Grimsvotn Research Articles

Atmospheric effects in Scotland of the AD 1783–84 Laki eruption in Iceland

Daily weather diaries and meteorological records from Scotland reveal complex weather patterns following the 1783–84 fissure eruption of the Laki volcano, Iceland. Four diarists in eastern and northern Scotland describe the near-simultaneous occurrence of discrete groups of days characterised by ‘foggy’, ‘gloomy’ and ‘hazy’ conditions during June and July 1783. The weather records suggest that an ash-rich portion of the initial plume may have arrived synchronously across eastern Scotland on June 15th, 5 days after the first eruption in Iceland, and lingered for between 5 and 7 days. Following a 3-day interval of fine weather, a sulphurous haze arrived on June 24th and persisted for the rest of the summer. As the summer progressed air pollution episodes became shorter, less frequent and more influenced by air pressure fluctuations. The effect of the eruption on Scotland’s climate is unclear although a negative air temperature anomaly of 1.5°C to 2.5°C below the decadal average occurred in September 1783 lasting for 16 days at Dalkeith and 33 days at Fochabers. The 1783–84 winter in Scotland was one of the coldest in recent centuries and was accompanied by prolonged snow and frost through the first 4 months of 1784. During this period, temperatures in eastern Scotland averaged 2.0°C to 2.6°C below the decadal average. The duration and amplitude of post-eruption negative temperature anomalies appear to have been strongly associated with synoptic air pressure and wind flow patterns and not simply related to volcanically-forced cooling. This challenges the hypothesis that the Laki eruptions were responsible for the sustained lowering of air temperatures over the three successive winters of 1783–84, 1784–85 and 1785–86.

Design of parametric risk transfer solutions for volcanic eruptions: an application to Japanese volcanoes

Abstract. Volcanic eruptions are rare but potentially catastrophic phenomena, affecting societies and economies through different pathways. The 2010 Eyjafjallajökull eruption in Iceland, a medium-sized ash-fall-producing eruption, caused losses in the range of billions of dollars, mainly to the aviation and tourism industries. Financial risk transfer mechanisms such as insurance are used by individuals, companies, governments, etc., to protect themselves from losses associated with natural catastrophes. In this work, we conceptualize and design a parametric risk transfer mechanism to offset losses to building structures arising from large, ash-fall-producing volcanic eruptions. Such a transfer mechanism relies on the objective measurement of physical characteristics of volcanic eruptions that are correlated with the size of resulting losses (in this case, height of the eruptive column and predominant direction of ash dispersal) in order to pre-determine payments to the risk cedent concerned. We apply this risk transfer mechanism to the case of Mount Fuji in Japan by considering a potential risk cedent such as a regional government interested in offsetting losses to dwellings in the heavily populated prefectures of Tokyo and Kanagawa. The simplicity in determining eruptive column height and ash fall dispersal direction makes this design suitable for extrapolation to other volcanic settings worldwide where significant ash-fall-producing eruptions may occur, provided these parameters are reported by an official, reputable agency and a suitable loss model is available for the volcanoes of interest.

Psychological impact of a volcano eruption − Mount Nyiragongo

The volcanic eruption is a rather uncommon type of natural disaster and is restricted to certain geographical regions. The psychological distress studied among the evacuees of a volcano in many countries revealed symptoms of anxiety, insomnia, anergia, social dysfunction, and anhedonia persisting even after six months of eruption. A study after a volcanic eruption in Iceland revealed higher incidence of mental distress and post-traumatic stress disorder (PTSD) in exposed versus the non-exposed groups. Insomnia, psychological morbidity, and possible long-term psychological morbidity were reported as the most common symptoms in the high-exposure group (based on the volcano-ash fall). Studies also show the involvement of children’s mental health. DRC, being a low-income country lacks the research and does not have strongly researched data regarding the prevalence of psychological morbidity post the volcano eruption. However, the psychological maladjustments after the Mount Nyiragongo eruption in 2002 were reported as the major health consequence as per WHO. This paper analyses the various psychological aspects during and after a volcanic eruption.

Generation of Spatial Profiles and Mapping of Volcanic Ash Distribution

Defining spatial distribution of airborne volcanic ash in the neighbourhood of an erupting volcano is a synoptic scale problem, severely impacting lives and livelihoods. Robust algorithms are needed to model such complex phenomenon from sparse field data. This study investigated optimal modelling of the spatial dispersion of ash using Empirical Bayesian Kriging (EBK): a geostatistical, probabilistic algorithm. Both distance and ash temperature values of samples from the 2010 Icelandic eruption were spatially correlated using semivariograms to generate prediction and error surfaces. Results showed that block averages were 90% accurate as validated against NCEP NWP model data. The work supports the utility of EBK in datasets where spatial autocorrelation is not significant. Furthermore, the results could help generate risk maps to delineate safety zones for aircrafts.

Ozonum—The Global Impact

AbstractThe remedy Ozonum has become the highest-ranking prescription in my practice during the coronavirus pandemic. Respiratory tract illnesses represent a smaller percentage of cases that have responded well to the remedy. Most cases I have seen were predominantly affected by the indirect impact of the pandemic. I have noticed a similar increase in Ozonum prescriptions following former global events, for example, the terrorist attack on the Twin Towers on 11th September 2001 in New York, the 2004 Indian Ocean earthquake and tsunami, the 2010 eruption of Iceland's Eyjafjallajökull volcano which paralysed flights across Europe and the severe 2017 to 2018 flu season. Ozone is a gas, called 'activated oxygen', formed by three atoms of oxygen instead of the two that we normally breathe. We are familiar with the protective function of the ozone layer in the atmosphere. The life cycle of ozone and its connection to ocean and marine life, to trees, habitat, and life in general, is less commonly known. A dynamic constellation of the homeopathic remedy becomes clear once we understand the ozone life cycle and its ecosystem in its natural and disrupted form. Ozonum—the homeopathic remedy—was used by our forefathers but has almost been forgotten until Anne Schadde's proving in nineties of the last century. Ozonum as a remedy has a wide range of applications such as pandemics, mass casualties and disasters, as well as routine clinical uses. Within different levels of context, the main feeling of Ozonum dynamic is exemplified by the statement—'I can't breathe!' It may be considered a 'polychrest' of our time evidently resonating with contemporary climatic, medical, socio-political and economic global challenges. We need to adopt a global view to keep up with the times and perceive a link between individual and global health in a broader perspective.

Detection of the historical Askja ad 1875 and modern Icelandic cryptotephras in varved lake sediments – results from a first systematic search in northern Poland

ABSTRACTVolcanic ash can disperse thousands of kilometres from the source volcano and provide valuable chronostratigraphic markers for palaeoclimate studies. We present new cryptotephra findings of historical and modern Icelandic eruptions in annually laminated lacustrine sediment records from several sites within a 570 km SW–NE transect across northern Poland. Sediments from the two lakes Wąsoskie and Szurpiły contain glass shards originating from the Plinian Askja ad 1875 eruption and showing bimodal, rhyolitic and dacitic affinities. A further cryptotephra finding in Lake Lubińskie suggests a potential origin from the Hekla ad 1845 eruption. These new findings extend the tephra dispersal map towards the south‐east and provide valuable isochrons for the synchronisation of palaeoclimate proxy data at the termination of the Little Ice Age in central eastern Europe. Very low glass concentrations of modern cryptotephra in Lake Wąsoskie were potentially correlated with the Eyjafjallajökull ad 2010 eruption. Further findings in the uppermost sediments of lakes Szurpiły and Żabińskie in north‐eastern Poland tentatively suggest other sources from either the Hekla and/or Kamchatkan volcanoes.

Lava–water interaction and hydrothermal activity within the 2014–2015 Holuhraun Lava Flow Field, Iceland

Lava that erupted during the 2014–2015 Holuhraun eruption in Iceland flowed into a proglacial river system, resulting in aqueous cooling of the lava and an ephemeral hydrothermal system. We carried out a monitoring study of this system from 2015 to 2018 to document the cooling of the lava over this time, using thermocouple measurements and data-logging sensors. The heat loss rate from advection through this hydrothermal system in August 2015 was ~5.5 × 108 W; since eruption, aqueous cooling likely accounted for ~1% of the total heat loss from the lava. This estimate excludes steam losses from fumaroles as well as any groundwater that was not released to the surface, and thus is a lower bound. Near the terminus of the flow, advection of heat by flowing water may have locally accounted for tens of percent of the total cooling of that part of the flow. Our data quantify the importance of water cooling for this lava flow and can be compared with models to better understand lava–water interactions more generally. We also provide detailed methods for simple, low-cost monitoring of similar instances in the future.

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.

Hekla 1947, 1845, 1510 and 1158 tephra in Finland: challenges of tracing tephra from moderate eruptions

ABSTRACTSeveral cryptotephra layers that originate from Icelandic volcanic eruptions with a volcanic explosivity index (VEI) of ≤ 4 and tephra volumes of < 1 km3 have previously been identified in Northern Europe, albeit within a restricted geographical area. One of these is the Hekla 1947 tephra that formed a visible fall‐out in southern Finland. We searched for the Hekla 1947 tephra from peat archives within the previously inferred fall‐out zone but found no evidence of its presence. Instead, we report the first identification of Hekla 1845 and Hekla 1510 cryptotephra layers outside of Iceland, the Faroe Islands, Ireland and the UK. Additionally, Hekla 1158 tephra was found in Finland for the first time. Our results confirm that Icelandic eruptions of moderate size can form cryptotephra deposits that are extensive enough to be used in inter‐regional correlations of environmental archives and carry a great potential for refining regional tephrochronological frameworks. Our results also reveal that Icelandic tephra has been dispersed into Finnish airspace at least seven times during the past millennium and in addition to a direct eastward route the ash clouds can travel either via a northerly or a southerly transport pathway.

Hazards from lava–river interactions during the 1783–1784 Laki fissure eruption

AbstractInteractions between lava flows and surface water are not always considered in hazard assessments, despite abundant historical and geological evidence that they can create significant secondary hazards (e.g., floods and steam explosions). We combine contemporary accounts of the 1783–1784 Laki fissure eruption in southern Iceland with morphological analysis of the geological deposits to reconstruct the lava–water interactions and assess their impact on residents. We find that lava disrupted the local river systems, impounded water that flooded farms and impeded travel, and drove steam explosions that created at least 2979 rootless cones on the lava flow.Using aerial photographs and satellite-derived digital terrain models, we mapped and measured 12 of the 15 rootless cone groups on the Laki lava field. We have identified one new rootless cone group and provide data that suggest another cone group previously attributed to the 939–940 CE Eldgjá eruption was created by the Laki eruption. We then use contemporary accounts to estimate formation dates and environments for each cone group, which formed in wetland/lake areas, on riverbeds, and near areas of impounded water. Furthermore, comparison with previous field studies shows that assessments using remote sensing can be used to identify and map meter-scale and larger features on a lava flow, although remote mapping lacks the detail of field observations.Our findings highlight the different ways in which lava can interact with surface water, threatening people, property, water supplies, and infrastructure. For these reasons, anticipation of such interactions is important in lava flow hazard assessment in regions with abundant surface water; we further demonstrate that remote sensing can be an effective tool for identifying lava–water interactions in past lava flows.

Volcanoes and climate: the triggering of preboreal Jökulhlaups in Iceland

The Early Holocene (12–8.2 cal ka) deglaciation and pulsed warming was associated in Iceland with two major generations of jokulhlaups around the Vatna ice-cap (Vatnajokull), at ca 11.4–11.2 cal ka and ca 10.4–9.9 cal ka, and major tephra emissions from the Grimsvotn and Barðarbunga subglacial volcanoes. The earliest flood events were recorded inland during the Middle Younger Dryas and their deposits were overlain by the Early Preboreal Vedde Ash (11.8 cal ka). The first Holocene flood events (ca 11.4–11.2 cal ka) are issued from a glacial advance. The second, and major, set of floods was partly driven by the Erdalen cold events and advances (10.1–9.7 10Be ka) initially issued from the Barðarbunga (10.4, 10.1–9.9 ka) and Grimsvotn volcanoes (Saksunarvatn tephra complex, ca. 10.2–9.9 cal ka). These floods were also fed by the residual glacio-isostatic depressions below the Vatnajokull that enabled the storage of meltwaters in large subglacial lakes or aquifers until ca. 9.3 cal ka. This storage was enhanced by ice-damming and permafrost, especially during the twinned Erdalen events. Due to the glacio-isostatic rebound, the general slope was nearly flat, and the valley was partly filled with sediments until ca 10.8 cal ka. Temporary lacustrine deposits in this valley resulted from the very broad splay of waters as for the ca 11.2 cal ka and ca 10.1–9.9 cal ka flood, due to regional permafrost. These floods had a potential duration of several months as they were mostly fed by climate-driven meltwater. The maximal volume evacuated by these events did not greatly exceed 1 × 106 m3 s−1 from the flood-affected transverse profile of the valleys that remain partly filled with sediments.

Complex refractive index of volcanic ash aerosol in the infrared, visible, and ultraviolet.

Very fine silicate-rich volcanic ash, generated by explosive volcanic eruptions, can efficiently be traced downwind with infrared satellite sounders. Their measurements can also be used to derive physical parameters, such as optical depths and effective radii. However, one of the key requirements for accurate retrievals is a good knowledge of the complex refractive index (CRI) of the ash under investigation. In the past, the vast majority of the studies used the CRIs from Pollack et al. [Icarus19, 372 (1973)ICRSA50019-103510.1016/0019-1035(73)90115-2], which are based on measurements of thin slices of volcanic rock, and therefore are not representative for airborne volcanic ash particles. Here, we report measurements of the CRI of volcanic ash in suspension, generated from samples collected from recent high-impact eruptions in Chile (Puyehue-Cordón Caulle, Calbuco, and Chaitén), Iceland (Eyjafjallajökull and Grímsvötn), and Italy (Etna). The samples cover a wide range of ${{\rm SiO}_2}$SiO2 content (46% to 76%) as confirmed by an X-ray fluorescence analysis. In the experimental setup, volcanic ash was suspended in nitrogen through mechanical agitation. Extinction spectra were recorded in the infrared, visible, and ultraviolet spectral regions. The particle size distribution within the airflow was also recorded. An iterative algorithm allowed us to obtain fully consistent CRIs for the six samples, compatible with the observed extinction spectra and the Kramers-Krönig relations. While a good agreement is found with other recently reported CRIs in the UV/Vis, larger differences are found in the longwave infrared spectral region.

Estimating the 3D shape of volcanic ash to better understand sedimentation processes and improve atmospheric dispersion modelling

The sedimentation rate of volcanic ash through the atmosphere influences its travel distance, with important implications for aviation and health. The fall velocity of a particle depends on its size and density, but also shape, and volcanic ash is not spherical. To capture the sedimentation of ash, atmospheric dispersion models use empirical drag equations calibrated using geometric shape descriptors. However, particle shape data are scarce and there is no standard method of shape measurement. In addition, shape measurements are not always available during an eruption, when dispersion models are used operationally to forecast ash hazard. We assess the variability in the shape of volcanic ash from Icelandic eruptions using X-ray computed tomography. To consider how good different drag equations and shape descriptors are at representing the sedimentation of volcanic ash we compare calculated fall velocities to measured fall velocities of volcanic ash in air in a settling column. We then suggest the best drag equations and shape descriptors for use in atmospheric dispersion models. We find that shape-dependent drag equations produce more accurate results than a spherical approximation. However, accurate drag calculations based on the shape descriptor sphericity, which is a function of surface area, require the imaging resolution to be within the range of 102 - 105 voxels per particle (where a voxel is a volumetric pixel) as surface area is sensitive to imaging resolution. We suggest that the large-scale form of the particle impacts sedimentation more than small-scale surface roughness. Shape descriptors based on ratios between principal axis lengths are more practical as they are less variable among particle size classes and much less sensitive to imaging resolution. Finally, we use particle shape data from this study and literature sources to make recommendations on default values for use with atmospheric dispersion models where no shape data are available.

Continuous measurements of riverine chemical constituents reveal the environmental effect of the 2014–2015 Bárðarbunga eruption in Iceland

The 2014–2015 Bárðarbunga eruption caused one of the most intense and widespread volcanic derived air pollution events in centuries. The volcanic plume was tracked all the way to central Europe. Volcanic gas and aerosol dissolved in precipitation and accumulated as aerosol and snow on land in Iceland. Here we report on the continuous monitoring of discharge and dissolved constituents of a direct runoff river located 85 km from the eruption site during the entire snowmelt period in 2015. Osmotic samplers collected continuous water samples so short-lived flood peaks would not be missed. Comparison between results from this 2015 study and data from 1998 to 2013 from the same river showed that average pH was 0.2 units lower in 2015 and the Cl and SO4 average concentration were 36% and 38% higher than prior to the eruption, respectively. Integrated riverine fluxes of H+ and SO4 were two to three times higher during summer 2015 than in the control years, and the Cl flux was 37% higher. The measured excess H+ flux was however only a small fraction of the calculated excess H+ flux stemming from excess SO4 and Cl fluxes in 2015 which can be explained by ion-exchange in the catchment soil, water-rock interaction consuming protons within the catchment, and by elevated sea spray derived Cl and SO4 due to relatively high wind speed during the 2014–2015 winter. In addition, the small H+ increase in the river water can be the cause of the less than expected excess SO4 riverine flux, normalised to the total measured volcanogenic SO2 and HCl emission fluxes (11 Tg/0.1 Tg), which underscores the slow oxidation of SO2 to SO4 in relatively dry weather conditions and reduced sunlight during winter in Iceland. Despite being sensitive to riverine pH and aluminium changes, freshwater ecosystem was not threatened by the eruption, since it did not cause large pH changes and the dissolved aluminium concentration was always low during the study period. This study provided the means to quantify the integrated chemical fluxes and the impact of volcanic emissions on a riverine system in the vicinity of the eruption site and the implication of increased chemical fluxes of solutes of volcanic origin on the system.

Practising an explosive eruption in Iceland: outcomes from a European exercise

A 3 day exercise simulating unrest and a large explosive eruption at Katla volcano, Iceland, was conducted in January 2016. A large volume of simulated data based on a complex, but realistic eruption scenario was compiled in advance and then transmitted to exercise participants in near-real time over the course of the exercise. The scenario was designed to test the expertise and procedures of the local institutions in charge of warning and responding to volcanic hazards, namely the volcano observatory, national civil protection, and the local university-science sector, as well as their interactions with the European science community and the London Volcanic Ash Advisory Centre. This exercise was the first of this magnitude and scope in Iceland and has revealed many successful developments introduced since the 2010 Eyjafjallajökull and 2011 Grímsvötn eruptions. Following the exercise, 90% of participants said that they felt better prepared for a future eruption. As with any exercise, it also identified areas where further development is required and improvements can be made to procedures. Seven key recommendations are made to further develop capability and enhance the collaboration between the volcano observatory, volcano research institutions and civil protection authorities. These recommendations cover topics including notification of responders, authoritative messaging, data sharing and media interaction, and are more broadly applicable to volcanic institutions elsewhere. Lessons and suggestions for how to run a large-scale volcanic exercise are given and could be adopted by those planning to rehearse their own response procedures.

Historical accounts of pre-eruption seismicity of Katla, Hekla, Öræfajökull and other volcanoes in Iceland

Detecting unusual activity leading to the outbreak of a volcanic eruption is of vital importance for the short-term warning to the local population of an impending eruption. The varied volcano types of Iceland and range of ambient conditions at which eruptions occur offer an unusually wide spectrum of volcanic phenomena and volcanic hazards during the initial phase of eruptions. A recent study of eruptions in Iceland during the last four decades of instrumental observations has revealed that all the eruptions had a detectable precursory seismic activity, that under favourable conditions can be used to issue short-term warnings to the surrounding communities. Considerable documentary data also exist for pre-instrumental times extending several centuries back in time, that can be compared to the instrumental experience. This is true in particular for two of the most active volcanoes, Katla and Hekla, that are sufficiently close to the populated areas of the country. All seven confirmed eruptions of Katla since 1625 were preceded by felt earthquakes, beginning one to nine hours before the eruption was detected and two to over twelve hours before a jökulhlaup from this partly sub-glacial volcano reached the inhabited areas. The behaviour of Hekla is quite different. Large eruptions from the main edifice of Hekla since 1510 were generally accompanied by rather weak seismic activity. Earthquakes are usually felt only minutes before the first explosion occurs, in the 1947 case even several minutes after the first explosion of the volcano. Eruptions of the Hekla volcanic system outside the main edifice are, on the other hand, accompanied by considerable seismic activity, and the precursor times may be more than three hours, even much longer. The two historical eruptions of Öræfajökull, in 1362 and 1727, were apparently preceded by felt seismicity, sufficient to alarm the local population.

Operational response and hazards assessment during the 2014–2015 volcanic crisis at Bárðarbunga volcano and associated eruption at Holuhraun, Iceland

On August 16, 2014, an intense seismic swarm started below the eastern part of Bárðarbunga caldera in the north-western part of Vatnajökull ice cap, Iceland, marking the onset of a major rifting event. The intense seismicity, corroborated by a complicated deformation pattern, migrated away from the Bárðarbunga caldera for >45 km, until a small effusive eruption started in Holuhraun, outside of the ice cap, on August 29 which lasted a few hours. On August 31 a second, more intense, eruption started. It lasted 180 days and is the largest effusive eruption in Iceland since the Laki event in 1783–1784. A lava field covered about 84 km2 in the middle of the highlands with a bulk volume of ~1.44 km3. Although the potential danger of ice melting and subsequent flooding coupled with tephra fallout was the main concern at the beginning of the crisis, the main associated hazard turned out to be an abundant and constant release of volcanic gases that polluted the country threatening human health and the environment for several months. Very little (or almost no) ash was produced. The impact of the Holuhraun eruption outside of Iceland was minor if compared with what happened in 2010 when Eyjafjallajökull erupted. However, on three occasions the dense gas cloud released by the fissure eruption reached some European countries where unusually high SO2 concentrations were measured at ground level. Managing and living with such a prolonged effusive event was a major effort for the Icelandic scientific community and civil protection authorities and it significantly affected the local population in the northern and eastern parts of the country.This paper retraces the main events that accompanied the volcanic crisis at Bárðarbunga and focuses on the scientific and operative response provided throughout its duration. Particular attention is given to the direct links between the observed phenomena, monitoring effort, hazard assessment and concrete actions taken by the authorities in charge of risk and mitigation assessment. The different roles of the involved institutions are clarified, and the wide and collaborative response on a national basis is explained.A major finding of this post-event analysis is that a strong internal collaboration between the scientific community and operative institutions is the basic element for proper crisis management. Iceland has established protocols that, while imperfect, ensured a well-coordinated response to the Holuhraun eruption and the preceding unrest, and will continue to provide a prompt and effective response for future events. Important realizations, including the need for a proper ground-based alert level system, have been raised and they will be a matter for further development.

Landscape evolution associated with the 2014–2015 Holuhraun eruption in Iceland

The 2014–2015 Holuhraun eruption in Iceland developed between the outlet glacier Dyngjujökull and the Askja central volcano and extruded a bulk lava volume of over 1 km3 onto the floodplain of the Jökulsá á Fjöllum river, making it the largest effusive eruption in Iceland during the past 230 years. Time-series monitoring using a combination of traditional aerial imaging, unmanned aerial systems, and field-based geodetic surveys, established an unprecedented record of the hydrological response of the river system to this lava flow. We observed: (1) the formation of lava-dammed lakes and channels produced during dam-breaching events; (2) percolation of glacial meltwater into the porous and permeable lava, forming an ephemeral hydrothermal system that included hot pools and hot springs that emerged from the lava flow front; and (3) the formation of new seepage channels caused by upwelling of water around the periphery of the lava flow. The observations show that lava flows, like the one produced by the 2014–2015 Holuhraun eruption, can cause significant hydrological changes that continue for several years after the lava is emplaced. Documenting these processes is therefore crucial for our interpretation of volcanic landscapes and processes of lava–water interaction on both Earth and Mars.

Magma takes the fast lane

Volcanology Knowing the time scale for magma transport is important for developing volcano models and improving eruption forecasts. Mutch et al. used different geochemical tracers to constrain the pressure, temperature, and timing of magma ascent from the bottom of the lower crust for an ancient Icelandic eruption. Surprisingly, the magma took only about 10 days to rocket up from approximately 24 kilometers under the surface and erupt. This rapid connection between the crust and the magma source should focus attention on important pre-eruption events like seismic swarms and large changes in carbon dioxide flux. Nat. Geosci. 12 , 569 (2019).

Estimating the carbon content of the deep mantle with Icelandic melt inclusions

Earth's carbon budget is central to our understanding of the long-term co-evolution of life and the planet. Direct observations of surface reservoirs allow for the detailed quantification of their carbon content. However, the carbon content of Earth's deep interior remains poorly constrained. Here we study olivine-hosted melt inclusions from two Icelandic eruptions, with those from the Miðfell eruption allowing us to investigate the carbon content of the deep mantle. Comparison with the previously studied Borgarhraun eruption highlights the presence of deep, plume-sourced mantle material within the Miðfell source region. Miðfell contains trace element-depleted melt inclusions undersaturated in CO2, which have high CO2/Ba (=396±48) and CO2/Nb (=1832±316), though some inclusions preserve even greater relative carbon enrichment. These observations allow us to reconstruct the CO2 content of the bulk Miðfell source as being >690 ppm. By identifying that Miðfell is a mixture of depleted and deep mantle components, we can estimate a CO2 content for the deep mantle component of 1350±350 ppm; a concentration that is over ten times higher than depleted MORB mantle estimates. Assuming that the deep mantle component identified in Miðfell is representative of a global reservoir, then with our new CO2 estimate and by considering a range of representative mantle fractions for this reservoir, we calculate that it contains up to 14 times more carbon than that of the atmosphere, oceans, and crust combined. Our result of elevated CO2/Ba and CO2/Nb ratios, and carbon enrichment support geochemical bulk Earth carbon models that call for the presence of carbon-rich deep mantle domains to balance Earth's relatively carbon-poor upper mantle and surface environment.