tephrostratigraphy of paleoclimatic archives in central mediterranean during the bronze age abstract re examination of central mediterranean paleoclimate archives on tephra layers indicates that three widely dispersed tephra layers occurred during the bronze age namely agnano mt spina from campi flegrei ca 4 4 cal ka bp avellino from somma vesuvius ca 3 9 cal ka bp and fl from etna ca 3 3 cal ka bp stratigraphical correlations of selected archives using these tephra layers indicate that some records have severe chronological biases posing important limitations to the use of these archives for defining the paleoclimate conditions during the bronze age regardless of the temporal mismatches the agnano mt spina tephra layer seems to have occurred at the beginning of a centennial scale period of climatic deterioration while the avellino tephra layer taking place during a wetter period seems to mark the end of this event the dry event bounded by the two tephra layers seems to be correlated with the so called 4 2 event instead the fl tephra from etna seems to herald a new climatic deterioration at ca 3 3 3 2 cal ka bp although the general frame is still incomplete these three tephra layers appear to play a fundamental role in synchronizing archives and can lead to the definition of a detailed paleoclimatic framework of the bronze age in the central mediterranean area

quantitative assessment of volcanic ash hazards for health and infrastructure at mt etna italy by numerical simulation abstract we performed a quantitative hazard assessment to determine the potential impacts of volcanic tephra fall on human health and infrastructure in the vicinity of mt etna italy using the numerical model vol calpuff we explored the dynamics of long lasting weak plume eruptions and their effects on the surrounding region input data are based on credible estimates of the main parameters characterising the expected events as derived from the historically observed and reconstructed explosive record of mt etna monte carlo techniques are used to capture the effects on estimates of finer ash concentration and total ground deposition due to volcanological uncertainties and meteorological variability numerical simulations compute the likelihoods of experiencing critical 10 m volcanic particle vp 10 concentrations in ambient air and tephra ground deposition at various populated locations around the volcano including the city of catania and at key infrastructure such as airports and main roads results show how the towns and infrastructure on the east side of the volcano are significantly more exposed to ash related hazards than those on the west side in accordance with wind statistics simulation outcomes also illustrate how at the sites analysed the amount of deposited particulate matter is proportional to the intensity i e mass flow rate of the event whereas predicted values of vp 10 concentrations are significantly larger for smaller events due to the reduced dispersal of low altitude plumes the use of a simple re mobilization model highlights the fact that particle re suspension needs to be considered in the estimation of vp 10 values our findings can be used to inform civil protection agencies responsible for mitigating tephra fall impacts to human health road transport and aviation safety

the last 40 ka tephrostratigraphic record of lake ohrid albania and macedonia a very distal archive for ash dispersal from italian volcanoes abstract a 1075 cm long core lz1120 was recovered in the south eastern part of the lake ohrid republics of macedonia and albania and sampled for identification of tephra layers magnetic susceptibility investigations show rather high magnetic values throughout the core with peaks unrelated to the occurrence of tephra layers but instead to the relative abundance of detrital magnetic minerals in the sediment naked eye inspection of the core allowed us to identify of two tephra layers at 896 897 cm and 1070 1075 cm laboratory inspection of the grain size fraction 125 m allowed for the identification of a third cryptotephra at 310 315 cm major element analyses on glass shards of the tephra layers at 896 897 cm and 1070 1075 cm show a trachytic composition and indicate a correlation with the regionally dispersed y 3 and y 5 tephra layers dated at ca 30 and 39 cal ka bp the cryptotephra at 310 315 cm has a mugearitic benmoreitic composition and was correlated with the fl eruption of mt etna dated at 3370 70 cal yr bp these ages are in agreement with five 14 c ams measurements carried out on plant remains and macrofossils from the lake sediments at different depths along the core the recognition of distal tephra from italian volcanoes allows us to link the lake ohrid succession to other archives located in the mediterranean area and in eastern europe the benmoreitic mugearitic tephra layer at 310 315 cm is the first recognition in the balkan area of a distal ash deposit from a mid intensity explosive eruption of mt etna as far as 600 km from the source

constraints on the frequency and dispersal of explosive eruptions at sambe and daisen volcanoes south west japan arc from the distal lake suigetsu record sg06 core abstract accurately evaluating the tempo and magnitude of pre historic eruptions is essential for hazard assessments here we demonstrate the importance of integrating records from locations close to the volcano with those in distal regions to generate more comprehensive event stratigraphies the annually laminated varved and intensely radiocarbon dated lacustrine sediments of lake suigetsu sg06 core japan are used to place chronological constraints on the tempo of volcanism at two stratovolcanoes located favourably upwind of the lake along the south west japan arc sambe and daisen major and trace element glass compositions are used to assign visible ash tephra layers preserved in the sg06 sediment core to past explosive eruptions from these volcanoes integrating these stratigraphies confirm that the 150 ka long lake sequence records nine visible ash layers from daisen and five from sambe the sg06 record captures two periods of closely spaced eruptions at daisen volcano the first period begins at 61 1 ka with three explosive eruptions over 10 ka with two events separated by as little as 1 5 ka one layer sg06 4281 dated at 59 6 5 5 ka 95 4 probability relates to the large magnitude and widely dispersed daisen kurayoshi pumice dkp eruption the other period of frequent activity began at 29 837 96 intcal13 yrs bp 95 4 probability with five widely dispersed ash fall events associated with explosive eruptions separated by approximately 6 936 5 and 438 years the integrated proximal distal event stratigraphy and the high precision sg06 chronology provide unique insights into the timing and frequency of past explosive volcanism from daisen and sambe which has implications for the prediction of future eruption scenarios

the impact of the 1991 mount pinatubo tephra fallout on the geochemical environment of the deep sea sediments in the south china sea abstract seven years after the 1991 mount pinatubo eruption the current geochemical environment of ash covered deep sea sediments in the south china sea was investigated the depth distributions of o2 no3 mn2 corg and porosity at six representative sites covered with varying thicknesses of tephra are reported the shapes of the depth profiles reveal that o2 is totally exhausted within ash layers thicker than 3 cm while thinner layers are penetrated by oxygen followed by linear downcore profiles with depletion between 8 and 12 cm hence the zone between ash layer and total depletion of oxygen represents a zone of negligible oxygen consumption various multi layer models were developed to explain the observed oxygen concentration profiles these mathematical simulations also serve to assess both the development since the surface sediments were sealed by the ash fallout as well as the future evolution whereas thick tephra layers provoke a nearly stationary situation i e are capable of preventing oxygen from penetrating into the underlying sediments oxygenation of sediments below thin layers increases rapidly in these sediments the effect of oxygen diffusion velocity is drastically reduced by the reaction with dissolved manganese and therefore explains the linear profiles besides this study is suitable as a case study to assess the effects of human interventions in the deep sea ecosystem such as mining and waste dumping

a diverse ecosystem response to volcanic aerosols unexpectedly high aluminium concentrations beside fluoride and essential elements are released from metal salts adsorbed to volcanic ash through simulation of the mixing of pristine volcanic ash leachate with fresh water and seawater using phreeqc we found an increased potential toxicity in fresh waters through the combination of high aluminium and fluoride concentrations owing to the mixing of acid ash leachate with fresh water aluminofluoride complexes alfx 3 x persist in aqueous systems with low turnover rates and could be toxic to both plants and animals in contrast due to the well buffered and relatively high ph in seawater the speciation of the ash leachate seawater mixture shows that complexes of fluoride and aluminium i e alfx 3 x will not dominate in a well mixed marine system instead al oh x 3 x species will occur at greatest concentration consequently compared with fresh water environments the mixing of ash leachate with seawater indicates reduced toxic effects due to decreased formation of alfx 3 x complexes and the low solubility of al hydroxides in addition the deposition of volcanic aerosols may enhance biological activity in the marine environment by providing micronutrients as some oceanic phytoplankton species tolerates extreme concentrations of fluoride f

the late holocene tephra record of the central mediterranean sea mapping occurrences and new potential isochrons for the 4 4 2 0 ka time interval five cores from the southern tyrrhenian and ionian seas were studied for their tephra and cryptotephra content in the 4 4 2 0 ka time interval the chronological framework for each core was obtained by accelerator mass spectrometry 14c dating the occurrence of distinct marker tephra and stratigraphic correlation with adjacent records tephrochronology allowed us to correlate the analyzed deposits with tephra markers associated with somma vesuvius 79 ad ischia island cretaio mt etna fg fl and fs and campi flegrei astroni agnano monte spina events for the first time in the marine setting a large single glass data set is provided for the late holocene etnean marker beds including the fs tephra ca 4 3 ka moreover unknown deposits from lipari ca 2 2 2 0 ka and vulcano 3 6 3 3 ka are also recognized at more distal sites than previously reported these results contribute to improve the high resolution tephrostratigraphic framework of the central mediterranean sea they also provide new insights into the chemical composition and dispersal pattern of tephras that can be used as inter archive tools for regional and local stratigraphic correlations and for addressing paleoclimate research

environmental hazards of fluoride in volcanic ash a case study from ruapehu volcano new zealand abstract the vent hosted hydrothermal system of ruapehu volcano is normally covered by a c 10 million m3 acidic crater lake where volcanic gases accumulate through analysis of eruption observations granulometry mineralogy and chemistry of volcanic ash from the 1995 1996 ruapehu eruptions we report on the varying influences on environmental hazards associated with the deposits all measured parameters are more dependent on the eruptive style than on distance from the vent early phreatic and phreatomagmatic eruption phases from crater lakes similar to that on ruapehu are likely to contain the greatest concentrations of environmentally significant elements especially sulphur and fluoride these elements are contained within altered xenolithic material extracted from the hydrothermal system by steam explosions as well as in residue hydrothermal fluids adsorbed on to particle surfaces in particular total f in the ash may be enriched by a factor of 6 relative to original magmatic contents although immediately soluble f does not show such dramatic increases highly soluble naf and casif6 phases demonstrated to be the carriers of available f in purely magmatic eruptive systems are probably not dominant in the products of phreatomagmatic eruptions through hydrothermal systems instead slowly soluble compounds such as caf2 alf3 and ca5 po4 3f dominate fluoride in these phases is released over longer periods where only one third is leached in a single 24 h water extraction this implies that estimation of soluble f in such ashes based on a single leach leads to underestimation of the f impact especially of a potential longer term environmental hazard in addition a large proportion of the total f in the ash is apparently soluble in the digestive system of grazing animals in the ruapehu case this led to several thousand sheep deaths from fluorosis

fine ash content of explosive eruptions abstract in explosive eruptions the mass proportion of ash that is aerodynamically fine enough to cause problems with jet aircraft or human lungs 50

robust date for the bronze age avellino eruption somma vesuvius 3945 10 calbp 1995 10 calbc we found bronze age lake sediments from the agro pontino graben central italy to contain a thin 2 3 cm continuous tephra layer composed of lithics crystals and minor volcanic glass tephrochronological and compositional constraints strongly suggest that this layer represents the avellino pumice eruption which has also been identified in central italian lake cores its provenance is corroborated by electron microprobe analyses performed on juvenile pumice grains showing that the tephra layer is probably the distal equivalent of the eu2 event of the avellino eruption we used multiple 14 c age estimations of two lacustrine sequences with intercalated tephra layer from the western border zone migliara 44 5 and the centre of the former lake campo inferiore for in tandem dating of this eruption employing the oxcal code which yielded a robust age of 3945 10 calbp 1995 10 calbc to date this is the only study providing both a terminus post and terminus ante quem of this precision also demonstrating the advantage of dating distal tephra layers in a clear stratigraphic context over proximal deposits in sequences with major stratigraphic hiatuses our new results underscore the importance of the avellino tephra layer as a precise time marker for studies on the early bronze age of central italy c 2011 elsevier ltd all rights reserved

the 1989 1990 eruption of redoubt volcano alaska impacts on aircraft operations abstract the december 1989 june 1990 eruption of redoubt volcano affected commercial and military air operations in the vicinity of anchorage alaska these effects were due to the direct impact of volcanic ash on jet aircraft as well as to the rerouting and cancellations of flight operations owing to eruptive activity between december and february five commercial jetliners were damaged from ash encounters the most serious incident took place on december 15 1989 when a boeing 747 400 aircraft temporarily lost power of all four engines after encountering an ash cloud as the airplane descended for a landing in anchorage while there were no injuries to passengers the damage to engines avionics and aircraft structure from this encounter is estimated at 80 million four additional encounters between jet aircraft and redoubt ash clouds occurred in the anchorage area on december 15 and 16 1989 and february 21 1990 none resulted in engine failure two additional encounters took place on december 17 1989 when jet airliners encountered the redoubt cloud over west texas at the time of these encounters the cloud was up to 55 hours old and had traveled in excess of 2 900 nautical miles 5 300 km following the december 15 encounters anchorage international airport remained open however most airline companies canceled operations for up to several days as communications between federal agencies and airlines improved and as a better understanding of the nature and behavior of ash rich eruption clouds was achieved most airlines resumed normal service by early january 1990 the resulting loss of revenue at anchorage international airport during several months following the eruption is estimated to total 2 6 million the impact on general aviation and military operations consisted mostly of cancellation and rerouting of flights

contamination of water supplies by volcanic ashfall a literature review and simple impact modelling abstract volcanic ash is the most widely distributed product of explosive volcanic eruptions and can disrupt vital infrastructure on a large scale previous studies of effects of ashfall on natural waters and water supplies have focused mainly on the consequences of increased levels of turbidity ash suspended in water acidity and fluoride with very little attention paid to other contaminants associated with volcanic ash the aims of this paper are twofold firstly to review previous studies of the effects of volcanic ashfall on water supplies and identify information gaps and secondly to propose a simple model for predicting effects of ashfall on water supplies using available information on ash composition we reviewed reported impacts of historic eruptions on water supplies drawing on case studies from new zealand vanuatu argentina the usa costa rica montserrat iceland and guadeloupe elevated concentrations of fluoride iron sulphate and chloride as well as turbidity and acidity have been reported in water supplies from a public health perspective the two main issues appear to be 1 outbreaks of infectious disease caused by the inhibition of disinfection by high levels of suspended ash and 2 elevated fluoride concentrations we devised a simple model using volcanic ash leachate composition data to predict effects on receiving waters applying this model to the effects of ruapehu ash from the 1995 1996 eruptions suggests that the primary effects of concern are likely to be an increase in acidity decrease in ph and increases in concentrations of the metals aluminium iron and manganese these metals are not normally considered to pose health risks and are regulated only by secondary non enforceable guidelines however exceedences of guideline values for al mn fe and ph will cause water to become undrinkable due to a bitter metallic taste and dark colour and may also cause corrosion staining and scale deposition problems in water tanks and pipes therefore the main issues following volcanic ashfall of similar composition to ruapehu ash are likely to be shortages of potable water and damage to distribution systems rather than risks to public health

linking tephrochronology and soil characteristics in the sila and nebrodi mountains italy recent studies have demonstrated that soils formed on pyroclastic ash deposits are much more common in the mediterranean area than previously assumed these soils are an important key to understanding past volcanic events and landscape evolution chronological information in soils of quaternary volcanic events however remains still poorly understood in southern italy using a multi method forensic approach we explore the origin and age of volcanic deposits soils in sicily and calabria the geochemical signature of the soil was compared to the chemical fingerprint of the magmas of potential source areas of southern italian volcanoes the results indicate that the investigated soils on the nebrodi sicily and sila calabria mountains were both impacted by materials having a high k calc alkaline series volcanism the aeolian islands in particular lipari and vulcano are the most likely source of origin but contributions also from the etna particularly the biancavilla ignimbrites and plinian eruptions occurred weathering and leaching processes along with a potential contribution from the underlying non volcanic bedrock has altered the main chemical composition of soils often precluding direct relation to potential source areas immobile elements and their ratios e g the nb y vs zr ti plot or trace elements co th and rare earth elements laser ablation icp ms analyses of glass particles volcanic clasts and pumice like materials gave precious hints of the origin of the volcanic deposits radiocarbon dating of the h2o2 resistant soil organic fraction indicates a minimum age of 8 10 ka of the soils the weathering index wip weathering index according to parker and the chemical composition of volcanic glasses and clasts were tested as proxies for the age of the volcanic deposits and time for soil formation the soils and landscape are characterised by multiple volcanic depositional phases for the last about 50 ka in the sila mountains and about 70 ka or more in the nebrodi mountains chemical mineralogical analyses enabled the detection of deposition phases during the pleistocene and also holocene the multi method approach enabled the identification of potential source areas provided a tentative age estimate of the start and in part duration of ash deposits and therefore improved our understanding of volcanic landscape evolution

2700 years of mediterranean environmental change in central italy a synthesis of sedimentary and cultural records to interpret past impacts of climate on society abstract abrupt climate change in the past is thought to have disrupted societies by accelerating environmental degradation potentially leading to cultural collapse linking climate change directly to societal disruption is challenging because socioeconomic factors also play a large role with climate being secondary or sometimes inconsequential combining paleolimnologic historical and archaeological methods provides for a more secure basis for interpreting the past impacts of climate on society we present pollen non pollen palynomorph geochemical paleomagnetic and sedimentary data from a high resolution 2700 yr lake sediment core from central italy and compare these data with local historical documents and archeological surveys to reconstruct a record of environmental change in relation to socioeconomic history and climatic fluctuations here we document cases in which environmental change is strongly linked to changes in local land management practices in the absence of clear climatic change as well as examples when climate change appears to have been a strong catalyst that resulted in significant environmental change that impacted local communities during the imperial roman period despite a long period of stable mild climate and a large urban population in nearby rome our site shows only limited evidence for environmental degradation warm and mild climate during the medieval warm period on the other hand led to widespread deforestation and erosion the ability of the romans to utilize imported resources through an extensive trade network may have allowed for preservation of the environment near the roman capital whereas during medieval time the need to rely on local resources led to environmental degradation cool wet climate during the little ice age led to a breakdown in local land use practices widespread land abandonment and rapid reforestation our results present a high resolution regional case study that explores the effect of climate change on society for an under documented region of europe

environmental effects of ashfall in argentina from the 2008 chaiten volcanic eruption analyses of air water and vegetation samples collected in june 2008 offer new insights into the environmental effects of the may 2008 chaiten eruption on argentina which was subject to significant ashfall between 42 s and 46 s results from air filtration in the ash affected town of esquel with samples analysed by gravimetry and scanning electron microscopy show the total mass of resuspended ash in the air is well correlated with traffic activity however this variation is primarily related to varying amounts of the largest particles with little variation in the amounts of fine ash particles i e d results from water and vegetation sampling with samples analysed by inductively coupled plasma mass spectrometry and ion chromatography indicate that ashfall resulted in significant compositional changes in ephemeral lakes and coiron grass festuca pallescens for b cd zn tl cu and ni there are strong linear correlations between concentrations and ash thickness where 2 mm in both datasets these results suggest that the eruption of chaiten led to significant changes in the concentrations of trace volatile elements within the environment analysis of vegetation samples collected in january 2009 indicates that the elevated element concentrations in coiron grass persisted for 8 months these results offer insights into the environmental fate of volatile trace elements emitted during volcanic eruptions

the postglacial record of environmental history from lago di pergusa sicily lacustrine sedimients from lago di pergusa in central sicily provide a postglacial record of environmental change in the mediterranean magnetic susceptibility measurements lithofacies characterization and pollen analysis were carried out anid integrated to obtain a better reconstruction of the past 11000 years the chronoogy is provided by ams radiocarbon dates on macrofossils or bulk sediment and by a tephra correlative with a late holocene explosion from the etna volcano the transition period related to the present interglacial reafforestation characterized by increasing humidity started about 10700 years bp the onset of the wettest conditions of the postglacial occurred at about 9000 years bp and lasted until about 7200 years bp then a trend towards aridification began leading to very dry conditions at about 3000 years bp an unquestionable human impact on vegetation is found from 2800 years bp although earlier land use cannot be excluded as the climate had already induced change in the vege

potential impacts from tephra fall to electric power systems a review and mitigation strategies modern society is highly dependent on a reliable electricity supply during explosive volcanic eruptions tephra contamination of power networks systems can com promise the reliability of supply outages can have signifi cant cascading impacts for other critical infrastructure sectors and for society as a whole this paper summarises known impacts to power systems following tephra falls since 1980 the main impacts are 1 supply outages from insulator flashover caused by tephra contamination 2 dis ruption of generation facilities 3 controlled outages during tephra cleaning 4 abrasion and corrosion of exposed equipment and 5 line conductor breakage due to tephra loading of these impacts insulator flashover is the most common disruption the review highlights multiple instan ces of electric power systems exhibiting tolerance to tephra falls suggesting that failure thresholds exist and should be identified to avoid future unplanned interruptions to ad dress this need we have produced a fragility function that quantifies the likelihood of insulator flashover at different thicknesses of tephra finally based on our review of case studies potential mitigation strategies are summarised specifically avoiding tephra induced insulator flashover by cleaning key facilities such as generation sites and trans mission and distribution substations is of critical importance in maintaining the integrity of an electric power system

tephrostratigraphy of the last 170 ka in sedimentary successions from the adriatic sea abstract in this study are discussed new sem eds analyses performed on glass shards from five cores collected in the central adriatic sea and two cores recovered from the south adriatic sea a total of 26 tephra layers have been characterized and compared with the geochemical features of terrestrial deposits and other tephra archives in the area south adriatic sea and lago grande di monticchio vulture volcano the compositions are compatible with either a campanian or a roman provenance the cores located on the central adriatic inner and outer shelf recorded tephra referred to explosive events described in the literature ap3 sub plinian activity of the somma vesuvius 2710 60 14 c years bp avellino eruption somma vesuvius 3548 129 14 c years bp agnano monte spina phlegrean fields 4100 400 years bp mercato eruption somma vesuvius 8010 35 14 c years bp agnano pomici principali eruption phlegrean fields 10 320 50 14 c years bp neapolitan yellow tuff phlegrean fields 12 100 170 14 c years bp some of these layers were also observed in the south adriatic core in68 9 in addition to younger ap2 sub plinian eruption somma vesuvius 3225 140 14 c years bp and older layers pomici di base eruption somma vesuvius 18 300 150 14 c years bp significant is the tephra record of core rf95 7 that for the first time in the adriatic sea reports the occurrence of tephra layers older than 60 ka the well known mediterranean tephra layers x2 ca 70 ka w1 ca 140 ka and v2 roman origin ca 170 ka as well as other tephra layers attributed on the basis of geochemistry and biostratigraphy to explosive eruptions occurred at vico 138 2 and 151 3 ka bp and ischia 147 140 ka bp previous tephra correlations performed on other cores in the central adriatic sea were also critically revised according to new available data and integrated with the results of this study for a correlation at a regional scale the most important key beds for correlation are the agnano monte spina and neapolitan yellow tuff tephra layers which occur in both central and south adriatic sea other tephra layers younger than 15 ka are relatively less frequent the y1 etna 14 180 260 14 c years bp and agnano pomici principali in the more recent record in the shelf cores north of gargano promontory the ap3 tephra layer is also frequent

total grain size distribution of components of fallout deposits and implications for magma fragmentation mechanisms examples from campi flegrei caldera italy in this paper we present results of the reconstruction of the total grain size distribution tgsd of the material erupted during explosive volcanic eruptions at campi flegrei italy considering all components juvenile lithic and crystal clasts to date the few tgsds made available have been mostly reconstructed by assuming that the tephra deposits consisted of only one component this simplification can introduce substantial bias in the interpretation of magma fragmentation mechanisms and significantly affect ash dispersion forecasts since each tephra component has specific aerodynamic characteristics by means of field investigations and laboratory analyses on samples collected from deposits of the agnano monte spina and astroni eruptions we reconstructed the tgsds of juvenile lithic and crystal components via the voronoi tessellation method our results show how the systematic reconstruction of a tgsd from the component specific to the bulk tgsd can provide important information on magma fragmentation mechanisms and wall rock erosion processes results confirm that the bulk tgsd is the combination of the merging of different component subpopulations according to their own tgsd density and relative mass proportions in addition the integration of component analysis tgsd and settling velocity data allowed characterization of the aerodynamic behaviour of each component at variable distances from the vent which can be related to their own parent grain size distribution the integration of new data from distal tephra deposits for the considered eruptions has thus allowed a reassessment of the erupted volumes of eruptions considered in this research which are now 3 17 and 0 63 km3 for agnano monte spina and astroni respectively

tephrostratigraphy study for the last 18 000 14 c years in a deep sea sediment sequence for the south adriatic abstract a detailed tephrostratigraphy supported by accelerator mass spectrometry ams 14c dating and isotopic and geochemical analyses has been carried out for a deep sea core collected from the southern adriatic sea which spans the last 18 14c kyr fourteen ash layers have been recognized in the marine core and the origin was determined by comparing their age and geochemistry with tephra detected in terrestrial deposits the geochemical signatures of marine ash layers indicate a prevailing campanian and subordinate etnean and eolian provenances collectively they are attributed to sources in the phlegraean fields lam lagno amendolare ln1 ln2 gm1 c 2 nyt neapolitan yellow tuff c 1 agnano pomici principali ams pf agnano monte spina ast astroni somma vesuvius l9 pomici di base l8 greenish mount etna et1 y1 biancavilla ignimbrite lipari e 1 gabellotto fiumebianco and palinuro seamount pal 1 some of these eruptions have been detected for the first time in marine cores astroni lam l9 l8 and three were detected and dated by marine tephra ln1 ln2 and pal 1 providing new more precise stratigraphic markers for the last 18 kyr in the south adriatic marine record

a model for wet aggregation of ash particles in volcanic plumes and clouds 2 model application 1 the occurrence of particle aggregation has a dramatic effect on the transport and sedimentation of volcanic ash the aggregation process is complex and can occur under different conditions and in multiple regions of the plume and in the ash cloud in the companion paper costa et al develop an aggregation model based on a fractal relationship to describe the rate particles are incorporated into ash aggregates the model includes the effects of both magmatic and atmospheric water present in the volcanic cloud and demonstrates that the rate of aggregation depends on the characteristics of the initial particle size distribution the aggregation model includes two parameters the fractal exponent df which describes the efficiency of the aggregation process and the aggregate settling velocity correction factor e which influences the distance at which distal mass deposition maxima form both parameters are adjusted using features of the observed deposits here this aggregation model is implemented in the fall3d volcanic ash transport model and applied to the 18 may 1980 mount st helens and the 17 18 september 1992 crater peak eruptions for both eruptions the optimized values for df 2 96 3 00 and e 0 27 0 33 indicate that the ash aggregates had a bulk density of 700 800 kg m 3 the model provides a higher degree of agreement than previous fully empirical aggregation models and successfully reproduces the depositional characteristics of the deposits investigated over a large range of scales including the position and thickness of the secondary maxima

quantifying volcanic ash dispersal and impact of the campanian ignimbrite super eruption 1 we apply a novel computational approach to assess for the first time volcanic ash dispersal during the campanian ignimbrite italy super eruption providing insights into eruption dynamics and the impact of this gigantic event the method uses a 3d time dependent computational ash dispersion model a set of wind fields and more than 100 thickness measurements of the ci tephra deposit results reveal that the ci eruption dispersed 250 300 km 3 of ash over 3 7 million km 2 the injection of such a large quantity of ash and volatiles into the atmosphere would have caused a volcanic winter during the heinrich event 4 the coldest and driest climatic episode of the last glacial period fluorine bearing leachate from the volcanic ash and acid rain would have further affected food sources and severely impacted late middle early upper paleolithic groups in southern and eastern europe citation costa a a folch g macedonio b giaccio r isaia and v c smith 2012 quantifying volcanic ash dispersal and impact of the campanian ignimbrite super eruption geophys res lett 39 l10310 doi 10 1029 2012gl051605

stratigraphic constraints for explosive activity in the past 100 ka at etna volcano italy the pyroclastic deposits of etna have been correlated over the whole volcanic edifice for the first time allowing the construction of a continuous record of tephra producing events which extends from approximately 100 ka to the present in this interval five main periods of explosive activity have been identified a 100 ka strombolian to subplinian activity b 80 to 100 ka plinian benmoreitic activity c 16 to 80 ka strombolian to subplinian from basaltic to mugearitic activity d 15 5 to 15 ka plinian benmoreitic activity accompanying the caldera forming eruptions of the ellittico volcano and e the most recent 13 ka basaltic explosive activity of strombolian and subplinian type of the present edifice that also includes the 122 b c plinian eruption this study results in a semi quantitative and in some cases quantitative definition of the intensity and chronology of the explosive activity at etna moreover this work gives a new significance to the volcanic hazards of etna a volcano generally considered to be the site of gentle effusive eruptions

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

the 1991 eruption of hekla iceland the eruption that started in the hekla volcano in south iceland on 17 january 1991 and came to an end on 11 march produced mainly andesitic lava this lava covers 23 km2 and has an estimated volume of 0 15 km3 this is the third eruption in only 20 years whereas the average repose period since 1104 is 55 years earthquakes as well as a strain pulse recorded by borehole strainmeters occurred less than half an hour before the start of the eruption the initial plinian phase was very short lived producing a total of only 0 02 km3 of tephra the eruption cloud attained 11 5 km in height in only 10 min but it became detached from the volcano a few hours later several fissures were active during the first day of the eruption including a part of the summit fissure by the second day however the activity was already essentially limited to that segment of the principal fissure where the main crater subsequently formed the average effusion rate during the first two days of the eruption was about 800 m3 s 1 after this peak the effusion rate declined rapidly to 10 20 m3 s 1 then more slowly to 1 m3 s 1 and remained at 1 12 m3 s 1 until the end of the eruption site observations near the main crater suggest that the intensity of the volcanic tremor varied directly with the force of the eruption a notable rise in the fluorine concentration of riverwater in the vicinity of the eruptive fissures occurred on the 5th day of the eruption but it levelled off on the 6th day and then remained essentially constant the volume and initial silica content of the lava and tephra the explosivity and effusion rate during the earliest stage of the eruption as well as the magnitude attained by the associated earthquakes support earlier suggestions that these parameters are positively related to the length of the preceeding repose period the chemical difference between the eruptive material of hekla itself and the lavas erupted in its vicinity can be explained in terms of a density stratified magma reservoir located at the bottom of the crust we propose that the shape of this reservoir its location at the west margin of a propagating rift and its association with a crustal weakness all contribute to the high eruption frequency of hekla

volcanic ash hazard in the central mediterranean assessed from geological data volcanic ash produced during explosive eruptions can have very severe impacts on modern technological societies here we use reconstructed patterns of fine ash dispersal recorded in terrestrial and marine geological archives to assess volcanic ash hazards the ash dispersal maps from nine holocene explosive eruptions of italian volcanoes have been used to construct frequency maps of distal ash deposition over a wide area which encompasses central and southern italy the adriatic and tyrrhenian seas and the balkans the maps are presented as two cumulative thickness isopach maps one for nine eruptions from different volcanoes and one for six eruptions from somma vesuvius these maps represent the first use of distal ash layers to construct volcanic hazard maps and the proposed methodology is easily applicable to other volcanic areas worldwide

nitrogen and 13c content of finsch and premier diamonds and their implications the nitrogen content and state of aggregation have been determined spectroscopically for diamonds from the finsch 93 and the premier 116 kimberlite south africa the ranges of concentration for diamonds with eclogitic e type and peridotitic p type mineral inclusions are finsch e type 29 to 1639 ppm p type 7 to 1206 ppm premier e type 15 to 1359 ppm p type 7 to 1086 ppm in both kimberlites nitrogen free diamonds type ii contain less frequently eclogitic inclusions among e type diamonds there are none of type ii in the finsch and 1 in the premier sample suite for p type diamonds the respective percentages are 29 and 25 there is no significant difference in the nitrogen aggregation state between e type and p type diamonds within each kimberlite however there is a significant difference between the two locations the nitrogen in the b form amounts to 26 29 n 65 in finsch and to 48 26 n 101 in premier diamonds no correlation between 13c and nitrogen content or aggregation state is observed however within the eclogitic and peridotitic paragenesis groups of diamonds of very similar nitrogen concentration 13c and mineral inclusion composition can be recognized one of these may be common to both kimberlites some of the diamonds in the two kimberlites may have had a common origin but subsequent thermal histories which differed for the sample suites from the two diatremes the nitrogen content of the diamonds is a function of local nitrogen concentration temperature and oxygen fugacity the dependence on the last of these can cause complex relationships between 15n 13c and nitrogen content of diamonds

feasibility of limestone reservoirs as a carbon dioxide storage site an experimental study carbon capture and storage technology is a means to permanently store carbon dioxide co2 in suitable geologic formations such as depleted oil and gas reservoirs and saline aquifers the potential of depleted carbonates reservoirs for being a secure storage site has been assessed in several studies based on the key storage aspects however minor attention has been given to rock type and the potential compaction of carbonates at different injection rates when geochemical interactions posed by supercritical co2 reduces their elastic properties and strength in this study limestone samples were tested to investigate changes in their physical and mechanical characteristics once flooded by co2 at a very low injection rate the results obtained indicate that an excessive pressure drop might be experienced even under a very low injection rate because of continuous dissolution of carbonates in the presence of co2 and brine creation of wormholes and the dissolution of the matrix were also observed through scanning electron microscope computerized tomography scan and nuclear magnetic resonance tests it was also observed that the elastic parameters and the strength of the limestone samples may significantly decrease after co2 flooding which might be linked to calcite dissolution and weakening of the solid skeleton

deep water gravity core from the marsili basin tyrrhenian sea records pleistocenic holocenic explosive events and instability of the aeolian archipelago italy abstract a 4 8 m long gravity core was recovered on a relative topographic high in the northern part of the marsili basin southern tyrrhenian sea at a water depth of 3200 m the core was taken in order to decipher the sedimentary record of the past volcanic events of the nearby aeolian arc a succession of thin 2 cm to 5 cm thick fine grained turbidites mainly of volcaniclastic origin topped by hemipelagic mud layers and a number of primary tephra layers were recovered by the core the most prominent turbidite occurs in the lower part of the core at 385 cm it consists of a 20 cm thick thinning upward pebble to sand sized bed grain size analysis and component compositions in the 0 063 0 250 mm size fractions were determined on thirty samples taken from primary tephra beds and the silty sandy basal part of the volcaniclastic turbidite units sem scans and glass fraction chemical analyses were successively carried out on a selection of 17 samples to aid source correlation and comparison sub aerial tephras of the lower pollara salina 24 3 6 ka gabellotto fiumebianco lipari 8 5 or 11 5 ka monte pilato lipari 749 or 580 ad and secche di lazzaro stromboli 5 ka eruptions were also analyzed with the same procedure primary tephra respectively belonging to the eruptions of lower pollara gabellotto fiumebianco and vesuvius ap eruptions 3 5 ka 79 ad were identified in the core at the expected relative stratigraphic depths two turbidite beds composed of monogenic glass shards were also identified and interpreted as the remobilisation of primary tephras of secche di lazzaro stromboli 5 ka and pilato lipari 580 or 749 ad tephrochronology results indicate that the cored sequence formed in the last 30 ka suggesting an average sedimentation rate of 0 15 0 17 mm y the thick pebbly sandy turbidite unit in the lower part of the core has component and glass composition compatible with the lower pollara volcanic sequence of salina island in view of the grain size and thickness of the turbidite unit we suggest that it represents the deposit of a large failure event the tephra corresponding to the lower pollara event lies below the turbidite unit separated by 16 cm of hemipelagic mud indicating that the collapse took place sometime after the eruption

the respiratory health hazards of volcanic ash a review for volcanic risk mitigation studies of the respiratory health effects of different types of volcanic ash have been undertaken only in the last 40 years and mostly since the eruption of mt st helens in 1980 this review of all published clinical epidemiological and toxicological studies and other work known to the authors up to and including 2005 highlights the sparseness of studies on acute health effects after eruptions and the complexity of evaluating the long term health risk silicosis non specific pneumoconiosis and chronic obstructive pulmonary disease in populations from prolonged exposure to ash due to persistent eruptive activity the acute and chronic health effects of volcanic ash depend upon particle size particularly the proportion of respirable sized material mineralogical composition including the crystalline silica content and the physico chemical properties of the surfaces of the ash particles all of which vary between volcanoes and even eruptions of the same volcano but adequate information on these key characteristics is not reported for most eruptions the incidence of acute respiratory symptoms e g asthma bronchitis varies greatly after ashfalls from very few if any reported cases to population outbreaks of asthma the studies are inadequate for excluding increases in acute respiratory mortality after eruptions individuals with pre existing lung disease including asthma can be at increased risk of their symptoms being exacerbated after falls of fine ash a comprehensive risk assessment including toxicological studies to determine the long term risk of silicosis from chronic exposure to volcanic ash has been undertaken only in the eruptions of mt st helens 1980 usa and soufriere hills montserrat 1995 onwards in the soufriere hills eruption a long term silicosis hazard has been identified and sufficient exposure and toxicological information obtained to make a probabilistic risk assessment for the development of silicosis in outdoor workers and the general population a more systematic approach to multi disciplinary studies in future eruptions is recommended including establishing an archive of ash samples and a website containing health advice for the public together with scientific and medical study guidelines for volcanologists and health care workers

central mediterranean explosive volcanism and tephrochronology during the last 630 ka based on the sediment record from lake ohrid abstract lake ohrid located in the central mediterranean region downwind of the italian volcanoes has great potential for developing a detailed record of the explosive activity of these volcanoes electron microprobe and laser ablation inductively coupled plasma mass spectrometry geochemical analyses of juvenile glass fragments of previously not analysed tephra layers of the deep site sediment record of lake ohrid expand the existing tephrostratigraphy for the interval marine isotope stages 1 16 the geochemical signatures of all tephra layers suggest an origin exclusively from the italian volcanism eight of these tephra layers have potential equivalents in marine and terrestrial archives of the central mediterranean region oh dp 1966 sc5 a7 oh dp 1955 ces1 a2 oh dp 1055 s1 oh dp 1006 s2 oh dp 0997 s3 oh dp 0710 s8 c 51 oh dp 0766 odp5 p 13 oh dp 0505 odp4 nine tephra layers which have not been described so far help to reconstruct the late volcanic activity of mount vulture oh dp 2439 and the paleovulsini oh dp 1998 the pre and post rio rava activity of the roccamonfina volcano oh dp 1911 1812 1733 1640 1527 the early activity of the aeolian arc oh dp 1513 1520 and the bracciano activity of the monti sabatini volcanic district oh dp 1175 the multi proxy dataset and chronology of the deep site sediments allowed definition of the climatostratigraphic position for all tephra layers and constrain the ages of so far unknown and or undated tephra layers the presented data provide a crucial increase of knowledge of the middle pleistocene tephrostratigraphy in the central mediterranean back to 630 ka and allows new insights of the volcanic activity of roccamonfina the roman province the campanian volcanic zone cvz the aeolian arc pantelleria and mount vulture