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The 2022 Meradalir eruption of the 2021-23 Fagradalsfjall Fires, Reykjanes Peninsula, and associated phenomena

William M. Moreland 1, Thor Thordarson2, Ármann Höskuldsson3, Ingibjörg Jónsdóttir2, Helga Kristín Torfadóttir2, Méline Payet--Clerc2, Iðunn Kara Valdimarsdóttir2, Jacqueline Grech Licari4, Jóna Sigurlína Pálmadóttir2, Diana Brum Da Silveira2, and Lidia Stroganova3

  • Affiliations: 1Icelandic Meteorological Office, Reykjavík, Iceland; 2Faculty of Earth Sciences, University of Iceland, Reykjavík, Iceland; 3Institute of Earth Sciences, University of Iceland, Reykjavík, Iceland; 4School of Geography, Environment and Earth Sciences, Victoria University of Wellington, Wellington, New Zealand 

  • Presentation type: Poster

  • Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 230

  • Programme No: 1.6.9

  • Theme 1 > Session 6

Abstract

The Meradalir eruption began on 3 August 2022 and lasted until 21 August 2022. It was the second of a series of three eruptions to date, bracketed by the 2021 Geldingadalir and 2023 Litli Hrútur eruptions. Together these eruptions make up the Fagradalsfjall Fires -- the opening phase of the current eruptive period on Reykjanes Peninsula, Iceland. The eruption began with >8 vents on a ~250 m-long fissure, later focusing on a single vent that produced 5.7×10⁶ ± 7.6×10⁵ m³ of lava (dense rock equivalent, 30% porosity) over 1 km². Key features included a spatter cone vent, a perched lava pond, and four rubbly pāhoehoe lobes. The vent edifice, primarily dense spatter bombs, reached dimensions of 89×105 m and 18 m high with slopes of 25°--30°. The perched lava pond, formed within hours in a bowl-like depression, reached a maximum height of 35 m by day 9 before draining. The lava field was emplaced over the top of 2021 lava and consisted of four rubbly pāhoehoe lobes each with lengths of approximately 1.4 km. The similarity of these three lengths suggests that 1.4 km was the critical length of lavas emplaced in this scenario. The weight of the 2022 lava compressed the underlying 2021 lava field and forced still-molten 2021 material out through tumuli cracks which flowed along the valley margins as ropey and slabby pāhoehoe. Lidar surveys revealed that the surface of the 2021 lava had bulged by 3 m in the south and 3.6 m in the north.