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

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

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

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

reading of the trigger records of sedimentary events a problem for future studies abstract sedimentary records of various three to four dimensional patterns of nature have recently attracted the special attention of many geologists the dramatic development of rhythmic sequence stratigraphy is a conspicuous recent instance the significance of event sedimentation in geohistory however has not been examined sufficiently the problem to how to read the records of triggers or thresholds of sedimentary events has been ignored the difficulty of solving this problem concerns the difference in patterns between natural sedimentary processes and their resulting sediments terminological confusion of event deposits is another cause which hinders our taking note of this problem a few examples of endeavours to discriminate the threshold of sedimentary events are shown by the analysis of two kinds of turbidites of the mid guatemala trench the investigation of slump derived turbidites of the suruga trough and the study of the seismoturbidites in lake biwa well focused investigations of features of trigger known sediments is the best strategy to find the criteria for discriminating the triggers or thresholds based on sedimentary records of various sedimentary events from this point of view more detailed studies of the santorini eruption induced homogenites the k t boundary impact induced tsunamiites together with the lake biwa seismic turbidites are very important further efforts should be made to find and investigate as many trigger identifiable sediments as possible

observations on the distribution and characteristics of potholes on surging glaciers potholes are depressions often water filled 10 100 m across found on the surfaces of glaciers most fields of potholes are found on surging glaciers suggesting that potholes form as a result of surging a photographic inventory of hundreds of glaciers in alaska and yukon territory allowed this hypothesis to be tested out of 26 pothole fields observed 19 were on known surging glaciers two on probable surging glaciers and the rest in areas where surging glaciers are common the majority of pothole fields were found near the equilibrium line photographs show that potholes formed within several years following the 1937 surge of the black rapids glacier in a zone where there had been intense crevassing between 1949 and 1986 the total number of potholes on the glacier decreased from approximately 700 to less than 200 while their mean size increased from 20 to 30 m some of these potholes have been observed to drain englacially the movement of these potholes were measured photogrammetrically to be less than 10 m yr the majority of the motion resulting from ice flow intense crevassing resulting from surging appears to be necessary for the formation of potholes but not sufficient as only 21 out of 256 surging glaciers contain potholes

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

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

source of the 1693 catania earthquake and tsunami southern italy new evidence from tsunami modeling of a locked subduction fault plane 1 the 1693 catania earthquake which caused 60000 deaths in eastern sicily and generated a 5 10 m high tsunami is investigated gps data indicate ese wnw convergence in the calabrian arc at 4 5 mm yr new high resolution seismic data image active compression at the toe of the accretionary wedge the lack of instrumentally recorded thrust earthquakes suggests the presence of a locked subduction fault plane thermal modeling is applied to calculate the limits of the seismogenic zone tsunami modeling is performed to test the hypothesis that the 1693 earthquake occurred on the subduction fault plane 160 120 km in size with 2 m of mean co seismic slip this source successfully reproduces historical observations with regard to polarity and predicts 1 3 m high amplitudes it is likely that only the sw segment of the subduction fault plane ruptured in 1693 and 1169 implying a recurrence interval of roughly 500 years for similar events

mud redeposition and problems of assessing microfossil isotopic and radiocarbon data in the mediterranean abstract a literature review of mediterranean margin and basin stratigraphy indicates that most sampling for microfossil isotopic and radiocarbon age data is performed on finegrained sediments comprehensive petrologic analyses of suites of cores collected in different mediterranean slope basin plain systems indicate that at least two thirds of the muds of pliocene and quaternary age were emplaced by downslope directed mass flow and related sediment gravity flows such as mud carrying turbidity currents rather than by suspension settling hemipelagic rain mechanisms not surprisingly microfossil and isotopic studies undertaken without detailed petrologic examination of sampled mud sections have led to some spurious interpretations sedimentological surveys in most of the mediterranean sectors indicate that episodic redepositional events have disturbed the sedimentary record sufficiently to produce discontinuity of strata complicate regional litho and biostratigraphic correlations and seriously confuse paleoecological assessment radiocarbon dates also remain suspect unless it is demonstrated that the dated organic matter usually microfossils is not of downslope displaced origin but rather primarily by suspension settling to the seafloor it is essential therefore to test for the reworking factor as a consequence of important local influences such as physiographic configuration and accessibility to sediment sources and dispersal paths as well as transport mechanisms reliability of interpretations is enhanced by closely coupling biostratigraphic with sedimentological analyses

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

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

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

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

depositional mechanisms for upper miocene sediments in the south china sea central basin evidence from calcareous nannofossils abstract in 2014 the international ocean discovery program iodp expedition exp 349 discovered carbonate layers at sites located in the south china sea scs central basin preliminary results from shipboard investigation showed that most of these carbonate layers are calcareous nannofossil ooze and interpreted them as turbidites however more detailed studies are required to determine their depositional mechanisms and paleoenvironmental implications in this study we have analyzed caco3 content calcareous nannofossil abundance assemblage composition and preservation in carbonate and clay samples from the upper miocene sections of site u1433 in the scs central basin we confirm that these carbonate layers are of turbidity current genesis but are not typical nannofossil ooze while the clays represent regular in situ deep sea sediments the study interval spanned approximately from 10 to 5 million years before present ma calcareous nannofossil abundance and assemblage are used to reconstruct the evolution of the upper seawater structure in the scs central basin our results indicate that the seawater shifted from strongly stratified to well mixed due to enhanced monsoon this shift was accompanied by an increase in pelagic productivity at 8 ma this environmental change is critical for component variations of the carbonate turbidites since we suggest that these turbidites mainly sourced from periplatform ooze in the southern scs composed by of mixed neritic and pelagic particles the neritic and pelagic caco3 production have inversed responses to the change of seawater environment in the scs and thus cause the component variations in the carbonate turbidites of site u1433

varve calibrated records of carbonate and organic carbon accumulation over the last 2000 years in the black sea sedimentologic and geochemical studies of box and gravity cores recovered from the black sea during the first leg of a multileg international black sea expedition in 1988 allow reconstruction of the basinwide holocene environmental history of the black sea in the deeper parts of the basin box cores typically recovered a flocculent surface layer fluff laminated coccolith marls of unit i 25 45 cm thick and the upper 5 10 cm of finely laminated dark colored sapropels of unit ii fine grained homogeneous mud turbidites are interbedded with units i and ii over much of the basin but the stratigraphie position of these turbidites differs from site to site the deposition of individual turbidites up to 15 cm thick does not appear to have significantly disturbed underlying laminae sediment trap deployments in the black sea suggest that light and dark laminae couplets represent annual increments of sedimentation i e varves we have therefore constructed a varve chronology for the sequence in order to correlate and date distinctive sedimentation and paleoenvironmental events distinctive groups of laminae in unit i can be correlated across the entire deeper basin a distance of more than 1000 km this implies a remarkable homogeneity in production accumulation and preservation of biogenic material over much of the black sea during deposition of unit i the change from deposition of finely laminated organic carbon rich sapropels unit ii to laminated more calcareous coccolith rich marls unit i is thought to represent the crossing of a salinity threshold for emiliania huxleyi the varve chronology sets this change at about 1 63 ka 1633 100 yr b p but the record of magnetic secular variation measured in several cores produces an age estimate of about 2 0 ka for the base of unit i or about 1 2 times the varve age the average of six calibrated accelerator mass spectrometry radiocarbon ages for the base of unit i is 2 7 ka or about 1 7 times the varve age following the initial change to coccolith dominated sedimentation deposition of sapropel resumed for at least one significant period 1 56 1 25 ka since 1 25 ka cycles of carbonate deposition with quasi decadal periodicities have produced characteristic darker and lighter assemblages of laminae these cycles may have been climatically driven geochemical analyses coupled with the varve ages adopted herein indicate that accumulation rates of carbonate are nearly an order of magnitude higher in unit i averaging 35 45 g m 2 yr 1 than in sapropelic unit ii which contains primarily detrital carbonate the accumulation of lithogenic components in parts of unit i is only 1 5 times the rate in unit ii deepwater organic carbon accumulation rates are somewhat higher in unit i 3 5 4 5 g m 2 yr 1 than in the upper part of unit ii organic carbon accumulation rates in unit i are somewhat antithetic to those of carbonate and on the basis of this and additional constraints placed by pyrolysis and carbon isotopic analyses of organic material it appears that terrestrial organic matter is an important component perhaps 25 of total organic carbon burial in the basin unit i in the western part of the black sea has a higher terrestrial organic component and higher accumulation rates of terrigenous clastic material than unit i in the eastern part this difference between eastern and western black sea is to be expected because of the major rivers that empty into the western black sea from eastern europe ukraine and russia shallow slope sites but still within euxinic bottom waters have lower organic carbon accumulation rates and lower pyrolysis hydrogen indices than deepwater basinal sites suggesting selective resuspension and oxidation of organic matter at basin margins and focusing of organic matter deposition toward the basin center a comparison of the black sea data with those from several open ocean sites with similar water depths showed no significant difference between organic carbon accumulation rates under oxic and anoxic conditions for a given bulk accumulation rate the organic carbon accumulation rates normalized to primary productivity are about the same in both settings

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 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

mesoscale and microscale structure of cirrus clouds three case studies abstract the structure and composition of three basic cirrus cloud types are examined through coordinated aircraft and ground based polarization lidar and radar measurements the cloud systems consist of a multilayered orographic cirrus a 6 km deep cirrostratus and a group of fibrous cirrus bands at the tropopause the data reveal the presence of mesoscale generating regions with horizontal dimensions ranging from 15 km in narrow cloud bands up to 100 km in cirrostratus these generating regions appear to be composed of complexes of much smaller convective structures presumably on the 1 km scale of cirrus uncinus cells and so are termed mesoscale uncinus complexes muc accumulations of ice particles within cirrus commonly referred to as precipitation trails are associated with generating regions at or near cloud tops but are also created by the local production of ice crystals within embedded convective impulses supercooled cloud droplets large enough to be detected by aircraft probes 5 m

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

gelatinous pellicles in deep anoxic hypersaline basins from the eastern mediterranean abstract gelatinous pellicles have been observed in three out of ten cores recovered from the bannock basin or bacino bannock and in two dredges from its flanks during a cruise of the r v bannock in the eastern mediterranean similar pellicles have also been detected in two cores recovered from the tyro basin the bannock and tyro basins are brine filled depressions which are presently characterized by anoxic sedimentation in the bannock basin also gypsum precipitation occurs the gelatinous pellicles some millimeters thick and dark grey to greenish in color are always found in very dark colored sediments of quaternary age these pellicles have been investigated by optical microscopy by scanning electron and transmission electron microscopy and by flash pyrolysis gas chromatography and flash pyrolysis gas chromatography mass spectrometry to decipher their nature abundant skeletal tests of siliceous and calcareous planktonic organisms radiolaria diatoms silicoflagellates formainifera and nannofossils are observed together with amorphous organic matter the pellicles enclosing these remains consist of organic matter they foliate into submillimetric undulating and anastomosing microlaminae cellular structures are never observed neither in the pellicles nor in the microlaminae organic geochemical analyses point to a high contribution of terrestrial material the organic matter of the pellicles investigated consists of a coal like material it is suggested that the pellicles are originally formed at the brine seawater interface but subsequently sink to the bottom due to increasing load of entrapped biogenic and non biogenic detritus

landsat based inventory of glaciers in western canada 1985 2005 abstract we report on a glacier inventory for the canadian cordillera south of 60 n across the two western provinces of british columbia and alberta containing 30 000 km2 of glacierized terrain our semi automated method extracted glacier extents from landsat thematic mapper tm scenes for 2005 and 2000 using a band ratio tm3 tm5 we compared these extents with glacier cover for the mid 1980s from high altitude aerial photography for british columbia and from landsat tm imagery for alberta a 25 m digital elevation model dem helped to identify debris covered ice and to split the glaciers into their respective drainage basins the estimated mapping errors are 3 4 and arise primarily from seasonal snow cover glaciers in british columbia and alberta respectively lost 10 8 3 8 and 25 4 4 1 of their area over the period 1985 2005 the region wide annual shrinkage rate of 0 55 a 1 is comparable to rates reported for other mountain ranges in the late twentieth century least glacierized mountain ranges with smaller glaciers lost the largest fraction of ice cover the highest relative ice loss in british columbia 24 0 4 6 occurred in the northern interior ranges while glaciers in the northern coast mountains declined least 7 7 3 4

the new remote sensing derived swiss glacier inventory ii first results complete swiss glacier inventories are available for 1850 reconstructed and 1973 from aerial photography connected to the global land ice measurements from space project a new swiss glacier inventory for approximately the year 2000 sgi 2000 is compiled mainly based on satellite imagery the developed and applied remotesensing and geographical information system gis methods are described in part i of the contribution in part ii the inventory design first result analyses and comparisons with former glacial conditions are presented as basic entries sgi 2000 contains the individual glacier identification planimetric glacier boundaries as derived from image analysis digitized central flowlines and polygonal glacier basin maps all other parameters are automatically deduced from the above entries and a digital elevation model within a gis here we analyze a set of small bernese and valais glaciers of area 2 these glaciers lost about 21 of area from 1973 to 1998 in addition to about 80 during 1850 1973 both with respect to the 1973 area in order to track the latest trend in more detail anintermediate glacier condition has been compiled from satellite imagery of 1985 this analysis gave an increasing speed of area loss 19 for 1985 98

sheet gravel evidence for a late holocene tsunami run up on beach dunes great barrier island new zealand abstract a semi continuous sheet of granule to cobble size clasts forms a distinctive deposit on sand dunes located on a coastal barrier in whangapoua bay great barrier island new zealand the gravel sheet extends from the toe of the foredune to 14 3 m above mean sea level and 200 m landward from the beach clasts are rounded to sub rounded and comprise lithologies consistent with local bedrock terrestrial sources for the gravel are considered highly unlikely due to the isolation of the dunes from hillslopes and streams the only source for the clasts is the nearshore to inner shelf of whangapoua bay where gravel sediments have been previously documented the mechanism for transport of the gravel is unlikely to be storm surge due to the elevation of the deposit maximum recorded storm surge on this coast is 0 8 m above mean high water spring tide aeolian processes are also discounted due to the size of clasts and the elevation at which they occur tsunami is therefore considered the most probable mechanism for gravel transport minimum run up height of the tsunami was 14 3 m based on maximum elevation of gravel deposits optical ages on dune sands beneath and covering the gravel allow age bracketing to 0 4 7 ka within this time frame numerous documented regional seismic and volcanic events could have generated the tsunami notably submarine volcanism along the southern kermadec arc to the east southeast of great barrier island where large magnitude events are documented for the late holocene radiocarbon ages on shell from maori middens that appear to have been reworked by tsunami run up constrain the age of this event to post ca 1400 ad regardless of the precise age of this event the well preserved nature of the whangapoua gravel deposit provides for an improved understanding of the high degree of spatial variability in tsunami run up

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

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

tsunami generated by the late bronze age eruption of thera santorini greece tsunami were generated during the late bronze age lba eruption of the island of thera in the southern aegean sea by both caldera collapse and by the entry of pyroclastic surges flows and lahars debris flows into the sea tsunami generated by caldera collapse propagated to the west producing deep sea sedimentary deposits in the eastern mediterranean sea known as homogenites open ocean wave heights of about 1 9 17 m are estimated tsunami generated by the entry of pyroclastic flows surges and lahars debris flows into the sea propagated in all directions around the island wave heights along coastal areas were about 7 12 m as estimated from newly identified tsunami deposits on eastern thera as well as from pumice deposits found at archaeological sites on northern and eastern crete

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

turbidite flux architecture and chemostratigraphy of the herodotus basin levantine sea se mediterranean the herodotus basin is the deepest part of the se mediterranean and receives allochthonous sediments as turbidity currents and debris flows from around its margin during the late quaternary characteristic supply has been from at least four sources these are 1 dark coloured calcium carbonate poor fine grained turbidites derived from the nile cone to the south and south east 2 lighter coloured calcium carbonate rich slightly coarser grained turbidites derived from the libyan egyptian shelf to the south 3 small light brown foraminifer rich muddy silty turbidites derived from the cyprus eratosthenes seamount anatolian rise carbonate shelf to the east and 4 small localized debris flow deposits derived from the mediterranean ridge to the north during the late quaternary 0 60 ka and specifically the period of 0 27 ka the basin has filled predominantly with allochthonous material derived from the nile cone although one megaturbidite of basinwide extent was derived from the libyan egyptian shelf turbidites have been correlated across the herodotus basin using the technique of chemostratigraphy matching the results of geochemical analysis may show whether or not the beds in different cores were deposited by the same mass wasting event for individual turbidites commonly have diagnostic and unique geochemical fingerprints in terms of major minor and trace element composition sediment budgets for the three main turbidite sources are calculated the cumulative volume of the sedimentary input for the nile cone derived turbidites over the last 27 ka is c 500 km3 giving an average sedimentation rate of c 45 cm ka 1 and a volume per unit time of 18 km3 ka 1 a megaturbidite derived from the libyan egyptian shelf is of basinwide extent and has a volume of c 400 km3

the 27 28 october 1986 fire cirrus case study meteorology and clouds abstract detailed descriptions of the rawinsonde resolved meteorological conditions 3 hourly soundings associated with a succession of five distinct mesoscale cirrus cloud regimes which were observed intensely over a 36 hour period is given the synoptic scale systems in which these features were embedded are described and a brief overview of the experiment are given regional analyses of the static stability structure and vertical motion are presented and interpreted with respect to the characteristics of the corresponding cloud fields as deduced from satellite and lidar observations the cloud fields exhibited a high degree of persistent mesoscale organization on scales of 20 500 km reflecting corresponding scales of dynamic and thermodynamic structure variability as on the synoptic scale cloud generation was usually confined to layers less than 1 km deep typically 0 5 km in depth and cellular organization was evident in most cases irrespective of the thermal stratification multilayered developm

turbidites and megaturbidites from the herodotus abyssal plain eastern mediterranean unrelated to seismic events abstract a transect of 9 piston and gravity cores was taken across the southeast flank of the mediterranean ridge the transect extends from the abyssal plain to a location 290 m shallower than the abyssal plain and 50 km north of the edge of the ridge each core contains two or more turbiditic layers which belong to two discrete types here called a and b type a essentially consists of black plastic clays rich in smectite with silt fraction of terrigenous nature source area is the nile cone and age is middle or late pleistocene type b turbidites are pale brown to whitish in color coarse grained carbonate rich and bioclastic in composition with shallow water fossils dominant they are poor in smectite and the silt fraction is very rich in carbonates calcite and aragonite the source area is the north african shelf south of the abyssal plain a megabed belonging to type b turbidites is correlatable from core to core with a thickness in excess of 10 m in the abyssal plain and an estimated volume of 10 km 3 its stratigraphic position in the latest pleistocene suggests that its origin is related to a sudden collapse of bioclastic sediments accumulated in a canyon head during a low sea level stand the source areas of the two discrete turbidite types belong to the essentially aseismic north african continental margin although they are presently recorded on the tectonically active mediterranean ridge no seismic events are required to account for the presence of either type of turbidite

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

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

influence of sea level and basin physiography on emplacement of the late pleistocene herodotus basin megaturbidite se mediterranean sea radiocarbon 14c dates from pelagic intervals above a megaturbidite in the herodotus basin give direct evidence of emplacement at the beginning of the last glacial period approximately 27 125 calendar years before present as sea level lowered rapidly and entered a low stand phase the herodotus basin megaturbidite is a basinwide deposit that forms a recognisable acoustically transparent layer on 3 5 khz high resolution seismic profiles and covers an area of approximately 40 000 km2 it thins from about 20 m in thickness proximally to some 10 m distally over a basin length in excess of 400 km the total volume is estimated at around 400 km3 which is significantly more than the volume of sediment that could have been displaced from its most likely source area the funnel shaped marginal embayment of the gulf of salum to the west of the nile cone the additional material may have been derived in part from synchronous failures on other parts of the libyan egyptian shelf and slope but most is believed to have come from large scale erosion at the base of the very large volume turbidity current that was generated from the original slide detailed sedimentary analyses of cores recovered from the megaturbidite show its distinctive characteristics graded sand silt mud and bioturbated mud units poorly developed structures proximally becoming more distinct and ordered distally variation in grain size and structures that suggest either flow separation reflection around topographic highs and or an inherently unstable flow and a mixed source bioclastic terrigenous composition these features together with its size and lateral extent would make any similar megabed an excellent marker horizon in basin analysis a combination of factors was responsible for triggering the initial slide debris flow event that evolved downslope into this mega turbidity current these include lowered sea level that destabilised the outer shelf upper slope sediments tectonic oversteepening of the margin relatively high rates of sedimentation and seismic activity

geoarchaeological tsunami deposits at palaikastro crete and the late minoan ia eruption of santorini abstract the explosive eruption at santorini in the aegean sea during the second millennium bce was the largest holocene volcanic upheaval in the eastern mediterranean region the eruption was disastrous for the minoan settlements at santorini but the effect on human society in the neighbouring islands and regions is still clouded in uncertainty tsunami generation was suggested but comparatively little evidence was found the lack of firm tsunami traces is particularly puzzling in crete with its coastal settlements of the late minoan ia period during which the santorini eruption occurred here we report the discovery of extensive geoarchaeological tsunami deposits at palaikastro in north eastern crete these deposits are characterized by a mixture of geological materials including volcanic santorini ash and archaeological settlement debris various tsunami signatures were identified 1 erosional contact with the underlying strata 2 volcanic ash intraclasts in the lower part of the deposit 3 reworked building stone material in the lower part of the deposit 4 individual marine shells 5 marine micro fauna 6 imbrication of rounded beach pebbles settlement debris ceramic sherds and even bones 7 multi modal chaotic composition late minoan human settlement activities at palaikastro provided architectural and stratigraphic frameworks in space and time that recorded and preserved tsunami evidence as geoarchaeological deposits such stratigraphic resolution and preservation may not occur in the natural landscape volcanic ash transported by wind from santorini south east to crete preceded the tsunami geological archaeological and radiocarbon dating criteria all converge indicating that the tsunami deposits are coeval with the minoan santorini eruption field evidence suggests that tsunami waves at palaikastro were at least 9 m high inverse tsunami modeling was attempted based on these newly discovered tsunamigenic deposits the initial wave in the generation region at santorini that best fits the stratigraphic data is a wave with 35 to 15 m initial amplitude and a crest length of about 15 km

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

how much do we really know about glacier surging some of the ideas about glacier surging are considered mainly but not entirely in the light of observations of temperate glaciers in alaska u s a made within the last 15 years climate has an influence on surge recurrence interval climate and weather also affect surge initiation termination and magnitude regional studies lead to the speculation that subglacial till plays a key role in surging and it has been found under all surge type glaciers studied so far including black rapids and variegated glaciers alaska in most of the glaciers studied till deformation processes dominate the motion in quiescence the linked cavity model of surge triggering and rapid motion is not consistent with these observations but the limited coverage of the observations does not rule it out under parts of the glaciers studied the till observations in alaska raise old questions about the interaction between till and the hydraulic systems of temperate glaciers the role of stored water which observations show to be active even in winter on black rapids glacier is noted

glacier velocities across the central karakoram optical matching of aster advanced spaceborne thermal emission and reflection radiometer satellite image pairs is used to determine the surface velocities of major glaciers across the central karakoram the aster images were acquired in 2006 and 2007 and cover a 60 120 km region over baltoro glacier pakistan and areas to the north and west the surface velocities were compared with differential global position system gps data collected on baltoro glacier in summer 2005 the aster measurements reveal fine details about ice dynamics in this region for example glaciers are found to be active over their termini even where they are very heavily debris covered the characteristics of several surge type glaciers were measured with terminus advances of several hundred meters per year and the displacement of trunk glaciers as surge glaciers pushed into them this study is the first synthesis of glacier velocities across this region and provides a baseline against which both past and future changes can be compared

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

the 2008 09 surge of central yulinchuan glacier northern tibetan plateau as monitored by remote sensing the 2008 09 surge of central yulinchuan glacier cyg on the northwestern slope of muztag mountain tibetan plateau is studied based on satellite remote sensing the widely used cross correlation feature tracking method was used to collect satellite image control points and validate their geometric accuracies as well as to derive glacier surface velocity changes in glacier length and area were also retrieved results show that the surge of cyg initiated in may 2008 and terminated in july 2009 two diffluent glacier termini advanced 590 26 m 5 1 0 2 of the 2004 length and 182 26 m 1 8 0 3 respectively and glacier area increased by similar to 1 41 0 11 km 2 4 6 0 4 of the 2004 area during this period the most significant surge period was october 2008 to march 2009 when most of the terminus advances and area increases occurred the glacier surface drastically crevassed during this time as much as 1657 297 m of horizontal surface displacements were produced by surge ice and maximum surface speed reached 13 1 5 m d 1 results of transverse and longitudinal velocity profiles revealed two surge waves during this surge of cyg

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

the new remote sensing derived swiss glacier inventory i methods a new swiss glacier inventory is to be compiled from satellite data for the year 2000 the study presented here describes two major tasks 1 an accuracy assessment of different methods for glacier classification with landsat thematic mapper tm data and a digital elevation model dem 2 the geographical information system gis based methods for automatic extraction of individual glaciers from classified satellite data and the computation of three dimensional glacier parameters such as minimum maximum and median elevation or slope and orientation by fusion with a dem first results obtained by these methods are presented in part ii of this paper kaab and others 2002 thresholding of a ratio image from tm4 and tm5 reveals the best suited glacier map the computation of glacier parameters in a gis environment is efficient and suitable for worldwide application the methods developed contribute to the u s geological survey led global land ice measurements from space glims project which is currently compiling a global inventory of land ice masses within the framework of global glacier monitoring haeberli and others 2000

visible and near infrared digital images for determination of ice velocities and surface elevation during a surge on osbornebreen a tidewater glacier in svalbard

pleistocene suvero slide paola basin southern italy abstract the suvero slide covers an area of about 225 km 2 in the paola slope basin on the eastern tyrrhenian margin the shape and lateral extent of the deposit reflect topographic confinement of the slide between the continental slope and a morphologic barrier formed by a margin parallel slope ridge no headwall or slide plane comparable in scale with the slide deposit were found suggesting that quasi in situ deformation of semi consolidated sediments took place when the failed materials reached the floor of the slope basin the failure occurred downslope from a basement high originating from local uplift continued uplift after the suvero slide occurred is documented by the presence of steep upper slope gradients within the study area and by the presence of small scale creep and failure events that postdate the suvero slide

ice crystal shapes in cirrus clouds derived from polder adeos 1 this paper discusses the retrieval of ice crystal shapes of cirrus clouds on a global scale using observations collected with polder 1 polarization and directionality of the earth reflectance onboard the adeos 1 platform the retrieval is based on polarized bidirectional observations made by polder first normalized polarized radiances are simulated for cirrus clouds composed of ice crystals that differ in shape and are randomly oriented in space different values of cloud optical depths viewing geometries and solar zenith angles are used in the simulations this sensitivity study shows that the normalized polarized radiance is highly sensitive to the shape of the scatterers for specific viewing geometries and that it saturates after a few scattering events which makes it rapidly independent of the optical depth of the cirrus clouds next normalized polarized radiance observations obtained by polder have been selected based on suitable viewing geometries and on the occurrence of thick cirrus clouds composed of particles randomly oriented in space for various ice crystal shapes these observations are compared with calculated values pertaining to the same geometry in order to determine the shape that best reproduces the measurements the method is tested fully for the polder data collected on january 12 1997 thereafter it is applied to six periods of 6 days of observations obtained in january february march april may and june 1997 this study shows that the particle shape is highly variable with location and season and that polycrystals and hexagonal columns are dominant at low latitudes whereas hexagonal plates occur more frequently at high latitudes

sediment geochemistry of the thetis hypersaline anoxic basin eastern mediterranean sea abstract the thetis basin is a deep hypersaline anoxic basin in the western part of the mediterranean ridge eastern mediterranean sea it is characterised by highly sulphidic nacl saturated brine with one of the highest values of salinity reported from similar basins s 348 the strong pycnocline at the seawater brine interface induces permanent anoxic bottom conditions driving depositional processes and distribution patterns of redox sensitive metals in the sediments this work presents a high resolution dataset of sedimentological mineralogical and geochemical features and planktonic foraminifera distribution derived from the exploration of a 52 cm long box core sampled in the thetis sediments basing on direct comparisons with available data from other hypersaline records and ancient anoxic organic rich deep sea records sapropels and black shales we aim to explore the potential of these anoxic basins as natural laboratories to better understand the mechanisms driving geochemical patterns in recent ancient anoxic sediments

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

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

glacier surface velocities in alpine terrain from optical satellite imagery accuracy improvement and quality assessment the worldwide retreat of mountain glaciers has important consequences for the water food and power supply of large and densely populated areas in south and central asia successful mitigation of the hydrological impacts on societies as well as assessing glacier related hazards require large scale monitoring of glacier dynamics however detailed glaciological data from the asian highlands are lacking due to its size and difficult accessibility we have applied a novel technique for precise orthorectification co registration and sub pixel correlation of advanced spaceborne thermal emission and reflection radiometer aster satellite imagery to derive surface velocities of himalayan glaciers our approach allows for the correction of offsets due to attitude effects and sensor distortions as well as elevation errors if a digital elevation model dem from the shuttle radar topography mission srtm was used for orthorectification after post processing the error on the displacements is on the order of 2 4 m per correlation translated into annual velocities this error is reduced increased when the correlated images are more less than a year apart through application of a filtering procedure and several quality tests the consistency of the results is validated to provide confidence in the remotely sensed velocity measurements despite the lack of ground control this novel approach allows fast easy and economically viable acquisition of detailed glaciological data in areas of difficult access and provides a means for large scale monitoring of glaciers in high mountainous terrain

glacier surge mechanism 1982 1983 surge of variegated glacier alaska the hundredfold speedup in glacier motion in a surge of the kind the kind that took place in variegated glacier in 1982 1983 is caused by the buildup of high water pressure in the basal passageway system which is made possible by a fundamental and pervasive change in the geometry and water transport characteristics of this system the behavior of the glacier in surge has many remarkable features which can provide clues to a detailed theory of the surging process the surge mechanism is akin to a proposed mechanism of overthrust faulting

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

provenance of lithogenic surface sediments and pathways of riverine suspended matter in the eastern mediterranean sea evidence from 143nd 144nd and 87sr 86sr ratios in order to characterize the provenance of lithogenic surface sediments from the eastern mediterranean sea ems residual leached fraction of 34 surface samples have been analysed for their 143 nd 144 nd and 87 sr 86 sr isotope ratios the sample locations bracket all important entrances of riverine suspended matter into the ems as well as all sub basins of the ems the combined analyses of these two isotope ratios provide a precise characterization of the lithogenic fraction of surface sediments and record their dilution towards the central sub basins we reconstruct provenance and possible pathways of riverine dispersal and current redistribution assuming more or less homogenous isotopic signatures and flux rates of the eolian fraction over the ems lithogenic sediments entering the ionian sea from the calabrian arc and the adriatic sea are characterized by high 87 sr 86 sr isotope ratios and low end 0 values average 87 sr 86 sr 0 718005 and end 0 11 06 n 5 aegean sea terrigenous sediments show an average ratio of 87 sr 86 sr 0 713089 n 5 and values of end 0 7 89 n 5 the aegean isotopic signature is traceable up to the southwest south and southeast of crete the sediment loads entering the ems via the aegean sea are low and spread out mainly through the strait of casos east of crete surface sediments from the eastern levantine basin are marked by the highest end 0 values 3 3 n 6 and lowest 87 sr 86 sr isotope ratios average 0 709541 n 6 reflecting the predominant input of the nile sediment the influence of the nile sediment is traceable up to the ne trending eastern flank of the mediterranean ridge the characterization of the modern riverine dispersal and eolian flux based on isotope data may serve as a tool to reconstruct climate coupled variations of lithogenic sediment input into the ems d 2002 elsevier science b v all rights reserved

the composite characteristics of cirrus clouds bulk properties revealed by one year of continuous cloud radar data abstract the properties of midlatitude cirrus clouds are examined using one year of continuous vertically pointing millimeter wave cloud radar data collected at the atmospheric radiation measurement program southern great plains site in oklahoma the goal of this analysis is to present the cloud characteristics in a manner that will aid in the evaluation and improvement of cirrus parameterizations in large scale models using a temperature and radar reflectivity based definition of cirrus the occurrence frequency of cirrus the vertical location and thickness of cirrus layers and other fundamental statistics are examined also the bulk microphysical properties of optically thin cirrus layers that occur in isolation from other cloud layers are examined during 1997 it is found that cirrus were present 22 of the time had a mean layer thickness of 2 0 km and were most likely to occur in the 8 5 10 km height range on average the cirrus clouds tended to be found in layers in which the synoptic scale v

linking tsunami deposits submarine slides and offshore earthquakes abstract the recognition that many tsunamis are associated with coastal sedimentation has been of great value in the study of tsunamis prehistorically geological investigation of such sediments has resulted in the identification of a series of palaeotsunamis that appear to have taken place in different areas of the world in most cases however it has proved difficult to link former tsunamis to specific source mechanisms studies of modern tsunamis have also faced difficulties in the recognition of the specific source mechanisms for example offshore earthquakes may trigger submarine slides that combine to produce complex patterns of tsunami flooding at the coast

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

active thrusting as a possible seismogenic source in sicily southern italy some insights from integrated structural kinematic and seismological data abstract this paper proposes a new seismogenic interpretation of mainland and central southern sicily based on an integrated structural kinematic seismological approach through analysis of available structural and geophysical data the tectonic setting the major kinematic units and the crust geometry of the sicilian southward verging fold and thrust belt system are schematized in sections and in map form the depth contour lines of the outermost basal thrust plane which dates back to plio pleistocene times with some evidence of holocene activity are reconstructed this plane here named sicilian basal thrust sbt emerges along the southward convex sciacca gela catania front and reaches the base of the crust at a depth of about 30 km beneath northern sicily additionally an important regional upper crust splay with the same arched shape has been identified some kilometres northward in order to detect any possible indication of seismogenic activity linked to ongoing deformation of the sbt and its splay we analyzed the distribution and kinematics of the instrumental seismicity in the period between 1981 and 2006 particular attention was given to the background seismicity ml up to 4 6 located beneath the sedimentary cover at mt etna as it allows individuating a northward deepening seismogenic volume undergoing an average n s compression which corresponds well with the sbt geometry in section view a merged dataset of all the known major historical and instrumental events moment magnitude 4 5 that occurred above the sbt 0 to 30 km depth contour lines from 217 b c to 2006 was compiled and analyzed based on information from instrumental data and or on speculations on the shape and extent of the historical earthquake macroseismic fields two major ranges of hypocentral depths have been schematically identified within the merged dataset an upper crust range in average