effects of scoria cone eruptions upon nearby human communities scoria cone eruptions are typically low in volume and explosivity compared with eruptions from stratovolcanoes but they can affect local populations profoundly scoria cone eruption effects vary dramatically due to eruption style tephra blanket extent climate types of land use the culture and complexity of the affected group and resulting governmental action a comparison of a historic eruption paricutin mexico with prehistoric eruptions herein we primarily focus on sunset crater in northern arizona usa elucidates the controls on and effects of these variables long term effects of lava flows extend little beyond the flow edges these flows however can be used for defensive purposes providing refuges from invasion for those who know them well in arid lands tephra blankets serve as mulches decreasing runoff and evaporation increasing infiltration and regulating soil temperature management and retention of these scoria mulches which can open new areas for agriculture become a priority for farming communities in humid areas though the tephra blanket may impede plant growth and increase erosion cultural responses to eruptions vary from cultural collapse through fragmentation of society dramatic changes and development of new technologies to little apparent change eruptions may also be viewed as retribution for poor behavior and attempts are made to mollify angry gods

tsunami hazard in the southeast aegean sea abstract we present a systematic assessment of the earthquake generated tsunami hazard for the greek island of rhodes in the se aegean sea our approach is based on numerical hydrodynamic simulations including inundation computations with most coupled with accurate bathymetry and topography data of the study area we have considered several hypothetical credible near field worst case scenarios and here we present results for four associated with seismic events of magnitude 8 0 to 8 4 our results include calculations of the maximum inundation the maximum wave elevation and the maximum flow depth in specific locales and assess the influence of the epicenter location on the tsunami hazard for time windows of 100 500 and 1000 years we illustrate our findings with lines superimposed on satellite images as maps indicating the estimated maximum values and in terms of two dimensional histograms given that our composite inundation for a 1000 year time period with our monte carlo variation of epicenters is overall larger than the inundation computed for existing well established worst case scenarios we caution the indiscriminate use of the latter in evaluating inundation in highly populated areas

the large late glacial ho eruption of the hudson volcano southern chile lakes formed in the aysen region of southern chile after the retreat of mountain glaciers established by 17 900 calendar years before present cal years bp or earlier contain numerous late glacial and holocene tephra layers derived from 70 eruptions of the volcanoes in the region including hudson the southernmost in the andean southern volcanic zone svz sediment cores from seven of these lakes contain an unusually thick late glacial age tephra layer which based on its distribution and bulk trace element composition was derived from a large explosive eruption of hudson volcano between 17 300 and 17 440 cal years bp and is termed ho in 13 cores from six of these lakes each located 100 km generally northeast of hudson the ho tephra layer ranges between 50 and 88 cm in thickness and contains pumice grains up to 2 cm in maximum diameter comparison with three previously documented large explosive holocene hudson eruptions h1 at 7 750 cal years bp h2 at 3 920 cal years bp and h3 in 1991 ad suggests that ho was larger with an estimated tephra volume of 20 km3 the largest post glacial eruption documented for any volcano in the southern andes and most likely responsible for the formation of the hudson caldera in total hudson has erupted 45 km3 of pyroclastic material in the last 17 500 years making it the most productive volcano in the southern andes in terms of the total volume erupted since the beginning of deglaciation in the region chemical stratification is not seen in the waterlain ho tephra but these deposits are bi modal consisting of a much greater proportion of dark glassy basaltic trachyandesite dense fragments and pumice with glasses which range between 55 and 59 wt sio2 along with volumetrically less significant lighter colored trachydacite pumice with glass of 66 wt sio2 in contrast h1 products are trachyandesitic in composition h2 ones are more felsic than h1 being composed essentially of trachydacite and although h3 1991 ad again produced tephra of bi modal compositions it erupted a much smaller proportion of mafic compared to felsic material than did ho thus the repetitive large explosive eruptions of hudson volcano have evolved to progressively less mafic overall compositions from late glacial to historic times and their volumes have decreased sr isotopic composition of bulk samples of the most mafic dense glass and most felsic pumice components of the ho tephra as well as samples from other hudson eruptions which overall range from 51 to 66 wt sio2 with 525 to 227 ppm sr are all similar 0 70444 0 00007 indicating that crystal liquid fractionation rather than crustal assimilation was the main process responsible for these chemical variations

chronological and geomorphological approach to the holocene tephras from tafi and santa maria valleys nw argentina fil sampietro vattuone maria marta universidad nacional de tucuman facultad de ciencias naturales e instituto miguel lillo laboratorio de geoarqueologia argentina consejo nacional de investigaciones cientificas y tecnicas argentina

tephra transformations variable preservation of tephra layers from two well studied eruptions volcanologists often use terrestrial tephra layers to reconstruct volcanic eruptions however the conversion of fresh tephra deposits into tephra layers is poorly understood to address this knowledge gap we surveyed tephra layers emplaced by the 1980 eruption of mount st helens usa msh1980 and the 1947 eruption of hekla iceland h1947 we compared our measurements with observations made shortly after the 1947 and 1980 eruptions to calibrate the subsequent transformation of the tephra deposit we expected the tephra layers to retain the broad characteristics of the original deposits but hypothesized a changes in thickness and mass loading due to re working and b positive correlations between thickness and vegetation density we observed some systematic changes in tephra layer properties with distance from the vent and the main plume axis however the preservation of the layers varied both between and within our survey locations closed coniferous forest appeared to provide good conditions for the preservation of the msh1980 tephra as expected preservation of the h1947 deposit in sparsely vegetated parts of iceland was much more variable however preservation of the msh1980 deposit in sparsely vegetated areas of eastern washington state was also excellent possibly due to biocrust formation we concluded that the preservation of tephra layers is sensitive to surface conditions at the time of the eruption these findings have implications for the reconstruction of past eruptions where eruption plumes span regions of variable surface cover

holocene explosive activity of hudson volcano southern andes fallout deposits in the vicinity of the southern andean hudson volcano record at least 12 explosive holocene eruptions including that of august 1991 which produced 4 km3 of pyroclastic material medial isopachs of compacted fallout deposits for two of the prehistoric hudson eruptions dated at approximately 3600 and 6700 bp enclose areas at least twice that of equivalent isopachs for both the 1991 hudson and the 1932 quizapu eruptions the two largest in the andes this century however lack of information for either the proximal or distal tephra deposits from these two prehistoric eruptions of hudson precludes accurate volume estimates andesitic pyroclastic material produced by the 6700 bp event including a 1 10 cm thick layer of compacted tephra that constitutes a secondary thickness maximum over 900 km to the south in tierra del fuego was dispersed in a more southerly direction than that of the 1991 hudson eruption the products of the 6700 bp event consist of a large proportion of fine pumiceous ash and accretionary lapilli indicating a violent phreatomagmatic eruption this eruption which is considered to be the largest for hudson and possibly for any volcano in the southern andes during the holocene may have created hudson s 10 km diameter summit caldera but the age of the caldera has not been dated independently

local and regional scale impacts of the 74 ka toba supervolcanic eruption on hominin populations and habitats in india abstract the toba supervolcanic eruption of 74 000 years ago is argued to have devastated homo sapiens populations causing a human population bottleneck through a combination of rapid global climatic deterioration and ecological disruption following the widespread ash fall this dramatic eruption the largest in at least the last 2 million years is hypothesized to have shaped the genetic structure and diversity of human populations today past assessments of toba s human impacts however have been predominantly theoretical using archaeological and geological evidence from sites in india this study addresses toba s local scale impacts on hominin technology behavior demography and habitats in two valleys in india the jurreru and middle son valleys using paleoclimatological and volcanological data regional scale impacts throughout india are inferred a refugia hypothesis is presented that argues for variation in the scale of toba s impact throughout india driven by regional differences in monsoonal dynamics geography and topography areas of north west india the indo gangetic plain and parts of the deccan to the east of the western ghats are argued to have been the most affected whereas areas of southern and eastern india may have preserved the largest refugia for hominin populations

residents attitudes and behaviour before and after the 2010 eyjafjallajokull eruptions a case study from southern iceland while the disruption to international air travel caused by the eruption of iceland s eyjafjallajokull volcano in 2010 has been well documented the significant social impacts on local residents from ash fall to the south and east of the crater are less well known these impacts and attitudes of impacted residents and emergency managers are the foci of our present study prior to and during the eruption officials worked to protect the local population from the glacial outburst floods jokulhlaup that were of primary concern the success of these endeavours can in part be attributed to a regional evacuation exercise held in march 2006 an exercise that was carried out with respect to a possible eruption at another volcano katla that is located 25 km to the east of eyjafjallajokull eruptions at either volcano will impact the same communities our study here concentrates on alftaver a small farming community located approximately 60 km east southeast of eyjafjallajokull and 30 km southeast of katla alftaver has been the subject of longitudinal studies carried out in 2004 2006 and 2008 these studies highlighted the difficulties that emergency managers face in developing appropriate response strategies acceptable to vulnerable communities the 2010 eyjafjallajokull eruptions presented an opportunity to re assess residents attitudes and behaviour in relation to volcanic risk management in the wake of their first hand experiences with volcanic hazards to achieve this interviews were conducted with residents and emergency management officials and a questionnaire was distributed to residents this paper presents the results of this survey and examines changes in attitudes towards volcanic risk management it was apparent that the experience of ash fall from eyjafjallajokull provided a better perspective of what could be expected from a katla eruption and that attitudes towards emergency management had evolved accordingly importantly officials perceptions of risk are now more aligned with those of residents and both recognise the need for more detailed and concise information regarding the impacts of ash fall during and following volcanic eruptions

refining the late quaternary tephrochronology for southern south america using the laguna potrok aike sedimentary record abstract this paper presents a detailed record of volcanism extending back to 80 kyr bp for southern south america using the sediments of laguna potrok aike icdp expedition 5022 potrok aike maar lake sediment archive drilling project pasado our analysis of tephra includes the morphology of glass the mineral componentry the abundance of glass shards lithics and minerals and the composition of glass shards in relation to the stratigraphy firstly a reference database of glass compositions of known eruptions in the region was created to enable robust tephra correlations this includes data published elsewhere in addition to new glass shard analyses of proximal tephra deposits from hudson eruption units h 1 and h 2 aguilera a 1 reclus r 1 r 2 3 mt burney mb 1 mb 2 mb x mb 1910 and historical lautaro viedma deposits the analysis of the ninety four tephra layers observed in the laguna potrok aike sedimentary sequence reveals that twenty five tephra deposits in the record are the result of primary fallout and are sourced from at least three different volcanoes in the austral andean volcanic zone mt burney reclus lautaro viedma and one in the southernmost southern volcanic zone hudson one new correlation to the widespread h 1 eruption from hudson volcano at 8 7 8 6 9 0 cal ka bp during the quaternary is identified the identification of sixty five discrete deposits that were predominantly volcanic ashes glass and minerals with subtle characteristics of reworking in addition to three likely reworked tephra and one unknown layer indicates that care must be taken in the analysis of both visible and invisible tephra layers to decipher their emplacement mechanisms

ash storms impacts of wind remobilised volcanic ash on rural communities and agriculture following the 1991 hudson eruption southern patagonia chile tephra fall from the august 1991 eruption of volcan hudson affected some 100 000 km 2 of patagonia and was almost immediately reworked by strong winds creating billowing clouds of remobilised ash or ash storms the immediate impacts on agriculture and rural communities were severe but were then greatly exacerbated by continuing ash storms this paper describes the findings of a 3 week study tour of the diverse environments of southern patagonia affected by ash storms with an emphasis on determining the impacts of repeated ash storms on agriculture and local practices that were developed in an attempt to mitigate these impacts ash storms produce similar effects to initial tephra eruptions prolonged for considerable periods these have included the burial of farmland under dune deposits abrasion of vegetation and contamination of feed supplies with fine ash these impacts can then cause problems for grazing animals such as starvation severe tooth abrasion gastrointestinal problems corneal abrasion and blindness and exhaustion if sheep fleeces become laden with ash in addition ash storms have led to exacerbated soil erosion human health impacts increased cleanup requirements sedimentation in irrigation canals and disruption of aviation and land transport ash deposits were naturally stabilised most rapidly in areas with high rainfall 1 500 mm year through compaction and enhanced vegetation growth stabilisation was slowest in windy semi arid regions destruction of vegetation and

a new evaluation of palaeo heat flows and eroded thicknesses for the carboniferous ruhr basin western germany palaeo heat flows and thicknesses of eroded carboniferous overburden in the coal bearing ruhr basin western germany were estimated using one dimensional basin modelling techniques thermal and burial histories for 11 localities were calibrated by comparing measured and calculated vitrinite reflectance data based on the assumption of pre tectonic maturation in contrast to former studies the kinetic easy r0 approach applied for the calculation of vitrinite reflectance lopatin s tti algorithm was used in addition for one well in order to demonstrate the impact of the selection of the algorithm for vitrinite reflectance calculation on the simulation results simulated palaeo heat flows for the time of maximum burial most probably in the stephanian range from 64 to 83 mw m2 and decrease towards the south these heat flows are lower than values computed during earlier studies but are still relatively high in comparison to recent foreland basins the regional distribution of palaeo heat flows indicates that the crust beneath the ruhr basin was relatively thin and thickened towards the south at the end of the carboniferous after the stephanian 2200 3500 m of carboniferous overburden were eroded an observed southward increase in eroded thicknesses is caused by an uplift of the area studied which decreased towards the north at the end of the variscan folding large thicknesses of deposited and later eroded carboniferous sediments have to be postulated to explain the maturity data even along the present southern margin of the ruhr basin this indicates that the late carboniferous sediments originally extended far to the south geological arguments suggest that the deposition of carboniferous sediments in the entire ruhr basin continued until the stephanian

sources of dissolved silica to the fjords of northern patagonia 44 48 s the importance of volcanic ash soil distribution and weathering dissolved silica dsi plays an important biogeochemical role in the fjords of northern chilean patagonia 44 48 s where it drives high biogenic productivity and promotes carbon burial it is generally believed that the dsi riverine input to lakes and coastal environments is controlled by a combination of factors including lithology climate topography vegetation and meltwater input in northern chilean patagonia several authors have proposed that the postglacial volcanic ash soils andosols may play a significant role in the high supply of dsi to the regional fjords to assess the influence of andosols on dsi concentrations in north patagonian rivers we mapped andosol thickness and compared our results with river chemistry the mineralogical and geochemical composition of three representative andosol profiles was also examined to evaluate the efficiency of weathering processes the andosol thickness map clearly demonstrates that volcanic ash was predominantly deposited on the eastern side of the regional volcanoes reflecting the influence of the prevailing westerly winds on the distribution of pyroclastic material mineralogical and geochemical results show that the andosol parent material has the typical andesitic basaltic signature of the regional volcanoes i e high amounts of amorphous material plagioclase k feldspar and pyroxene down profile variations in soil mineralogy and geochemistry indicate increased leaching of silica with depth resulting from weathering of the volcanic parent material for the five studied watersheds a highly positive correlation r2 0 98 was found between average andosol thickness and dsi concentrations suggesting that andosol thickness is the main parameter affecting dsi concentrations in north patagonian river systems on seasonal timescales increased precipitation winter and glacial meltwater summer input can significantly reduce dsi concentrations we argue that the weathering of andosols constitutes the most important source of dsi to the lakes and fjords of northern chilean patagonia explaining the particularly high regional rates of biogenic silica production copyright 2015 john wiley sons ltd

a 7000 year high resolution lake sediment record from coastal central chile lago vichuquen 34 s implications for past sea level and environmental variability we present a 7 ka environmental reconstruction based on sedimentological and geochemical data from lago vichuquen a coastal eutrophic lake in central chile 34 48 s 72 03 w 4 m a s l a relatively shallow and restricted marine environment with low productivity high detrital input and dominant anoxic conditions in the vichuquen basin occurred from 7 0 to 6 5 cal ka bp rapid onset of a holocene marine transgression at 6 5 cal ka bp favoured deeper and more biologically productive environments that existed until 2 8 cal ka bp bioproductivity changes during the mid holocene 6 5 4 2 cal ka bp were related to upwelling dynamics controlled by the intensity of the south east pacific anticyclone spa periods with lower organic productivity and dominant anoxic conditions reflect an increased intensity of spa increased upwelling and decreased precipitation a shift at 4 0 cal ka bp reflects the onset of modern southern westerly winds and el nino southern oscillation patterns tectonic uplifting and geormorphological activity dune advancement are possible reasons behind the vichuquen basin closure at 1 2 cal ka bp leading to a low bioproductivity lacustrine environment which has developed until the present

modeling the resuspension of ash deposited during the eruption of eyjafjallajokull in spring 2010 1 eyjafjallajokull a volcano in southern iceland erupted explosively in april and may 2010 depositing ash over a region of more than 3000 km2 to the east and southeast of the volcano this deposited ash has been frequently remobilized by the wind causing concern for the health of icelanders living in the region an investigation was carried out to determine whether it would be possible to produce forecasts of days when high airborne ash concentrations were likely to occur information about the spatially varying surface characteristics of the region of deposited ash is not available so in the modeling approach adopted here ash is released from the surface at a rate proportional to the cube of the excess friction velocity local friction velocity minus a threshold only when the friction velocity exceeds a threshold movement of the resuspended ash is then modeled in a lagrangian dispersion model modeled ash concentrations are compared to observed concentrations from two periods pm10 observations between 23 may and 2 july 2010 and airborne particle counts between 21 september 2010 and 16 february 2011 more than 66 of the resuspension episodes between may and july are captured by the model and the relative magnitudes of the modeled episodes in this period are in good agreement with the observations 66 of episodes between october and february are also captured by the model although there is an increase in the false alarm rate which appears to be due to the influence of precipitation

sedimentological analysis of the tephra from the 12 15 august 1991 eruption of hudson volcano the tephra fallout from the 12 15 august 1991 explosive eruption of hudson volcano cordillera de los andes 45 54 s 72 58 w chile was dispersed on a narrow elongated ese sector of patagonia covering an area on land of more than 100 000 km2 the elongated shape of the deposit together with the relatively coarse mean and median values of the particles at a considerable distance from the vent were the result of strong winds blowing to the southeast during the eruption the thickness of the fall deposit decreases up to 250 km ese from hudson volcano where it begins to thicken again secondary maxima are well developed at approximately 500 km from the vent secondary maxima together with grainsize bimodality in individual layers and in the bulk deposit suggest that particle aggregation played an important role in tephra sedimentation the fallout deposit is well stratified with alternating fine grained and coarsegrained layers which is probably a result of strong eruptive pulses followed by relatively calm periods and or changes in the eruptive style from plinian to phreatoplinian the tephra is mostly composed of juvenile material the coarse mode mostly pumice shifts to finer sizes with distance from the volcano the fine mode mostly glass shards is always about 5 6 phi glass shards and pumice are mostly light gray to colorless however considerable amounts of dark poorly vesiculated blocky shards suggest a hydromagmatic component in the eruption a land based tephra volume of 4 35 km3 was estimated and a total volume of 7 6 km3 arose from an extrapolation which took into account the probable volume sedimented in the sea bulk density ranges from 0 9 to 1 10 gr cm3 beyond 110 km from the vent rather uniform density values measured in crushed samples 2 45 2 50 gr cm3 at all distances from the vent reveal a relatively homogeneous composition mean and median sizes decrease rapidly up to 270 km from the vent beyond that point they are more or less constant whereas the maximum size 1 phi shows a steady decrease up to 550 km a concomitant improvement in sorting is observed this is attributed to sorting due to wind transport combined with particle aggregation at different times and distances from the vent the hudson tephra fallout shares some strikingly similar features with the mount st helens 18 may 1980 and quizapu 1932 eruptions

changes in mid and far field human landscape use following the laacher see eruption c 13 000 bp abstract around 13 000 years ago the laacher see volcano east eifel volcanic field rhenish shield erupted cataclysmically the thick tephra blanket in the eruption s near field covered and thereby preserved a large number of archaeological sites ranging from very small to some of the largest and richest sites known from the late glacial in this proximal region there is a striking contrast in the number of sites prior to the eruption and the almost complete lack of sites dating to the period after the event i e to greenland interstadial 1a the preservative function of the tephra cover itself may explain this near field pattern but it is shown here that similar stratigraphic observations can also be made in the laacher see eruption s mid field towards the west and in particular to the north east the aim of this paper is to review the stratigraphic relations of known archaeological sites outside the near field of the laacher see event with a particular focus on the german federal state of hesse and adjacent areas of lower saxony and the thuringian basin here a number of archaeological sites are known where strata of laacher see tephra cap human occupation most often these sites are not reoccupied until much later in prehistory suggesting that the eruption may have led either to a complete or a near complete abandonment of the affected regions or at the very least to a major reorganisation of landscape use

environmental assessment of 1991 hudson volcano eruption ashfall effects on southern patagonia region argentina the august 1991 eruption of the hudson volcano in the southern andean volcanic zone affected an area of 1000 km in radius to the east in the argentine patagonic meseta the thickness of ash ranged from 20 cm in the andean area to less than 1 mm in the atlantic coast zone wind storms reactivated the ash deposits together with terrigenous material more than one year after the eruption in order to assess the potential risk of the ash analyses of concentration size mineralogical composition toxic elements and irritating effects of gases were performed in all samples the percentage of particles of the 2 to 5 m range is below the toxic threshold level trace elements are below the toxic threshold concentration for humans and animals the major impact of the ashfall was on sheep herds about one third of them were lost in the areas close to the volcano soil incorporated the ash layers and a fast recovery of orchards was reported two years later rivers were loaded with sediment in the immediate aftermath but one year later returned to previous conditions along the shores of the buenos aires lake a fresh tephra layer can be distinguished

ash mists and brown snow remobilization of volcanic ash from recent icelandic eruptions recent eruptions in iceland and chile have demonstrated that volcanic ash problems persist long after an eruption for this reason ash dispersion models are being extended to include ash remobilization critical to these models is knowledge of the ash source and the particle sizes that can be mobilized under different wind and moisture conditions here we characterize the physical and chemical characteristics of ash deposited on new snow in reykjavik iceland following a blizzard on 6 march 2013 morphological textural and compositional analyses indicate resuspension from multiple eruptive deposits including both grimsvotn 2011 and eyjafjallajokull 2010 eruptions grain size measurements show a mode of 32 63 m with particles as large as 177 m there is little mass in the very fine fraction 10 m pm10 we compare our observations to predictions using the lagrangian particle dispersion model name uk met office the model output is consistent with observations in that it forecasts resuspension from both eyjafjallajokull and grimsvotn source regions and shows ash deposition coincident with the timing of observed deposition in reykjavik the modeled deposit in reykjavik predicts however a substantially lower proportion of grimsvotn ash than observed this discrepancy has highlighted the need to reassess the assumptions used in the simulations particularly regarding the source area and precipitation thresholds furthermore we suggest that modification of ash deposits in the form of erosion redeposition compaction or cementation may influence the dynamics of resuspension over time thus influencing the ability of model simulations to accurately forecast remobilization events

sedimentation of long lasting wind affected volcanic plumes the example of the 2011 rhyolitic cordon caulle eruption chile sedimentation processes and fragmentation mechanisms during explosive volcanic eruptions can be constrained based on detailed analysis of grain size variations of tephra deposits with distance from vent and total grain size distribution tgsd grain size studies strongly rely on deposit exposure and in case of long lasting eruptions can be complicated by the intricate interplay between eruptive style atmospheric conditions particle accumulation and deposit erosion the 2011 cordon caulle eruption chile represents an ideals laboratory for the study of long lasting eruptions thanks to the good deposit accessibility in medial to distal area all layers analyzed are mostly characterized by bimodal grain size distributions with both the modes and the fraction of the coarse subpopulation decreasing rapidly with distance from vent and those of the fine subpopulation being mostly stable due to gradually changing wind direction the two subpopulations characterizing the deposit of the first 2 days of the eruption are asymmetrically distributed with respect to the dispersal axis the tgsd of the climactic phase is also bimodal with the coarse subpopulation representing 90 wt of the whole distribution polymodality of individual samples is related to size selective sedimentation processes while polymodality of the tgsd is mostly related to the complex internal texture e g size and shape of vesicles of the most abundant juvenile clasts the most representative tgsd could be derived based on a combination of the voronoi tessellation with a detailed analysis of the thinning trend of individual size categories finally preferential breakage of coarse pumices on ground impact was inferred from the study of particle terminal velocity

late quaternary tephrostratigraphy of southern chile and argentina abstract the southern and austral volcanic zones of the andes comprise 74 volcanic centres with known post glacial activity at least 21 of these have had one or more large explosive eruptions in the late quaternary dispersing tephra over vast areas these tephra layers therefore have great potential as tephrochronological marker horizons in palaeoenvironmental studies in southern chile and argentina a region that is particularly useful to study climate dynamics of the southern hemisphere however to date tephrochronology has rarely been fully utilised in this region as a correlation and dating tool here we review the existing post glacial tephrostratigraphic record of the southern and austral volcanic zones and compile a database of known occurrences of tephra from these volcanoes in ice and lacustrine marine peat and cave sediment records we address the inconsistencies in and revisions of the tephrostratigraphies presented in prior literature and discuss the challenges in correlating tephras and the limitations of the tephrostratigraphic record in this area this study highlights the many gaps that still exist in our knowledge of the eruptive histories of these volcanoes but also reveals the largely under utilised potential of tephra as a correlation tool in this region this is exemplified by the severe lack of adequate geochemical analysis of tephra layers preserved in many lacustrine and peat sediment sections which are particularly important tephrostratigraphic records in southern chile and argentina due to the paucity of surface preservation

potential impacts of tephra fallout from a large scale explosive eruption at sakurajima volcano japan we present an exposure analysis of infrastructure and lifeline to tephra fallout for a future large scale explosive eruption of sakurajima volcano an eruption scenario is identified based on the field characterization of the last subplinian eruption at sakurajima and a review of reports of the eruptions that occurred in the past six centuries a scenario based probabilistic hazard assessment is performed using the tephra2 model considering various eruption durations to reflect complex eruptive sequences of all considered reference eruptions a quantitative exposure analysis of infrastructures and lifelines is presented primarily using open access data the post event impact assessment of magill et al earth planets space 65 677 698 2013 after the 2011 vei 2 eruption of shinmoedake is used to discuss the vulnerability and the resilience of infrastructures during a future large eruption of sakurajima results indicate a main eastward dispersal with longer eruption durations increasing the probability of tephra accumulation in proximal areas and reducing it in distal areas the exposure analysis reveals that 2300 km of road network 18 km2 of urban area and 306 km2 of agricultural land have a 50 probability of being affected by an accumulation of tephra of 1 kg m2 a simple qualitative exposure analysis suggests that the municipalities of kagoshima kanoya and tarumizu are the most likely to suffer impacts finally the 2011 vei 2 eruption of shinmoedake demonstrated that the already implemented mitigation strategies have increased resilience and improved recovery of affected infrastructures nevertheless the extent to which these mitigation actions will perform during the vei 4 eruption presented here is unclear and our hazard assessment points to possible damages on the sakurajima peninsula and the neighboring municipality of tarumizu

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

resuspension of ash after the 2014 phreatic eruption at ontake volcano japan abstract we determined the resuspension process of an ash deposit after the phreatic eruption of september 27th 2014 at ontake volcano japan by analyzing the time series data of particle concentrations obtained using an optical particle counter and the characteristics of an ash sample the time series of particle concentration was obtained by an optical particle counter installed 11 km from the volcano from september 21st to october 19th 2014 the time series contains counts of dust particles ash and soil pollen and water drops and was corrected to calculate the concentration of dust particles based on a polarization factor reflecting the optical anisotropy of particles the dust concentration was compared with the time series of wind velocity the dust concentration was high and the correlation coefficient with wind velocity was positive from september 28th to october 2nd grain size analysis of an ash sample confirmed that the ash deposit contains abundant very fine particles

how does tephra deposit thickness change over time a calibration exercise based on the 1980 mount st helens tephra deposit abstract tephra layers are frequently used to reconstruct past volcanic activity inferences made from tephra layers rely on the assumption that the preserved tephra layer is representative of the initial deposit however a great deal can happen to tephra after it is deposited thus tephra layer taphonomy is a crucial but poorly understood process the overall goal of this research was to gain greater insight into the taphonomy of terrestrial tephra layers specifically the extent to which deposit thickness is altered over time with implications for tephra volume estimation we approached this by a conducting a new survey of the tephra layer from the recent well studied eruption of mount st helens on may 18th 1980 msh1980 b modelling the tephra layer thickness using a mathematical technique and c comparing our results with an equivalent model based on measurements taken immediately after the eruption in this way we aimed to quantify any losses and transformations that have occurred during our study we collected measurements of tephra layer thickness from 86 locations ranging from 600 km from the vent geochemical analysis was used to identify tephra of uncertain origin our results indicated that the extant tephra layer at undisturbed sites was representative of the original deposit overall preservation in these locations in terms of thickness stratigraphy and geochemistry had been remarkably good however the isopach maps generated from our measurements diverged from isopachs produced in the same way but derived from the original survey data furthermore our estimates of the quantity of tephra produced during the eruption greatly exceeded previous estimates of the fallout volume in our study inaccuracies in the modelled fallout arose from issues of sampling strategy rather than taphonomy our results demonstrate the sensitivity of volcanological reconstructions to measurement location and the great importance of reliably measured low zero values in reconstructing tephra deposits

the immediate environmental effects of tephra emission the earth s history is punctuated by large explosive eruptions that eject large quantities of magma and silicate rock fragments into the atmosphere these tephra particles can sometimes be dispersed across millions of square kilometres or even entire continents the interaction of tephra with or in receiving environments may induce an array of physical chemical and biological effects the consequences for affected systems and any dependent communities may be chronic and localised in the event of frequent small eruptions while larger and rarer events may have acute regional scale impacts it is therefore necessary to document the range of possible impacts that tephra may induce in receiving environments and any resulting effects in interconnected systems we collate results from many studies to offer a detailed multidisciplinary and interdisciplinary review of the immediate post eruptive effects of tephra emission into the atmosphere onto vegetation soil or ice snow surfaces and in aquatic systems we further consider the repercussions that may be induced in the weeks to years afterwards in the atmosphere tephra can influence cloud properties and air chemistry by acting as ice nuclei in or by offering sites for heterogeneous reactions respectively tephra on vegetation causes physical damage and sustained coverage may elicit longer term physiological responses tephra deposits on soils may alter their capacity to exchange gas water and heat with the atmosphere or may have a specific chemical effect such as nutrient input or acidification on sensitive soils tephra deposition onto snow or ice may affect ablation rates rivers and lakes may experience turbidity increases and changes in their morphology as a result of fallout and prolonged months or years erosion from the tephra covered catchment in the first weeks after deposition tephra leaching may affect river chemistry the abundance and speciation of phytoplankton populations in lakes may be altered by tephra induced changes in water chemistry or sediment water nutrient cycling in the oceans tephra deposition may fertilise fe limited waters with potential impacts on the global carbon cycle embracing the full complexity of environmental effects caused by tephra fall demands a renewed investigative effort drawing on interdisciplinary field and laboratory studies combined with consideration of the interconnectivity of induced impacts within and between different receiving environments

sources of uncertainty in the mazama isopachs and the implications for interpreting distal tephra deposits from large magnitude eruptions estimating the area of tephra fallout and volume of large magnitude eruptions is fundamental to interpretations of the hazards posed by eruptions of this scale this study uses the tephra from the caldera forming eruption of mount mazama crater lake or usa to demonstrate the challenges faced when working with large prehistoric tephra deposits and outlines the methodologies required to determine eruption volume and magnitude we combine 250 mazama tephra occurrences reported by a range of disciplines including archaeology paleoclimatology and volcanology with new field studies to better understand the extent of the distal tephra we find that the mazama tephra has been remobilised to varying degrees over the past 7000 years so each tephra locality was appraised for the likelihood that it records primary tephra fallout we designated 45 of the distal 100 km from source tephra sites as suitable for use in the production of isopachs using a spline fitting method the new distal isopachs were then integrated with proximal fallout data and estimates of the ignimbrite volume from previous studies to revise the estimated bulk erupted volume from the climactic mazama eruption to 176 km3 61 km3 dense rock equivalent dre this study demonstrates the importance of collating tephra localities from a range of disciplines and that even remobilised deposits provide valuable information about the extent of the deposit interpreting remobilised deposits can provide insight into post eruptive processes that could potentially pose secondary hazards following large magnitude eruptions we also show that in some circumstances remobilised deposits preserve important physical properties such as grain size

compositional variations and magma mixing in the 1991 eruptions of hudson volcano chile the august 1991 eruptions of hudson volcano produced 2 7 km3 dense rock equivalent dre of basaltic to trachyandesitic pyroclastic deposits making it one of the largest historical eruptions in south america phase 1 of the eruption p1 april 8 involved both lava flows and a phreatomagmatic eruption from a fissure located in the nw corner of the caldera the paroxysmal phase p2 began several days later april 12 with a plinian style eruption from a different vent 4 km to the south southeast tephra from the 1991 eruption ranges in composition from basalt phase 1 to trachyandesite phase 2 with a distinct gap between the two erupted phases from 54 60 wt sio2 a trend of decreasing sio2 is evident from the earliest part of the phase 2 eruption unit a 63 65 wt sio2 to the end unit d 60 63 wt sio2 melt inclusion data and textures suggest that mixing occurred in magmas from both eruptive phases the basaltic and trachyandesitic magmas can be genetically related through both magma mixing and fractional crystallization processes a combination of observed phase assemblages inferred water content crystallinity and geothermometry estimates suggest pre eruptive storage of the phase 2 trachyandesite at pressures between 50 100 megapascal mpa at 972 26 c under water saturated conditions log fo2 10 33 0 2 it is proposed that rising p1 basaltic magma intersected the lower part of the p2 magma storage region between 2 and 3 km depth subsequent mixing between the two magmas preferentially hybridized the lower part of the chamber basaltic magma continued advancing towards the surface as a dyke to eventually be erupted in the northwestern part of the hudson caldera the presence of tachylite in the p1 products suggests that some of the magma was stalled close to the surface 0 5 km prior to eruption seismicity related to magma movement and the p1 eruption combined with chamber overpressure associated with basalt injection may have created a pathway to the surface for the trachyandesite magma and subsequent p2 eruption at a different vent 4 km to the south southeast

delayed sedimentary response to the a d 1886 eruption of tarawera new zealand sedimentary response to tephra deposition from substantial volcanic eruptions is generally immediate and dramatic an important exception is the a d 1886 eruption of mount tarawera new zealand which blanketed 200 km 2 with 50 cm of basaltic scoria and ash fall erupted from a fissure through the tarawera dome complex this fall deposit has suffered very little rilling or other surface erosion and there was no immediate downstream redistribution of tephra by lahars or dilute floods we attribute this lack of early response to the high permeability of the tephra deposit and gentle relief in the areas of substantial accumulation numerous small lakes occur among the dome complexes of okataina caldera and one direct result of the eruption was constriction of lake tarawera9s outflow which caused the lake to rise substantially eighteen years after the eruption collapse of a tephra bank that had controlled lake level triggered a breakout flood from this raised intracaldera lake triggering a decades long period of intense tributary erosion in the upper catchment and damaging stream bed aggradation outside the caldera this abrupt increase in sediment yield from an initially stable posteruptive landscape has no documented precedents yet may be a common posteruptive sedimentary response in caldera complexes of temperate to humid regions

stratigraphy age and correlation of lepue tephra a widespread c 11 000 cal a bp marker horizon sourced from the chaiten sector of southern chile we describe the stratigraphy age and correlation of a prominent tephra marker named lepue tephra extensively distributed in north western patagonia lepue tephra is well dated at c 11 000 cal a bp from numerous lake and soil cover bed sequences and its recognition is useful for assessing the rate and timing of deglaciation as well as associated environmental changes in this region during the last glacial termination and early holocene lepue tephra has attributes typical of a complex and compositionally zoned phreatomagmatic eruptive while the initial rhyolitic phase can be readily distinguished from multiple eruptive products sourced from the adjacent volcan chaiten the main erupted end member is of basaltic andesitic bulk composition similar to younger tephras sourced from holocene monogenetic cones adjacent to the volcan michimahuida massif tmim lepue tephra can be correlated to an equivalent aged pyroclastic flow deposit amarillo ignimbrite prominently distributed in the south eastern sector of tmim the source vent for these co eruptive events is obscured by an extensive ice field and is currently unknown the widespread radially symmetrical distribution of lepue tephra centred on tmim cannot be attributed solely to volcanological considerations reduced southern hemisphere westerly wind influence interpreted from climate proxies at the time of eruption are also implicated

ash resuspension related to the 2011 2012 cordon caulle eruption chile in a rural community of patagonia argentina abstract the 2011 2012 cordon caulle eruption emitted about 1 km3 of rhyodacitic tephra dominant westerly winds in the region caused most of the primary tephra to deposit in neighboring argentina in addition to the impact of widespread dispersal and fallout of primary tephra during the eruption argentina was also significantly affected by remobilization of the primary ash even several years after the climactic phase of the eruption in this mixed methods study we combine aspects of natural and social sciences to characterize the ash resuspension events associated with the 2011 2012 cordon caulle deposits and assess the impacts on the argentinian farming community of ingeniero jacobacci in the patagonian steppe our findings show the primary importance of wind rainfall and ash availability in controlling the occurrence and persistence of ash resuspension events the role played by these variables was also reflected in the seasonal distribution of events observed regarding the impacts our results complement those of earlier studies and demonstrate that ash resuspension events can exacerbate the negative impact of primary tephra fallout events from the time of deposition to many years after the eruption only after five years has the environment and the farming community begun to show signs of recovery our findings also highlight the importance of assessing ash resuspension events in multi hazard scenarios involving volcanic and hydrometeorologic hazards

past human populations and landscapes in the fuegian archipelago southernmost south america this contribution discusses possible relationships between human populations and holocene environmental deterioration phenomena cold arid pulses and volcanic eruptions in the fuegian archipelago south america based on summed probability distributions of archaeological dates paleoenvironmental information geospatial data and archaeological evidence during the first millennia after peopling only the hudson ca 7700 cal yr bp and the first monte burney ca 8600 cal yr bp eruptions might have played a role in human dispersion particularly a more intense human occupation around the beagle channel and long distance interactions are proposed as risk buffer strategies related to the hudson eruption a cooling phase and a demographic growth at ca 5500 cal yr bp might have favored more dispersed spatial occupations and a subsistence diversification in the beagle channel in the northern steppes the second monte burney eruption ca 4300 cal yr bp and an arid episode ca 2600 cal yr bp are proposed as the main triggers for changes in land use patterns long network interactions and subsistence strategies even though occupation changes in the fuegian archipelago coexist with environmental deterioration episodes after 1500 cal yr bp demographic processes and the european colonization most likely explain this trend similarities between the steppe ecotone and forest occupation curves suggest common behavioral patterns across the holocene

fate and agricultural consequences of leachable elements added to the environment from the 2011 cordon caulle tephra fall abstract the june 2011 eruption of cordon caulle volcano chile dispersed tephra over 350 000 km 2 including productive agricultural land this resulted in the death of nearly one million livestock two distinct environments were affected a proximal temperate andean setting and the semi arid argentine steppe farther from the volcano the purpose of this study was to better understand the fate and agricultural consequences of leachable elements added to the environment by this large silicic tephra fall tephra soil and surface water samples across the depositional area were collected both immediately after the eruption tephra and water and nine months afterwards tephra soil and water tephra samples were analysed following a new hazard assessment protocol developed by the international volcanic health hazard network ivhhn water extractable element concentrations in freshly collected tephra were very low to low compared to other eruptions and showed no trends with distance from the volcano surface water analyses suggested short term changes to water composition due to the release of elements from tephra no effect on the fertility of soils underlying tephra was apparent after nine months water extractable fluorine f in freshly collected tephra ranged from 12 to 167 mg kg with a median value of 67 mg kg based on parallels with the 11 12 october 1995 eruption of ruapehu volcano new zealand we conclude that f toxicity was a possible contributing factor to the large scale livestock deaths as well as to chronic fluorosis widely reported in wild deer populations across the cordon caulle tephra depositional area finally we recommend that effective response to widespread tephra fall over agricultural areas should include 1 rapid statistically representative field sampling of tephra soils surface water supplies and forage crops 2 analysis using appropriate and reliable laboratory methods 3 modelling both short and long term impacts on the ecosystem especially for elements that may generate chronic hazard 4 timely dissemination of results to agricultural agencies 5 longitudinal sampling and monitoring to adapt impact models and 6 developing reliable animal fatality diagnoses through autopsies and chemical analysis

material sources chemical weathering and physical denudation in the chubut river basin patagonia argentina implications for andean rivers abstract the chubut is a medium size 42 000 km2 river basin that drains the arid to semiarid patagonian seaboard and pours its waters into the southwestern atlantic ocean ca lat 43 20 documentclass aastex usepackage amsbsy usepackage amsfonts usepackage amssymb usepackage bm usepackage mathrsfs usepackage pifont usepackage stmaryrd usepackage textcomp usepackage portland xspace usepackage amsmath amsxtra usepackage ot2 ot1 fontenc newcommand cyr renewcommand rmdefault wncyr renewcommand sfdefault wncyss renewcommand encodingdefault ot2 normalfont selectfont declaretextfontcommand textcyr cyr pagestyle empty declaremathsizes 10 9 7 6 begin document landscape arcmin end document s long 65 04 documentclass aastex usepackage amsbsy usepackage amsfonts usepackage amssymb usepackage bm usepackage mathrsfs usepackage pifont usepackage stmaryrd usepackage textcomp usepackage portland xspace usepackage amsmath amsxtra usepackage ot2

forecasting volcanic ash dispersal and coeval resuspension during the april may 2015 calbuco eruption abstract atmospheric dispersion of volcanic ash from explosive eruptions or from subsequent fallout deposit resuspension causes a range of impacts and disruptions on human activities and ecosystems the april may 2015 calbuco eruption in chile involved eruption and resuspension activities we overview the chronology effects and products resulting from these events in order to validate an operational forecast strategy for tephra dispersal the modelling strategy builds on coupling the meteorological weather research and forecasting wrf arw model with the fall3d dispersal model for eruptive and resuspension processes the eruption modelling considers two distinct particle granulometries a preliminary first guess distribution used operationally when no field data was available yet and a refined distribution based on field measurements volcanological inputs were inferred from eruption reports and results from an argentina chilean ash sample data network which performed in situ sampling during the eruption in order to validate the modelling strategy results were compared with satellite retrievals and ground deposit measurements results indicate that the wrf fall3d modelling system can provide reasonable forecasts in both eruption and resuspension modes particularly when the adjusted granulometry is considered the study also highlights the importance of having dedicated datasets of active volcanoes furnishing first guess model inputs during the early stages of an eruption

volcanic risk assessment quantifying physical vulnerability in the built environment abstract this paper presents structured and cost effective methods for assessing the physical vulnerability of at risk communities to the range of volcanic hazards developed as part of the mia vita project 2009 2012 an initial assessment of building and infrastructure vulnerability has been carried out for a set of broadly defined building types and infrastructure categories with the likelihood of damage considered separately for projectile impact ash fall loading pyroclastic density current dynamic pressure and earthquake ground shaking intensities in refining these estimates for two case study areas kanlaon volcano in the philippines and fogo volcano in cape verde we have developed guidelines and methodologies for carrying out physical vulnerability assessments in the field these include identifying primary building characteristics such as construction material and method as well as subsidiary characteristics for example the size and prevalence of openings that may be important in assessing eruption impacts at risk buildings around kanlaon were found to be dominated by timber frame buildings that exhibit a high vulnerability to pyroclastic density currents but a low vulnerability to failure from seismic shaking around fogo the predominance of unreinforced masonry buildings with reinforced concrete slab roofs suggests a high vulnerability to volcanic earthquake but a low vulnerability to ash fall loading given the importance of agriculture for local livelihoods around kanlaon and fogo we discuss the potential impact of infrastructure vulnerability for local agricultural economies with implications for volcanic areas worldwide these methodologies and tools go some way towards offering a standardised approach to carrying out future vulnerability assessments for populated volcanic areas

volcanic hazard impacts to critical infrastructure a review abstract effective natural hazard risk assessment requires the characterisation of both hazards and vulnerabilities of exposed elements volcanic hazard assessment is at an advanced state and is a considerable focus of volcanic scientific inquiry whereas comprehensive vulnerability assessment is lacking cataloguing and analysing volcanic impacts provide insight on likely societal and physical vulnerabilities during future eruptions this paper reviews documented disruption and physical damage of critical infrastructure elements resulting from four volcanic hazards tephra fall pyroclastic density currents lava flows and lahars of eruptions in the last 100 years we define critical infrastructure as including energy sector infrastructure water supply and wastewater networks transportation routes communications and critical components common trends of impacts and vulnerabilities are summarised which can be used to assess and reduce volcanic risk for future eruptions in general tephra falls cause disruption to these infrastructure sectors reducing their functionality whilst flow hazards pyroclastic density currents lava flows and lahars are more destructive causing considerable permanent damage volcanic risk assessment should include quantification of vulnerabilities and we challenge the volcanology community to address this through the implementation of a standardised vulnerability assessment methodology and the development and use of fragility functions as has been successfully implemented in other natural hazard fields

tephra fall clean up in urban environments abstract tephra falls impact urban communities by disrupting transport systems contaminating and damaging buildings and infrastructures and are potentially hazardous to human health therefore prompt and effective tephra clean up measures are an essential component of an urban community s response to tephra fall this paper reviews case studies of tephra clean up operations in urban environments around the world spanning 50 years it identifies methods used in tephra clean up and assesses a range of empirical relationships between level of tephra accumulation and clean up metrics such as collected tephra volume costs and duration of operations results indicate the volume of tephra collected from urban areas is proportional to tephra accumulation urban areas with small tephra accumulations 1 000 m 3 km 2 or an average of 1 mm thickness may collect 50 000 m 3 km 2 or an average of 50 mm thickness remove up to 80 this relationship can inform impact and risk assessments by providing an estimate of the likely response required for a given tephra fall no strong relationship was found between tephra fall accumulation and clean up cost or duration for urban environments which received one off tephra falls suggesting that these aspects of tephra fall clean up operations are context specific importantly this study highlights the advantage of effective planning for tephra clean up and disposal in potentially exposed areas