A multi-scale risk assessment for tephra fallout and airborne concentration from multiple Icelandic volcanoes – Part 2: Vulnerability and impact

This is the final version of the article. Available from EGU via the DOI in this record.We perform a multi-scale impact assessment of tephra fallout and dispersal from explosive volcanic activity in Iceland. A companion paper (Biass et al., 2014; "A multi-scale risk assessment of tephra fallout and airborne concentration from multiple Icelandic volcanoes – Part I: hazard assessment") introduces a multi-scale probabilistic assessment of tephra hazard based on selected eruptive scenarios at four Icelandic volcanoes (Hekla, Askja, Eyjafjallajökull and Katla) and presents probabilistic hazard maps for tephra accumulation in Iceland and tephra dispersal across Europe. Here, we present the associated vulnerability and impact assessment that describes the importance of single features at national and European levels and considers several vulnerability indicators for tephra dispersal and deposition. At the national scale, we focus on physical, systemic and economic vulnerability of Iceland to tephra fallout, whereas at the European scale we focus on the systemic vulnerability of the air traffic system to tephra dispersal. This is the first vulnerability and impact assessment analysis of this type and, although it does not include all the aspects of physical and systemic vulnerability, it allows for identifying areas on which further specific analysis should be performed. Results include vulnerability maps for Iceland and European airspace and allow for the qualitative identification of the impacts at both scales in the case of an eruption occurring. Maps produced at the national scale show that tephra accumulation associated with all eruptive scenarios considered can disrupt the main electricity network, in particular in relation to an eruption of Askja. Results also show that several power plants would be affected if an eruption occurred at Hekla, Askja or Katla, causing a substantial systemic impact due to their importance for the Icelandic economy. Moreover, the Askja and Katla eruptive scenarios considered could have substantial impacts on agricultural activities (crops and pastures). At the European scale, eruptive scenarios at Askja and Katla are likely to affect European airspace, having substantial impacts, in particular, in the Keflavík and London flight information regions (FIRs), but also at FIRs above France, Germany and Scandinavia. Impacts would be particularly intense in the case of long-lasting activity at Katla. The occurrence of eruptive scenarios at Hekla is likely to produce high impacts at Keflavík FIR and London FIRs, and, in the case of higher magnitude, can also impact France's FIRs. Results could support land use and emergency planning at the national level and risk management strategies of the European air traffic system. Although we focus on Iceland, the proposed methodology could be applied to other active volcanic areas, enhancing the long-term tephra risk management. Moreover, the outcomes of this work pose the basis for quantitative analyses of expected impacts and their integration in a multi-risk framework.This work has been funded by the Spanish research project “Atmospheric transport models and massive parallelism: applications to volcanic ash clouds and dispersion of pollutants at an urban micro-scale” (ATMOST, CGL2009-10244) and the Fonds National Suisse project “Volcanic-Ash Dispersal from Selected Icelandic Volcanoes: Risk Assessment for the European Region” (IZK0Z2_142343). S. Biass is supported by SNF (#200021-129997) and ESF/MemoVolc (#5193) subsidies

The onset of an eruption: selective assimilation of hydrothermal minerals during pre-eruptive magma ascent of the 2010 summit eruption of Eyjafjallajokull volcano, Iceland

The complex processes occurring in the initial phases of an eruption are often recorded in the products of its opening stage, which are usually characterized by small volume and limited dispersal, and thus generally poorly studied. The 2010 eruption of Eyjafjallajökull (Iceland) represents a unique opportunity for these investigations thanks to the good preservation of tephra deposits within the ice/snow pack. A detailed geochemical investiga- tion on the glassy groundmass of single ash clasts disclosed a population of fragments with unusual high 87Sr/86Sr (up to 0.70668) for Icelandic magmatism, and anomalous elemental composition with respect to most of the ju- venile material of the eruption. This suggests that during its rise, before intruding into the ice cover, magma at a dyke tip selectively assimilated hydrothermal minerals with seawater-related, high-Sr isotopic ratios (zeolites, silica phases, anhydrite) hosted in altered volcanic/epiclastic rocks. According to the observed precursory seismic- ity, only restricted to few hours before the onset of the eruption, this process could have accompanied subcritical aseismic fracture opening during the days before the eruption, possibly related to stress corrosion-cracking pro- cesses, which enhanced the partial dissolution/melting and subsequent selective assimilation of the host rocks

Satellite detection, long-range transport, and air quality impacts of volcanic sulfur dioxide from the 2014–2015 flood lava eruption at Bárðarbunga (Iceland)

The 2014–2015 Bárðarbunga-Veiðivötn fissure eruption at Holuhraun produced about 1.5 km3 of lava, making it the largest eruption in Iceland in more than 200 years. Over the course of the eruption, daily volcanic sulfur dioxide (SO2) emissions exceeded daily SO2 emissions from all anthropogenic sources in Europe in 2010 by at least a factor of 3. We present surface air quality observations from across Northern Europe together with satellite remote sensing data and model simulations of volcanic SO2 for September 2014. We show that volcanic SO2 was transported in the lowermost troposphere over long distances and detected by air quality monitoring stations up to 2750 km away from the source. Using retrievals from the Ozone Monitoring Instrument (OMI) and the Infrared Atmospheric Sounding Interferometer (IASI), we calculate an average daily SO2 mass burden of 99 ± 49 kilotons (kt) of SO2 from OMI and 61 ± 18 kt of SO2 from IASI for September 2014. This volcanic burden is at least a factor of 2 greater than the average SO2 mass burden between 2007 and 2009 due to anthropogenic emissions from the whole of Europe. Combining the observational data with model simulations using the United Kingdom Met Office's Numerical Atmospheric-dispersion Modelling Environment model, we are able to constrain SO2 emission rates to up to 120 kilotons per day (kt/d) during early September 2014, followed by a decrease to 20–60 kt/d between 6 and 22 September 2014, followed by a renewed increase to 60–120 kt/d until the end of September 2014. Based on these fluxes, we estimate that the eruption emitted a total of 2.0 ± 0.6 Tg of SO2 during September 2014, in good agreement with ground-based remote sensing and petrological estimates. Although satellite-derived and model-simulated vertical column densities of SO2 agree well, the model simulations are biased low by up to a factor of 8 when compared to surface observations of volcanic SO2 on 6–7 September 2014 in Ireland. These biases are mainly due to relatively small horizontal and vertical positional errors in the simulations of the volcanic plume occurring over transport distances of thousands of kilometers. Although the volcanic air pollution episodes were transient and lava-dominated volcanic eruptions are sporadic events, the observations suggest that (i) during an eruption, volcanic SO2 measurements should be assimilated for near real-time air quality forecasting and (ii) existing air quality monitoring networks should be retained or extended to monitor SO2 and other volcanic pollutants