Insights into volcanic hazards and plume chemistry from multi-parameter observations: the eruptions of Fimmvörðuháls and Eyjafjallajökull (2010) and Holuhraun (2014–2015)

Abstract

The eruptions of Eyjafjallajökull volcano in 2010 (including its initial effusive phase at Fimmvörðuháls and its later explosive phase from the central volcano) and Bárðarbunga volcano in 2014–2015 (at Holuhraun) were widely reported. Here, we report on complementary, interdisciplinary observations made of the eruptive gases and lavas that shed light on the processes and atmospheric impacts of the eruptions, and afford an intercomparison of contrasting eruptive styles and hazards. We find that (i) consistent with other authors, there are substantial differences in the gas composition between the eruptions; namely that the deeper stored Eyjafjallajökull magmas led to greater enrichment in Cl relative to S; (ii) lava field SO2 degassing was measured to be 5–20% of the total emissions during Holuhraun, and the lava emissions were enriched in Cl at both fissure eruptions—particularly Fimmvörðuháls; and (iii) BrO is produced in Icelandic plumes in spite of the low UV levels.

Magmatic Controls on Volcanic Sulfur Emissions at the Iceland Hotspot

“…This is a non-peer reviewed manuscript that has been submitted to Geochemistry, Geophysics, Geosystems 8. The petrological method also neglects post-eruptive outgassing from cooling lava, which is an additional source of volcanic pollution (Óskarsson et al, 1984;Thordarson et al, 1996;Simmons et al, 2017;Pfeffer et al, 2018;Sigmarsson et al, 2020;Donovan et al, 2023). This process disproportionately affects F and Cl, which only reach melt saturation as their concentrations in residual melts are driven up by microlite crystallization in cooling lava fields.…”

“…Slow diffusivity of S in silicate melts may cause disequilibrium degassing (Lerner et al, 2021), which may explain commonly observed matrix glass S contents above the solubility limit of melts at surface pressures. The residual sulfur is progressively degassed from a cooling lava field, as seen in progressively waning S concentrations in matrix glasses with increasing distance to the vent and measurable SO2 degassing of lava fields observed by field measurements ( (Lerner et al, 2021, Donovan et al, 2023. For this reason, we consider ΔSmax to be a more reliable indicator of total SO2 release.…”

Magmatic Controls on Volcanic Sulfur Emissions at the Iceland Hotspot

“…Slow diffusivity of S in silicate melts may cause disequilibrium degassing (Lerner et al, 2021), which may explain commonly observed MG S contents above the vapor solubility limit of melts at surface pressures. The residual sulfur is progressively degassed from a cooling lava field, as seen in progressively waning S concentrations in matrix glasses with increasing distance to the vent and measurable SO 2 degassing of lava fields observed by field measurements (Donovan et al, 2023;Lerner et al, 2021). For this reason, we consider ΔS max to be a more reliable indicator of total SO 2 release.…”

“…Actual volcanic volatile emissions may additionally involve input from magmatic S‐bearing volatile phases or external sources of volatiles (see Section 5.2). The petrological method also neglects post‐eruptive outgassing from cooling lava, which is an additional source of volcanic pollution (Donovan et al., 2023; Óskarsson et al., 1984; Pfeffer et al., 2018; Sigmarsson et al., 2020; Simmons et al., 2017; Thordarson et al., 1996). This process disproportionately affects F and Cl, which have initial concentrations far below their melt saturation values.…”

“…Volatiles in volcanic gas plumes can be measured by satellite instruments (e.g., Carboni et al, 2019;Carn et al, 2017;Esse et al, 2023;Schmidt et al, 2015) or by ground-based measurements (e.g., Donovan et al, 2023;Ilyinskaya et al, 2017;Kern et al, 2020;Pfeffer et al, 2018Pfeffer et al, , 2024Scott et al, 2023;Vignelles et al, 2016). However, direct measurements are only available for a relatively small selection of post-1970s eruptions globally and in Iceland (Oppenheimer et al, 2011).…”