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As the second common type of volcanic vent on Earth, maar-diatreme volcanoes and their post-eruptive lacustrine sediments are a main focus of volcanology, palaeolimnology, palaeoclimatology and palaeontology. A number of maar-type volcanoes have been found in Leizhou Peninsula, South China, but little is known about their eruption processes and detailed stratigraphy of the post-eruptive sediments. We present a combined geophysical and geological analysis to study the eruptive history and post-eruptive sediment stratigraphy of a large maar, the elliptical (1.8 × 3.0 km2) Jiudouyang (JDY) maar. The lacustrine stratigraphy revealed by drilling cores shows that the JDY maar lake has three major stages of evolution: (i) deep-lake sedimentary environment characterized by high autochthonous diatom productivity; (ii) shallow lake to swamp with very low water levels, characterized by a high total organic carbon (TOC) and abundant wood fragments; and, (iii) intermittent shallow lake and alluvial deposits composed of clay minerals and sand. The electrical resistivity tomography (ERT) values and lithological features are highly consistent, which clearly reveal the presence of ca. 50 m thick lacustrine sediments, directly underlain by a ca. 70 m thick basaltic lava rather than diatreme breccia in the crater. This infill sequence implies an alternation of eruption style from phreatomagmatic to Strombolian and/or lava flow, due to high magma flux and ascent rate of the Hainan Plume during the middle Pleistocene. The ERT data also reveal the initial phreatomagmatic crater floor at ca. 120 m depth. The initial crater had a large diameter/depth ratio (ca. 17), with an elongated shape (major axis to minor axis = 0.6), implying possible lateral vent migration during the eruption. A significant erosion under tropical weathering condition during the last few hundred thousand years, accounted for the large size of the maar crater. The study provides insights into the eruptive history and post-eruptive evolution of a large maar, as well as the spatial distribution of the lacustrine sediments. [ABSTRACT FROM AUTHOR]

The projects of social history, disaster studies, and archaeology deliberately tend to eschew consideration of events, focusing instead on processes and structures that unfold gradually over time. The eruption of the Somma-Vesuvius volcano in Campania, Italy, in 472 presents tangible markers of a specific moment, although the absence of local textual evidence and the strong hints of rapid re-exploitation of the rich and fertile soils of the region suggest that the scale of the disaster that it precipitated was limited. A perspective on the eruption informed by the concepts of risk and vulnerability demonstrates that the population of the Campanian Plain had different experiences of the eruption according to factors such as their location, the nature and robustness of their social and economic resources, and their mechanisms for accessing and exploiting power relationships. [ABSTRACT FROM AUTHOR]

Late Cretaceous records of environmental change suggest that Deccan Traps (DT) volcanism contributed to the Cretaceous-Paleogene boundary (KPB) ecosystem crisis. However, testing this hypothesis requires identification of the KPB in the DT. We constrain the location of the KPB with high-precision argon-40/argon-39 data to be coincident with changes in the magmatic plumbing system. We also found that the DT did not erupt in three discrete large pulses and that 90% of DT volume erupted in 1 million years, with ~75% emplaced post-KPB. Late Cretaceous records of climate change coincide temporally with the eruption of the smallest DT phases, suggesting that either the release of climate-modifying gases is not directly related to eruptive volume or DT volcanism was not the source of Late Cretaceous climate change. [ABSTRACT FROM AUTHOR]

Temporal correlation between some continental flood basalt eruptions and mass extinctions has been proposed to indicate causality, with eruptive volatile release driving environmental degradation and extinction. We tested this model for the Deccan Traps flood basalt province, which, along with the Chicxulub bolide impact, is implicated in the Cretaceous-Paleogene (K-Pg) extinction approximately 66 million years ago. We estimated Deccan eruption rates with uranium-lead (U-Pb) zircon geochronology and resolved four high-volume eruptive periods. According to this model, maximum eruption rates occurred before and after the K-Pg extinction, with one such pulse initiating tens of thousands of years prior to both the bolide impact and extinction. These findings support extinction models that incorporate both catastrophic events as drivers of environmental deterioration associated with the K-Pg extinction and its aftermath. [ABSTRACT FROM AUTHOR]

Evidence of Mount Etna's early volcanism is hidden by the products of its continuously intense volcanic activity. Etna's volcanism has buried most of the onshore geological record, and the poorly known offshore extent of these volcanic deposits further limits understanding the volcano's history. We obtained and analyzed new high-resolution offshore aeromagnetic data along the Ionian continental margin of Mount Etna and combined these with recent paleomagnetic data and available geological information. Specifically, we calculated a three-dimensional (3-D) magnetic inversion model of the thickness variations of the offshore Etnean volcanic system. The inversion model highlights E-W and N-S tabular lava flows associated with the Basal Tholeiitic (ca. 500 ka) and Timpe (ca. 220-110 ka) volcanic phases. These early Etna products, considering the onshore and offshore sectors, achieved total volumes of ~26 km3 and 77 km3, respectively. Moreover, the magnetic anomalies reveal several gravitational collapses that may be indicative of the submarine instabilities of Etna's eastern flank. The findings shed new light on the history of Mount Etna and its early offshore phases. The observed geometry of these early products links the magma distribution to a recently discovered system of faults that can be associated with the presence of a lateral slab-tearing mechanism during the Ionian subduction. [ABSTRACT FROM AUTHOR]

South Africa (SA) is influenced by anthropogenic SO 2 emissions, however, no studies exist detailing the atmospheric or climatic effects resulting from volcanic eruptions at this location. In this work, the Calbuco volcano situated in southern Chile (41.79°S, 73.13°W), was used as a case study to investigate the transport of volcanic SO 2 plumes over SA in 2015. The Calbuco volcano underwent a series of eruptive phases starting from 22 April 2015. In this study, HYSPLIT forward trajectories and cluster analysis were carried out in order to estimate the altitude level of air parcels entering the SA subcontinent. These analyses along with Ozone Monitoring Instrument (OMI) assessments confirmed that trajectories beginning in Calbuco arrived in SA during the last few days of April (∼28 April 2015) and stayed until the 1st week of May 2015 (∼2 May 2015). In order to estimate the rise in SO 2 columnar concentrations at various altitudes and surface SO 2 levels, OMI data and 19 ground-based (GB) monitoring stations (situated throughout SA) were utilized. A comparative analysis employing SO 2 data from pre-2014 and post-2016 volcanic eruption periods were also included in this study. Results showed that a major increase in SO 2 concentration was observed at the Planetary Boundary Layer ( ∼ 2 DU) when compared to its upper layers during April and May 2015. Although some GB stations in North West province namely Damonsville, Mmabatho and Phola showed a moderate increase in SO 2 values during April and May 2015, there was no significant rise in GB measurements at the surface in other locations However, we are not certain due to data gaps in the measurements and non-availability of ground-based measurements. [ABSTRACT FROM AUTHOR]

Cuicuilco es un sitio arqueológico que yace bajo la lava basáltica del volcán Xitle y del que conocemos únicamente algunos de sus restos. Se le ha visto como parte de una secuencia cultural unilineal que va de Tlatilco a Cuicuilco, Teotihuacan, Tula y finalmente Tenochtitlan. Cuicuilco ha sido considerado como el ejemplo más temprano del desarrollo del urbanismo, que se detuvo debido a una erupción volcánica. El análisis de la información geológica y arqueológica permite estudiar aspectos de un asentamiento con características particulares, diferentes de Teotihuacan. [ABSTRACT FROM AUTHOR]

El artículo discurre sobre la historia del sitio arqueológico de Cuicuilco en México, así como el abandono de la ciudad por la erupción del volcán Xitle circa 250 d.C.

Worst-case or high-end subduction-related earthquakes and tsunamis of 2004 and 2011 are painfully fresh in our memories. High-end subduction-related volcanic eruptions have not occurred in recent memory, so we review historical and geologic evidence about such eruptions that will surely recur within coming centuries. Specifically, we focus on Volcanic Explosivity Index (VEI) 7 eruptions, which occur 1-2 times per thousand years. A variety of environmental changes followed the VEI 7 eruption of Rinjani (Samalas), Indonesia, in CE 1257 and several more eruptions of VEI 6 or 7 that occurred in the succeeding few centuries. The Rinjani eruption and its impacts are relatively well documented, modeled, and, for the purposes of attribution, uncomplicated by antecedent eruptions. It seems likely that the Rinjani eruption triggered the onset of the Little Ice Age, and subsequent large eruptions sustained it. Although climatic effects of eruptions like Pinatubo (Philippines) and even Tambora (Indonesia) lasted only a few years, it seems that coupling of oceans, sea ice, and atmosphere after larger eruptions can force decade- to century-long cooling, decreased precipitation, and major impacts on crops. The next VEI 7 will affect a world very different from that of CE 1257. Today, populations within 100 km of candidate volcanoes range from fewer than 1000 people in remote areas to between 20 and 30 million people near several candi dates in Indonesia and the Philippines. If a VEI 7 eruption occurs, those populations will be at dire risk, and eruptions in some locations could destabilize financial centers, national economies, and even peace between nations. Distal effects on air travel, the global positioning system, and climate will be felt by a high-technology, globally interdependent world. We suggest and apply criteria to identify candidates for future VEI 7 eruptions, and discuss likely challenges for short-range forecasting of such events. Preparation for such low-probability but high-consequence events is difficult to imagine, yet some modest early measures can be considered. Volcanologists should refine geologic histories and ensure at least baseline monitoring of candidate volcanoes, and consider how they will judge the likelihood that an impending eruption will be of VEI 7. Forward-thinking governments and industries would be wise to consider how a proximal or distal VEI 7 eruption will affect their jurisdictions, and what responses make the most economic and sociopolitical sense. [ABSTRACT FROM AUTHOR]

To investigate the pre-50 ka eruption history of Towada volcano, northeastern Japan, optically stimulated luminescence (OSL) dating was applied to fine-grained quartz extracted from Late Pleistocene tephric loess intercalated with Towada tephra layers in a sediment core from the Kamikita Plain. The bulk OSL signal was found to be unsuitable for dating, because the medium and slow-1 components were thermally unstable. After a deconvolution of the bulk OSL signal to extract the fast component, the equivalent dose was estimated by using the single-aliquot regenerative-dose protocol. The OSL ages obtained for the tephric loess were generally in agreement with the stratigraphic sequence in the interval from 2.10 to 7.45 m depth, where they ranged from 156 ± 12 ka to 49 ± 3 ka, in ascending order. We calculated the ages of CP, SP, RP, and KbP tephras by interpolating OSL ages; these are 111 ± 6 ka, 89 ± 6 ka, 61 ± 4 ka, and 58 ± 4 ka, respectively; these ages are broadly concordant with previous estimates. The age of the RP tephra is of particular importance because its eruption marked the beginning of the caldera-forming stage of Towada volcano. Our results show that this eruption occurred about 20 ka younger than previously thought (ca. 80 ka). Our results demonstrate that OSL dating of quartz grains in tephric loess can be used to estimate the ages of intercalated tephra layers and contribute to our understanding of the eruption histories of volcanoes. [ABSTRACT FROM AUTHOR]

The Lar Dam was constructed from 1974 to 1980 in the Lar River valley at the foot of the Damavand Volcano. The valley walls consist of Mesozoic limestone and Quaternary volcanic rocks, overlain by thick lacustrine deposits. Prior to dam construction, a few sinkholes were observed in the reservoir area, but after impoundment, several new sinkholes formed and leakage occurred through downstream springs. Despite extensive treatment works, the reservoir has currently impounded only 40% of its designed capacity, about 35 years after the commencement of operations. The Lar Reservoir is located inside the area of a large palaeo-lake, which formed as a result of blockage of the river valley by eruption of the Damavand Volcano during the Pleistocene. This lake existed for thousands of years, developing deep karst conduits in the limestone below the volcanic rocks toward downstream springs. With the construction of the Lar Reservoir, relict karst conduits were revived and leakage occurred. Two paths are proposed for reservoir leakage, considering the region's historical geology, present hydrogeological setting, tracer tests and isotopic studies, as well as the response of spring discharge and borehole water level to reservoir filling. [ABSTRACT FROM AUTHOR]

This article presents an alternative approach to dating the volcanic eruption of Santorini, which is important for the absolute chronology of the entire Eastern Mediterranean, based on two aspects: 1. the characteristics of archaeological periods as well as the methods of assigning dates to them 2. the quality of the archaeological features used for synchronisation, along with the need to consider the time between the production of an object and its deposition, especially in terms of influences and for imported objects. As a result, the volcanic eruption need not have taken place 'late' or 'at the end' of LM IA. The eruption may have taken place in 1613±13 BC, that is, the 14C date obtained for a branch of an olive-tree from Santorini; this places it during LM IA, while LM IA nonetheless overlapped with the beginning of the New Kingdom in Egypt, traditionally dated to c. 1540 BC. In addition, we should bear in mind that the dates for the reigns of the pharaohs in the early New Kingdom should be regarded with a certain amount of flexibility. - The approach presented here is applied to periods up to the end of the Aegean Bronze Age. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses articles in the issue on topics including history of volcanic eruptions, earthquake in Europe and history of underground explosions in the U.S.

Due to its burial by the eruption of Vesuvius in AD 79, the level of biological preservation in the Roman town of Herculaneum is very high. The recovery and analysis of large quantities of material from the city's Cardo V sewer has provided the rare opportunity to study the diet of middle and lower class Romans living in an urban context in mid-1st century AD Italy. The sewer lacked an outflow point and instead functioned as a cesspit to collect the human and kitchen waste generated by those living in the multi-storey shop and apartment complex (Insula OrientalisII) situated above. In total, 220 l of soil was examined for carbonised and mineralised material, seashells, eggshells, otoliths and fish bones. 194 taxa were identified, including 94 botanical, 45 fish, 53 shellfish and two bird taxa. One-hundred and thirteen of the 194 taxa can be considered edible foodstuffs indicating a high level of dietary diversity. This article compares preservation conditions with those found in Pompeii and assess diet in relation to these findings. The level of preservation is found to be comparable between the two sites and no major taphonomic biases are observed. The diet of non-elite individuals in Herculaneum is found to consist of a few staple foods that are frequently supplemented by a wide range of other goods. Subtle differences in diet are observable within the sewer assemblage, most likely related to differences in wealth. [ABSTRACT FROM AUTHOR]

Large tropical volcanic eruptions can have considerable impact on climates and societies far away from the physical source of the eruption. Past examples of how volcanism caused abrupt climatic changes, and how societies responded to such changes, may provide us with potential lessons to help us better prepare for the changes that climate change will bring. This paper explores the climatic, agricultural and societal responses to tropical eruptions in the Finnish province of Southern Ostrobothnia during the seventeenth century. Our results suggest that in the studied area more than half of the seventeenth-century agricultural crises which had traceable human consequences resulted from volcanism caused cooling. A sharp agricultural response followed every large tropical eruption. Moreover, sudden impoverishment, and in some cases even elevated mortality and famine, succeeded these agricultural crises. Thus, there is strong evidence that climatic changes caused by volcanism can directly paralyze sensitive food systems that are based on primary production. In this regard, if geoengineering solutions, like emulating volcanic forcing to cool global climate, are considered to be a future mitigation strategy, the case study presented here stresses the need to explore all possible unintended human consequences of any such solutions. [ABSTRACT FROM AUTHOR]

Numerous volcanoes in the Afar Triangle and adjacent Ethiopian Rift Valley have erupted during the Quaternary, depositing volcanic ash ( tephra ) horizons that have provided crucial chronology for archaeological sites in eastern Africa. However, late Pleistocene and Holocene tephras have hitherto been largely unstudied and the more recent volcanic history of Ethiopia remains poorly constrained. Here, we use sediments from lakes Ashenge and Hayk (Ethiopian Highlands) to construct the first <17 cal ka BP tephrostratigraphy for the Afar Triangle. The tephra record reveals 21 visible and crypto-tephra layers, and our new database of major and trace element glass compositions will aid the future identification of these tephra layers from proximal to distal locations. Tephra compositions include comendites, pantellerites and minor peraluminous and metaluminous rhyolites. Variable and distinct glass compositions of the tephra layers indicate they may have been erupted from as many as seven volcanoes, most likely located in the Afar Triangle. Between 15.3−1.6 cal. ka BP, explosive eruptions occurred at a return period of <1000 years. The majority of tephras are dated at 7.5−1.6 cal. ka BP, possibly reflecting a peak in regional volcanic activity. These findings demonstrate the potential and necessity for further study to construct a comprehensive tephra framework. Such tephrostratigraphic work will support the understanding of volcanic hazards in this rapidly developing region. [ABSTRACT FROM AUTHOR]

Quaternary and late Neogene volcanism is widespread in northeastern Australia, producing at least 397 eruptions covering more than 20,000 km 2 , including at least 20 flows over 50 km long. Despite this abundance of young volcanism, before this study numerous eruptions had tentative ages or were undated, and the area requires a comprehensive evaluation of eruption patterns through time. To help address these issues we applied multi-collector ARGUS-V 40 Ar/ 39 Ar geochronology to determine the age of four of the younger extensive flows: Undara (160 km long, 189 ± 4/4 ka; 2σ, with full analytical/external uncertainties), Murronga (40 km long, 153 ± 5/5 ka), Toomba (120 km long, 21 ± 3/3 ka), and Kinrara (55 km long, 7 ± 2/2 ka). Verbal traditions of the Gugu Badhun Aboriginal people contain features that may potentially describe the eruption of Kinrara. If the traditions do record this eruption, they would have been passed down for 230 ± 70 generations – a period of time exceeding the earliest written historical records. To further examine north Queensland volcanism through time we compiled a database of 337 ages, including 179 previously unpublished K-Ar and radiocarbon results. The compiled ages demonstrate that volcanic activity has occurred without major time breaks since at least 9 Ma. The greatest frequency of eruptions occurred in the last 2 Ma, with an average recurrence interval of <10–22 ka between eruptions. Activity was at times likely more frequent than these calculations indicate, as the geochronologic dataset is incomplete, with undated eruptions, and intraplate volcanism is often episodic. The duration, frequency, and youthfulness of activity indicate that north Queensland volcanism should be considered as potentially still active, and there are now two confirmed areas of Holocene volcanism in eastern Australia – one at each end of the continent. More broadly, our data provides another example of 40 Ar/ 39 Ar geochronology applied to Holocene and latest Pleistocene mafic eruptions, further demonstrating that this method has the ability to examine eruptions and hazards at the youngest volcanoes on Earth. [ABSTRACT FROM AUTHOR]

Despite the occurrence of exceptionally large eruptions in the Indonesian Archipelago in recent historic times (i.e. Krakatoa 1883, Tambora 1815), no historic tephra beds have been widely identified in the terrestrial realm that could facilitate the correlation of equivalent aged sequences and/or archaeological remains. This study has identified one such tephra bed of 13th Century age that can be correlated throughout central-east Java and now can be unequivocally correlated with the Samalas 1257 A.D. tephra recently described from Lombok. The occurrence of this historic tephra marker extending ≥650 km west from its eruptive source provides the first opportunity to effect inter-regional correlation over large swathes of central Indonesia. It remains entirely conceivable that in the aftermath of this exceptionally large eruptive event there was considerable westward disruption to subsistence agriculture and trade, food shortages and famine, dislocation of affected populations and socio-political unrest on a scale that equalled or exceeded the catastrophic effects documented from the more recent Tambora 1815 A.D. eruption. Indeed the effects of this mid-13th Century eruption can be registered globally in a variety of records from Antarctica, Europe, Middle East and the Americas. Unfortunately, archaeological evidence indicating such disruption in mid-13th Century Indonesia is yet to be deciphered from the so-far sparse accounts and inscriptions of that time. However, this paucity of evidence does not diminish the utility of this widespread tephra bed as a unique chronostratigraphic marker for archaeological studies across large areas of central Indonesia. [ABSTRACT FROM AUTHOR]

The immediate local impacts of the eruption of Mount Tambora, Sumbawa, Indonesia in April 1815 were devastating, resulting in the loss of an estimated 60 000 lives on this and neighbouring islands. However, the longer term effects of the largest known historical eruption on global weather and climate and the related consequences for human health and wellbeing have maintained the prominence of the eruption in public memory. Among the most notable effects were global weather anomalies the following year, which has come to be referred to as 'the year without summer'. Scholars across the sciences and humanities continue to investigate the eruption, seeking insights into the likely meteorological and societal impacts of future volcanic eruptions. The bicentenary of the 'year without summer' in 2016 provides a timely moment to revisit this weather episode. In this paper, we draw on a range of archival materials and contemporary publications to reconstruct the weather year and explore how the summer of 1816 was experienced and recorded across the UK. We also wish to demonstrate the importance of historical contingency in understanding the potential implications of the event at the local level, and of situating events within their appropriate temporal context. We do this by considering the summer of 1816 as set against the wider weather and cultural contexts of the 1810s. Our findings illustrate that in a UK context, summer 1816 was characterised by unusual and extreme weather events. Importantly it also took place within a sequence of years that were similarly replete with anomalous and challenging weather conditions. [ABSTRACT FROM AUTHOR]

We discuss elastostatic effects on Mt. Fuji, the tallest volcano in Japan, due to historic earthquakes in Japan. The 1707 Hoei eruption, which was the most explosive historic eruption of Mt. Fuji, occurred 49 days after the Hoei earthquake (Mw 8.7) along the Nankai Trough. It was previously suggested that the Hoei earthquake induced compression of a basaltic magma reservoir and unclamping of a dike-intruded region at depth, possibly triggering magma mixing and the subsequent Plinian eruption. Here, we show that the 1707 Hoei earthquake was a special case of induced volumetric strain and normal stress changes around the magma reservoir and pathway of Mt. Fuji. The 2011 Tohoku earthquake (Mw 9), along the Japan Trench, dilated the magma reservoir. It has been proposed that dilation of a magma reservoir drives the ascent of gas bubbles with magma and further depressurization, leading to a volcanic eruption. In fact, seismicity notably increased around Mt. Fuji during the first month after the 2011 Tohoku earthquake, even when we statistically exclude aftershocks, but the small amount of strain change (< 1 μ strain) may have limited the ascent of magma. For many historic earthquakes, the magma reservoir was compressed and the magma pathway was wholly clamped. This type of interaction has little potential to mechanically trigger the deformation of a volcano. Thus, Mt. Fuji may be less susceptible to elastostatic effects because of its location relative to the sources of large tectonic earthquakes. As an exception, a possible local earthquake in the Fujikawa-kako fault zone could induce a large amount of magma reservoir dilation beneath the southern flank of Mt. Fuji. [ABSTRACT FROM AUTHOR]

The interlayers of the cryptotephra of different episodes of the catastrophic eruption of the Baitoushan volcano (Paektu-san, Changbaishan-Tianchi) in the 10th century were discovered in the sedimentary cover of Amur Bay in the Sea of Japan by the geochemical and paleomagnetic characteristics. The petrochemistry of the volcanic glass indicates the possible occurrence of pyroclastic material in the B-Tm layer and more recent episodes that have not been identified before in the sediments of the Sea of Japan. The impact of the eruption on the bay environment is noted. It is shown that the medieval state of Balhae occupying vast areas and adjacent to the volcano no longer existed after the more earlier episodes of eruption. [ABSTRACT FROM AUTHOR]

The soils of Jeju Island contain naturally abundant nickel originating from prehistoric volcanic activity. Nickel is a known human carcinogen via inhalation exposure. A risk assessment of soil particle inhalation was conducted for the first time in Korea through the analysis of soil and air data obtained from agricultural sites. Sixteen sites in Jeju were selected—13 farms, 2 citrus orchards, and 1 ranch. Forty-four soil samples were taken from these sites and analyzed for nickel content. Total suspended solids (TSP) and particulate matter up to 10 µm in size (PM10) were measured directly from the agricultural sites, and nickel concentrations in TSP and PM10 were quantified for use in the inhalation risk assessment. We conducted a probabilistic inhalation risk analysis using monitoring data obtained from the 16 sites on Jeju Island. Risk assessment procedures followed both the Korean Ministry of Environment and the U.S. Environmental Protection Agency (USEPA) risk assessment methodologies. The cancer risk associated with inhalation followed by application of the Korean risk assessment approach ranged from 4.98 × 10−9to 3.43 × 10−7, whereas the cancer risk associated with inhalation followed by application of the USEPA risk assessment approach ranged from 3.40 × 10−9to 3.74 × 10−7. This study demonstrates that no carcinogenic risk is associated with inhalation in Jeju, based on a lower cancer risk limit of 10−6. [ABSTRACT FROM AUTHOR]

Observations obtained with the near-infrared camera NIRC2, coupled to the adaptive optics system on the 10-m W.M. Keck II telescope on Mauna Kea, Hawaii, on 14 August 2007 revealed an active and highly-energetic eruption at Pillan at 245.2 ± 0.7°W and 8.5 ± 0.5°S. A one-temperature blackbody fit to the data revealed a (blackbody) temperature of 840 ± 40 K over an area of 17 km 2 , with a total power output of ∼500 GW. Using Davies’ (Davies, A.G. [1996]. Icarus 124(1), 45–61) Io Flow Model, we find that the oldest lava present is less than 1-2 h old, having cooled down from the eruption temperature of >1400 K to ∼710 K; this young hot lava suggests that an episode of lava fountaining was underway. In addition to an examination of this eruption, we present data of the Pele and Pillan volcanoes obtained with the same instrument and telescope from 2002 through 2015. These data reveal another eruption at Pillan on UT 28 June 2010. Model fits to this eruption yield a blackbody temperature of 600–700 K over an area of ∼60 km 2 , radiating over 600 GW. On UT 18 February 2015 an energetic eruption was captured by the InfraRed Telescope Facility (IRTF) via mutual event occultations. The eruption took place at 242.7 ± 1°W and 12.4 ± 1°S, i.e., in the eastern part of Pillan Patera. Subsequent observations showed a gradual decrease in the intensity of the eruption. Images obtained with the Keck telescope on 31 March and 5 May 2015 revealed that the locations of the eruption had shifted by 120–160 km to the NW. In contrast to the episodicity of Pillan, Pele has been persistent, observed in every appropriate 4.7 μm observation. Pele was remarkably consistent in its thermal emission from the Galileo era through February 2002, when a blackbody temperature of 940 ± 40 K and an area of 6.5 km 2 was measured. Since that time, however, the radiant flux from what is likely a apparently large, overturning lava lake has gradually subsided over the next decade by a factor of ∼4, while the location of the thermal source was moving back and forth between areas roughly ∼100 km to the W of the 2002 location and an area roughly ∼100 km to the SE of the 2002 location. [ABSTRACT FROM AUTHOR]

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The article explores the eruptive stage of the Caldeira Volcano in Faial Island of Azores archipelago in Portugal. Topics mentioned include the geologic units in Faial volcanostratigraphy that reflect the eruptive history of the island, ages of eruptions from the Caldeira Volcano, and examination of wood fragments in a pyroclastic density current deposit associated with the eruption.

La Garrotxa Volcanic Field (GVF) in the NE Iberian Peninsula is one of the Quaternary alkaline volcanic provinces that form part of the European Cenozoic Rift System. Active over the last 0.7 Ma, the most recent dated eruption in this volcanic zone took place in the early Holocene (11-13 ka). Its volcanic activity has varied from Hawaiian to violent Strombolian, with numerous episodes of phreatomagmatic activity, and is controlled by the main regional normal faults generated during the Neogene extension that affected the area. Despite the potential for future eruptions and the fact that this is a densely populated industrial area, no volcanic hazard assessment of the field has ever been conducted. In this work, we present the first comprehensive evaluation of the volcanic hazard in the GVF via (1) an evaluation of its volcanic susceptibility, (2) a temporal recurrence rate analysis, (3) a simulation of different eruptive scenarios, such as lava flows, pyroclastic density currents and ashfall, and (4) the elaboration of a qualitative hazard map. The final hazard map shows that the GVF can be subdivided into five different hazard levels, knowledge that will be useful for land-use management and the drawing up of emergency plans. [ABSTRACT FROM AUTHOR]

The 1963 AD eruption of Agung volcano was one of the most significant twentieth century eruptions in Indonesia, both in terms of its explosivity (volcanic explosivity index (VEI) of 4+) and its short-term climatic impact as a result of around 6.5 Mt SO emitted during the eruption. Because Agung has a significant potential to generate more sulphur-rich explosive eruptions in the future and in the wake of reported geophysical unrest between 2007 and 2011, we investigated the Late Holocene tephrostratigraphic record of this volcano using stratigraphic logging, and geochemical and geochronological analyses. We show that Agung has an average eruptive frequency of one VEI ≥2-3 eruptions per century. The Late Holocene eruptive record is dominated by basaltic andesitic eruptions generating tephra fall and pyroclastic density currents. About 25 % of eruptions are of similar or larger magnitude than the 1963 AD event, and this includes the previous eruption of 1843 AD (estimated VEI 5, contrary to previous estimations of VEI 2). The latter represents one of the chemically most evolved products (andesite) erupted at Agung. In the Late Holocene, periods of more intense explosive activity alternated with periods of background eruptive rates similar to those at other subduction zone volcanoes. All eruptive products at Agung show a texturally complex mineral assemblage, dominated by plagioclase, clinopyroxene, orthopyroxene and olivine, suggesting recurring open-system processes of magmatic differentiation. We propose that erupted magmas are the result of repeated intrusions of basaltic magmas into basaltic andesitic to andesitic reservoirs producing a hybrid of bulk basaltic andesitic composition with limited compositional variations. [ABSTRACT FROM AUTHOR]

Mt. Vesuvius is one of the most studied volcanoes in the world and its proximity to an extremely populated area makes it also one of the most threatening. Violent Strombolian (VS) events have occurred in the most recent history of the volcano, and they are the type most likely to occur in case of reactivation of the volcano in the near future. In order to investigate the dynamics and hazard of this type of eruption, we performed new field and laboratory work and numerical simulations of plume dynamics, fallout and tephra dispersal associated with such eruptions. Attention was specifically focused on the 1906 eruption, a recent and well-studied VS event. Based on new field analyses and historical observations, we reconstructed the temporal evolution of eruption source conditions during the event. The reconstructed explosive phase of the eruption is inferred to have been 8 days long and characterized by two distinct stages: a former short and intense period with sustained convective plume fed by powerful lava fountains (20 h) followed by a prolonged and less intense period of ash emission (172 h). The total grain-size distributions for both phases, used as inputs to the model, were obtained by field work and laboratory analyses. Based on these new volcanological data and reconstruction of wind field direction and intensity, partially derived from historical sources, the 1906 event was numerically simulated and results compared to deposit distributions. The modelling outcomes for the ash emission phase provide a better agreement with the measured tephra mass load for a simulation run in which ash aggregation (described by the models of Cornell et al. J Volcanol Geotherm Res 17:89-109, , and Biass et al. Nat Hazard Earth Syst Sci 14:2265-2287, ) is specifically taken into account, confirming the importance of this process during tephra dispersal. The aggregation model that best fits the simulated results to the measured ground loadings has 80 % of particles Φ ≥ 4 that aggregate uniformly in the range Φ = −1 to 3. Two additional simulations of a VS event were carried out by using meteorological data of two specific periods to exemplify weather's potential on impacts of such eruptions, particularly tephra loading, on the surrounding areas. The model outcomes clearly highlight the major effects of differences in local meteorology on plume dynamics and ash dispersal and the key role of wind shear in determining the cumulative thickness of ground deposits. Results also show that, due to the long duration of this kind of eruption and the large variability in zonal winds at this latitude, ash dispersal and fallout from VS events at Vesuvius represent a probable hazard for all of the territory near Vesuvius, including the city of Naples, where cumulative tephra loadings might reach critical thresholds for roof collapse and infrastructure damage. [ABSTRACT FROM AUTHOR]

The Pleistocene Lake Purrumbete maar eruption sequence of the Newer Volcanics Province of southeastern Australia records stratigraphic, temporal and geochemical variations that cannot be explained by crustal processes, such as fractional crystallisation and crustal contamination. Samples from the Lake Purrumbete maar have distinct trace element trends that correlate with stratigraphic height, with decreasing incompatible element concentrations from the bottom of the sequence to the top, indicating that the most enriched melts were ejected during the earliest eruption stages, with the least enriched melts erupted in the final stages. Variations in rare earth element ratios indicate that these melts were formed by dynamic melting of garnet lherzolite mantle material, consistent with other volcanic centres within the basaltic cones subprovince of the Newer Volcanics Province. The geochemistry of the erupted units at Lake Purrumbete also record minor differentiation of the melts by olivine fractionation, although these processes alone cannot explain the observed geochemical variations in the eruption sequence. Further differentiation of the melts by different processes such as deep clinopyroxene fractionation or assimilation of metasomatised lithosphere may be responsible for the observed geochemical trends at Lake Purrumbete. This shows the complexity of the plumbing system of monogenetic volcanoes, but also shows the opportunities that these volcanoes provide to study these processes in detail, as the geochemical variations that are preserved in this type of volcanism by fast magma ascent through the crust, as evidenced by the presence of fresh mantle xenoliths, predominantly reflect processes that occurred in the mantle rather than in the crust. [ABSTRACT FROM AUTHOR]

In 2012 Plummer et al., in presenting the volcanic chronology of the Antarctic Law Dome ice core, chose to list connections to acid layers in other ice cores and also possible chronological coincidences between ice acid dates and the precise dates of frost damage, and/or reduced growth in North American bristlecone pines. We disagree with the chronological links indicated by Plummer et al. for the period before AD 700, and in this paper we show that a case can be made that better linkages between ice acid and tree ring effects occur for this period if the ice chronologies are systematically moved forward by around 7 years, consistent with a hypothesis published by Baillie in 2008. In the paper we seek to explore the proposition that frost damage rings in North American bristlecone pines are a very useful indicator of the dates of certain large explosive volcanic eruptions; the dating of major eruptions being critical for any clear understanding of volcanic forcing. This paper cannot prove that there is an error in the Greenland Ice Core Chronology 2005 (GICC05), and in equivalent ice chronologies from the Antarctic, however, it does provide a coherent argument for an apparent ice dating offset. If the suggested offset were to prove correct it would be necessary to locate where the error occurs in the ice chronologies and in this regard the dating of the increasingly controversial Icelandic Eldgjá eruption in the AD 930s, and the China/Korean Millennium eruption which occurs some 7 years after Eldgjá, may well be critical. In addition, if the offset were to be substantiated it would have implications for the alleged identification of tephra at 429.3m in the Greenland GRIP core, currently attributed to the Italian volcano Vesuvius and used as a critical zero error point in the GICC05 chronology. [ABSTRACT FROM AUTHOR]

X-ray photoelectron spectroscopy has been employed for the chemical characterization of the surface of volcanic ashes erupted by Mt Etna during the 2013 activity. The data, coupled with bulk mineralogical and chemical analysis, showed the strong F and S enrichment and the depletion on Si, Ca, Na and K of the nanometric external shell. The surface chemical modification may be ascribed to the interaction in the eruptive plume of volcanic particles, mainly formed by glass, and volcanic gasses. The processes of dissolution caused by acid compounds are responsible of the depletion of alkaline and alkaline earth elements followed by the deposition on the surface of strongly soluble sulphate and fluoride as pointed out by the further depletion of these elements after leaching experiments. The presence in the plume of HF may cause the formation of volatile SiF4 and determine the consequent low Si abundance in the particle surface. [ABSTRACT FROM AUTHOR]

Volcanic ash layers preserved within the geologic record represent precise time markers that correlate disparate depositional environments and enable the investigation of synchronous and/or asynchronous behaviors in Earth system and archaeological sciences. However, it is generally assumed that only exceptionally powerful events, such as supereruptions (≥450 km³ of ejecta as dense-rock equivalent; recurrence interval of ~105 yr), distribute ash broadly enough to have an impact on human society, or allow us to address geologic, climatic, and cultural questions on an intercontinental scale. Here we use geochemical, age, and morphological evidence to show that the Alaskan White River Ash (eastern lobe; A.D. 833-850) correlates to the "AD860B" ash (A.D. 846-848) found in Greenland and northern Europe. These occurrences represent the distribution of an ash over 7000 km, linking marine, terrestrial, and ice-core records. Our results indicate that tephra from more moderate-size eruptions, with recurrence intervals of ~100 yr, can have substantially greater distributions than previously thought, with direct implications for volcanic dispersal studies, correlation of widely distributed proxy records, and volcanic hazard assessment. [ABSTRACT FROM AUTHOR]

On October 17, 1891, a submarine eruption started at Foerstner volcano located within the Pantelleria Rift of the Strait of Sicily (Italy). Activity occurred for a period of 1 week from an eruptive vent located 4 km northwest of the island of Pantelleria at a water depth of 250 m. The eruption produced lava balloons that discharged gas at the surface and eventually sank to the seafloor. Remotely operated vehicle (ROV) video footage and high-resolution multi-beam mapping of the Foerstner vent site were used to create a geologic map of the AD 1891 deposits and conduct the first detailed study of the source area associated with this unusual type of submarine volcanism. The main Foerstner vent consists of two overlapping circular mounds with a total volume of 6.3 × 10 m and relief of 60 m. It is dominantly constructed of clastic scoriaceous deposits with some interbedded pillow lavas. Petrographic and geochemical analyses of Foerstner samples by X-ray fluorescence and inductively coupled plasma mass spectrometry reveal that the majority of the deposits are vesicular, hypocrystalline basanite scoria that display porphyritic, hyaloophitic, and vitrophyric textures. An intact lava balloon recovered from the seafloor consists of a large interior gas cavity surrounded by a thin lava shell comprising two distinct layers: a thin, oxidized, quenched crust surrounding the exterior of the balloon and a dark gray, tachylite layer lying beneath it. Ostwald ripening is proposed to be the dominant bubble growth mechanism of four representative Foerstner scoria samples as inferred by vesicle size distributions. Characterization of the diversity of deposit facies observed at Foerstner in conjunction with quantitative rock texture analysis indicates that submarine Strombolian-like activity is the most likely mechanism for the formation of lava balloons. The deposit facies observed at the main Foerstner vent are very similar to those produced by other known submarine Strombolian eruptions (short pillow flow lobes, large scoriaceous clasts, spatter-like vent facies). Balloons were likely formed from the rapid cooling of extremely vesicular magma fragments as a result of a gas-rich frothy magma source. The exterior of these fragments hyperquenched forming a vesicular glassy shell that acted as an insulating layer preventing magmatic gas in its interior from escaping and thus allowing flotation as densities reached less than 1,000 kg/m. We believe that lava balloons are a common eruptive product, as the conditions required to generate these products are likely to be present in a variety of submarine volcanic environments. Additionally, the facies relationships observed at Foerstner may be used as a paleoenvironmental indicator for modern and ancient basaltic shallow submarine eruptions because of the relatively narrow depth range over which they likely occur (200-400 m). [ABSTRACT FROM AUTHOR]

The persistent activity of Yasur volcano, a post-caldera scoria cone in the southern Vanuatu Arc, along with the uniformity exhibited by its eruptive products, indicates that it is a 'steady-state' volcano. This implies that rates of magma replenishment and tapping are in equilibrium. Examination of recently exposed tephra sequences suggests that Strombolian-style activity at Yasur has persisted in its current form for the last 630-850 years. Eruption of tephra with uniform grain size and texture throughout this period indicates invariant eruption magnitude and style. Based on tephra accumulation rates, a uniform, time-averaged eruption flux of ∼410-480 m days is estimated. Major and trace element analyses of glass shards and mineral grains from these tephra deposits show limited variation in magma composition throughout that time, consistent with a chemically buffered magma reservoir and models for steady-state volcanism. Similarly, mineral crystallisation temperature estimates are within error, suggesting the magma reservoir has retained a constant temperature through this time, while pressure estimates suggest shallow crystallisation. Eruptions appear to be driven by gas release, with small fluctuations in magma chemistry and eruptive behaviour governed by perturbations in volatile flux. This period of steady-state activity was preceded by ∼600 years of higher-magnitude, lower-frequency eruptions during which less evolved compositions were erupted. Variation between these two styles of eruptive behaviour may be explained by a shift from a periodically closed to fully opened conduit, allowing more regular magma release and changes to degassing regimes. New radiocarbon ages suggest a period of irregular eruptive behaviour extending >1,400 year B.P. Overall, a transition from an irregular to a very steady magmatic system has occurred over the past ∼2 kyr. Previously determined tectonic indicators for caldera resurgence in the area suggest revived magma replenishment after a hiatus following the caldera-forming Siwi eruption. This replenishment, while now supplying today's constant activity, has not yet manifested itself in variations in composition or style/magnitude of eruptions. [ABSTRACT FROM AUTHOR]

Stromboli is known for its mild, persistent explosive activity from the vents located within the summit crater depression at the uppermost part of the Sciara del Fuoco (SdF) depression. Effusive activity (lava flows) at this volcano normally occurs every 5-15 years, involving often the opening of eruptive fissures along the SdF, and more rarely overflows from the summit crater. Between the end of the 2007 effusive eruption and December 2012, the number of lava flows inside and outside the crater depression has increased significantly, reaching a total of 28, with an average of 4.8 episodes per year. An open question is why this activity has become so frequent during the last 6 years and was quite rare before. In this paper, we describe this exceptional activity and propose an interpretation based on the structural state of the volcano, changed after the 2002-2003 and even more after the 2007 flank effusive eruption. We use images from the Stromboli fixed cameras network, as well as ground photos, plume SO and CO fluxes released by the summit crater, and continuous fumarole temperature recording, to unravel the interplay between magma supply, structural and morphology changes, and lava flow output. Our results might help forecast the future behaviour and hazard at Stromboli and might be applicable to other open-conduit volcanoes. [ABSTRACT FROM AUTHOR]

This study focuses on the Holocene Neostromboli lava cone which is part of the Stromboli volcano (Aeolian Islands, Italy). It represents an important example of the structure and behaviour of lava cone re-growth shortly after a large-scale volcano sector collapse. Neostromboli's eruptive style is dominated by extrusion of sheet-like a'a lava flows and associated autoclastic breccias. The lava cone developed during five phases of activity (phases A to E) representing discrete episodes of lava effusion characterised by rapid changes in magma composition, spatial development of the feeder system and physical properties of erupted lavas through time. Although they all belong to the potassic series (KS) with SiO 49-55 wt% and MgO 2.50-6.25 wt%, the Neostromboli lavas have distinct petrogenetic characteristics ranging from leucite-free and low-Sr shoshonitic basalts (phases A and B) to leucite-bearing shoshonitic basalts with high (phase C) and intermediate (phase D) Sr contents, and to leucite-free, biotite-bearing shoshonites (phase E). Three different batches of mantle-derived, relatively primitive basic magmas fed the activity of phases A, C and D. The evolution phases A to B is inferred to have occurred in a continuously replenished, tapped and crystallizing (RTF) magma chamber whereas phase E products were dominantly generated by fractional crystallization from phase D magmas. The Neostromboli cone shows summit, flank and satellite vents and sheet intrusions with different geometry and location through time, reflecting the interplay of regional tectonics, precursory instability processes and volcano load. [ABSTRACT FROM AUTHOR]

Abstract: The ice-capped Cotopaxi volcano is known worldwide for the large-scale, catastrophic lahars that have occurred in connection with historical explosive eruptions. The most recent large-scale lahar event occurred in 1877 when scoria flows partially melted ice and snow of the summit glacier, generating debris flows that severely impacted all the river valleys originating from the volcano. The 1877 lahars have been considered in the recent years as a maximum expected event to define the hazard associated to lahar generation at Cotopaxi. Conversely, recent field-based studies have shown that such debris flows have occurred several times during the last 800years of activity at Cotopaxi, and that the scale of lahars has been variable, including events much larger than that of 1877. Despite a rapid retreat of the summit ice cap over the past century, in fact, there are no data clearly suggesting that future events will be smaller than those observed in the deposits of the last 800years of activity. In addition, geological field data prove that the lahar triggering mechanism also has to be considered as a key input parameter and, under appropriate eruptive mechanisms, a hazard scenario of a lahar with a volume 3-times larger than the 1877 event is likely. In order to analyze the impact scenarios in the southern drainage system of the volcano, simulations of inundation areas were performed with a semi-empirical model (LAHARZ), using input parameters including variable water volume. Results indicate that a lahar 3-times larger than the 1877 event would invade much wider areas than those flooded by the 1877 lahars along the southern valley system, eventually impacting highly-urbanized areas such as the city of Latacunga. [Copyright &y& Elsevier]

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Improving lava flow hazard assessment is one of the most important and challenging fields of volcanology, and has an immediate and practical impact on society. Here, we present a methodology for the quantitative assessment of lava flow hazards based on a combination of field data, numerical simulations and probability analyses. With the extensive data available on historic eruptions of Mt. Etna, going back over 2000 years, it has been possible to construct two hazard maps, one for flank and the other for summit eruptions, allowing a quantitative analysis of the most likely future courses of lava flows. The effective use of hazard maps of Etna may help in minimizing the damage from volcanic eruptions through correct land use in densely urbanized area with a population of almost one million people. Although this study was conducted on Mt. Etna, the approach used is designed to be applicable to other volcanic areas. [ABSTRACT FROM AUTHOR]