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

large bedform generated by the 2011 tohoku oki tsunami at kesennuma bay japan abstract the 11 march 2011 m w 9 0 tohoku megathrust earthquake off the pacific coast of japan was a salient event in the history of japan the resultant huge tsunami the 2011 tohoku oki tsunami inundated a vast coastal area of northeastern japan causing widespread devastation twenty days after the tsunami we analyzed the impact of the tsunami on the sea bottom of the kesennuma inner bay using side scan sonar to explore the damage and bathymetric change in the harbor herein we present the first direct evidence that the sea bottom sediments of around 10 15 m were largely reworked by the tsunami to thickness of a few meters and that large dunes were formed by the tsunami considering that the sea wave influence is as weak as it is inside the inner bay the potential exists that even meter thick paleo tsunami deposits are preserved in shallow sea bottoms with large bedforms this finding will be a stepping stone to future geological studies of tsunami effects in shallow sea regions

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

soft sediment deformation structures induced by cyclic stress of storm waves in tempestites miocene guadalquivir basin spain the identification of triggering agents for soft sedimentation structures is an enigmatic geological problem mainly seismic induced soft sediment structures have been recognized in ancient sediments rather than those resulting from storm waves we analyse soft sediment deformation structures in upper miocene calcarenitic tempestites of the guadalquivir basin southern spain the most common structures are load casts which vary in height and width from 10 centimetres to several metres the structures are always restricted to a small part of the stratigraphic sections in exclusive association with tempestites the analysed soft deformation structures are interpreted to be the result of liquidization processes chiefly from their inferred depositional environment and subordinately from the deformation style we have devised basic criteria to identify the trigger mechanism in these soft sediment deformation structures the liquefaction was triggered by pore pressure changes induced by cyclic and residual stress of storm waves

earthquake triggered soft sediment deformation structures seismites in travertine deposits abstract earthquakes related soft sediment deformations seismites are relevant structures to help reconstructing the palaeoseismicity in a region nevertheless although seismites have been described for a large variety of palaeo environments and stratigraphic settings they are rare and in some cases ambiguous structures in this paper we document for the first time impressive seismites affecting a latest quaternary travertine deposit located in southern tuscany serre di rapolano italy these structures are extremely relevant as seismites have been never described for this kind of terrestrial deposits the seismites developed within a 2 5 m thick stratigraphic succession made of alternating terrigenous and carbonate sediments embedded within the travertine deposits earthquake produced liquefaction and fluidization of some terrigenous levels and the injection of fluidized silty sediments dykes and sills into carbonate and terrigenous levels slumped levels and associated decollement surfaces produced highly non cylindrical folds overall induced by the loss of brittle shear strength along the basin slopes the occurrence of these soft sediment deformations implies an important seismic event that took place in a time spam encompassed between 84 8 and 48 92 5 08 ka in an area characterized by low seismicity and scarce knowledge of its seismotectonic setting their spectacular exposition and preservation in saw cuts of an abandoned quarry cava oliviera quarry highlights their relevance and importance

reply to comment by luigi vigliotti on lost tsunami about 8 3 ka ago a devastating tsunami flooded thecoasts of the eastern mediterranean sea pareschi et al 2006c that tsunami was triggered by a landslide from thecollapse of the eastern flanks of mt etna volcano sicily italy in turn inducing 1 a scar on volcano slopes namedvalle del bove 2 inland deposits chiancone and milounits dated 7 6 8 3 ka cal b p calvari and groppelli 1996 calvari et al 1998 and 3 offshorelandslidedeposits pareschi et al 2006a the tsunami had a largeimpact effecting southern italy western greece and northafrica including tunisia to libya egypt southern turkey syria lebanon and israel in israel the tsunami ravaged theneolithic village of atlit yam caused the death of villagersand animals filling a water well and destroying village huts pareschi et al 2006c 2007 an early holocene sea levelrise dated 8 350 8 250 calendar year b p matches thetiming of the mt etna tsunami the consequent flooding ofcoastal areas led to the sudden loss of land favoured byearly farmers and initiated an abrupt expansion of activityacross europe turney and brown 2007

small scale hummocky cross stratification in turbidites a form of antidune stratification small scale hummocky cross stratification occurs in upper cretaceous calciclastic turbidites exposed in the western basque pyrenees facies associations and microfossil assemblages indicate slope to base of slope bathyal depositional environments it is developed in the fine grained portion of beds and displays spacings mostly between 0 2 and 0 7 m the beds fine upward with no sharp grain size breaks or mud partings suggesting that deposition occurred during a single flow event hummocky intervals are 0 1 0 8 m thick and consistently grade laterally and vertically into flat planar laminations of bouma b divisions suggesting that deposition occurred under upper flow regime conditions they have wave like geometries with laminae continuous across crests and troughs and display a ratio of wavelength to estimated underflow thickness of 11 3 12 8 combining the above observations and inferences these examples of small scale hummocky cross stratification are interpreted as a form of antidune stratification generated by standing waves along the interface of a thinner denser underflow main body tail of the turbidity current and an overlying thicker low density layer this occurrence is further evidence that small scale hummocky cross stratification is multigenetic and therefore not indicative of a particular flow condition or depositional environment

an ams radiocarbon method to determine the emplacement time of recent deep sea turbidites abstract this paper reports the evaluation of a novel method based on accelerator mass spectrometer ams radiocarbon dating of planktonic foraminifera to evaluate the times of emplacement of recent deep sea turbidites it assumes that the standing stock of relatively large 150 m planktonic foraminifera in the bioturbated surface mixed layer of box cores represents an integration of the flux from the water column since the turbidite was emplaced and exploits the potential of the ams method to analyse the resultant small samples which can be readily separated the method is evaluated by application to three atlantic turbidites which form the present day sediment surfaces on the horseshoe madeira and tagus abyssal plains the time of emplacement of madeira abyssal plain turbidite is estimated at 1120 730 and 870 years before present each 120 140 years in three different cores the resultant weighted mean emplacement time 930 76 years before present is somewhat older than previous estimates by geochemical methods the times of emplacement for the horseshoe 240 and 140 years before present each 120 years and tagus 300 120 years before present abyssal plains are both consistent with initiation by the lisbon earthquake of 1755

extensive soft sediment deformation structures in the early darriwilian middle ordovician shallow marine siliciclastic sediments formed on the baltoscandian carbonate ramp northwestern estonia abstract the nearshore middle ordovician early darriwilian deposits of the baltoscandian basin formed on the flank of tectonically stable fennoscandian shield comprise numerous soft sediment deformation structures the areal extent of the deformed interval extends up to 9000 km 2 from nw estonia to se sweden the deformation structures occur within a meter scale sandstone horizon that includes load casts flame structures ball and pillow morphologies up to 2 m wide sedimentary dykes autoclastic breccias sand volcanoes and other related soft sediment deformation structures evidently these deformation structures formed during a single seismic event that caused liquefaction and fluidization of the water saturated unconsolidated shallow marine sediments within almost the entire sandstone unit pakri formation probably a unique catastrophic earthquake of magnitude 7 or higher occurred in this region penecontemporaneously with the deposition of these sediments the ultimate cause of seismic event of such magnitude in the tectonically stable baltoscandian basin is unclear however deposition and deformation of the pakri formation fall within the middle ordovician meteoritic bombardment period which resulted from the disruption of a large parent body in the asteroid belt approximately 470 ma ago this in turn suggests a potential impact origin for the single catastrophic earthquake in the tectonically stable study region although impact crater of suitable age is currently not known from the region then previous studies have documented some impact metamorphic shock lamellae i e pdfs and abundant extraterrestrial chromite grains from the deformed sediments

a re analysis of the late bronze age eruption and tsunami of santorini greece and the implications for the volcano tsunami hazard the paroxysmal eruption of santorini ca 3500 bp referred to as the late bronze age lba eruption probably generated multiple tsunami their occurrence and impacts being cited frequently in scientific papers and articles this paper examines what is known about any lba tsunami noting possible mechanisms of generation and identifying sedimentological traces firstly the eruption sequence is outlined providing the context in which tsunami genesis may have occurred secondly the arguments forwarded for the tsunami and a summary of the evidence is given thirdly results of a new geological investigation for lba tsunami deposits at 41 coastal sites from crete and kos are presented the data are used to test the hypothesis that the lba eruption generated an east mediterranean wide tsunami it will be seen that no terrestrial geological evidence is identified the paper re examines the original arguments presented for lba tsunami challenging them because their founding assumptions are flawed together the new data and the re analysis of the original tsunami hypothesis indicate that there is insufficient evidence to demonstrate that any significant far field tsunami propagated throughout the entire east mediterranean as frequently purported some terrestrial evidence exists to suggest localised near field tsunami inundation there is good submarine evidence however to suggest that a tsunami was focused to the w and wsw the results have important implications for understanding the volcano related tsunami hazard within the region and elsewhere

prehistoric earthquake history revealed by lacustrine slump deposits five strong paleoseismic events were recorded in the past 15 k y in a series of slump deposits in the subsurface of lake lucerne central switzerland revealing for the first time the paleoseismic history of one of the most seismically active areas in central europe although many slump deposits in marine and lacustrine environments were previously attributed to historic earthquakes the lack of detailed three dimensional stratigraphic correlation in combination with accurate dating hampered the use of multiple slump deposits as paleoseismic indicators this study investigated the fingerprint of the well described a d 1601 earthquake i vii viii mw 6 2 in the sediments of lake lucerne the earthquake triggered numerous synchronous slumps and megaturbidites within different subbasins of the lake producing a characteristic pattern that can be used to assign a seismic triggering mechanism to prehistoric slump events for each seismic event horizon the slump synchronicity was established by seismic stratigraphic correlation between individual slump deposits through a quasi three dimensional high resolution seismic survey grid four prehistoric events dated by accelerator mass spectrometry 14c measurements and tephrochronology on a series of long gravity cores occurred at 2420 9770 13 910 and 14 560 calendar yr ago these recurrence times are essential factors for assessing seismic hazard in the area the seismic hazard for lakeshore communities is additionally amplified by slump induced tsunami and seiche waves numerical modeling of such tsunami waves revealed wave heights to 3 m indicating tsunami risk in lacustrine environments

tsunami induced conglomerates in miocene upper bathyal deposits chita peninsula central japan abstract the tsubutegaura conglomeratic tsunamiites occur in the middle section of the miocene storm related sand silt alternation system in the chita peninsula central japan deposition of the system in the upper bathyal environment in a bay and synsedimentary seismic activity has been elucidated by palaeontological palaeogeographical and sedimentological studies two coupled units each built up by a conglomerate layer with an overlying sandstone layer and the alignment of lenticular sedimentary bodies are exceptional in this sequence some typical lenticular bodies confined within sedimentary troughs consist of a boulder bearing conglomerate layer and calcareous sandstone layer of the lower couple and another conglomerate layer of the upper couple the tuffaceous sandstone layer of the upper couple is distributed more widely than the other lithologies the framework gravels in the coupled conglomerates form a clast supported fabric and are quite notably monomictic the clasts are angular and imbricated partly forming peculiar gravel clusters due to traction current transportation conspicuous laminations develop in the coupled sandstone layers antidunes with chute and pool structure in the upper couple sandstone layer indicate deposition from an upper flow regime current on the other hand the calcareous composition of the lower couple sandstone layer reveals shallow water provenance thixotropic deformations and diastasis cracks in the siltstone bed immediately beneath the layers of the couples show that a severe earthquake tremor and a rapid change of water pressure occurred just before the deposition of the tsunamiites submarine debris flows due to collapse of a fault scarp in a shallow bank and the ensuing wash by two pulses of the tsunami induced ebb current comprise the scenario for the formation of the tsubutegaura conglomeratic tsunamiites

sedimentology and possible paleoceanographic significance of mudstone turbidites and associated deposits of the pen argyl member martinsburg formation upper ordovician eastern pennsylvania abstract the pen argyl member the stratigraphically highest unit of the upper ordovician martinsburg formation of eastern pennsylvania consists of the three mudstone facies laminated mudstone uniform mudstone and black shale these deposits conformably overlie a coarsening upward sequence of fine grained and classic sandstone turbidites of the underlying bushkill and ramseyburg members respectively petrographic and x radiographic analysis suggests that laminated and uniform mudstone facies beds accumulated from muddy turbidity currents interbedded black shale facies beds however are interpreted to reflect slow gravitational settling of sediment in a density stratified anoxic basin the marked transition from sandstone and siltstone turbidite deposits of the ramseyburg member to mudstone turbidite and black shale deposits of the pen argyl member may reflect the combined effects of a caradocian rise in sea level increased organic carbon production lack of sand size sediment and a tropical to subtropical location of the basin density stratification such a model however does not explain adequately the very thick laminated and uniform mudstone facies beds common only to the pen argyl member an alternative hypothesis involves amplification of global eustatic and climatic related oceanographic effects by local or basinal influences the very thick beds of the laminated and uniform mudstone facies by comparison with lithologically similar deposits of the eastern mediterranean are interpreted to have been ponded in a topographically restricted basin accordingly deposition of the pen argyl member may record a significant change in basin morphology from a wide extensive basin to a topographically restricted or enclosed anoxic basin

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

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

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

the tsunami phenomenon abstract with human activity increasingly concentrating on coasts tsunamis from japanese tsu harbour nami wave are a major natural hazard to today s society stimulated by disastrous tsunami impacts in recent years for instance in south east asia 2004 or in japan 2011 tsunami science has significantly flourished which has brought great advances in hazard assessment and mitigation plans based on tsunami research of the last decades this paper provides a thorough treatise on the tsunami phenomenon from a geoscientific point of view starting with the wave features tsunamis are introduced as long shallow water waves or wave trains crossing entire oceans without major energy loss at the coast tsunamis typically show wave shoaling funnelling and resonance effects as well as a significant run up and backflow tsunami waves are caused by a sudden displacement of the water column due to a number of various trigger mechanisms such are earthquakes as the main trigger submarine and subaerial mass wastings volcanic activity atmospheric disturbances meteotsunamis and cosmic impacts as is demonstrated by giving corresponding examples from the past tsunamis are known to have a significant sedimentary and geomorphological off and onshore response so called tsunamites form allochthonous high energy deposits that are left at the coast during tsunami landfall tsunami deposits show typical sedimentary features as basal erosional unconformities fining upward and landward a high content of marine fossils rip up clasts from underlying units and mud caps all reflecting the hydrodynamic processes during inundation the on and offshore behaviour of tsunamis and related sedimentary processes can be simulated using hydro and morphodynamic numerical models the paper provides an overview of the basic tsunami modelling techniques including discretisation guidelines for appropriate temporal and spatial resolution as well as the nesting method furthermore the boussinesq approximation a simplification of the three dimensional navier stokes equations is presented as a basic theory behind numerical tsunami models which adequately reflects the non linear dispersive wave behaviour of tsunamis the fully non linear boussinesq equations allow the simulation of tsunamis e g in the form of n waves based on the various subtopics presented recommendations for future multidisciplinary tsunami research are made it is especially discussed how the combination of sedimentary and geomorphological tsunami field traces and numerical modelling techniques can contribute to derive locally relevant tsunami sources and to improve the assessment of tsunami hazards considering the individual pre history and physiogeographical setting of a specific region

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

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

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

ocean interactions with the base of amery ice shelf antarctica using a two dimensional ocean thermohaline circulation model we varied the cavity shape beneath amery ice shelf in an attempt to reproduce the 150 m thick marine ice layer observed at the gi ice core site most simulations caused melting rates which decrease the ice thickness by as much as 400 m between grounding line and g1 but produce only minor accumulation at the ice core site and closer to the ice front changes in the seafloor and ice topographies revealed a high sensitivity of the basal mass balance to water column thickness near the grounding line to submarine sills and to discontinuities in ice thickness model results showed temperature salinity gradients similar to observations from beneath other ice shelves where ice is melting into seawater modeled outflow characteristics at the ice front are in general agreement with oceanographic data from prydz bay a freshwater flux across the grounding line derived from melting beneath the grounded ice sheet would have to be anomalously large to produce the basal marine ice layer and account for the ice shelf water outflow we concur with morgan s inference that the g 1 core may have been taken in a basal crevasse filled with marine ice this ice is formed from water cooled by ocean ice shelf interactions along the interior ice shelf base

mapping the dayside ionosphere to the magnetosphere according to particle precipitation characteristics a long standing and vexing problem in magnetospheric physics is mapping the ionosphere to the magnetosphere to date almost all information on the topic has come from magnetic field mappings herein a complementary approach is tried regions are identified based on the plasma characteristics as observed by low altitude satellites using an automated identification scheme applied to approximately 60 000 individual satellite passes through the dayside oval probability maps are computed for observing various types of plasma precipitating into the ionosphere the synthesis of the various individual maps allows the construction of an ionospheric map into the magnetosphere based on plasma characteristics the results suggest a cusp which is about 2 5 hours in total local time extent an llbl which typically extends to about 0900 mlt and a mantle which reaches to about 0800 1600 consistent with earlier results the extension of the nightside region of discrete aurora into the dayside is far more substantial at dusk than at dawn

late quaternary lacustrine paleo seismic archives in north western alps examples of earthquake origin assessment of sedimentary disturbances abstract the late quaternary sedimentary fills of several lakes of the north western alps are revealed to be possible paleo seismological archives in a moderately active seismo tectonic region the strongest historically reported events can be correlated with specific layers whose textures result from different processes i mass failures of sub aqueous slope deposits especially delta foresets evolving into hyperpycnal currents influenced by seiche effects and or multiple reflections on lake basin slopes ii in situ liquefaction and flowage and iii micro fracturing based on identification of the sedimentary signature of a well documented historical earthquake the paleoseismic interpretation can be extrapolated back to 16 000 yrs bp with a reconstruction of a time series and textural identification of slope failure related turbidites the most frequent earthquake signature the obtained time series are compatible with historical seismicity in terms of recurrence interval

setting and tectonic evolution of some eastern mediterranean deep sea basins abstract nine discrete deep sea basins seven from the calabrian and mediterranean ridges and two from the strabo trench were explored geologically during several cruises carried out from 1978 to 1984 in the eastern mediterranean the seven basins displaying similar geological features calabrian and mediterranean ridges may be divided into three groups on the basis of their size 1 very small basins botticelli and raffaello basins whose area ranges from 1 1 to 4 3 km 2 2 small basins ares aphrodite and katia basins from 7 to 13 km 2 and 3 large basins bannock and cleft basins from 22 to 74 km 2 the two basins from the strabo trench tyro and kretheus basins whose areas range from 16 to 20 km 2 are considered separately tectonics is the most important element affecting basin formation processes progressive folding and faulting of messinian pliocene and quaternary sediments in the calabrian and mediterranean ridges allows the infiltration of water into the subbottom and dissolution of messinian evaporites so that collapse of the overlying unconsolidated plio quaternary cover creates local distensive tectonics superimposed on the regional compressive tectonic setting the size of the basins reflects different steps in this process very small basins are related to the fracturing occurring at the top of anticlines small basins originate when anticlines are faulted and large amounts of water are able to reach the evaporites and increase the intensity of leaching finally large basins are related to regional tectonic lineaments both compressive large reverse faults overthrusts and strike slip salt diapirism may be associated with some of these situations the process responsible for the tyro and kretheus basins formation is the pull apart mechanism connected with the strike slip motion occurring in that area the geometric position of subaqueously dissolved evaporites seems to influence the environment on the basin floor brines originating from the dissolution of buried evaporites are thought to disperse in the subbottom whereas brines originating from dissolution of evaporites cropping out on the basin walls can flow to the floor and cause stagnation only if the shape of the basin prevents the action of bottom currents

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

earthquakes as a triggering mechanism for debris flows and turbidites on the calabrian ridge abstract debris flows and turbidites have been described in piston cores bottom photographs and side looking sonar records from basin floors amid the rugged irregular topography of the calabrian ridge a sediment transport process is inferred which began with a rotational slump on the steep basin wall subsequently transformed into a debris flow and turbid cloud such events occurred approximately every 1500 years because the debris flow turbidite deposits are correlative between basins some relatively widespread mechanism such as an earthquake is required to initiate the slope failure the estimated intensity of ground shaking as a result of historical earthquakes on the nearby calabrian and hellenic arcs has been used to develop a relationship between frequency of occurrence and intensity of ground shaking extrapolation of this relation to infrequent large magnitude events shows that the 1500 yr event is small enough to be geologically plausible but large enough to cause slope failure on basin walls it is possible that the historical record fortuitously contains one of these large magnitude long repeat time events which may have caused the most recent of the observed debris flows in 1903

stratigraphy and sedimentation in the anoxic bannock basin eastern mediterranean abstract ten gravity and or piston cores raised from the floor and the eastern flank of the bannock basin and from nearby plateaus were investigated lithologically and biostratigraphically the bannock basin is a large rimmed depression with a vertical relief of over 600 m containing deep seated brines the brines are derived from submarine dissolution of messinian evaporites in a physiographic setting deep rimmed basin that does not permit dilution and removal by bottom currents plateau cores range in age from holocene emiliania huxleyi acme zone to middle pleistocene pseudoemiliania lacunosa zone they consist of low sedimentation rate pelagic sediments with sapropels and tephras as minor isochronous lithologies two cores on the flanks recovered pliocene pelagic sediments one of these cores displays an unconformable contact between holocene anoxic sediments and early pliocene reticulofenestra pseudoumbilica zone marls the other core is entirely pliocene consisting of a debris flow with a matrix that is referred to the discoaster tamalis subzone cores from the deeper part of the basin consist of laminated non bioturbated poorly oxygenated dark sediments rich in h 2 s and containing large gypsum crystals organic carbon content is higher than in normal eastern mediterranean pelagic sediments but lower than in true sapropels the kerogen is dominated by amorphous organic matter although the oxygen content of the bottom waters was not measured sedimentary evidence suggests that poorly oxygenated but not entirely anoxic conditions exist in the basin at the sediment water interface in particular benthic foraminifers would be much less abundant than they actually are and org c content would be higher if bottom waters were anoxic poor oxygenation started to develop in the bannock basin some 180 ka b p after the deposition of sapropel s 6 as documented in core 84 02 this long lasting period of anoxia strongly differs from the short anoxic episodes in the eastern mediterranean that were controlled by glacial interglacial changes the bannock basin anoxia is a result of brine formation causing strong density stratification with a density contrast 20 that is much higher than the density contrast derived from changes in thermohaline circulation during glacial interglacial times during these eastern mediterranean basin wide euxinic episodes the boundary between oxygenated and anoxic waters was much shallower than the 3200 m interface recorded in the bannock basin reworked and displaced foraminiferal faunas were found in the pliocene sediments recovered in the flank cores in particular the occurrence of abraded tests of the shallow water form elphidium spp of bulimina costata and of other displaced taxa does suggest that the area was subject to deposition by turbidity currents originating on the african margin and that in pliocene times no rimmed basin was in existence

impact of the minoan tsunami of santorini simulated scenarios in the eastern mediterranean 1 we have simulated the impact of the tsunami generated by the late bronze age lba volcanic eruption of santorini on the eastern mediterranean two different tsunami triggering mechanisms were considered a caldera collapse and pyroclastic flows surges entering the sea simulations include the worst input conditions in order to evaluate the maximum possible impacts but also lighter input conditions compatible with the lack of any tsunami trace on the northern coasts of crete in all the simulations tsunami propagation is mainly confined to the southern aegean outside the aegean the tsunami impact was negligible and not responsible for the slide slumping of fine grained pelagic and or hemipelagic sediments considered the sources of the sporadically located sea deposits in the ionian sea and of the widespread megaturbidite deposits localized in the ionian and sirte abyssal plains

truncated flame structures within a deposit of the indian ocean tsunami evidence of syn sedimentary deformation this study reveals the three dimensional morphology and syn sedimentary formation processes of a deformation structure termed truncated flame structures which is found in a terrestrial tsunami deposit in southern thailand that formed during the 2004 indian ocean tsunami the structure was found at the boundary between a lower fine grained layer and an upper coarse grained layer that are related to two runup events in order to confirm the morphology of the structure the authors excavated two trenches and an opencast pit when viewed in a cross section oriented parallel to the direction of the runup current the deformed boundary has an irregularly bulging profile similar to that observed in flame structures the protruding structures are inclined towards the downstream direction of the runup current and are truncated horizontally along their upper surface by parallel laminations in the overlying layer when viewed in a cross section oriented perpendicular to the current direction it appears that parts of the upper layer descend into the lower layer as lobate masses in places these masses are completely detached from the main part of the upper layer forming circular or elliptical shapes the contact between the lower layer and the main part of the upper layer is a planar truncation surface opencast excavation of the contact surface revealed that the deformed structures have flat sinuous horseshoe crests that open in a downstream direction it is possible for the runup current to generate shear stress such that it deforms the boundary into a truncated flame structure moreover the observations made in this study indicate the syn sedimentary development of the structure deformation and truncation occurred simultaneously in association with the runup current that formed the upper layer truncated flame structures can be used as a criterion in identifying the syn sedimentary deformation of substrate the structures are indicative of unidirectional flow with sufficiently high shear velocity to deform unconsolidated substrate as in the present case the truncated flame structures may be characteristic of tsunami events that involve strong unidirectional currents on land due to the extraordinarily long wave period of tsunamis rather than other events such as storm surges or flooding

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

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

holocene sedimentation in the tectonically active tekirdag basin western marmara sea turkey abstract the effects of various depositional conditions and active tectonics on the late holocene sedimentation in the tekirdag basin west of the marmara sea were investigated in 11 gravity cores and on 3 seismic profiles representing shelf to slope to deep basin floor environments except for the two coarser grained avg 60 sand and gravel and calcareous avg 25 caco 3 shelf cores sediments in the slope and basin floor cores constitute low calcareous avg 12 caco 3 and terrigenous mud 90 silt and clay the occurrences of relatively higher total organic carbon contents in sediments from the southern slope 1 14 1 38 compared to that from the northern slope 0 37 1 2 indicate significant input from the southern rivers the presence of silty sandy laminations within the mud matrix of the cores and chaotic and mounded reflection configurations on the seismic profiles from the slope and basin floor environments all suggest the effects of gravity mass movements of sediments slides slumps turbidites most likely due to seismotectonic events earthquakes however it was difficult to establish a basin wide correlation between the historical earthquake events in the region and the positions of silty sandy laminations in dated deep sea sediment cores due to complicated other events such as repeated river run off and floods increased sediment load and slope failure the water contents of sediments from the basin floor avg 10 30 are significantly lower than those from the slope sediments avg 32 46 the former can be explained by the influences of synsedimentation with tectonics and compaction between the north and south boundary sub faults of the naf system whereas the latter shows fluidization of slope sediments during sliding and slumping radiocarbon dated base sections from three cores revealed that sediment deposition at these sites commenced about 4700 bp when the late holocene depositional conditions changed from the formation of upper sapropels to the present state the increases of organic carbon contents at or near the base sections of the cores support this contention

modelling of tsunami generated by the giant late bronze age eruption of thera south aegean sea greece summary tsunami generated by the late bronze age lba eruption of thera were simulated using synthetic tide records produced for selected nearshore 20 m depths sites of northern crete the cyclades islands sw turkey and sicily inundation distances inland were also calculated along northern crete modelling was performed by incorporating fully non linear boussinesq wave theory with two tsunamigenic mechanisms the first involved the entry of pyroclastic flows into the sea assuming a thick 55 m 30 km3 flow entering the sea along the south coast of thera in three different directions all directed towards northern crete then a thin pyroclastic flow 1 m 1 2 km3 entering the sea along the north coast of thera directed towards the cyclades islands flows were modelled as a solid block that slowly decelerates along a horizontal surface the second mechanism assumed caldera collapse of 19 km3 and 34 km3 modelled as a dynamic landslide producing rapid vertical displacements calculated nearshore wave amplitudes varied from a few metres to 28 m along northern crete from pyroclastic flows and up to 19 m from caldera collapse 34 km3 volume inundation distances on crete were 250 450 m waves produced by pyroclastic flows were highly focused however as a function of sea entry direction smaller volume pyroclastic flows produced nearshore wave amplitudes up to 4 m in the cyclades islands north of thera wave amplitudes in the cyclades from smaller volume caldera collapse 19 km3 were up to 24 m whereas in sw turkey were as low as 2 1 and 0 8 m didim and fethye where lba tsunami deposits have been found wave amplitudes for the larger volume caldera collapse 34 km3 were generally 2 5 3 times larger than those generated by the smaller volume collapse 19 km3 these results provide estimates for understanding possible consequences of tsunami impact in lba coastal zones thus providing criteria at archaeological sites for detecting inundation damage as well as for contemporary hazard assessment they also provide additional criteria for deciphering homogenite layers in the abyssal stratigraphy of the ionian and eastern mediterranean seas

turbidite paleoseismology in the calabrian arc subduction complex ionian sea 1 the calabrian arc subduction system is part of the africa eurasia plate boundary is one of the most seismically active regions in the mediterranean sea and has been struck repeatedly by destructive historical earthquakes in this study we investigate the effects of historical earthquakes on abyssal marine sedimentation through the analysis of the turbidite record we collected gravity cores in tectonically controlled basins where the eastern mediterranean pelagic sequence is interbedded with resedimented units textural micropaleontological geochemical and mineralogical signatures reveal three turbidite events in the last millennium we dated the turbidite sequences from two different cores using different radiometric methods whereas the average time interval between successive turbidite beds was estimated from pelagic sediment thickness and sedimentation rates chronologies were refined through age modeling that provided age ranges 2 of each turbidite bed the results suggest that turbidite emplacement was triggered by three historical earthquakes recorded in the area i e the 1908 1693 and 1169 events their magnitude epicentral location and associated tsunamis support causative faults located in the ionian sea the source for all the turbidites as inferred from their mineralogy is the metamorphic basement outcropping in southern calabria and or northeastern sicily turbidite composition and cable breaks for the 1908 event have been used to infer likely traveling paths and seismogenic faults in the subduction system our findings suggest that ionian sea turbidites represent more than 80 of sedimentation and may be seabed archives of paleo earthquakes capable of reconstructing seismicity back in time during several earthquake cycles

a seismite in triassic gypsum deposits grabfeld formation ladinian southwestern germany an approximately 1 m thick gypsum bed and its underlying 45 cm dolomite bed with variable soft sediment deformation structures are described from the grundgips member of the grabfeld formation middle keuper ladinian in southwestern germany the deformation structures are mainly convolutions folds cusps domes and off shooting dykes and less common brecciation or faulting these deformation structures are interpreted to be caused by liquefaction and or fluidization of the semiconsolidated sediments by a seismic shock of approximately magnitude 6 7 palaeoseismicity is thought to be related with a nearby wrench fault system associated with a major suture zone of the variscan basement

a depositional model for seismo turbidites in confined basins based on ionian sea deposits abstract this study investigates ionian sea seismo turbidite st deposits that we interpret to be triggered by major historic earthquakes and tsunamis in the calabrian arc st beds can be correlated with the ad 1908 mw 7 24 messina ad 1693 mw 7 41 catania and ad 1169 mw 6 6 eastern sicily earthquakes while two previously unknown turbidites might have been generated by the ad 1818 mw 6 23 catania and ad 1542 mw 6 77 siracusa earthquakes textural micropaleontological geochemical and mineralogical signatures of sts reveal cyclic patterns of sta stb stc and std sedimentary units for each earthquake with an associated tsunami the sta unit contains multiple st stacks with different mineralogy geochemistry foraminiferal assemblages and sedimentary structures that are deposited from synchronous multiple slope failures and turbidity currents the stb homogenite graded mud unit overlying the sta unit is deposited by the waning flows of the multiple turbidity currents that are trapped in the ionian sea confined basin the stc laminated and marine sourced unit results from seiching of the confined water mass that appears to be generated by earthquake ruptures combined with tsunami waves the std unit is a tsunamite cap deposited by the slow settling suspension cloud created by tsunami wave backwash erosion of the shoreline and continental shelf this tsunami process interpretation is based on the textural gradation of the upper unit and a more continental source of the tsunamite cap which includes c n 10 and the presence of inner shelf foraminifera with a lack of abyssal species this interpretation is in agreement with the lack of a tsunamite cap for the turbidite likely linked to the ad 1542 historic earthquake that is not associated with a tsunami the new sedimentologic criteria identifies the final seiche and tsunamite cap deposits of sts and provides a model that can now be tested in other locations to better understand the different depositional processes of seismo turbidites in confined basins

offshore sedimentary effects of the 12 january 2010 haiti earthquake although the 12 january 2010 haiti earthquake was one of the deadliest earthquakes in history it left no clear geological evidence of rupture on land as a tectonic event the earthquake was complex even the faults involved remain unclear using geophysical and coring data we document direct evidence of the sedimentation generated by the catastrophic 12 january 2010 earthquake offshore these studies document submarine paleoseismology methods that can be used for assessing seismic risk in this and other tectonic settings such as the california san andreas fault where deeper buried blind thrusts may exist shaking by the 12 january main shock triggered sediment failures and turbidity currents from coastal sources to deep water sinks an 0 05 km 3 turbidite was deposited in the canal du sud basin 1750 m water depth over 50 km 2 almost 2 months after the main shock a 600 m thick sediment plume was still present in the lowermost water column at this location the turbidite was time correlated to the 12 january earthquake by the excess 234 th in the sediments with a half life of 24 days its presence documents an infl ux of terrigenous sediment mixing with marine sources derived from the basin slopes this turbidite and older ones observed beneath it displays complex cross bedded and fi ning upward stratigraphy indicative of long waves and seiche oscillations that are consistent with locally reported tsunamis this 12 january sedimentary record highlights the potential for submarine paleoseismology to unravel the seismic history of continental transform boundaries such as the enriquillo plantain garden fault in the dominican republic haiti and jamaica as well as other tectonic settings where no clear land based evidence for a rupture exists

comment on lost tsunami by maria teresa pareschi et al a numerical simulation recently published bypareschi et al 2006a hereinafter referred to aspar2006 suggests the possible occurrence of a majortsunami that should have hit the eastern mediterranean inthe early holocene the catastrophic collapse of the easternflank of the etna volcano that formed the valle del bove calvari and groppelli 1996 calvari et al 1998 isreported as the trigger of this tsunami that generated apelagic turbidite nicknamed homogenite kastens andcita 1981 or augias turbidite cita et al 1984 hieke 1984 throughout the eastern mediterranean since itsdiscovery this deposit characterized by an acousticallytransparent facies on seismic profiles has been related tothe 3500 years old collapse of the santorini caldera kastens and cita 1981 several papers published in thelast 25 years followed this interpretation see cita andrimoldi 2005 and references therein so there is a generalagreement about the tsunamigenic origin for the widespreadhomogenite deposits while a big discrepancy exists be tween the timing of this event and the formation of the valledel bove which cannot be younger than 7600 calibrated yr b p calvari and groppelli 1996

eocene paleoseismic record of the green river formation fossil basin wyoming u s a implications of synsedimentary deformation structures in lacustrine carbonate mudstones abstract laterally extensive intervals containing sedimentary deformation features are identified in outcrops of lacustrine deposits of the eocene 52 51 ma green river formation in fossil basin southwestern wyoming fossil basin is the smallest of the paleo lakes in the green river system and is located in the sevier fold and thrust belt which was tectonically active during deposition deformation structures include convolute lamination load structures hybrid brittle ductile features sedimentary dikes microfaults fluid escape features such as cusps and pipes oil shale breccias and mass transport deposits in most cases these structures are hosted by finely laminated variably organic rich carbonate mudstones that accumulated in a low energy profundal lacustrine environment deformed intervals range from a few centimeters to 5 m in thickness and are bound above and below by undeformed strata of the same facies which demonstrates the early post depositional timing of deformation the distribution of these features indicates a primary control exerted by sediment rheology resulting from variation in grain size clay and organic content and degree of lithification which in turn were governed by the depositional environment and early diagenesis based on their morphological attributes lateral extent and recurrence at different stratigraphic levels along with their sedimentary environment and the tectonic setting of the basin the deformation structures are interpreted to be seismites i e the result of stresses induced by syndepositional earthquakes and other potential trigger agents are rejected moreover stratigraphic relationships indicate that these small scale deformation features as well as the mass transport deposits formed on a virtually flat lake floor ruling out instability caused by the gravitational regime syndepositional deformation in fossil basin points to tectonic activity along the nearby absaroka and or hogsback thrusts and related fault systems seismites point to possible tectonic forcing as a mechanism for changes in bathymetry and sedimentation in the green river formation and consequently demonstrate their potential for elucidating the tectonic history of other lacustrine and marine basins

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

tsunami and seiche triggered deformation within offshore sediments abstract most studies of tsunami and seiche related deposits have focussed on coastal and near coastal zones which are most readily accessible with few investigations of deeper water settings and the potential soft sediment deformation effects of such waves the late pleistocene lisan formation outcropping to the west of the dead sea contains superb examples of sedimentary slump folds formed in water depths of

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

stratigraphy and sedimentation in the western strabo trench eastern mediterranean abstract three piston cores ranging in length from 501 to 921 cm raised from the adjacent mediterranean tyro and kretheus basins and their intervening sill confirmed previous findings of persistent anoxia and extended our knowledge of the stratigraphic record the two cores from the basinal settings contain a bronze age homogenite this tsunami induced turbidite is only 28 cm thick in the shallower kretheus basin whereas it has a thickness of 235 cm in the deeper tyro basin the recovery of the homogenite in these subbasins of the western strabo trench demonstrates that the tsunami wave turned west of crete and arrived here with a velocity sufficient to remobilize unconsolidated sediments draping the basin slopes the holocene and uppermost pleistocene sedimentary record is characterized by numerous millimetric to centimetric sand layers containing reworked pliocene and miocene foraminifers the repetitive siliciclastic turbidites interfered with the normal eastern mediterranean succession of sapropels and tephras and document a strong neotectonic activity related to the presence of an active trench on the floor of ponded rimmed basins like the tyro and kretheus basins the sand layers are associated with anoxic sediments whereas they are associated with normal well oxygenated marls on the sill which lies above the anoxic oxic interface basin anoxia is interpreted as the result of submarine dissolution of messinian evaporites giving rise to deep seated brines extraformational reworking documents the occurrence of pre messinian fossiliferous sediments exposed on the trench wall and subject to submarine erosion the stratigraphic time framework is given by nannofossil biostratigraphy corroborated by lithostratigraphic correlation of isochronous lithologies sapropel and tephra chronology a drastic change in sedimentary regime is recorded at approximately 70 ka b p emiliania huxleyi acme e huxleyi zonal boundary older sediments which were only recovered in core 37 from the sill separating the tyro and kretheus basins are pelagic with an almost typical eastern mediterranean succession of sapropels and tephras no siliciclastic turbidites and no extraformational reworking are noticed in sediments older than 70 000 years we conclude that the trench system became active just at that time a thick layer of plurimillimetric pumice bubbles was discovered within sapropel s 6 indicating a strong explosion of a nearby volcano at 180 ka b p but we have no analytical data yet to substantiate the provenance of the volcanogenic deposits

late quaternary co seismic sedimentation in the sea of marmara s deep basins the deep northern part of the sea of marmara northwestern turkey is composed of several aligned actively subsiding basins which are the direct structural and morphological expression of the north anatolian fault s northern branch the last 20 kyr of their sedimentary fill lacustrine before 12 kyr bp have been investigated through giant piston coring onboard r v marion dufresne marmacore cruise 2001 and chirp subbottom profiler onboard r v atalante during marmarascarps cruise 2002 especially during the lacustrine stage the infilling of the deep basins tekirda central kumburgaz and cinarcic basins up to 1250 m depth was dominated by turbidites with coarse mixed siliciclastic and bioclastic basal part intercalated in hemipelagic type finegrained calcareous and slightly siliceous clays often especially in the thickest ones the turbidites show strong segregation and a sharp boundary between coarse part and suspendedload part in the central basin 8 m of a unique sedimentary event include a 5 to 8m thick homogenite well imaged on seismic profiles the latter is interpreted as related to a major possibly triggered tsunami effect as described in the eastern mediterranean by kastens and cita 1981 in the marine holocene upper part of the sedimentary fill repeated to and from structures affecting silt or fine sand are evidencing seiche like effects and thus earthquake triggering detailed correlations between two deep coring sites 1250 and 1200 m indicate more than 100 overthickening in the deepest one this implies specific processes of distribution of terrigenous input by dense hyperpycnal currents high kinetic energy seiche effect complex reflections on steep slopes the peculiar sedimentary infilling of the sea of marmara s central basin and by extrapolation of the whole set is tentatively interpreted as a direct consequence of the strong seismic activity the imprint of the latter is more obvious prior to the base of the holocene as environmental conditions favoured marginal accumulation especially on the southern shelf of large amounts of erosion products available for mass wasting

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

genesis of limestone megabreccias and their significance in carbonate sequence stratigraphic models a review a re appraisal of the factors controlling the deposition of carbonate megabreccias and their sequence stratigraphic significance is presented based on an examination of the mechanisms for instigating carbonate seafloor slope instability and a review of the depositional settings of these distinctive rock deposits limestone megabreccias have classically been interpreted as formed by the catastrophic collapse of high angle metastable oversteepened carbonate platform margins however a review of megabreccia occurrence shows that these deposits formed on a broad range of carbonate slope angles and that metastable oversteepened slopes are not necessary for their genesis a re evaluation constructed from first principles of mechanisms promoting submarine gravitational instability indicates that pore water overpressure of confined aquifer horizons beneath the seafloor rather than slope oversteepening is the critical control on megabreccia deposition catastrophic release of overpressure may initiate gravitational instability of previously kinematically stable slopes the relative importance of endogenic processes intrinsically linked to the depositional system and exogenic processes operating independently in generating megabreccias is assessed two particularly important mechanisms in generating megabreccias are endogenic processes causing overpressure at discrete hydrologically confined horizons beneath the seafloor during relative sea level falls and increases in stress as pore fluid drains from the sediment when the platform top becomes subaerially exposed during relative lowstands of sea level the increased likelihood of megabreccia genesis during relative sea level falls is supported by an empirical trend identified from a review of the stratigraphic distribution of documented megabreccias exogenic causes of gravitational instability with inherently random periodicity especially seismicity may account for the small number of documented megabreccias that do not conform to this underlying trend the proposed endogenic pattern favouring megabreccia deposition during relative sea level falls is important in a sequence stratigraphic context megabreccia deposits may build volumetrically significant toe of slope wedges and aprons during relative lowstands of sea level partially compensating for the decrease loss in the supply of fresh granular sediment as the platform top carbonate factory contracts lowstand wedges and aprons in carbonate systems therefore generally differ in composition from equivalent highstand deposits in being composed not of calciturbidite deposits but of megabreccias cannibalized from the upper slope

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

evidence for ocean water invasion into the chicxulub crater at the cretaceous tertiary boundary the possibility of ocean water invasion into the chicxulub crater following the impact at the cretaceous tertiary boundary was investigated based on examination of an impactite between approximately 794 63 and 894 94 m in the yaxcopoil 1 yax 1 core the presence of cross lamination in the uppermost part of the impactite suggests the influence of an ocean current at least during the sedimentation of this interval abundant occurrence of nannofossils of late campanian to early maastrichtian age in the matrices of samples from the upper part of the impactite suggests that the carbonate sediments deposited on the inner rim margin and outside the crater were eroded and transported into the crater most likely by ocean water that invaded the crater after its formation the maximum grain size of limestone lithics and vesicular melt fragments and grain and bulk chemical compositions show a cyclic variation in the upper part of the impactite the upward fining grain size and the absence of erosional contact at the base of each cycle suggest that the sediments were derived from resuspension of units elsewhere in the crater most likely by high energy currents association with ocean water invasion

transparent layers in seismic reflection records from the central ionian sea mediterranean evidence for repeated catastrophic turbidite sedimentation during the quaternary abstract echosounding and scs records from the ionian and sirte abyssal plains show below the holocene augias megaturbidite two additional thick transparent layers which by analogy are interpreted as turbidites estimated thicknesses are 10 and 35 m upper and lower as a minimum no consideration of presumable variations of acoustic velocities the resulting sediment volumes are about 26 and about 200 km 3 respectively both layers occupy the entire abyssal plain basins similar to the holocene augias megaturbidite a provenance of mobilized sediments from the gulf of sirte into the basins is assumed the ages of the two turbidites have been estimated at 235 000 and 650 000 years respectively it is speculated that mobilization was triggered by tsunamis related to volcanic events or earthquakes in the southern aegean region