the largest local tsunami in 20th century hawaii abstract the 1975 kalapana tsunami had waves that ran up to 14 6 m high it deposited a discontinuous basalt boulder and carbonate sand veneer on the halape apua point coast of the island of hawaii these deposits fine up to 320 m inland and 10 4 masl the deposit is an unusual sedimentary association in which sand sized material is a minor component both boulders and sand fine inland over the same distance not in a continuum and they terminate at approximately the same point boulders were transported and deposited by only one wave the second whereas the sand deposit was in part reworked by subsequent smaller waves boulder transport by one wave in association with a relative paucity of finer sediment reduced internal clast interference and helped to impart a marked fining inland sequence this fining inland sequence is at odds with work that proposes a chaotic or random nature of boulder emplacement by tsunamis where there is abundant sediment clast interference during entrainment will impede the fining inland of larger material in cases where it is difficult to determine the nature of inundation or the number of tsunamis a chaotic pattern may simply reflect deposition by storm tsunami or a combination of the two

modelling the processes of cliff top erosion and deposition under extreme storm waves at exposed sites on the deep water coasts of the british isles cliff top storm deposits ctsds occur on cliffs at a variety of elevations above sea level and may occasionally reach up to 50 m above sea level time series field mapping of ctsds has demonstrated their formation over the historical period and their continued modification during major past storms this paper seeks to clarify the morphogenetic context of ctsds model the wave conditions and forces encountered at the cliff face and cliff top platform and propose mechanisms to link wave processes to cliff face quarrying and landwards cliff top transport of quarried blocks to deposition zones at the rear of the cliff top platform we report on wave tank experiments using scaled cliff and wave conditions from a cliff in the shetland islands to focus on three situations incident waves lower than the cliff edge height at the same height as the cliff edge height and higher than the cliff edge height the modelling suggests that steep waves of 10 m and above impacting on a 15 m high cliff will result in impact pressures sufficient to promote crack propagation block detachment and lifting of large blocks large but not necessarily steep waves of the same height as the cliff edge produce sufficient impact pressures and water flow over the cliff edge and platform to entrain blocks transport and deposit them on the cliff top where cliff top height is below wave crest elevation green water bore flow occurs sufficient to force rotation or lifting of blocks out of cliff top and cliff top platform sockets high flow velocities rapidly accelerate and transport blocks inland until the flow attenuation results in deposition of blocks at the limit of run up the model results provide a good explanatory framework to account for the quarrying of the upper part of the cliff face and cliff top platform under storm wave conditions and provide an insight into the exceptional velocities experienced over the cliff top platform under bore flow conditions the modelling results show that extreme storm waves are capable of quarrying transporting and depositing large blocks at altitude and significant distances inland and so present serious questions about the use of such deposits as diagnostic of palaeo tsunami

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

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

tsunami deposits on the coastline of west crete greece abstract the eastern mediterranean and the aegean sea in particular are the most active seismic regions in europe historically numerous earthquakes have occurred in this part of the world and comprehensive tsunami recordings exist nevertheless field evidence of tsunamis is rare although many neotectonic movements certainly must have triggered very strong tsunami waves along the coastlines of western crete we found evidence for tsunami impacts such as 1 bimodal deposits large clasts floating in sands comprised of shell fragments 2 dislocation of large boulders with tilting of biogenous notches and 3 boulders with lithophaga or cliona borings weighing up to 75 tons thrown onshore and imbedded in strata of marine shells this paper documents these deposits and discusses whether they originated from the sudden uplift that occurred in 365 ad moreover numerical radiocarbon ages reveal the occurrence of two tsunamis dated to 5660 yrs bp and 500 yrs bp evidence for other tsunami impacts is discussed but not supported by numerical dating due to the lack of suitable material

distribution origin and transport process of boulders deposited by the 2004 indian ocean tsunami at pakarang cape thailand abstract the tsunami of 2004 in the indian ocean transported thousands of meters long boulders shoreward at pakarang cape thailand we investigated size position and long axis orientation of 467 boulders at the cape most of boulders found at the cape are well rounded ellipsoid in shape without sharp broken edges they were fragments of reef rocks and their sizes were estimated to be 3 22 7t the distribution pattern and orientation of long axis of boulders reflect the inundation pattern and behavior of the tsunami waves it was found that there is no clear evidence indicating monotonous fine coarse shoreward trends of these boulders along each transect line on the other hand the large boulders were deposited repeatedly along the three arcuate lines at the intertidal zone with a spacing of approximately 136m interval this distribution pattern may suggest that long lasting oscillatory flows might have repositioned the boulders and separated the big ones from small no boulders were found on land indicating that the hydraulic force of the tsunami wave rapidly dissipated on reaching the land due to the higher bottom friction and the presence of a steep slope we further conducted numerical calculation of tsunami inundation at pakarang cape according to the calculation the sea receded and the major part of the tidal bench area with boulders at present was exposed above the sea surface before the arrival of the first tsunami wave the first tsunami wave arrived at the cape from west to east at approximately 130min after the tsunami generation and then inundated inlands our calculation shows that tsunami wave was focused around the offshore by a small cove at the reef edge and spread afterwards in a fan like shape on the tidal bench the critical wave velocities necessary to move the largest and average size boulders by sliding can be estimated to be approximately 3 2 and 2 0m s respectively the numerical result indicates that the maximum current velocity of the first tsunami wave was estimated to be from 8 to 15m s between the reef edge and approximately 500m further offshore this range is large enough for moving even the largest boulder shoreward these suggest that the tsunami waves that were directed eastward struck the reef rocks and coral colonies originally located on the shallow sea bottom near the reef edge and detached and transported the boulders shoreward

geomorphological control on boulder transport and coastal erosion before during and after an extreme extra tropical cyclone extreme wave events in coastal zones are principal drivers of geomorphic change evidence of boulder entrainment and erosional impact during storms is increasing however there is currently poor time coupling between pre and post storm measurements of coastal boulder deposits importantly there are no data reporting shore platform erosion boulder entrainment and or boulder transport during storm events rock coast dynamics during storm events are currently unexplored here we use high resolution daily field data to measure and characterize coastal boulder transport before during and after the extreme northeast atlantic extra tropical cyclone johanna in march 2008 forty eight limestone fine medium boulders n 46 and coarse cobbles n 2 were tracked daily over a 0 1 km2 intertidal area during this multi day storm boulders were repeatedly entrained transported and deposited and in some cases broken down n 1 or quarried n 3 during the most intense days of the storm eighty one percent n 39 of boulders were located at both the start and end of the storm of these 92 were entrained where entrainment patterns were closely aligned to wave parameters these data firmly demonstrate rock coasts are dynamic and vulnerable under storm conditions no statistically significant relationship was found between boulder size mass and net transport distance graphical analyses suggest that boulder size limits the maximum longshore transport distance but that for the majority of boulders lying under this threshold other factors influence transport distance paired analysis of 20 similar sized and shaped boulders in different morphogenic zones demonstrates that geomorphological control affects entrainment and transport distance where net transport distances were up to 39 times less where geomorphological control was greatest these results have important implications for understanding and for accurately measuring and modelling boulder entrainment and transport coastal managers require these data for assessing erosion risk 2016 the authors earth surface processes and landforms published by john wiley sons ltd

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

shape evolution and fabric in a boulder beach monument cove maine abstract unequal spacing of nearly vertical joints and sheeting in hornblende granite at monument cove maine forms large tabular blocks which accumulate as talus on the backbeach the blocks are subsequently rounded by wave action to form a pocket boulder and cobble beach measurements of the talus blocks and boulders indicate that the initial structurally controlled bladed and elongate habits are manifested in the boulders however as abrasion progresses more compact spherical and more platy discoidal boulders evolve the data suggest that the greatest change is toward compactness and that the ultimate clast shape at monument cove would be spherical the orientations of the l i planes and the l axes of the rounded clases were also measured the l i planes are well oriented dipping m inly offshore the l axes orientations form three main clusters one subparallel to the shoreline one down the dip of the beach and one oblique to the shoreline the latter two clusters lie within the modal dip of the l i planes

sedimentology of rocky shorelines 4 coarse gravel lithofacies molluscan biofacies and the stratigraphic and eustatic records in the type area of the pleistocene hulopoe gravel lanai hawaii abstract during the pleistocene the south flank of lanai was the site of repeated erosion and deposition as a consequence of glacio eustasy superimposed on tectono isostasy throughout this time terrigenous and bioclastic gravel was generated along mainly rocky shorelines gravelly sediment was deposited in topographically low areas of the shoreface and inner shelf that later were uplifted isostatically the sedimentary lithofacies and biofacies in these deposits are distinctive but they represent a deposystem and suite of environments that hitherto have not been studied systematically these unrecognised circumstances have fuelled controversies about the nature and significance of the hulopoe gravel most notably the claim that it represents a mega tsunami deposit the hulopoe gravel in its type area displays a lithofacies succession that encompasses a complete disconformity bounded transgressive regressive cycle on a sand poor rocky shoreline this succession incorporates not only a distinctive vertical assemblage of rocky shoreline litho and biofacies but also internal disconformities that record episodes of erosion and non deposition during shoreline migration repetition of the lithofacies succession imparts overall stratigraphic order to the hulopoe gravel four unconformity bounded transgressive regressive cycles correspond to eustatic highstands of oxygen isotope stages 5 and 7 superimposed on continuing tectono isostatic uplift driven by growth of the island of hawaii this study of the hulopoe gravel demonstrates that the sedimentary record of mixed volcaniclastic carbonate depositional systems developed on rocky shorelines of tropical and subtropical oceanic island coasts can be preserved this record may include depositional products of both transgressive and regressive shorelines although tsunami and giant submarine landslides are known to occur in the hawaiian islands deposits and features that result from tsunami inundation above the shoreline such as might be expected from landslide related mega tsunami have not been recognised in the type area of the hulopoe gravel rocky palaeoshoreline records on oceanic volcanic islands may yield oceanographic and climatic clues that complement data obtained from other palaeoshoreline types

extended equilibrium beach profiles abstract the idea of an equilibrium beach profile has been a useful concept in both theoretical and practical coastal engineering studies in essence the subject has thus far evolved to a choice of shape functions which are described by a small set of parameters additional efforts have attempted to relate these parameters to more fundamental quantities such as average grain size of the bottom sediment wave environment geometric aspects of the beach and the like this approach has a long history and can rightly claim a certain level of success however the usual collections of shape functions are well known to have difficulties very near the shoreline let alone on the nearshore portion of the beach this study extends the equilibrium profile up to and somewhat past the shoreline three shape functions are used in conjunction with a taylor expansion for the nearshore and above water portions of the profile a nonlinear fitting technique is applied to estimate the model s best parameter values moreover reduced versions of the proposed models can be employed for prediction based only on parameters related to sediment characteristics or wave conditions and geometry of the visible beach the approach is compared with data from the east coast of australia the east coast of north america and the south shore of the mediterranean sea

grain shape analysis a new method for determining representative particle shapes for populations of natural grains abstract the size sorting and shape sorting of gravel bedload by running water often is investigated using identifiable tracer grains that represent the grains within the riverbed a new robust and reproducible method is described for the objective selection of three dimensional shapes that are representative of the variety of shape within any whole sample widespread adoption of the method would ensure comparability between the shape sorting results of different experiments the approach identifies average and extreme grain shapes from natural gravel samples importantly tracer dimensions are derived that form shapes with equal volume thus ensuring that the shape of the tracers is the only transport variable the method is tested on seven gravel samples from a range of fluvial beach and scree slope environments as well as different sieve sizes initially measurements of the short s intermediate i and long l orthogonal axes of clasts are made from selected sieve intervals that represent the spread in the size distribution of the natural gravel shapes are identified to be within the realms of the observed shapes of the sampled population four extreme shapes are identified a blade a rod a spheroid and a discoid as well as a median form the starting points of the analysis are the zingg ratios s i and i l however these quantities require polar coordinate transformation to be useful in shape selection the polar coordinate quantities form a joint probability density function that is the product of the marginal distributions of the new shape indices and the axes of the shape diagram utilizing and combining extreme percentiles of these latter distributions identifies the required shapes a reverse transformation returns these selected quantities back into zingg indices finally using the intermediate axial dimensions and the volume ratio the final tracer dimensions are found

carbon isotope chemostratigraphy and sedimentary facies evolution of the ediacaran doushantuo formation in western hubei south china abstract the doushantuo formation of south china consisting of intercalated siliciclastic and carbonate rocks which exhibit considerable variation in thickness and sedimentary facies is one of the key sedimentary units in the world for understanding ediacaran geobiological processes however stratigraphic correlation and sedimentary facies evolution of the doushantuo formation remain controversial sedimentary facies analysis of the well known sections of the yangtze gorges area and new sections in northern yichang western hubei indicate that the doushantuo succession in the yangtze gorges area was deposited in an offshore intra shelf basin within the yangtze platform in contrast the doushantuo formation in the northern yichang area which is characterized by one or a few phosphate rich horizons represents deposition on the subtidal or intertidal shelf and so is similar to the succession in the weng an area central guizhou province the carbon isotope profiles of the different sections exhibit significant variation which is interpreted to result from facies differences sequence and high resolution carbon isotope stratigraphy have clarified problematic correlations and the temporal relationship between fossil assemblages of the doushantuo formation on the yangtze platform the results confirm that a prominent negative 13ccarb excursion baince nadir down to 5 in the middle portion of the second sequence of the doushantuo formation is a widely traceable event baince together with three other 13ccarb excursions namely cance at the base wance near the first sequence boundary near the middle and dounce at the top of the doushantuo formation constitute a complete carbon isotope profile for the doushantuo formation that reflects contemporaneous seawater and so serves as a reference chemostratigraphic profile for global stratigraphic correlation and for evaluating the chemical evolution of seawater during the ediacaran period

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

the dynamics of the onset of frictional slip the way in which a frictional interface fails is critical to our fundamental understanding of failure processes in fields ranging from engineering to the study of earthquakes frictional motion is initiated by rupture fronts that propagate within the thin interface that separates two sheared bodies by measuring the shear and normal stresses along the interface together with the subsequent rapid real contact area dynamics we find that the ratio of shear stress to normal stress can locally far exceed the static friction coefficient without precipitating slip moreover different modes of rupture selected by the system correspond to distinct regimes of the local stress ratio these results indicate the key role of nonuniformity to frictional stability and dynamics with implications for the prediction selection and arrest of different modes of earthquakes

morphodynamics of a boulder beach putuo island se china coast the role of storms and typhoon abstract in this paper we examine the sedimentological properties and morphodynamic evolution of a boulder beach at huayanpeng cape on putuo island off the southeast china coast focus is given to the formation of the boulder beach 256 2000 mm diameter and resulting morphology in relation to high energy storms and seasonal typhoon holocene sea level rise to the present position at ca 7000 6000 yrs bp provides a long term window for the formation of the beach the beach is primarily characterized from east to west by 1 the convex to concave beach morphology 2 reduced longest axis of the skeleton boulders 3 decreased flatness of the skeleton boulders and 4 greater sphericity of the skeleton boulders infilling cobbles pebbles in the beach demonstrate a bi modal distribution corresponding to dominant sizes of 100 250 mm and 50 100 mm in diameter on the eastern beach and western beach respectively this reflects changed intensity of storm waves alongshore multiple peaks of the distributions of infilling clasts for the western beach supratidal probably reflect storm and calm weather sedimentation statistically both the skeleton boulders and infilling clasts follow a distribution reflecting the high energy control of beach formation and the dominance of crushing in boulder size reduction a boulder transport model applied in the present study further reveals that boulders with an a axis length of 500 1000 mm the dominant component on the beach move under a wide range of wave conditions depending on wave height and wave period with a cluster of critical wave heights in the range 2 6 m and wave periods of 5 15 s

tsunamis as geomorphic crises lessons from the december 26 2004 tsunami in lhok nga west banda aceh sumatra indonesia abstract large tsunamis are major geomorphic crises since they imply extensive erosion sediment transport and deposition in a few minutes and over hundreds of kilometres of coast nevertheless little is known about their geomorphologic imprints the december 26 2004 tsunami in sumatra indonesia was one of the largest and deadliest tsunamis in recorded human history we present a description of the coastal erosion and boulder deposition induced by the 2004 tsunami in the lhok nga bay located to the west of banda aceh northwest sumatra the geomorphological impact of the tsunami is evidenced by beach erosion some beaches have almost disappeared destruction of sand barriers protecting the lagoons or at river mouths numerous erosion escarpments typically in the order of 0 5 1 5 m when capped by soil and more than 2 m in dunes bank erosion in the river beds the retreat along the main river is in the order of 5 15 m with local retreats exceeding 30 m large scars typically 20 50 cm deep on slopes dislodgement of blocks along fractures and structural ramps on cliffs the upper limit of erosion appears as a continuous trimline at 20 30 m a s l locally reaching 50 m the erosional imprints of the tsunami extend to 500 m from the shoreline and exceed 2 km along riverbeds the overall coastal retreat from lampuuk to leupung was 60 m 550 000 m 2 and locally exceeded 150 m over 276 000 m 3 of coastal sediments were eroded by the tsunami along the 9 2 km of sandy coast the mean erosion rate of the beaches was 30 m 3 m of coast and locally exceeded 80 m 3 m the most eroded coasts were tangent to the tsunami wave train which was coming from the southwest the fringing reefs were not efficient in reducing the erosional impact of the tsunami the 220 boulders measured range from 0 3 to 7 2 m large typically 0 7 1 5 m with weights from over 50 kg up to 85 t we found one boulder less than 1 m large at 1 km from the coastline but all the others were transported less than 450 m 30 m and the moderate tsunamis height

rocky coasts their role as depositional environments abstract the role of rocky coasts as depositional environments has been generally neglected by rock and depositional coast workers although rock coasts can be hostile sedimentary environments they frequently host a variety of deposits consisting of mixes of boulders and megaclasts to sand and cobbles these deposits include pockets of sand and pebble trapped in topographic depressions or at the foot of scarps and cliffs isolated boulders pocket beaches trapped between headlands and sand to boulder beaches in shallow bays exposed to strong wave action the tectonic setting which is reflected in the degree of geological heterogeneity alongshore together with the wave regime and other elements of the morphogenic environment help to determine the amount and mobility of the sediment and consequently whether it plays an essentially abrasional or protectional role many beaches have a resistant rock foundation which will modulate their response to rising sea level and possibly increased storminess during this century wave refraction and temporal and spatial changes in sediment abrasional and protectional efficacy influence the development of crenulated planforms on coasts with a high degree of geological heterogeneity and possibly on more geologically homogeneous coasts with longshore variations in cliff height or in the amount of sediment theory suggests that these coasts may develop equilibrium planforms with uniform rates of erosion in bays and on headlands or they may undergo a series of cyclical transformations involving alternating increases and decreases in the depth of the bays relative to the headlands

large boulder accumulations by extreme waves along the adriatic coast of southern apulia italy abstract the adriatic coast of southern apulia italy is marked by the presence of large boulder accumulations boulders are up to 8 t in weight and arranged either in small groups or rows composed of a few imbricated elements the lower surface of some of the boulders is covered by biogenic encrustation which suggests that they were possibly carved from the mid or sublittoral zone and that they capsized during their transport other boulders detached from the supratidal zone have their surface affected by tilted rock pools new horizontal solution pans are continually forming a detailed survey of a large boulder accumulation was carried out at torre santa sabina direct observations were also made concerning the carving out and transportation of one single boulder during the severe storms in that area on january 4th 2002 and on january 12th 2003 collated data from both the survey and the direct observations including some radiocarbon age determinations and hydrodynamic calculations suggest that the studied accumulation was due to the superimposed effects of one or two tsunami as well as of storm waves tsunami would be responsible for the detachment and transportation of the largest boulders while storm waves may have been responsible for the carving out and transportation of the newer smaller blocks and for moving once again the largest boulders it was in this way that a typical boulder accumulation was produced the collated data suggest that two tsunami may have recently struck the adriatic coast of southern apulia the first possibly took place on the dalmatian coast as a result of the earthquake on april 6 1667 which destroyed ragusa modern day dubrovnik the second tsunami would have accompanied the strong earthquake which took place in southern apulia on february 20 1743