports from 24 to 7 sv this suggest that the annual mean transport of aaiw is westward the only months with eastward total transports are june and july this is consistent with earlier lagrangian and some other observations that indicated that the aaiw flow along the equator is governed by an annual cycle in the nadw layer 1200 3900 m the transport for the westward eastward flow can be as large as 25 sv 23 sv within 1d of the equator this results in a range of total nadw transports from 10 to 18 sv the variations of the total transports of aaiw and nadw are anti correlated with a correlation coefficient of 0 86 since only eight sections reached deep enough to allow transport estimates in the nadw layer it is more difficult to come to a conclusion about the mean transport in this layer than for the transport in the aaiw layer for the latter layer 14 sections were available nevertheless the obtained estimates suggest that the total nadw transport may be eastward

encounter of a deep western boundary current with the equator a numerical spin up experiment the encounter of a deep western boundary current with the equator is studied using an ultra high resolution numerical model of the equatorial ocean in a study of the origin of the deep equatorial current system the integration was carried out from a state of rest to 3500 days the spin up experiment shows that the deep western boundary current upon encountering the equator first turns along the equator the time scale of spin up is fast along the equator and the boundaries about 250 days but is considerably slower off the equator after this initial response the western boundary current slowly begins to penetrate into the opposite hemisphere as expected from the linear theory the eastward equatorial current gradually slows down the total water mass transport in the equatorial branch decreases steadily until by day 3000 it has dwindled to zero and all the mass transport in the western boundary current crosses into the other hemisphere however a vestige of the equatorial branch remains until the end of the integration with the speed of less than 3 cm s and with intermittent meandering an analysis of the momentum balance indicates that this meander may be a free equatorial inertial oscillation we postulate that a permanent steady bifurcation of the mid depth western boundary current that carries substantial mass does not occur and eventually all of the mass transport will continue into the opposite hemisphere the asymptotic flow field seems incompatible with the tracer field observed in the atlantic which clearly shows a splitting at the equator of the tracer signal associated with the upper north atlantic deep water we speculate that an inherently time dependent explanation of the tracer tongue is called for

quantification of controls on regional rockfall activity and talus deposition kananaskis canadian rockies abstract rockfall is a significant geomorphic process in many mountainous regions that also poses a notable natural hazard risk most previous studies of rockfall erosion have investigated the mechanics and rates of local rockwall retreat and talus deposition with only a few investigations of rockfall and or associated talus considering larger spatial scales i e drainage basin mountain range the purpose of the current research is to investigate the areal extent of rockfall talus and controlling factors of its distribution over regional spatial scales of order 102 km2 in kananaskis canadian rockies to inform our understanding of its significance in mountain development to achieve this goal a large talus inventory is collected and analyzed for 11 steep tributaries of the kananaskis river canadian rockies talus accumulations associated with rockfall provide evidence about the nature and rates of rockfall activity that supplies sediment to these deposits and are the focus of the present study to quantify the controls of rockfall talus activity in this region we analyze the association of talus deposits with structural geology glacial topography and temperature related weathering i e frost cracking a total of 324 talus polygons covering a surface area of 28 51 km2 are delineated within the 11 study basins with the number of talus polygons in each study basin ranging from 1 to 73 analysis of the talus inventory shows that cirques and glacially sculpted valleys are locations of notable talus accumulation in kananaskis with other locations of significant talus deposition being associated with thrust faults we also found that the upper elevations at which talus deposits are typically found are the general range of elevations experiencing a notable number of days in the frost cracking window when this window is defined as 3 to 15 c no such association is found for the frost cracking window of 3 to 8 c estimates of average erosion rates for all study basins combined are between 0 15 mm y 1 lower estimate to 3 1 mm y 1 upper estimate rockfall activity is expected to have been most active for the several millennia following deglaciation during the paraglacial period when hillslopes were oversteepened

the atlantic deep western boundary current water masses and transports near the equator the distributions and transports of deepwater masses at the western boundary in the tropical atlantic off brazil have been studied on three surveys along 35 degrees w and 5 degrees s and one at 10 degrees s transports are obtained from direct measurements of the velocity fields pegasus profiling system and lowered acoustic doppler current profiler and from geostrophic computations using chlorofluoromethane cfm and hydrographic distributions four water masses could be identified forming the north atlantic deep water nadw system two of these have a high cfm content the shallow upper nadw sunadw and the overflow lower nadw olnadw these exhibit the highest velocity signals at 35 degrees w where distinct flow cores seem to exist most of the southeastward flow of the sunadw centered around 1600 m occurs 320 km offshore between 3 degrees 09 s and 1 degrees 50 s 9 7 3 3 sv farther north in that section a highly variable reversing flow is found in a second velocity maximum the transport of olnadw centered around 3800 m of 4 6 2 6 sv is guided by the parnaiba ridge at 1 degrees 45 s 35 degrees w the water masses located between the two cfm maxima the labrador sea water lsw and the lnadw old water mass lnadw old did not show any persistent flow features however a rather constant transport of 11 1 2 6 sv was observed for these two layers the total southeastward flow of the nadw at 35 degrees w showed a transport of 26 8 7 0 sv if one neglects the reversing sunadw north of 1 degrees 50 s at 5 degrees s the flow of all deepwater masses shows vertically aligned cores the main southward transport occurred near the coast 19 5 5 3 sv the boundary current is limited offshore by a flow reversal present in all three surveys but located at different longitudes at 10 degrees s a southward transport of 4 7 sv was observed in november 1992 however the section extended only to 32 degrees 30 w so that probably a significant part of the flow has been missed an important result is the large transport variability between single cruises as well as variability of the spatial distribution of the flow at 35 degrees w which could lead to large uncertainties in the interpretation of single cruise observations despite these uncertainties we suggest a circulation pattern of the various deepwater masses near the equator by combining our mean transport estimates with other observations

relationships among three repeated large scale debris flows at pubugou ravine in the wenchuan earthquake zone the 12 may 2008 wenchuan earthquake in china triggered numerous landslides loose landslide materials can easily evolve into deadly debris flows during wet seasons during the period from 2008 to 2011 three separate large scale debris flows occurred in the pubugou ravine near the epicentre of the earthquake that were among the largest repeated debris flows ever reported approximately 1 76 106 m3 of sediment was deposited during these three events this paper aims to i analyze the movements of solid materials during the repeated debris flows ii discuss the evolution of the initiation mechanisms of these debris flows and iii evaluate the changing depositional morphology of the debris flow fans and examine the particle sizes of the debris flow materials to achieve the above research objectives timely field investigations were undertaken in the past 5 years after each of these debris flow events satellite images were used to delineate the boundaries of the initiation areas the transportation c

stochastic forcing of sediment supply to channel networks from landsliding and debris flow sediment influx to channel networks is stochastically driven by rainstorms and other perturbations which are discrete in time and space and which occur on a landscape with its own spatial variability in topography colluvium properties and state of recovery from previous disturbances the resulting stochastic field of sediment supply interacts with the topology of the channel network and with transport processes to generate spatial and temporal patterns of flux and storage that characterize the sedimentation regime of a drainage basin the regime varies systematically with basin area we describe how the stochastic sediment supply is generated by climatic topographic geotechnical and biotic controls that vary between regions the general principle is illustrated through application to a landscape where sediment is supplied by mass wasting and the forcing variables are deterministic thickening of colluvium random sequences of root destroying wildfires and random sequences of rainstorms that trigger failure in a population of landslide source areas with spatial variance in topography and colluvium strength landslides stop in channels or convert to scouring debris flows depending on the nature of the low order channel network sediment accumulates within these channels for centuries before being transferred downstream by debris flows time series of sediment supply transport and storage vary with basin scale for any combination of climatic topographic and geotechnical controls in a companion paper benda and dunne this issue we use simulations of timing volumes and locations of mass wasting to study the interaction between a stochastically forced sediment supply and systematic changes of storage and flux through channel networks

low frequency variability in the equatorial atlantic abstract low frequency v and u component oscillations in the eastern equatorial atlantic are addressed using lime series of up to 1 5 years duration from the lower portion of the main thermocline a distinct frequency separation is observed with characteristic time scales of 1 month for v and 4 8 months for u the principal v component oscillations correspond to seasonally modulated linear equatorially trapped rossby gravity waves apparently generated at the surface in the central equatorial atlantic by shear instability between the south equatorial current and the north equatorial countercurrent their length and time scales are well defined and they agree with theoretical predictions the principal u component oscillations correspond to the deep zonal jets observed by recent profiling experiments in the indian and pacific oceans the vertical scales found here agree with the results from the other oceans however insufficient data are available anywhere to ascertain zonal scales linear theory would

extended deep equatorial layering as a possible imprint of inertial instability the deep equatorial track of the world ocean is subject to intense zonal flow fields that still remain to be better understood inertial instability has been invoked to explain some of its features here we present possible in situ imprints of such a mechanism in the equatorial atlantic ocean below the thermocline we analyse the observed pattern of homogeneous density layers of 50 100 m vertical scale which are characterized by a large meridional coherency up to 2degrees of latitude a concentration in the vicinity of the equator and foremost a vertical localization within regions of well mixed angular momentum westward jets these distinctive properties suggest inertial instability to be a plausible mechanism for this extended layering numerical simulations forced by a time oscillating shear reproduce the observed density layering characteristics the prescription of deep jets in the background flow controls the vertical localization of the layering inside westward jets

catastrophic debris flows on 13 august 2010 in the qingping area southwestern china the combined effects of a strong earthquake and subsequent rainstorms in the wenchuan area in sw china an abundance of loose co seismic landslide debris was present on the slopes after the wenchuan earthquake which in later years served as source material for rainfall induced debris flows or shallow landslides slopes composed of cambrian sandstones and siltstones intercalated with slates appeared to be most susceptible to co seismic landsliding a total of 20 debris flows are described in this paper all were triggered by heavy rainfall on 13th of august 2010 field reconnaissance and measurements supported by aerial photo interpretation were conducted to identify the locations and morphological characteristics of the debris flow gullies in order to obtain information about surface area and volume of landslides and the debris flows the debris flows in the study area were initiated by two processes a run off erosion on co seismic landslide material and concentrated erosion of landslide debris in steep channels b new landslides that transform into debris flows the volume of debris flow deposits on individual fans varies by many orders of magnitude the smallest deposit has a volume of from 5760 to 3 1 million m3 a comparison of the measured volumes deposited on the fan with the volumes of debris stored in the catchment shows the huge potential for future debris flow activity whilst there is a weakly significant positive correlation between these two volumes no significant statistical correlation could be established between volumes of debris flow deposits and other morphometric parameters of the catchment a catastrophic debris flow catchment the wenjia catchment was selected as an extreme case to show in detail the mechanism of debris flow formation as a result of intensive erosion in loose material which was deposited by a rock avalanche during the 2008 earthquake event analyses of the meteorological conditions that triggered these debris flows show one day antecedent precipitation varying between 67 7 and 137 6 mm with a mean rainfall intensity of about 7 3 to 22 5 mm h a rainfall event with peak intensity of 38 7 mm h triggered the largest debris flow event rainfall data related to five debris flow events in the wenjia torrent was used to establish a primary rainfall intensity duration relationship for the triggering of debris flows which was compared to other rainfall duration thresholds from other parts of the world in the discussion emphasis is laid on the need to unravel the process mechanisms which initiated the debris flows for a better understanding and assessment of meteorological thresholds

temporal and spatial structure of the equatorial deep jets in the pacific ocean abstract the spatial and temporal structure of the equatorial deep jets edjs in the pacific ocean is investigated using ctd station data taken on the equator from 1979 through 2001 the edjs are revealed in profiles of vertical strain z estimated from the ctd data in a stretched vertical coordinate system the majority of synoptic meridional sections were occupied over an 8 yr span west of the date line two decade equatorial time series are available at both 110 w and 140 w analysis shows the expected equatorial trapping of z but yields little new detailed information about the edj meridional structure analysis of the equatorial data yields novel results the edjs are most easily seen in the eastern pacific at and east of 140 w there they may be isolated from the influence of higher frequency rossby waves generated by surface forcing spectral analysis of equatorial z profiles shows a significant and coherent peak at 400 sdbar vertical wavelength with no 1 56 10 3 s 1 from 95 w to 142

results from a velocity transect along the equator from 125 to 159 w abstract during march april 1980 a velocity and ctd transect was made in the pacific along the equator from 110 to 180 w the horizontal baroclinic pressure gradient was observed to be primary confined between 160 and 130 w direct velocity profiles between 125 and 159 w showed the equatorial undercurrent to be a continuous feature maximum eastward transport per unit width in the undercurrent was 2 5 108 cm2 s 1 at 150 w and decreased both westward and eastward to about 1 5 108 cm2 s 1 at 159 w and at 125 w despite these variations the maximum speeds along the transect remained 150 cm s 1 beneath the undercurrent the velocities decreased and were of the order of 25 cm s 1 they exhibited small scale variation in the vertical as has recently been observed at other equatorial locations above 1600 m the vertical wavelength of these variations in the zonal component was 300 m small scale features in these zonal velocities were identifiable over 10 of longitude 1000 km the small vertical an

the impacts of logging on landslide activity at clayoquot sound british columbia abstract the objective of this study was to investigate the impacts of logging on landslide activity in clayoquot sound on the west coast of vancouver island british columbia a total of 1004 landslides were documented in order to test the hypothesis that areas affected by logging activities show different density frequency and magnitude characteristics of landsliding than areas unaffected by logging the frequency of landslides in logged terrain was found to be nine times higher than in undisturbed forest an exponential increase in landslide frequency within the area logged was observed on a large watershed scale failures in logged terrain occur on gentler slopes than in natural terrain partly because fewer slopes steeper than 40 have been logged debris slides and debris flows are the most frequently occurring mass movements initiating mostly from road fill failures and from within cutblocks most landslides initiated on se facing slopes with the highest landslide frequency near the coast and diminishing exponentially further inland this pattern of activity most likely reflects the greater impact of severe storms arriving from the pacific with winds dominating from the southeast concave and straight slopes are most susceptible to landslide initiation a preliminary examination of geologic control on the frequency of landslides suggests that the quatsino formation the island plutonic suite and the sicker group are significantly above the average rate further work is needed to identify and quantify factors confounding the trends and correlations identified in this overview study results obtained in this study will be used to implement changes in forest management

atlantic equatorial deep jets space time structure and cross equatorial fluxes the so called equatorial stacked jets are analyzed with ship board observations and moored time series from the atlantic ocean the features are identified and isolated by comparing vertical wavenumber spectra at the equator with those a few degrees from the equator mode filtering gives clear views of the jets in meridional sections the typical extent being 618 in latitude the vertical structure can be well described explaining 82 of the variance by n21 stretched cosines with a gaussian amplitude tapering in the vertical the stretched wavelengths are somewhat variable fitting jets of a fixed stretched wavelength to four moored sensors in the depth range 1300 1900 m allows one to track the vertical phase of the jets with an rms error of 308 458 the resulting fit from a 20 month moored time series shows long periods of unchanging jet conditions and intermittent times of high variability there is no significant vertical propagation on these timescales nor a seasonal reversal using a composite from many different experiments interannual variability is visible however a possible mechanism for the stacked jets is inertial instability resulting from background meridional shears at the equator a condition is that the ertel potential vorticity becomes zero somewhere due to meridional asymmetries in the zonal flows the ship board observations show that this may be approximately fulfilled by the instantaneous zonal low mode flows at various depths resulting from an excess of zonal momentum south of the equator most of the time inertial instability should act to redistribute this zonal momentum and our mooring data show indeed persistent northward momentum flux but not at the depth levels expected the momentum transport might suggest that the jets can also flux or mix other properties across the equator

the deep currents in the eastern equatorial atlantic ocean 1 in the atlantic ocean equatorial deep jets have been observed in the central and western equatorial basin here we present three meridional velocity sections carried out in boreal summer 2000 in the eastern equatorial atlantic at that time the deep equatorial jets were observed to weaken or to vanish in the gulf of guinea toward the african coast at 10 w the comparison with currents measured one year before in boreal summer 1999 along with tracer distributions confirm the existence of an eastward route along the equator of part of the north atlantic deep water

colluvial sediment dynamics in mountain drainage basins abstract colluvial sediment dynamics are examined using a 70 year landslide inventory in formerly glaciated mountain drainage basins of coastal british columbia canada landslide sediment transfer is documented by identifying landslide types and by characterizing preferential sites of landslide initiation delivery and storage across spatial scales data analysis reveals that open slope landslides delivering material to seasonal or perennial channels and fluvial terraces are the dominant mechanisms of sediment transfer this finding suggests high instability of the low order channel network and its ongoing re organization degradation after generalized sediment recharge occurred in the last glacial maximum in the study period landslide activity across the landscape has generated net degradation on planar slopes and first order colluvial channels whereas unchannelled valleys higher order colluvial channels and alluvial channels have accumulated material the scaling relation of the landslide sediment yield appears to be controlled by the spatial arrangement of the relict glacial macro forms landslide yield is highest in unchannelled topography decreases at the scale of channel initiation ad 0 002 km2 and remains constant for drainage areas where length scales of cirque valley walls and hanging valley floors overlap 0 002

contemporary movements and tectonics on canada s west coast a discussion abstract evidence from published tidal records and geodetic relevelling data in british columbia indicates that there is a consistent pattern of contemporary uplift on the outer coast 2 mm yr and subsidence on the inner coast 1 2 mm yr the zero uplift contour or hinge line runs through hecate strait georgia strait and victoria this pattern continues southwards into washington state but is interrupted to the north by considerable uplift in southeastern alaska although glacio isostatic recovery has dominated vertical movements in the region over the last 10 000 years the distribution and trend of the observed contemporary movements are not compatible with the pattern to be expected from this source and are most probably tectonic in origin there is however no clear distinction between the movements seen opposite the queen charlotte transform margin and the vancouver island convergent margin comparison with movements observed at other active plate margins show that the pattern is essentially similar to that seen in association with subduction and convergence the paradox that the vertical movement rates are much too great to explain observed geology and topography may be soluble by assuming that discontinuous lateral shifts of the movement pattern occur on a scale of hundreds of thousands of years

work persistence and formative events the geomorphic impact of landslides abstract understanding the scale and frequency of physical processes that act upon and form the surface of the earth is a fundamental goal of earth science here we determine the magnitudes of landslides that impact the landscape in terms of work persistence and formative events a systematic analysis of rapid landsliding the analysis did not consider creep and other slow semi continuous processes indicates that moderate sized landslides do the most work transporting material on hillslopes the work peak defines the moderate magnitude and that magnitude varies based on local physiography and climate landslides that form the work peak are distinct from catastrophic landslides that are themselves formative and system resetting the persistence time for debris slides debris flows p ds and rock slides rock avalanches p rs is calculated over six orders of magnitude we consider an event catastrophic when it persists in the landscape as described by a persistence ratio p f an order of magnitude longer than the population of landslides that form the work peak

effects of large deep seated landslides on hillslope morphology western southern alps new zealand 1 morphometric analysis and air photo interpretation highlight geomorphic imprints of large landslides i e affecting 1 km2 on hillslopes in the western southern alps wsa new zealand large landslides attain kilometer scale runout affect 50 of total basin relief and in 70 are slope clearing and thus relief limiting landslide terrain shows lower mean local relief relief variability slope angles steepness and concavity than surrounding terrain measuring mean slope angle smoothes out local landslide morphology masking any relationship between large landslides and possible threshold hillslopes large failures also occurred on low gradient slopes indicating persistent low frequency high magnitude hillslope adjustment independent of fluvial bedrock incision at the basin and hillslope scale slope area plots partly constrain the effects of landslides on geomorphic process regimes landslide imprints gradually blend with relief characteristics at orogen scale 102 km while being sensitive to length scales of slope failure topography sampling and digital elevation model resolution this limits means of automated detection and underlines the importance of local morphologic contrasts for detecting large landslides in the wsa landslide controls on low order drainage include divide lowering and shifting formation of headwater basins and hanging valleys and stream piracy volumes typically mobilized yet still stored in numerous deposits despite high denudation rates are 107 m3 and theoretically equal to 102 years of basin wide debris production from historic shallow landslides lack of absolute ages precludes further estimates deposit size and mature forest cover indicate residence times of 101 104 years on these timescales large landslides require further attention in landscape evolution models of tectonically active orogens

variability of the horizontal velocity structure in the upper 1600 m of the water column on the equator at 10 w this paper presents initial results from new velocity observations in the eastern part of the equatorial atlantic ocean from a moored current meter array during the equalant program 1999 2000 a mooring array was deployed around the equator near 10 w that recorded one year of measurements at various depths horizontal velocities were obtained in the upper 60 m from an upward looking acoustic doppler current profiler adcp and at 13 deeper levels from current meters between 745 and 1525 m to analyze the quasiperiodic variability observed in these records a wavelet based technique was used quasiperiodic oscillations having periods between 5 and 100 days were separated into four bands 5 10 10 20 20 40 and 40 100 days the variability shows i a strong seasonality the first half of the series is dominated by larger periods than the second one and ii a strong dependence with depth some oscillations are present in the entire water column while others are only present at certain depths for the oscillations that are present in the entire water column the origin of the forcing can be traced to the surface while for the others the question of their origin remains open phase shifts at different depths generate vertical shears in the horizontal velocity component with relatively short vertical scales this is especially visible in long duration events 100 days of the zonal velocity component comparison with a simultaneous lowered acoustic doppler current profiler ladcp section suggests that some of these flows may be identified with equatorial deep jets a striking feature is a strong vertical shear lasting about 7 months between 745 and 1000 m these deep current meter observations would then imply a few months of duration for the jets in this region

sediment flux from a mountain belt derived by landslide mapping in humid uplands landsliding is the dominant mass wasting process in the western southern alps of new zealand landslides are scale invariant and have a power law magnitude frequency distribution independent studies from other regions suggest that this is a general property of landsliding this observation is of critical importance to the evaluation of the impact of events of different length scales over different time intervals on landscape evolution it is particularly useful when estimating regional geomorphic rates because it constrains the frequency and overall significance of extreme events which cannot otherwise be evaluated by integrating the complete response of the system we estimate the regional denudation rate due to landsliding to be 9 4 mm yr 1 sediment discharge from the western southern alps is dominated by landslide derived material

evaluating debris slide occurrence using digital data paraglacial activity in chilliwack valley british columbia debris sliding is one of the most important processes acting to transport sediment within mountainous regions detailed study of debris slide activity at the basin scale typically involves landslide inventories generated from aerial photographs however it has been shown that some types of rapid mass movement can be accurately identified using a combination of high resolution satellite imagery and digital elevation data this approach is beneficial as the digital products allow for a more accurate and efficient data throughput into various types of geomorphic analysis here we demonstrate the use of an automated inventory in the geomorphometric evaluation of debris slide initiation for the chilliwack basin british columbia canada our results indicate that the occurrence of debris sliding is primarily determined by topographical controls for basins that are in equilibrium with the existing climate the frequency of debris sliding should demonstrate a strong relationship to bedrock geology as the production of unconsolidated materials available for failure is a function of weathering rates under these conditions the lack of bedrock control within the chilliwack basin suggests a state of paraglacial relaxation wherein glacial deposits dominate the sediment cascade within the area therefore topographic parameters can be used to discriminate the location of metastable slopes where debris slide erosion will be active the use of digital data in the characterization of debris slide occurrence would seem to be a viable alternative to the more traditional methods

ventilation of the equatorial atlantic by the equatorial deep jets equatorial deep jets edjs are a prominent flow feature of the equatorial atlantic below the equatorial undercurrent down to about 3000 m here we analyze long term moored velocity and oxygen observations as well as shipboard hydrographic and current sections acquired along 23 degree sign w and covering the depth range of the oxygen minimum zones of the eastern tropical north and south atlantic the moored zonal velocity data show high baroclinic mode edj oscillations at a period of about 4 5 years equatorial oxygen observations which do not resolve or cover a full 4 5 yr edj cycle nevertheless reveal large variability with oxygen concentrations locally spanning a range of more than 60 mol kg 1 we study the effect of edjs on the equatorial oxygen concentration by forcing an advection diffusion model with the velocity field of the gravest equatorial basin mode corresponding to the observed edj cycle the advection diffusion model includes an oxygen source at the western boundary and oxygen consumption elsewhere the model produces a 4 5 yr cycle of the oxygen concentration and a temporal phase difference between oxygen concentration and eastward velocity that is less than quadrature implying a net eastward oxygen flux the comparison of available observations and basin mode simulations indicates that a substantial part of the observed oxygen variability at the equator can be explained by edj oscillations the respective role of mean advection edjs and other possible processes in shaping the mean oxygen distribution of the equatorial atlantic at intermediate depth is discussed key points equatorial deep jets strongly affect oxygen distribution variability mean oxygen ditribution in the equatorial atlantic at intermediate depth gravest equatorial basin mode forces an advection diffusion model

deep jets in the equatorial atlantic ocean deep velocity profiles taken in the equatorial atlantic ocean show equatorially trapped deep jets with similar features to those of the indian and pacific oceans a zonal velocity of the order of 10 to 20 cm s 1 and a meridional scale of 1 in the pacific and indian oceans the zonal extent of the jets is at least 15 of longitude owing to the lack of synoptic measurements we have no information on the zonal scale in the atlantic ocean but we present here zonal velocity profiles made at a 16 month interval that have identical baroclinic structure in the western 35 w and central basin 13 w the atlantic jets have a vertical scale larger 400 600 m than those observed in the pacific ocean 250 400 m our measurements confirm the opposite directions of the jets for different seasons in the atlantic ocean furthermore for a given season the vertical profiles of zonal velocity at 35 w 0 are astonishingly similar at a 5 year interval as in the pacific and indian oceans the jets are embedded in a large vertical scale current that changes direction with time the few profiles available in the equatorial atlantic ocean suggest a seasonal reversal of the jets but neither this nor the temporal variability of the large scale current has been adequately resolved

forcing of the atlantic equatorial deep jets derived from observations the equatorial deep jets edjs are an ubiquitous feature of the equatorial oceans in the atlantic ocean they are the dominant mode of interannual variability of the zonal flow at intermediate depth on the basis of more than 10 years of moored observations of zonal velocity at 23 w the vertically propagating edjs are best described as superimposed oscillations of the 13th to the 23th baroclinic modes with a dominant oscillation period for all modes of 1650 days this period is close to the resonance period of the respective gravest equatorial basin mode for the dominant vertical modes 16 and 17 it is argued that since the equatorial basin mode is composed of linear equatorial waves a linear reduced gravity model can be employed for each baroclinic mode driven by spatially homogeneous zonal forcing oscillating with the edj period the fit of the model solutions to observations at 23 w yields a basin wide reconstruction of the edjs and the associated vertical structure of their forcing from the resulting vertical profile of mean power input and vertical energy flux on the equator it follows that the edjs are locally maintained over a considerable depth range from 500 2500 m with the maximum power input and vertical energy flux at 1300 m the strong dissipation closely ties the apparent vertical propagation of energy to the vertical distribution of power input and together with the edjs prevailing downward phase propagation require the phase of the forcing of the edjs to propagate downward

variability at intermediate depths at the equator in the atlantic ocean in 2000 06 annual cycle equatorial deep jets and intraseasonal meridional velocity fluctuations time series of high vertical resolution current meter measurements between 600 m and 1800 m depths on the equator in the atlantic were obtained at two locations 10 and 23 w the measurements have a time span of almost 7 years 2000 06 and provide insights into the temporal scales and vertical structure of variability at intermediate depths variability in the zonal velocity component records is dominated by semiannual annual and interannual fluctuations at semiannual and annual periodicities vertical scales are large on the order of 2000 stretched meters sm and show upward phase propagation in contrast interannual variability is associated with small vertical scale flows called equatorial deep jets edjs presenting downward phase propagation most of the time fitting a plane wave to these small vertical scale flows leads to velocity amplitude vertical scale and temporal scale estimates of 8 normalized cm s 1 440 sm and 4 4 yr however this plane wave cannot explain all the variability presenting small vertical scales indeed the data suggest that along with a seasonal cycle of much larger vertical scale different features with edj vertical scale coexist with the possibility of a semipermanent eastward jet at around 1500 sm variability in the meridional velocity component is dominated by intraseasonal fluctuations in addition at 23 w the meridional component shows low frequency flows that may be due to the interaction of zonal fluctuations with the mid atlantic ridge

modelling hillslope evolution linear and nonlinear transport relations many recent models of landscape evolution have used a diffusion relation to simulate hillslope transport in this study a linear diffusion equation for slow quasi continuous mass movement e g creep which is based on a large data compilation is adopted in the hillslope model transport relations for rapid episodic mass movements are based on an extensive data set covering a 40 yr period from the queen charlotte islands british columbia a hyperbolic tangent relation in which transport increases nonlinearly with gradient above some threshold gradient provided the best fit to the data model runs were undertaken for typical hillslope profiles found in small drainage basins in the queen charlotte islands results based on linear diffusivity values defined in the present study are compared to results based on diffusivities used in earlier studies linear diffusivities adopted in several earlier studies generally did not provide adequate approximations of hillslope evolution the nonlinear transport relation was tested and found to provide acceptable simulations of hillslope evolution weathering is introduced into the final set of model runs the incorporation of weathering into the model decreases the rate of hillslope change when theoretical rates of sediment transport exceed sediment supply the incorporation of weathering into the model is essential to ensuring that transport rates at high gradients obtained in the model reasonably replicate conditions observed in real landscapes an outline of landscape progression is proposed based on model results hillslope change initially occurs at a rapid rate following events that result in oversteepened gradients e g tectonic forcing glaciation fluvial undercutting steep gradients are eventually eliminated and hillslope transport is reduced significantly

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

landslide volumes and landslide mobilization rates in umbria central italy abstract a catalogue of 677 landslides of the slide type was selected from a global database of geometrical measurements of individual landslides including landslide area al and volume vl the measurements were used to establish an empirical relationship to link al in m2 to vl in m3 the relationship takes the form of a power law with a scaling exponent 1 450 covers eight orders of magnitude of al and twelve orders of magnitude of vl and is in general agreement with existing relationships published in the literature the reduced scatter of the experiential data around the dependency line and the fact that the considered landslides occurred in multiple physiographic and climatic environments and were caused by different triggers indicate that the relationship between vl and al is largely independent of the physiographical setting the new relationship was used to determine the volume of individual landslides of the slide type in the collazzone area central italy a 78 9 km2 area for which a multi temporal landslide inventory covering the 69 year period from 1937 to 2005 is available in the observation period the total volume of landslide material was vlt 4 78 107 m3 corresponding to an average rate of landslide mobilization l 8 8 mm yr 1 exploiting the temporal information in the landslide inventory the volume of material produced during different periods by new and reactivated landslides was singled out the wet period from 1937 to 1941 was recognized as an episode of accelerated landslide production during this 5 year period approximately 45 of the total landslide material inventoried in the collazzone area was produced corresponding to an average rate of landslide mobilization l 54 mm yr 1 six times higher than the long term rate the volume of landslide material in an event or period was used as a proxy for the magnitude of the event or period defined as the logarithm base 10 of the total landslide volume produced during the event or period with this respect the new relationship to link al and vl is a starting point for the adoption of a quantitative process based landslide magnitude scale for landslide events

float trajectories in the deep western boundary current and deep equatorial jets of the tropical atlantic abstract fourteen neutrally buoyant sofar floats at a nominal depth of 1800 m were tracked acoustically for 3 7 yr in the vicinity of the western boundary and the equator of the atlantic ocean the trajectories revealed a swift narrow southward flowing deep western boundary current dwbc extending from 7n across the equator two floats crossed the equator in the dwbc and went to 10s two other floats left the dwbc and drifted eastward in the equatorial band 3s 3n three floats entered the dwbc from the equatorial current system and drifted southward these results suggest that at times the dwbc flows directly southward across the equator with a mean velocity of 8 9 cm s averaged over long distances 2800 km at other times dwbc water is diverted eastward near the equator for long periods 2 3 yr which can reduce the mean along boundary velocity to 1 2 cm s this is much less than the instantaneous along boundary velocities in the dwbc which are often above 25 cm s and occasionally exceed 50 cm s mean eastward flowing jets were observed near 2n and 2s bounding a mean westward jet centered on the equator 1s 1n the southern jet at 2s coincides with a cfc rich plume centered south of the equator the cfc plume is inferred to have been advected by the southern jet across the atlantic and into the gulf of guinea

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

stacked jets in the deep equatorial atlantic ocean 1 middepth current measurements in the equatorial atlantic are characterized by elevated levels of energy contained in zonal flows of high baroclinic mode number these alternating zonal flows often called equatorial stacked jets have amplitudes up to 20 cm s 1 and vertical wavelengths of 600 m the jets are most pronounced in the depth range between 500 and 2500 m repeated direct velocity observations at 35 w indicate that the jets are coherent within 1 of the equator individual jets can persist for 1 2 years but they appear and decay rather irregularly the equatorial stacked jets are also found in realistic general circulation model simulations the features grow in amplitude with increasing horizontal and vertical model resolution however even at very high model resolutions their amplitudes are still underestimated in all model simulations high levels of energy related to the stacked jets are found in the vicinity of the western boundary currents wbcs depth range and strength of the wbcs in different experiments are related to depth range and strength of the jets in the interior stacked jets are characterized by eastward wave propagation suggesting that high baroclinic mode kelvin waves radiate energy generated in the wbc into the interior and form the stacked jets

uplifted marine terraces along the alpine fault new zealand three types of evidence indicate that marine terraces are widespread in the southern alps of new zealand i remnants of shore platforms occur as distinct levels of notched ridge crests and flat summits degraded sea cliffs are common ii scattered quartz beach pebbles occur on 16 of 18 levels of exhumed shore platforms in the fox franz josef type area to altitudes as high as 1700 meters iii altitudinal spacings of new zealand terrace flights allow correlation with 18 dated global marine terraces at new guinea which were formed during glacio eustatic highstands of sea level within the last 336 x 10 3 years inferred uplift rates at fox franz josef increased from 3 2 to 7 8 meters per 10 3 years since about 135 x 10 3 to 140 x 10 3 years ago presumably because of increased convergence between the pacific and australian plates

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

reconnaissance sediment budgets for lynn valley british columbia holocene and contemporary time scales volumes of erosional and depositional landforms were estimated by reconnaissance methods in a steep forested drainage basin in the coast mountains british columbia to examine what insight might be gained into the sediment budget in the absence of direct measurements of sediment transfer processes sediment transfers in postglacial and contemporary time were inferred on hillslopes from hillslopes to stream channels and within stream channels data were collected by aerial photographic analysis and field observation postglacial sediment sources are major gullies created by debris slides and flows failures in glaciolacustrine terraces and stream channel degradation depositional landforms consist of talus slopes and colluvial and alluvial fans contemporary sediment sources include debris slides and flows in established gullies and minor processes on hillslopes debris slide and debris flow volumes were calculated and other processes were estimated from regional values erosion rate averaged over postglacial time is 276 t km 2 a 1 0 15 mm a 1 surface lowering with gullies and stream channel degradation contributing 170 and 82 t km 2 a 1 respectively a terminal alluvial fan provides an independent check of the results in contemporary time erosion rates are calculated to be 350 t km 2 a 1 with debris flows and slides contributing nearly all of this sediment the contemporary rate is probably perturbed by recent land use history mass movement processes appear to be the dominant mechanism of sediment transfer and contributions from pleistocene valley deposits have declined significantly during holocene time resume les volumes de terrain erodes et deposes ont ete estimes par des methodes de reconnaissance dans un bassin de drainage boise a pentes abruptes des montagnes cotieres de la colombie britannique afin d etudier quelles connaissances sur le budget sedimentaire pourraient etre acquises en l absence de mesures directes du processus de transfert de sediments les transferts de sediments a l epoque post glaciaire et contemporaine ont ete inferes sur les flancs des cotes des flancs des cotes vers les chenaux des rivieres et dans les chenaux des rivieres les donnees proviennent de l analyse de photographies aeriennes et d observations sur le terrain les sources de sediments post glaciaires sont des ravines creees par des glissements et des coulees de debris des effondrements de terrasses glacio lacustres et la degradation de chenaux les formes de terrain creees par deposition comprennent des tabliers d eboulis et des deltas colluviaux et alluvionnaires les sources contemporaines de sediments comprennent des glissements et des coulees de debris dans des ravines etablies et des processus mineurs sur des pentes les volumes des glissements et des coulees de debris ont ete calcules et d autres processus ont ete evalues a partir de valeurs regionales la moyenne du taux d erosion pour la periode post glaciaire est de 276 tonnes km 2 a 1 abaissement de la surface de 0 15 mm a les ravines et la degradation des chenaux des ruisseaux contribuant respectivement 170 et 82 tonnes km 2 a 1 un delta alluvionnaire terminal permet une verification independante des resultats a l epoque contemporaine les taux d erosion sont calcules comme etant 350 tonnes km 2 a 1 et les glissements et des coulees de debris y contribueraient pour la presque totalite le taux contemporain est probablement perturbe par l utilisation recente du terrain les processus de mouvements de masse semblent etre le mecanisme dominant de transfert de sediments et les contributions provenant des depositions dans les vallees au pleistocene ont diminue de facon significative durant l holocene traduit par la redaction campbell and church 713

deep circulation in the equatorial atlantic ocean in the atlantic ocean the northward export of warm surface water is compensated by a southward flow of cold north atlantic deep water nadw the nadvv is transported southward along the american continental margin within the deep western boundary current dwbc some tracer and float observations have shown that part of the dwbc water flows eastward along the equator here we present three meridional velocity sections which give an instantaneous image of the lop to bottom zonal circulation along the equatorial atlantic they reveal the presence of equatorial deep jets edjs between 1 30 n and 1 30 s alternating eastward westward currents with short vertical scale surrounded by columns of eastward currents the extra equatorial jets or eejs at 2 n and 2 s in addition to direct velocity measurements tracer distributions give indications of water mass feeding of the edjs and eejs by the dwbc

zonal intermediate currents in the equatorial atlantic ocean acoustic float data collected near 800 m depth are used to map zonal mean currents within the antarctic intermediate water aaiw tongue in the equatorial atlantic alternating zonal jets of 2 latitudinal width are revealed between 6 s and 6 n displacements from profiling floats drifting near 1000 m depth also reveal similar zonal jets at the base of the aaiw layer the strongest jets 15 cm s 1 peak are found at 4 s 2 s 0 2 n and 4 n they are coherent longitudinally over order of 3000 km and poleward of 1 s and 1 n generally coherent vertically between 800 m and 1000 m large seasonal fluctuations exist at both levels within 1 of equator aaiw at 800 m flows westward 8 cm s 1 mean in boreal summer and fall but eastward 3 cm s 1 mean in winter whereas the flow at 1000 m is eastward in late fall and winter

the role of landslides in mountain range evolution abstract we review the role of landslides in current concepts of the topographic development of mountain ranges we find that many studies in this field address basin or orogen scale competition between rock uplift and fluvial bedrock erosion hillslopes in general and bedrock landslides in particular are often assumed to respond rapidly to incision and development of the fluvial drainage network this leads to a one sided view of the geomorphic coupling between hillslopes and rivers that emphasizes the fluvial control of hillslopes but ignores the alternative view that landslides can affect the fluvial network there is growing evidence that landslides are a dominant source of sediment in mountain belts and that they exert a direct geomorphic control on fluvial processes landslides can influence the river network in a variety of ways from determining basin area and drainage divide positions to setting streamwise variations in sediment load and calibre the geomorphic legacy of large landslides on hillslope and channel morphologies may persist for up to 104 yr adding considerable variability to fluvial erosion and sedimentation patterns over these timescales we identify a number of questions for future research and conclude that a better understanding and quantification of the geomorphic feedbacks between landslides and river channels builds an important link between short term 105 yr landscape evolution models

evaluating volume of coseismic landslide clusters by flow direction based partitioning abstract a strong earthquake can trigger thousands of co seismic landslides the evaluation of the volume of such co seismic landslides is essential for landslide risk assessment and long term post earthquake hazard evaluation empirical volume area power laws are often applied to estimate the landslide volume when several small landslide deposits form a large cluster on the hillslope blurry boundaries of the clustered co seismic landslides may lead to seemingly one large landslide and grossly overestimated landslide volume in this paper we propose a flow direction based method to identify the boundaries of a cluster of landslides and to partition co seismic landslides three watersheds that were severely impacted by co seismic landslides in the wenchuan earthquake region are chosen for case studies each co seismic landslide cluster in these watersheds was interpreted from images taken shortly after the earthquake and partitioned into individual landslides in accordance with a flow direction map that is processed based on a local digital terrain model finally the volume of each individual landslide is calculated using an empirical volume area power law the adopted power law scaling relationship is selected from six widely used empirical relations and verified by 11 local landslide cases the proposed flow direction based partitioning method is further verified by clear boundaries of landslides that were exposed after storms as well as supplementary field survey results the proposed method results in similar landslide boundaries and volumes as the field survey results the uncertainty of this approach is below 19 if no partitioning is conducted the total volume of the landslide cluster can approach twice that from the field investigations

tracer distributions and deep circulation in the western tropical atlantic during cither 1 and etambot cruises 1993 1996 this paper presents cfc and nontransient tracer observations in the western equatorial atlantic ocean on repeated sections along 7 30 n the 35 w meridian and a transect crossing the ceara rise three world ocean circulation experiment cruises have been carried out in this area in february march 1993 cither 1 and september october 1995 and april may 1996 etambot 1 and 2 together with the tracer data the direct current measurements are used to deduce the circulation pathways the data confirm the principal circulation features of the upper north atlantic deep water within the area the deep western boundary current flows southward along the continental slope while adjacent to the dwbc there is a northward flow corresponding to the dwbc recirculation whose origin appears variable the largest variability is observed along the 35 w meridional section where the dwbc bifurcates eastward north of 3 s but the eastward equatorial flow does not appear to be permanent at the middle north atlantic deep water level cfc distributions exhibit the most important contrast between waters of northern and southern origin the circulation at the lower north atlantic deep water level mainly controlled by the topography looks more permanent because the dwbc is regularly observed during the three cruises and there is no evidence for a northwestward recirculation along the mid atlantic ridge the transient behavior of cfc distributions which is superimposed on local circulation effects can be seen clearly through their temporal evolution within the dwbc the variability of the deep circulation observed during the 1993 1996 interval rules out a dominant variability in response to semi annual forcing

magnitude and frequency of rock falls and rock slides along the main transportation corridors of southwestern british columbia the two main transportation corridors of southwestern british columbia are subject to a range of rock slope movements rock falls rock slides and rock avalanches that pose significant risks to r

high resolution fingerprints of past landsliding and spatially explicit probabilistic assessment of future reactivations aiguettes landslide southeastern french alps the purpose of this study was to reconstruct spatio temporal patterns of past landslide reactivation and the possible occurrence of future events in a forested area of the barcelonnette basin southeastern french alps analysis of past events on the aiguettes landslide was based on growth ring series from 223 heavily affected mountain pine pinus uncinata mill ex mirb trees growing on the landslide body a total of 355 growth disturbances were identified in the samples indicating 14 reactivation phases of the landslide body since ad 1898 accuracy of the spatio temporal reconstruction is confirmed by historical records and aerial photographs logistic regressions using monthly rainfall data from the histalp database indicated that landslide reactivations occurred due to above average precipitation anomalies in winter they point to the important role of snow in the triggering of reactivations at the aiguettes landslide body in a subsequent step spatially explicit probabilities of landslide reactivation were computed based on the extensive dendrogeomorphic dataset using a poisson distribution model for an event to occur in 5 20 50 and 100 yr high resolution maps indicate highest probabilities of reactivation in the lower part of the landslide body and increase from 0 28 for a 5 yr period to 0 99 for a 100 yr period in the upper part of the landslide body probabilities do not exceed 0 57 for a 100 yr period and somehow confirm the more stable character of this segment of the aiguettes landslide the approach presented in this paper is considered a valuable tool for land use planners and emergency cells in charge of forecasting future events and in protecting people and their assets from the negative effects of landslides

modeling cliff erosion using negative power law scaling of rockfalls we model cliff erosion using an approach based upon the negative power law scaling properties of rockfall magnitude frequency distributions these are derived from an extensive high resolution rockfall inventory for a series of sea cliffs near staithes north yorkshire a comparison between observed volumetric erosion and that produced by the model yields a statistically significant correlation however we note that the temporal resolution of the inventory can have an influence on results our data indicate that monthly inventories are capable of producing magnitude frequency relations that model erosion in good correlation with observed events however for months that experience high magnitude events seasonal inventories are more appropriate furthermore increasing the return period between surveys has the effect of increasing the superimposition of rockfall events thereby reducing the slope of the power law giving an incorrect picture of the scaling properties of rockfalls at this site applying observed variations in the negative power law scaling parameters to a probabilistic simulation model of cliff retreat provides a new means of assessing the most likely erosional scenarios and indicates that the current dataset may not be indicative of long term cliff evolution this may provide a quantitative means of establishing an appropriate time window for characterizing rockfall erosion over decadal time scales