proposed re dating of the european ice core chronology by seven years prior to the 7th century ad 1 progress in the study of past climate change requires integration of historical documentation tree ring data and ice core chemistry larsen et al 2008 re evaluate volcanic acid signals in the dye 3 grip and ngrip ice cores and identify large eruptions at 529 2 and 533 534 2 the latter claimed to cause the dry fog of 536 537 and environmental consequences to 550 this conflicts with previous suggestions of a two stage environmental event one in 536 the second c 540 understanding the full range of natural hazards requires critical evaluation of the happenings in the mid 6th century this paper will show that 4 spaced tree ring responses to extreme environmental conditions in the 6th century can be used to re locate 4 key ice acid dates moving the ice core chronology forward 7 years places two large volcanoes in 536 and 541 explaining the extended duration of the 536 550 effects and anchoring the ice chronology

revised calendar date for the taupo eruption derived by 14c wiggle matching using a new zealand kauri 14c calibration data set taupo volcano in central north island new zealand is the most frequently active and productive rhyolite volcano on earth its latest explosive activity about 1800 years ago generated the spectacu

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

probabilistic tsunami hazard in the mediterranean sea 1 estimating the occurrence probability of natural disasters is critical for setting construction standards and more generally prioritizing risk mitigation efforts tsunami hazard in the mediterranean region has traditionally been estimated by considering so called most credible scenarios of tsunami impact for limited geographical regions but little attention has been paid to the probability of any given scenario we present here the first probabilistic estimate of earthquake generated tsunami hazard for the entire mediterranean sea we estimate the annual probability of exceeding a given tsunami amplitude at any coastal location in the region by applying a monte carlo based technique earthquake activity rates are estimated from the observed seismicity and tsunami impact is derived from deterministic tsunami wave propagation scenarios the highest hazard is in the eastern mediterranean owing to earthquakes along the hellenic arc but most of the mediterranean coastline is prone to tsunami impact our method allows us to identify the main sources of tsunami hazard at any given location and to investigate the potential for issuing timely tsunami warnings we find that the probability of a tsunami wave exceeding 1 m somewhere in the mediterranean in the next 30 years is close to 100 this underlines the urgent need for a tsunami warning system in the region

tracking earthquake archaeological evidence in late minoan iiib 1300 1200 b c crete greece a proof of concept late minoan lm iiib 1300 1200 b c represents a crucial period in the history of bronze age crete heralding the transition to the iron age through a wave of site destruction and abandonment according to the traditional view earthquakes may have played a significant role in these events a new archaeoseismological approach is proposed to test this hypothesis and to attribute destruction and abandonment to earthquakes potential earthquake archaeological effects peaes are defined and documented at lm iiib sites synchronisms of peaes between sites are based on ceramic evidence the reliability of the peaes is furthermore assessed using empirical ground motion relationships defined for three types of earthquake mechanisms that can be considered to occur in the seismotectonic context of crete 1 normal faulting earthquakes located within the overriding aegean lithosphere 2 earthquakes located on the subduction interface or on splay faults merging with the interface at depth 3 earthquakes within the subducting african lithosphere in the case of lm iiib1 early malia and sissi northeastern crete this proof of concept is successfully applied and supports the hypothesis that seismic shaking is likely to be responsible for the peaes observed a 12 october 1856 a d type earthquake located within the subducting african plate is suggested as the most likely earthquake mechanism in other lm iiib archaeological contexts no convincing evidence for earthquake effects could be identified the hypothesis of a seismic storm causing the demise of minoan crete is not supported by our analysis of archaeological evidence

the ad 1300 1700 eruptive periods at tungurahua volcano ecuador revealed by historical narratives stratigraphy and radiocarbon dating tungurahua is a frequently active and hazardous volcano of the ecuadorian andes that has experienced pyroclastic flow forming eruption in 1773 1886 1916 18 and 2006 08 earlier eruptions in late pre hispanic and early colonial times have remained poorly known and are debated in the literature to reconstruct the eruptive chronology in that time interval we examine relevant historical narratives recently found in sevilla spain and rome italy and we combine stratigraphic field constraints with 22 new radiocarbon age determinations results show that pyroclastic flow forming eruptions and tephra falls took place repeatedly since similar to 700 c 14 yr bp when the tungurahua region was already populated radiocarbon ages averaging around 625 yr bp reveal a period of notable eruptive activity in the 14th century late integration cultural period the associated andesitic eruptions produced ash and scoria falls of regional extent and left scoria flow deposits on the western flanks of the edifice the fact that tungurahua was known by the puruhas indians as a volcano at the time of the spanish conquest in 1533 perhaps refers to these eruptions a group of ages ranging from 380 to 270 yr bp is attributed to younger periods of activity that also predates the 1773 event and calibration results yield eruption dates from late 15th to late 17th centuries i e inca and early colonial periods the historical narratives mention an early colonial eruption between the spanish conquest and the end of the 16th century followed by a distinct eruptive period in the 1640s the descriptions are vague but point to destructive eruptions likely accompanied by pyroclastic flows the dated tephras consist of andesitic scoria flow deposits and the contemporaneous fallout layers occur to the west these findings reveal that the eruption recurrence rate at tungurahua is at least one pyroclastic flow forming event per century since the 13th century and the occurrence of such eruptions in 2006 08 is thus fully consistent with the rate inferred for the past seven centuries in addition historical chronicles suggest that a notch opened in the crater margin during the 1640 decade as has occurred repeatedly in the past millennium at tungurahua such small volume collapse events represent a previously unrecognized source of hazards which deserve special attention for risk assessment purposes in the context of the currently ongoing eruption c 2008 elsevier b v all rights reserved

aminostratigraphy of quaternary marine and glaciomarine sediments qivitu peninsula baffin island a complex sequence of cyclical marine and glaciomarine lithofacies exposed along the coastal lowlands of the qivitu peninsula was deposited during the marine transgressions and regressions that affected this area during repeated glaciation of the region multivariate analysis of amino acid ratios measured on shell fragments of the pelecypods hiatella arctica and myatruncata in the lithostratigraphic units provides a basis for their chronocorrelation through the use of informal regional aminostratigraphic units termed aminozones all but the oldest aminozones correspond with particular lithostratigraphic units deposited during transgressive regressive periods when relative sea level was higher than present sea level discriminant analysis shows total amino acid fraction allo iso ratios from either species are the best overall criteria for assigning a shell sample to a particular aminozone but free fraction allo iso ratios are more useful in the younger zones the distribution of ratios in lithostratigraph

marine episodes in hudson strait and hudson bay canada during the wisconsin glaciation abstract twelve reworked shell fragments were recovered from five till samples collected on nottingham island in western hudson strait canada total hydrolysate amino acid ratios d alloisoleucine l isoleucine for each fragment range from 0 043 to 0 154 and are significantly higher than ratios for radiocarbon dated holocene shells which average 0 022 one shell fragment with an aile ile ratio of 0 065 yielded an ams radiocarbon age of 44 200 2300 yr b p aa 3254 absolute age estimates based on the amino acid ratios are constrained by reasonable limits on the estimated effective diagenetic temperature of the fossils on this basis the shell fragments are correlated with oxygen isotope substages 5e and 5a and stage 3 in the preferred hypothesis theses results independently support hypotheses calling for at least partial deglaciation and marine incursion in hudson strait and hudson bay at these times

new insights into the initiation and venting of the bronze age eruption of santorini greece from component analysis the late seventeenth century bc minoan eruption of santorini discharged 30 60 km3 of magma and caldera collapse deepened and widened the existing 22 ka caldera a study of juvenile cognate and accidental components in the eruption products provides new constraints on vent development during the five eruptive phases and on the processes that initiated the eruption the eruption began with subplinian phase 0 and plinian phase 1 phases from a vent on a ne sw fault line that bisects the volcanic field during phase 1 the magma fragmentation level dropped from the surface to the level of subvolcanic basement and magmatic intrusions the fragmentation level shallowed again and the vent migrated northwards during phase 2 into the flooded 22 ka caldera the eruption then became strongly phreatomagmatic and discharged low temperature ignimbrite containing abundant fragments of post 22 ka pre minoan intracaldera lavas phase 3 phase 4 discharged hot fluidized pyroclastic flows from subaerial vents and constructed three main ignimbrite fans northwestern eastern and southern around the volcano the first phase 4 flows were discharged from a vent or vents in the northern half of the volcanic field and laid down lithic block rich ignimbrite and lag breccias across much of the nw fan about a tenth of the lithic debris in these flows was subvolcanic basement new subaerial vents then opened up probably across much of the volcanic field and finer grained ignimbrite was discharged to form the e and s fans if major caldera collapse took place during the eruption it probably occurred during phase 4 three juvenile components were discharged during the eruption a volumetrically dominant rhyodacitic pumice and two andesitic components microphenocryst rich andesitic pumices and quenched andesitic enclaves the microphenocryst rich pumices form a textural mineralogical chemical and thermal continuum with co erupted hornblende diorite nodules and together they are interpreted as the contents of a small variably crystallized intrusion that was fragmented and discharged during the eruption mostly during phases 0 and 1 the microphenocryst rich pumices hornblende diorite andesitic enclaves and fragments of pre minoan intracaldera andesitic lava together form a chemically distinct suite of ba rich zr poor andesites that is unique in the products of santorini since 530 ka once the minoan magma reservoir was primed for eruption by recharge generated pressurization the rhyodacite moved upwards by exploiting the plane of weakness offered by the pre existing andesite diorite intrusion dragging some of the crystal rich contents of the intrusion with it

pumice deposits of the santorini lower pumice 2 eruption on anafi island greece indications for a plinian event of exceptional magnitude abstract isolated patches of santorini pumice deposits are analysed from the non volcanic island of anafi at a distance of 31 38 km east from the centre of the santorini caldera the deposits are plinian fall profiles with a primary thickness at this distance of 1 2 1 5 m and mp maximum pumice and ml maximum lithic diameters of 5 and 4 cm respectively the characteristic profile sequence of the analysed anafi deposits corresponds perfectly with the plinian sequence of the lower pumice 2 lp2 profiles on thera the main island of the santorini group with the sub divisions into lp2 a2 1 lp2 a2 2 and lp2 a3 pumice glass chemistry phenocryst assemblage and the significant content of grey cauliform scoriae make the compositional correlation with the plinian lp2 eruption of santorini unambiguous with the new identification of lp2 deposits on anafi together with an 4 5 times greater thickness in the main axis of dispersal of the proximal plinian lp2 deposits compared to the minoan fallout on thera the plinian opening phase of the 172 ka lp2 eruption lp2 a is regarded by far as the most voluminous of all plinian eruptive phases on santorini

reply to a s dyke s discussion abstract in our opinion the amino acid data are consistent with the till nonglacial stratigraphy we reject dyke s proposal that the plotting of data in 0 04 increments is appropriate as an unwarranted interpretation that errors are cumulative we also see no grounds for accepting his alternative interpretation that the groups of amino acid ratios reflect various transport read temperature histories of a single population of bell sea shells it is our opinion that the relative sequence of marine incursions in hudson bay is reliable and we repeat that the evidence favors one or more deglacial events we stress that the ages of the units between the tyrrell sea and bell sea end membrers are interpolated and that the chronology of events is currently based on the assumption that the bell sea represents marine incursion at the onset of marine isotope stage 5 dyke has raised a number of points which have concerned us since we started our joint research on the aminostratigraphy of the hudson bay lowlands the answer to many questions will come not from the amino acid results per se but from detailed litho and biostratigraphic logging of the thousands of kilometers exposed along the large rivers that drain into james bay and southwestern hudson bay this work is presently going on let us say in conclusion that analysis of a further 63 shells and shell fragments resulted in a virtually identical frequency distribution to that discussed in our paper we are currently evaluating the stratigraphic integrity of these results field expeditions by the geological survey of canada in 1982 and 1983 into the hudson bay lowlands were specifically designed to log new sections and make additional shell collections we hope to report on these new data in due course

fluid geochemistry contribution to the interpretation of the 2011 2012 unrest of santorini greece in the frame of the dynamics of the aegean volcanic arc

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

multi proxy dating of holocene maar lakes and pleistocene dry maar sediments in the eifel germany abstract during the last twelve years the elsa project eifel laminated sediment archive at mainz university has drilled a total of about 52 cores from 27 maar lakes and filled in maar basins in the eifel germany dating has been completed for the holocene cores using 6 different methods 210pb and 137cs activities palynostratigraphy event markers varve counting 14c in general the different methods consistently complement one another within error margins event correlation was used for relating typical lithological changes with historically known events such as the two major holocene flood events at 1342 ad and ca 800 bc dating of mis2 mis3 core sections is based on greyscale tuning radiocarbon and osl dating magnetostratigraphy and tephrochronology the lithological changes in the sediment cores demonstrate a sequence of events similar to the north atlantic rapid climate variability of the last glacial cycle the warmest of the mis3 interstadials was gi14 when a forest with abundant spruce covered the eifel area from 55 to 48 ka bp i e during a time when also other climate archives in europe suggested very warm conditions the forest of this early stage 3 warm phase developed subsequently into a steppe with scattered birch and pine and finally into a glacial desert at around 25 ka bp evidence for mono lake and laschamp geomagnetic excursions is found in two long cores several large eruptions during middle and late pleistocene ulmener maar 11 000 varve years bp laacher see 12 900 varve years bp mosenberg volcanoes meerfelder maar 41 45 cal ka bp dumpel maar 116 ka bp glees maar 151 ka bp produced distinct ash layers crucial for inter core and inter site correlations the oldest investigated maar of the eifel is 40ar 39ar dated to the time older than 520 ka bp

reconstructing the tephra dispersal pattern from the bronze age eruption of santorini using an advection diffusion model the advection diffusion model tephra2 has been used in conjunction with the downhill simplex method dsm and one at a time oat inversion methods to reconstruct the eruption conditions and seasonality consistent with the deposit patterns from the bronze age minoan eruption of santorini we investigated three datasets representing different depositional environments proximal terrestrial distal terrestrial and deep sea core in order to determine source conditions such as plume height erupted mass and grain size and recreate the tephra fall deposit from the plinian co ignimbrite and combined eruptive phases the results of the dsm and oat method agreed adequately well with each other for erupted mass plume height and grain size distribution both approaches were able to successfully recreate the plinian deposit but estimating conditions that created the co ignimbrite and deep sea core dataset were less successful the reduced agreement is the result of the low quantity 6 to 28 deposit points and quality inconsistent deposit depths at localities adjacent to each other of the datasets and the different dynamics between co ignimbrite and plinian columns with the former not well represented in the model different sampling methods between archaeological and volcanological disciplines and post depositional processes which have acted on the tephra deposits since the bronze age can explain the discrepancy between these computed and observed deposits the seasonality of the minoan eruption was investigated by using seasonal wind profiles for winter spring summer and autumn we find that the bronze age eruption of santorini is likely to have during the spring and summer months with a main dispersal axis aligned east crete would have received very little ash fall and the eruption would not have caused much disruption to the life of the inhabitants of the island

evolution of santorini volcano dominated by episodic and rapid fluxes of melt from depth santorini volcano in greece was thought to be continually charged by small injections of magma measurements of surface deformation show that magma equivalent to 10 50 of that emitted in previous small eruptions has been injected beneath santorini since january 2011 implying that the volcano is instead charged by rapid episodic fluxes of melt

radiocarbon simulation fails to support the temporal synchroneity requirement of the younger dryas impact hypothesis fine scale temporal processes such as the synchronous deposition of organic materials can be challenging to identify using 14 c datasets while some events such as volcanic eruptions leave clear evidence for synchronous deposition synchroneity is more difficult to establish for other types of events this has been a source of controversy regarding 14 c dates associated with a hypothesized extraterrestrial impact at the younger dryas boundary ydb to address this controversy we first aggregate 14 c measurements from northern hemisphere ydb sites we also aggregate 14 c measurements associated with a known synchronous event the laacher see volcanic eruption we then use a monte carlo simulation to evaluate the magnitude of variability expected in a 14 c dataset associated with a synchronous event the simulation accounts for measurement error calibration uncertainty old wood effects and laboratory measurement biases the laacher see 14 c dataset is consistent with expectations of synchroneity generated by the simulation however the ydb 14 c dataset is inconsistent with the simulated expectations for synchroneity these results suggest that a central requirement of the younger dryas impact hypothesis synchronous global deposition of a ydb layer is extremely unlikely calling into question the younger dryas impact hypothesis more generally

santorini eruption radiocarbon dated to 1627 1600 b c precise and direct dating of the minoan eruption of santorini thera in greece a global bronze age time marker has been made possible by the unique find of an olive tree buried alive in life position by the tephra pumice and ashes on santorini we applied so called radiocarbon wiggle matching to a carbon 14 sequence of tree ring segments to constrain the eruption date to the range 1627 1600 b c with 95 4 probability our result is in the range of previous less precise and less direct results of several scientific dating methods but it is a century earlier than the date derived from traditional egyptian chronologies

constraining the late pleistocene history of the laurentide ice sheet by dating the missinaibi formation hudson bay lowlands canada abstract well dated paleorecords from periods prior to the last glacial maximum lgm are important for validating models of ice sheet build up and growth however owing to glacial erosion most late pleistocene records lie outside of the previously glaciated region which limits their ability to inform about the dynamics of paleo ice sheets here we evaluate new and previously published chronology data from the missinaibi formation a pleistocene aged deposit in the hudson bay lowlands hbl canada located near the geographic center of the laurentide ice sheet lis available radiocarbon ams 44 conventional 36 amino acid n 13 uranium thorium u th n 14 thermoluminescence tl n 15 and optically stimulated luminescence osl n 5 data suggest that an ice free hbl may have been possible during parts of marine isotope stage 7 mis 7 ca 243 000 to ca 190 000 yr bp mis 5 ca 130 000 to ca 71 000 yr bp and mis 3 ca 29 000 to ca 57 000 while mis 7 and mis 5 are well documented interglacial periods the development of peat forest bed and fluvial deposits dating to mis 3 n 20 radiocarbon dates 4 tl dates 3 osl dates suggests that the lis retreated and remained beyond or somewhere within the boundaries of the hbl during this interstadial ice sheet models approximate the margin of the lis to southern ontario during this time which is 700 km south of the hbl therefore if correct our data help constrain a significantly different configuration and dynamicity for the lis than previously modelled we can find no chronological basis to discount the mis 3 age assignments however since most data originate from radiocarbon dates lying close to the reliable limit of this geochronometer future work on dating the missinaibi formation using other geochronological methods e g u th osl is necessary in order to confirm the age estimates and strengthen the boundaries of the lis during this period

late wisconsinan glaciation of southern eureka sound evidence for extensive innuitian ice in the canadian high arctic during the last glacial maximum abstract southern eureka sound was originally proposed as the centre of an innuitian ice sheet in the canadian high arctic at the last glacial maximum lgm based largely on the pattern of holocene emergence this paper focuses on the glacial geological evidence for such an ice sheet in the region granite dispersal trains and ice moulded bedrock record regional westward flow of warm based ice into eureka sound from se ellesmere island regional ice was coalescent with local ice domes on inter fiord peninsulas marine limit in the form of raised deltas beaches and washing limits formed during deglaciation of the regional ice throughout southern eureka sound marine limit dates 9 2 ka bp indicating that ice commenced retreat during the early holocene ice divides were located along the highlands of central ellesmere and axel heiberg islands from which ice inundated eureka sound flowing north and south along the channel regional radiocarbon dates on marine limit show that deglaciation occurred in two steps initial break up and radial retreat of ice from eureka sound to the inner fiords was rapid and preceded stabilisation along adjacent coastlines and at fiord heads two step deglaciation is also reflected in differences in glacial geomorphology between the inner and outer parts of many fiords a prominent belt of fiord head glaciogenic landforms long proposed to mark the last glacial limit is re interpreted to record initial stabilisation of ice margins due predominantly to bathymetric control

historical bathymetric charts and the evolution of santorini submarine volcano greece historical bathymetric charts are a potential resource for better understanding the dynamics of the seafloor and the role of active processes such as submarine volcanism the british admiralty for example have been involved in lead line measurements of seafloor depth since the early 1790s here we report on an analysis of historical charts in the region of santorini volcano greece repeat lead line surveys in 1848 late 1866 and 1925 1928 as well as multibeam swath bathymetry surveys in 2001 and 2006 have been used to document changes in seafloor depth these data reveal that the flanks of the kameni islands a dacitic dome complex in the caldera center have shallowed by up to 175 m and deepened by up to 80 m since 1848 the largest shallowing occurred between the late 1866 and 1925 1928 surveys and the largest deepening occurred during the 1925 1928 and 2001 and 2006 surveys the shallowing is attributed to the emplacement of lavas during effusive eruptions in both 1866 1870 and 1925 1928 at rates of up to 0 18 and 0 05 km3 a 1 respectively the deepening is attributed to a load induced viscoelastic stress relaxation following the 1866 1870 and 1925 1928 lava eruptions the elastic thickness and viscosity that best fits the observed deepening are 1 0 km and 1016 pa s respectively this parameter pair which is consistent with the predictions of a shallow magma chamber thermal model explains both the amplitude and wavelength of the historical bathymetric data and the present day rate of subsidence inferred from insar analysis

the initiation and development of a caldera forming plinian eruption 172 ka lower pumice 2 eruption santorini greece the rhyodacitic 172 ka lower pumice 2 lp2 eruption terminated the first magmatic cycle at santorini greece producing a proximal 50 m thick succession of pyroclastic fall deposits diffusely stratified to massive ignimbrites and multiple lithic breccias the eruption commenced with the development of a short lived precursory eruption column depositing a 15 cm blanket of 1 2 cm sized pumice fragments at near vent localities lp2 a1 the precursor deposits are conformably overlain by a 30 m thick sequence of reversely graded ungraded pumice fall deposits that reflect opening and widening of a point source vent increasing mass discharge rates up to 108 kg s 1 and the development of a 36 km high plinian eruption column lp2 a2 a3 the progressive increase in maximum vesicle number density nvf in rhyodacitic pumice from 3 2 109 cm 3 in the basal fall unit of lp2 a2 1 to 9 2 109 cm 3 in lp2 a3 translates to an increase in magma decompression rate from 18 to 29 mpa s 1 over the course of the initial plinian phase this is interpreted to be a consequence of progressive vent widening and a deepening of the fragmentation surface such interpretations are supported by the increase in lithic clast abundance vertically through lp2 a and the occurrence of basement derived deep lithic components in lp2 a3 the increasing lithic clast content and the inability to effectively entrain air into the eruption column due to vent widening resulted in column collapse and the development of pyroclastic density currents pdcs lp2 b a major vent excavation event or the opening of new vents possibly associated with incipient caldera collapse facilitated the ingress of water into the magmatic system the development of widespread pdcs and the deposition of a 20m thick massive phreatomagmatic tuff lp2 c the eruption cumulated in catastrophic caldera collapse the enlargement of a pre existing flooded caldera and the discharge of lithic rich pdcs depositing proximal 9 m thick lithic lag breccias lp2 d

dendrochemical analysis of a tree ring growth anomaly associated with the late bronze age eruption of thera the most marked tree ring growth anomaly in the aegean dendrochronological record over the last 9000 years occurs in the mid 17th century bc and has been speculatively correlated with the impact of the late bronze age eruption of thera santorini if such a connection could be proved it would be of major interdisciplinary significance it would open up the possibility of a precise date for a key archaeological geological and environmental marker horizon and offer a direct tie between tree ring and ice core records some 3600 years ago a volcanic explanation for the anomaly is highly plausible yet in the absence of a scientifically proven causal connection the value of the proposed correlation is limited in order to test the hypothesis dendrochemical analysis via synchrotron radiation scanning x ray fluorescence microscopy sxfm inductively coupled plasma atomic emission spectroscopy icp aes and inductively coupled plasma mass spectroscopy icp ms was carried out on growth ring series from four trees displaying the anomaly increases of sulfur calcium and rare earth elements following the onset of altered growth plus concentration spikes of zinc and hafnium in the first affected growth ring provide promising new evidence in support of a volcanic causal factor although a volcanic association is implied the new data are not sufficient to prove a link to the exact eruption source

field based validation of a diagenetic effect on g ruber mg ca paleothermometry core top results from the aegean sea eastern mediterranean recent work across the mediterranean sea has illustrated the salinity and overgrowth effects on planktonic foraminiferal mg ca which potentially confound the use of this as a temperature proxy for paleoceanographic reconstructions to test and verify these effects we present new aegean sea results which reveal mg ca values that were unreasonably high to be explained by temperature or salinity variations alone confirming that foraminiferal mg ca is affected by diagenesis we have specifically targeted globigerinoides ruber w sensu stricto from a series of modern core tops spanning a strong sea surface salinity gradient and a minor sea surface temperature range along a north south aegean sea transect scanning electron microscopy analyses show that g ruber specimens were covered by microscale euhedral crystallites of inorganic precipitates this secondary calcite phase seems to be responsible for the anomalously high mg ca ratios and likely formed near the sediment water interface from caco3 supersaturated interstitial seawater we also have clear evidence of diagenetic alteration in a north south direction along the aegean sea possibly depending on salinity and calcite saturation state gradients these observations illustrate the necessity of alternative techniques e g flow through time resolved analysis or laser ablation inductively coupled plasma mass spectrometry to potentially overcome these diagenetic issues and develop a more reliable and sensitive temperature proxy in similar subtropical settings characterized by high salinity excessive evaporation and restricted circulation

calendar dated glacier variations in the western european alps during the neoglacial the mer de glace record mont blanc massif holocene glacier records from the western european alps are still sparse although a number of sites are well suited to constraining pre and early little ice age lia glacier advances the present study provides the first dendrochronologically based and calendar dated neoglacial glacier chronology for the mont blanc massif french alps it is based on the analysis of over 240 glacially buried pinus cembra subfossil logs and wood remains found either embedded in till or as detrital material in the mer de glace right lateral moraine only a few of the samples were found to be formally in situ but we show that some logs were virtually in situ not rooted but showing little or no evidence of reworking and could be used to accurately reconstruct past glacier margin behavior in space and time uncertainties regarding the other samples may relate to original growth location and or to outer wood decay the resulting dates followed by a were therefore considered maximum limiting ages for glacier advances the main burial events interpreted as glacier advances occurred between ca 1655 and 1544 bc between ca 1230 and 1105 bc between ca 1013 and 962 937 bc at ca 802 777 bc after 608 bc between 312 and 337 ad between ca 485 ad and 606 ad between 1120 and 1178 ad between ca 1248 and 1278 1296 ad and after 1352 ad these advances predate the late lia maxima known from historical sources the magnitude of the advances gradually increased to culminate in three near neoglacial maxima during the 7th 12th and 13th centuries ad followed by a first lia neoglacial maximum in the second half of the 14th century ad the pattern of neoglacial events described here is coherent with central and eastern alpine glacier chronologies this indicates marked synchronicity of late holocene glacier variability and forcing at a regional scale although occasional differences could be detected between western and eastern records the mer de glace record also confirms the link between the timing of sediment erosion in a high elevation glaciated alpine catchment and subsequent deposition in the sub alpine lake bourget

multiple deglaciations of the hudson bay lowlands canada since deposition of the missinaibi last integlacial formation abstract the stratigraphic record in the james and hudson bay lowlands indicates that the sequence of glacial events at the geographical center of the 12 6 10 6 km 2 laurentide ice sheet may have been more complex than hitherto imagined isoleucine epimerization ratios of in situ and transported shells recovered from till and associated marine and fluvial sediments cluster into at least 4 discrete groups two alternative explanations of the data are offered of which we strongly favor the first hypothesis 1 setting the age of the last interglacial marine incursion the bell sea at 130 000 yr b p results in a long term average diagenetic temperature for the lowlands of 0 6 c using this temperature enables us to predict the age of shells intermediate in age between the last interglaciation and the incursion of the tyrrell sea 8000 yr ago between these two interglacial marine inundations hudson bay is predicted to have been free of ice along its southern shore about 35 000 75 000 and 105 000 yr ago based on amino acid ratios from shells occurring as erratics in several superimposed tills and fluvial sediments these results suggest 1 that traditional concepts of ice sheet build up and decay must be reexamined 2 that high sea levels may have occurred during the wisconsin glaciation and 3 that a critical reappraisal is required of the open ocean 18 o record as a simple indicator of global ice volume an alternative hypothesis 2 is also examined it is based on the assumption that the 35 000 yr old deposits calculated on the basis of hypothesis 1 date from the last interglaciation this in effect indicates that the missinaibi formation commonly accepted as sediments of the last interglaciation are about 500 000 yr old and that the effective diagenetic temperature in the lowlands during approximately the last 130 000 yr has been close to 6 c we argue for rejection of this alternative hypothesis

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

glacial terminations in the oxygen isotope record of deep sea cores hypothesis of massive antarctic ice shelf destruction abstract glacial terminations i and ii in the deep sea core foraminiferal oxygen isotope ratios though not similar in form are each characterized by a short interval of about 3 ka during which a large negative change occurred in the ratios after correcting for temperature effects we estimate that each change was equivalent to a glacial disintegration capable of causing a 50 60 m eustatic sea level rise in the termination i interval 16 13 ka b p the estimated equivalent sea level rise is much larger than that suggested by the best evidence of deglacial ice loss from the laurentide ice sheet which is thought to dominate pleistocene glacial ice volume changes moreover in termination ii about 125 ka b p the estimated equivalent sea level rise is much larger than that inferred from the stratigraphy of coral reefs and beaches on new guinea and other locations which suggests quite high sea levels for 10 ka prior to this termination to reconcile these severely conflicting lines of evidence we propose that the rapid negative isotope ratio changes were largely caused by the disintegration of massive floating antarctic ice shelves which masqueraded as land ice in the oceanic isotope ratios but which contributed no sea level change we propose that such shelves were formed when oceanic circulation changes in the north atlantic under glacial conditions greatly reduced the formation of relatively warmer north atlantic deep water and its injection into circumpolar antarctic regions and that the shelves disintegrated rapidly with the resumption of large scale formation of this deep water and its input into the antarctic we find that high sea levels in the 125 135 ka b p interval prior to termination ii which imply very little northern ice then are well supported by dated coral reef stratigraphy although these ages were not accepted by the climap study of the last interglacial ocean minimal northern ice volumes at that time imply that strong milankovitch summer insolation is not always required for northern deglaciation a promising additional deglacial mechanism is the prolonged viscous depression of the crust beneath the laurentide ice sheet combined with atmospheric oceanic circulation factors

possible tsunami inundation identified amongst 4 5th century bce archaeological deposits at tel ashkelon israel abstract the eroding coastal sections of ashkelon israel contain exposed sequences of natural and anthropogenic sedimentological deposits some of unknown origin ashkelon an important and long occupied ancient coastal city is directly referred to within written records of past tsunami events yet field studies and archaeological descriptions have not yet corroborated these claims this is not unusual nor unexpected given the amount of anthropogenic and natural disturbance that can erase the sedimentary remains as well as the relatively recent advancements in identifying such deposits a sequence of sediments at the base of an eroding coastal archaeological section shows clear waterborne transport characteristics and was previously interpreted as alluvial however no alluvial sources could be associated to the deposit in this study the sedimentological characteristics of this section were described and analyzed in greater detail to determine their nearest similarity to possible transport mechanism such as storms rivers and tsunamis the deposits contain fining upward sequences rip up clasts imbricated inclusions fine mud layers microfauna foraminifera and broken diagnostic pottery from the 4 5th c bc reconstructions of the coastline at the time of the event place the sampled profile at least 100 m inland from the shoreline at an elevation 2 0 to 2 4 m above sea level river channel features were not identified in the section for this area modern observations of major storms show inundations of

mid holocene tectonic geomorphology of northern crete deduced from a coastal sedimentary archive near rethymnon and a late bronze age santorini tsunamite candidate abstract the late bronze age lba tsunami and the a d 365 tsunami are supposed to have affected the northern coasts of crete however near coast sedimentary archives have been rarely investigated in this area and sedimentary archives including palaeotsunami fingerprints are still unknown the main objective of our research was to search for appropriate tsunami sediment traps in order to gain detailed insights into the holocene palaeotsunami history of northern crete we found an excellent fine sediment archive near pirgos located to the west of rethymnon based on a multi electrode geoelectrical survey and an 11 m deep sediment core we analysed the event geochronostratigraphical record by means of sedimentological geochemical geochronological geomorphological and microfossil investigations the pirgos record revealed a thick unit of homogeneous mud of a lagoonal environment starting 6000 years ago the lagoon was affected by five high energy events leaving layers of allochthonous sand microfossil analyses of these layers revealed a mixed foraminiferal assemblage including species from brackish habitats but also displaced and transported species from open marine and deep water environments considering sedimentary characteristics the local wave climate of the cretan sea and the overall geomorphological setting we interpret these layers as related to extreme wave events ewe based on a local radiocarbon age depth model we identified one ewe layer as a reliable candidate for the lba santorini tsunami another ewe layer is most probably associated with the a d 365 tsunami this ewe ended abruptly the lagoonal conditions at pirgos because of to the 1 64 m coseismic uplift at the site the pirgos lagoon existed between the first half of the 6th mill b c and at least the end of the 2nd mill b c we found that the area around pirgos has continuously subsided over 3000 or so years reflecting constant tectonogeomorphological conditions dominated by the nearby subduction zone between the aegean and african plates

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

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

volcanic ash fall events identified using principal component analysis of a high resolution speleothem trace element dataset large multivariate trace element datasets produced by la icp ms speleothem analysis can pose difficulties for analysis and interpretation processes acting on various timescales and magnitudes affect trace element concentrations and deconvolving the most important controls is often complex here principal component analysis pca is applied to identify the modes and timings of variation which best explain the overall variability in an exceptionally high resolution 10 m vertical resolution multivariate trace element record produced by la icp ms from a modern 1979 2001 belizean stalagmite with excellent age control principal component 1 pc1 in this dataset is defined by a weak correlation between multiple elements and may reflect non carbonate material incorporated within the speleothem elevated pc1 scores in atm 7 occur following regional volcanic eruptions with ash clouds extending over the cave site as demonstrated using nasa remote sensing data from the total ozone mapping spectrometer and hysplit trajectory modelling spikes in pc1 occur at the beginning of the wet season and this may reflect a seasonal flushing event that transports volcanogenic material through the karst and incorporates it within the speleothem our results suggest that pca can simplify exploration of large laser ablation datasets and that pca is a valuable tool for identifying the dominant controls on stalagmite trace element chemistry future studies should evaluate how transferable this technique is to other sites with different environmental conditions where volcanic ashfall has occurred this research potentially adds tephrochronology to the stalagmite dating toolkit or conversely opens the door to using stalagmites to identify previously unknown or uncertainly dated eruptions

recognition of the minoan tephra in the acigol basin western turkey implications for inter archive correlations and fine ash dispersal here we report the recognition of the minoan tephra layer in the acigol basin western turkey which represents the most eastward occurrence of this tephra on land and the first in continental deposits out of lacustrine sediments in mainland turkey the correlation is supported by glass and mineral geochemistry which includes solution and laser ablation icp ms data for trace and rare earth elements thickness and grain size data allow the extension of already described occurrences to an area of about 359 000 km 2 from the eastern mediterranean to black sea throughout central western turkey coupling dispersal area and grain size data suggests the joint influence of high and low atmosphere dynamics in dispersal of fine ash during volcanic eruptions the thickness and lateral continuity of the minoan tephra in the acigol basin testifies to the widespread impact on the late bronze age environment of mainland turkey of this important ash deposit copyright 2013 john wiley sons ltd

volcanism and the greenland ice cores the tephra record abstract in recent years increased awareness of the considerable potential offered by tephrochronology in palaeoclimatic studies has fuelled a renewed interest in the tephra record preserved within the greenland ice cores this renewal has occurred in tandem with the development of continuous flow analysis techniques which provide high resolution volcanic aerosol records these chemical records are of considerable value for identifying tephra horizons composed of glass shards and also provide the basis for a new high precision ice core timescale thus allowing ages to be assigned to volcanic events tephra horizons of glass shards in the ice cores play a critical role for 1 testing and building chronological frameworks for the ice cores and other sequences 2 synchronising disparate palaeoclimatic sequences and testing phase relationships 3 atmospheric pathway reconstruction and 4 verifying the source of volcanic aerosol peaks here we review the results of over 25 years of research into tephra horizons in the grip gisp2 and ngrip cores we provide high precision ages for horizons based on recently developed timescales and draw together geochemical characterisations of the products of 45 volcanic events deposited on the greenland ice sheet and identified in the cores there is a clear disparity between the number of volcanic aerosol peaks and the number of tephra horizons of glass shards identified thus far however this synthesis highlights the critical role of the greenland ice cores firstly in the reconstruction of the history of icelandic volcanic eruptions and secondly the considerable value of some tephra horizons in facilitating the correlation of these key climatic archives to north atlantic marine sequences other noteworthy issues include the potential of these cores to preserve tephra horizons from more distal volcanic sources such as north america to resolve the debate surrounding the thera eruption and the observation that some tephra horizons are preserved within the ice without coeval volcanic aerosol signals

human environment interaction in the hinterland of ephesos as deduced from an in depth study of lake belevi west anatolia abstract lacustrine sediments are important archives for high resolution palaeoenvironmental reconstructions of the holocene despite the density of ancient cities and settlements along the western coast of turkey the archives from coastal lakes in this area have until now not been recognized to their fullest potential and are therefore only poorly studied the exceptional geo bio archive of lake belevi is located close to the ancient city of ephesos in western turkey two sediment cores have been analysed using geochemical sedimentological microfaunal palynological and archaeoparasitological methods the in depth study of these holocene deposits is supported by a robust age depth model that used 33 radiocarbon dates and tephrochronology the results reveal the existence of a freshwater lake in the early holocene which turned brackish when the rising sea level connected it with the sea the delta evolution of the kucuk menderes led to the re establishment of a freshwater lake the natural vegetation was represented by open oak woodlands there are hints for first agricultural activities in the environs of belevi as early as 8000 cal yr bp intensive cultivation of olea is proven since 3000 cal yr bp starting during the 3rd millennium bp the human impact with enhanced deforestation activities and correlative high sedimentation rates is attested for sites such as belevi ephesos elaia pergamon and miletos for the first time tephra from the eruption of minoan santorini has been identified in the environs of ephesos this ash covered the vegetation by a thick layer wherefore low growing plants were strongly affected the comparison between the results from the quasi natural area of lake belevi and the area around the city of ephesos gives insights into the development and use of the landscapes the environmental changes as well as the duration and intensity of the human impact

complex variations during a caldera forming plinian eruption including precursor deposits thick pumice fallout co ignimbrite breccias and climactic lag breccias the 184 ka lower pumice 1 eruption sequence santorini greece the 184 ka lower pumice 1 eruption sequence records a complex history of eruption behaviours denoted by two significant eruptive phases 1 a minor precursor lp1 pc and 2 a major plinian phase lp1 a b c the precursor phase produced 13 small volume pyroclastic fallout surge and flow deposits which record the transition from a dominantly magmatic to a phreatomagmatic eruptive style and exhibit a normal dacite to andesitic dacite to reverse andesitic dacite to dacite compositional zonation of juvenile pyroclasts in the stratigraphy incipient bioturbation and variability in unit thickness and lithology reflect multiple time breaks and highlight the episodic nature of volcanism prior to the main plinian eruption phase the plinian magmatic eruption phase is defined by three major stratigraphic divisions including a basal pumice fallout deposit lp1 a an overlying valley confined ignimbrite lp1 b and a compositionally zoned rhyodacite to basaltic andesite lithic rich lag breccia lp1 c which caps the sequence this sequence records the initial development of a buoyant convective eruption column and the transition to eruption column and catastrophic late stage caldera collapse events similarities in pyroclast properties i e chemistry density between the plinian fallout lp1 a and pyroclastic flow lp1 b deposits indicate that changes in magma properties exerted no influence on the dynamics and temporal evolution of the lp1 eruption conversely lithic breccias at the base of the lp1 b ignimbrite suggest that the transition from a buoyant convective column to column collapse was facilitated by mechanical erosion of the conduit system and or the initiation of caldera collapse leading to vent widening an increase in magma discharge rate and the increased incorporation of lithics into the eruption column causing mass overload lithic rich lag breccia deposits lp1 c which cap the eruption sequence record incremental high energy caldera collapse events whereby downfaulting occurred in discrete jumps resulting in variable magma discharge rates and the development of a fissure vent system

real world based immersive virtual reality for research teaching and communication in volcanology direct outcrop observation and field data collection are key techniques in research teaching and outreach activities in volcanic areas however very often outcrops are of difficult or impossible access such as in areas with active volcanoes or steep cliffs classical remote sensing surveys by satellites or airplanes are expensive rarely reach sufficient resolution to allow high quality 3d visualisation of volcanic features and do not facilitate mapping of vertical cliffs we describe a novel approach that uses immersive virtual reality vr based on real world 3d digital outcrop models doms from images surveyed by unoccupied aerial system uas 3d doms are built up using the structure from motion sfm photogrammetry technique and a vr scene is created using game engine technologies immersive real time exploration of the environment is possible through a head mounted display e g oculus rift tools embedded in the vr environment allow the user to map polygons lines and point features tools also allow to measure orientation dip inclination azimuth area and thickness and even take virtual photographs using three examples of volcanic areas with different geological features we demonstrate the potential of our approach to allow users to be able to virtually map and measure remotely and to collect data for research and teaching our approach is of paramount importance also for outreach as it allows non specialist audiences e g common citizens to experience and appreciate highly complex volcanic features through customised hands on immersive vr tools

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

holocene tephras highlight complexity of volcanic signals in greenland ice cores 1 acidity peaks in greenland ice cores have been used as critical reference horizons for synchronizing ice core records aiding the construction of a single greenland ice core chronology gicc05 for the holocene guided by gicc05 we examined sub sections of three greenland cores in the search for tephra from specific eruptions that might facilitate the linkage of ice core records the dating of prehistoric tephras and the understanding of the eruptions here we report the identification of 14 horizons with tephra particles including 11 that have not previously been reported from the north atlantic region and that have the potential to be valuable isochrons the positions of tephras whose major element data are consistent with ash from the katmai ad 1912 and oraefajokull ad 1362 eruptions confirm the annually resolved ice core chronology for the last 700 years we provide a more refined date for the so called ad860b tephra a widespread isochron found across nw europe and present new evidence relating to the 17th century bc thera aniakchak debate that shows n american eruptions likely contributed to the acid signals at this time our results emphasize the variable spatial and temporal distributions of volcanic products in greenland ice that call for a more cautious approach in the attribution of acid signals to specific eruptive events

a multi proxy shallow marine record for mid to late holocene climate variability thera eruptions and cultural change in the eastern mediterranean abstract the river nile catchment is considered the major source of nutrient rich freshwater and sediment draining into the eastern mediterranean sea thus exceptional high resolution record from the nile littoral cell likely traces changes in the nile outflows related to climatic changes driven by the monsoonal system this study used multi proxy analyses combining sedimentological geochemical and organic stable isotope data along with foraminiferal data in a southeastern levantine inner shelf sedimentary sequence to understand mid to late holocene northeast african climate variability the palynological record is used to reconstruct local scale changes in the regional vegetation related to the mediterranean climate system the analyzed records reveal multi decadal to centennial pacing of paleoceanographic and paleoclimatic changes with most prominent events recorded at 4 28 3 6 and at 2 9 kyr bp these transitional periods characterized by simultaneous high 15n values and low total organic carbon toc suggest drier climatic conditions decrease in nile discharge leading to lower nutrient supply a stable and arid climate during mid late holocene 4 5 3 6 cal kyr bp associated with a weaker monsoon system as well as with a weaker mediterranean climate system is indicated based on high and constant sedimentation rates 400 cm kyr 1 along with relatively stable values and only occasional weak fluctuations documented in all of the proxies this climatic pattern is punctuated by a peak in maximum aridity at 4 28 kyr bp evidenced by low toc value and low arboreal pollen ap and artemisia chenopodiaceae a c pollen ratios and the sharp decline in the abundance of benthic foraminifera cribroelphidium poeyanum and valvulineria bradyana this change corresponds with the well studied 4 2 kyr bp drought event in the middle east mesopotamia and south asia during the late holocene 3 6 2 8 cal kyr bp the climate became unstable characterized by shifts between relatively wetter and drier conditions as evident in considerable fluctuations in all proxies maximum positive excursions of toc values c n ratio along with high dominance of opportunistic foraminiferal species e g ammonia tepida indicate northeast african wetter conditions and increased nile discharge at 3 5 3 3 3 2 and 3 0 kyr bp the distinct and abrupt transition from a stable to an unstable climate regime around 3 6 kyr bp may have been influenced by the thera volcanic eruption thus the sedimentary record investigated in this study may provide evidence for the impacts of this well known volcanic eruption not just on the climate regime in the levant but also on the ancient near east and egypt

backarc tectonism volcanism and mass wasting shape seafloor morphology in the santorini christiana amorgos region of the hellenic volcanic arc abstract in subduction zone backarcs extensional deformation and arc volcanism interact and these processes together with mass wasting shape the seafloor morphology we present a new bathymetric map of the santorini christiana amorgos backarc region of the hellenic subduction zone by merging high resolution multibeam swath data from the r v langseth proteus seismic experiment with existing maps the map together with knudsen subbottom echosounding profiles reveal that recent tectonism volcanism and mass wasting are more prevalent in the santorini amorgos region on the east side of santorini than in the christiana basin on the west side in the santorini amorgos region large normal faults form the anydros and anafi basins where normal fault segments overlap two nearby accommodation zones generate a relay ramp and the adjoining anydros synclinal horst with associated complex faulting and elevated seismicity the ongoing normal faulting in the santorini amorgos region is accompanied by potentially tsunamigenic submarine landsliding we identified a large submarine landslide along the santorini amorgos fault and a smaller landslide with an overlying debris chute along the amorgos fault volcanic activity is also focused in this eastern region along the kolumbo lineament within the anydros basin within the christiana basin we discovered the proteus knoll and adjacent buried edifice we suggest that this is an older volcanic edifice formed along the hellenic volcanic arc between santorini and milos around santorini itself features formed during and immediately after the late bronze age eruption dominate the seafloor morphology such as the northern strait and wrinkled seafloor pyroclastic flow deposits this topography is continually reshaped at a smaller scale by ongoing mass wasting we infer that the earthquake volcanic and tsunami activity of the santorini amorgos region is a consequence of focused northwest southeast extension as the southeastern aegean moves away from the attico cycladic complex in response to slab breakup and rollback

rock magnetic property and paleointensity determination on historical santorini lava flows eight historical dacitic lava flows from santorini with ages between 46 a d and 1950 a d four of them within the past century have been subjected to detailed rock magnetic analyses and various experiments of absolute paleointensity thermomagnetic measurements and acquisition of isothermal magnetization have revealed the presence of two physically distinct magnetic phases with curie temperatures of 280 c and 500 c in most of the samples the second phase does not play a prominent role for the characteristic remanent magnetization which is dominated by titanomagnetite magnetostatic interaction is very limited and does not considerably change upon heating back field curve spectra indicate a good thermochemical stability of these dacitic lava samples which is also supported by the absence of noticeable changes in the remanent coercive force prior heating to 450 c hysteresis measurements show typical pseudo single domain behavior without noticeable superparamagnetism such characteristics were favorable to conduct and to test the most widely used experimental approaches for absolute paleointensity determination despite a success rate of 38 the microwave technique has provided rather scattered within flow determinations the results obtained from approaches involving alternating field demagnetization were biased by considerable differences between the nrm and the trm coercive force spectra we have also noticed that most determinations obtained by microwave heating differ from the historical field value at the site for the most recent flows last techniques involving double heating protocols were successful due to a dominant low curie temperature phase with a narrow grain size distribution the results were characterized by low dispersion and were found in good agreement with the historical field

evidence from cosmic ray exposure cre dating for the existence of a pre minoan caldera on santorini greece cosmic ray exposure cre dating was performed on the caldera cliffs of santorini with the aim of detecting cliff segments predating the minoan eruption 17th century bce the methodology involved the determination of in situ produced cosmogenic 36cl concentration in basaltic to rhyodacitic whole rocks cropping out in the cliffs after the samples were processed following the chemical protocol of 36cl preparation for silicate rocks 36cl concentrations were measured by accelerator mass spectrometry ams important challenges during the implementation procedure were related to large amounts of radiogenic 36cl complex modeling of inherited 36cl and dominance of the thermal and epithermal low energy neutron capture production pathway nevertheless quantitative assessments on the basis of the contribution of the low energy neutron capture pathway percent to the total production rate validated the calculated cre dates current cre ages demonstrate that an ancient caldera existed on pre minoan santorini occupying at least the northern half of the modern day caldera

glacial advances and stratigraphy in otto fiord and adjacent areas ellesmere island northwest territories hvitland and svartfjeld peninsulas have been glaciated at least two or three times since the late pliocene the earliest recognized glaciation is constrained by amino acid ratios on in situ pelecypods from marine sediments stratigraphically overlying till in otto fiord high amino acid ratios suggest that the shells may be pliocene and related to recently discovered late pliocene hvitland beds at white point the same samples yielded finite radiocarbon ages in the 30 2 34 8 ka bp range which cautions against their acceptance a second mid quaternary glaciation is suggested by intermediate amino acid ratios from in situ pelecypods and shell bearing till covering coastal uplands along nansen sound during the last glaciation the peninsula was covered by coalesced ice caps with glacial tongues descending tributary valleys and extending into the fiords deglaciation of a tributary valley in outer otto fiord proceeded before 11 6 ka bp and before 9 1 ka bp in mid otto fiord but major ice margins remained a

new light on old pumice the origins of mediterranean volcanic material from ancient egypt this paper presents and discusses the neutron activation analysis naa results newly obtained from pumice pieces found decades ago at the egyptian sites of maiyana sedment kahun and amarna now in the collections of the ashmolean museum oxford and the petrie museum of egyptian archaeology london which could be successfully related to several volcanic eruptions in the mediterranean the work contributes to the constant accumulation of knowledge concerning the first appearance of pumice from the so called minoan eruption of the santorini volcano in addition it unexpectedly sheds more light on the long distance trade of mediterranean volcanic material in the bronze age world by disclosing another connection between lipari and the eastern mediterranean

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

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

tephrostratigraphy chronology and climatic events of the mediterranean basin during the holocene an overview the identification and characterisation of high frequency climatic changes during the holocene requires natural archives with precise and accurate chronological control which is usually difficult to achieve using only 14c chronologies the presence of time spaced tephra beds in quaternary mediterranean successions represents an additional independent tool for dating and correlating different sedimentary archives these tephra layers are potentially useful for resolving long standing issues in paleoclimatology and can help towards correlating terrestrial and marine paleoclimate archives known major tephras of regional extent derive from central and southern italy the hellenic arc and from anatolia a striking feature of major holocene tephra deposition events in the mediterranean is that they are clustered rather than randomly distributed in time several tephra layers occurred at the time of the s1 sapropel formation between c 8 4 and 9 0 ka bp mercato gabellotto fiumebianco e1 cappadocia and ot

northwestward decline of magnetic susceptibility for the red clay deposit in the chinese loess plateau 1 the loess paleosol red clay sequence in the chinese loess plateau has attracted attention for its potential in recording late cenozoic climatic changes over northern china although the details of the climatic implications of the proxies for example magnetic susceptibility and the reconstructed summer monsoon changes remain unclear here we report on a new section from baishui in gansu province and compare it with the lingtai and jingchuan sections by correlating the magnetic susceptibility from these sections we show that there is a clear systematic decrease of the magnetic susceptibility in the red clay deposits from the southeast lingtai section to the northwest baishui section this result suggests that the climatic parameters probably precipitation had a decreasing northwestward gradient during the red clay deposition this climatic pattern is similar to the present condition implying that the influence of the east asian summer monsoon on the chinese loess plateau has persisted from at least 6 ma

late glacial holocene climate variability at the south eastern margin of the aegean sea abstract new micropaleontological palynological and geochemical results from a relatively shallow 500 m sediment core ns 14 in the south eastern aegean sea provide a detailed picture of the regional expression of sapropel s1 formation in this sub basin of the eastern mediterranean sea specifically freshwater input during 10 6 10 0 ka bp has preceded the deposition of s1 further decrease in surface water salinity is evidenced between 10 0 and 8 5 ka bp at the lower part of s1a which in respect to s1b is featured by warmer 19 5 c and more productive surface waters associated with dysoxic bottom conditions a series of coolings detected within the s1 depositional interval may be linked to outbursts of cold northerly air masses and relevant pulses in the deep intermediate water ventilation that caused the s1 interruption between 7 9 and 7 3 ka bp and culminated during the deposition of s1b with the decline of deep chlorophyll maximum dcm at 6 5 ka bp the climate instability and the relevant absence of anoxia weakened the organic matter preservation in the shallow south eastern aegean margin during the s1 times ns 14 record provides evidence for a distinct mid holocene warm up to 25 c and wet phase associated with the deposition of the sapropel like layer smh sapropel mid holocene between 5 4 and 4 3 ka bp the smh layer could represent evidence of on going albeit weak african monsoon forcing only expressed at the south eastern edge of the aegean sea its end is associated with the 4 2 ka bp northern hemisphere mega drought event and the termination of the african humid period at 3 8 ka bp

constraining the landscape of late bronze age santorini prior to the minoan eruption insights from volcanological geomorphological and archaeological findings abstract one of the best known places on earth where volcanology meets archaeology and history is the volcanic island of santorini thira greece it is famous for the cataclysmic late bronze age minoan plinian eruption which destroyed the minoan culture that flourished on the island hosting a central flooded caldera bay and within that the active islands of palaea and nea kameni santorini volcano has been the focus of international research efforts for over one and a half centuries in this paper we summarize recent findings and related ideas about the minoan physiography of the island also known as strongyli from a volcanological geomorphological and archaeological point of view as proposed as early as the 1980s a central caldera bay existed prior to the late bronze age probably characterised by a smaller size and located in the northern part of the present day caldera this earlier caldera bay was formed during the previous plinian eruption called cape riva eruption c 22 000 years ago within the caldera bay a central island pre kameni existed named after the present day kameni islands high precision radioisotopic dating revealed that pre kameni started to grow c 20 000 years ago whereas volcanologists have accepted and refined the caldera concept archaeologists have generally favoured the theory of an exploded central cone instead of a pre existing central caldera however analysis of the flotilla fresco one of the wall paintings found in the bronze age settlement of akrotiri reveals the interior of a late bronze age caldera that may be interpreted as a realistic landscape approximately 3600 years ago the island of strongyli was destroyed during the explosive vei 7 minoan eruption pre kameni was lost by this eruption but its scattered fragments together with other parts of strongyli can be recovered as lithic clasts from the minoan tuffs on the basis of photo statistics and granulometry of the lithic clasts contained in the minoan tuffs complemented by volumetric assessment of the erupted tephra and digital elevation model dem analysis of alternative models for the pre eruptive topography the volume of pre kameni can be constrained between 1 6 and 3 0 km3 whereas the volume of the destroyed portion of the ring island of strongyli between 9 1 and 17 1 km3 of these the larger values are considered more realistic and imply that most of the destroyed part of strongyli was incorporated as lithic components in the minoan tuffs whereas up to 3 km3 of strongyli might have been downfaulted and sunken during caldera formation and is not accounted for in the lithics

recent geodetic unrest at santorini caldera greece 1 after approximately 60 years of seismic quiescence within santorini caldera in january 2011 the volcano reawakened with a significant seismic swarm and rapidly expanding radial deformation the deformation is imaged by a dense network of 19 survey and 5 continuous gps stations showing that as of 21 january 2012 the volcano has extended laterally from a point inside the northern segment of the caldera by about 140 mm and is expanding at 180 mm yr a series of spherical source models show the source is not migrating significantly but remains about 4 km depth and has expanded by 14 million m3since inflation began a distributed sill model is also tested which shows a possible n s elongation of the volumetric source while observations of the current deformation sequence are unprecedented at santorini it is not certain that an eruption is imminent as other similar calderas have experienced comparable activity without eruption

karst depressions as geoarchaeological archives the palaeoenvironmental reconstruction of zominthos central crete based on geophysical prospection sedimentological investigations and gis abstract sediment filled karst depressions e g dolines have rarely been used as geoarchives in greece due to an uncertainty about the thickness of accumulations and their vague suitability for palaeoenvironmental research however such terrestrial proxy data sources can yield important records for the analysis of the holocene landscape history a multi method approach was applied in order to evaluate the potential of colluvial fillings for reconstructing the geoarchaeological landscape in mount ida central crete subsequent to an area wide survey of appropriate karst hollows through remote sensing and gis analyses geophysical prospection refraction seismics earth resistivity tomography was conducted at the most promising archive locations selective percussion drilling within the sinkholes provided vibra cores for mineralogical and sedimentological investigations grain size distribution heavy and light minerals x ray diffraction thin sections as well as ams 14 c dates as demonstrated by the results the dolines are partially filled by loose material up to 20 m b s and thus offer valuable information about the environmental history the diversified sediment constitution indicates several geomorphodynamic oscillations and a polygenetic nature of the colluvial fills xrd spectra of clay minerals and quartz grain morphology both indicate a significant aeolian dust contribution to soil formation and pedo sediments glass shards and substantially heterogeneous heavy mineral compositions point to supra regional origin and external volcanogenic deposits minoan eruption of santorini 3 6 ka regarding the hitherto discussed distribution of z2 tephra in the mediterranean the spatial fallout must be revised as great amounts have also been deposited in the high mountains of crete moreover the redeposition of the sedimentary fills proves to be comparatively young since most materials were accumulated within the dolines post eruptively huge and previously unknown subsurface archaeological remains strongly suggest that year around settlement in the mid holocene might have been possible under better climatic conditions the results imply that karst depressions serve as suitable geoarchives particularly when investigated within a multi method approach

tephra in caves distal deposits of the minoan santorini eruption and the campanian super eruption abstract tephra deposits in caves are not only significant as stratigraphic markers the comparatively sheltered position of cave environments protected from rainfall may preserve original distal tephra deposition features unlikely to have survived in the open landscape most reported findings of tephra in caves are from the campanian super eruption which originated in the area of naples italy these findings facilitate evaluation in different caves of facies variability and modes of tephra deposition derived from the same eruption the campanian volcanic event about 40 000 years ago was the largest eruption in europe and the mediterranean region during the late pleistocene another major volcanic event during the quaternary was the more recent santorini eruption in the eastern mediterranean aegean sea during the late minoan cultural period approximately 3600 years ago this was the largest holocene eruption in the region but tephra deposits in caves from this event appear to be very rare we present here the first ever finding of a visible tephra layer from the minoan santorini eruption in a cave the pure tephra situated in the pelekita cave in eastern crete near kato zakros has a thickness of up to 9 cm geochemistry analyses of major elements by electron probe micro analysis epma and trace elements by laser ablation inductively coupled plasma mass spectrometry la icp ms prove the tephra to be derived from the minoan santorini eruption radiocarbon dating also fits the time frame of this eruption our findings indicate that the tephra layer in the pelekita cave is an air fall deposit the lower boundary of the tephra layer is sharp and wavy draping over the underlying irregular cave surface particle size distribution of the tephra is bimodal and typical for suspended aeolian transport the consistently smaller size of heavier feldspar particles adjacent to larger but lighter volcanic glass particles in thin sections of undisturbed samples corroborate emplacement of the tephra inside the pelekita cave from high altitude fallout

the early to mid holocene marine tephrostratigraphic record in the nisyros yali kos volcanic center se aegean sea abstract the kos nisyros yali volcanic region is one of the centers in the south aegean volcanic arc to exhibit holocene volcanic activity with poorly dated thin tephra layers on yali associated with neolithic artifacts this paper helps to resolve the age and character of early to mid holocene volcanism in the south aegean sea it presents the lithostratigraphic record of seven newly recovered cores from this region at the se termination of the south aegean volcanic arc the cores were scanned for magnetic susceptibility split logged and sampled at one centimeter resolution for carbonate content selected intervals were analyzed for grain size organic carbon content and feldspar content by xrd in order to identify lithostratigraphic levels with enhanced volcanic minerals subsequently textural and electron microprobe analyses of volcanic glass shards and pumice fragments were carried out on 20 samples chronology was inferred from the upper and lower limits of the s1 sapropel and from five ams 14c dates on foraminifera in several cores in the s1 interval mixed volcanic glass types that compositionally correlate with the nisyros lower and upper pumice yali pumices and kpt suggest that the volcanic glass is reworked from previous deposits and transported by turbidity currents cores from deep water northeast and northwest of yali have a single population of tephra at two or more horizons within s1 that geochemically resembles holocene yali 4 pumice on land these beds likely represent air fall ash that was dispersed at least 10 km from yali with ages of 8 and 10 ka moreover we report two or more tephra layers within s1 from the kalymnos basin that are not reworked and geochemically resemble santorini tephra this study thus confirms the occurrence of small early holocene eruptions at yali and provides possible evidence for early holocene eruptions at santorini

the cultural nature of tephra problematic ecofacts and artifacts and the baru volcano panama abstract this paper presents data from archaeological stratigraphy and lacustrine core samples containing tephra from the baru volcano in western panama the discussion seeks to refine the understanding of medial tephra deposits near baru in relation to the eruption history indicated by geological palaeoecological and archaeological data a primary goal of this fieldwork is the identification and correlation of tephra from major baru eruptions encountered in archaeological contexts by their lithology stratigraphic position and mineralogy without resorting to geochemical fingerprinting the intention is to develop a cost efficient and reproducible means of utilizing tephra as a chronostratigraphic marker in archaeological contexts and examine the intersection of human life with volcanic events and dynamic environments tephra in archaeological contexts can have ambiguous placement between ecofact and artifact as is the case with a small number of crude tephra sculptures in my excavated material and that of a seminal prior study while the research project utilizes visible tephra layers not cryptotephra by all means the tephra data prove to be cryptic engagement with the imperfection entailed in meshing multidisciplinary data sets and different scientific communities with interests in tephra particularly in lesser studied regions is posited as a total view of tephra

late quaternary tephra layers along the cilento coastline southern italy abstract the results of stratigraphic and tephrostratigraphic analyses of several pyroclastic levels collected along the coastal sector of the cilento region southern italy are presented some of these levels are here described for the fist time others already known in literature were reconsidered in order to better understand their stratigraphic position and to point out the possible volcanic sources the main outcrops are located along the southern coast of the campania region cilento coast all pyroclastic layers are interbedded within coastal or continental successions younger than the substage 5e of the last interglacial the results of sem eds analyses on well preserved glass fragments indicate a composition falling between the trachyte and phonolite fields of the tas plot as typical of phlaegrean fields products by comparing their composition with those of the main tephra marker layers recorded in southern italy the correlation of the cilento pyroclastic layers with well known eruptive episodes was hypothesised in summary four different eruptions were recognised the first one is testified by a pyroclastic layer not correlated with a terrestrial counterpart covered by a middle pleistocene alluvial fan the second one is the eruptive event emplacing the x 6 marker tephra layer and dates around 107 ka the third is the campanian ignimbrite eruption 39 ka and the last one is testified by the layers correlated with the y 3 tephra about 30 ka these pyroclastic layers can be useful tools for stratigraphic correlations of late quaternary successions in southern italy

combining historical and 14 c data to assess pyroclastic density current hazards in banos city near tungurahua volcano ecuador pyroclastic density currents pdcs from tungurahua volcano ecuador recurrently rush down the northern vazcun valley and threaten the small tourist city of banos located on its mouth estimating pdc hazards i e pdc return rate and extent is difficult in banos and vazcun because data from the literature are rare and debated while geological exposures are few and vegetated to improve our awareness of pdc hazards in the banos area we examined historical documents conducted new geological research in the vazcun valley and obtained additional 14c data we highlight complex radiocarbon results that may lead to difficulties when interpreting the pdc chronology and offer recommendations to improve sampling strategies for 14c age determinations of pdc deposits overall our results show that the 1640 1773 and 1886 pdc forming eruptions are recorded in the valley while products of the 1918 and 2006 events were likely removed through considering recorded unrecorded bias in the reconstruction of past pdc emplacement in vazcun we calculate a minimal average return rate of 18 pdc forming events for pre columbian and historical eruptions since the devastating 3 ka bp eruption which translates into a maximum average return rate of 150 200 years in the valley however the archives suggest that most pdcs did not affected the now urbanized banos area e g 1918 2006 and we estimate that the city is impacted on average every 350 500 years a duration that is likely perceived as fairly long for people living in the area the banos case study thus raises questions on how to communicate on uncertain threats and impacts and how to improve alert messages in a town where economic incomes are essentially based on tourist activities to better address these issues we plan in future works to focus on cognitive perception of risk and volcanic hazard judgment by populations of banos and nearby rural communities

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

correlating tephras and cryptotephras using glass compositional analyses and numerical and statistical methods review and evaluation abstract we define tephras and cryptotephras and their components mainly ash sized particles of glass crystals in distal deposits and summarize the basis of tephrochronology as a chronostratigraphic correlational and dating tool for palaeoenvironmental geological and archaeological research we then document and appraise recent advances in analytical methods used to determine the major minor and trace elements of individual glass shards from tephra or cryptotephra deposits to aid their correlation and application protocols developed recently for the electron probe microanalysis of major elements in individual glass shards help to improve data quality and standardize reporting procedures a narrow electron beam diameter 3 5 m can now be used to analyze smaller glass shards than previously attainable reliable analyses of microshards defined here as glass shards in part 2 of the review we describe critically assess and recommend ways in which tephras or cryptotephras can be correlated in conjunction with other information using numerical or statistical analyses of compositional data statistical methods provide a less subjective means of dealing with analytical data pertaining to tephra components usually glass or crystals phenocrysts than heuristic alternatives they enable a better understanding of relationships among the data from multiple viewpoints to be developed and help quantify the degree of uncertainty in establishing correlations in common with other scientific hypothesis testing it is easier to infer using such analysis that two or more tephras are different rather than the same adding stratigraphic chronological spatial or palaeoenvironmental data i e multiple criteria is usually necessary and allows for more robust correlations to be made a two stage approach is useful the first focussed on differences in the mean composition of samples or their range which can be visualised graphically via scatterplot matrices or bivariate plots coupled with the use of statistical tools such as distance measures similarity coefficients hierarchical cluster analysis informed by distance measures or similarity or cophenetic coefficients and principal components analysis pca some statistical methods cluster analysis discriminant analysis are referred to as machine learning in the computing literature the second stage examines sample variance and the degree of compositional similarity so that sample equivalence or otherwise can be established on a statistical basis this stage may involve discriminant function analysis dfa support vector machines svms canonical variates analysis cva and anova or manova or its two sample special case the hotelling two sample t2 test randomization tests can be used where distributional assumptions such as multivariate normality underlying parametric tests are doubtful compositional data may be transformed and scaled before being subjected to multivariate statistical procedures including calculation of distance matrices hierarchical cluster analysis and pca such transformations may make the assumption of multivariate normality more appropriate a sequential procedure using mahalanobis distance and the hotelling two sample t2 test is illustrated using glass major element data from trachytic to phonolitic kenyan tephras all these methods require a broad range of high quality compositional data which can be used to compare unknowns with reference training sets that are sufficiently complete to account for all possible correlatives including tephras with heterogeneous glasses that contain multiple compositional groups currently incomplete databases are tending to limit correlation efficacy the development of an open online global database to facilitate progress towards integrated high quality tephrostratigraphic frameworks for different regions is encouraged

speleothems as sensitive recorders of volcanic eruptions the bronze age minoan eruption recorded in a stalagmite from turkey mounting evidence exists that variations in sulphur content in stalagmites are closely linked to changes in volcanic or anthropogenic atmospheric sulphur the strong dependency of sulphur on soil ph and ecosystem storage however can result in a delay of several years to decades in the registration of volcanic eruptions and anthropogenic emissions by stalagmites here we present synchrotron radiation based trace element analysis performed on a precisely dated section of a stalagmite from sofular cave in northern turkey as this section covers the time interval of the intensively studied minoan volcanic eruption between 1600 and 1650 bc we can test whether this vigorous eruption can be traced in a stalagmite of all measured trace elements only bromine shows a clear short lived peak at 1621 251621 25 bc whereas sulphur and molybdenum show peaks later at 1617 251617 25 and 1589 251589 25 respectively we suggest that all trace element peaks are related to the minoan eruption whereas the observed phasing of bromine molybdenum and sulphur is related to differences in their retention rates in the soil above sofular cave for the first time we can show that bromine appears to be an ideal volcanic tracer in stalagmites as it is a prominent volatile component in volcanic eruptions can be easily leached in soils and rapidly transferred from the atmosphere through the soil and bedrock into the cave and stalagmite respectively highly resolved oxygen and carbon isotope profiles indicate that the minoan eruption had no detectable climatic and environmental impact in northern turkey

the detailed tephrostratigraphy of a core from the south east black sea spanning the last 60 ka one visible volcanic ash layer and 21 non visible cryptotephra horizons have been identified in the m72 5 25 gc1 core from the south east black sea that spans the last 60 ka glass chemistry suggests that the tephras derive from italian hellenic and turkish sources the visible tephra layer is trachytic in composition and has been correlated to the 39 ka campanian ignimbrite super eruption from campi flegrei caldera italy two cryptotephra layers are associated with eruptions from acigol volcano turkey around the last glacial maximum another is linked to activity at erciyes dagi in the early holocene perikartini or karagullu and a cryptotephra layer near the top of the core correlates to the 3 6k cal a bp minoan marine z2 tephra from santorini thera greece this extends the known dispersal area for all these volcanic ash units many other calc alkaline rhyolite layers preserved in the core are likely to be from central anatolian sources but the lack of detailed proximal data for many of the volcanoes in the region prohibits further correlations the tephrostratigraphy and glass compositional data presented here allow the tephra layers to be used to correlate sedimentary archives across the region and help to extend the mediterranean tephrochronology framework towards the east