can the waves generated by fast ferries be a physical model of tsunami the potential of long ship induced waves to serve as a physical model for tsunami waves called simply tsunami below is examined such waves wavelengths more than 200 m at depths down to 10 20 m are induced by high speed ferries sailing at near critical speeds in semisheltered relatively shallow areas it is shown based on experience from tallinn bay baltic sea that for many aspects these waves can model nearshore dynamics and runup of tsunami caused by landslides including processes of wave refraction diffraction and sea bottom interaction in bays and harbors many governing nondimensional parameters such as the nonlinearity dispersion reynolds and ursell numbers surf similarity parameter breaking parameter etc of the largest ship waves and landslide tsunamis have the same order of magnitude it is especially important that use of ship waves for wave propagation and runup studies allows their spatial structure to be accounted for adequately near critical ship waves can therefore be used as a natural substitute for tsunami for study under controlled and safe conditions

tsunami in coastal zone due to meteorite impact the impact of a meteorite into the ocean surface is a rare phenomenon however it can be catastrophic especially for the coastal area the aim of the paper is to describe the evolution of the tsunami impulse due to meteorite impact in shallow water including energy dissipation due to bottom friction and wave breaking as the exact nonlinear solutions for tsunami transformation with energy loss due to wave breaking are not known the linearised equations of motion are used and energy loss is parameterised accordingly to describe the evolution of tsunami impulse in shallow water the hilbert transform technique was introduced it facilitates considerably the evaluation of the tsunami impulse transformation its run up and coast inundation range examples are included to illustrate the applicability of the theoretical derivations

oceanic propagation of a potential tsunami from the la palma island 1 the likelihood of a large scale tsunami from the la palma island is considered small by most nevertheless the potential catastrophic consequences call for attention here we report on numerical simulations of a tsunami that might result from the extreme case of a flank collapse of the cumbre vieja volcano at the la palma island done by combining a multimaterial model for the wave generation with boussinesq models for the far field propagation our simulations show that the slide speed is close to critical effectively generating an initial wave of several hundred meters height our main focus is the wave propagation which is genuinely dispersive in the far field propagation becomes increasingly complex due to the combined effects of dispersion refraction and interference in the direction of propagation constructive interference of the trailing waves are found to decrease the decay of the maximum amplitude with distance compared to classical asymptotic theory at transatlantic distances thus the commonly used hydrostatic models fail to describe the propagation consequences of the la palma scenario would be largest at the canary islands but our findings also suggests that the whole central atlantic would face grave consequences however the largest surface elevations are smaller than the most pessimistic reports found in literature we also find undular bores towards the shorelines of america

sources and flow patterns of deep ocean waters as deduced from potential temperature salinity and initial phosphate concentration through the deconvolution of ocean chemical data it has been shown that the ratio of o2 utilization to phosphate production in the sea is 175 6 rather than 138 as proposed by redfield et al 1963 we find no evidence that this ratio changes significantly with location or depth in the sea we have used this new ratio to calculate the initial phosphate concentrations for the waters sampled during the geosecs and tto programs the important application of these new results is in constraining the origin and flow patterns of deep waters in the ocean we believe that a strong case can be made that antarctic salinity maximum water i e the common water of montgomery 1958 is produced by the mixing of waters entering the antarctic from mid depths in the indian pacific and atlantic with weddell sea bottom water southern component antarctic common water consists of about 45 weddell sea bottom water 30 intermediate waters from the pacific and indian oceans and 25 deep water originating from the northern atlantic

cd ca changes in a deep cape basin core over the past 730 000 years response of circumpolar deepwater variability to northern hemisphere ice sheet melting a comparison of cadmium calcium cd ca records of benthic foraminifera from a deep cape basin and a deep eastern equatorial pacific core suggests that over the past 400 000 years the nutrient concentration of circumpolar deep water cpdw has always been lower than that of the deep pacific the data further suggest that at the 100 000 and 23 000 year orbital periods the contribution of north atlantic deep water to cpdw is at a maximum during periods of ice growth and at a minimum during periods of ice decay these results are not in agreement with results based on carbon isotope records of benthic foraminifera which suggest intervals of cpdw nutrient enrichment relative to the deep pacific and an approximately in phase relationship between cpdw nutrient concentration and ice volume resolution of the apparent conflict between 13c and cd ca data may provide important constraints on past deep ocean circulation and nutrient variability

deep thermohaline circulation in the low latitude atlantic during the last glacial present day low latitude eastern and western atlantic basins are geochemically distinct below the sill depth of the mid atlantic ridge while antarctic bottom water aabw circulates freely in the western atlantic flow into the eastern atlantic is restricted below 4 km which results in filling the abyssal depths of this basin with water of geochemical similarity to nutrient depleted north atlantic deep water using carbon isotopes and cd ca ratios in benthic foraminifera we reconstruct the geochemistry of these basins during the last glacial maximum results indicate that deep eastern and western atlantic basins became geochemically identical during the last glacial this was achieved by shoaling of the upper surface of aabw above the sill depth of the mid atlantic ridge which allowed bottom waters in both basins to be filled with the same water mass although aabw became the dominant water mass in the deep eastern atlantic basin during the glacial holocene glacial 13c po4 shifts in this basin are in redfield proportions unlike the disproportionate holocene glacial 13c po4 shifts observed in the southern ocean by examining the composition of deep and intermediate waters throughout the atlantic we show that this effect was induced by a change in gradient of the 13c po4 deepwater mixing line during glacial times evidence from high latitude planktonic data suggests that the change in gradient of the deepwater mixing line was brought about through a significant reduction in the thermodynamic effect on southern ocean surface waters by using coupled 13c po4 data to constrain the composition of end member water masses in the glacial atlantic we conclude that deep waters in the low latitude glacial atlantic were composed of a mixture of northern and southern source waters in a ratio of 1 3

tsunamis generated by long and thin granular landslides in a large flume in this experimental study granular material is released down slope to investigate landslide generated waves starting with a known volume and initial position of the landslide source detailed data are obtained on the velocity and thickness of the granular flow the shape and location of the submarine landslide deposit the amplitude and shape of the near field wave the far field wave evolution and the wave runup elevation on a smooth impermeable slope the experiments are performed on a 6 7 m long 30 slope on which gravity accelerates the landslides into a 2 1 m wide and 33 0 m long wave flume that terminates with a 27 runup ramp for a fixed landslide volume of 0 34 m3 tests are conducted in a range of still water depths from 0 05 to 0 50 m observations from high speed cameras and measurements from wave probes indicate that the granular landslide moves as a long and thin train of material and that only a portion of the landslide termed the effective mass is engaged in activating the leading wave the wave behavior is highly dependent on the water depth relative to the size of the landslide in deeper water the near field wave behaves as a stable solitary like wave while in shallower water the wave behaves as a breaking dissipative bore overall the physical model observations are in good agreement with the results of existing empirical equations when the effective mass is used to predict the maximum near field wave amplitude the far field amplitude and the runup of tsunamis generated by granular landslides

field survey and numerical simulations a review of the 1998 papua new guinea tsunami the papua new guinea png tsunami of 1998 is re examined through a detailed review of the field survey as well as numerous numerical computations the discussion of the field survey explores a number of possible misinterpretations of the recorded data the survey data are then employed by a numerical model as a validation tool a boussinesq model and a nonlinear shallow water wave nlsw model are compared in order to quantify the effect of frequency dispersion on the landslide generated tsunami the numerical comparisons indicate that the nlsw model is a poor estimator of offshore wave heights however due to what appears to be depth limited breaking seaward of sissano spit both numerical models are in agreement in the prediction of maximum water elevations at the overtopped spit by comparing three different hot start initial profiles of the tsunami wave it is shown that the initial shape and orientation of the tsunami wave is secondary to the initial displaced water mass in regard to prediction of water elevations on the spit these numerical results indicate that agreement between numerical prediction of runup values with field recorded values at png cannot be used to validate either a nlsw tsunami propagation model or a specific landslide tsunami hot start initial condition finally with the use of traditional tsunami codes a new interpretation of the png runup measurements is presented

similar rates of modern and last glacial ocean thermohaline circulation inferred from radiochemical data today the ocean thermohaline circulation transports half of the 231pa produced by radioactive decay in the atlantic ocean water column to the southern ocean this export respectively imparts low and high 231pa 230th ratios to the surface sediments of these oceans ocean sediments from the last glacial maximum bear a similar isotopic fingerprint implying that advection of north atlantic deep intermediate water into the circumpolar deep water of the southern ocean occurred at a similar or slightly higher rate during the last glacial period

slope failures on the flanks of the western canary islands abstract landslides have been a key process in the evolution of the western canary islands the younger and more volcanically active canary islands el hierro la palma and tenerife show the clearest evidence of recent landslide activity the evidence includes landslide scars on the island flanks debris deposits on the lower island slopes and volcaniclastic turbidites on the floor of the adjacent ocean basins at least 14 large landslides have occurred on the flanks of the el hierro la palma and tenerife the majority of these in the last 1 million years with the youngest on the northwest flank of el hierro as recent as 15 thousand years in age older landslides undoubtedly occurred but are difficult to quantify because the evidence is buried beneath younger volcanic rocks and sediments landslides on the canary island flanks can be categorised as debris avalanches slumps or debris flows debris avalanches are long runout catastrophic failures which typically affect only the superficial part of the island volcanic sequence up to a maximum thickness of 1 to 2 km they are the commonest type of landslide mapped in contrast slumps move short distances and are deep rooted landslides which may affect the entire thickness of the volcanic edifice debris flows are defined as landslides which primarily affect the sedimentary cover of the submarine island flanks some landslides are complex events involving more than one of the above end member processes individual debris avalanches have volumes in the range of 50 500 km3 cover several thousand km2 of seafloor and have runout distances of up to 130 km from source overall debris avalanche deposits account for about 10 of the total volcanic edifices of the small relatively young islands of el hierro and la palma some parameters such as deposit volumes and landslide ages are difficult to quantify the key characteristics of debris avalanches include a relatively narrow headwall and chute above 3000 m water depth on the island flanks broadening into a depositional lobe below 3000 m debris avalanche deposits have a typically blocky morphology with individual blocks up to a kilometre or more in diameter however considerable variation exists between different avalanche deposits at one extreme the el golfo debris avalanche on el hierro has few large blocks scattered randomly across the avalanche surface at the other icod on the north flank of tenerife has much more numerous but smaller blocks over most of its surface with a few very large blocks confined to the margins of the deposit icod also exhibits flow structures longitudinal shears and pressure ridges that are absent in el golfo the primary controls on the block structure and distribution are inferred to be related to the nature of the landslide material and to flow processes observations in experimental debris flows show that the differences between the el golfo and icod landslide deposits are probably controlled by the greater proportion of fine grained material in the icod landslide this in turn relates to the nature of the failed volcanic rocks which are almost entirely basalt on el hierro but include a much greater proportion of pyroclastic deposits on tenerife landslide occurrence appears to be primarily controlled by the locations of volcanic rift zones on the islands with landslides propagating perpendicular to the rift orientation however this does not explain the uneven distribution of landslides on some islands which seems to indicate that unstable flanks are a weakness that can be carried forward during island development this may occur because certain island flanks are steeper extend to greater water depths or are less buttressed by the surrounding topography and because volcanic production following a landslide my be concentrated in the landslide scar thus focussing subsequent landslide potential in this area landslides are primarily a result of volcanic construction to a point where the mass of volcanic products fails under its own weight although the actual triggering factors are poorly understood they may include or be influenced by dyke intrusion pore pressure changes related to intrusion seismicity or sealevel climate changes a possible relationship between caldera collapse and landsliding on tenerife is not in our interpretation supported by the available evidence

tsunami wave height dependence on landslide volume tsunami generation from submarine landslides depends mainly on the volume of the slide material and also on other factors which include angle of the slide water depth density of the slide material the speed with which the material moves duration of the slide etc based on an incomplete data set of volume v of slide versus maximum amplitude h of the resulting tsunami waves gleaned through available literature a simple linear regression relationship was developed another partial data set was developed also from published literature on v versus h values based on numerical models it was found that the agreement between the results of the numerical simulations and the observations is rather poor it is not clear why this is so and which data set is of questionable relevance this is not to cast doubt on numerical models that do not use volume of the slide in an explicit manner

on the effect of the water body geometry on landslide tsunamis physical insight from laboratory tests and 2d to 3d wave parameter transformation preliminary landslide tsunami hazard assessment is commonly based on empirical equations derived from wave channel 2d or wave basin 3d experiments the far field wave in 2d can easily be an order of magnitude larger than in 3d the present study systematically investigates the effect of the water body geometry on the wave characteristics in the near and far field subaerial landslide tsunami tests were conducted relying upon both a 2d and a 3d physical model undertaken with identical boundary conditions the test parameters included two water depths three rigid slides as well as various slide release positions empirical equations for 3d offshore and laterally onshore wave properties are presented and compared with previous work a direct comparison of the wave features reveals that the waves decay in 2d 3d onshore and 3d offshore with x 0 30 r 0 67 and r 1 0 where x 2d and r 3d describe the distance from the impact zone in 2d four wave types are observed whereas only the two least non linear types were observed in 3d this finding is further analysed with wavelet spectra for a large slide froude number f relative slide thickness s and relative slide mass m the 3d wave heights in the slide impact zone can be as large as in 2d however for small f s and m the 3d waves are considerably smaller both in the near and far field a novel method is presented and validated to transform data from 2d studies to 3d this method may have favourable implications on preliminary landslide tsunami hazard assessment

combinations of volcanic flank and seafloor sediment failure offshore montserrat and their implications for tsunami generation recent seafloor mapping around volcanic islands shows that submarine landslide deposits are common and widespread such landslides may cause devastating tsunamis but accurate assessment of tsunami hazard relies on understanding failure processes and sources here we use high resolution geophysical data offshore from montserrat in the lesser antilles to show that landslides around volcanic islands may involve two fundamentally different sources of sediment island flank and larger seafloor sediment failures and can occur in multiple stages a combination of these processes produces elongate deposits with a blocky centre associated with island flank collapse surrounded by a smoother surfaced deposit that is dominated by failed seafloor sediment the failure of seafloor sediment is associated with little marginal accumulation and involves only limited downslope motion submarine landslide deposits with similar blocky and smooth surfaced associations are observed in several locations worldwide but the complex emplacement processes implied by this morphological relationship can only be revealed by high resolution geophysical data such complexity shows that the volume of landslide deposits offshore of volcanic islands cannot simply be used in tsunami models to reflect a single stage collapse of primary volcanic material by applying predictive equations for tsunami amplitude to investigate general scenarios of volcanic island landslide generation we show that the tsunami hazard associated with volcanic island collapse remains highly significant volcanic flank failures even if relatively small may generate large local tsunamis but associated seafloor sediment failures even if they have a much greater volume have a substantially lower potential for tsunami generation

ritter island volcano lateral collapse and the tsunami of 1888 summary in the early morning of 1888 march 13 roughly 5 km 3 of ritter island volcano fell violently into the sea northeast of new guinea this event the largest lateral collapse of an island volcano to be recorded in historical time flung devastating tsunami tens of metres high on to adjacent shores several hundred kilometres away observers on new guinea chronicled 3 min period waves up to 8 m high that lasted for as long as 3 h these accounts represent the best available first hand information on tsunami generated by a major volcano lateral collapse in this article we simulate the ritter island landslide as constrained by a 1985 sonar survey of its debris field and compare predicted tsunami with historical observations the best agreement occurs for landslides travelling at 40 m s 1 but velocities up to 80 m s 1 cannot be excluded the ritter island debris dropped little more than 800 m vertically and moved slowly compared with landslides that descend into deeper water basal friction block models predict that slides with shorter falls should attain lower peak velocities and that 40 ms 1 is perfectly compatible with the geometry and runout extent of the ritter island landslide the consensus between theory and observation for the ritter island waves increases our confidence in the existence of mega tsunami produced by oceanic volcano collapses two to three orders of magnitude larger in scale

debris flow generated tsunamis and their dependence on debris flow dynamics abstract debris flow generated tsunamis can be extremely dangerous for lakeside settlements and infrastructure debris flow composition strongly affects debris flow thickness and velocity and therefore also the generated tsunami this interaction is however poorly understood we investigate the effects of debris flow volume composition gravel sand clay water and subaerial outflow slope on wave celerity and amplitude in a small scale physical model consisting of an inclined outflow channel which transits into a three dimensional water reservoir we find that upon debouching a debris flow pushes the water forward until wave celerity exceeds subaqueous debris flow velocity i e froude number wave celerity has the strongest relation with debris flow velocity debris flow velocity increases with increasing water and clay content up to 22 which both lubricate the flow far field leading wave amplitude has the strongest relation with debris flow momentum velocity times effective mass which is mostly a function of debris flow thickness water and clay content we test the applicability of published semi empirical equations for predicting tsunami amplitude generated by dry landslides and show that they are to some extent also applicable to debris flow potential scale effects especially considering the smallest waves and water depths could influence the applicability of these predictors and translation of the results to the field scale our results demonstrate the importance of debris flow composition on tsunami generation and evolution and thus the necessity of including flow composition in predictive simulation models

carbon isotope composition of tropical surface water during the past 22 000 years carbon isotope values of many species of planktonic foraminifera are size dependant values of 13c of individual size fractions are therefore an integration of low 13c values of calcite precipitated in the juvenile growth stage and high values precipitated in later stages in general the selection of a particular size fraction for downcore studies has been subjective analysis of different size fractions of planktonic foraminifera however yields different time series in downcore studies by measuring the 13c of many size fractions the 13c precipitated throughout the growth of the foraminifera can be calculated time series of the 13c of calcite precipitated in the late growth stages of planktonic foraminifera from two nearby cores from the caribbean sea result in a better correlation than time series of constant size fractions these 13c records indicate similar 13c values during the last glaciation and the late holocene and a broad deglacial minimum approximately synchronous with a minimum in the 13c records of benthic foraminifera from intermediate depth atlantic cores the deglacial minimum may be a reflection of the isotopic composition of the underlying intermediate water which may be affected by circulation changes or changes in preformed 13c values and or of the flux of water upwelled into the surface layer the small 0 2 to 0 0 glacial interglacial 13c difference in tropical surface water is also believed to be affected by the chemistry of the underlying source water

edge waves generated by the landslide on a sloping beach abstract a general solution of linear edge wave expressed in triple integral form is obtained for a landslide of an arbitrary shape on a uniformly sloping beach utilizing a reliable numerical integration package surface elevations are computed accurately results for various gaussian landslide shapes are presented by both numerical integrations and an asymptotic method along with numerical integration wave fields triggered by landslide motion with different shapes are strongly affected by the initial condition at the early phase but the initial difference decreases as time goes on the effect of double quadratic finite slide on the generated wave is analyzed some evidences for the edge wave behavior of a dispersive water wave are obtained in the present numerical experiments

experiments on slide generated waves in a 1 500 scale fjord model abstract an unstable rock slope is detected in akerneset located in storfjorden western norway in the future this rock slope will produce a slide and a subsequent tsunami in accordance to this future event experiments in a 1 500 scale model of the inner part of storfjorden are performed where the model geometry is made after the real fjord bathymetry while the slide is an idealized slide of block type the slide motion is monitored and the generated waves are measured at a number of wave gauges in the model at selected locations local details of the flow velocities and inundation are measured by digital image techniques and acoustic probes features of the wave system and the inundation are elaborately discussed with a view to the future event as well as to the application of models

experimental investigation of impact generated tsunami related to a potential rock slide western norway abstract two dimensional experiments of wave generation from the possible akneset rock slide have been performed using solid block modules in a transect with a geometric scaling factor of 1 500 the width of the slide model was kept fixed at 0 45 m the length of the blocks spanned from 1 to 2 m the thickness was either 0 12 or 0 16 m and the front angle was 45 maximum water depth was 0 6 m with the slide plane having an angle of 35 three different scenarios were studied only the run out side was modelled surface elevations at three locations outside the sloping region were measured with ultra sonic wave gauges and discussed in light of hydrodynamic wave theory particle image velocimetry piv was used to extract instantaneous velocity fields comparison is made between experimental velocity profiles and profiles consistent with a boussinesq theory high speed video of the impact was recorded and used to determine qualitative aspects of the forward collapse of the impact crater backfill wave

carbon and oxygen isotopic disequilibria of recent deep sea benthic foraminifera abstract the carbon and oxygen isotopic compositions of 149 samples of benthic foraminifera from deep sea core tops indicate that none of the nine species studied secrete calcium carbonate in isotopic equilibrium with ambient bottom water uvigerina pyrgo murrhina and oridorsalis tener are the closest to 18o equilibrium with average deviations about 0 4 while planulina wuellerstorfi and p murrhina are the closest to 13c equilibrium with average deviations about 1 p wuellerstorfi shows the most systematic relationship between 13c and bottom water apparent oxygen utilization the intraspecific variabilities in 18o and 13c suggest that estimates of bottom water paleotemperatures can be made to a precision of 0 7 c while estimates of past apparent oxygen utilization aou can be made to 35 mol kg based on intraspecific comparisons of the recent samples with fossils no temporal changes in the degree of either 18o or 13c disequilibrium have been detected for planulina wuellerstorfi uvigerina oridorsalis tener and globocassidulina subglobosa

cadmium zinc copper and barium in foraminifera tests the concentrations of cadmium zinc copper and barium have been determined on 2 mg samples of single species foraminifera populations cleaning techniques were tested using north atlantic core tops and followed by a detailed downcore study for the last 30 000 years in south atlantic core v22 174 raw foram tests cleaned by crushing followed by ultrasonic removal of fine grained material and dissolved in a ph 5 5 acetate buffer contain appreciable amounts of trace elements associated with ferromanganese and alumino silicate contaminants a reductive complexing cleaning treatment reduces ferromanganese contamination by 1 2 orders of magnitude acetate buffers at ph 5 5 complex iron and raise the solubility of ferromanganese oxides these buffers are unsuitable for separating carbonate lattice bound trace elements from the fraction associated with ferromanganese phases improved mechanical and ultrasonic reductive cleaning combined with a mild dissolution in distilled water under 1 atm pco2 reduces contaminant levels another order of magnitude the cd and zn concentrations order 10 8 mole cd mole ca and 10 5 mole zn mole ca of species with low surface area show an increase with decreasing isotopic temperatures this increase is consistent with the increasing concentrations of these metals from low values in surface waters to higher values at depth the variance of cd and zn over the last 30 000 years in the central south atlantic is consistent with the probable variability of the dissolved trace elements at the calcification levels of the species analyzed cu and ba are irreproducible and probably sensitive to residual contaminant phases the trace element content of the tests differs from levels observed in a recent coprecipitation study foraminifera may be a significant vector in zinc cycling in the ocean

waves generated by subaerial slides with various porosities abstract waves generated by subaerial slides were investigated experimentally in a two dimensional wave tank slide volume initial position slope angle and equilibrium water depth were kept constant while the slide material was varied five different slide types were employed one block slide and four granular slides with grain diameter ranging from 3 mm to 25 mm the slides were accelerated by gravity with different impact velocities and froude numbers varying from 0 34 to 0 93 amplitudes of the generated waves were measured with non intrusive acoustic wave gauges while the slide position during rundown was recorded with a high speed video camera empirical functions for prediction of maximum amplitudes that have been reported in the literature were employed for comparison with the generated waves differences between predictions based on the empirical functions and experimental results were discussed together with possible effects of permeability

rockslide tsunamis in complex fjords from an unstable rock slope at akerneset to tsunami risk in western norway abstract an unstable rock volume of more than 50 million m 3 has been detected in the akerneset rock slope in the narrow fjord storfjorden more romsdal county western norway if large portions of the volume are released as a whole the rockslide will generate a tsunami that may be devastating to several settlements and numerous visiting tourists along the fjord the threat is analysed by a multidisciplinary approach spanning from rock slope stability via rockslide and wave mechanics to hazard zoning and risk assessment the rockslide tsunami hazard and the tsunami early warning system related to the two unstable rock slopes at akerneset and hegguraksla in the complex fjord system are managed by aknes tafjord beredskap iks previously the aknes tafjord project the present paper focuses on the tsunami analyses performed for this company to better understand the effects of rockslide generated tsunamis from akerneset and hegguraksla two and three dimensional site specific laboratory experiments are conducted to study the generation propagation and run up of the wave for several potential rockslide scenarios from akerneset furthermore the two models globouss and dpwaves are applied for numerical simulations of the generation propagation phase and a third model most is applied for numerical simulations of the near shore propagation and inundation of the wave in selected locations strong emphasis is put on verification validation and sensitivity of the numerical models the best match between the numerical simulations and the laboratory experiments is found for the larger scenarios with the linear dispersive solution for the propagation phase the corresponding calculated run up values are remarkably similar to the ones observed during the laboratory experiments during the risk assessment it was found that the rockslide tsunami hazard probability of impact is higher than accepted by the norwegian planning and building act this should at that time prevent any further development in all the exposed areas of the entire fjord system the act is today altered to open for specified further development in the various hazard zones the results of the tsunami analyses are applied in risk management in terms of hazard map production and land use planning two failure scenarios for each of the two unstable rock slopes are designed for the hazard zoning the larger and less probable scenarios 1 in 5000 years are applied for evacuation zones and routes while the smaller and more probable scenarios larger than 1 in 1000 years are applied for location and design of less critical facilities accepted in the inundation zone

glacial and holocene stable isotope distributions in the southeastern indian ocean we have reconstructed glacial interglacial variations in cibicidoides wuellerstorfi 13c and 18o in the southeastern indian ocean using depth transects of cores from off western and southern australia we compare these new results with published stable isotope records to constrain glacial interglacial changes in indian ocean chemistry and circulation the strong last glacial maximum lgm deep water 13c depletions previously observed for the northeastern indian ocean did not extend throughout the low latitude glacial indian ocean we observe only a small lgm 13c decrease off southern australia in marked contrast to the strong lgm 13c depletions observed in many cores from the atlantic and western indian sectors of the southern ocean it is not yet clear whether the very low lgm 13c values in the deep northern and southwestern indian ocean are an artifact of surface ocean productivity or whether they reflect real gradients in deep water chemistry

authigenic cadmium enrichments in suboxic sediments precipitation and postdepositional mobility the postdepositional mobility of cd and u has been investigated in north atlantic turbidites in order to validate their utility as proxies of paleo organic carbon fluxes in this region pelagic sediments are interspersed with relatively organic rich turbidites following instantaneous emplacement of turbidite units an oxidation front progressively migrated downwards into the suboxic turbidite thereby leading to redistribution of authigenic phases according to their affinity to different redox conditions authigenic cd concentrations show a large peak at the redox boundary and are significantly lower in the oxidized portion than in the deeper unoxidized part of the turbidite this distribution indicates that cd has been continuously remobilized by the oxidation front thereby suggesting high sensitivity of the cd species to the redox state and an efficient immobilization mechanism for cd under reducing conditions we propose the precipitation of cds as a plausible mechanism for removal of cd in reducing sediments rather than adsorption onto mineral surfaces this proposal is consistent with porewater data indicating diffusion of cd toward and uptake by suboxic sediments solubility calculations suggest that precipitation of cds may occur in suboxic sediments in the presence of trace levels of h2s below routine detection limits there is no evidence for release of cd or u back into seawater upon oxidation of reducing sediments the strong coupling between precipitation of authigenic cd and u and the early diagenetic degradation of organic carbon offers the potential of reconstructing paleo productivity using records of cd and u however postdepositional redistribution of authigenic cd and u may significantly alter records of authigenic cd and u thereby rendering paleo productivity reconstructions uncertain we propose that the cd u authigenic ratio may provide a qualitative indicator to assess the relative role of steady state incorporation relative to transient burn down enrichments

geochemistry of magnesites and dolomites at the oberdorf laming austria deposit and implications for their origin the major and trace element geochemistry of magnesite and dolomite samples from alternating rock masses at the oberdorf laming styria austria mineralization has been studied the rare earth elements ree are considered to be of importance for the discussion of the origin of sparry magnesite deposits the al and ree contents are positively correlated indicating a clay component as the main source for ree in the magnesites and their precursor rocks our data support the view that the oberdorf and probably other magnesite mineralizations in the eastern alps have been formed by metasomatism through this process calcite which was deposited by sedimentation in a marine environment underwent dolomitization subsequently mg rich solutions circulating through the rock masses formed the magnesite bodies

estimating the topography before volcanic sector collapses using tsunami survey data and numerical simulations large sector collapses and landslides have the potential to cause significant disasters estimating the topography and conditions such as volume before the collapse is thus important for analyzing the behavior of moving collapsed material and hazard risks this study considers three historical volcanic sector collapses in japan that caused tsunamis the collapses of the komagatake volcano in 1640 oshima oshima island in 1741 and unzen mayuyama volcano in 1792 numerical simulations of the tsunamis generated by each event were first carried out based on assumed collapse scenarios the primary objective of this study is to present conditions related to the topography before the events based on inverse models of the topography from those results and tsunami survey data the oshima oshima tsunami which is the subject of many previous studies was first simulated to validate the model accuracy and evaluate how run up heights changed during the simulation as the topographic conditions changed the run up height was especially sensitive to the collapsed volume and frictional acceleration affecting the collapsed material however the observed run up heights could be reproduced with high accuracy using proper conditions of frictional acceleration for the scenarios even if they were not exact a minimum requirement for the collapsed volume to generate the observed run up height was introduced and quantitatively evaluated using the results of numerical tsunami simulations the minimum volumes of the collapses of the komagatake and unzen mayuyama volcanoes were estimated to be approximately 1 2 and 0 3 km3 respectively

physical modeling of tsunamis generated by three dimensional deformable granular landslides 1 tsunamis generated by deformable granular landslides are physically modeled in a three dimensional tsunami wave basin based on the generalized froude similarity the dynamic landslide impact characteristics were controlled by means of a novel pneumatic landslide generator the wave amplitudes periods and wavelengths are related to the landslide parameters at impact with the landslide froude number being a dominant parameter between 1 and 15 of the landslide kinetic energy at impact is converted into the wave train energy the wave amplitudes decay in radial and angular directions from the landslide axis the first wave crest mostly travels with speeds close to the theoretical approximation of the solitary wave speed the measured tsunami wave profiles were either of the nonlinear oscillatory or nonlinear transition type depending primarily on the landslide froude number and relative slide thickness at impact the generated waves range from shallow to deep water depth regimes with the majority being in the intermediate water depth regime wave characteristics are compared with other two and three dimensional landslide tsunami studies and the results are discussed

improved landslide tsunami prediction effects of block model parameters and slide model 1 subaerial landslide tsunamis and impulse waves are caused by mass movements impacting into a water body and the hazards they pose have to be reliably assessed empirical equations developed with physical froude model studies can be an efficient method for such predictions the present study improves this methodology and addresses two significant shortcomings in detail for the first time these are the effect of three commonly ignored block model parameters and whether the slide is represented by a rigid block or a deformable granular material a total of 144 block slide tests were conducted in a wave flume under systematic variation of three important block model parameters the slide froude number the relative slide thickness and the relative slide mass empirical equations for the maximum wave amplitude height and period as well as their evolution with propagation distance are derived for most wave parameters remarkably small data scatter is achieved the combined influence of the three block model parameters affects the wave amplitude and wave height by up to a factor of two the newly derived equations for block slides are then related to published equations for granular slides this comparison reveals that block slides do not necessarily generate larger waves than granular slides as often argued in the technical literature in fact it is shown that they may also generate significant smaller waves the new findings can readily be integrated in existing hazard assessment methodologies and they explain a large part of the discrepancy between previously published data

last glacial maximum paleochemistry and deepwater circulation in the southern ocean evidence from foraminiferal cadmium south atlantic benthic foraminiferal cd ca shows no glacial interglacial variation suggesting that the glacial contribution of north atlantic deep water to the southern ocean was not much different than at present in contrast cd ca in southeast indian ridge cores show lower glacial bottom water cd comparable to levels in intermediate depths of the north atlantic and significantly lower than in the deep south atlantic low glacial cd ca was also recorded in planktonic foraminifera suggesting a substantial decrease in the nutrient concentration of subantarctic surface water during the glacial maximum which most likely was caused by increased biological productivity the cd data are inconsistent with low glacial benthic foraminiferal 13c which suggest higher nutrient concentration we propose that the low cd ca in the southeast indian ridge records reflects a local source of nutrient depleted deepwater formed during the last glacial maximum by open ocean convection near the antarctic polar front downstream of the kerguelene plateau if this source was limited to the southeast indian basin then its impact on the overall chemistry of glacial circumpolar deepwater was rather small however if during glaciations open ocean convection became the dominant mode of bottom water formation it might have had a greater impact on cpdw chemistry

on the characteristics of landslide tsunamis this review presents modelling techniques and processes that govern landslide tsunami generation with emphasis on tsunamis induced by fully submerged landslides the analysis focuses on a set of representative examples in simplified geometries demonstrating the main kinematic landslide parameters influencing initial tsunami amplitudes and wavelengths scaling relations from laboratory experiments for subaerial landslide tsunamis are also briefly reviewed it is found that the landslide acceleration determines the initial tsunami elevation for translational landslides while the landslide velocity is more important for impulsive events such as rapid slumps and subaerial landslides retrogressive effects stretch the tsunami and in certain cases produce enlarged amplitudes due to positive interference in an example involving a deformable landslide it is found that the landslide deformation has only a weak influence on tsunamigenesis however more research is needed to determine how landslide flow processes that involve strong deformation and long run out determine tsunami generation

the influence of air and sea exchange on the carbon isotope distribution in the sea we explore here the influence of the temperature dependence of isotope fractionation between atmospheric co2and ocean co2 on the distribution of carbon isotopes in the ocean this is accomplished by an analysis of departures from the expected redfield tie between po4 and 13c we find that for the surface ocean the temperature influence largely compensates for the biologic influence in the deep ocean the temperature influence imprinted at the sites of deepwater formation reduces somewhat the biologically induced difference between the carbon isotope ratios for deep waters produced in the northern atlantic and in the antarctic these same features are reproduced in the hamburg ocean model in order to assess the impact of changes in the ratio of ocean mixing rate to wind speed we have made a model run in which co2 exchange rates between air and sea were everywhere doubled as expected the influence of the thermodynamic effect on the oceanic carbon isotope distribution is magnified

manganese carbonate overgrowths on foraminifera tests below the zone where manganese is remobilized as mn2 aq reductively cleaned foraminifera in deep sea sediments have much higher mnca than those in core tops and sediment traps mnca ranges from less than 20 10 6 in and above the mno2 maximum to as high as 700 10 6 in reducing panama basin sediments the most plausible explanation for this enrichment is that the tests are coated with mn carbonate overgrowths these coatings can account for a significant proportion of the mn in reduced deep sea sediments uptake of manganous ion by carbonate may explain the absence of mn nodules in areas of high carbonate accumulation extreme degrees of overgrowth can alter foram trace element values but this artifact can be avoided by avoiding foraminifera with high mn ca

glacial deep water geometry south atlantic benthic foraminiferal cd ca and δ13c evidence a depth transect of cores from 1268 to 3909 m water depth in the western south atlantic are ideally situated to monitor the interocean exchange of deep water and variations in the relative strength of northern and southern sources of deep water production benthic foraminiferal cd ca and 13c data suggest that glacial north atlantic intermediate water gnaiw extended at least as far south as 28 s in the western south atlantic the core of nutrient depleted water was situated at 1500 m above and below water masses with higher nutrient concentrations when examined in conjunction with published paired cd ca and 13c from intermediate depth cores from other basins it appears that the extent of gnaiw influence on the intermediate waters of the world s oceans was less than suggested previously differentiating among possible pathways for the glacial deep ocean 3 km requires a better understanding of the controls on cd ca and 13c values of benthic foraminifera

deep circulation of the north atlantic over the last 200 000 years geochemical evidence variations in the cadmium calcium ratio of north atlantic deep water are recorded in the fossil shells of benthic foraminifera the oceanic distribution of cadmium is similar to that of the nutrients hence the cadmium calcium ratio in shells records temporal variations in nutrient distributions data from a north atlantic sediment core show that over the past 200 000 years there has been a continuous supply of nutrient depleted waters into the deep north atlantic the intensity of this source relative to nutrient enriched southern waters diminished by about a factor of 2 during severe glaciations this evidence combined with carbon isotope data indicates that the continental carbon inventory may have been less variable than previously suggested

north atlantic thermohaline circulation during the past 20 000 years linked to high latitude surface temperature during a surface cooling event 10 000 to 12 000 years ago higher cd ca and lower 13c 12c ratios are observed in benthic foraminifera shells from rapidly accumulating western north atlantic sediments data from sediment cores show that marked nutrient depletion of intermediate waters occurs in association with reduced glacial north atlantic deep water flux it is proposed that cold high latitude sea surface temperatures enhance intermediate water formation at the expense of deep water formation

changes in east atlantic deepwater circulation over the last 30 000 years eight time slice reconstructions using 95 epibenthic 13c records eight time slices were reconstructed to trace the distribution of east atlantic deepwater and intermediate water masses over the last 30 000 years our results show that there have been three distinct modes of deepwater circulation near the stage 3 2 boundary the origin of north atlantic deep water nadw was similar to today mode 1 however after late stage 3 the source region of the nadw end member shifted from the norwegian greenland sea to areas south of iceland mode 2 a reduced nadw flow persisted during the last glacial maximum with constant preformed 13c values the nutrient content of nadw increased markedly near the azores fracture zone from north to south probably because of the mixing of upwelled antarctic bottom water aabw from below which then advected with much higher flux rates into the northeast atlantic later the spread of glacial meltwater over the north atlantic led to a marked short term ventilation minimum below 1800 m about 13 500 14c years ago mode 3 the formation of nadw recommenced abruptly north of iceland 12 800 12 500 years ago and reached a volume approaching that of the holocene in the younger dryas 10 800 10 350 years b p another short term shutdown of deepwater formation followed between 10 200 and 9 600 years b p linked to a further major meltwater pulse into the atlantic each renewal of deepwater formation led to a marked release of fossil co2 from the ocean the likely cause of the contemporaneous 14c plateaus over the last 9000 years deepwater circulation varied little from today apart from a slight increase in aabw about 7000 14c years ago it is also shown that the oxygenated mediterranean outflow varied largely independent of the variations in deepwater circulation over the last 30 000 years

discussion of experimental investigation of impact generated tsunami related to a potential rock slide western norway by g saelevik a jensen g pedersen coastal eng 56 2009 897 906 this paper is a discussion of saelevik et al 2009 their comparison between block and granular model results is described in more detail along with a discussion of five parameters which may be in general responsible for deviations between block and granular models new small scale physical model tests have been performed to support some of the statements made finally it is argued that the use of physical model testing based on simplified geometries are justified in practice and normally produce results that are considerably better than an order of magnitude

a biomineralization model for the incorporation of trace elements into foraminiferal calcium carbonate measurements of srca of benthic foraminifera show a linear decrease with water depth which is superimposed upon significant variability identified by analyses of individual foraminifera new data for cdca support previous work in defining a contrast between waters shallower and deeper than 2500 m measured element partition coefficients in foraminiferal calcium carbonate relative to sea water d have been described by means of a one box model in which elements are extracted by rayleigh distillation from a biomineralization reservoir that serves for calcification with a constant fractionation factor such that d 1 f 1 f where f is the proportion of ca remaining after precipitation a modification to the model recognises differences in element speciation the model is consistent with differences between dsr dba and dcd in benthic but not planktonic foraminifera depth variations in d for sr and ba are consistent with the model as are differences in depth variation of dcd in calcitic and aragonitic benthic foraminifera the shallower depth variations may reflect increasing calcification rates with increasing water depth to an optimum of about 2500 m observations of unusually lower dcd for some deep waters not accompanied by similar dsr or dba may be because of dissolution or a calcification response to a lower carbonate saturation state

evidence from southern ocean sediments for the effect of north atlantic deep water flux on climate evidence from southern ocean sediments for the effect of north atlantic deep water flux on climate