Opin vísindi

The explosive, basaltic Katla eruption in 1918, south Iceland II. Isopach map, ice cap deposition of tephra and layer volume

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dc.contributor Háskóli Íslands
dc.contributor University of Iceland
dc.contributor.author Gudmundsson, Magnus Tumi
dc.contributor.author Janebo, Maria
dc.contributor.author Larsen, Guðrún
dc.contributor.author Högnadóttir, Thórdís
dc.contributor.author Thordarson, Thorvaldur
dc.contributor.author Gudnason, Jonas
dc.contributor.author Jónsdóttir, Tinna
dc.date.accessioned 2022-05-20T12:27:12Z
dc.date.available 2022-05-20T12:27:12Z
dc.date.issued 2021-12-08
dc.identifier.citation Gudmundsson, M.T., Janebo, M.H., Larsen, G., Högnadóttir, Th., Thordarson, Th., Gudnason, J., Jónsdóttir, T. 2021. The explosive basaltic eruption in 1918, south Iceland II: Isopach map, ice cap deposition of tephra and layer volume. Jökull, 71, 21-38.
dc.identifier.issn 0449-0576
dc.identifier.uri https://hdl.handle.net/20.500.11815/3192
dc.description.abstract Due to poor preservation and lack of proximal tephra thickness data, no comprehensive isopach map has existed for the tephra layer from the major eruption of the Katla volcano in 1918. We present such a map obtained by combining existing data on the thickness of the 1918 tephra in soil profiles with newly acquired data from the 590 km2 Mýrdalsjökull ice cap which covers the Katla caldera and its outer slopes. A tephra thickness of 20–30 m on the ice surface proximal to the vents is inferred from photos taken in 1919. The greatest thicknesses presently observed, 30–35 cm, occur where the layer outcrops in the lowermost parts of the ablation areas of the Kötlujökull and Sólheimajökull outlet glaciers. A fallout location within the Katla caldera is inferred for the presently exposed tephra in both outlet glaciers, as estimates of balance velocities imply lateral transport since 1918 of ∼15 km for Kötlujökull, ∼11 km for Sólheimajökull and about 2 km for the broad northern lobe of Sléttjökull. Calculations of thinning of the tephra layer during this lateral transport indicate that the presently exposed tephra layers in Kötlujökull and Sólheimajökull were respectively over 2 m and about 1.2 m thick where they fell while insignificant thinning is inferred for the broad northern lobe of Sléttjökull. The K1918 layer has an estimated volume of 0.95±0.25 km3 (corresponding to 1.15±0.30×1012 kg) whereof about 50% fell on Mýrdalsjökull. About 90% of the tephra fell on land and 10% in the sea to the south and southeast of the volcano. The volume estimate obtained contains only a part of the total volume erupted as it excludes water-transported pyroclasts and any material that may have been left on the glacier bed at the vents. While three main dispersal axes can be defined (N, NE and SE), the distribution map is complex in shape reflecting tephra dispersal over a period of variable wind directions and eruption intensity. In terms of airborne tephra, Katla 1918 is the largest explosive eruption in Iceland since the silicic eruption of Askja in 1875.
dc.description.sponsorship MTG, ÞH: University of Iceland Research Fund, Chief of Police in South Iceland, The Icelandic Road Authority. MHJ: EU Marie Sklodowska-Curie fellowship JG: Landsvirkjun, Fræðslusjóður Suðurlands TJ: GOSVÁ program on volcanic hazard assessment in Iceland
dc.format.extent 21-38
dc.language.iso en
dc.publisher Joklarannsoknafelag Islands
dc.relation.ispartofseries Jökull;71
dc.rights info:eu-repo/semantics/openAccess
dc.subject General Earth and Planetary Sciences
dc.subject Gjóskulög
dc.subject Kötlugos
dc.title The explosive, basaltic Katla eruption in 1918, south Iceland II. Isopach map, ice cap deposition of tephra and layer volume
dc.type info:eu-repo/semantics/article
dc.description.version Peer Reviewed
dc.identifier.journal Jökull
dc.identifier.doi doi:10.33799/jokull2021.71.021
dc.relation.url https://jokull.jorfi.is/wp-content/uploads/2022/02/Gudmundsson_etal_2021_Katla1918_II_Jokull_71.pdf
dc.contributor.department Jarðvísindastofnun (HÍ)
dc.contributor.department Institute of Earth Sciences (UI)
dc.contributor.school Verkfræði- og náttúruvísindasvið (HÍ)
dc.contributor.school School of Engineering and Natural Sciences (UI)

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