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. Pedersen, Melissa A. Pfeffer, Sara Barsotti, Simone Tarquini, Mattia de' Michieli Vitturi, Bergrún Óladóttir, and Ragnar Heiðar Þrasstarson

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: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on nhess-2022-166', Anonymous Referee #1, 07 Dec 2022
    • AC1: 'Reply on RC1', Gro Pedersen, 14 Mar 2023
  • RC2: 'Comment on nhess-2022-166', Anonymous Referee #2, 12 Jan 2023
    • AC2: 'Reply on RC2', Gro Pedersen, 14 Mar 2023

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.