Impact of Volcanic Eruptions on Climate

Durante el último milenio han ocurrido importantes variaciones climáticas. Luego de la Anomalía Climática Medieval tuvo lugar un prolongado período de generalizadas condiciones frías llamado Pequeña Edad de Hielo seguido por el actual Calentamiento Global . Con el Modelo de Circulación General ECHO-G se produjeron escenarios transientes que simulan las anomalías mensuales del período 1000 a 1990 AD. En este trabajo primeramente se analiza la capacidad del ECHO-G de reproducir los campos de temperatura y componente zonal del viento, ambos en el nivel de 1000hPa, en la región del cono sur de Sudamérica utilizando como referencia el re-análisis NCEP/NCAR para el período 1961-1990 testeando las diferencias de los valores medios y los desvíos estándar para la temperatura y la componente zonal del viento. En el centro norte del país el modelo ECHO-G simula temperaturas superiores a las del re-análisis NCEP-NCAR. Sin embargo, las diferencias entre el modelo y el re-análisis son menores en ...

Voluminous rhyolitic eruptions from Toba, Indonesia, and Taupo Volcanic Zone (TVZ), New Zealand have dispersed volcanic ash over vast areas in the late Quaternary. The w74 ka Youngest Toba Tuff (YTT) eruption deposited ash over the Bay of Bengal and the Indian subcontinent to the west. The w340 ka Whakamaru eruption (TVZ) deposited the widespread Rangitawa Tephra, dominantly to the southeast (in addition to occurrences northwest of vent), extending across the landmass of New Zealand, and the South Pacific Ocean and Tasman Sea with distal terrestrial exposures on the Chatham Islands. These super-eruptions involved w2500 km 3 and w1500 km 3 of magma (dense-rock equivalent; DRE), respectively. Ultra-distal terrestrial exposures of YTT at two localities in India, Middle Son Valley, Madhya Pradesh, and Jurreru River Valley, Andhra Pradesh, at distances of >2000 km from the source caldera, show a basal 'primary' ashfall unit w4 cm thick, although deposits containing reworked ash are up to w3 m in total thickness. Exposures of Rangitawa Tephra on the Chatham Islands, >900 km from the source caldera, are w15e30 cm thick. At more proximal localities (w200 km from source), Rangitawa Tephra is w55e70 cm thick and characterized by a crystal-rich basal layer and normal grading. Both distal tephra deposits are characterized by very-fine ash (with high PM 10 fractions) and are crystal-poor. Glass chemistry, stratigraphy and grain-size data for these distal tephra deposits are presented with comparisons of their correlation, dispersal and preservation. Using field observations, ash transport and deposition were modeled for both eruptions using a semi-analytical model (HAZMAP), with assumptions concerning average wind direction and strength during eruption, column shape and vent size. Model outputs provide new insights into eruption dynamics and better estimates of eruption volumes associated with tephra fallout. Modeling based on observed YTT distal tephra thicknesses indicate a relatively low (<40 km high), very turbulent eruption column, consistent with deposition from a co-ignimbrite cloud extending over a broad region. Similarly, the Whakamaru eruption was modeled as producing a predominantly Plinian column (w45 km high), with dispersal to the southeast by strong prevailing winds. Significant ash fallout of the main dispersal direction, to the northwest of source, cannot be replicated in this modeling. The widespread dispersal of large volumes of fine ash from both eruptions may have had global environmental consequences, acutely affecting areas up to thousands of kilometers from vent.

At the Plio-Pleistocene transition, three large volcanic centres in the Bukit Barisan, Sumatera, began producing voluminous amounts of felsic tephra and pyroclastic flows. Field evidence at two of the centres suggests not one but multiple paroxysmal events spanning periods of up to almost 2 million years. At Toba (now Danau Toba, northern Sumatera) perhaps four such events occurred between 1.9 Ma and about 30 ka ago. The centres are marked by several hundred metres thick of ignimbrite, pyroclastic tuff flows, and air-fall tephra. All three eruption centres should be classed in the top rank of the Volcanic Explosivity Index (VEI). Air-fall tuff has been identified at more than a dozen localities throughout Peninsular Malaysia as far east as the middle Lebir river, Kelantan, and in the upper Terengganu river reaches. Thicknesses are in the one-metre range. Recently all these Malaysian tephra have been attributed to one "Toba eruption" and assigned a 70-75 ka age ignoring the possibility of origins from the other two volcanic centres and brushing aside findings of detailed fieldwork and publications of pre-World War II vintage. Recently we studied the volcanic eruptives of the Maninjau volcanic centre in the Minang Highlands, western Sumatera, and here too evidence of multiple eruptions is present.

Significance Poor air quality is a global public health issue, contributing to millions of premature deaths per year worldwide. Low-cost air quality sensors are a promising tool to improve monitoring capabilities. In this study, we built and deployed a low-cost sensor network for emergency response during an extreme air quality event, the 2018 Kīlauea Lower East Rift Zone eruption. This network was used to estimate fine-scale population exposures to multiple pollutants, to measure the chemical transformation of volcanic emissions, and to provide real-time observations as part of emergency management efforts.

In this study of ship tracks, Moderate Resolution Imaging Spectroradiometer (MODIS) measurements from late-morning (Terra) and early-afternoon (Aqua) Earth Observing System platforms are analyzed in five separate geographically distributed cases to compare estimates of the sizes (and their changes in time) of droplets associated with ship exhaust. Ship tracks are readily detected in near-infrared imagery as bright features, especially in 2.13-μm observations. The Terra “MOD06” and Aqua “MYD06” cloud products are used to determine the effective radius of the ship-track droplets; droplet age (time in the atmosphere) is estimated as a function of the distance from the ship. Terra and Aqua MODIS estimates of droplet sizes in ship-track plumes are found to be in agreement, with a correlation greater than 0.90; for the cases studied, droplet sizes in the ship plumes are between 6 and 18 μm. Moreover, the droplets’ size growth rates inferred from the length of the ship track were found to ...

The Indonesian Young Toba Tuff (YTT), classically dated around 74 ka BP, is considered as a short-lived explosive cataclysmic super-eruption. The huge amounts of ash and SO2 emitted are likely to have triggered a volcanic winter which accelerated the transition to the last glaciation, and may have induced a human genetic bottleneck. However, the global climatic impact of the YTT or its duration are hotly debated. The present work offers a new interpretation of the Toba volcanic complex eruptive history. Analysing the BAR94-25 marine core proximal to the Toba volcanic center and combining it with high-resolution tephrostratigraphy and δ18O stratigraphy, we show that the Toba complex produced a volcanic succession that consists of at least 17 distinct layers of tephra and cryptotephra. Textural and geochemical analyses show that the tephra layers can be divided in 3 main successive volcanic activity phases (VAP1 to VAP3) over a period of ~ 50 kyr. The main volcanic activity phase, VAP...

Banjir yang terjadi di Kecamatan Gunung Meriah terjadi beberapa tahun terakhir, banyak masyarakat di Kecamatan Gunung Meriah merasakan dampak berupa kerugian serta banyak terjadi kerusakan lahan di berbagai daerah. Tujuan penelitian ini adalah untuk memetakan model jalur evakuasi banjir di Kecamatan Gunung Meriah Kabupaten Aceh Singkil yang paling efektif dengan menggunakan sistem informasi geografis. Metode yang digunakan yaitu Network Analyst dilakukan dengan menggunakan aplikasi ArcGIS Versi 10.6. Teknik pengumpulan data dilakukan menggunakan studi literatur dan dokumentasi. Metode analisis data pertama menentukan tempat evakuasi dan yang kedua menentukan jalur evakuasi menggunakan metode Network Analyst. Hasil penelitian terdapat 18 jalur evakuasi dan di 13 Shelter Area yang berada di Kecamatan Gunung Meriah. Jalur evakuasi paling aman dan efisien dengan jarak antar titik rawan dengan fasilitas evakuasi berkisar paling dekat berjarak 355 meter yaitu dari titik rawan yang berada di Desa Bukit Harapan menuju titik Shelter Area yaitu di SMAN 2 Gunung Meriah. hingga paling jauh 13.227 meter dari titik rawan yang berada di Silulusan menuju titik Shelter Area yaitu di SDN 2 Silulusan dan SDN Blok VI Baru.

The STRAP (Synergie Transdisciplinaire pour Répondre aux Aléas liés aux Panaches volcaniques) campaign was conducted in 2015 to investigate the volcanic plumes of Piton de La Fournaise (La Réunion, France). For the first time, measurements at the local (near the vent) and at the regional scales around the island were conducted. The STRAP 2015 campaign has become possible thanks to a strong cross-disciplinary collaboration between volcanologists and meteorologists. The main observations during four eruptive periods (85 days) are summarized. They include the estimates of SO&lt;sub&gt;2&lt;/sub&gt;, CO&lt;sub&gt;2&lt;/sub&gt; and H&lt;sub&gt;2&lt;/sub&gt;O emissions, the altitude of the plume at the vent and over different areas of La Réunion Island, the evolution of the SO&lt;sub&gt;2&lt;/sub&gt; concentration, the aerosol size distribution, and the aerosol extinction profile. A climatology of the volcanic plume dispersion is also reported. Simulations and measurements showed that the...

Hazard analysis at caldera volcanoes is challenging due to the wide range of eruptive and environmental conditions that can plausibly occur during renewed activity. Taupo volcano, New Zealand, is a frequently active and productive rhyolitic caldera volcano that has hosted the world&#39;s youngest known supereruption and numerous smaller explosive events. To assess ashfall hazard from future eruptions, we have simulated atmospheric ash dispersal using the Ash3d model. We consider five eruption scenarios spanning magma volumes of 0.1–500 km3 and investigate the main factors governing ash dispersal in modern atmospheric conditions. Our results are examined in the context of regional synoptic weather patterns (Kidson types) that provide a framework for assessing the variability of ashfall distribution in different wind fields. For the smallest eruptions (~0.1‐km3 magma), ashfall thicknesses &gt;1 cm are largely confined to the central North Island, with dispersal controlled by day‐to‐da...

Banjir yang terjadi di Kecamatan Gunung Meriah terjadi beberapa tahun terakhir, banyak masyarakat di Kecamatan Gunung Meriah merasakan dampak berupa kerugian serta banyak terjadi kerusakan lahan di berbagai daerah. Tujuan penelitian ini adalah untuk memetakan model jalur evakuasi banjir di Kecamatan Gunung Meriah Kabupaten Aceh Singkil yang paling efektif dengan menggunakan sistem informasi geografis. Metode yang digunakan yaitu Network Analyst dilakukan dengan menggunakan aplikasi ArcGIS Versi 10.6. Teknik pengumpulan data dilakukan menggunakan studi literatur dan dokumentasi. Metode analisis data pertama menentukan tempat evakuasi dan yang kedua menentukan jalur evakuasi menggunakan metode Network Analyst. Hasil penelitian terdapat 18 jalur evakuasi dan di 13 Shelter Area yang berada di Kecamatan Gunung Meriah. Jalur evakuasi paling aman dan efisien dengan jarak antar titik rawan dengan fasilitas evakuasi berkisar paling dekat berjarak 355 meter yaitu dari titik rawan yang berada di Desa Bukit Harapan menuju titik Shelter Area yaitu di SMAN 2 Gunung Meriah. hingga paling jauh 13.227 meter dari titik rawan yang berada di Silulusan menuju titik Shelter Area yaitu di SDN 2 Silulusan dan SDN Blok VI Baru.

Aerosol-cloud interaction effects are a major source of uncertainty in climate models so it is important to quantify the sources of uncertainty and thereby direct research efforts. However, the computational expense of global aerosol models has prevented a full statistical analysis of their outputs. Here we perform a variance-based analysis of a global 3-D aerosol microphysics model to quantify the magnitude and leading causes of parametric uncertainty in model-estimated present-day concentrations of cloud condensation nuclei (CCN). Twenty-eight model parameters covering essentially all important aerosol processes, emissions and representation of aerosol size distributions were defined based on expert elicitation. An uncertainty analysis was then performed based on a Monte Carlo-type sampling of an emulator built for each model grid cell. The standard deviation around the mean CCN varies globally between about ±30 % over some marine regions to ±40-100 % over most land areas and high latitudes, implying that aerosol processes and emissions are likely to be a significant source of uncertainty in model simulations of aerosolcloud effects on climate. Among the most important contributors to CCN uncertainty are the sizes of emitted primary particles, including carbonaceous combustion particles from wildfires, biomass burning and fossil fuel use, as well as sulfate particles formed on sub-grid scales. Emissions of carbonaceous combustion particles affect CCN uncertainty more than sulfur emissions. Aerosol emission-related parameters dominate the uncertainty close to sources, while uncertainty in aerosol microphysical processes becomes increasingly important in remote regions, being dominated by depo-sition and aerosol sulfate formation during cloud-processing. The results lead to several recommendations for research that would result in improved modelling of cloud-active aerosol on a global scale.

The Taupō eruption, also known as eruption Y, occurred in late summer to early autumn (typically late March to early April) in AD 232  10 yr at Taupō volcano, an 'inverse' caldera volcano underlying Lake Taupō in the central Taupō Volcanic Zone, North Island, Aotearoa New Zealand. The complex rhyolitic eruption, the most powerful eruption globally in the last 5000 years, lasted between several days and several weeks and generated five markedly contrasting pyroclastic fall deposits (units Y1 to Y5) followed by the extremely violent emplacement of a low-aspect-ratio ignimbrite (unit Y6). The fall deposits include three phreatomagmatic units, Y1, Y3, and Y4, the latter two being the products of archetypal phreatoplinian events; and two magmatic units, Y2 and Y5, the latter being the product of an exceptionally powerful plinian (previously described as 'ultraplinian') event with an extreme magma discharge rate around 10 8 to 10 10 kg s-1. The pyroclastic fall-generating eruptions were followed by the climactic emplacement of the entirely non-welded Taupō ignimbrite (Y6). It was generated by the catastrophic collapse of the 35 to 40-km-high plinian eruption column (Y5) that produced a very-fast-moving (600 to 900 km h-1) , hot (up to 500°C) pyroclastic flow (density current) that covered about 20,000 km 2 of central North Island over a near-circular area ~160 km in diameter, centred on Lake Taupō, in fewer than about ten to 15 minutes. This violent ground-hugging pyroclastic flow generated its own air lubrication, forming a near-frictionless basal region, and the resultant highly fluidised ignimbrite was spread as a near-continuous but thin sheet over the entire landscape, both infilling valleys and mantling ridges. Caldera collapse formed a new basin in the older Ōruanui caldera in Lake Taupo. The pressure-wave arising from the plinian-column collapse probably generated a global volcano-meteorological tsunami. Studied intensely by extraordinary volcanologists Colin Wilson and George Walker, and others, the exceptionally wellpreserved and readily-accessible Taupō eruptives provide a one-in-a-hundred classic sequence that is arguably the most informative in the global world of volcanology with respect to explosive rhyolitic eruptions and their products. The total volume of the Taupō eruptives amounts to ~35 km 3 as magma, equivalent to ~105 km 3 of bulk (loose) pyroclastic material, of which the Taupō ignimbrite comprises ~30 km 3. The impacts and landscape response of the eruption were profound, spatially extensive, and enduring, and the young glassy soils (Vitrands in Soil Taxonomy, Pumice Soils in the New Zealand Soil Classification) developed in the silica-rich pumiceous deposits, although well suited to plantation forestry (especially exotic Pinus radiata) , pose unique problems for agriculture and other land uses, including a high susceptibility to gully erosion and an inherent deficiency in cobalt and other trace elements, and require special management.

Tephra deposits are used by many disciplines of the natural sciences, not only for gaining important insight into volcanism, but also for chronological purposes, especially the dating of sedimentary sequences throughout geological time. Use of these deposits as isochronous tie points relies on the ability to accurately correlate tephra from one site to another including more diffuse, distal sites, as well as to possibly identify the source eruption. However, the ability to uniquely identify tephra deposits, and thus correlate them with certainty, is not without its complications. Here we present a case study from North Island, New Zealand, to highlight the complications and intricacies of achieving robust tephra deposit correlations. We highlight three key issues including: 1) the large uncertainties associated with direct dating techniques for older (≥1 Ma) tephra horizons; 2) the lack of/or minimalist amount of published and accessible geochemical data; and 3) the lack of data pertaining to the source regions themselves. We report new age and geochemical data for tephra deposits from a region that has been the depositional site of many eruptions since at least 12 Ma. Of the tephra horizons sampled in this region, six contained sufficient zircons for fission-track dating. Ages of the horizons range from 1.4 to 5.7 Ma, in good agreement with previously assigned age constraints based on biostratigraphic and/or paleomagnetic markers. However, the precision of these ages (2σ uncertainties of ± 0.4-1.6 Ma) is insufficient to correlate the tephra horizons to either their specific source (eruption event) or alternative tephra deposits using geochronology alone. Therefore, in addition to the new (and existing) age data, we present the results of major and trace element analysis of glass shards from 18 tephra horizons. For most horizons the geochemical signatures of the glass shards are internally homogeneous for both major and trace elements, suggesting a single source eruption. In a few cases, however, the tephra horizons exhibit heterogeneous geochemical signatures, which, when coupled with the deposit morphology, suggest evidence for reworking, post-depositional devitrification, and a more complex source history. We discuss correlation of the tephra horizons to onshore and offshore counterparts and also to source. Our results emphasise the importance of combining geochronological constraints with geochemical fingerprinting and additional parameters including stratigraphy to provide the most accurate correlations. As a result, we encourage the use of electronic storage files in publications to give access to full geochemical (including secondary standard data) and chronological datasets. This will not only allow complete characterisation of the tephra, but also facilitate rigorous statistical assessment to produce accurate correlation to other deposits in future studies.

This thesis is the first monograph dedicated to internal war as an historical phenomenon in Carthaginian (pre-Roman) North Africa; a side-lined but important aspect of the life and development of Carthage’s civilisation which has been largely unexplored and uncontextualized in previous scholarship with respect to wider Mediterranean economic and environmental processes at play in the pre-Hellenistic and Hellenistic world. Ten internal wars (including two political coup attempts) are known to have occurred from literary evidence in the final 250 years till the fall of the city to the Roman Republic (396-146 BC). The most severe of these were the Libyan initiatives referred to throughout this thesis as the First (ca. 396-392), Second (ca. 378-368), and Third (241-237) ‘Libyan Wars’. Only the last of these (also called the ‘Mercenary’ or ‘Truceless War’) is relatively well-known to scholars working outside the area of Punic Carthage. Yet the extent to which issues of supply dictated its course, from the initial military mutiny over sitarchia (‘grain-allowance’), to Carthage’s funnelling of overseas supplies away from rebels in Africa to cause a famine which constrained the violence in its fourth year, has been frequently overlooked.

Maghrebian agriculture has always been vulnerable to climatic variability and change, and Carthage’s environmental sensitivity will have grown concomitant with its territorial and urban expansion. Recognising this, a main aim of this thesis is to examine the extent to which short-term environmental perturbations acted in concourse with other historical processes, such as interstate war and demographic changes, to influence periods of rapid societal change at Carthage. This thesis is thus also the first study to apply to Carthage, after the example of recent work on Ptolemaic Egypt (Manning et al. (2017); Ludlow and Manning (2021)), the rapidly developing discourse on the relationship between climatically effective volcanic eruptions and the timing of societal stress.

Explosive volcanic eruptions in the classical period are now datable with great precision due to the development of a high-resolution ice core chronology reaching back to antiquity (Sigl et al. (2015)). Statistical testing conducted for this thesis reveals a non-random temporal association between the timing of large volcanic eruptions and the start dates of Carthage’s internal wars. Over the course of this thesis, credible mechanisms are identified which may explain the association, such as the potential of explosive eruptions to negatively affect agriculture, and thus societal stability, by impacting temperature and precipitation; impacts which are likely to be more pronounced when occurring in times of other socio-economic stresses resulting, for example, from interstate war. Climatic events are thus argued to be a meaningful but overlapping context in Carthage’s history.

In April 2007, the Piton de la Fournaise volcano (Réunion island) entered into its biggest eruption recorded in the last century. Due to the absence of a sensors network in the vicinity of the volcano, an estimation of degassing during the paroxysmal phase of the event has not been performed. Nevertheless, the SO 2 plume and aerosols have been observed by the OMI and CALIOP space sensors, respectively. The mesoscale chemical model MesoNH-C simulates the observed bulk mass of SO 2 and the general shape of the SO 2 plume spreading over the Indian Ocean. Moreover, an analysis of the SO 2 plume budget estimates a total SO 2 release of 230 kt, among of which 60 kt have been transformed into H 2 SO 4. 27 kt of SO 2 and 21 kt of H 2 SO 4 have been deposited at the surface by dry deposition. With this top down approach, the temporal evolution of the SO 2 emission has been estimated during the most active period of the eruption. The peak of degassing was estimated at 1800 kg s −1 in the morning of 6 April. The temporal evolution of SO 2 emission presented here can also be used for local studies. 1 Introduction Volcanoes represent one of the most significant natural sources of pollutants in the atmosphere, both during and between eruptions (Mather et al., 2005). Large explosive eruptions such as El Chichòn in 1982

The Indonesian Young Toba Tuff (YTT), classically dated around 74 ka BP, is considered as a short-lived explosive cataclysmic super-eruption. The huge amounts of ash and SO2 emitted are likely to have triggered a volcanic winter which accelerated the transition to the last glaciation, and may have induced a human genetic bottleneck. However, the global climatic impact of the YTT or its duration are hotly debated. The present work offers a new interpretation of the Toba volcanic complex eruptive history. Analysing the BAR94-25 marine core proximal to the Toba volcanic center and combining it with high-resolution tephrostratigraphy and δ18O stratigraphy, we show that the Toba complex produced a volcanic succession that consists of at least 17 distinct layers of tephra and cryptotephra. Textural and geochemical analyses show that the tephra layers can be divided in 3 main successive volcanic activity phases (VAP1 to VAP3) over a period of ~ 50 kyr. The main volcanic activity phase, VAP...

Banjir yang terjadi di Kecamatan Gunung Meriah terjadi beberapa tahun terakhir, banyak masyarakat di Kecamatan Gunung Meriah merasakan dampak berupa kerugian serta banyak terjadi kerusakan lahan di berbagai daerah. Tujuan penelitian ini adalah untuk memetakan model jalur evakuasi banjir di Kecamatan Gunung Meriah Kabupaten Aceh Singkil yang paling efektif dengan menggunakan sistem informasi geografis. Metode yang digunakan yaitu Network Analyst dilakukan dengan menggunakan aplikasi ArcGIS Versi 10.6. Teknik pengumpulan data dilakukan menggunakan studi literatur dan dokumentasi. Metode analisis data pertama menentukan tempat evakuasi dan yang kedua menentukan jalur evakuasi menggunakan metode Network Analyst. Hasil penelitian terdapat 18 jalur evakuasi dan di 13 Shelter Area yang berada di Kecamatan Gunung Meriah. Jalur evakuasi paling aman dan efisien dengan jarak antar titik rawan dengan fasilitas evakuasi berkisar paling dekat berjarak 355 meter yaitu dari titik rawan yang berada di Desa Bukit Harapan menuju titik Shelter Area yaitu di SMAN 2 Gunung Meriah. hingga paling jauh 13.227 meter dari titik rawan yang berada di Silulusan menuju titik Shelter Area yaitu di SDN 2 Silulusan dan SDN Blok VI Baru.

The Indonesian Young Toba Tuff (YTT), classically dated around 74 ka BP, is considered as a shortlived explosive cataclysmic super-eruption. The huge amounts of ash and SO 2 emitted are likely to have triggered a volcanic winter which accelerated the transition to the last glaciation, and may have induced a human genetic bottleneck. However, the global climatic impact of the YTT or its duration are hotly debated. The present work offers a new interpretation of the Toba volcanic complex eruptive history. Analysing the BAR94-25 marine core proximal to the Toba volcanic center and combining it with high-resolution tephrostratigraphy and δ 18 O stratigraphy, we show that the Toba complex produced a volcanic succession that consists of at least 17 distinct layers of tephra and cryptotephra. Textural and geochemical analyses show that the tephra layers can be divided in 3 main successive volcanic activity phases (VAP1 to VAP3) over a period of ~ 50 kyr. The main volcanic activity phase, VAP2, including the YTT, is likely composed of 6 eruptive events in an interval whose total duration is ~ 10 ka. Thus, we suggest that the eruptive model of the Toba volcano must be revised as the duration of the Toba volcanic activity was much longer than suggested by previous studies. The implications of re-estimating the emission rate and the dispersion of ashes and SO 2 include global environmental reconstitutions, climate change modelling and possibly human migration and evolution.

The Youngest Toba Tuff (YTT, erupted at ca. 74 ka) is a distinctive and widespread tephra marker across South and Southeast Asia. The climatic, human and environmental consequences of the YTT eruption are widely debated. Although a considerable body of geochemical data is available for this unit, there has not been a systematic study of the variability of the ash geochemistry. Intrinsic (magmatic) and extrinsic (postdepositional) chemical variations bring fundamental information regarding the petrogenesis of the magma, the distribution of the tephra and the interaction between the ash and the receiving environment. Considering the importance of the geochemistry of the YTT for stratigraphic correlations and eruptive models, it is central to the YTT debate to quantify and interpret such variations. Here, we collate all published geochemical data on the YTT glass, including analyses from 67 sites described in the literature and three new samples. Two principal sources of chemical variation are investigated: (i) compositional zonation of the magma reservoir and (ii) post-depositional alteration. Post-depositional leaching is responsible for up to ca. 11 % differences in Na 2 O/K 2 O and ca. 1 % differences in SiO 2 /Al 2 O 3 ratios in YTT glass from marine sites. Continental tephras are 2 % higher in Na 2 O/K 2 O and 3 % higher in SiO 2 /Al 2 O 3 with respect to the marine tephra. We interpret such post-depositional glass alteration as related to seawater-induced alkali migration in marine environments. Crystal fractionation and consequential magmatic differentiation, which produced order-of-magnitude variations in trace element concentrations reported in the literature, also produced major element differences in the YTT glass. FeO/Al 2 O 3 ratios vary by about 50 %, which is analytically significant. These variations represent magmatic fractionation involving Fe-bearing phases. We also compared major element concentrations in YTT and Oldest Toba Tuff (OTT) ash samples, to identify potential compositional differences that could constrain the stratigraphic identity of the Morgaon ash (western India); no differences between the OTT and YTT samples were observed.

In this leller, we report the profiles (-160 samples) of t 0 Be, 9 Be, Zn in a Mediterranean sediment core spanning the last 60 kyr. We show the existence of a 10 B e peak. whose absolute age is estimated to be 34±3 kyr BP. based on its stratigraphic position between two tephra layers originating from two volcanic eruptions (Campanian Ignimbrite and Citara). dated by K-Ar, 40 Ar-39Ar and 1 4 c methods. This peak is similar to the increase in the 10 B e concentration observed in Vostok and Dome C ice cores at the same age. The increase with approximately similar amplitude in both ice and sediment cores at different latitudes and hemispheres cannot be explained by changes in the archives. The present resuil supports the view of a well defined global enhancement of the 10 Be flux. related to an increase of the 1 0Be production rate and not to a redistribution of the 10 Be fallout between different latitudes.

Many major volcanic eruptions coincide with cooling trends of decadal or longer duration that began significantly before the eruptions. Dust veils provide positive feedback for short-term (less than 10 year) global cooling, but seem unlikely to trigger glaciations or even minor climate fluctuations in the 10to 100-year range. On the contrary, variations in climate lead to stress changes on the earth's crustfor instance, by loading and unloading of ice and water masses and by axial and spin-rate changes that might augment volcanic (and seismic) potential.

As a consequence of a large-scale volcanic outburst, the Laki eruption in 1783-84, the focus of the world turned suddenly towards Iceland, a province of the Danish crown. The dynamic volcano in Iceland had far-reaching consequences for the outside world as the pollution was carried further by the wind, causing dramatic changes in weather conditions. The temperature in Europe fell by 1.5 °C over a two-year period. Icelanders endured extreme hardship as sulphuric haze swept the country during the summer of 1783 and temperature dropped considerably for a time. The period which followed is termed 'The Famine of the Mist' in Icelandic history due to the thick fog caused by the eruption and the extreme cold weather. This article will discuss the experience the people of Iceland underwent at the time. Correspondence, which is the main source of the article, gives an intimate glimpse of people's lives during this critical period caused by the Laki eruption. The letters reveal that, albeit exhausted and traumatized, people were striving to remain optimistic. The eyes of Europe and the enlightened world of scientists were cast on Iceland during these testing times. Icelandic contacts with the outside world, despite Iceland being located far away in the North Atlantic, were various and flowed in more than one direction. The administration of Iceland was centred in Copenhagen where a plan for free trade was already in preparation at the outbreak of the eruption.

The Eldgjá eruption in Iceland in the late 930s CE seems to have had tremendous repercussions. Twenty-eight historical documents mention hardships in the aftermath of the eruption in Europe. However, only a few documents were written during the time in question. Interdisciplinary research means stepping &quot;outside&quot; of your own field. Evaluating the quality of &quot;foreign&quot; material is essential. A GIS map offers a useful methodological approach in this case: more details can be added to the data whereby the reliability of historical documents and the impact of events like the Eldgjá eruption and its regional scope become easily visible.

Large-scale volcanic plumes, either generated by discharge of material directly from a vent or developed from the top of pyroclastic flows, produce laterally spreading umbrella-shaped clouds that disperse pyroclastic material over large areas. During plinian eruptions followed by pyroclastic flows, an enormous quantity of ash particles produced both by sustained plumes and by the buoyant portion of pyroclastic flows settle far from the source and form widespread fall deposits. To fully evaluate the magnitude of the plinian phase for this kind of eruptions is fundamental for distinguishing between the different sources of fine ash. In this paper we demonstrate that the plinian and ignimbrite contribution to the distal ash fall can be discriminated based on thickness versus distance relationships. The Campanian Ignimbrite eruption (CI; 39,000 yr B.P.) in southern Italy, provides an important case study. This was a huge ignimbrite-forming explosive event preceded by a plinian outburst. We present a new distribution of the thick, stratified pumice fall deposit formed immediately before the emplacement of the ignimbrite and reconstruct the distribution of the CI-correlated tephra fall dispersed in eastern Europe and in the eastern Mediterranean Sea over an area exceeding 3Â10 6 km 2. The volumes calculated for the proximal plinian, co-plinian and co-ignimbrite deposits of the CI eruption are respectively: 4 km 3 , 16 km 3 and almost 100 km 3 .

In April 2007, the Piton de la Fournaise volcano (Réunion island) entered into its biggest eruption recorded in the last century. Due to the absence of a sensors network in the vicinity of the volcano, an estimation of degassing during the paroxysmal phase of the event has not been performed. Nevertheless, the SO 2 plume and aerosols have been observed by the OMI and CALIOP space sensors, respectively. The mesoscale chemical model MesoNH-C simulates the observed bulk mass of SO 2 and the general shape of the SO 2 plume spreading over the Indian Ocean. Moreover, an analysis of the SO 2 plume budget estimates a total SO 2 release of 230 kt, among of which 60 kt have been transformed into H 2 SO 4. 27 kt of SO 2 and 21 kt of H 2 SO 4 have been deposited at the surface by dry deposition. With this top down approach, the temporal evolution of the SO 2 emission has been estimated during the most active period of the eruption. The peak of degassing was estimated at 1800 kg s −1 in the morning of 6 April. The temporal evolution of SO 2 emission presented here can also be used for local studies. 1 Introduction Volcanoes represent one of the most significant natural sources of pollutants in the atmosphere, both during and between eruptions (Mather et al., 2005). Large explosive eruptions such as El Chichòn in 1982

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.

Significant new information shows that the Campanian Ignimbrite (CI) eruption from the Phlegrean Fields, southern Italy, was much larger than hitherto supposed and in fact one of the largest late Quaternary explosive events. The eruption can be dated to 40,000 calendar years ago, within the interval of the so-called Middle to Upper Paleolithic 'transition'. Its position can be precisely correlated with a number of other environmental events, including Heinrich Event 4 (HE4), the Laschamp excursion, and a particular cosmogenic nuclide peak. In view of this unique combination of factors, we studied the CI volcanic catastrophe with particular attention to its impact on climate and human ecosystems, including potential interference with ongoing processes of cultural evolution (biological evolution is best left aside for the moment). The contribution of this research is chronological and ecological. The CI volcanic event provides an unequalled means of correlating stratigraphic sequences across Western Eurasia, either directly or indirectly, and affords a unique opportunity to establish the age and climatic context of important archaeological sequences. Ecologically, the CI eruption inevitably interacted with the beginning of HE4 in terms of atmospheric feedback systems. Their combined forcing produced a sudden and at least hemispheric climatic deterioration; a 'volcanic winter' scenario cannot be ruled out. Paleolithic occupation was severely altered throughout the direct-impact zone of the eruption and likely along fringe areas in southern and southeastern Europe. The above observations call for a reconsideration of the processes and rhythms involved in the Middle to Upper Paleolithic 'transition'. A tentative model is suggested that links the exceptional environmental stress at 40,000 BP with processes already active in Paleolithic societies, leading to a period of accelerated change in cultural configurations. These eventually evolved into an Upper Paleolithic proper at a later date. The evidence to invoke allochthonous cultural input or invasionist scenarios is not considered compelling.

Significance The Tierra Blanca Joven eruption of Ilopango occurred during Maya times but the exact timing and its impact have been controversial. It was thought to be responsible for the anomalously cold decade experienced in the Northern Hemisphere centered at 540 CE, but this date is at odds with archeological evidence that suggests a date near the start of the Early Classic Period (pre-450 CE). Our precise age of 431 ± 2 CE allows us to pinpoint the eruption in proxy records and shows that its impact was apparently limited. It appears to have only had major effects on populations within ∼80 km of the volcano, where the regions were blanketed by decimeters of ash fallout and pyroclastic density currents.

ABSTRAK Pola penyebaran konsentrasi SO 2 (sulfur dioksida) sangat dipengaruhi oleh parameter cuaca dan dapat disimulasikan pola sebarannya dengan menggunakan model dispersi kualitas udara. Penelitian ini mensimulasikan pola penyebaran SO 2 pascameletusnya Gunung Sinabung di Provinsi Sumatra Utara pada tanggal 29 Oktober 2013 dengan mengaplikasikan model dispersi HYSPLIT. Masukan data yang digunakan adalah data prediksi cuaca luaran model Weather Research Forecasting (WRF) resolusi 25 km dengan input emisi SO 2 hasil pengukuran fluks gas. Hasil luaran model secara umum menggambarkan pola dispersi SO 2 sesuai dengan kondisi lapangan, baik arah sebaran maupun cakupan daerah terdampak. Sebaran SO 2  5 menit pasca erupsi G. Sinabung mencapai radius 6,7 - 8,1 km dengan nilai konsentrasi SO 2 maksimum sebesar 0,065 mg/m 3 . Aplikasi model dispersi bersamaan dengan model prediksi cuaca dapat diterapkan di Indonesia sebagai sistem peringatan dini sebaran SO 2 akibat erupsi gunung api.  Kata ...