Icelandic Volcano Research Articles

Study of the impact of ash fallout from the Icelandic volcano Eyjafjöll (2010) on vegetation using MODIS data

Study of the impact of ash fallout from the Icelandic volcano Eyjafjöll (2010) on vegetation using MODIS data

Phytoplanktonic response to simulated volcanic and desert dust deposition events in the South Indian and Southern Oceans

AbstractContrasting concentrations of macronutrients and micronutrients induce different nutrient limitations of the oceanic productivity and shape the composition of the phytoplankton communities of the South Indian Ocean and Indian sector of the Southern Ocean. o assess the phytoplankton response to nutrient release by desert dust and volcanic ash aerosols in these distinct biogeochemical regions, we conducted microcosm incubation experiments. A dry or wet deposition of either dust from Patagonia or ash from the Icelandic volcano Eyjafjallajökull or dissolved nutrients (Si, Fe, N and/or P) were added to trace metal clean incubations of surface seawater collected from five stations. These deposition experiments enabled the measurement of the biological response along with solubility calculations of nutrients. Both types of aerosols alleviated the iron deficiency occurring in the Southern Ocean during austral summer and resulted in a 24–110% enhancement of the primary production, depending on the station. The release of dissolved silicon may also have contributed to this response, although to a lesser extent, whereas neither the dust nor the ash relieved the nitrogen limitation in the low‐nutrient and low‐chlorophyll area. Diatom growth was responsible for 40% to 100% of the algal biomass increase within the responding stations, depending on the region and aerosol type. The high particle concentrations that are characteristic of ash deposition following volcanic eruptions may be of equal or higher importance to phytoplankton compared to desert dust, despite ashes' lower nutrient solubility to the ocean.

Spatial distribution and geochemical characterization of Icelandic mantle end-members: Implications for plume geometry and melting processes

We compile a new geochemical database (Icelandic Volcanic rocks Isotopic Database, IVID) which includes previously reported 87Sr/86Sr, 143Nd/144Nd, 176Hf/177Hf, 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb, 187Os/188Os and 3He/4He data and major and trace element concentrations measured in Icelandic volcanic rocks. Isotopic compositions were evaluated and filtered to identify the highest quality data and data most likely to represent mantle-derived compositions. The carefully filtered, comprehensive geochemical database is an important contribution to the geochemical community and can be used to put further constraints on the generation of geochemical heterogeneity in Iceland. We use the compiled database to examine the spatial distribution of geochemical components in the Icelandic mantle, and test whether melting processes control how source heterogeneity from the deep mantle is extracted on the surface. The PRIMELT software (which combines an inverse model for crystallization in the crust with a forward model of mantle melting to estimate the primary mantle-derived magma composition) is used to estimate mantle potential temperatures and melt fractions in Iceland. The results of these calculations and forward melting models demonstrate that mantle potential temperatures have a largely insignificant role, and that lithospheric thickness plays a key role in generating geochemical heterogeneity in Icelandic volcanic rocks. Volcanic rocks from the off-rift volcanic zones are generally produced by lower melt fractions, consistent with preferential sampling of geochemically enriched and fertile “blobs” at lower degrees of melting, where the lithosphere is thicker; more geochemically depleted volcanic rocks from the axial rift zones, where the lithosphere is thinner, show higher degrees of melting, consistent with dilution of enriched blob melts by melts of more depleted and refractory mantle.

Physics of Melt Extraction from the Mantle: Speed and Style

Melt extraction from the partially molten mantle is among the fundamental processes shaping the solid Earth today and over geological time. A diversity of properties and mechanisms contribute to the physics of melt extraction. We review progress of the past ∼25 years of research in this area, with a focus on understanding the speed and style of buoyancy-driven melt extraction. Observations of U-series disequilibria in young lavas and the surge of deglacial volcanism in Iceland suggest this speed is rapid compared to that predicted by the null hypothesis of diffuse porous flow. The discrepancy indicates that the style of extraction is channelized. We discuss how channelization is sensitive to mechanical and thermochemical properties and feedbacks, and to asthenospheric heterogeneity. We review the grain-scale physics that underpins these properties and hence determines the physical behavior at much larger scales. We then discuss how the speed of melt extraction is crucial to predicting the magmatic response to glacial and sea-level variations. Finally, we assess the frontier of current research and identify areas where significant advances are expected over the next 25 years. In particular, we highlight the coupling of melt extraction with more realistic models of mantle thermochemistry and rheological properties. This coupling will be crucial in understanding complex settings such as subduction zones. ▪ Mantle melt extraction shapes Earth today and over geological time. ▪ Observations, lab experiments, and theory indicate that melt ascends through the mantle at speeds ∼30 m/year by reactively channelized porous flow. ▪ Variations in sea level and glacial ice loading can cause significant changes in melt supply to submarine and subaerial volcanoes. ▪ Fluid-driven fracture is important in the lithosphere and, perhaps, in the mantle wedge of subduction zones, but remains a challenge to model.

The Origin of Tree‐Ring Reconstructed Summer Cooling in Northern Europe During the 18th Century Eruption of Laki

AbstractBasaltic fissure eruptions, which are characteristic of Icelandic volcanism, are extremely hazardous due to the large quantities of gases and aerosols they release into the atmosphere. The 1783–1784 CE Laki eruption was one of the most significant high‐latitude eruptions in the last millennium and had substantial environmental and climatic impacts. Contemporary observations recorded the presence of a sulfuric haze over Iceland and Europe, which caused famine from vegetation damage and resulted in a high occurrence of respiratory illnesses and related mortality. Historical records in northern Europe show that the summer of 1783 was anomalously warm, but regional tree‐ring maximum latewood density (MXD) data from that year are low and lead to erroneously colder reconstructed summer temperatures. Here, we measure wood anatomical characteristics of Scots pine (Pinus sylvestris) from Jämtland, Sweden in order to identify the cause of this discrepancy. We show that the presence of intraannual density fluctuations in the majority of 1783 growth rings, a sudden reduction in lumen and cell wall area, and the measurement resolution of traditional X‐ray densitometry led to the observed reduced annual MXD value. Multiple independent lines of evidence suggest these anatomical anomalies were most likely the result of direct acidic damage to trees in Northern Europe and that the normal relationship between summer temperature and MXD can be disrupted by this damage. Our study also demonstrates that quantitative wood anatomy offers a high‐resolution approach to identifying anomalous years and extreme events in the tree‐ring record.

New eruption at Fagradalsfjall Volcano follows days of seismic swarms

After a weekend of intense earthquakes, a spectacular new eruption at Fagradalsfjall volcano in Iceland began Wednesday afternoon. Volcano scientists are keeping a close eye on this eruption, but only time will tell what will happen.

Stratigraphic reconstruction of the Víti breccia at Krafla volcano (Iceland): insights into pre-eruptive conditions priming explosive eruptions in geothermal areas

Krafla central volcano in Iceland has experienced numerous basaltic fissure eruptions through its history, the most recent examples being the Mývatn (1724‒1729) and Krafla Fires (1975–1984). The Mývatn Fires opened with a steam-driven eruption that produced the Víti crater. A magmatic intrusion has been inferred as the trigger perturbing the geothermal field hosting Víti, but the cause(s) of the explosive response remain uncertain. Here, we present a detailed stratigraphic reconstruction of the breccia erupted from Víti crater, characterize the lithologies involved in the explosions, reconstruct the pre-eruptive setting, fingerprint the eruption trigger and source depth, and reveal the eruption mechanisms. Our results suggest that the Víti eruption can be classified as a magmatic-hydrothermal type and that it was a complex event with three eruption phases. The injection of rhyolite below a pre-existing convecting hydrothermal system likely triggered the Víti eruption. Heating and pressurization of shallow geothermal fluid initiated disruption of a scoria cone “cap” via an initial series of small explosions involving a pre-existing altered weak zone, with ejection of fragments from at least 60-m depth. This event was superseded by larger, broader, and dominantly shallow explosions (~ 200 m depth) driven by decompression of hydrothermal fluids within highly porous, poorly compacted tuffaceous hyaloclastite. This second phase was triggered when pressurized fluids broke through the scoria cone complex “cap”. At the same time, deep-rooted explosions (~ 1-km depth) began to feed the eruption with large inputs of fragmented rhyolitic juvenile and host rock from a deeper zone. Shallow explosions enlarging the crater dominated the final phase. Our results indicate that at Krafla, as in similar geological contexts, shallow and thin hyaloclastite sequences hosting hot geothermal fluids and capped by low-permeability lithologies (e.g. altered scoria cone complex and/or massive, thick lava flow sequence) are susceptible to explosive failure in the case of shallow magmatic intrusion(s).

Volcanic controls on the microbial habitability of Mars-analogue hydrothermal environments.

Due to their potential to support chemolithotrophic life, relic hydrothermal systems on Mars are a key target for astrobiological exploration. We analysed water and sediments at six geothermal pools from the rhyolitic Kerlingarfjöll and basaltic Kverkfjöll volcanoes in Iceland, to investigate the localised controls on the habitability of these systems in terms of microbial community function. Our results show that host lithology plays a minor role in pool geochemistry and authigenic mineralogy, with the system geochemistry primarily controlled by deep volcanic processes. We find that by dictating pool water pH and redox conditions, deep volcanic processes are the primary control on microbial community structure and function, with water input from the proximal glacier acting as a secondary control by regulating pool temperatures. Kerlingarfjöll pools have reduced, circum-neutral CO2 -rich waters with authigenic calcite-, pyrite- and kaolinite-bearing sediments. The dominant metabolisms inferred from community profiles obtained by 16S rRNA gene sequencing are methanogenesis, respiration of sulphate and sulphur (S0 ) oxidation. In contrast, Kverkfjöll pools have oxidised, acidic (pH<3) waters with high concentrations of SO42- and high argillic alteration, resulting in Al-phyllosilicate-rich sediments. The prevailing metabolisms here are iron oxidation, sulphur oxidation and nitrification. Where analogous ice-fed hydrothermal systems existed on early Mars, similar volcanic processes would likely have controlled localised metabolic potential and thus habitability. Moreover, such systems offer several habitability advantages, including a localised source of metabolic redox pairs for chemolithotrophic microorganisms and accessible trace metals. Similar pools could have provided transient environments for life on Mars; when paired with surface or near-surface ice, these habitability niches could have persisted into the Amazonian. Additionally, they offer a confined site for biosignature formation and deposition that lends itself well to in situ robotic exploration.

Conditions and Dynamics of Magma Storage in the Snæfellsnes Volcanic Zone, Western Iceland: Insights from the Búðahraun and Berserkjahraun Eruptions

AbstractEstablishing the conditions and dynamics of pre-eruptive magma storage and transfer within transient transcrustal storage networks is a major focus of quantitative volcanic petrology. In Iceland, the behaviour, conditions and timescales of magmatic processes within on-rift plumbing systems are increasingly well constrained. However, relatively little is known about magma storage and transfer in off-rift zones, despite off-rift volcanoes being able to generate hazardous explosive eruptions after centuries or millennia of dormancy (e.g. 2010 AD Eyjafjallajökull; 1362 AD Öræfajökull; 3.0 ka, 4.2 ka and 1104 AD Hekla). We present a combined geochemical and geothermobarometric study of magma storage and transfer recorded in the products of the postglacial Búðahraun (∼5.0–8.0 ka) and Berserkjahraun (∼4.0 ka) eruptions within the Snæfellsnes volcanic zone. The eruption products contain diverse and compositionally heterogeneous macrocryst cargoes recording complex petrogenetic histories of crystal evolution and inheritance from different parts of the sub-volcanic plumbing systems. Geothermobarometry indicates two compositionally and thermally heterogeneous magma storage regions located in the lower (20 ± 4 km) and upper-mid (11 ± 3 km) crust. Crystallization pressure and depth estimates coincide with comparable data from Vatnafell, a small sub-glacial table mountain (tuya) in the centre of the Snæfellsnes volcanic zone, indicating that the nature and conditions of magma storage have remained unchanged since the Upper Pleistocene. Trace element zoning of clinopyroxene macrocrysts indicates that mafic recharge into the upper-mid-crustal storage zone triggered the eruptions of Búðahraun and Berserkjahraun. Evidence for eruption-triggering mafic recharge and basaltic cannibalism involving the transfer and amalgamation of crystals with different evolutionary histories sets the Búðahraun and Berserkjahraun eruptions apart from other studied eruptions in Iceland. We propose that the compositional and textural diversity preserved within the crystal cargoes are a direct consequence of the reduced heat flow beneath the Snæfellsnes volcanic zone, which favours the formation of isolated melt pockets in which compositionally diverse macrocryst populations formed. Periodic flushes of primitive basaltic magma from depth promote widespread mixing with evolved melts, resulting in the assembly of crystals with diverse ancestries from different parts of the sub-volcanic systems. Insights gained from the diverse macrocryst cargoes of Búðahraun and Berserkjahraun and comparisons with recent off-rift volcanism in Iceland are essential for the development of future monitoring efforts and hazard evaluation. Although volcanism within the Snæfellsnes volcanic zone differs fundamentally from that in rift zones where eruptions are controlled by extensional spreading, magma ascent from depth still appears to follow pre-existing tectonic escape routes. This could result in extremely short advance warning times on the order of a few days.

Eruptive style controls the formation of silicon hexafluoride salts on volcanic ash: The case of the 2010 eruption of Eyjafjallajökull volcano, Iceland

The presence of fluoride (F−)-bearing compounds in volcanic ash fallout is recognised to pose significant environmental and health hazards. Nevertheless, understanding of the formation and composition of these compounds remains limited, or even inconsistent. This hampers full comprehension of the risks and impacts elicited by fluorine-rich ash emissions after an explosive eruption. The 2010 activity of Eyjafjallajökull volcano in Iceland was characterised by contrasted eruptive styles - phreatomagmatic and magmatic - which produced ash deposits with distinct soluble F− contents. Based on X-ray photoelectron spectroscopy and leachate analyses of Eyjafjallajökull ash materials, we infer the existence of silicon hexafluoride salts, particularly Na2SiF6, dominantly if not exclusively on the magmatic ash, and suggest a reaction mechanism for their formation. The presence of Na2SiF6 explains the much greater F− concentration and higher acidity measured in leachates of the magmatic ash compared to those of the phreatomagmatic ash. River waters affected by ash deposition during the magmatic activity showed a temporary increase in F− and decrease in dissolved silicon isotope values (δ30Si). We contend that the formation of silicon hexafluoride salts on ash leads to a surface enrichment of the ash's silicate glass and mineral components in 28Si, with the release of this light Si from the magmatic ash during the early stage of weathering causing a depression in the riverine δ30Si. This supports existing evidence of silicate dissolution processes being influenced by the presence of fluorine. Our study also points to the likely important role of Na2SiF6 in modulating the environmental and health effects of ash emissions from fluorine-rich magmatic eruptions.

The End of Closed Airspace in the Middle East: A Final Move on the Regional Chess Board?

Closure of airspace has become a new topic on the aviation agenda of the twenty-first century. States adopted this measure to begin with on 11 September 2002. The US closed its airspace for about five days after the occurrence of this tragedy in New York for all air traffic. European States did the same after the eruption of the Icelandic volcano Eyjafjallajökull in 2010. Pakistan shut its airspace in February 2019 after India carried out an air strike against a presumably terrorist training camp in Pakistani territory. While the above measures could be labelled as ‘incidental’ in terms of time period, the closures of airspace implemented in the second half of the second decade of this century are more ‘systematic’. They last longer and have a deeper background. Reference is made to the closure of airspace in the Middle East, and in practically all States following the outbreak of the Coronavirus disease 2019 (COVID-19) pandemic. This brief paper will focus on the closure of airspace in the Middle East, which came to an end in January 2020, and pay attention to the regulatory proceedings surrounding it. These can only be understood against the wider political, historical and perhaps also religious background. Those factors contribute to the fragility of the legal arrangements underpinning the diplomatic deal. closure of airspace, sovereignty and territorial jurisdiction, non-discrimination, air traffic services, compensation of damages

A microanalytical oxygen isotopic and U-Th geochronologic investigation and modeling of rhyolite petrogenesis at the Krafla Central Volcano, Iceland

Understanding the petrogenesis of silicic magmas is critical for understanding the volcanic hazards they pose, their geothermal energy potential, and the creation of continental crust. In this study we explore the origin of rhyolitic magmas in basaltic crust at the Krafla Central Volcano in Iceland. We present laser fluorination oxygen isotope analyses of plagioclase, pyroxene, and groundmass from eight rhyolites and six selected basalts, as well as in situ oxygen isotope analyses and U-Th geochronology of zircons from three rhyolitic domes erupted around the caldera margins. Zircon U-Th geochronology for the rhyolite domes yields ages of 88.7 ± 9.9 ka for Jörundur, 83.3 ± 9.2 ka for Hlíðarfjall, and 85.5 ± 9.4 ka for Gæsafjallarani, some 20–30 ka after the eruption of the zoned rhyolite to basalt Halarauður ignimbrite during a major collapse of the Krafla caldera. We suggest that the domes represent a renewed episode of silicic magma production in the pre-heated crust. Oxygen isotope analyses of single and bulk plagioclase and pyroxene identify some instances of isotopic disequilibrium with groundmass (~3.5‰) reflecting assimilation of diverse low δ18O crustal material. However, zircon is largely in equilibrium with groundmass analyses, suggesting it crystallized directly from low δ18O magma. Zircon trace elements (Hf, Yb, Th, U) for all three domes show trends indicative of fractional crystallization. Pairing these observations with two-dimensional thermal modeling using the Heat2D model, and chemical modeling using the Magma Chamber Simulator, we suggest that petrogenesis of rhyolitic magma at Krafla requires at least two-steps: the δ18O of basaltic parental magmas are first lowered through assimilation of hydrothermally altered material (generated in the high temperature region in the crust surrounding the magma chamber) to produce low δ18O mafic to intermediate magmas, which then ascend from magma generation zones into colder crust where they undergo further fractional crystallization at shallower depths. Our models suggest that prior hydrothermal alteration of the mafic crust greatly increases the volume of partial melt that can be produced and assimilated, and we thus suggest that long-lived hydrothermal systems may play an important role in further encouraging the production of larger volumes of rhyolitic magmas in basalt-dominated environments.

Particulate iron and other trace elements in near-surface waters of the high latitude North Atlantic following the 2010 Eyjafjallajökull eruption

In situ pumps were used to collect size-fractionated particles (>53 μm and 1–53 μm) from the upper ocean of the high latitude North Atlantic during spring and summer 2010, and samples were subsequently analysed for Al, P, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Cd, Ba and Pb. Two research cruises during May 2010 coincided with an eruption of the Eyjafjallajökull volcano in southern Iceland, which resulted in widespread dispersal of ash over the region. Ash deposition caused a noticeable perturbation of particulate trace element concentrations and content within marine particles in the Iceland Basin, relative to the Irminger Basin, most evident for lithogenic elements (Al, Ti, Fe), but also noticeable in elemental ratios for the other elements. The initial volcanic ash influence had largely disappeared by the third research cruise in July/August 2010, although there was evidence for a recent wind erosion event having transported remobilized volcanic ash from southern Iceland to the northern Iceland Basin in early July, further perturbing local trace element biogeochemistry. During summer 2010, concentrations of all measured elements except Ba were typically lower 10 m beneath the surface mixed layer relative to those within it, driven primarily by a rapid decrease in the concentrations of large (>53 μm) biogenic particles. Depth-dependent trends were more variable over the next hundred metres for all elements except the biogenic elements P and Cd, for which concentrations decreased further. The continued loss of biogenic material with depth due to remineralization (reflected by particulate P concentrations) led to an increase in content per mass of material for all other elements measured. The observed differences in upper ocean particulate P and Fe distributions highlight the mechanism driving seasonal Fe limitation in the high latitude North Atlantic: rapid loss of P by remineralization regenerates dissolved phosphate close to the base of the mixed layer, while most particulate Fe persists deeper in the water column, removing the potential for resupply of dissolved Fe to surface waters.

Magmatic Processes at Snæfell Volcano, Iceland, Constrained by Zircon Ages, Isotopes, and Trace Elements

AbstractWe present the first zircon‐based U‐Pb geochronology, trace element concentrations, and O and Hf isotope compositions for Snæfell, an off‐rift volcano in eastern Iceland. These data provide constraints on the longevity and petrogenetic conditions of the Snæfell magmatic system. U‐Pb zircon ages range from 545 ± 59 to 266 ± 16 ka (2SE), but differences between grain core and mantle ages within each sample reveal zircon residence times of 100–200 kyr—far longer than observed at other Neovolcanic systems in Iceland. Zircon δ18O is restricted to ∼3.5–4‰, and zircon εHf ranges ∼+13 to ∼+17, which is substantially more radiogenic than Snæfell basalts. This combined O and Hf isotopic perspective suggests rhyolite petrogenesis at Snæfell can be attributed to fractional crystallization of mantle‐derived basaltic magmas with limited influence of pre‐existing crustal material. Trace element evidence further characterizes the magmatic source material: Sc/Yb &lt;∼0.01 suggests an amphibole‐free petrogenetic environment, and Ti concentrations in zircon &lt;5 ppm suggest a cool, near‐solidus, crystallization environment for the majority of the zircon's pre‐eruptive history, with elevated Ti in zircon surfaces suggesting a late thermal perturbation, perhaps a mafic input that remobilized (to the point of eruption triggering) near‐solidus magmas. These zircon‐based conclusions are broadly consistent with previous interpretations of rhyolite petrogenesis conditions at Snæfell but provide a multi‐faceted perspective with more detailed resolution of source materials, magma generating processes, system longevity, and pre‐eruptive conditions.

Ritual responses to catastrophic volcanism in Viking Age Iceland: Reconsidering Surtshellir Cave through Bayesian analyses of AMS dates, tephrochronology, and texts

Surtshellir, a 1600-m-long lava cave in the interior of Iceland, contains a unique Viking Age archaeological site located nearly 300 m from its entrance and more than 10 m below the surface of the Hallmundarhraun lava field. Since the 1750s, the site has been interpreted as an outlaw shelter, yet in the 12th-13th centuries it was associated with actions directed towards an elemental being – Surtr – for whom the site was named and who, according to medieval Icelandic accounts of Viking Age mythology, was present at the world's creation and would destroy it after the battle of Ragnarök. Archaeological fieldwork inside Surtshellir in 2001, 2012, and 2013 produced 20 new AMS dates that, combined with three earlier radiocarbon and tephrochronological dates, provide the basis for Bayesian analyses which suggest (1) that the cave formed in the first major volcanic eruption directly witnessed by northern Europeans since the Late Pleistocene; (2) that this took place shortly after the Norse colonization of Iceland began; (3) that people entered the cave soon afterwards; (4) that for 80–120 years they deposited the fragmented bones of slaughtered domestic animals in piles stretching 120 m through the cave's “dark zone”, burning others at high temperatures in a dry-stone structure built deep inside a raised side passage; and (5) that these activities ended shortly after Iceland's conversion to Christianity. Surtshellir provides important new insights into Viking Age ritual practice, Iceland's settlement and conversion, and the cultural responses of Iceland's newly arrived settlers to the existential challenges posed by previously unimagined catastrophic volcanism.

Green Quadriga? - EU - Taxonomy, TCFD, Non-Financial-Reporting Directive and EBA ESG Pillar III/ IFRS Foundation

After years of inactivity, sustainability finance is erupted like the Iceland volcano Eyjafjallajökull. Several regulators have been proposing or are proposing new requirements on sustainability reporting, ESG metrics and standardization of ESG disclosures. The EU taxonomy issues by the EU commission, the task-force on climate-related disclosures, finance (TCFD), The European Banking Authority (EBA) launches consultation on Environmental, Social and Governance (ESG) risks as well as IFRS Foundation on sustainability reporting and the Non-Financial Reporting Directive also reflecting the European Green Dela (EGD). In order to meet the EU climate and energy targets for 2030 and reach the objectives of the European Green Deal, it is fundamental to direct investments towards sustainable projects and activities. The current COVID-19 pandemic has reinforced the need to redirect capital flows towards sustainable projects in order to make our economies, businesses and societies, in particular health systems, more resilient against climate and environmental shocks and risks with clear co-benefits for health. To achieve this, a common language and a clear definition of what is ‘sustainable’ is needed. This is why the action plan on financing sustainable growth called for the creation of a common classification system for sustainable economic activities, or an “EU taxonomy” the EU Commission Non-financial Reporting Update (NFRD) however issues which are material to environmental and social objectives can have financial material impact. The EU Taxonomy Regulation establishes six environmental objectives: Climate change mitigation, Climate change adaptation, the sustainable use and protection of water and marine resources, the transition to a circular economy and the pollution prevention and control. This research note assesses and comments deliverables from the EU commission.

P Wave Tomography Beneath Greenland and Surrounding Regions: 2. Lower Mantle

AbstractWe study the 3‐D P wave velocity (Vp) structure of the whole mantle beneath Greenland and surrounding regions using the latest P wave arrival time data. We use a new method of global seismic tomography by setting 3‐D grid nodes densely in the study volume to enhance the resolution. We invert ~5.6 million arrival times of P, pP, and PP waves from 16,257 earthquakes extracted from the ISC‐EHB catalog, which were recorded at 12,549 seismic stations in the world. Our results reveal a hot plume rising from the core‐mantle boundary beneath central Greenland, which is called the Greenland plume. This plume has the main conduit and two branches in the lower mantle, and the main conduit rises to the mantle transition zone (MTZ) beneath eastern Greenland, so it is distinguishable from the Iceland plume that appears to rise from a midmantle depth (~1,500 km) beneath Iceland. The Iceland plume itself is a powerful plume, but it may also be fed by hot mantle materials from three joints with other plumes: a branch of the Greenland plume at ~1,500 km depth, a plume beneath Western Europe at ~1,000 km depth, and the main conduit of the Greenland plume at the MTZ, leading to many active volcanoes in Iceland. We deem that the main conduit of the Greenland plume mixes with the Iceland plume incompletely and splits mainly into the Jan Mayen and Svalbard plumes in the upper mantle, which supply magma to the Jan Mayen hotspot and a geothermal area in western Svalbard, respectively.

Extension of the WRF-Chem volcanic emission preprocessor to integrate complex source terms and evaluation for different emission scenarios of the Grimsvötn 2011 eruption

Abstract. Volcanic eruptions may generate volcanic ash and sulfur dioxide (SO2) plumes with strong temporal and vertical variations. When simulating these changing volcanic plumes and the afar dispersion of emissions, it is important to provide the best available information on the temporal and vertical emission distribution during the eruption. The volcanic emission preprocessor of the chemical transport model WRF-Chem has been extended to allow the integration of detailed temporally and vertically resolved input data from volcanic eruptions. The new emission preprocessor is tested and evaluated for the eruption of the Grimsvötn volcano in Iceland 2011. The initial ash plumes of the Grimsvötn eruption differed significantly from the SO2 plumes, posing challenges to simulate plume dynamics within existing modelling environments: observations of the Grimsvötn plumes revealed strong vertical wind shear that led to different transport directions of the respective ash and SO2 clouds. Three source terms, each of them based on different assumptions and observational data, are applied in the model simulations. The emission scenarios range from (i) a simple approach, which assumes constant emission fluxes and a predefined vertical emission profile, to (ii) a more complex approach, which integrates temporarily varying observed plume-top heights and estimated emissions based on them, to (iii) the most complex method that calculates temporal and vertical variability of the emission fluxes based on satellite observations and inversion techniques. Comparisons between model results and independent observations from satellites, lidar, and surface air quality measurements reveal the best performance of the most complex source term.

Bunsen the Geochemist: Icelandic Volcanism, Geyser Theory, and Gas, Rock and Mineral Analyses.

Following the eruption of Hekla in 1845-1846 Bunsen was invited by King Christian VIII of Denmark and Iceland to participate in a geochemical expedition to Iceland together with the geologist Sartorius von Waltershausen and the physiologist Carl Bergmann from Göttingen. The French mineralogist Des Cloizeaux went to Iceland separately and joined the expedition. The eudiometer invented by Bunsen was crucial for his accurate characterization of volcanic gases and determination of the composition of mixtures. His analyses of the chemical compositions of numerous rocks and minerals led him to the classification of two fundamental rock types, the more silica rich (nowadays called felsic) and the less silica rich, more basic (mafic) in agreement with Des Cloizeaux and the Danish scientist J. C. Schythe. Bunsen also formulated the correct mechanism of geyser action and helped disband the theory of connections between geysers, volcanoes and the sea. He disagreed vehemently with Waltershausen over the mechanisms of formation of sal ammoniac and of volcanic rocks and their chemical compositions. He revealed himself as an ardent experimentalist vigorously opposed to hypotheses of any kind, which also made him dismiss the new chemical theories, for example, those of Dumas and Kekulé.

The Evolution of Icelandic Volcano Emissions, as Observed From Space in the Era of NASA's Earth Observing System (EOS)

AbstractVolcanoes are natural phenomena that have global environmental impacts. Satellite remote sensing can help classify volcanic eruptions and track the dispersion of emissions. We assess multiple volcanic eruptions in Iceland (Eyjafjallajökull 2010, Grímsvötn 2011, and Holuhraun 2014–2015), using space‐borne observations to infer information about the geological dynamics of each volcano and the properties and evolution of plume particles. We derive qualitative constraints on plume particle size, shape, and light‐absorption characteristics from Multiangle Imaging SpectroRadiometer (MISR) space‐borne imagery. With the MISR Research Algorithm (RA), we distinguish sulfate/water‐dominated volcanic plumes from Holuhraun and ash‐dominated plumes from Eyjafjallajökull and Grímsvötn, and even identify subtler changes in ash particle size and light‐absorption within plumes. Additionally, plume heights are retrieved geometrically from MISR. These are combined with surface thermal anomalies from the MODerate resolution Imaging Spectroradiometer (MODIS) and SO2 concentrations derived from the Ozone Monitoring Instrument (OMI) to synthesize eruption remote‐sensing chronologies. Signals related to differences in particle properties are identified and linked to evolving magma composition at Eyjafjallajökull. The results illustrate the potential to distinguish qualitative differences in eruptive magma composition based on particle light absorption and plume profile from remote‐sensing. For the sulfate‐rich Holuhraun plumes, the influence of aerosol hygroscopic growth during transport is inferred from such data. Three processes appear to dominate plume evolution in Iceland: downwind aerosol formation, particle hydration, and particle deposition. This work demonstrates enhanced MISR capabilities and, more generally, remote‐sensing analysis that can be applied globally, especially where suborbital volcano observations are limited or entirely absent.