The 1845–46 and 1766–68 eruptions at Hekla volcano:new lava volume estimates, historical accounts and emplacement dynamics
We use new remote sensing data, historical reports, petrology and estimates of viscosity based on geochemical data to illuminate the lava emplacement flow-lines and vent structure changes of the summit ridge of Hekla during the large eruptions of 1845–46 and 1766–68. Based on the planimetric method...
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2020
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Online Access: | https://pure.au.dk/portal/da/publications/the-184546-and-176668-eruptions-at-hekla-volcano(805e6b85-e298-4e3e-8526-aeeb7a672728).html https://doi.org/10.33799/jokull2020.70.035 http://www.scopus.com/inward/record.url?scp=85126714507&partnerID=8YFLogxK |
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ftuniaarhuspubl:oai:pure.atira.dk:publications/805e6b85-e298-4e3e-8526-aeeb7a672728 2023-05-15T16:34:01+02:00 The 1845–46 and 1766–68 eruptions at Hekla volcano:new lava volume estimates, historical accounts and emplacement dynamics Vestergaard, Rikke Pedersen, Gro Birkefeldt Møller Tegner, Christian 2020 https://pure.au.dk/portal/da/publications/the-184546-and-176668-eruptions-at-hekla-volcano(805e6b85-e298-4e3e-8526-aeeb7a672728).html https://doi.org/10.33799/jokull2020.70.035 http://www.scopus.com/inward/record.url?scp=85126714507&partnerID=8YFLogxK eng eng info:eu-repo/semantics/restrictedAccess Vestergaard , R , Pedersen , G B M & Tegner , C 2020 , ' The 1845–46 and 1766–68 eruptions at Hekla volcano : new lava volume estimates, historical accounts and emplacement dynamics ' , Jokull , vol. 2020 , no. 70 , pp. 35-55 . https://doi.org/10.33799/jokull2020.70.035 article 2020 ftuniaarhuspubl https://doi.org/10.33799/jokull2020.70.035 2023-03-01T23:57:07Z We use new remote sensing data, historical reports, petrology and estimates of viscosity based on geochemical data to illuminate the lava emplacement flow-lines and vent structure changes of the summit ridge of Hekla during the large eruptions of 1845–46 and 1766–68. Based on the planimetric method we estimate the bulk volumes of these eruptions close to 0.4 km 3 and 0.7 km 3 , respectively. However, comparison with volume estimates from the well-recorded 1947–48 eruption, indicates that the planimetric method appears to underestimate the lava bulk volumes by 40–60%. Hence, the true bulk volumes are more likely 0.5–0.6 km 3 and 1.0–1.2 km 3 , respectively. Estimated melt viscosity averages for the 1766–68 eruption amount to 2.5 × 10 2 Pa s (pre-eruptive) and 2.5×10 3 Pa s (degassed), and for the 1845–46 eruption 2.2×10 2 Pa s (pre-eruptive) and 1.9×10 3 Pa s (degassed). Pre-eruptive magmas are about one order of magnitude more fluid than degassed magmas. In the 1845–46 and 1947–48 eruptions, SiO 2 decreased from 58–57 to 55–54 wt% agreeing with a conventional model that Hekla erupts from a large, layered magma chamber with the most evolved (silicarich) magmas at the top. In contrast, the lava-flows from 1766–68 reveal a more complicated SiO 2 trend. The lava fields emplaced in 1766 to the south have SiO 2 values 54.9–56.5%, while the Hringlandahraun lava-flow that erupted from younger vents on the NE end of the Hekla ridge in March 1767 has higher SiO 2 of 57.8%. This shows that the layered magma chamber model is not suitable for all lava-flows emplaced during Hekla eruptions. Article in Journal/Newspaper Hekla Aarhus University: Research Hringlandahraun ENVELOPE(-19.639,-19.639,64.034,64.034) Summit Ridge ENVELOPE(-57.038,-57.038,-63.448,-63.448) Jökull 70 1 35 55 |
institution |
Open Polar |
collection |
Aarhus University: Research |
op_collection_id |
ftuniaarhuspubl |
language |
English |
description |
We use new remote sensing data, historical reports, petrology and estimates of viscosity based on geochemical data to illuminate the lava emplacement flow-lines and vent structure changes of the summit ridge of Hekla during the large eruptions of 1845–46 and 1766–68. Based on the planimetric method we estimate the bulk volumes of these eruptions close to 0.4 km 3 and 0.7 km 3 , respectively. However, comparison with volume estimates from the well-recorded 1947–48 eruption, indicates that the planimetric method appears to underestimate the lava bulk volumes by 40–60%. Hence, the true bulk volumes are more likely 0.5–0.6 km 3 and 1.0–1.2 km 3 , respectively. Estimated melt viscosity averages for the 1766–68 eruption amount to 2.5 × 10 2 Pa s (pre-eruptive) and 2.5×10 3 Pa s (degassed), and for the 1845–46 eruption 2.2×10 2 Pa s (pre-eruptive) and 1.9×10 3 Pa s (degassed). Pre-eruptive magmas are about one order of magnitude more fluid than degassed magmas. In the 1845–46 and 1947–48 eruptions, SiO 2 decreased from 58–57 to 55–54 wt% agreeing with a conventional model that Hekla erupts from a large, layered magma chamber with the most evolved (silicarich) magmas at the top. In contrast, the lava-flows from 1766–68 reveal a more complicated SiO 2 trend. The lava fields emplaced in 1766 to the south have SiO 2 values 54.9–56.5%, while the Hringlandahraun lava-flow that erupted from younger vents on the NE end of the Hekla ridge in March 1767 has higher SiO 2 of 57.8%. This shows that the layered magma chamber model is not suitable for all lava-flows emplaced during Hekla eruptions. |
format |
Article in Journal/Newspaper |
author |
Vestergaard, Rikke Pedersen, Gro Birkefeldt Møller Tegner, Christian |
spellingShingle |
Vestergaard, Rikke Pedersen, Gro Birkefeldt Møller Tegner, Christian The 1845–46 and 1766–68 eruptions at Hekla volcano:new lava volume estimates, historical accounts and emplacement dynamics |
author_facet |
Vestergaard, Rikke Pedersen, Gro Birkefeldt Møller Tegner, Christian |
author_sort |
Vestergaard, Rikke |
title |
The 1845–46 and 1766–68 eruptions at Hekla volcano:new lava volume estimates, historical accounts and emplacement dynamics |
title_short |
The 1845–46 and 1766–68 eruptions at Hekla volcano:new lava volume estimates, historical accounts and emplacement dynamics |
title_full |
The 1845–46 and 1766–68 eruptions at Hekla volcano:new lava volume estimates, historical accounts and emplacement dynamics |
title_fullStr |
The 1845–46 and 1766–68 eruptions at Hekla volcano:new lava volume estimates, historical accounts and emplacement dynamics |
title_full_unstemmed |
The 1845–46 and 1766–68 eruptions at Hekla volcano:new lava volume estimates, historical accounts and emplacement dynamics |
title_sort |
1845–46 and 1766–68 eruptions at hekla volcano:new lava volume estimates, historical accounts and emplacement dynamics |
publishDate |
2020 |
url |
https://pure.au.dk/portal/da/publications/the-184546-and-176668-eruptions-at-hekla-volcano(805e6b85-e298-4e3e-8526-aeeb7a672728).html https://doi.org/10.33799/jokull2020.70.035 http://www.scopus.com/inward/record.url?scp=85126714507&partnerID=8YFLogxK |
long_lat |
ENVELOPE(-19.639,-19.639,64.034,64.034) ENVELOPE(-57.038,-57.038,-63.448,-63.448) |
geographic |
Hringlandahraun Summit Ridge |
geographic_facet |
Hringlandahraun Summit Ridge |
genre |
Hekla |
genre_facet |
Hekla |
op_source |
Vestergaard , R , Pedersen , G B M & Tegner , C 2020 , ' The 1845–46 and 1766–68 eruptions at Hekla volcano : new lava volume estimates, historical accounts and emplacement dynamics ' , Jokull , vol. 2020 , no. 70 , pp. 35-55 . https://doi.org/10.33799/jokull2020.70.035 |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.33799/jokull2020.70.035 |
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Jökull |
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70 |
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1 |
container_start_page |
35 |
op_container_end_page |
55 |
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1766023767410081792 |