23 Jun 2022
23 Jun 2022
Status: this preprint is currently under review for the journal NHESS.

Lava flow hazard modelling during the 2021 Fagradalsfjall eruption, Iceland: Applications of MrLavaLoba

Gro B. M. Pedersen1, Melissa A. Pfeffer2, Sara Barsotti2, Simone Tarquini3, Mattia de' Michieli Vitturi3,4, Bergrún Óladóttir2, and Ragnar Heiðar Þrasstarson2 Gro B. M. Pedersen et al.
  • 1Nordic Volcanological Center, Institute of Earth Sciences, University of Iceland, Reykjavík, 102, Iceland
  • 2Icelandic Meteorological Office, Reykjavík, 105, Iceland
  • 3Istituto Nazionale di Geofisica e Vulcanologia, Pisa, 56127, Italy
  • 4Department of Geology, University at Buffalo, Buffalo, New York 14260, USA

Abstract. On March 19, 2021, the first eruption in ca. 800 years took place in Fagradalsfjall on the Reykjanes Peninsula, in the backyard of the capital Reykjavík. This effusive eruption was the most visited eruption in Iceland to date and needed intense lava flow hazard assessment and became a test case for hazard assessment for future eruptions on the Peninsula, which can issue lava into inhabited areas or inundate essential infrastructure. 

In this study we documented how lava flow modelling strategies were implemented using the stochastic code MrLavaLoba, evaluating hazards during the 6-month long effusive event. Overall, the purposes were three-fold; (a) Pre-eruption simulation to investigate potential infrastructure at danger for lava flow inundation (b) Syn-eruptive simulations for short-term (two weeks’ time frame) lava flow hazard assessment and (c) Syn-eruptive simulations for long-term hazard assessments (months to years). Furthermore, strategies for lava barrier testing were developed and incorporation of near-real time syn-eruptive topographic models were implemented.

During the crisis the code was updated to increase functionalites such as considering multiple active vents as well as code optimization that led to a substantial decrease in the computational time required for the simulations, speeding up the delivery of final products.

Gro B. M. Pedersen et al.

Status: open (until 04 Aug 2022)

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Gro B. M. Pedersen et al.

Gro B. M. Pedersen et al.


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Short summary
The lava eruption at Fagradalsfjall 2021 was the most visited eruption in Iceland with thousands of visitors per day for 6 months. To address the short-and long-term danger of lava inundating infrastructure and hiking paths we used the lava flow model MrlavaLoba before and during the eruption. These simulations helped communicate lava hazards to stakeholders and can be used as test case for lava hazard assessment for future eruptions in the area, which is likely to be more destructive.