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

sector collapse sedimentation and clast population evolution at an active island arc volcano stromboli italy sciara del fuoco is the subaerial part of a partially filled sector collapse scar that extends to 700 m below sea level on stromboli volcano the collapse occurred 2200 m and 10 km from the shore to the nnw a fan shaped mounded feature comprises debris avalanche deposits 4 km3 from two or more sector collapses volcaniclastic density currents originating from sciara del fuoco follow the topographic margin of the debris avalanche deposits although overbank currents and other unconfined currents widely cover the mounded feature with turbidites historical recorded eruptive activity in sciara del fuoco is considerably less than that which occurred earlier and much of the partial fill may have formed from eruptions soon after the sector collapse it is possible that a mass of eruptive products similar to that in the collapse scar is dispersed as volcanogenic sediment in deep water of the tyrhennian basin evidence that the early post collapse eruptive discharge was greater than the apparent recent flux 2kg s counters suggestions that a substantial part of stromboli s growth has been endogenous the partial fill of sciaria del fuoco is dominated by lava and spatter layers rather than by the scoria and ash layers classically regarded as main constituents of strombolian cinder cones much of the volcanic slope beneath the vents is steeper than the angle of repose of loose tephra which is therefore rapidly transported to the sea delicate pyroclasts that record the magmatic explosivity are selectively destroyed and diluted during sedimentary transport mainly in avalanches and by shoreline wave reworking and thus the submarine deposits do not record well the extent and diversity of explosive activity and associated clast forming processes considerable amounts of dense non vesicular fine sand and silt grains are produced by breakage and rounding of fragments of lava and agglutinate the submarine extension of the collapse scar and the continuing topographic depression to 2200 m below sea level are zones of considerable by passing of fine sand and silt which are transported in turbidity currents evidently volcanogenic sediments dispersed around island volcanoes by density currents are unlikely to record well the true spectrum and relative importance of clast forming processes that occurred during an eruption marine sedimentary evidence of magmatic explosivity is particularly susceptible to partial or complete obliteration unless there is a high rate of discharge of pyroclastic material into the sea

submarine features of modern open sea fan deltas huon peninsula papua new guinea a series of fan deltas has been delineated in water depths between 300 and 1900 m along the 75 km shelf and slope of the northern huon gulf papua new guinea using the hawaii mr1 side scan system comparison of these fan deltas suggests that submarine slope profiles and feeder systems i e type and size are the most important factors controlling the construction and the geometry of the submarine fan deltas fan deltas are fully developed only at large rivers in areas with a ss shaped slope profile six zones are recognised on the ss profiled fan delta surface based on the submarine topographic characteristics dominant acoustic facies and slopes the zonation differs from that of prior and bornhold 1989 from fan deltas in a british columbian fjord in terms of magnitude slope profiles and submarine channelling patterns the huon fan deltas represent larger more dynamic deep water delta systems with individual fan deltas up to 200 km2 the main parts of the huon fan deltas are deposited below 500 m 5 km from river mouths large quantities of coarse grained sediments are found in water depths over 1400 m 13 km from river mouths the relief of the interfingered narrow ridges and gullies in zone 3 is up to 100 m zone 6 has a slope gradient of 4 4 much steeper than zone 5 1 5 the huon fan deltas can not be easily fitted into any of the existing classification they warrant a comparative study of fan deltas with similar feeder systems but different slope profiles and with similar slope profiles but different feeder systems in the same basin regime delta classification and nomenclature needs to reflect seven attributes feeder system basin dynamics water depth depth ratio slope profile dominant slope process delta front grain size and geometry

natural hazards of shoreline bluff erosion a case study of horizon view lake huron abstract assessment of hazard of erosion of shoreline bluffs requires an understanding of the natural processes and human use in these high risk areas as an important component associated with erosion and natural evolution bluff shorelines alongshore sediment transport is an essential process in defining the hazard associated with bluff erosion the objective of this study is the integration of an understanding of alongshore sediment transport into a proposed management framework for cohesive bluff shorelines a study of a ten kilometre area along the southeastern lake huron shoreline at the cottage community of horizon view north of goderich ontario examines the natural and human components which have led to the development of bluff erosion hazards although dominant sediment transport is north to south alongshore the pattern of wave refraction during south and southwest waves suggests frequent northward transport of material from the 30 meter high bluffs at the site examination of beach sediments and bluff conditions support this finding and indicate long term sediment supply and bluff instability planning of future development at this location must appreciate the potential for continued bluff erosion and the study results suggest that when combined with other factors such as wave energy bluff morphology groundwater conditions vegetation cover land uses and impacts of fluctuating lake levels studies of alongshore sediment transport can be a useful tool to assist in management of cohesive coastlines and understanding the natural hazard of bluff erosion in developed coastal areas a management framework for cohesive bluffs attempts to integrate an understanding of natural processes with human uses and land use policies in order to identify assess and select a preferred management option reflecting this understanding

rapid and widespread dispersal of flood sediment on the northern california margin the dispersal of flood sediment from small river systems is a poorly studied yet potentially important aspect of active continental margin sedimentation in january 1995 during a flood with a 30 yr return period the eel river northern california delivered an estimated 25 3 106 t metric tons of fine grained 62 m sediment to the ocean the flood formed a distinct layer on the sea bed that was centered on the 70 m isobath extended for 30 km along shelf and 8 km across shelf and was as thick as 8 5 cm but contained only 6 106 t of sediment thus 75 of the flood derived sediment did not form a recognizable deposit but was instead rapidly and widely dispersed over the continental margin stratigraphic models of and compilations of sediment flux to active continental margins need to take the dispersive nature of small river systems into account

a large rockslide debris avalanche in cohesive soil at pink mountain northeastern british columbia canada abstract in early july 2002 a large rockslide debris avalanche occurred on the west slope of the pink mountain anticline in northeastern british columbia 57 04 n 122 52 w the slopes have been subjected to previous deformation and landsliding pre and post slide digital elevation models dems were created from aerial photography approximately 1 04 m m 3 of sandstone and shale travelled nearly 2 km from an elevation of 1460 m to 1010 m the landslide has a fahrboschung of 11 6 and covered 43 ha the rock debris entrained a certain amount of fine textured till and colluvium increasing its volume by 15 this entrainment caused partial liquefaction of the underlying soil thereby enhancing the mobility of the landslide we used a bingham rheological model to dynamically model the landslide with excellent correspondence between the analysis of the actual observed behaviour of the landslide

twentieth century floods recorded in the deep mediterranean sediments flood generated turbidity currents represent an important process of marine sedimentation however no deposit related to this process has yet been described at sea turbiditic sequences cored at 2000 m water depth in the mediterranean show tractive structures and superposition of reverse and normal grading they are related to floods triggered during the twentieth century deposits from flood generated turbidity currents have a great impact on the interpretation of deep ocean paleoclimate records obtained near continental margins by linking deep marine sedimentary records to continental climatic changes through flood frequency and magnitude implications of this study should help redefine the reservoir character of oil fields in fine grained turbidites

modeling the accumulation and dynamics of beaches on shore platforms a mathematical model was used to study the development and dynamics of beaches on shore platforms the model was based on assumptions that the gradient of the beachface at its seaward edge must be greater than platform gradient beach sediment tends to move landwards and beach occurrence and extent depends upon the amount of sediment available equilibrium beachface gradient was related to breaker height wave period and sediment grain size three grain sizes were used representing fine and coarse sand and pebble two deep water wave sets representing storm wave and west coast swell wave environments and two tidal ranges of 9 1 and 3 3 m runs were made using linear concave and convex platform profiles with gradients ranging between about 0 6 and 8 because platform and beachface gradients are normally quite similar shore platforms are unable to store much sediment for a linear platform with a lower gradient than the beachface sediment first accumulates at the cliff base and then depending on the sediment available extends increasingly seawards beach development first occurs on the gently sloping seaward portions of concave platforms and on the more landward portions of convex profiles the amount of available material partly determines the landward and seaward extent of these beaches respectively although it is also controlled by beachface and platform gradients beaches on shore platforms become thinner and more gently sloping during storms and they may disappear completely depending on such factors as sediment grain size platform gradient the amount of sediment that can be stored during calm conditions wave characteristics and the duration of the storm the response of beaches on rocky coasts to rising sea level will be different from those on sedimentary coasts and will depend in part on the morphology of the rocky foundation

static and dynamic simulation of a 700 m high rock slope in western norway abstract static and dynamic rock slope stability analyses were performed using a numerical discontinuum modelling technique for a 700 m high rock slope in western norway the rock slope has been investigated by the geological survey of norway ngu which has been carrying out rock slide studies for the county more and romsdal in western norway the purpose of numerical modelling was to estimate the volume of the rock mass that could potentially slide under static and dynamic forces this estimation was required to assess the run up heights tsunami in a fjord that could potentially be caused by the rockslide three cases have been simulated for predicting the behaviour of the rock slope first an initial static loading is applied in the numerical model to simulate the prevailing rock mass conditions at the site second saturated and weathered joint conditions are modelled by reducing the residual friction angle along the discontinuities of the rock mass in doing so the model simulates the effect of degradation of discontinuities in the rock slope third a dynamic loading based on peak ground accelerations expected in the area is applied to simulate dynamic earthquake conditions these numerical studies have provided some useful insights into the deformation mechanisms in the rock slope both sliding and rotation of blocks start to occur once the residual friction angle along the discontinuities is reduced and when the region is shaken by a strong earthquake the results indicate that due to variations in the inclination of discontinuities the entire slope does not become unstable and that down slope sliding and rotation of blocks occur mainly on the top layers of the slope within the range of parameter values considered for this study it is unlikely that the whole rock slope can be destabilised the study provides an illustration of how the geo mechanical properties of a rock mass can be integrated in a discontinuum rock slope model which is used for predicting the behaviour of the slope under existing environmental and earthquake conditions this model has helped not only to better understand the dynamics of the rockslide but also to estimate the potential rock volume that can become unstable when subjected to static and dynamic loads

the role of environmental shear and thermodynamic conditions in determining the structure and evolution of mesoscale convective systems during toga coare abstract a collection of case studies is used to elucidate the influence of environmental soundings on the structure and evolution of the convection in the mesoscale convective systems sampled by the turboprop aircraft in the tropical ocean global atmosphere toga coupled ocean atmosphere response experiment coare the soundings were constructed primarily from aircraft data below 5 6 km and primarily from radiosonde data at higher altitudes the well documented role of the vertical shear of the horizontal wind in determining the mesoscale structure of tropical convection is confirmed and extended as noted by earlier investigators nearly all convective bands occurring in environments with appreciable shear below a low level wind maximum are oriented nearly normal to the shear beneath the wind maximum and propagate in the direction of the low level shear at a speed close to the wind maximum when there is appreciable shear at middle levels 800 400 mb convective bands form parallel to the shear with

the zymoetz river rock avalanche june 2002 british columbia canada abstract on june 8 2002 the pacific northern gas pipeline in the zymoetz river valley was severed by a large debris flow the event initiated as a rock avalanche in glen falls creek a tributary of the zymoetz river the rock avalanche involved 1 106 m3 of volcaniclastic bedrock and travelled through a complex flow path to finally deposit a large fan in the main zymoetz river approximately half of the debris volume was deposited in the cirque basin at the head of the valley with the rest deposited in the channel and the fan examination of the initiation zone showed a very persistent slightly curved joint set that forms the main sliding surface for the failed block with a dip of 45 and dip direction of 300 a geographic information system gis was used to examine the event and allowed for further interpretation of field data preliminary dynamic analysis indicates that the event reached velocities of up to 34 m s comparison of the zymoetz river rock avalanche zrra with other similar events from the literature indicates that it exhibited similar mobility and velocities as evidenced from the literature these long runout events can cause significant damage and have the potential to be a very high risk as forestry and recreation activities spread further into remote areas

new sonar evidence for recent catastrophic collapses of the north flank of tenerife canary islands previous sonar surveys show that the north flank of tenerife has been subject to at least four major landslides during the past 1 ma the youngest icod affected the region to the north of the teide pico viejo complex the world s third highest oceanic volcano recently we obtained the first detailed acoustic images of icod using a deep tow side scan sonar the images suggest that tenerife s north flank has experienced at least two types of flow deposit in the recent past the older flow deposit icod i is characterised by a 15 to 20 km wide 65 km long chaotic debris avalanche deposit which includes several very large blocks we believe the deposit to be 170 ka and that it represents the mass wasting products of the canadas edifice remnants of which are now found in the las canadas caldera wall the younger flow deposit icod ii associated with a shute in its proximal part appears to have produced a less chaotic deposit in its distal part which clearly preserves flow structures such as latitudinal boulder ridges and longitudinal shear structures the sonar images cannot determine how much younger icod ii is than icod i although it is likely that they are a consequence of the same lateral collapse event there is evidence from the shute area for erosional scour and sediment deposition since the icod landslide if this is correct then it suggests that mass wasting is an ongoing process that has already started to modify the teide pico viejo complex itself

alluvial and coastal hazards caused by long range effects of plinian eruptions the case of the lattari mts after the ad 79 eruption of vesuvius abstract the lattari mountains a limestone ridge about 20 km south of vesuvius received 1 2 5 m of fallout from the famous plinian eruption of ad 79 as demonstrated by many residual outcrops of thick volcanoclastic debris flow and alluvial deposits referred to here as the durece unit the pyroclastic fall was soon followed by rapid erosion and landsliding that produced 1 decametre scale aggradation of some narrow valley floors 2 reactivation of alluvial fans and 3 growth of new fan deltas extending as far as 500 m at the coast this response was primarily due to the steep topography of the area and the high erodability of the pyroclastic materials light and cohesionless pumice fragments several geo archaeological data indicate that the accelerated sedimentation had a duration of the order of decades and was followed by rapid dissection of the durece unit deposits and fast dismantling by wave action of the newly created fan deltas this case highlights the need to consider the possibly catastrophic reaction of fluvial and coastal systems to large explosive eruptions even in non volcanic terrains at some distance from the volcano

large scale volcanic cone collapse the 1888 slope failure of ritter volcano and other examples from papua new guinea a largely submarine avalanche amphitheatre that formed catastrophically in 1888 on ritter volcano has been identified from a bathymetric survey collapse of the volcano in 1888 therefore is considered to have been caused by rapid large scale slope failure rather than by cauldron subsidence as previously supposed escarpments of pre historic slope failures are common on other papua new guinea volcanoes directions of avalanching on some volcanoes in the bismarck volcanic arc appear to be controlled by a regional stress pattern and those for some volcanoes in the fly highlands province on mainland papua new guinea point away from the regional centre of pliocene uplift large amphitheatres such as at doma peaks in the fly high lands province probably originated by multiple collapses

low sea level emplacement of a very large late pleistocene megaturbidite in the western mediterranean sea large volume turbidites termed megaturbidites or megabeds result from catastrophic slope failures and the associated downslope transport of enormous quantities of sediment from continental margins to the deep sea such large sediment failures can generate tsunamis and in terrains underlain by gas hydrates clathrates may be associated with the release of substantial amounts of the greenhouse gas methane it has been proposed that the megaturbidite events may be triggered by seismic activity or may result from gas hydrate release itself caused by a lowering of hydrostatic pressure on clathrates as a result of low sea level previous conclusions on the significance of sea level change however have been conditional because of the lack of absolute times of turbidite emplacement here we use accelerator mass spectrometry radiocarbon dating in five widely spaced cores to constrain the date of emplacement of a large volume 500 km3 bed in the balearic basin of the western mediterranean this turbidite is exceptional in its magnitude and represents the main sedimentation event in the balearic basin over the past 100 kyr our data provide an estimate of 22 000 calendar years before present for emplacement of the megabed a time when sea level stood at its lowest level during the last glacial maximum the coincidence of these dates is consistent with emplacement due to clathrate destabilization caused by low sea level although other triggering mechanisms such as seismic shock cannot be ruled out

sediment transport processes on an active submarine fault escarpment gulf of corinth greece abstract sediment transport processes on the escarpment of a listric fault in the tectonically active and terrigenous sediment dominated corinth graben in greece are studied using 3 5 khz and airgun profiles and sidescan sonar images the whole of the slope area is affected by gravitational mass movements slumps debris mud flows and liquified and turbidity flows in canyon fan systems large volumes of sediment are transported through slumping debris mud and turbidity flows into the basin here they build coalescing fans which consist of intercalations of debris flow deposits and turbidites in delta front slope fan apron systems sediments are transported radially downslope through slumping debris mud flows liquified flows and high density turbidity flows into the basin where they build coalescing fan aprons these consist of massive homogenized deposits fluxoturbidites in shelf slope systems retrogressive rotational slumping is the dominant instability feature however due to the sharp increase in the slope gradient caused by the slumping debris and turbidity flows are triggered the major factors responsible for triggering gravitational mass movements in the region are earthquakes high sedimentation rates off the river mouths and heavy rainfalls and high seas these mass movements appear to occur at least once every 2 yrs as indicated by the failure of submarine cables

forecasting hazard scenarios and implications for the evaluation of countermeasure efficiency for large debris avalanches abstract the key objective of a slope failure study is to reduce deaths injuries and property damage predictions of slope failures are mandatory to reduce hazard and vulnerability of elements at risk with appropriate warning policy and properly designed countermeasures numerical modelling has been recently used as an approach to back analyse real events but few attempts have been carried out to forecast potential failure scenarios recently a debris avalanche involving about 1 2 million m 3 of debris and a nearby debris slide flow with failure volume of 0 1 million m 3 occurred in the italian prealps from the accumulation of a paleo landslide field surveys and monitoring revealed that the upper part of the slope above the largest recent landslide is unstable with a possible failure volume between 1 and 1 5 million m 3 we conducted comprehensive fieldwork and analyses including geological and geomorphological surveys compilation of a landslide inventory map collection of rainfall records study of triggering mechanisms and geotechnical properties of the failed materials slope stability analyses and back analyses of the runout phase of the landslide events through a series of slope stability analyses the possible failure volume sliding surface and topography are estimated consistent with field monitoring data furthermore with the help of calibration through back analyses of the past landslide events we assign a given degree of danger to slope elements with analogous conditions we then numerically predict the runout patterns and mobility of the potential instabilities the effectiveness of the planned passive countermeasures for potential zoning management is evaluated

measuring flood output from 110 coastal watersheds in california with field measurements and seawifs the 1300 km long california coast receives output from watersheds that range from 10 km 2 within the coastal mountain ranges to 120 000 km 2 for the drainage basins of the sacramento and san joaquin rivers results from a combination of field and remote sensing data modeling and digital techniques show that during the el nino winter of 1998 the impact of sediment and water transport on nearshore waters from coastal watersheds was spatially extensive varied with depth and was comparable to the impact of output from large rivers the mass of sediment estimated from seawifs data for 25 discrete and coalesced buoyant river plumes emanating from 110 watersheds was 2 2 10 6 t although the mass of all of the plumes represents only 1 2 of the total sediment output from the rivers the plumes covered an area of 29 500 km 2 of coastal waters an important cautionary note is that the surface plumes visible in the remote sensing data even though nearly coincident with flooding do not represent mass output from the rivers

the el coyote fan delta a wave dominated example from the gulf of california mexico abstract modern fan deltas from the gulf of california are common along the high relief cliffed peninsular margin most of the fan deltas are wave dominated affected also by the longshore drift human impact on these fan deltas is minimal thus el coyote is an example useful for obtaining a better understanding of fan delta depositional systems in the stratigraphic record local rapid changes reflect the interaction of short term summer flash floods and wave energy which rapidly removes the evidence of high discharges the baja california peninsula has been relatively stable at least in the last few hundred thousand years with an uplift rate of 100 mm ka thus changes in sea level and climate have been recorded on the fan delta as 1 pleistocene marine and fluvial terraces possible stages 5e or 5c 2 erosion of the subaerial portion due to lowering of sea level from a 1 to 1 5 high sea level standard in the last 6000 years and a decrease in the rate of sediment discharge and 3 the submerged fan form at a water depth of 40 m related to the high sea level stands of stages 2 28 ka and 3 40 45 ka

on the biogeochemical response of a glacierized high arctic watershed to climate change revealing patterns processes and heterogeneity among micro catchments our novel study examines landscape biogeochemical evolution following deglaciation and permafrost change in svalbard by looking at the productivity of various micro catchments existing within one watershed it also sheds light on how moraine talus and soil environments contribute to solute export from the entire watershed into the downstream marine ecosystem we find that solute dynamics in different micro catchments are sensitive to abiotic factors such as runoff volume water temperature geology geomorphological controls upon hydrological flowpaths and landscape evolution following sea level and glacial changes biotic factors influence the anionic composition of runoff because of the importance of microbial so42 and no3 production the legacy of glaciation and its impact upon sea level changes is shown to influence local hydrochemistry allowing cl to be used as a tracer of thawing permafrost that has marine origins however we show that a glacial signal dominates solute export from the watershed therefore although climatically driven change in the proglacial area has an influence on local ecosystems the biogeochemical response of the entire watershed is dominated by glacially derived products of rapid chemical weathering consequently only the study of micro catchments existing within watersheds can uncover the landscape response to contemporary climate change

source to sink sediment transfers environmental engineering and hazard mitigation in the steep var river catchment french riviera southeastern france steep coastal margins are potentially subject to mass wasting processes involving notable landslide activity and sediment evacuation downstream by steep gradient streams sediment transfer from short source to sink segments coupled with mountain hydrological regimes regulate patterns of river channel aggradation and coastal sediment supply in such geomorphic settings on the steep french riviera margin sediment transfers from existing landslides or from various minor mass wasting processes to stream channels may result following bursts of heavy concentrated rainfall high magnitude flooding and massive sediment transport downstream are generally related to unpredictable extreme rainfalls both mass movements and channel sediment storage pose serious hazards to downvalley settlements and infrastructure a consideration of channel sediment storage patterns in the var river catchment the most important catchment in this area highlights two important shortcomings relative to environmental engineering and hazard mitigation practices in the first place the appreciation of geomorphic processes is rather poor this is illustrated by the undersized nature of engineering works constructed to mitigate hazards in the upstream bedload dominated channels and by the unforeseen effects that ten rock dams constructed in the early 1970s have had on downstream and coastal sediment storage and on sediment dispersal patterns and consequently valley flooding secondly planners and environmental engineers have lacked foresight in valley and coastal management issues on this steep setting notably as regards the reclaimed areas of the lower var channel and delta liable to flooding urbanization and transport and environmental engineering works have progressively affected patterns of storage and transport of fine grained sediments in the lower var channel and delta meanwhile the problems raised by these changes have not been adequately addressed in terms of scientific research a necessary future step in bettering the engineering solutions implemented to contain natural hazards or to harness water and sediment resources is that of fine scale analysis of source to sink sediment transfer processes of sediment budgets of time scales of storage in stream channels and finally of high magnitude hydrometeorological forcing events in this area the way all these aspects have been modulated by engineering practices and socioeconomic development should also be an important part of such an analysis

the ischia debris avalanche first clear submarine evidence in the mediterranean of a volcanic island prehistorical collapse sector or flank collapse with related debris avalanches is increasingly recognized as a relatively common volcanic behaviour in particular for large hot spot related oceanic islands here we report the case of a catastrophic collapse that occurred at ischia volcanic island in prehistorical times and was driven by the volcano tectonic uplift of mt epomeo the major relief of the island the collapse left a subaerial to submarine horseshoe scar on the southern flank of the island and generated a debris avalanche incorporating thousands of giant blocks dispersed as far as 50 km from the island during the emplacement part of the debris avalanche evolved into a debris flow covering an area of 250 300 km2 this constitutes the first clear evidence of a submarine debris avalanche in the mediterranean sea the major collapse was followed and probably also preceded by recurrent less catastrophic terrestrial and underwater failures two other undersea hummocky deposits are found north and west of the island and might tentatively be correlated to the major southern collapse such volcanic behaviour previously unknown for ischia volcano has likely triggered tsunami waves over the entire bay of naples raising the question of their impact on prehistorical historical communities

sedimentology of high stage flood deposits of the tagus river central spain abstract this paper details the sedimentology of high stage flood deposits with the definition of sedimentary environments and their characteristic sequences along two bedrock reaches of the tagus river central spain high stage flood deposits accumulated in bedrock canyons include slackwater flood deposits swd and other types of deposits located at flow separation zones and associated with slow moving flow 1 these flood deposits are common indirect indicators of flood stages used in palaeoflood studies for estimating the discharges associated with quaternary floods depositional environments of flood deposits include 1 channel widening 2 canyon expansion 3 bedrock obstacles and 4 backflooded areas along tributary streams these flood deposits can be found associated with other non fluvial environments namely aeolian reworked and slope washflow facies channel widening due to flood stage variations comprises internal and external zones of the channel margins and their characteristic sequences contain similar facies to those of alluvial floodplains canyon expansion environments favour vertical accretion of slackwater units and the development of flood deposit benches which contain four sequences related to bench elevation and distance from the channel s main thread of flow at the lee side of bedrock obstacles characteristic sedimentary sequences are dominated by reverse flow structures e g climbing ripples migrating upstream due to eddies with a high sand concentration flood deposits located within tributary mouths contain typical sequences of reworked floodplain deposits backflooding of tributaries during flood stages produces deposition from suspension of sand silt and clay within three sequences characterised by non structure or parallel lamination and intense bioturbation a better understanding of the flood deposit sequences may contribute to the characterisation of flood magnitudes and flood hydraulics and can also be applied to some ancient depositional environments

the morphology of the submarine flanks of volcanic ocean islands a comparative study of the canary and hawaiian hotspot islands the submarine flanks of volcanic islands are shaped by volcanic constructional processes landslides erosion sediment deposition and tectonic movements we use a newly acquired multibeam sonar dataset from the westerly canary islands el hierro la palma and tenerife to develop a comparison with the hawaiian islands which suggests differences in the processes constructing and modifying their flanks landslides affect the flanks of both island groups debris avalanches fast moving shallow landslides have left smooth chutes and blocky deposits in both cases but blocks within some hawaiian avalanche deposits are markedly larger we attribute the larger block sizes in the hawaiian islands to the fact that their avalanches were relatively unconfined whereas many canary and hawaiian avalanches with small block sizes appear to have been constrained down narrow chutes forcing interactions between blocks within the flows and encouraging disintegration furthermore the hawaiian avalanches with the largest blocks initiated near sea level whereas many of the canary avalanches initiated above sea level so hydraulic resistance of water entering cracks may be an additional factor in resisting block disintegration during flow slow moving deep seated slumps or volcanic spreading have produced submarine benches and tabular escarpments due to thrust faulting adjacent to several hawaiian rift zones but are not well developed in the canaries although volcanic morphology is partly obscured by sedimentation in the canaries we are able to interpret lava terraces around the deep flanks of el hierro which are similar to those found in the hawaiian islands however cones rather than terraces are the most common volcanic forms in the canary islands implying that flank eruptions have involved magma with significant volatile contents assuming that volatile contents dictate whether cones or terraces are formed these differences may ultimately originate from the different building rates of the two island groups for example the lack of evidence for high level magma chambers in the canaries associated with their lower outputs implies that there is less possibility for degassing of magma below the summit before lateral intrusion down rift zones hence cones rather than lava terraces are more commonly observed the apparent lack of slumping or volcano spreading could also reflect a lack of driving pressure from extensive high level magma chambers in the canaries

characterization of debris avalanche deposits in japan abstract seventy one debris avalanche deposits are identified from 52 japanese quaternary volcanoes the structures of these volcanoes are mostly stratovolcanoes and lava domes no avalanche deposit is found in calderas pyroclastic cones or maar volcanoes debris avalanche deposits are found in 18 of all quaternary volcanoes or 25 of quaternary stratovolcanoes and lava domes the ratio rises to 49 when considering only active stratovolcanoes and lava domes at least five debris avalanche deposits have formed since 9th century the maximum height difference of sliding h for each debris avalanche ranges from 200 to 2400 meters and the maximum runout distance of sliding l ranges from 1 6 to 32 km the ratio h l ranges from 0 2 to 0 06 and becomes smaller in larger debris avalanches they are more mobile than landslides in non volcanic areas volume is within a range of 0 03 and 9 km 3 there is no relation between the direction of sliding and the regional horizontal compressional stress axis at the site of a volcano two dimensional computer simulations of avalanches using a simplified physical model are made the maximum velocity is mainly controlled by the length of steep slope

correlation between rate of sea level change and frequency of explosive volcanism in the mediterranean volcanic activity has frequently been linked to quaternary environmental change either by driving climate modification1 2 or in response to environmental changes3 although a link has been established between large explosive eruptions and small 0 5 c brief 1 2 years falls in global temperatures4 both the evidence and mechanisms responsible for longer episodes of eruption induced planetary cooling remain questionable1 2 5 6 in contrast recent research based on ice core data suggests that rapid climate changes during the past 110 000 years increased explosive volcanic activity7 here we present a statistical analysis relating the frequency of explosive activity of mediterranean volcanoes based on dated8 9 10 11 tephra layers in deep sea sediment cores to the rate of late quaternary sea level change the nonlinear correlation between the two is tentatively explained in terms of dynamic responses of the volcanoes to stress related influences on various spatial scales the correlation supports a mechanism or mechanisms by which the climate driven growth and decay of large ice sheets can influence the eruptive chronologies of distant volcanic edifices via changes in global sea level