deposit from a giant wave on the island of lanai hawaii limestone bearing gravel the newly named hulopoe gravel blankets the coastal slopes on lanai the deposit which reaches a maximum altitude of 326 meters formerly was believed to have been deposited along several different ancient marine strandlines but dated submerged coral reefs and tide gauge measurements indicate that the southeastern hawaiian islands sink so fast that former worldwide high stands of the sea now lie beneath local sea level evidence indicates that the hulopoe gravel and similar deposits on nearby islands were deposited during the pleistocene by a giant wave generated by a submarine landslide on a sea scarp south of lanai

the fate and accumulation of bromide during playa salt deposition an example from lake frome south australia an advectivn diffusion model describing the distribution of br in porewaters underlying an accumulating deposit of halite on a playa lake can be used to predict the evolving composition of the accumulating salt growing as a result of evaporation the br cl ratio of the accumulating halite is proportional to the concentration or br at the surface of the brine body from which it is growing the evolution of interstitial br and therefore the composition of the accumulating salt is a function of 1 the diffusion coefficient of br in the brine saturated sediment 2 the advective velocity of the interstitial water 3 the initial concentration of br and cl at the onset of evaporation and 4 the distribution coefficient of br into the accumulating salt all of which can be estimated for the sediments and brines of lake frome south australia at lake frome the model is used to estimate mean evaporation rates for the salt covered surfaces which are found to be between 0 5 and 3 0 cm y these rates are lower than the rates estimated for the salt free surfaces of the lake by allison and barnes 1985 but are consistent with the expectation that groundwater input and therefore evaporation rates will be focused at the salt free lake margins rather than at the salt covered central regions of the playa and that the surface albedo of the salt covered zones will reduce energy penetration to the sediment and thus evaporation

arid zone groundwater recharge and salinisation processes an example from the lake eyre basin australia in arid central australia the 1 14 m km2 endorheic lake eyre basin leb experiences sporadic floods and contains saline shallow groundwater in this basin where on ground physical and chemical data are very sparse new observations of major ion chemistry stable isotopes 2h 18o 13c radiogenic isotopes 3h 14c and remote sensing modis data were used to investigate groundwater recharge and salinisation processes in 2006 2007 in january 2007 there was a large and intense local rainfall event followed by flooding to the normally dry lake eyre resulting from heavy rainfall in the northern leb that took 2 months to arrive at lake eyre groundwater chemistry from this study show no evidence of recharge from the floodwaters or the local rainfall however this does not preclude the process low transit times and low infiltrating volumes may mean that the recharge event has not yet been detected over the longer term the stable isotope chemistry indicates that groundwater is predominantly diffusely recharged during heavy local rainfall events 100 150 mm month and radiogenic isotopes reflect an older shallow groundwater efficiently mixing with recent decadal recharge the high total dissolved solids tds of regional shallow groundwater up to 52 5 g l is intrinsically linked with these recharge processes where infiltrating diffuse rainfall is evaporated and heavy rainfall events transport saline pore water saline due to evaporation in the unsaturated zone to the groundwater system the high tds of shallow groundwater beneath the dry lake eyre bed up to 322 g l is also controlled by evaporation however although evaporite minerals are prolific in the lake area the non conservative behaviour of br in pore water limits analysis of the role of halite mineral dissolution and precipitation reactions controlling groundwater salinity evaporation driven salinisation of shallow groundwater in arid central australia is distinct from the transpiration driven salinisation of groundwater in the australian murray basin located in a semi arid climate and results in relatively high groundwater salinity values compared with many other large arid zone endorheic basins across the world

quaternary paleolake nutrient evolution and climatic change in the western qaidam basin deduced from phosphorus geochemistry record of deep drilling core sg 1 abstract phosphorus p provides an important biologically limiting nutrient in lake ecosystems and its concentrations furnish significant information on lake nutrient status climatic change and landscape development within a drainage area this study explores the potential of calcium bound p and iron bound p in calcareous lacustrine sediments to reveal variations of the paleolake nutrient status and its related climatic changes data come from the nearly 1000 m long core sg 1 from the western qaidam basin ne tibetan plateau which has been well dated by paleomagnetism to between 2 77 and 0 1 ma calcium bound p and iron bound p make up the two most frequent phases of inorganic phosphorus pools in the calcareous sediment this study compares the variations of calcium bound p and iron bound p with the independent proxy for biologic production proxy total organic carbon toc as well as a climatic proxy for lake level fluctuation from the borehole those results indicate that calcium bound p responds sensitively to paleolake nutrients and climatic changes while the iron bound p responds to more complex factors more specific to the content of iron oxides variations of the calcium bound p in the core sg 1 show a long term stepwise decrease with shifts at 2 5 ma 1 8 ma 1 2 ma and 0 6 ma indicating a long term stepwise decrease of the paleolake nutrient supply in the drainage this suggests that the ecologic systems experienced a long term deterioration and the climate in central asia became increasingly arid since after the late pliocene

estimation of evaporation from the normally dry lake frome in south australia depth profiles of deuterium composition expressed as delta values have been used to make point estimates of evaporation from the floor of the normally dry lake frome a salt lake in northern south australia values from five sites varying between 90 and 230 mm yr 1 have been used to obtain a relatively crude approximation for mean evaporation rate from the lake of 170 mm yr 1 under the assumption that this represents discharge of water from the regional groundwater system the groundwater inflow into the lake is calculated as 5 108 m3 yr 1 two possible models which describe groundwater inflow into the lake are discussed

boulders as a signature of storms on rock coasts this paper is the first review of coastal boulder studies it serves as a peer reviewed introduction to a special issue on the topic of boulders as a signature of storms on rock coasts since 2004 and the indian ocean tsunami most coastal boulder research has been focused on using boulders as sedimentary signatures of palaeo tsunami events and the most commonly used transport equations typically suggest that large boulder deposits are products of tsunami rather than storms there is growing empirical evidence demonstrating on inter annual to century timescales that storm waves are capable of transporting and depositing boulders of significant size at elevations well above sea level current process studies of how boulders are eroded transported and deposited have not received wide attention by rock coast geomorphologists or palaeoenvironmental reconstruction scientists this special issue is framed around the goal of highlighting our current understanding of the role of storm waves as a driving mechanism for boulder erosion transport and deposition here we review the current state of knowledge about boulder dynamics boulder responses to storms and boulders as sedimentary signatures of storm events we identify gaps in our conceptual and quantitative understanding lastly we propose means of addressing research gaps improving consistency between researchers and collecting multi purpose data this review and the papers contained within the special issue provide an improved understanding of coastal dynamics particularly the role storms can play in influencing erosion rates and depositional patterns of coarse material i e boulders or larger which has hitherto been under represented in the literature

boulders transport by catastrophic waves along the ionian coast of apulia southern italy abstract several tracts of the ionian coast of apulia southern italy are characterized by large boulders up to 80 t in weight scattered some meters above present sea level the largest boulder is about 80 t in weight and slid for about 40 m from the mean sea level up to about 1 8 m of altitude elongated boulders show a remarkably narrow range of orientation of the long axis as well as of the imbrication axis suggesting that they had been transported by a single catastrophic event most likely a tsunami connected to a wave train approaching the coast from the south stratigraphic morphological and historical data suggest that this event occurred during the late holocene conventional radiocarbon age determination performed on lithophag shells collected from a large boulder yielded a calibrated age between 1421 and 1568 a d then the catastrophic wave train probably a tsunami could be a local effect of the strong earthquake which hit southern italy on december 5th 1456

bonaire s boulder fields revisited evidence for holocene tsunami impact on the leeward antilles abstract supralittoral boulders and blocks are prominent sedimentary features along rocky shorelines worldwide in most cases their deposition is attributed to high energy wave events tsunamis severe storms even though tsunami waves are expected to have higher transport capacities compared to storm waves megaclasts of up to 100 t were observed to have been moved laterally by the latter waveform the deduction of certain extreme wave events tsunamis severe storms from the boulder record thus remains a major challenge in palaeo event research the debate on their differentiation is ongoing at the eastern coast of bonaire leeward antilles in the southern caribbean numerous limestone blocks and boulders up to c 130 t are distributed on top of a 3 6 m a s l above mean sea level palaeo reef platform disagreement exists among a number of authors concerning the transport processes involved in the formation of the boulder fields in this paper state of the art modelling approaches of coastal boulder entrainment and transport were applied in order to provide new and more reliable data to support challenge the working hypothesis of tsunami deposition to improve the reliability of the boulder transport model more realistic input parameters were provided by new dgps measurements of the boulder dimensions and the calculation of bulk densities by taking into account the heterogeneity of the reef rock boulders existing hydrodynamic equations were modified to allow for the irregular shape and real dimensions of the boulders the results indicate that i boulder weight and dimension and thus ii calculated wave energy and wave heights were overestimated in most of the previous studies where calculations of boulder volume were based on multiplication of the main axes the results of this study and wave heights observed during recent severe tropical cyclones seem to rule out storm generated waves for the dislocation of the largest blocks however the majority of coarse clast deposits may have been generated by periodic hurricane swells the results underline the significance of more realistic field data in modelling boulder transports by waves

numerical analysis of boulder transport by the 2004 indian ocean tsunami at pakarang cape thailand at pakarang cape thailand we conducted field observations and numerical modeling of the spatial and grain size distributions and sources of boulders deposited by the 2004 indian ocean tsunami the boulders are a very rare example of boulders for which a tsunami origin is well confirmed numerical modeling of the tsunami s boulder transport revealed that the grain size and spatial distributions of boulders are explainable by the initial distribution of boulders at the source and the tsunami s local behavior which is controlled strongly by the tsunami hydrodynamic features and local topography soon after the bore front reached at the beach the tsunami s hydraulic force on the tidal bench decreased suddenly below the critical force necessary to displace the boulder because of the seaward propagation of the reflected wave that had been generated at the beach slope consequently all boulders were deposited below the high tide line and subsequently concentrated at the western coast of the cape absence of boulders that had been originally deposited deeper than 10 m water depth is also explained by this reflected wave because the wave passed over boulders that had been originally deposited at 10 m water depth before the boulder crossed the reef edge our well tuned model elucidates how the tsunami was able to deposit large boulders on the tidal bench at the cape the results demonstrate that theoretically up to 250 tons of boulders might have been emplaced on the tidal bench by the 2004 indian ocean tsunami at the cape approximately 7 m wave height the calculated maximum weight is of comparable order to that of boulders around the world that are inferred to be of tsunami origin although we infer that the weight is determined based on the sensitive balance of the local topography hydrodynamic features of the tsunami and the initial distribution of boulders at the source

boulder deposits from large waves during the last interglaciation on north eleuthera island bahamas abstract seven boulders measuring 100 to 1000 m 3 are scattered along the coastal ridge of north eleuthera some are situated on ridge crests up to 20 m above present sea level the boulders were probably deposited during oxygen isotope substage 5e or 5d as shown by their stratigraphic setting and by amino acid racemization ratios d alloisoleucine l isoleucine ratios were determined for land snails and oolite of both marine and eolian origin was associated with the boulders like the boulders the probable source rocks exposed in the adjacent cliffs are composed of marine and eolian limestone of oolitic and peloidal composition the source beds are correlated with stage 9 or 11 the largest boulder is about 10 times the size of the largest holocene ones moved by waves in the area tsunamis are a reasonable possibility as a transporting mechanism of the pleistocene boulders however if deposited instead by storms during the last interglaciation the storms were of much greater intensity than those occurring in the region during the late holocene

reply to comments by kelletat 2008 comments to dawson a g and stewart i 2007 tsunami deposits in the geological record sedimentary geology 200 166 183

characteristics and hydrodynamics of boulders transported by storm waves at kudaka island japan abstract this study investigates the size position and the long axis orientation of 210 boulders at kudaka island japan these boulders were deposited from the reef crest to the slope of the back reef moat distributed within 275 m from the reef edge most boulders were rectangular to ellipsoidal without sharp broken edges they are reef rock fragments estimated as

tropical cyclone activity and western north atlantic stratification over the last millennium a comparative review with viable connections tropical cyclones tc are recognized to modify the thermal structure of the upper ocean through the process of vertical mixing assessing the role this mixing plays in the overall stratification of the upper ocean is difficult due to the relatively short and incomplete instrumental record proxy records for both tc landfalls and oceanographic stratification are preserved within the geological record and provide insight for how past changes in tc induced mixing have potentially affected water column structure prior to the instrumental record here we provide the first comparison between previously published paleo reconstructions of vertical ocean density and tropical cyclone activity from the western north atlantic a prominent lull in tc activity has been observed prior to approximately 1700 ce that extends back several centuries this interval of low tc activity is shown to be concurrent with the timing of increased ocean stratification near great bahama bank potentially due in part to reduced tc induced mixing to test whether this relationship is feasible we present numerical results from a coarse resolution ocean general circulation model experiment isolating the effect of tc surface wind forcing on the upper ocean an anomaly of roughly 0 12 kg m 3 in vertical stratification occurs above and below the mixed layer for model runs with and without tc mixing this anomaly is roughly 25 of the entire paleo density signal observed just prior to 1700 ce these results suggest that tc mixing alone cannot completely explain the density anomaly observed prior to 1700 ce but support tc variability as an important contributor to enhancing oceanic stratification during this interval copyright 2011 john wiley sons ltd

coastal stratigraphies of eastern bonaire netherlands antilles new insights into the palaeo tsunami history of the southern caribbean abstract a sediment record of three alluvial sites along the east and northeast oriented shore of bonaire netherlands antilles provides evidence for the recurrence of several extraordinary wave impacts during the holocene the interpretation of onshore high energy wave deposits is controversially discussed in recent sedimentary research however it represents a powerful tool to evaluate the hazard of tsunami and severe storms where historical documentation is short and or fragmentary a facies model was established based on sedimentary and geochemical characteristics as well as the assemblage and state of preservation of shells and shell fragments radiocarbon data and the comparison of the facies model with both recent local hurricane deposits and global tsunami signature types point to the occurrence of three major wave events around 3300 2000 1700 and shortly before 500 bp since i the stratigraphically correlated sand layers fulfill several sedimentary characteristics commonly associated with tsunamis and ii modern strong hurricanes left only little or even no sediment in the study areas they were interpreted as tsunamigenic however surges largely exceeding the energy of those accompanying modern hurricanes in the southern caribbean cannot entirely be ruled out the results are partially consistent with existing chronologies for holocene extreme wave events deduced from supralittoral coarse clast deposits on aruba bonaire and curacao as well as overwash sediments from cayo sal venezuela

cliff top megaclast deposits of ireland a record of extreme waves in the north atlantic storms or tsunamis past occurrences of major tsunami in the global record have often been inferred from the presence of megaclast accumulations at significant heights above sea level which sometimes exhibit a pronounced seaward directed imbricate fabric the aran islands off the west coast of ireland exist in a marine environment which is totally unprotected from the most extreme sea states encountered in the north atlantic spectacular megaclast accumulations are found along the tops of vertical cliffs on these islands the elevation of these deposits varies from 0 m to 50 m above mean sea level and they include clasts weighing 250 tonnes at sea level over 117 tonnes at 12 m and 2 9 tonnes at 50 m above sea level imbrication measurements on these megaclasts indicate a well defined and consistent mean direction from the southwest for the emplacing waves one that is consistent with the prevalent storm wind direction for the area the megaclast accumulations are subject to episodic and on going erosion by cliff retreat but the existing accumulations are estimated to record events since at least 1839 recent emplacement and reworking is evidenced by trapped plastic detritus within the deposits and eyewitness accounts of large storms during which clasts have been emplaced similar deposits are found on the exposed coasts of the shetland and orkney islands off scotland there is at present no evidence of any tsunami in recorded history affecting the western irish and scottish coasts other than those generated by the lisbon earthquake of 1755 where the wave effects were slight thus the presence of megaclast accumulations at significant heights above sea level on exposed coasts and exhibiting imbrication should not be used as a definitive criterion for the past occurrence of tsunami these deposits attest to extreme wave conditions occasionally encountered in the north atlantic and act as a record of such events extending back at least 160 years such data on extreme wave conditions are essential for the prediction of the effects of deepwater waves on structures such as offshore drilling platforms

extremely high energy wave deposits inside the great barrier reef australia determining the cause tsunami or tropical cyclone abstract a hydrodynamic approach is used to determine whether tsunami or cyclone generated waves were responsible for the deposition of fields of well imbricated rock boulders up to 290 tonnes along the coast of cairns inside the great barrier reef australia calculations of the overturning moments show that only tsunami are capable of moving such large boulders in this environment it is hypothesised that large tsunami 11 m have been able to penetrate the great barrier reef through wide 5 10 km 50 70 m deep passages between individual reefs three such passages each approximately 35 km apart and oriented in the same direction exist in the cairns region it is possible that these passages have funnelled and amplified palaeotsunamis the preferential location of eroded coral boulders up to 3 m in length on reef flats alongside these passages and their absence on other reefs throughout the region provide further evidence that extremely high energy waves have been able to penetrate the great barrier reef into the inner channel adjacent to the mainland carbon 14 ages of the coral boulders on these reef flats matches closely the ages of coral fragments pinned below the very large rock boulders along the coast these ages suggest that the cairns region has experienced large tsunami twice over the last millennium

numerical simulation of the december 1997 debris avalanche in montserrat lesser antilles emplacement of a debris avalanche in the white river valley of southern montserrat lesser antilles on 26 december 1997 was caused by sector failure of the south flank of the active soufriere hills volcano pre and post emplacement surveys of the region indicate a debris avalanche deposit volume of about 40 50 106 m this avalanche is modeled as the gravitational flow of a homogeneous continuum governed by a basal friction law mass and momentum equations are depth averaged over the slide thickness numerical results show that the observed distribution of debris and duration of emplacement is simulated well for a coulomb type friction law with a dynamic friction coefficient dependent upon the thickness and the velocity of the flowing mass

the role of porosity in discriminating between tsunami and hurricane emplacement of boulders a case study from the lesser antilles southern caribbean coastal boulder deposits are a consequence of high energy wave impacts such as storms hurricanes or tsunami parameters useful for distinguishing between hurricane and tsunami origins include distance of a deposit from the coast boulder weight and inferred wave height in order to investigate the role of porosity on boulder transport and elucidate the distinction between tsunami and hurricane impacts we performed archimedean and optical 3d profilometry measurements for the determination of accurate physical parameters for porous reef and coral limestone boulders from the islands of aruba bonaire and curacao abc islands netherlands antilles leeward islands subsets of different coral species and lithotypes constituting the boulders were sampled the physical parameters of boulders were analyzed and each boulder component was attributed to a certain range of porosity and density lowest porosities were observed in calcarenite 5 8 whereas highest porosities were measured for serpulid reef rock 47 68 porous serpulid reef rock 0 8 1 2 g cm 3 and the coral diploria sp 0 6 1 0 g cm 3 possess the lowest bulk densities while less porous calcarenite 2 0 2 7 g cm 3 and the coral montastrea cavernosa yield the highest bulk density values 1 6 2 7 g cm 3 the obtained physical parameters were used to calculate boulder weights and both hurricane and tsunami wave heights necessary to initiate transport of these boulders boulders are up to 5 6 times lighter than given in previously published data and hence required minimum hurricane or tsunami waves are lower than hitherto assumed the calculated wave heights the high frequency of tropical storms and hurricanes in the southern caribbean and the occurrence of boulders exclusively on the windward sides of the islands implicate that for boulders on the abc islands a hurricane origin is more likely than a tsunami origin 2008 elsevier b v all rights reserved

exploring typhoon variability over the mid to late holocene evidence of extreme coastal flooding from kamikoshiki japan sediment cores from two coastal lakes located on the island of kamikoshiki in southwestern japan lake namakoike and lake kaiike provide evidence for the response of a backbarrier beach system to episodic coastal inundation over the last 6400 years sub bottom seismic surveys exhibit acoustically laminated parallel to subparallel seismic reflectors intermittently truncated by erosional unconformities sediment cores collected from targeted depocenters in both lakes contain finely laminated organic mud interbedded with coarse grained units with depths of coarse deposits concurrent with prominent seismic reflectors the timing of the youngest deposit at kamikoshiki correlates to the most recently documented breach in the barrier during a typhoon in 1951 ad assuming that this modern deposit provides an analog for identifying past events paleo typhoons may be reconstructed from layers exhibiting an increase in grain size a break in fine scale stratigraphy and elevated sr concentrations

a quasi experimental setting of coarse clast transport by the 2010 chile tsunami bucalemu central chile abstract on 27th february 2010 a mw 8 8 earthquake occurred in central chile causing a tsunami that severely affected the central chilean coast in this study we present sedimentological data of the 2010 chile tsunami from the coastal town of bucalemu in central chile the tsunami deposited both fine grained sediments as well as cobbles and boulders the location offers a quasi experimental setting for coarse clast transport because an artificial pile of cobbles and boulders was piled there for construction purposes some days before the tsunami therefore the pre tsunami transport setting and transport distances are well defined additionally a local flow depth of ca 2 m and flow speed of ca 5 6 m s are deduced from eyewitness reports and video recordings the cobbles and boulders have been transported up to 155 m from the pile in landward direction the size of the quarried clasts was restricted to max 0 3 m3 and 720 kg bigger boulders were not available at the location even though calculations show that the tsunami would have been capable to transport them calculations of flow speeds required for the initialization of transport in different modes such as sliding rolling or saltation indicate that all clasts that were moved by the tsunami in landward direction were entrained by the flow given a minimum observed speed of 5 6 m s with 65 being transported by rolling and 35 by saltation the transported clasts are arranged in three groups positioned in morphological depressions on the coastal plain a landward fining trend is not present the arrangement of clasts originating from a pile and being deposited in distinctive groups entails that the landward transport of cobbles and boulders is a function of repeated entrainment transport and deposition by several waves of the tsunami wave train consequently we interpret the clast distribution as a result of a combination of the number of individual waves of the tsunami wave train their respective energies the local topography and the pre transport setting of a clast pile which releases wedged clasts with each successive wave

numerical models of tsunami sediment transport current understanding and future directions abstract researchers who study tsunami deposits share common ultimate goals of their work which are to better assess the magnitude information of paleotsunamis and to contribute to the assessment of future tsunami risks numerical modeling of tsunami sediment transport is an important piece of interdisciplinary research that fills the gap between geological studies and practical utilization of tsunami deposits forward and inverse numerical models that address tsunami transport of sand and boulders have been developed over the last two decades forward models are capable of delineating the time evolution of tsunami hydrodynamics sediment transport and the resulting morphological changes associated with erosion and deposition inverse models estimate tsunami characteristics such as flow speed and depth from deposits numerical modeling can be used not only to quantify paleotsunamis but also to enhance our understanding of tsunami sedimentology and hydrodynamics to make progress towards the ultimate goal of improved tsunami risk assessment development of an in depth mutual understanding between modelers and geologists of the advantages limitations and uncertainties in both numerical modeling and geological records is an important challenge

stable imbrication and delicate unstable settings in coastal boulder deposits indicators for tsunami dislocation abstract medium sized and coarse debris pebbles and boulders can exhibit patterns of setting particularly if they are elongated or tabular these patterns such as imbrication indicate certain transport processes mostly as to direction and character many years of observation and measuring of coarse coastal deposits are the basis for the conclusions presented here on environmental transport processes their character and their energy beside imbrication special emphasis is given to unstable or delicate settings of large boulders that evidently have remained in these positions from hundreds to thousands of years this deserves an explanation to how they arrived at these positions and why they have not changed into a more stable position given an environment of constant energy input along coastlines the discussion lays emphasis on whether both settings of mega boulders can be indicative of tsunami transport processes

large boulder deposits by tsunami waves along the ionian coast of south eastern sicily italy abstract the ionian coast of south eastern sicily between the towns of augusta and siracusa is characterized by the occurrence of anomalous calcareous boulders they are mostly scattered along large terraces located 2 5 m above sea level gently sloping towards the sea boulders are up to 182 t in weight and are arranged either in isolated elements or small groups composed of a few stacked elements several boulders show biogenic encrustations serpulids balanids lithophaga all over their surface which suggest that they were dragged from the mid sublittoral zone other boulders are partially covered by biogenic encrustations and show morphological features karstic pools exposed fracture surfaces suggesting that they were detached and scattered from the mid supralittoral zone direct observations on each boulder distance from the shoreline size and weight together with statistical analysis of the storm regime of the area allowed to operate hydrodynamic estimations useful to verify if tsunami or storm waves were responsible for their detachment and transport while radiocarbon age determinations on marine organisms constrained the timing collected data compared to historical catalogues suggest that in the last 1000 years three seismic events with local sources could have triggered tsunami waves associated with the boulder deposits occurring in the area the first two were probably triggered by the earthquakes of february 4 1169 and january 11 1693 which destroyed south eastern sicily according to geological data and numerical modelling the seismogenic source could be located in the ionian offshore between catania and siracusa the third tsunami was generated by the strong earthquake which took place in the strait of messina on december 28 1908

coral boulders on melekeok reef in the palau islands an indicator of wave activity associated with tropical cyclones abstract waves generated by tropical cyclones and tsunamis cause various impacts such as coastal erosion and damage to infrastructure the intensity of tropical cyclones will probably increase in the near future as a result of global warming therefore predicting the likely impacts of these storms is a prime concern boulder deposits are one of the key proxies that assist our understanding of previous tropical cyclones and tsunamis and are important if we are to accurately project their future impacts in december 2012 typhoon bopha hit the palau islands and many boulders were probably deposited on the east coast of babeldaob island during the event this area is one of the few locations where it is possible to distinguish between deposits that were generated by tropical cyclone waves and tsunamis this study records the distribution of boulders from the shore to the reef crest at melekeok reef on babeldaob island and evaluates the relationship between the movement of boulders and the hydraulic forces generated by the waves using a hydrodynamic model and wave calculations in addition this study projects the coastal impacts of tropical cyclone waves in the near future many boulders have been deposited on the reef crest within 100 m of the reef edge and the maximum weight of the boulders is 2 2 tons the boulders are composed of massive corals e g platygyra and they originated from the upper reef slope the results of the hydrodynamic modeling indicate that these boulders were transported and deposited by the waves generated by typhoon bopha significant wave height 8 7 m or tcs with a similar intensity of typhoon bopha moreover there are no boulder deposits at the shore which implies that the reef has not been affected by tsunamis even if one or more tsunamis have inundated the reef the associated hydraulic forces appear to have been lower than those of typhoon bopha these findings indicate that typhoon bopha has probably generated the most intense wave event in recent times however it is likely that tropical cyclones more intense than typhoon bopha will affect the reef in the near future as the climate continues to warm through the 21st century consequently the study site will probably face an increased risk of coastal erosion and destruction of property if no plans are developed to reduce and manage such impacts

a review of aridity and groundwater surface hydrological studies are seen as inadequate in hyperarid and arid areas to provide reliable estimates of recharge in most such areas surface discharges are not present so that assessments of groundwater resources are dependent upon ground interpretation and denied the flow control found in assessments elsewhere groundwater models show that gradients are sustained by long term dewatering and very small amounts of modern indirect recharge recharge indications are well within the error of a hydrological balance discharges appear equally small the development of groundwater in arid areas frequently faces problems of salination due to recycling of irrigation water and rising groundwater heads abstraction is often inadequately managed so that uncontrolled mining of groundwater occurs the advantage that groundwater has however is that it offers staged development and staged appraisal

salt crust development in paddy fields owing to soil evaporation and drainage contribution of chloride and deuterium profile analysis summary in northeast thailand lowlands with shallow saline watertable rainfed paddy fields often present high salt concentration in the dry season forming patches or spots of salt crusts on the soil surface in this context the mechanisms implied in salt concentration during dry season were studied by establishing salt budget with evaporation and drainage estimates inside and outside a saline patch drainage was estimated by hydrus 1d modelling constrained by an hydrodynamic characterization and the profile of water contents at the end of dry season evaporation rates at the end of the dry season were computed by interpreting natural detailed profiles of deuterium d and chloride cl contents because of the drastic diminution of hydraulic conductivity at saturation with depth and the decrease of groundwater level at the end of the cropping season simulated hydrological balance with hydrus 1d pointed out zero cumulated fluxes for depths of 39 5 cm outside the saline patch and 37 5 cm inside the saline patch therefore all the chloride accumulated in the very upper layers during dry season comes from the chloride that was present in the 0 39 5 cm layers before the beginning of the drying inside the saline patch the tentative cl budget is coherent with the hypothesis of saturation of the profile by aquifer saline water during the flooding evaporation rates computed from the diffusion of chloride and deuterium at the end of the drying season when the aquifer level was 1 4 m deep range between 0 121 and 0 378 mm d 1 this does not sustain the assumption of a considerable salinity contribution from the aquifer during the dry season moreover evaporation estimates based on cl and d diffusion equilibrium showed depleted rates 38 63 inside the saline patch due to salt accumulation in the first 12 cm of the soil in the vapour transfer layer estimated evaporation rate based on the vapour movement of d was in the same order of magnitude than computed rate assuming liquid cl diffusion this coincidence is attributed to the liquid fluxes that occurred during the expansion of the vapour transfer layer during the progression of the evaporation front

were extreme waves in the rockall trough the largest ever recorded 1 in february 2000 those onboard a british oceanographic research vessel near rockall west of scotland experienced the largest waves ever recorded by scientific instruments in the open ocean under severe gale force conditions with wind speeds averaging 21 ms 1 a shipborne wave recorder measured individual waves up to 29 1 m from crest to trough and a maximum significant wave height of 18 5 m the fully formed sea developed in unusual conditions as westerly winds blew across the north atlantic for two days during which time a frontal system propagated at a speed close to the group velocity of the peak waves the measurements are compared to a wave hindcast aes40 swail and cox 2000 which successfully simulated the arrival of the wave group but underestimated the most extreme waves

multiple dating approach 14c 230th u and 36cl of tsunami transported reef top boulders on bonaire leeward antilles current achievements and challenges abstract dating the transport deposition time of supratidal coarse clast deposits is difficult limiting their value for inferring frequency magnitude patterns of high energy wave events on bonaire leeward antilles caribbean these deposits form prominent landforms and transport by one or several holocene tsunamis is assumed at least for the largest clasts although a large dataset of 14c and electron spin resonance esr ages is available for major coral rubble ridges and ramparts it is still debated whether these data reflect the timing of major events and how these datasets are biased by the reworking of coral fragments as an attempt to overcome the current challenges for dating the dislocation of singular boulders three distinct dating methods are implemented and compared i 14c dating of boring bivalves attached to the boulders ii 230th u dating of post depositional secondary calcite flowstone and subaerial microbialites at the underside of the boulders and iii surface exposure dating of overturned boulders via 36cl concentration measurements in corals approaches ii and iii have never been applied to coastal boulder deposits so far the three 14c age estimates are older than 40 ka i e most probably beyond the applicability of the method which is attributed to post depositional diagenetic processes shedding doubt on the usefulness of this method in the local context the remarkably convergent 230th u ages all pointing to the late holocene period 1 0 1 6 ka are minimum ages for the transport event s the microbialite sample yields an age of 1 23 0 23 ka and both flowstone samples are in stratigraphic order the older onset of carbonate precipitation and younger flowstone layers yield ages of 1 59 0 03 and 1 23 0 03 ka respectively four coral samples collected from the topside of overturned boulders yielded similar 36cl concentration measurements however the computed ages are affected by large uncertainties mostly due to the high natural chlorine concentration after correction for the inherited component and chemical denudation since platform emergence inducing additional uncertainty the calculated 36cl ages cluster between 2 5 1 3 and 3 0 1 4 ka for three of four boulders whilst the fourth one yields an age of 6 1 1 8 ka probably related to a higher inheritance these 230th u and 36cl age estimates are coherent with a suggested tsunami age of

evaporation and land surface energy budget at the salar de atacama northern chile playa systems are driven by evaporation processes yet the mechanisms by which evaporation occurs through playa salt crusts are still poorly understood in this study we examine playa evaporation as it relates to land surface energy fluxes salt crust characteristics groundwater and climate at the salar de atacama a 3000 km 2 playa in northern chile containing a uniquely broad range of salt crust types land surface energy budget measurements were taken at eight representative sites on this playa during winter august 2001 and summer january 2002 seasons measured values of net all wave radiation were highest at vegetated and rough halite crust sites and lowest over smooth highly reflective salt crusts over most of the salar de atacama net radiation was dissipated by means of soil and sensible heat fluxes dry salt crusts tended to heat and cool very quickly whereas soil heating and cooling occurred more gradually at wetter vegetated sites sensible heating was strongly linked to wind patterns with highest sensible heat fluxes occurring on summer days with strong afternoon winds very little energy available at the land surface was used to evaporate water eddy covariance measurements could only constrain evaporation rates to within 0 1 mm d k1 and some measured evaporation rates were less than this margin of uncertainty evaporation rates ranged from 0 1 to 1 1 mm d k1 in smooth salt crusts around the margin of the salar and from 0 4 to 2 8 mm d k1 in vegetated areas no evaporation was detected from the rugged halite salt crust that covers the interior of the salar though the depth to groundwater is less than 1 m in this area these crusts therefore represent a previously unrecorded end member condition in which the salt crusts form a practically impermeable barrier to evaporation q 2005 elsevier b v all rights reserved

palaeohurricane reconstructions from sedimentary archives along the gulf of mexico caribbean sea and western north atlantic ocean margins hurricanes annually threaten the atlantic ocean margins historical hurricane records are relatively short and palaeohurricane sedimentary archives provide a geological and climatic context that sheds light on future hurricane activity here we review palaeo trends in hurricane activity elucidated from sedimentary archives we discuss dating methods site selection and stat istics associated with previously published records these archives have been useful for under standing the long term evolution of coastal systems and the response of intense hurricane activity to climatic changes regional shifts in hurricane overwash on centennial to millennial timescales have been linked to various climatic modes of variability including el nino southern oscillation and the north atlantic oscillation but could also reflect regional scale controls on hurricane activity

distinguishing tsunami and storm deposits an example from martinhal sw portugal abstract geological identification of past tsunamis is important for risk assessment studies especially in areas where the historical record is limited or absent the main problem when using the geological evidence is to distinguish between tsunami and storm deposits both are high energy events that may leave marine traces in coastal stratigraphic sequences at martinhal sw portugal both storm surge and tsunami deposits are present at the same site within a single stratigraphic sequence which makes it suitable to study the differences between them excluding variations caused by local factors the tsunami associated with the lisbon earthquake of november 1st 1755 ad had a major impact on the geomorphology and sedimentology of martinhal it breached the barrier and laid down an extensive sheet of sand as described in eyewitness reports besides the tsunami deposit the stratigraphy of martinhal also displays evidence for storm surges that have breached and overtopped the barrier flooding the lowland and leaving sand layers both marine derived flood deposits show similar grain size characteristics and distinctive marine foraminifera the most important differences are the rip up clasts and boulders exclusively found in the tsunami deposit and the landward extent of the tsunami deposit that everywhere exceeds that of the storm deposits identification of both depositional units was only possible using a collection of different data and extensive stratigraphical information from cores as well as trenches

three dimensional modeling of coastal boulders using multi view image measurements coarse clastic sediments boulders on coastlines have seen a groundswell in geomorphic research interest over recent years associated in part with the potential of boulder evidence for interpreting characteristics of high energy wave processes yet the fundamental property of boulder volume is normally difficult to measure accurately owing to complex clast morphology and irregular surface texture to tackle this problem this paper concentrates on creating precise measurable and textured three dimensional 3d models of coastal boulders without physical contact with the object based on multi view image measurement techniques this method has several advantages over traditional measurements that are inaccurate or alternative solutions using costly techniques such as terrestrial laser scanning our methods propose the use of low cost equipment digital cameras that can be used in various coastal environments to easily acquire numerous images of the object of interest initial results can be rapidly assessed in the field for immediate quality control resulting 3d models built from overlapping multi view digital photographs allow the reconstruction of realistic looking and textured boulder surfaces a particular interest in this task is the family of algorithms known as structure from motion sfm the work presents analysis of sfm techniques by examining 3d models of boulders observed at a coastal field site on lu dao island in south eastern taiwan copyright 2013 john wiley sons ltd

boulder ridges on the aran islands ireland recent movements caused by storm waves not tsunamis abstractireland s aran islands are an excellent place to test whether coastal boulder deposits including individual rocks weighing several tens of tonnes near sea level and clasts weighing several tonnes transported at tens of meters above sea level require a tsunami for emplacement or whether storm waves can do this work elongate deposits of cobbles boulders and megagravel are strung along the atlantic coasts of the aran islands no tsunamis have affected this region in recent centuries so if these deposits are forming or migrating at the present time they must be storm activated we find a diverse range of evidence for recent ridge activity first shells of hiatella arctica subtidal rock boring bivalves preserved in life position within ridge boulders yield radiocarbon ages from 200 ad to modern post 1950 ad second recent motion is attested to by eyewitness accounts that pin the movement of several individual 40 80 t blocks to a specific 1991 storm and by repeat photography over the last fe

advantages of beachrock slabs for interpreting high energy wave transport evidence from ludao island in south eastern taiwan abstract powerful typhoons frequently affect eastern taiwan on dabaisha beach on the sw coast of ludao island a small volcanic island lying se off mainland taiwan the presence of numerous beachrock slabs provides evidence of the sediment transport capabilities of high energy waves generated by these storms with a well defined beachrock source from which the slabs were derived it is easy to differentiate clasts transported in run up or backwash flow based on their current position relative to the outcrop in order to estimate the wave generated flow velocities from the measured beachrock slabs the hydrodynamic equations for boulder transport by nandasena et al 2011 have been rearranged so that they are appropriate for this particular geomorphic setting where exposed in situ beachrock outcrops liberate clasts which may then be transported either by run up onto the beach or backwash flow onto adjacent reef platforms such settings are common on tropical coastlines with fringing coral reefs and beaches comprising mostly biogenic sediments in the dabaisha beach case the lowest flow velocities required to transport all measured beachrock slabs from their source outcrop to current positions are 2 18 3 16 m s for run up and 1 76 3 24 m s for backwash with a discussion of advantages and limitations on the use of beachrock clasts for interpreting wave behaviour this paper presents another proxy for studying high energy wave events that is highly suitable for certain carbonate rich coastlines

waves coastal boulder deposits and the importance of the pre transport setting the pre transport environment of a coastal boulder along with its shape size and density determines the height of wave required for it to be transported different forces act on sub aerial boulders as opposed to submerged boulders when struck by a wave boulders derived from joint bounded blocks on shore platforms predominantly experience lift force and require a wave of greater height to be transported than boulders in other environments no one equation is applicable to determine the height of palaeo waves responsible for depositing a field or ridge of imbricated coastal boulders a range of equations and their derivation is presented here which can be applied to the respective pre transport environment of a boulder such an approach is necessary when attempting to reconstruct the frequency and magnitude of past coastal wave hazards and for differentiating between tsunami and storm wave deposited boulder fields

potential and limits of combining studies of coarse and fine grained sediments for the coastal event history of a caribbean carbonate environment the coastal deposits of bonaire leeward antilles are among the most studied archives for extreme wave events ewes in the caribbean here we present more than 400 electron spin resonance esr and radiocarbon data on coarse clast deposits from bonaire s eastern and western coasts the chronological data are compared to the occurrence and age of fine grained extremewave deposits detected in lagoons and floodplains both approaches are aimed at the identification of ewes the differentiation between extraordinary storms and tsunamis improving reconstructions of the coastal evolution and establishing a geochronological framework for the events although the combination of different methods and archives contributes to a better understanding of the interplay of coastal and archive related processes insufficient separation superimposition or burying of coarse clast deposits and restricted dating accuracy limit the use of both fine grained and coarse clast geoarchives to unravel decadal to centennial scale events at several locations distinct landforms are attributed to different coastal flooding events interpreted to be of tsunamigenic origin coastal landforms on the western coast have significantly been influenced by sub recent hurricanes indicating that formation of the coarse clast deposits on the eastern coast is likely to be related to past events of higher energy

emplacement and movement of boulders by known storm waves field evidence from the okinawa islands japan abstract field observations from previous studies of boulder movements were compiled to augment our own work on boulders that have been displaced by storm waves during recent typhoon events in the okinawa islands japan to elucidate the ability of storm waves to move boulders our observations reveal that recent storm waves displaced by sliding and overturning 100 ton boulders emplacing them on the reef or high cliff tops and that storm waves might also be capable of displacing 200 ton boulders on the reef the weights of storm wave boulders at the okinawa islands are of comparable order to those boulders displaced by historical tsunami origins consequently boulder weight alone is an inappropriate parameter to discriminate between tsunami or storm wave processes however these heavy storm wave boulders are close to the reef and cliff edges while tsunami boulders can be deposited much further inland hence horizontal displacement distance of boulders could be a useful parameter to discriminate boulders deposited by the tsunami and storm waves on the wide fringing reef the storm wave boulders were characteristically concentrated on the southeastern pacific ocean sides of each island but large boulders are rarely found on the northwestern east china sea side this is probably because the storm wave intensities are generally stronger at the southeastern side than at the northwestern side although differences of reef strength and initial condition of boulders should also be taken into account consideration of the high frequency of typhoons at the area suggests that effects of the storm waves and the consequent displacement of boulders on the reef might have contributed to the formation of the reef moat framework that typifies the okinawa islands especially if the moat is located within the transport limit of the storm wave boulders approximately 300 m from the reef edge at the islands

boulder transport by the 2011 great east japan tsunami comprehensive field observations and whither model predictions abstract predicting the local size of a historic high energy event from its boulders using numerical models is a challenging research topic modern high energy events and their deposits are useful to validate these models however validating the accuracy of the results is difficult due to the scarcity of good datasets or the ambiguity of existing field data data on boulders transported by the 2011 great east japan tsunami at coastal sites settai taro and karakuwa on the northeast coast of japan were compiled pre tsunami locations and settings and transport distances were found from evidence such as photographs aerial images and the testimony of survivors the estimated weight of the boulders analyzed ranged from 11 to as much as 167 t while the transport distance varied from a few to up to 600 m modeling results predicted that the minimum limit of maximum flow velocity of the tsunami at the pre tsunami locations of the boulders varied from 4 2 to 6 8 m s the measured maximum flow depths at settai 17 18 m and taro 14 m were within the predicted range of flow depth when the froude number 1 0 1 5 numerical model estimates for an older boulder 285 t in settai indicate that it was probably transported by a historical tsunami 1611 keicho sanriku event which may have been similar to or bigger than that of the 2011 event in the area the maximum flow velocity could not have been less than 6 1 m s and if the boulder was transported to the present location by rolling the flow velocity must have been within 7 5 23 7 m s following systematic validation the numerical modeling of boulder transport is proving promising for reconstructing the local magnitude of historical high energy events further improvements can be made with additional high quality field data from modern high energy events

the late quarternary salinity record of lake frome south australia evidence from na in stratigraphically preserved gypsum abstract traces of foreign ions are incorporated into the structure of gypsum during precipitation the amount of foreign material included in the crystal is dependent on its concentration in the precipitating solution and therefore the trace element composition of the gypsum can be related to the composition of brines from which it precipitated a late quaternary salinity record for lake frome south australia derived from the analysis of na in gypsum is consistent with much of the previously inferred climatic history of southeast australia the record indicates three periods of lake filling at 17 000 yr b p from 15 000 to 13 500 yr b p and from 13 000 to 11 000 yr b p lake frome was dry prior to 17 000 yr b p between 16 500 and 15 000 yr b p at 13 000 yr b p and between 6000 and 4000 yr b p

sedimentation et fracturation de haute energie en milieu recifal tsunamis ouragans et cyclones et leurs effets sur la sedimentologie et la geomorphologie d un atoll motu et hoa a rangiroa tuamotu pacifique se abstract a longitudinal festoon fracture of the reef flat widened by slow biological and mechanical erosion transverse along the grooves divides the nw coral rim of rangiroa tuamotu se pacific into colossal blocks 15 10 5 m 1500 t the elaboration of these blocks can be attributed to the dislocation of the top of the reef flat by catastrophic events tsunamis or hurricanes typhoons in the sw and s pacific the shifting of these blocks mega boulders would necessitate a considerable amount of energy and at present we cannot decide which one of these phenomena was responsible various examples observed in the pacific are cited to illustrate abrupt changes in the sea level these could be attributed either to meteorological events hurricanes cyclones or typhoons or to seismic events of very high energy ground sea or tsunamis the reader is reminded of the different characteristics that these phenomena produce this study is mainly concerned with tsunamis especially the frequency of their occurrence energy and effects on the coasts of small oceanic islands hurricanes cyclones and typhoons roughly originate from the n ne and e whereas tsunamis originate from all directions except from se s and sw angle these very high energy events hurricanes and tsunamis seem then to be responsible for 1 the decreasing grain size of the coral rim sediments from the ocean to the lagoon through the range of colossal blocks smaller boulders scree gravels coarse and fine sands 2 the sedimentary accretion of the motu itself at each very high energy so called catastrophic event they are also responsible for the preservation of the two characteristic geomorphic forms of an atoll motu and hoa 3 finally the alternation motu hoa motu etc on the coral rim this alternation seems to result from the interaction between oceanic disturbances hurricanes or tsunamis and the water volume which must flow over the coral rim the transported material the reef flat and the angle of incidence between the swell and the coast during these catastrophic events

modelling holocene relative sea level observations from the caribbean and south america abstract holocene data from the caribbean and the atlantic coast of south america have been critically assessed and a subset of the best quality data are presented these data cover a large north south geographic extent and display a distinct spatial variation we make the first comparisons of this data set to predictions based on a realistic model of glaciation induced sea level change with the main aims of understanding the cause of the observed spatial trend and estimating a eustatic signal for the holocene the spatial variation is dominated by the influence of the ice and ocean mass redistribution on sea level change with the ice induced effect dominating the observed north south trend a best fitting model is applied to estimate a holocene eustatic signal from the observations we find that the model corrected data are consistent with a relatively rapid rise of 7 8 mm yr in the early holocene with a marked reduction in this rate around 7 cal kyr bp from this time until present the model corrected data suggest that the volume of mass transfer between ice sheets and oceans was no more than 1 m eustatic sea level equivalent

distribution geomorphology and lithofacies of cliff top storm deposits examples from the high energy coasts of scotland and ireland abstract cliff top storm deposits ctsds occur on cliffs at elevations of up to 50 m above sea level at exposed sites on the deep water coasts of the british isles this study examines the distribution geomorphology and lithofacies of ctsds at sites from shetland orkney caithness and the outer hebrides in scotland and from the aran islands in galway bay in ireland ctsds are generated largely by the quarrying of blocks from the cliff top and transported by green water bores across cliff top platforms and ramps to be deposited in backing ridges or as debris spreads maximum boulder sizes reach 48 m 3 but it is likely that much larger blocks can be quarried prior to disintegration during transport eye witness accounts and field mapping demonstrate that formation and modification of ctsds has continued during major storms over recent decades recent ctsds bury a range of man made debris but older deposits lack this and instead show weathering effects that indicate a longer residence time in shetland osl dates on intercalated sands suggest that the oldest ctsds date from 800 ad radiocarbon dates on shell buried inside ctsd ridges relate to major storms between 1700 and 1900 ctsds represent an overlooked archive of storm sedimentation that has great potential for the elucidation of local storm chronologies ctsds also provide evidence of wave impacts on any part of the cliff face or top in fundamental contrast to the concentration of wave action at the cliff foot implicit in traditional models of the erosion of rock coasts

uncertainties around modelling of steady state phreatic evaporation with field soil profiles of δ18o and chloride summary the application of the general advection diffusion equation to model phreatic evaporation flux rates from solute concentration soil profiles has been applied to a variety of arid zone locations but the effects of heterogeneous and uncertain field data on modelling performance are rarely described we revisit and extend the model by accounting for the effects of variable water content and sediment type on the impedance factor and in turn effective diffusion coefficient we explore the local sensitivity of the extended model to its major assumptions and parameter values the mean diffusion coefficient of the soil profile data is most sensitive to the volumetric water content close to the evaporation front and so modelled evaporation results can be very sensitive to uncertainty around the position of the evaporation front the uncertainty in the position of the groundwater reservoir and its concentration has little effect where the lower part of the profile shows an asymptotic trend towards a representative value of groundwater concentration but can vary substantially with different values of groundwater depth and concentration if this is not the case field data from the southern margin of the great artesian basin are shown to exhibit considerable uncertainty around the boundary conditions of the advection diffusion model e g position of evaporation front depth and concentration of lower groundwater boundary condition resulting phreatic evaporation flux estimates show a wide range that needs to be considered when using these data in water balance studies of groundwater systems

the use of boulders for characterising past tsunamis lessons from the 2004 indian ocean and 2009 south pacific tsunamis tsunamis are high energy events capable of transporting extremely heavy loads including boulders we compare boulder deposits created by two modern tsunami events the 2004 indian ocean and the 2009 south pacific tsunamis where the boulder sources were in similar topographic settings and for which we have accurate data on the wave characteristics boulder distribution preferential orientation and numerical simulation of boulder transport are discussed a comparison between the impacts of the south pacific and indian ocean tsunamis shows similar characteristics such as limited landward extent and the absence of landward fining differences between the results from modelling and field data are most probably caused by variables such as coastal plain roughness buildings trees microtopography particle shape and boulder collision during transport that are summarised as coefficients in the mathematical models characterising modern events through coarse sediment deposits provides valuable information to help identify and interpret palaeo tsunami imprints on coastal landscapes

extraordinary boulder transport by storm waves west of ireland winter 2013 2014 and criteria for analysing coastal boulder deposits abstract before and after photos of supratidal coastal boulder deposits cbd in the west of ireland show that storms in the winter of 2013 2014 transported boulders at elevations up to 29 m above high water and at inland distances up to 222 m among the clasts transported are eighteen weighing more than 50 t six of which exceed 100 t the largest boulder moved during those storms weighs a fairly astonishing 620 t the boulders moved in these recent storms provide pinning points for mapping storm wave energies on coasts their topographic positions mark elevations and distances inland reached by wave energies sufficient to dislocate those specific masses taken together the cbd data reveal general relationships that shed light on storm wave hydrodynamics these include a robust correlation inverse exponential between maximum boulder mass transported and emplacement height above high water the greater the elevation the smaller the maximum boulder size with a dependency exponent of about 0 2 times the elevation in metres there is a similar relationship although with a much smaller rate of change exponent 0 02 between boulder mass and distance inland which holds from the shoreline in to about 120 m coastal steepness calculated as the ratio of elevation to inland distance seems to exert the strongest control with an inverse power law relationship between maximum boulder mass and slope ratio the more gentle the topography the larger the moved boulders quantifying cbd dynamics helps us understand the transmission of wave energies inshore during high energy storm events the transported boulders documented here are larger than many of those interpreted to have been moved by tsunami in other locations which means that boulder size alone cannot be used as a criterion for distinguishing between tsunami and storm emplacement of cbd the biggest blocks up to 620 t are new maxima for boulder mass transported by storm waves we predict however that this record will not last long the 2013 2014 storms were strong but not extreme and there are larger boulders in these deposits that didn t move on this occasion bigger storms will surely move larger clasts and clasts at greater distances from the shoreline these measurements and relationships emphasise the extreme power of storm waves impacting exposed coastlines and require us to rethink the upper limits of storm wave energy at coasts

catastrophic wave erosion bristol channel united kingdom impact of tsunami abstract on january 30 1607 a massive wave from the ocean surged up bristol channel in the united kingdom flooding more than 500 km2 of lowland along 570 km of coast it killed 2000 people and is considered britain s worst natural disaster on land the wave occurred on a fine day and surprised inhabitants contemporary descriptions of the event have many of the characteristics of accounts of recent catastrophic tsunamis geomorphic evidence for tsunamis in the channel can be found in the form of transported and imbricated boulders bedrock sculpturing on coastal platforms and ramps and at isolated locations wholesale erosion of the coastal landscape hydrodynamic calculation of the height of the tsunami and flow velocities can be derived from boulder dimensions tsunami wave height increased from 4 m in the outer bristol channel to more than 6 m within the inner severn estuary theorized flow velocities range between 11 8 and 18 1 m s 1 increasing up the estuary under topographic enhancement thes

sedimentary features of tsunami deposits in carbonate dominated beach environments a case study from the 25 october 2010 mentawai tsunami this study provides a case history of tsunami deposition in a carbonate dominated environmental setting we present the results of a sedimentological investigation conducted on deposits formed by the 25 october 2010 mentawai island tsunami and report on deposits analyzed at three sites on north pagai island sabeu gunggung macaroni resort and tumalei the deposits are mainly composed of medium to coarse sand sized fragments of corals shells and foraminifera with thickness ranging from 3 to 26 cm the deposits consist of two to five layers with fining upward trends dominating local topography noticeably affects the thickness number of layers and distribution of tsunami deposits the foraminiferal assemblage and diversity vary at each sample point along transect and between different transects based on the foraminiferal content most of the deposit material likely came from shallower depths in addition density distribution of the tsunami deposit material exhibits some degree of variability in terms of the range of densities in each sample and the trend of the overall density along each transect in contrast to heavy mineral dominated deposits the density of carbonate grains as a function of size may be an important consideration when carbonate dominated deposits are used to interpret hydraulic conditions that created a particular tsunami deposit since there are relatively few studies of tsunami deposits in carbonate dominated environmental settings such as the mentawai islands our study provides a useful case history of tsunami deposition in such an environmental setting

evidence of high energy events in the geological record mid holocene evolution of the southwestern donana national park sw spain abstract four phases are distinguished in the mid holocene evolution of the southwestern donana national park sw spain based on the multidisciplinary study of sediments in drill cores in the oldest phase 5500 5400 cal years bp a coastal brackish lagoon occupied the central part of the study area partly enclosed by the donana spit and limited by fluvial levees an evolution from subtidal to intertidal conditions characterized the areas located close to the inner side of the donana spit during the same phase the following phase 5400 5200 cal years bp is characterized by a high energy event tsunami which caused the breakthrough of the donana spit and the creation of new littoral strands in the inner areas in the first period of the third phase 5200 4200 cal years bp estuarine infilling was probably the dominant process with the accumulation of phyllosilicate rich clays in the lagoon bed this was followed by a renewed phase of instability 4200 4100 cal years bp indicated by the presence of fine storm lain deposits and thicker probably tsunami induced shelly deposits the last phase 4100 3700 cal years bp comprises a an infilling period with a diminution of the marine influence and b two new high energy events which caused the erosion of the donana spit and the creation of new cheniers in the last 7000 years the comparison of these results with a revision of both geological and historical records has revealed the occurrence of twenty tsunamis at least during this period in portugal and southern spain evidences of these high energy events are washover fans bioclastic coarse sized layers within salt marsh deposits or the presence of giant boulders and pebbles the determination of the recurrence period is very difficult owing to the very scarce data although our data and other authors do not discard a possible periodicity of 2000 years for a cycle of two events separated by 300 400 years

huge erratic boulders in tonga deposited by a prehistoric tsunami along some coastlines there are erratic boulders apparently emplaced by tsunamis or cyclonic storms evaluating their origin and time of emplacement places constraints on the frequency severity and location of coastal hazards seven such large coral limestone boulders are present near fahefa village on tongatapu island southwest pacific apparently emplaced by a prehistoric tsunami these boulders are 10 20 m above sea level and above any possible source and all are 100 400 m from the present shoreline coral 230th ages indicate that the limestone formed during the last interglacial sea level highstand ca 120 130 ka the largest boulder is 20 times more massive than any reported boulders emplaced by historically documented storms and may be the largest known tsunami or storm erratic worldwide situated above its source we performed computer simulations to assess whether tsunamis produced by earthquakes undersea landslides or volcanoes could emplace the boulders the simulations indicate that either volcanic flank collapse along the tofua arc 30 40 km to the southwest or undersea landslides on the submarine slopes of tongatapu could be responsible either could explain why these boulders are not widespread on tongatapu and instead occur in a localized group along the western coast this study demonstrates that small 1 km3 submarine slope failures sometimes generate locally large tsunamis the fahefa boulders are in a well studied and well populated area yet were unknown to the scientific community until recently this suggests that systematic searches elsewhere for erratic boulders and other tsunami deposits might provide new information for assessing the size and extent of prehistoric tsunamis

reassessment of hydrodynamic equations minimum flow velocity to initiate boulder transport by high energy events storms tsunamis abstract coastal boulders are good evidence of high energy events but the distinction between storm and tsunami boulders remains difficult to identify and mathematical models are still in their preliminary stages in a pioneering contribution nott 1997 2003 developed hydrodynamic equations to assess the minimum wave height required to initiate transport of a coastal boulder by tsunamis or storm surges these equations are widely cited and used but they can be improved in this study nott s equations have been revised 1 the equation for the submerged boulder scenario has been revised by rearranging the lift area of the lift force 2 the subaerial boulder scenario has been reconsidered by rearranging lift area and omitting inappropriate use of inertia force and 3 the joint bounded scenario was revised by balancing force components in the lifting direction and the effect of slope at the pre transport location is tested calculations are performed for four case studies boulders in western and eastern australia data after nott 1997 2003 boulders in southeastern italy data after scicchitano et al 2007 storm boulders in iceland data after etienne and paris 2010 and 2004 tsunami boulders in sumatra data after paris et al 2009 the minimum flow velocity required to initiate the transport of submerged boulders in the revised equation is less than that in nott s equation e g reductions up to 56 for submerged boulders and 65 for joint bounded blocks the minimum flow velocity required to initiate the transport of subaerial boulders from the revised equation also differed in comparison with nott s equation e g 4 22 for boulders detached from a seawall by the 2004 tsunami in sumatra while nott s equation was not applicable to some boulders e g beach rock boulders transported from the nearshore by the 2004 tsunami if we consider a joint bounded scenario for storm boulders in iceland the minimum flow velocity differs 43 to 41 from the results from nott s equation a boulder transport histogram is then introduced to represent the range of flow velocity that satisfies the requirements for initial transport of a boulder in different modes sliding rolling and saltation the boulder transport histogram can be used to predict the possible initial transport mode of a boulder from the flow velocity these theoretical results are compared to field data thus suggesting the initial transport mode of boulders and their pre transport locations the boulder transport histogram would be a valuable tool to reconstruct the magnitude of prehistoric high energy events such as tsunamis or storm surges in terms of flow velocity

an extreme wave event in eastern yucatan mexico evidence of a palaeotsunami event during the mayan times the yucatan peninsula mexico has typically been considered a tectonically stable region without significant seismic activity in contrast the region is one that is regularly affected by hurricanes a detailed survey of ca 100 km of the eastern yucatan and cozumel coast identified the presence of ridges containing boulders measuring 1 m with up to three ridges at some locations the ridges reach five metres in height and their origin is associated with extreme wave event ewe activity previously modelled tsunami waves from known seismically active zones in the region muertos thrust belt and south caribbean deformed belt are not of sufficient at the yucatan peninsula to have produced the boulder ridges recorded in this study the occurrence of hurricanes in this region is more common but two of the most destructive hurricane gilbert 1988 and hurricane wilma 2005 produced coastal waves too small to have created the ridges recorded here in this paper a new tsunami model has been generated that indicates a tsunami event may have caused the ewe that resulted in the deposition of the boulders ridges

cl br ratios and environmental isotopes as indicators of recharge variability and groundwater flow an example from the southeast murray basin australia abstract systematic variations in cl br ratios together with r 36 cl values 14 c activities and 18 o values reflect differences in groundwater recharge and define groundwater flow paths in the riverine province of the southeast murray basin in groundwater from the shallowest shepparton formation homogenisation of cl br and 18 o values and a decline in 14 c activities with depth imply that vertical flow dominates the 14 c activities define variations in pre land clearing recharge in the palaeovalleys of present day rivers deep leads which contain sandier sediments higher recharge 0 5 to 1 4 mm year produced relatively fresh groundwater tds 36 cl values in groundwater from the goulburn subcatchment zones of groundwater with variable cl br ratios in the deeper calivil renmark aquifer also allow the detection of rapid leakage from the surface that has the potential to compromise groundwater resources

extreme waves under hurricane ivan hurricane ivan a category 4 storm passed directly over six wave tide gauges deployed by the naval research laboratory on the outer continental shelf in the northeastern gulf of mexico waves were observed with significant wave heights reaching 17 9 meters and maximum crest to trough individual wave heights of 27 7 meters 91 feet analysis suggests that significant wave heights likely surpassed 21 meters 69 feet and that maximum crest to trough individual wave heights exceeded 40 meters 132 feet near the eyewall

boulder accumulations related to storms on the south coast of the reykjanes peninsula iceland coastal boulder accumulations are often mentioned in the literature even though their interpretation remains difficult especially along rock coasts affected both by storms and tsunamis studies on the geomorphic impact of such high energy events are actually of great interest since their intensity and frequency are key issues for the future evolution of coasts in the framework of the global change the southwest coast of iceland faces the powerful storms of the north atlantic ocean with wave heights of more than 15 m the probability for past and present tsunamis to hit this coast is very low in this paper we describe boulder accumulations along the volcanic rock coast of reykjanes southwest iceland they consist of cliff top boulders clusters and ridges beaches and boulder fields large boulders up to 70 t in weight have been transported and deposited up to 65 m inland 6 masl the maximum limit of boulder deposition and driftwood was found respectively 210 m and 550 m inland storms appear to be a predominant factor in the geomorphic evolution of reykjanes coasts our observations also give new insight for the interpretation of coastal boulder accumulations processes of erosion and deposition by tsunamis are a rising topic in the literature and the effects of recurrent and powerful storms are neglected

evidence for a mesoscale thermal circulation over dry salt lakes abstract because of albedo and thermal conductivity effects dry salt lakes in central australia exhibit a characteristics thermal signature within the overall landscape having much cooler daytime surface temperatures and warmer nocturnal temperatures than the surrounding environment various aspects of a possible mesoscale thermal circulation arising from such a thermal differentiation have been investigated for the salt lake a moderately sized 70 km 2 dry salt lake in northwestern new south wales 30 05 s 142 08 e surface temperatures across the salt lake and surrounding landscape determined by field and polar orbiting noaa 9 satellite observations show marked variation with the salt crust remaining up to 16 k cooler than the surrounding sand country during the day and up to 8 k warmer at night that this thermal forcing can provide a horizontal pressure gradient sufficiently strong to induce air motion is confirmed by analysis of hourly output from a network of anemographs which were established around the perimeter of the salt lake during a five month autumn and winter period an extremely regular pattern of nocturnal near surface convergence lake warm and daytime divergence lake cool is shown a pattern which is enhanced when data are stratified for anticyclonic conditions with a weak pressure gradient 24 of total observations wind roses produced for a number of sites around the lake show a distinct diurnal reversal in near surface airflow with generally onshore flow by day and offshore flow at night confirmation that a diurnally reversing thermal circulation does operate under certain conditions at the salt lake is provided by pilot balloon analysis of winds aloft and by preliminary mesoscale modelling of airflow this circulation which has not previously been described in the literature may have important environmental and climatic implications in the australian context

size distribution of submarine landslides and its implication to tsunami hazard in puerto rico 1 we have established for the first time a size frequency distribution for carbonate submarine slope failures using detailed bathymetry along the northern edge of the carbonate platform north of puerto rico we show that the cumulative distribution of slope failure volumes follows a power law distribution the power law exponent of this distribution is similar to those for rock falls on land commensurate with their interpreted failure mode the carbonate volume distribution and its associated volume area relationship are significantly different from those for clay rich debris lobes in the storegga slide norway coupling this relationship with tsunami simulations allows an estimate of the maximum tsunami runup and the maximum number of potentially damaging tsunamis from landslides to the north shore of puerto rico

assessing the suitability of holocene environments along the central belize coast central america for the reconstruction of hurricane records since the belize coast was repeatedly affected by hurricanes and the paleohurricane record for this region is poor sediment cores from coastal lagoon environments along the central belize coast have been examined in order to identify storm deposits the paleohurricane record presented in this study spans the past 8000 years and exhibits three periods with increased evidences of hurricane strikes occurring at 6000 4900 4200 3600 and 2200 1500 cal yr bp two earlier events around 7100 and 7900 cal yr bp and more recent events around 180 cal yr bp and during modern times have been detected sand layers redeposited corals and lagoon shell concentrations have been used as proxies for storm deposition additionally hiatuses and reversed ages may indicate storm influence while sand layers and corals represent overwash deposits the lagoon shell concentrations which mainly comprise the bivalve anomalocardia cuneimeris and cerithid gastropods have been deposited due to changes in lagoon salinity during and after storm landfalls comparison with other studies reveals similarities with one record from belize but hardly any matches with other published records the potential for paleotempestology reconstructions of the barrier lagoon complexes along the central belize coast differs depending on geomorphology and deposition of washovers in the lagoon basins is limited probably due to the interplay of biological geological and geomorphological processes

evaporation rate from a salt pan estimates from chemical profiles in near surface groundwaters evaporation of water from saturated saline soils or sediments induces gradients of the solutes in the remaining interstitial solution these gradients lead to a systematic and predictable solute distribution in the soil solution which may be used in some cases to estimate the rate of evaporation simple one dimensional transport models for the distribution of cl and br indicate net evaporation rates from the salt covered surface of lake eyre south australia of between 0 9 and 2 8 cm yr 1 the former is a minimum estimate averaged over 20 yrs which includes the major 1974 filling event while the latter reflects the most recent summer evaporation period

understanding the history of extreme wave events in the tuamotu archipelago of french polynesia from large carbonate boulders on makemo atoll with implications for future threats in the central south pacific abstract numerous large carbonate boulders up to 164 tonnes in mass were investigated on the reef flat and beaches of makemo atoll in the tuamotu archipelago of french polynesia to reveal the past occurrence and to anticipate the future potential threat of extreme wave events possibly generated by tropical cyclones and tsunamis the modern reef edge and emerged mid holocene coastal landforms were identified as sources of boulders mobilized during extreme wave events in the past the minimum flow velocities produced by extreme wave events were estimated to exceed 5 4 15 7 m s at the reef edge on different parts of the atoll comparison of uranium thorium ages of boulder coral fabric with written historical records indicates that two large boulders 77 and 68 tonnes were possibly emplaced on the reef flat by a powerful cyclone in february 1878 although most boulder dates are older than the earliest historical cyclone and tsunami records in french polynesia their ages concur with the following a periods of storminess i e increased cyclone activity compared to today in the central south pacific over the last millennium and b periods of high sea surface temperature sst at the great barrier reef possibly associated with higher than normal ssts pacific wide that facilitated the generation of cyclones affecting the central south pacific ocean none of the boulders on makemo were dated younger than ce1900 implying that the last century has not experienced extreme waves of similar magnitude in the past nevertheless the findings suggest that waves of comparable magnitudes to those that have transported large boulders on makemo may recur in the tuamotus and threaten island coasts across the central south pacific in the future