Nordic Volcanological Center, Institute of Earth Sciences, University of Iceland

Mantle volatiles are transported to Earth’s crust and surface by basaltic volcanism. During subaerial eruptions, vast amounts of carbon, sulfur and halogens can be released to the atmosphere during a short time-interval, with impacts ranging in scale from the local environment to the global climate. By contrast, passive volatile release at the surface originating from magmatic intrusions is characterized by much lower flux, yet may outsize eruptive volatile quantities over long timescales. Volcanic hydrothermal systems (VHSs) act as conduits for such volatile release from degassing intrusions and can be used to gauge the contribution of intrusive magmatism to global volatile cycles. Here, we present new compositional and isotopic (δD and δ18O-H2O, 3He/4He, δ13C-CO2, Δ33S- δ34S-H2S and SO4) data for thermal waters and fumarole gases from the Askja and Kverkfj¨oll volcanoes in central Iceland. We use the data together with magma degassing modelling and mass balance calculations to constrain the sources of volatiles in VHSs and to assess the role of intrusive magmatism to the volcanic volatile emission budgets in Iceland. The CO2/ΣS (10􀀀 30), 3He/4He (8.3–10.5 RA; 3He/4He relative to air), δ13C-CO2 (􀀀 4.1 to 􀀀 0.2 ‰) and Δ33S- δ34S-H2S (􀀀 0.031 to 0.003 ‰ and 􀀀 1.5 to +3.6‰) values in high-gas flux fumaroles (CO2 > 10 mmol/mol) are consistent with an intrusive magmatic origin for CO2 and S at Askja and Kverkfj¨oll. We demonstrate that deep (0.5–5 kbar, equivalent to ~2–18 km crustal depth) decompression degassing of basaltic intrusions in Iceland results in CO2 and S fluxes of 330–5060 and 6–210 kt/yr, respectively, which is sufficient to account for the estimated CO2 flux of Icelandic VHSs (3365–6730 kt/yr), but not the VHS S flux (220–440 kt/yr). Secondary, crystallization-driven degassing from maturing intrusions and leaching of crustal rocks are suggested as additional sources of S. Only a minor proportion of the mantle flux of Cl is channeled via VHSs whereas the H2O flux remains poorly constrained, because magmatic signals in Icelandic VHSs are masked by a dominant shallow groundwater component of meteoric water origin. These results suggest that the bulk of the mantle CO2 and S flux to the atmosphere in Iceland is supplied by intrusive, not eruptive magmatism, and is largely vented via hydrothermal fields.

In January 2020, inflation up to 5 cm was detected in the volcanic system of Svartsengi, Reykjanes peninsula (Iceland). The inflation was probably linked to the movement of magma which was estimated to be at a depth of 3-5 km. Shortly after the detection of the inflation, the Scientific Advisory Board responsible for tackling the unrest deemed possible that the unrest could evolve into an effusive eruption. We used both the MrLavaLoba and the DOWNFLOW codes to simulate the area potentially inundated by lava flows in order to assess the hazard posed in case of an effusive eruption. The DOWNFLOW code was used to create a suite of 10,000 simulations which were used to derive maps of the lava flow hazards. These maps can be dynamically updated to account for ongoing modifications suggested by the geophysical signals of the monitoring system. The MrLavaLoba code, in turn, was tuned based on the historical lava flows in the area, so it would be ready to simulate potential lava flow fields if an eruption began. At the time of writing (April 2020), the area appears have experienced two intrusions and is currently in a waning phase. However, the lava flow modeling carried out constitutes an example of rapid response during an ongoing crisis. The post-processing of DOWNFLOW simulations can also allow for preliminary estimations of the time left before lava flow inundates given targets, providing effective support for stakeholders.

The EVER-EST project (European Virtual Environment for Research - Earth Science Themes: a solution) is a H2020 project (2015-2018) aimed at the creation of a Virtual Research Environment (VRE) focused on the requirements of the Earth Science community. The VRE is intended to enhance the ability to collaborate, interoperate and share knowledge and experience between all relevant stakeholders, including researchers, monitoring teams and civil protection agencies. Among the innovations of the project is the exploitation of the “Research Object” concept.