the anatomy and provenance of thick volcaniclastic flows in the cretan basin south aegean sea abstract santorini volcano has been the largest source of volcaniclastic sediment in the eastern mediterranean during the late quaternary a dozen cores from the cretan basin south of santorini have sampled two megabeds that consist of gravity emplaced volcaniclastic sequences the uppermost megabed u consists of a succession of five u 5 u 1 base cut out turbiditic units lower megabed a is a single turbiditic event only the uppermost u 2 and u 1 turbidites are separated from the underlying beds by hemipelagic marls the texture and composition of the u and a megabeds closely match the texture and composition of the fine vitric ash of the minoan deposits on santorini islands dating from about 3500 yr bp these megabeds are therefore attributed to rapid accumulation of separate gravity flows fed by the minoan eruption except for the upper u 2 and u 1 turbidites deposited from subsequent gravity flows transporting eroded volcaniclastic sediments with the exception of the margin south of santorini dozens of cores retrieved around the margins of the cretan basin have a continuous late quaternary succession that shows no evidence for massive sediment remobilization into the deeper basin including the passage of the minoan tsunami extensive high resolution 3 5 khz records revealed the acoustic character architecture and distribution of the u and a megabeds and four underlying late quaternary volcanogenic megabeds in the cretan basin the acoustic facies of megabeds are typical of megaturbidites and consist of an upper transparent lower velocity layer that corresponds to the fine grained upper turbiditic silt and clay section and a lower strongly reflective higher velocity section that corresponds to the lowest coarser grained base of the turbidite that is developed over a sharp erosional surface penetration of the high resolution records reveals the existence of at least six megabeds correlation with core lithology and the physical properties of the various lithofacies including down core velocity profiles has allowed us to determine the thickness and volumes of the upper four megabeds which are u 9 m thick volume 3 7 km 3 a 25 m thick volume 12 2 km 3 b 22 m thick volume 10 3 km 3 c 15 m thick volume 8 km 3 these thick megabeds are the uppermost products of repeated explosive eruption of santorini in the late quaternary calculated sedimentation rates from and after the minoan eruption are 9 4 m 1000 yr that rise to over 15 7 m 1000 yr if megabed b was also deposited during this eruption

exhumation of messinian evaporites in the deep sea and creation of deep anoxic brine filled collapsed basins abstract the first part of the paper summarizes some basic concepts concerning a the distribution of messinian evaporites in the deepest parts of the mediterranean sea and b the mediterranean ridge accretionary wedge and its peculiar characteristics deriving from the presence of a substantial evaporitic body in the deforming sedimentary prism then five brine filled anoxic collapsed basins tyro bannock urania atalante and discovery discovered from 1983 to 1994 are presented and discussed in their physiographic geologic hydrologic and geochemical characters high density brines deriving from submarine dissolution of outcropping or subcropping evaporites accumulate at the bottom of collapsed basins if they are not swept away by submarine currents the interface separating normal sea water from high density brines is sharp with a density contrast of about 20 and lies at 3200 3500 m below sea level strong bacterial activity is developing at the interface and living bacteria have been recovered from the anoxic salty brines thickness of the brines may be up to 500 m thermal stratification has been observed in three brine lakes exhumation and dissolution of messinian evaporites in the mediterranean ridge occur in different tectonic settings pull apart basin tyro subducting seamount close to the outer deformation front bannock basin top of a backstop urania atalante and discovery basins chemistry of the brines is strongly variable and suggests dissolution of different layers or levels of the messinian suite discovery brines are the saltiest ever recorded in natural environment their saturation in mg chloride bischofite the end product of sea water evaporation suggests that the deepest parts of the eastern mediterranean were close to dryness at the end of the salinity crisis strongly supporting the deep basin desiccation model

the 1996 ad delta collapse and large turbidite in lake brienz abstract in spring 1996 ad the occurrence of a large mass transport was detected by a series of events which happened in lake brienz switzerland turbidity increase and oxygen depletion in deep waters release of an old corpse into surface waters and occurrence of a small tsunami like wave this mass transport generated a large turbidite deposit which is studied here by combining high resolution seismic and sedimentary cores this turbidite deposit correlates to a prominent onlapping unit in the seismic record attaining a maximum of 90 cm in thickness it is longitudinally graded and thins out towards the end of the lake basin thickness distribution map shows that the turbidite extends over 8 5 km2 and has a total volume of 2 72 106 m3 which amounts to 8 7 yr of the lake s annual sediment input it consists of normally graded sand to silt sized sediment containing clasts of hemipelagic sediments topped by a thin white clay sized layer the source area the exact dating and the possible trigger of this turbidite deposit as well as its flow mechanism and ecological impact are presented along with environmental data river inflow wind and lake level measurements the combined results indicate that no particular cause i e earthquake explosion flood wind storm lake level change seiche or sediment dredging triggered the 1996 ad large turbidite deposit instead it was due to a delta slope failure most likely caused by normal sediment accumulation

new findings of bronze age homogenites in the ionian sea geodynamic implications for the mediterranean abstract holocene homogenites similar in character and stratigraphic position to those previously recorded in the ionian basin and related to the gigantic tsunami originating from santorini bronze age eruption are described from a core transect crossing the deformation front of the mediterranean ridge east of victor hensen seahill investigations on grain sizes and carbonate content carried out on three cores from three different areas of the ionian basin encompassing the bronze age homogenite revealed important similarities and some differences the most obvious difference concerns the carbonate content which is minimum at the base of the unit in a core close to the messina abyssal plain whereas it is maximum in cores from the western mediterranean and calabrian ridges characterized by the typical cobblestone topography a terrigenous versus pelagic nature of the components is documented and a distal versus local provenance is inferred homogenites are critically compared with unifites a type of re sediment recently described from the eastern mediterranean comparison includes in particular a source and sediment transport and b triggering mechanism a substantial difference exists between the sedimentation patterns of the ionian and levantine basins seaward of the calabrian and hellenic arcs in the latest quaternary and the difference contains a clear geodynamic message sedimentation rates increase from the late pleistocene to the holocene in the ionian basin whereas they decrease in the levantine basin the glacio eustatic signal is well expressed in the levantine basin where the source areas are situated consistently in the south or on a passive type aseismic continental margin north african margin in the ionian basin on the contrary the glacioeustatic signal is totally obscured by the strong tectonic signal from the active northern continental margin of the mediterranean

origin and chronology of the augias deposit in the ionian sea central mediterranean sea based on new regional sedimentological data abstract in the ionian sea central mediterranean sea several thick acoustically transparent layers are present including the augias deposit the augias deposit is the most recent thick layer covering the entire floor of the ionian abyssal plain with an average thickness of 10 12 m and a maximum thickness of up to 24 m in the sirte abyssal plain this deposit has also been observed in several adjacent smaller basins in waters deeper than 3000 m its estimated volume is 65 km 3 there are multiple plausible hypotheses regarding its age and triggering event which include the 1600 bc santorini volcanic caldera collapse the 365 ad crete m 8 5 earthquake and other smaller earthquakes such as the 374 ad calabria m 6 3 earthquake and the 361 ad sicily m 6 6 earthquake understanding the cause of this mass transport deposit is crucial for improving the natural hazard assessment of a vast area between southern italy and western greece in this study we propose a new interpretation of the augias deposit in terms of sedimentary processes and origin based on sediment cores collected in the nw ionian sea during the circee cruise onboard r v le suroit in october 2013 the sedimentological analysis of seven piston cores reveals three sedimentary facies corresponding to the augias deposit 1 homogenite 2 megaturbidite and 3 thick sandy turbidite these sedimentary facies are distributed within specific morpho tectonic regions as defined by newly acquired bathymetric data indicating a strong control by transport and depositional processes sixteen radiocarbon dates obtained above and below the augias deposit indicate a possible time window of about 500 years this means that we cannot definitively prove a link to the 365 ad crete earthquake but we regard it as the most likely trigger other depositional models may be plausible but here we propose a sequence of events as follows 1 earthquake shock and possible triggering of submarine mass flow in the eastern part of the ionian sea western hellenic subduction zone 2 tsunami waves amplified by the confined morphology of the sicily and calabria continental shelves inducing an intense re suspension of fine grained sediment and massive destabilization at the heads of submarine canyons triggering turbidity currents 3 gravity driven downslope transport of suspended sediment toward the deep basin and decantation and 4 a final stage of decantation from seiche waves forming the majority of the homogenite facies in the ionian abyssal plain

major features and forcing of high latitude northern hemisphere atmospheric circulation using a 110 000 year long glaciochemical series the greenland ice sheet project 2 glaciochemical series sodium potassium ammonium calcium magnesium sulfate nitrate and chloride provides a unique view of the chemistry of the atmosphere and the history of atmospheric circulation over both the high latitudes and mid low latitudes of the northern hemisphere interpretation of this record reveals a diverse array of environmental signatures that include the documentation of anthropogenically derived pollutants volcanic and biomass burning events storminess over marine surfaces continental aridity and biogenic source strength plus information related to the controls on both high and low frequency climate events of the last 110 000 years climate forcings investigated include changes in insolation of the order of the major orbital cycles that control the long term behavior of atmospheric circulation patterns through changes in ice volume sea level events such as the heinrich events massive discharges of icebergs first identified in the marine record that are found to operate on a 6100 year cycle due largely to the lagged response of ice sheets to changes in insolation and consequent glacier dynamics and rapid climate change events massive reorganizations of atmospheric circulation that are demonstrated to operate on 1450 year cycles changes in insolation and associated positive feedbacks related to ice sheets may assist in explaining favorable time periods and controls on the amplitude of massive rapid climate change events explanation for the exact timing and global synchroneity of these events is however more complicated preliminary evidence points to possible solar variability climate associations for these events and perhaps others that are embedded in our ice core derived atmospheric circulation records

persistent solar influence on north atlantic climate during the holocene surface winds and surface ocean hydrography in the subpolar north atlantic appear to have been influenced by variations in solar output through the entire holocene the evidence comes from a close correlation between inferred changes in production rates of the cosmogenic nuclides carbon 14 and beryllium 10 and centennial to millennial time scale changes in proxies of drift ice measured in deep sea sediment cores a solar forcing mechanism therefore may underlie at least the holocene segment of the north atlantic9s 1500 year cycle the surface hydrographic changes may have affected production of north atlantic deep water potentially providing an additional mechanism for amplifying the solar signals and transmitting them globally

cosmogenic 36cl accumulation in unstable landforms 1 effects of the thermal neutron distribution cosmogenic nuclides produced in situ within minerals at the surface of the earth are proving to be an effective means of assessing geomorphic histories the use of multiple cosmogenic nuclides permits both exposure times and erosion rates to be determined however if two nuclides are produced only by spallation reactions the systematic differences in their accumulation rates depend only on the differences in their production rates and half lives the relatively small differences that result require a high degree of analytical precision to yield useful results in contrast to other spallogenic nuclides sup 36 cl is also produced by low energy neutron absorption which creates a different pattern of production as a function of depth we have measured the thermal flux with depth in a concrete block using sup 3 he filled neutron detectors the measured thermal neutron profile agrees well with predictions from a simple diffusion based thermal neutron distribution model calculations of sup 36 cl production using the model suggest that the use of sup 36 cl along with a purely spallogenic nuclide to determine erosion rates and exposure times should be less sensitive to analytical error than are determinations from two purely spallogenic nuclides 31 refs 7 figs 3 tabs

characterisation of erosional features associated with tsunami terrains on rocky coasts of the maltese islands in recent years there has been a growing body of literature on depositional signatures associated with historic extreme waves on rocky coasts here in the context of the maltese islands we place an innovative focus on evidence of erosional forms the field evidence is concentrated along the ne flank of the islands at a topographically varied range of sites and up to an altitude of 13 m asl a range of forms is broadly classified in terms of their morphologies and the forces responsible for their formation sockets eroded scarps scoured terrains clifftop erosion scars swept terrains and spillways are interpreted as consequences of overwashing of the landscape by an extreme wave or waves these forms are shown to be controlled by flow intensity topography and lithology and especially rock bedding and jointing they comprise the source areas for associated depositional evidence allowing transport paths to be estimated and may significantly enhance the reconstruction of extreme wave events it is likely that similar and additional erosional forms are present elsewhere in the mediterranean domain where comparable lithological and topographic situations are exposed to extreme waves

a new conceptual model for the deposition process of homogenite application to a cretaceous megaturbidite of the western pyrenees basque region sw france abstract the north pyrenean megaturbidite is a 19 63 m exceptional thick bed deposited during the late turonian and extending over more than 90 km in the basque region country sw france its thickness varies from more than 63 m to about 19 m from east mauleon area to west basque coast it represents a total compacted volume of about 90 km3 of carbonates on the field rare sedimentary structures are visible in the turbidite bed they consist of laminar planar lamination and rare cross laminations in the eastern region and antidune like structures in the western region five sites have been sampled with a vertical step of 50 cm to 1 m thin sections have been quantitatively analyzed for counting the terrigeneous fraction the quartz grain size and the mineral orientation the deposits fine westward which suggests a source located in the east of the mauleon basin this is consistent with the quartz grain orientation in the lower part of the megaturbidite the deposits fine upward from medium sand to clayey silt this is consistent with the classical definition of homogenites and suggests that these kinds of deposits are turbidites these observations also suggest that the term megaturbidite is appropriated for these deposits the sedimentary analysis indicates that the deposit results from a single event the volume of sediment involved in the process as well as the quartz grain orientation indicating flow motion in the opposite direction of the initial flow and the antidune like structure suggest the formation of reflected flows and the formation of standing waves over the complete water column in the basque flysch sub basins corresponding to a seiche effect the origin of the megaturbidite is probably an earthquake generated collapse on the carbonate platform this example allows providing a new conceptual model for the process of homogenite deposition this model explains the deposition of thick fine grained crudely graded megaturbidites

a unique 4000 year long geological record of multiple tsunami inundations in the augusta bay eastern sicily italy abstract we present the geological evidence for a 4000 year long record of multiple tsunami inundations along the coast of the augusta bay eastern sicily and discuss its implications the research was carried out through a multi theme approach which benefited from an extraordinarily long historical record that we used to guide detailed geomorphologic and geologic surveys coring campaigns and laboratory analyses two sites named the augusta hospital and priolo reserve were selected and investigated in detail along the 25 km long coastline of augusta bay we found evidence for six possibly seven tsunami deposits three of them may be tentatively associated with the 1693 and 365 ad ionian sea historical tsunamis and the 3600 bp santorini event the other three possibly four deposits are evidence for unknown paleo inundations dated at about 650 770 ad 600 400 bc and 975 800 bc at augusta hospital site and 800 600 bc at priolo reserve site we use these ages to extend further back the historical record of tsunamis available for this coastal area the exceptional number of tsunami deposits found with this study allowed us to derive an average geologic tsunami recurrence interval in the augusta bay of about 600 years for the past 4 ka conversely the historical tsunami data for the past millennium suggest an average tsunami recurrence interval of about 250 years this difference in the average recurrence intervals suggests that only the strongest inundations may leave recognizable geological signatures at the investigated sites i e the evidence for the 1908 and 1169 tsunamis is missing but also that the geomorphological setting of the site and its erosional depositional history are critical aspects for the data recording thus an average recurrence interval derived from the geological record should be considered as a minimum figure the identification and age estimation of tsunami deposits represent a new and independent contribution to tsunami scenarios and modeling for coastal hazard assessment in civil protection applications furthermore our study cases provide new elements on tsunami deposit recognition related to exceptionally large events that occurred in the aegean sea

glaciochemistry of polar ice cores a review human activities have already modified the chemical composition of the natural atmosphere even in very remote regions of the world the study of chemical parameters stored in solid precipitation and accumulated on polar ice sheets over the last several hundred thousand years provides a unique tool for obtaining information on the composition of the preindustrial atmosphere and its natural variability over the past this paper deals with the chemistry of polar ice focused on the soluble mineral na nh4 k ca mg h f cl no3 so4 and h2o2 and organic methanesulfonate ch3so3 formate hcoo acetate ch3coo and formaldehyde hcho species and their interpretation in terms of past atmospheric composition aerosols and water soluble gaseous species we discuss ice core dating the difficulties connected with trace measurements and the significance of the ionic composition of snow we examine temporal from the last decades back to the last climatic cycle and spatial including examples from coastal as well as central areas of greenland and antarctica variations in the ionic budget of the precipitation and evaluate ice core studies in terms of the chemical composition of our past atmosphere we review 1 how greenland and antarctic ice cores that span the last few centuries have provided information on the impact of human activities and 2 how the chemistry of deep ice cores provides information on various past natural phenomena such as climatic variations glacial interglacial changes el nino volcanic eruptions and large boreal forest fires

lonestones as indicators of tsunami deposits in deep sea sedimentary rocks of the miocene morozaki group central japan abstract lonestones are isolated larger clasts enclosed in muddy fine grained deposits and are usually interpreted as iceberg rafted dropstones this interpretation implies the existence of glaciers continental ice sheets and consequently a cool climate however alternative interpretations are possible as lonestones may also be deposited by non glacial processes therefore clarification of the depositional processes associated with lonestones is fundamental for studies based on lonestone bearing deposits a field survey of lonestone bearing deposits from early miocene deep sea sedimentary rocks found around the chita peninsula of central japan suggests that tsunami induced flows on the sea bottom may also form lonestones these lonestones are associated with sandy to gravelly deposits and were deposited by high energy episodic currents the main features of these deposits are the multiple stacking of normally graded units and the laterally discontinuous distribution of coarse grained clastic material sands and gravels such features are consistent with deposition by tsunamis and suggest that lonestone bearing depositional successions must be carefully interpreted especially where lonestones are used as glacial indicators as some lonestones were probably put in place by ancient tsunami events

depositional processes of uniform mud deposits unifites hedberg basin northwest gulf of mexico new perspectives structureless mud deposits unifites are a common depositional phenomenon in the intraslope basins of the continental slope of the northwest gulf of mexico high resolution acoustic data and long sediment cores from hedberg basin middle slope were used to provide a better insight into the origin of these enigmatic depositional units the unifite occurring in hedberg basin is structureless under visual observations but x ray radiographs reveal that it consists of three divisions 1 u1 division representing waning sequences of fine grained mud turbidites 2 u2 division characterized by faint normally graded mud layers with occasionally wispy silty interlaminae and 3 u3 division characterized by a uniform appearance with no obvious sedimentological structures other than a faint banding of slightly siltier and slightly more clayey layers high resolution geophysical data reveal that there is no connection between intrabasinal sediment failures and the occurrence of unifites we suggest that unifites have resulted from the deposition of a long lasting 1 53 months pulsating showing internal surges fine grained turbidity current dated at 28 629 ka that originated from the flow transformation of a series of massive sediment failures on the shelf edge and or upper continental slope the fine grained nature of the turbidity current is probably caused by the depositional segregation of the flow by depositing its coarsest material in intraslope basins in more proximal locations we propose that the uniform texture of the unifite is attributed to the development of a stratification interface lower stratified layer generated by the continuous introduction of a turbulent sediment cloud in the intraslope basins the lowest two unifite divisions are considered to develop prior to and during the development of the stratified layer

greenland ice core signal characteristics an expanded view of climate change the last millenium of earth history is of particular interest because it documents the environmental complexities of both natural variability and anthropogenic activity we have analyzed the major ions contained in the greenland ice sheet project 2 gisp 2 ice core from the present to 674 a d to yield an environmental reconstruction for this period that includes a description of nitrogen and sulfur cycling volcanic emissions sea salt and terrestrial influences we have adapted and extended mathematical procedures for extracting sporadic e g volcanic events secular trends and periodicities found in the data sets finally by not assuming that periodic components signals were stationary and by utilizing evolutionary spectral analysis we were able to reveal periodic processes in the climate system which change in frequency turn on and turn off with other climate transitions such as that between the little ice age and the medieval warm period

an ice core proxy for antarctic circumpolar zonal wind intensity using us national centers for environmental prediction us national center for atmospheric research re analysis data we investigate the relationships between crustal ion nssca 2 concentrations from three west antarctic ice cores namely siple dome sd itase00 1 it001 and itase01 5 it015 and primary components of the climate system namely air pressure geopotential height zonal u and meridional v wind strength linear correlation analyses between nssca 2 concentrations and both air pressure and wind fields for the period of overlap between records indicate that the sd nssca 2 variation is positively correlated with spring circumpolar zonal wind while it001 nssca 2 has a positive correlation with circumpolar zonal wind throughout the year r 0 3 p 0 01 intensified southern westerlies circulation is conducive to transport of more crustal aerosols to both sites further correlation analyses between nssca 2 concentrations from sd and it001 and atmospheric circulation suggest that the high inland plateau represented by core it001 is largely influenced by transport from the upper troposphere it015 nssca 2 is negatively correlated with westerly wind in october and november suggesting that stronger westerly circulation may weaken the transport of crustal species to it015 correlations of nssca 2 from the three ice cores with the antarctic oscillation index are consistent with results developed from the wind field investigation in addition calibration between nssca 2 concentration and the multivariate el nino southern oscillation enso index shows that crustal species transport to it001 is enhanced during strong enso events

late holocene marine productivity changes in northern patagonia chile inferred from a multi proxy analysis of jacaf channel sediments abstract a multi proxy approach based on organic organic carbon alkenones and c n and inorganic geochemical proxies biogenic opal inorganic carbon fe ti and ca preserved in the sediments of the jacaf channel cf7 pc33 44 21 s 72 58 w 510 m water depth chilean fjords yields evidence of major past productivity fluctuations in accordance with climatic changes over the last 1800 years the downcore record clearly shows two productivity climate modes the first period prior to 900 cal yr bp is characterized by decreased marine productivity and a reduced continental signal pointing to diminished precipitation and runoff in contrast the second period between 750 cal yr bp and the late 1800s top of core is illustrated by elevated productivity and an increased continental signal suggesting higher precipitation and runoff both time intervals are separated by a relatively abrupt transition of 150 years which roughly coincides with the beginning of the little ice age the increased content of freshwater diatoms and chrysophyte cysts that characterize the last 200 years of the latter mode coincides with a significant decrease in the carbonate content of the sediment together they further indicate increased terrigenous contributions and decreased marine carbonate productivity at the end of the little ice age the correspondence between our record and other paleoclimate studies carried out in south america and antarctica demonstrates that the chilean fjord area of northern patagonia is not just sensitive to local climatic variability but also to regional and possibly global variability

depositional models for fine grained sediment in the western hellenic trench eastern mediterranean sediment in tectonically active topographically restricted settings of the western hellenic arc eastern mediterranean consists primarily of clayey silt and silty clay failure of metastable sediment temporarily stored on relatively steep slopes is triggered by earthquake tremors and eustatic oscillations redeposition of these materials by gravitative transport has resulted in markedly different lithofacies from site to site most piston cores include three late quaternary stratigraphic units that can be correlated with sections in other parts of the eastern mediterranean numerous radiocarbon age determinations enhance the correlation seven fine grained sediment types are identified in cores from eight distinct depositional environments some muds are closely related to specific environments slump and debris flow deposits on slope and high relief environments or to time well laminated mud during the latest pleistocene mid holocene or to both uniform and faintly laminated muds restricted to trench basins turbiditic and hemipelagic muds are common throughout the study area mud distribution patterns correlate closely with calculated sedimentation rates we propose two depositional models for these sediments the first emphasizes downslope transformations resulting in progressively reduced flow concentration during transport from slump and debris flow turbidity current low density turbidity current or turbid layer mechanisms the distal end member deposits settling from low concentration flows are thick rapidly emplaced fine grained uniform muds closely associated with faintly laminated muds these were ponded in flat trench basin plains planktonic and terrigenous fractions in the turbiditic finely laminated and uniform muds record mixing of materials of gravitative and suspension origin during redeposition this sequence prevails under conditions of minimal stratification of water masses as characterized by the present mediterranean in the second model developed for conditions of well developed water mass stratification well laminated rather than uniform mud prevails as the end product of low concentration flows these very finely laminated and graded muds record particle by particle settling from detached turbid layers concentrated along density interfaces they include material from turbid layers complemented by the normal rain of pelagic material stratification barriers resulted in region wide distribution of such deposits in both slope and trench environments

a possible tsunami deposit around the jurassic cretaceous boundary in the boulonnais area northern france abstract an unusual succession of facies locally deposited around the jurassic cretaceous boundary in the boulonnais northern france is attributed to a tsunami event by comparison with recent tsunami deposits this sedimentary succession includes basal erosion with reworked lithified blocks soft sediment deformations an erosional conglomerate overlain by wood fragments and clays containing continental and marine fossils in one setting and conglomerate with mixed fauna in an other setting the tsunami probably affected the coast of the boulonnais area of the london brabant massif the origin of the event is unknown it was most probably triggered by an earthquake but other origins such as volcanic eruptions a giant landslide or even the impact of an extraterrestrial bolide into the ocean may also be considered

solar forcing of the polar atmosphere we present highly resolved annually dated calibrated proxies for atmospheric circulation from several antarctic ice cores itase international trans antarctic scientific expedition siple dome law dome that reveal decadal scale associations with a south pole ice core 10 be proxy for solar variability over the last 600 years and annual scale associations with solar variability since ad 1720 we show that increased decreased solar irradiance is associated with increased decreased zonal wind strength near the edge of the antarctic polar vortex the association is particularly strong in the indian and pacific oceans and as such may contribute to understanding climate forcing that controls drought in australia and other southern hemisphere climate events we also include evidence suggestive of solar forcing of atmospheric circulation near the edge of the arctic polar vortex based on ice core records from mount logan yukon territory canada and both central and south green land as enticement for future investigations our identification of solar forcing of the polar atmosphere and its impact on lower latitudes offers a mechanism for better understanding modern climate variability and potentially the initiation of abrupt climate change events that operate on decadal and faster scales

effects of the santorini thera eruption on manganese behavior in holocene sediments of the eastern mediterranean the explosive eruption on the island of santorini in 1630 b c in minoan times had a large environmental impact over the eastern mediterranean region it has even been suggested that the mn enriched layer the marker bed above the most recent sapropel s1 in sediments of a crestal area of the mediterranean ridge gained mn from a hydrothermal source related to the santorini eruption radiocarbon dating of two cores from this area sampled at high resolution demonstrate that this large mn peak in fact pre dates the santorini event by 2 8 ky and forms part of a pattern seen in mn profiles from all over the eastern mediterranean this same mn profile shape is altered in areas that experienced substantial deposits of either the tephra layer emitted by the santorini eruption or the turbidites that were triggered by it evidence of both of these perturbations is readily identified from compositional element al and sr ca profiles that are distinct from those of the enclosing sediments in one core with a 37 cm thick santorini ash layer an oxidation front succeeded in penetrating the whole ash layer after emplacement to form a mn peak but is now retreating in cores where thin 15 cm santorini turbidites or ash layers lie above s1 oxidation fronts initially form additional mn peaks on top of the turbidites and subsequently alter the characteristic double peaked mn profile shape usually observed above sapropel s1

a thick holocene homogenite from the ionian abyssal plain eastern mediterranean abstract a homogenite layer thicker than 12 m holocene in age occurs in the ionian abyssal plain the graded sandy base is 1 3 m thick most of the layer is structureless and homogeneous in grain size and mineral composition the most remarkable components are siltsized grains composed of aragonite needles they are interpreted as skeleton fragments of the green alga halimeda sp the homogenite covers an area of at least 1100 km 2 and assuming a minimum thickness of 10 m comprises a volume of 11 km 3 the source of the material of the homogenite is a matter of speculation very likely it has been remobilized from different areas around the ionian abyssal plain as triggering event a tsunami generated by the collapse of the santorini caldera about 3500 yrs b p is assumed

stratigraphy of the western mediterranean and southern calabrian ridges eastern mediterranean abstract the present paper illustrates the stratigraphic results of a transponder navigated coring program carried out in 1978 on the southern calabrian ridge cobblestone area 4 and western mediterranean ridge cobblestone area 3 semi quantitative investigations of over 600 foraminiferal samples and 450 nannofossil slides from forty cores with a total recovery of 333 m comprise the data base of the study most of the sediments recovered are late pleistocene or holocene in age the high resolution nannofossil biostratigraphic scheme recently proposed for the quaternary coupled with sapropel stratigraphy and with tephrachronology resulted in precise correlation of the cores mid pleistocene sediments were recovered in a single core from area 4 and in one core from area 3 both located on basin walls four cores from basin walls in area 4 yielded pliocene sediments no sediments older than approximately 3 m y foraminiferal zone m pl 4 reticulofenestra pseudoumbilica nannofossil zone are exposed on the explored walls from the southern calabrian ridge early and late pliocene sediments were recovered from the walls of the deepest crater like basin explored in area 3 but only in dredges in this latter area also two peculiar lithologies were cored basically unfossiliferous but thought to be pre pliocene in age a mud breccia whose clasts yield a sparse assemblage of mid cretaceous planktonic foraminifera and a dolomitic mudstone which is attributed to the late messinian on the basis of correlation with a similar lithology cored at dsdp site 374 and substantiated by analogy in x ray controlled mineralogical composition the fairly complete record of late pleistocene and holocene sapropels recovered in the southern calabrian ridge discards the hypothesis that the southern part of the ionian sea did not undergo stagnant cycles during the ice ages another hypothesis relating the origin of cobblestone topography to olistostromes is also considered untenable on the basis of the new data the large number of cores precisely located on a previously mapped highly irregular bottom physiography disproves that large scale chaotic sedimentation occurred debris flows recorded in base of slope cores document local slope failures

untangling the complex origin of turbidite activity on the calabrian arc ionian sea over the last 60ka abstract the ionian sea due to the presence of two accretionary prisms the calabrian arc and the mediterranean ridge associated with the subduction of the nubia plate and the eurasia plate is the witness of large and catastrophic turbidite events these events are associated with high magnitude earthquakes and tsunamis they lead an important gravity driven sedimentary deposit in the ionian basin in this study we analysed turbidite deposits in order to establish a calendar of the palaeoseismicity and volcaniclastic events from etna on the calabrian arc two gravity cores collected in a slope basin on the calabrian arc and in the ionian abyssal plain record more than two hundred turbidites over the last 60 000 years these turbidites were dated with a multi proxy approach radiometric dating tephrochronology and sapropels the origin of the turbidites was studied with a sedimentary approach grain size lithology thin section and geochemistry of volcanic glass the results suggest that three triggers are responsible for the deposits of turbidites there are siliciclastic turbidites triggered by earthquakes and tsunamis waves and volcaniclastic turbidites triggered by the etna volcano eruptions or flank collapses co seismic turbidites present different recurrence times depending on the location of the core on the calabrian arc recurrence times vary between 450 and 1000 years according to the periods in time on the abyssal plain recurrence times are shorter and more regular around every 240 years

bipolar changes in atmospheric circulation during the little ice age annually dated ice cores from siple dome west antarctica and central greenland indicate that meridional atmospheric circulation intensity increased in the polar south pacific and north atlantic at the beginning 1400 a d of the most recent holocene rapid climate change event the little ice age lia as deduced from chemical concentrations at these core sites the lia was characterized by substantial meridional circulation strength variability and this variability persists today despite strong evidence for an end to lia cooling thus increased late 20th century storm variability may be in part a result of the continuation of these climatic fluctuations

possible tsunami signatures from an integrated study in the augusta bay offshore eastern sicily italy abstract twelve anomalous layers marked by a high concentration of displaced epiphytic foraminifera species growing in vegetated substrates like the posidonia oceanica and subtle grain size changes were found in a 6 7 m long fine sediment core ms 06 sampled 2 km off the shore of the augusta harbor eastern sicily at a depth of 72 m recording the past 4500 yrs of deposition because concentrations of epiphytic foraminifera are quite common in infralittoral zones but not expected at 72 m we believe that these anomalous layers might be related to the occurrence of tsunamis causing substantial uprooting and seaward displacement of p oceanica blades with their benthic biota our approach involved the study of geophysical data morphobathymetry seismic reflection and seafloor reflectivity and sediment samples including x ray imaging physical properties isotopic dating tephrochronology grain size and micropaleontology correlations between anomalous layers and tsunami events have been supported by a multivariate analysis on benthic foraminifera assemblage and dates of historical tsunami records we found that four out of the eleven layers were embedded in age intervals encompassing the dates of major tsunamis that hit eastern sicily 1908 1693 and 1169 and the broader eastern mediterranean santorini at about bp 3600 one more layer even if less distinct than the others was also defined and may be the evidence for the ad 365 crete tsunami

the augias megaturbidite in the central ionian sea central mediterranean and its relation to the holocene santorini event abstract a thick mud turbidite up to 24 m in thickness termed the augias turbidite is decribed from the ionian and sirte abyssal plains and the adjacent slopes of the calabrian rise and the mediterranean ridge the material of the megaturbidite is derived from the gulf of sirte revealed by its high aragonite content and through erosion from the sirte rise the shallow water sediments making up the turbidite were probably mobilized by a tsunami caused by the minoan santorini collapse around 3500 yr b p the volume of the mobilized sediments is calculated as a minimum of 65 km3 isolated turbidites of the same age deposited on the upper slope of the mediterranean ridge may consist of tsunami mobilized shallow water material as well as of earthquake triggered sediment from the flanks of local depressions

deep sea tsunami deposits in the eastern mediterranean new evidence and depositional models the tsunami wave induced by the collapse of the santorini caldera after the bronze age minoan eruption 3500 bp produced turbidites and large volume mega turbidites in the abyssal plains of the ionian sea as well as on the floor of small basins of the mediterranean and calabrian ridges characterized by the so called cobblestone topography since the first discovery in 1978 a holocene mud layer which has been termed homogenite and which typically shows a graded interval at its base has been identified and correlated in over 50 deep sea cores recovered in the eastern mediterranean four types of homogenite can be distinguished each related to a particular depositional setting 1 a closed cobblestone these are from a few decimetres to several metres thick pelagic turbidites of local provenance exclusively found at the bottom of small sized ponded basins of the mediterranean and calabrian ridges a debris flow may be present at the base of the turbidite where the vertical relief of the basins is over 200 m 2 b abyssal plain a 10 to 20 m thick megaturbidite recorded in the ionian and sirte abyssal plains the source area is the african continental margin possibly the continental shelf it can be easily identified as a transparent acoustic layer that shows recent deformation across the deformation front of the mediterranean ridge accretionary prism the volume of the minoan homogenite in the ionian abyssal plain has been calculated at a minimum of 11 km3 3 c open cobblestone this type is exclusively found on the outer slope of the mediterranean ridge near the deformation front unlike types a and b the base of the turbidite here is erosional instead of depositional this homogenite has been deposited in small basins and occasionally on topographic highs of the mediterranean ridge by the up slope flow of turbidity currents of african provenance that formed the abyssal plain deposit type b 4 d a fourth depositional model has been identified homogenites present in deep anoxic basins of the mediterranean ridge this setting is substantially similar to type a but the vertical relief of the basin is much higher up to 800 m and the deposition occurs in high density anoxic brines which modify the settling rate and hence the resulting sedimentological characters

tsunami induced sediment transport in the abyssal mediterranean sea an unusual stratigraphic unit nicknamed homogenite fills topographic lows in the complex ridge and trough bathymetry at two survey sites on the western mediterranean ridge and the calabrian ridge on near bottom 4 khz seismic reflection profiles this unit us an acoustically transparent near surface flat lying layer whereas in cores it is a homogeneous gray marl as much as 7 m thick grain size decreases upcore within the unit implying that it was deposited in a single event controlled by gravitational settling the stratigraphic position of the homogenite relative to a firmly dated sapropel bed suggests emplacement between 4400 and 3100 yr b p the source of the homogenite is inferred to be the nearby basin walls farther east two other sites with similar rugged topography lack homogenite entirely a triggering mechanism is required which is capable of initiating massive sediment transport simultaneously in many separate basins at the western two survey sites but which is not effective at the eastern sites a large archeologically recorded earthquake of the correct age is considered and rejected because its epicenter is closer to the nonhomogenite bearing sites than to the sites where this sediment type was observed and because several other earthquakes of comparable magnitude have since been recorded in the area whereas the homogenite is unique the 3 500 yr b p collapse of the caldera of the volcano of santorini caused a huge tsunami which is recorded archeologically and geologically around the eastern mediterranean because of refraction of the tsunami by the bathymetry and because the caldera collapsed in its southwest corner a disproportionate amount of tsunami energy was directed toward the western area where homogenite is observed in contrast the homogenite free sites were relatively sheltered an order of magnitude calculation shows that the near bottom oscillating currents accompanying the santorini tsunami were at or above the threshold erosion velocity at the homogenite bearing sites in addition the near bottom pressure pulse under the tsunami at the homogenite bearing sites was sufficient to cause liquefaction of sediments neither mechanism was adequate to cause sediment transport or slope failure at the homogenite free sites

historical and pre historical tsunamis in the mediterranean and its connected seas geological signatures generation mechanisms and coastal impacts abstract the origin of tsunamis in the mediterranean region and its connected seas including the marmara sea the black sea and the sw iberian margin in the ne atlantic ocean is reviewed within the geological and seismotectonic settings of the region a variety of historical documentary sources combined with evidence from onshore and offshore geological signatures geomorphological imprints observations from selected coastal archeological sites as well as instrumental records eyewitnesses accounts and pictorial material clearly indicate that tsunami sources both seismic and non seismic e g volcanism landslides can be found in all the seas of the region with a variable tsunamigenic potential local regional and basin wide tsunamis have been documented an improved map of 22 main tsunamigenic zones and their relative potential for tsunami generation is presented from west to east the most important tsunamigenic zones are situated offshore sw iberia in the north algerian margin in the tyrrhenian calabria and messina straits in the western and eastern segments of the hellenic arc in the corinth gulf of central greece in the levantine sea offshore the dead sea transform fault and in the eastern side of the marmara sea important historical examples including destructive tsunamis associated with large earthquakes are presented the mean recurrence of strong tsunamis in the several basins varies greatly but the highest event frequency 1 96 years is observed in the east mediterranean basin for most of the historical events it is still unclear which was the causative seismic source and if the tsunami was caused by co seismic slip by earthquake triggered submarine landslides or by a combination of both mechanisms in pre historical times submarine volcanic eruptions i e caldera collapse massive pyroclastic flows volcanogenic landslides and large submarine landslides caused important tsunamis although little is known about their source mechanisms we conclude that further investigation of the tsunami generation mechanisms is of primary importance in the mediterranean region inputs from tsunami numerical modeling as well as from empirical discrimination criteria for characterizing tsunami sources have been proved particularly effective for recent well documented aseismic landslide tsunamis e g 1963 corinth gulf 1979 cote d azur 1999 izmit bay 2002 stromboli volcano since the tsunami generation mechanisms are controlled by a variety of factors and given that the knowledge of past tsunami activity is the cornerstone for undertaking tsunami risk mitigation action future interdisciplinary research efforts on past tsunamis are needed

deep sea tsunami deposits triggered by the explosion of santorini 3500 y bp eastern mediterranean abstract the collapse of the santorini caldera after the catastrophic eruption of the bronze age 3500 y bp caused a tsunami wave that had catastrophic effects in the ionian basin including its deepest parts pelagic turbidites of local origin were deposited on the bottom of small perched basins of the southern calabrian western and central mediterranean ridges type a homogenite whereas a megaturbidite of distal origin presumably triggered by the tsunami wave hitting the shoreline of the sirte gulf was deposited on the ionian and sirte abyssal plains extending eastwards as far as the western herodotous trough depositing a thick acoustically transparent layer type b homogenite three core transects crossing the deformation front of the mediterranean ridge are presented and discussed a fourth transect of giant piston cores was collected on the abyssal plains located to the south of the mediterranean ridge all those to the west of the collision zone contain the holocene homogenite with a thickness in excess of 20 m whereas the cores taken from the herodotous abyssal plain east of the collision zone are devoid of the homogenite sedimentological analyses were performed on the only giant core that penetrated the sandy base of the homogenite and the underlying pelagic sediments of late pleistocene last glacial age the african provenance of this typical type b homogenite is corroborated by shallow water fauna derived from the north african shelf no sedimentological characteristics peculiar to tsunamiites are observed in the deep sea homogenite of the eastern mediterranean

high precision dating of volcanic events a d 1301 1995 using ice cores from law dome antarctica a record of volcanic activity over the period a d 1301 1995 has been extracted from three law dome ice cores east antarctica the record dating is unambiguous at the annual level from a d 1807 to 1995 and has an uncertainty of 1 year at a d 1301 signals from 20 eruptions are preserved in the record including those of two unknown eruptions with acid deposition beginning in a d 1810 8 and a d 1685 8 the beginning of the ice core signal from the a d 1815 tambora eruption is observed in the austral summer of a d 1816 1817 the mean observed stratospheric transport and deposition time to law dome from the eruption site is 1 5 years 0 6 years from 11 well dated eruptions the largest eruption observed in the law dome record has its maximum in a d 1460 with volcanic sulfate deposition beginning in the austral winter of a d 1459 this event is also observed in other ice core records and is attributed to the volcano kuwae with an eruption date in the range a d 1455 9 1459 9 if all sources of error are considered this is at least three years later than the date previously ascribed by dendrochronological and historical studies

submarine evidence of a debris avalanche deposit on the eastern slope of santorini volcano greece abstract hummocky seafloor features were discovered on the eastern flank of santorini volcano greece multibeam bathymetric mapping airgun seismic profiling side scan sonar survey and remotely operated vehicle rov dives have been carried out to characterize the nature of the hummocks these hummocks appear to be composed of several tens of blocks that are up to several hundred meters in diameter and are the surface expression of a much larger deposit than is observed in the bathymetry the sidescan and airgun data show that the deposit covers an area of approximately 6 km wide by 20 km long and is up to 75 m thick we estimate the total volume of the deposit to be approximately 4 4 10 9 m 3 sampling of these blocks show they are composed of pyroclastic flow deposits produced during the minoan eruption of santorini ca 3600 bp we propose that the deposit is the result of a multi stage landslide event that was caused by one of the several large earthquakes or volcanic eruptions that have occurred in the vicinity of santorini since the minoan eruption one or more of these events likely triggered the destabilization of a part of the eastern flank of santorini which led to a debris avalanche depositing blocks and forming a hummocky terrain at the base of the island s slope the mass movement later evolved into a turbulent suspension flow that traveled 20 km or more from the presumed initial failure given the size of the landslide deposit it might have a tsunami potentially affecting the islands across the southern aegean sea the understanding of earthquake landslide dynamics has important implications for hazard assessment in this seismically active historical and highly populated region of the world

reconstruction of the holocene seismotectonic activity of the southern andes from seismites recorded in lago icalma chile 39 s abstract south central chile is one of the most geodynamically active areas in the world characterized by frequent volcanic eruptions and numerous earthquakes which are both recorded in lake sediments in lago icalma 39 s long piston and short gravity coring as well as 3 5 khz high resolution seismic profiling have been carried out in order to study the holocene sedimentary infill of the lake with a special focus on earthquake triggered deposits macroscopic description of sediment cores and detailed grain size analyses allow us to identify four types of seismically induced deposits or seismites slump deposits chaotic deposits turbidites s s and homogenites homogenites are characterized by the occurrence of three distinct units on grain size profiles i e a coarse base a thick homogeneous unit topped by a thin layer of very fine sediment and by the typical distribution of the grain size parameters in a skewness sorting diagram while turbidites s s are characterized by a continuous fining upward trend radiocarbon 210pb dating and tephrochronology allow us to demonstrate that the regional seismotectonic activity was probably very high between 2200 and 3000 cal years bp as well as between 7000 and 8000 cal years bp and that none of the historically documented earthquakes has triggered a seismite in lago icalma the most recent seismite recognized in the sediments of lago icalma is a slump deposit dated at 1100 100 ad i e older than the period covered by historical records the remarkable record of seismites between 2200 and 3000 cal years bp is probably influenced by a major eruption of sollipulli volcano at 3000 cal years bp which has rejuvenated the stock of terrigenous particles available for erosion by depositing a thick layer of pumices all over the watershed of lago icalma and by clearing the vegetation covering the volcanic ash soils this paper demonstrates that the record of seismically triggered deposits in lake sediments is not only controlled by the intensity of the triggering earthquake and the occurrence of unstable sediment along the lake slopes but also by the presence of particles available for erosion remobilisation in the watershed

megaturbidite deposits in the holocene basin fill of lake como southern alps italy abstract for the first time limnogeological investigations have been carried out in lake como the deepest lake of the alps combining a bathymetric survey multibeam simrad 3000 with a high resolution seismic reflection study single channel 3 5 khz sub bottom profiler and a coring campaign gravity corer this data set enables detailed characterization of the sedimentary subsurface in the western branch of the lake the como branch which has a typical fjord morphology this paper focuses on the deepest part of the como branch argegno basin in which up to 3 5 m thick turbidite deposits are identified the basin fill of the como branch is characterized by well layered draping and onlapping pelagic sediments that are locally affected by creeping and that are intercalated with mass wasting deposits in particular with two large debris flow deposits evolving into megaturbidites in the deepest part of the basin the multibeam data together with the acoustic facies distributions and the volumes of these two major sedimentary deposits mt1 3 106 m3 and mt2 10 5 106 m3 indicate that they resulted from large slides at the northern tip of the como branch along the steep slopes of a sub lacustrine plateau the estimated ages of these events around the mid 12th mt1 and early 6th mt2 centuries are extrapolated from mean sedimentation rates based on radiocarbon 14c and radionuclide 137cs analyses from short cores in the argegno basin possible trigger mechanisms leading to these catastrophic events in the como branch include a combination of steep slope overloading with significant lake level fluctuations related to holocene climate change and or earthquake shaking the tentative age assignment places the age of both major mass movements near two other events mt1 near the occurrence of a major earthquake in the po plain in 1222 ad intensity ix mcs macroseismically derived magnitude 6 2 and mt2 near a megaturbidite triggered in 700 ad in a proglacial lake in southeastern switzerland blass a anselmetti f grosjean m sturm m 2005 the last 1300 years of environmental history in the sediments of lake sils engadine switzerland eclogae geologicae helvetiae 98 319 332 since dangerous tsunami like waves seiches can be generated by large sub aqueous landslides leading to such megaturbidites in this fjord like basin future studies are required 1 to constrain the age of these catastrophic events 2 to document the stabilities of the steep slopes in the como branch 3 to assess the expected frequency of such catastrophic events and 4 to model the propagation of large waves in the como branch and their potential damage along the highly populated lake shore

a note on the preservation of offshore tsunami deposits abstract in this contribution we explore the preservation potential of offshore tsunami deposits the application of linear wave theory and flat bottom conditions allows a simplified representation of the physical environment in such an environment it is possible to compute the boundary water depth below which the influence of storm waves on tsunami deposits is negligible the majority of the tsunami deposits described in the literature were deposited onshore where the tsunami wave is transformed into bores and rollers these deposits differ from tsunami sediments of the deeper shelf where the water sediment interaction corresponds more to wave influences we define the boundary depth db as the depth below which tsunami deposits cannot be reworked due to storm waves this is based on the assumption that the wave base coincides with the seabed if the wave base is below the bed a reworking of bed sediments occurs if it is above no energy is transferred to the bottom as an example we use tide gauge records at pointe de la rue seychelles and ca 50 km offshore from brisbane australia at a water depth of 70 m to derive the major wave parameters of the sumatra tsunami and a category 1 cyclone that occurred from 4 6 march 2004 in brisbane the brisbane storm wave reached the maximum wave height of 14 3 m wave periods varied between 6 s and 14 s and the computed maximum wavelength was 237 m the largest height of the sumatra tsunami was 3 01 m periods of between 24 min and 61 min were computed for the time between two subsequent peaks the combination of our hydrodynamic considerations with information from a simplified hjulstrom sundborg diagram implies that the most powerful storm and tsunami waves produce conditions near and at the sea bed that allow the transport of sediment grains from decimeters to meters in diameter that means a sandy tsunami deposit in the area of the brisbane tide gauge would be reworked by storm waves assuming the highest wave amplitude during the 2004 march storm at brisbane as such a boundary wave the water depth below which preservation of tsunami deposits is most likely is greater than 65 m

tephrostratigraphy and tephrochronology in the philippi peat basin macedonia northern hellas greece abstract three tephra layers have been identified in the upper 15 m of a 190 m section of peat beneath the philippi fen they provide significant lithological and chronological markers throughout the fen and the aegean region the upper tephra pht1 consists of shards of a transparent calcalkaline felsic glass and fragments of plagioclase augite hypersthene and rare hornblende magnetite apatite and quartz peat directly beneath pht1 gave a radiocarbon approximate age of 13 000 yr the middle tephra layer pht2 which resembles pht1 in chemistry and petrography but contains more crystals and lithic fragments rests on peat dated ca 18 000 14 c yr bp the lower tephra pht3 has colorless to brown glass shards with a trachytic chemistry and a mineral assemblage of sanidine sodic plagioclase biotite aegirine augite hornblende titanite and apatite bracketing radiocarbon ages imply that pht3 accumulated about 30 000 14 c yr bp the likely ages of pht1 and pht2 together with their mineralogical and chemical characteristics suggest that these tephras came from the volcanic field of thera in the hellenic arc pht2 particularly was derived from a major known explosive eruption ca 18 000 yr bp the cape riva eruption correlative to the y 2 tephra layer evidence for pht3 suggests derivation from the campanian province of italy and correlation with the campanian ignimbrite and the y 5 ash beneath the mediterranean sea

sedimentary characteristics and depositional models of two types of homogenites in an eocene continental lake basin shulu sag eastern china abstract homogenites are homogeneous and structureless fine grained rocks they have been studied extensively in marine settings and are typically interpreted as being related to catastrophic events such as earthquakes however studies on lacustrine homogenite like rocks are limited new core data from the shulu sag in china reveal that thick massive calcilutites exist in the lower shahejie 3 formation which formed during the middle eocene rifting stage based on petrographic geochemical and mineralogical data these massive calcilutites are interpreted as homogenites and grouped into two types type a homogenite is composed of intrabasinal materials characterized by high calcite total organic carbon toc content and 13c value type a homogenite has two facies successions the first of which is characterized by homogeneous appearance capped by an erosional interface and the second is characterized by repeated massive laminated calcilutite successions type b homogenite contains abundant allochthonous materials displaying relatively high dolomite content and low calcite toc and 13c content type b homogenite represents the topmost finer portion of a graded megabed which includes from base to top grain supported carbonate conglomerates slumped deformed portions and debrites the whole unit can be considered as a megaturbidite earthquakes are the most reasonable triggers of homogenite formation in the shulu sag type a homogenites are thought to be derived by fluidification resuspension and decantation of lacustrine fines due to shock waves generated by an earthquake type b homogenites might be deposits of distal turbidity currents and turbid clouds transformed from other gravity flows the results of this study provide a better understanding of the formation of homogenites caused by earthquakes in a confined lacustrine basin

a 700 year record of atmospheric circulation developed from the law dome ice core east antarctica 1 a 700 year high resolution multivariate ice core record from dome summit south dss 66 46 s 112 48 e 1370 m law dome is used to investigate sea level pressure slp variability in the region of east antarctica empirical orthogonal function eof analysis reveals that the first eof ldeof1 of the combined glaciochemical oxygen isotope ratio and accumulation rate record from dss represents most of the variability in sea salt seen in the record ldeof1 is positively correlated at least 95 confidence level to instrumental june mean slp across most of east antarctica over the last 700 years ldeof1 levels at law dome were the highest during the nineteenth century suggesting an increase in intensification of winter circulation during this period the law dome dss oxygen isotope ratio series also indicates that the nineteenth century had the coldest winters of any century in the record in contrast ldeof1 levels were the lowest at law dome during the eighteenth century suggesting a significant shift in the patterns and or intensity of east antarctic atmospheric circulation between the eighteenth and the nineteenth centuries the ldeof1 sea salt record is characterized by significant decadal scale variability with a strong 25 year periodic structure

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

acoustic facies of holocene megaturbidites in the eastern mediterranean abstract the acoustic facies of holocene megaturbidites in the central western abyssal plains of the eastern mediterranean sea is analysed combining core lithology and synthetic seismograms produced on the basis of p wave velocity profiles derived by multi sensor core logging from a core in the western herodotous trough the acoustic facies of the megaturbidite is divided in two layers 1 an upper transparent low velocity layer corresponding to structureless mud 2 a lower highly reflective high velocity layer corresponding to the graded sandy base correlation with sub bottom profiler data allowed us to estimate in about 21 23 m the maximum total thickness of the two layer megaturbidite in the ionian abyssal plain these results demonstrate that thicknesses traditionally computed on the basis of the acoustically transparent layer alone may produce a relevant underestimation of the total volume of the deposit the total volume of the megaturbidite extending over the ionian and sirte abyssal plains including the western herodotous trough is therefore estimated in about 162 10 km 3

sedimentary earthquake records in the izmit gulf sea of marmara turkey abstract sedimentary earthquake records of the last 2400 a including that of the devastating 17 august 1999 izmit earthquake mw 7 4 were studied in cores from the 210 m deep central karamursel basin of the izmit gulf in the eastern sea of marmara using laser grain size physical properties stable o and c isotopes and xrf core scanner analyses and dated by radionuclide and radiocarbon methods the earthquake records are represented by turbidite homogenite mass flow units thu that commonly contain a basal coarse layer a middle laminated silt layer and an overlying homogeneous mud layer the coarse basal part has a sharp and sometimes scoured lower boundary and includes multiple coarse sand silt layers or laminae showing normal size grading multiple coarse layers and occasional bi directional cross bedding suggest deposition from a bed load during water column oscillations or seiche effect the grain size characteristics of the overlaying laminated silt and the homogeneous mud units indicate deposition from weak oscillating currents and homogeneous suspension respectively high mn value just below the base of thus suggests diagenetic enrichment at oxic anoxic redox boundary before the mass flow event sharp decrease in mn with very low values within the thus suggests transient redox conditions following the mass flow variable geochemical compositions of the basal coarse layers indicate different sediment sources for different thus eight sedimentary earthquake records observed in the last 2400 a in the izmit gulf can be confidently correlated with the historical earthquakes of 1999 1509 ad ms 7 2 1296 ad i vii 865 ad i viii 740 ad i viii 268 ad i viii 358 ad i ix and 427 bc this gives an earthquake recurrence time of ca 300 a with the interval between consecutive events ranging from 90 to 695 a

record of volcanism since 7000 b c from the gisp2 greenland ice core and implications for the volcano climate system sulfate concentrations from continuous biyearly sampling of the gisp2 greenland ice core provide a record of potential climate forcing volcanism since 7000 b c although 85 percent of the events recorded over the last 2000 years were matched to documented volcanic eruptions only about 30 percent of the events from 1 to 7000 b c were matched to such events several historic eruptions may have been greater sulfur producers than previously thought there are three times as many events from 5000 to 7000 b c as over the last two millennia with sulfate deposition equal to or up to five times that of the largest known historical eruptions this increased volcanism in the early holocene may have contributed to climatic cooling

sedimentological and geochemical evidence for seismoturbidite generation in the kumburgaz basin sea of marmara implications for earthquake recurrence along the central high segment of the north anatolian fault abstract holocene earthquake history of the central high segment of the north anatolian fault is examined here for the first time based on analysis of seismoturbidites within a 21 m long piston core recovered from the kumburgaz basin in the sea of marmara the visual lithological description combined with detailed grainsize analyses indicate that the deep basin hemipelagic sediments are interrupted by 28 turbidite units during the last 6 1 cal kyrs bp the turbidites show strong segregation and a sharp boundary between a coarse basal part and overlying homogenite as inferred from detailed sedimentological and geochemical data several amalgamated turbidites are recognized by repeated fining upward sequences with no intervening homogenite indicating multiple episodes of traction and deposition as a result of various slope failures and turbidity currents each amalgamated unit was possibly triggered by the same earthquake event rupturing in the sea of marmara the most common sedimentary feature is the continuous parallel lamination that was presumably introduced by long lasting water oscillations on suspended sediments due to the seiche effect the establishment of geochemical criteria and exclusive sedimentary processes distinguish earthquake triggered turbidites seismoturbidites from other trigger factors moreover such distinction allows us to evaluate hydrodynamic sedimentary conditions and processes in the kumburgaz basin the base of most seismoturbidites are associated with a sharp increase in mn concentration that can be explained by a diagenetic enrichment of mn at the oxic anoxic interface of the sediments near the seafloor prior to the deposition of the turbidite an age depth model of the studied core based on seven ams 14c ages allows correlation between historical earthquakes and seismoturbidites in the kumburgaz basin at least the latest nine of them fit well with the previously recorded major earthquake events between ca 500 cal yrs bp and 2 5 cal kyrs bp

low sea level stand emplacement of megaturbidites in the western and eastern mediterranean sea piston cores from the balearic and herodotus abyssal plains in the mediterranean sea show that the late pleistocene to holocene sedimentary sequence is dominated by turbidite muds on each plain one turbidite bed is conspicuous by its thickness and this bed can be correlated basinwide on the basis of geochemical compositional analysis and its apparent correspondence with a distinct acoustically transparent layer on high resolution seismic records these megabeds on the two plains represent megaturbidites of very large volume 300 600 km3 each and are shown by ams radiocarbon dating to have been emplaced during the last low stand of sea level at the height of the last glacial maximum the megabed on the balearic abyssal plain is derived from the southern european margin and is the main sedimentation event over the last 120 ka it emplaced as much material as was deposited by smaller flows during the previous 25 ka sedimentation rate curves for the balearic abyssal plain show that falling sea level correlates with increased terrigenous deposition and that gross sedimentation rates in the basin increased as sea level fell from 120 18 ka due to more frequent emplacement of distal turbidites the herodotus abyssal plain megabed is derived from the libyan egyptian continental shelf west of the nile delta and was the dominant sedimentation event in this basin during the past 60 kyr high resolution seismic profiles from the ionian and sirte abyssal plains in the central mediterranean also suggest possible low sea level emplacement of megabeds in these regions available evidence suggests widespread emplacement of megaturbidites throughout the mediterranean at the last glacial maximum although the triggering mechanisms for these events remain speculative catastrophic destabilisation of the margin after a long period of accumulation with an increased rate of sediment supply is suggested

a 1400 year high resolution record of atmospheric circulation over the north atlantic and asia major ion series developed from new subannual scale sampling of an ice core from central greenland are calibrated with instrumental series of atmospheric sea level pressure recording major marine icelandic low and terrestrial siberian high atmospheric circulation systems to provide proxy records of atmospheric circulation over the past 1400 years examination of the proxy records reveals major changes in behaviour of these systems c ad 1400 multidecadal and centennial scale periodic components characterization of mean sea level pressure anomaly fields during the little ice age and the mediaeval warm period the potential role of solar forcing coupled ocean atmosphere associations and a perspective within which the characteristics of instrumental era climate can be assessed

interpretation of recent southern hemisphere climate change climate variability in the high latitude southern hemisphere sh is dominated by the sh annular mode a large scale pattern of variability characterized by fluctuations in the strength of the circumpolar vortex we present evidence that recent trends in the sh tropospheric circulation can be interpreted as a bias toward the high index polarity of this pattern with stronger westerly flow encircling the polar cap it is argued that the largest and most significant tropospheric trends can be traced to recent trends in the lower stratospheric polar vortex which are due largely to photochemical ozone losses during the summer fall season the trend toward stronger circumpolar flow has contributed substantially to the observed warming over the antarctic peninsula and patagonia and to the cooling over eastern antarctica and the antarctic plateau

florisphaera profunda and the origin and diagenesis of carbonate phases in eastern mediterranean sapropel units high relative concentrations of the lower photic zone nannofossil florisphaera profunda have been reported in all recent eastern mediterranean sapropels in the most recent sapropel s1 high bulk sediment sr ca ratios occur along with high f profunda contents toward the base of the unit exemplified here in four cores from 1 5 3 5 km water depth co occurring biogenic carbonates contain insufficient sr to account for these high sr concentrations and x ray diffraction and selective leaching show that the high sr ca ratios are due to aragonite the caco3 polymorph that is rarely preserved in deep marine sediments with 1 wt sr the possible sources of this aragonite include 1 precipitation with surface ocean production 2 detrital input from shallow water sediments by high continental runoff or 3 postdepositional diagenetic formation driven by increased pore water alkalinity resulting from sulphate reduction the third formation mechanism for the aragonite is favored in which case the similarity in the positions of the aragonite and f profunda abundance maxima in sapropels is probably related to corg accumulation and resulting sulphide diagenesis that produces high pore water alkalinity there is clear micropaleontological evidence that dissolution of the less soluble biogenic low mg caco3 is occurring or has occurred during early diagenesis in these sediments despite the coexistence of the more soluble high mg calcite and aragonite polymorphs similar sr ca maxima are also found associated with older sapropels always located close both to local minima in surface ocean 18o that signal maximum monsoon driven runoff and to maxima in diagenetic sediment sulphide contents high freshwater flows from monsoons are believed to drive eastern mediterranean sapropel formation through water column stabilization that favors f profunda production and later through development of deep water column dysoxia anoxia because of reduced ventilation the relative abundances of f profunda are high between 5 and 11 14c kyr b p with a maximum at 9 14c kyr b p the surface ocean production changes marked by f profunda therefore begin earlier and finish later than the formation of the s1 sapropel which only develops between 6 and 10 14c kyr b p

sediment grains moved by passing tsunami waves tsunami deposits in deep water abstract tsunamis propagating in the open ocean have associated horizontal particle velocities that do not change with depth yet the limiting water depth where a tsunami of given characteristics will initiate sediment motion remains unknown based upon linear wave theory and a parametrization of the shields curve equations are derived and solved using an iterative scheme to address the topic of grain movement by tsunami waves as a function of water depth and wave amplitude the focus is on waves in deep water where tsunami waves behave linearly and on non cohesive sediment grains furthermore the question is addressed of which grain sizes are picked up on a sloping beach as the wave shoals according to the results even the boxing day tsunami in 2004 was incapable of moving fine sand in water deeper than 985 m in the bay of bengal and 335 m in the indian and pacific oceans the results suggest that tectonic tsunamis of size equal to or smaller than the boxing day tsunami cannot initiate motion of deep water cohesionless sediments that can be correlated on an oceanic basin wide scale

seismoturbidites a new group of resedimented deposits abstract turbidite beds of exceptionally large volume and areal extent occur in both modern and ancient deep water basins these beds which may reach individual volumes in excess of 100 km3 are apparently the product of catastrophic gravity flows triggered by earthquakes along the margins of highly mobile basins most commonly elongate flysch troughs turbidite beds produced by these catastrophic events are generally characterized by very distinctive geometry internal structures and composition and are termed herein seismoturbidites characteristically these sediments lack time persistent features of deep sea fans such as channels and lobes seismoturbidites may occur as scattered intercalations diluted within otherwise normal turbidite sequences thus forming generally excellent markers for basin wide correlations or as closely spaced repetitive units comprising the bulk of the sedimentary fill of certain flysch basins in both cases they may offer a tremendously useful tool for a better understanding of the distribution of paleoseismic zones in time and space

tsunami hazard evaluation of the eastern mediterranean historical analysis and selected modeling seismic sea waves in the eastern mediterranean have been reported since written history first emerged several thousand years ago we collected and investigated these ancient and modern reports to understand and model the typical tsunamigenic sources with the ultimate purpose of characterizing tsunami hazard along the levant coasts surprisingly only 35 of the tsunami reports could be traced back to primary sources with the balance remaining questionable the tsunamis varied in size from barely noticeable to greatly damaging and their effects ranged from local to regional overall we list 21 reliably reported tsunamis that occurred since the mid second century b c along the levant coast along with 57 significant historical earthquakes that originated from the local continental dead sea transform dst system an in depth evaluation shows that 10 tsunamis are clearly associated with on land dst earthquakes and therefore as formerly suggested they probably originated from offshore seismogenically induced slumps eight tsunamis arrived from the remote hellenic and cypriot arcs one from italy and two are left with as yet unrecognized sources a major conclusion from this work is that onshore earthquakes commonly produce tsunamis along the levant coastline and that analogous situations are present elsewhere in the mediterranean as well as along the california coast and in another regions with active faults near the coast we modeled three typical scenarios and in light of the sumatra experience we examined the more likely severe magnitudes this of course leads us toward the upper range of expected run ups the models show that sooner than five minutes after a strong earthquake produces an offshore slump which occurs after close to a third of the large dst earthquakes a 4 to 6 m run up may flood part of the syrian lebanese and israeli coasts tsunamis from remote earthquakes however arrive later and produce only 1 to 3 m run ups but are more regional in extent online material tsunami modeling and reports

sedimentological characteristics of the 2015 tropical cyclone pam overwash sediments from vanuatu south pacific abstract the interpretation of sediments deposited by prehistoric tropical cyclones tc s is limited by a lack of modern analogues particularly in the south pacific on 13 march 2015 tc pam made landfall on vanuatu reaching category 5 intensity with 10 minute sustained wind speeds as high as 270 km h three months after landfall we measured flow height terrain elevation plus storm flow depth and inland extent of tc pam s maximum coastal inundation composed of astronomical tides storm surge and superimposed storm waves and described the sedimentological characteristics of the tc pam overwash sediments from trenches and transects at two sites manuro and port resolution bay at manuro a mixed carbonate embayment the maximum flow height was 5 29 m mean sea level msl with an inland extent of 106 m the tc pam sediments transition from a coarse to medium grained mean 1 07 carbonate sand 10 cm thick to pumice 18 cm thick that extends 400 m inland into lake otas the tc pam overwash sediments are characterized by a coarsening upward sequence 1 45 to 0 23 followed by a finer grained eolian cap at port resolution bay a volcaniclastic beach prb the maximum flow height was 3 30 m msl 1 51 m flow depth with an inland extent of 117 m the tc pam overwash sediments transition from a medium grained mean 1 76 volcanic sand 44 cm thick to pumice 5 cm thick that extends 320 m from the shoreline a subtle fining upward sequence was present in trench prb2 whereas prb1 prb3 and prb4 contained tc pam sediments that were laminated and showed little to no vertical gradation in grain size at prb we applied an inverse sediment transport model to reconstruct maximum flow depths using laboratory derived settling velocities and the distance from the berm the reconstructed flow depths at prb2 1 43 m prb3 1 36 m and prb4 1 34 m compare favorably with the observed estimate 1 51 m illustrating the applicability of the inverse sediment transport model to reconstruct flow depths of prehistoric landfalling tc s

late holocene tsunami traces on the western and southern coastlines of the peloponnesus greece abstract greece in particular the western and southern parts close to the subduction zone of the hellenic trench experiences strong earthquakes and subsequent tsunamis nevertheless field evidence of tsunamis from the late holocene is extremely rare our research along the coastlines of the western and southern peloponnesus resulted in new findings of tsunami impacts in the form of clusters and ridges of large boulders and thick tsunamigenic sand layers encountered in vibracores many boulders contained attached marine organisms which prove that they were transported from the foreshore environment against gravity by extreme wave events the attached organisms which have been dated by 14 c ams suggest that historical tsunami events of great energy occurred around 1300 cal ad a wood fragment found at the base of tsunami deposits in a vibracore from cape punta was dated to 250 cal ad

gravity driven deposits in an active margin ionian sea over the last 330 000 years in the ionian sea the subduction of the nubia plate underneath the eurasia plate leads to an important sediment remobilisation on the calabrian arc and the mediterranean ridge these events are often associated with earthquakes and tsunamis in this study we analyse gravity driven deposits in order to establish their recurrence time on the calabrian arc and the western mediterranean ridge four gravity cores collected on ridges and slope basins of accretionary prisms record turbidites megaturbidites slumping and micro faults over the last 330 000 years these turbidites were dated by correlation with a hemipelagic core with a multi proxy approach radiometric dating 18o b colour curve sapropels and tephrochronology the origin of the gravity driven deposits was studied with a sedimentary approach grain size lithology thin section geochemistry of volcanic glass the results suggest three periods of presence absence of gravity driven deposits a first on the western lobe of the calabrian arc between 330 000 and 250 000 years a second between 120 000 years and present day on the eastern lobe of the calabrian arc and over the last 60 000 years on the western lobe and a third on the mediterranean ridge over the last 37 000 years return times for gravity driven deposits are around 1000 years during the most important record periods the turbidite activity also highlights the presence of volcaniclastic turbidites that seems to be link to the etna changing morphology over the last 320 000 years

late quaternary pelagic sedimentation on the southern calabrian ridge and western mediterranean ridge eastern mediterranean abstract cores from plateaus lying some 150 200 m above the basin floors in areas of strong vertical relief visited during the cobblestone project consist entirely of pelagic marls with sapropels and tephras as minor lithologies all the plateau cores were correlated by means of isochronous lithologies and biostratigraphically calibrated a core from area 3 no 29 and two cores from area 4 no 45 and 6 were selected as reference sections and studied quantitatively in terms of grain sizes carbonate content and microfossil content faunal curves based on selected species of planktonic foraminifers correlate between the three cores which extend back in time to approximately 185 000 yr for area 4 and to 430 000 yr for area 3 winnowing resulted in a reduced sedimentation rate in area 3 in unusually high percentages of the coarser sediment fraction and in extended hiatuses at the top of the cores the highest temperature in surficial waters as indicated by the foraminiferal faunas is recorded in all three references sections at the base of an interval correlative with isotopic stage 5e 125 000 yr b p within sapropel s 5 clay mineralogy indicates basically uniform conditions in the two areas with the exception that smectite is more abundant in the calabrian ridge which is closer to its source area sicily sicily channel carbonates include calcite magnesian calcite and some dolomite sapropels sedimentary expression of stagnation represent up to 25 of the sedimentary column in an interval encompassing isotopic stage 5 through 7 the average organic carbon content in analysed sapropels is 3 1 versus 0 29 in normal pelagic sediments sapropels s 6 and s 8 are consistently accompanied by a foraminiferal fauna that is indicative of low salinity cool surficial waters whereas sapropels s 1 s 5 and s 7 occur in coincidence with the warmest peaks of the climatic faunal curve average sedimentation rate is 3 2 cm 1000 yr for core 29 5 5 cm 1000 yr for core 45 sedimentation rates calculated for basin cores are five to ten times higher sedimentation rates of sapropels and tephras are independent from regional sedimentation rates hiatuses in plateau cores correlate with debris flows in base of slope cores both occurring during times of enhanced bottom circulation and submarine erosion related to low stands of sea level in cold periods

complexity of holocene climate as reconstructed from a greenland ice core glaciochemical time series developed from summit greenland indicate that the chemical composition of the atmosphere was dynamic during the holocene epoch concentrations of sea salt and terrestrial dusts increased in summit snow during the periods 0 to 600 2400 to 3100 5000 to 6100 7800 to 8800 and more than 11 300 years ago the most recent increase and also the most abrupt coincides with the little ice age these changes imply that either the north polar vortex expanded or the meridional air flow intensified during these periods and that temperatures in the mid to high northern latitudes were potentially the coldest since the younger dryas event

discovery of minoan tsunami deposits the hellenic arc is a terrane of extensive quaternary volcanism one of the main centers of explosive eruptions is located on thera santorini and the eruption of the thera volcano in late minoan time 1600 1300 b c is considered to have been the most significant aegean explosive volcanism during the late holocene the last eruptive phase of thera resulted in an enormous submarine caldera which is believed to have produced tsunamis on a large scale evidence suggesting seawater inundation was found previously at some archaeological sites on the coast of crete however the cause of the tsunami and its effects on the area have not been well understood on the aegean sea coast of western turkey didim and fethye and crete gouves we have found traces of tsunami deposits related to the thera eruption the sedimentological consequences and the hydraulics of a thera caused tsunami indicate that the eruption of thera volcano was earlier than the previous estimates and the tsunami did not have disruptive influence on minoan civilization

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

evidence from the crow creek member pierre shale for an impact induced resuspension event in the late cretaceous western interior seaway the 1 3 m thick crow creek member is a unique marlstone with rip up clasts and a basal coarse layer in the upper cretaceous pierre shale in south dakota and nebraska although the member has been thought to represent a marine transgression along the eastern margin of the western interior seaway the presence of impact ejecta from the manson impact structure suggests an impact induced genesis an upper campanian in situ nannofossil assemblage with a lower campanian reworked assemblage from older niobrara chalk occurs in the crow creek at most localities the reworked assemblage decreases in abundance upward through the marlstone a pattern consistent with an origin involving gravitational settling rather than marine transgression gray marlstone clasts in the basal coarse layer have nannofossils derived from the underlying gregory member and niobrara chalk the reworked assemblage decreases in abundance with increased distances from the manson impact structure and the sioux ridge a paleotopographic high the nonuniform geographic distribution of reworking suggests that crow creek deposition was linked to the manson impact these observations and a fining upward trend the presence of impact ejecta and coeval deposition with the manson impact structure support a resuspension event origin for the crow creek member

climatic control of turbidite deposition on the madeira abyssal plain studies of sedimentation in the southwestern part of the madeira abyssal plain have revealed sequences of turbidites correlatable over thousands of square kilometres turbidites are sediments transported by turbidity currents and represent rapidly accumulated sedimentary units1 in this case in the distal part of the flow they are very fine grained and homogeneous occasionally with silty bases individual turbidites are separated by thin pelagic units which alternate from oozes to pelagic clays a stratigraphy for these pelagic units has been produced from combining coccolith distributions and lithological changes which enables comparison to cores containing only pelagic sediments from outside the turbidite province these comparisons show that turbidity currents cause no significant erosion in the area the major turbidites occur between lithological alternations which reflect global climate changes associated with glaciations and related eustatic sea level fluctuations turbidites have been linked with eustacy on previous occasions but only with low stands of sea level2 3 our work shows that turbidites are more likely to occur during regressions and transgressions rather than in the quiet periods between

recent marine lithofacies in cadiz bay sw spain sequences processes and control factors abstract the analysis of the lithofacies preserved in recent marine sediments in cadiz bay shows major fluctuations in the depositional regime which are characterized by significant energy variations drilling and geophysical data indicate the presence of coarse materials such as gravel imbricated shells and plant remains and frequent flow structures which have been interpreted as a result of the action of high energy events while the finest sediments present in the cores are interpreted as a consequence of the ordinary depositional regime fundamentally controlled by normal storm surge and tidal currents three types of sequence are differentiated very high energy vhe sequences high energy he sequences and low energy le sequences the vhe and he sequences were caused by highly energetic oceanic agents such as great waves generated by major storms or tsunamis there is no historical evidence of the action of sufficiently energetic storms while the geological setting of cadiz bay is located near the azores gibraltar fault the limit between the african and european plates points to tsunami action as being the most plausible option to explain the origin of these deposits the radiocarbon age indicates that these high energy events happened between 898 120 bc and 849 121 ad some of which coincide with several historically documented tsunamis affecting the cadiz coast this data indicates that the period from 849 ad to 1200 ad was a time of intense seismic and tsunamigenic activity

did the a d 365 crete earthquake tsunami trigger synchronous giant turbidity currents in the mediterranean sea in the ionian sea one of the most seismically active regions in the mediterranean subduction is commonly associated with uplift of coastal mountains enhanced erosion and seismic activity along the calabrian arc and hellenic arc thus potentially resulting in repetitive mass failures some of the turbidites observed in the deep basins are thick and prominent on seismic records because of the acoustic transparency of their upper structureless mud layer our high resolution study of the most recent of these megabeds the homogenite augias turbidite hat provides key proxies to identify pelagic sediments deposited following the catastrophic causative event radiometric dating in an area 150 000 km2 indicates that the different mediterranean so called homogenite deposits are in fact synchronous and were deposited during a single basin wide event within the time window a d 364 415 unlike interpretations that relate this turbidite to different triggering events including the santorini caldera collapse the turbidite can be traced back to a large tsunami sourced from the a d 365 crete megathrust earthquake correlation of the single event hat over a wide area of the mediterranean from the northern ionian sea to the mediterranean ridge and the anoxic tyro basin south of crete suggests that the a d 365 crete earthquake and tsunami must have produced devastating effects including widespread massive sediment remobilization in the eastern mediterranean sea

quantitative tsunami risk assessment in terms of building replacement cost based on tsunami modelling and gis methods the case of crete isl hellenic arc tsunami risk assessment is an important component of the planning for risk reduction we considered tsunami risk as a convolution of tsunami hazard vulnerability of the assets at risk e g buildings and the economic value exposed for testing the model a coastal segment at the west of heraklion capital city of crete isl greece was selected heraklion was hit in the past by strong tectonic and volcanic tsunamis generated along the hellenic arc in the mediterranean region the minoan tsunami produced by pyroclastic flows during the lba 17th century bc great eruption of thera santorini was selected as an extreme tsunami scenario for the hazard inundation zone determination through numerical simulation based on boussinesq equations for fully non linear waves it was found that the wave penetrates inland up to 1 2 km while the maximum water depth is 14 m the building stock was obtained from the 2011 national census data and validated with the use of orthophotomaps field inspection and google maps building vulnerability was determined with the use of the empirical gis tool damasche which is based on 2004 indian ocean tsunami building damage data and produces damage level by combining water depth and building construction types the damage level was translated to absolute monetary loss on the basis of cost flat rates determined officially for building replacement i e either reparation or reconstruction after the destructive earthquakes in greece during 2014 the method is applicable in other parts of the mediterranean and beyond provided that appropriate data are available

evaluation of tsunami impacts on shallow marine sediments an example from the tsunami caused by the 2003 tokachi oki earthquake northern japan abstract a combined approach of field geology and numerical simulation was conducted for evaluating the tsunami impacts on the shelf sediments the 2003 tokachi oki earthquake m 8 0 that occurred on 25 september 2003 off southeastern hokkaido northern japan generated a locally destructive tsunami maximum run up height of the tsunami waves reached 4 m above sea level in order to estimate the tsunami impacts on shallow marine sediments we compared pre and post tsunami marine sediments in water depths of 38 112 m in terms of grain size sedimentary structure and microfossil content decreases of fine fractions especially finer than very fine sand which led to coarsen the mean grain size were detected in the inner shelf of the northern part of the study area foraminiferal assemblages also changed in the coarsened sediments on the other hand the other shelf sediments largely unchanged or slightly fined we also simulated the tsunami wave velocity and direction and grain size entrained by the modeled tsunami the numerical simulation resulted in that the 2003 tsunami could transport very fine sand in water depths shallower than 45 95 m at the northern part of the study area this is comparable with the actual grain size changes after the tsunami had passed however some storms and tidal currents might also be possible to stir the surface sediments after the pre tsunami survey so we could not conclude that the grain size changes had been caused only by the tsunami nevertheless a combined approach of sampling and modeling was powerful for estimating the tsunami impacts under the sea

signatures of slope failures and river delta collapses in a perialpine lake lake lucerne switzerland historical reports from the 17th century document two destructive tsunamis with runups exceeding 5 m affecting proximal basins of lake lucerne switzerland one event in ad 1601 is coeval with a strong nearby earthquake mw ca 5 9 which caused extensive slope failures in many parts of the lake the second event in ad 1687 is associated with an apparently spontaneous partial collapse of the muota river delta this study combines high resolution bathymetry reflection seismic and lithological data in order to document the sedimentary and morphological signatures of the two subaqueous mass movements that probably generated the observed tsunamis such mass movements are significant as a common sedimentation process and as natural hazard in fjord type lakes and similar environments the deposits covering large parts of the basins with thicknesses reaching 10 m consist of two subunits a lower massflow deposit contains variably deformed sediments from the source areas its emplacement affected pre existing sediments incorporating thin sediment slices into the deposit and increasing its volume deep reaching deformation near this is an accepted article that has been peer reviewed and approved for publication in the sedimentology but has yet to undergo copy editing and proof correction

high resolution ice cores from us itase west antarctica development and validation of chronologies and determination of precision and accuracy shallow ice cores were obtained from widely distributed sites across the west antarctic ice sheet as part of the united states portion of the international trans antarctic scientific expedition us itase program the us itase cores have been dated by annual layer counting primarily through the identification of summer peaks in non sea salt sulfate nssso4 2 concentration absolute dating accuracy of better than 2 years and relative dating accuracy better than 1 year is demonstrated by the identification of multiple volcanic marker horizons in each of the cores tambora indonesia 1815 being the most prominent independent validation is provided by the tracing of isochronal layers from site to site using high frequency ice penetrating radar observations and by the timing of mid winter warming events in stable isotope ratios which demonstrate significantly better than 1 year accuracy in the last 20 years dating precision to 1 month is demonstrated by the occurrence of summer nitrate peaks and stable isotope ratios in phase with nssso4 2 and winter time sea salt peaks out of phase with phase variation of 1 month dating precision and accuracy are uniform with depth for at least the last 100 years

emplacement of the recent sedimentary cover and processes of deposition on the matapan trench margin hellenic arc abstract high resolution seismic surveys across the southern peloponnesus margin help to define the configuration and geometry of the unconsolidated sedimentary cover on the basis of acoustic character structural framework and results of dsdp cores two sedimentary units are distinguished a well stratified quaternary unit and an acoustically transparent pliocene series overlying a deep acoustic unit of different nature and age the plio quaternary series appears highly discontinuous along most of the margin the slope displays a series of basins where locally sediment thicknesses exceed 1000 m these basins separated by structural ridges generally devoid of sediment are often connected to the trenches by canyons the mechanism of sedimentation termed cascade feeding consists in a succession of depositions and of removals of sediment from basin to basin until the trench basins are reached the major physiographic features involved in this mechanism slope basins canyons ridges depressions trenches are directly controlled by structural trends oriented n140 and n70 related with the neotectonic evolution of the hellenic arc

the tsunamite problem the genetic term tsunamite is used for a potpourri of deposits formed from a wide range of processes overwash surges backwash flows oscillatory flows combined flows soft sediment deformation slides slumps debris flows and turbidity currents related to tsunamis in lacustrine coastal shallow marine and deep marine environments tsunamites exhibit enormous variability of features e g normally graded sand floating mudstone clasts hummocky cross stratification etc these sedimentary features may also be interpreted as deposits of turbidity currents turbidites debris flows debrites or storms tempestites however sedimentary features play a passive role when these same deposits are reinterpreted as tsunamites on the basis of historical evidence for tsunamis and their triggering mechanisms e g earthquakes volcanic explosions landslides and meteorite impacts this bipartite sedimentological vs historical approach which allows here classification of the same deposit as both turbidite and tsunamite has blurred the distinction between shallow marine and deep marine facies a solution to this problem is to classify deposits solely by a descriptive sedimentological approach the notion that tsunami waves can directly deposit sediment in the deep sea is unrealistic because tsunami waves represent transfer of energy and they are sediment starved during tsunamis and major storms submarine canyons serve as the physical link between shallow water and deep water environments for sediment transport tsunami related deposition involves four progressive steps 1 triggering stage offshore 2 tsunami stage incoming waves 3 transformation stage near the coast and 4 depositional stage outgoing sediment flows in this progression deep water deposition can commence only after the demise of incoming tsunami waves due to their transformation into outgoing sediment flows deposits of these sediment flows already have established names e g debrite and turbidite therefore the term tsunamite for these deposits is obsolete

size variations and long wave circulation within the january northern hemisphere circumpolar vortex 1946 89 abstract the close association between size variations in the northern hemisphere circumpolar vortex and surface and middle troposheric thermal characteristics makes vortex measurement a valuable tool in monitoring and understanding climate change unfortunately as with most hemispheric circulation indices measures of total vortex size offer little insight into regional changes in the vortex traditional approaches to vortex size calculation which are based upon planimeter measurements on a polar stereographic projection limit the ability to examine regional contributions to the total vortex and cannot be used to assess specific linkages between vortex expansion and contraction and the broader class of long wave circulation phenomena furthermore because the scale of the polar stereographic projection varies from one latitude to another interannual variations in planimeter vortex size measurements are influenced somewhat by the position of the vortex relative to the north pole many of these problem

a 200 year sulfate record from 16 antarctic ice cores and associations with southern ocean sea ice extent chemistry data from 16 50 115m deep sub annually dated ice cores are used to investigate spatial and temporal concentration variability of sea salt ss so4 2 and excess xs so4 2 over west antarctica and the south pole for the last 200 years low elevation ice core sites in western west antarctica contain higher concentrations of so4 2 as a result of cyclogenesis over the ross ice shelf and proximity to the ross sea polynya linear correlation analysis of 15 west antarctic ice core so4 2 time series demonstrates that at several sites concentrations of ssso4 2 are higher when sea ice extent sie is greater and the inverse for xsso4 concentrations of xsso4 2 from the south pole site east antarctica are associated with sie from the weddell region and west antarctic xsso4 2 concentrations are associated with sie from the bellingshausen amundsen ross region the only notable rise of the last 200 years in xsso4 around 1940 is not related to sie fluctuations and is most likely a result of increased xsso4 2 production in the mid low latitudes and or an increase in transport efficiency from the mid low latitudes to central west antarctica these high resolution records show that the source types and source areas of ssso4 2 and xsso4 2 delivered to eastern and western west antarctica and the south pole differ from site to site but can best be resolved using records from spatial ice core arrays such as the international trans antarctic scientific expedition itase

late pleistocene to holocene sedimentary fills of the cinarcik basin of the sea of marmara a giant rv marion dufresne piston core md01 2425 recovered from the 1276 m deep cinarcik basin of the sea of marmara documents characteristics of deep basin sedimentation influenced by large scale gravity controlled mass wasting processes and associated turbidite deposition during the late pleistocene to holocene a visual lithological description of the core reveals twenty major seismoturbidite layers 20 cm thick intercalated in hemipelagic type fine grained calcareous and slightly siliceous clays the thickness and frequency of the sesimoturbidite layers deposited during the lacustrine period prior to 12 3 cal ka bp is much greater than during the holocene marine period the sedimentary processes during deposition of seismoturbidites in the basin have been determined in this study using a combination of grain size parameters often the seismoturbidites show strong grain segregation with a sharp boundary between a coarse lower and a homogeneous upper part the traction carpet deposits formed at the base of a turbulent suspension and were produced in the lower coarse grained part whereas the homogeneous upper part was deposited by uniform suspensions following bedload deposition

10 be and delta 2 h in polar ice cores as a probe of the solar variability s influence on climate and discussion by using the technique of accelerator mass spectrometry it is now possible to measure detailed profiles of cosmogenic cosmic ray produced 10 be in polar ice cores recent work has demonstrated that these profiles contain information on solar activity via its influence on the intensity of galactic cosmic rays arriving in the earth s atmosphere it has been known for some time that as a result of temperature dependent fractionation effects the stable isotope profiles delta 2 o and delta 2 h in polar ice cores contain palaeoclimate information thus by comparing the 10 be and stable isotope profiles in the same ice core one can test the influence of solar variability on climate and this independent of possible uncertainties in the absolute chronology of the records we present here the results of such a comparison for two antarctic ice cores one from the south pole covering the past ca 1000 years and one from dome c covering the past ca 3000 years

sea level pressure variability in the amundsen sea region inferred from a west antarctic glaciochemical record using european center for medium range weather forecasts ecmwf numerical operational analyses sea ice extent records and station pressure data we investigate the influence of sea level pressure variability in the amundsen sea region on a west antarctic siple dome glaciochemical record empirical orthogonal function analysis of the high resolution siple dome multivariate ice core chemical time series record sdeof1 documents lower tropospheric transport of sea salt aerosols to the site during 1985 1994 the sdeof1 record of high low aerosol transport corresponds to anomalously low high sea level pressure slp in the amundsen sea region spatial correlation patterns between ecmwf monthly slp fields and the annual sdeof1 record suggest that a majority of sea salt aerosol is transported to siple dome during spring september october and november analysis of zonal and meridional wind fields supports the slp sdeof1 correlation and suggests the sdeof1 record is sensitive to changes in regional circulation strength no relationship is found between sea ice extent and the sdeof1 record for the period 1973 1994 to investigate the sdeof1 record prior to ecmwf coverage a spring transpolar index stpi is created using normalized slp records from the new zealand and south america antarctic peninsula sectors and is significantly correlated at least 95 c l with the sdeof1 record on an annual r 5 0 32 p 0 001 and interannual 3 years r 5 0 51 p 0 001 basis dominant periodicities 3 3 and 7 1 years in the annual sdeof1 record 1890 1994 a d suggest that a portion of the recorded interannual variability may be related tropical extratropical enso teleconnections changes in the periodic structure of the full 850 1994 a d siple dome record suggests a shift in slp forcing during the little ice age 1400 1900 a d interval

late quaternary sedimentation in the tyro and kretheus basins southeast of crete abstract this paper summarizes micropaleontologic foraminifera calcareous nannoplankton radiolaria pteropods and pollen grains and sedimentologic piston core data from the eastern mediterranean tyro and kretheus basins 14 c datings indicate a holocene age for the tyro basin cores the latter show anoxic bottom conditions throughout while the kretheus basin core indicates anoxic conditions prior to 3000 years ago and oxic conditions after that time resedimentation through slumps turbidity currents and from suspension resulted in high sediment accumulation rates in both basins reworking in the tyro basin predominantly originated from the basin flanks while the presence of common to abundant metamorphic clastics in the kretheus basin points to a more distant source the minoan eruption of santorini ca 3350 yrs b p which is supposed to have caused a gigantic tsunami is linked to the presence of turbidites and a thick homogenite in the tyro basin the same event may be responsible for the initiation of oxic conditions in the kretheus basin