User:Prioryman/Reykjanes Fires
The Reykjanes Fires (Icelandic: Reykjaneseldar) were a series of volcanic eruptions that took place on the Reykjanes Peninsula in south-west Iceland between approximately 1210 and 1240. The peninsula was subsequently quiescent for 800 years until a fresh series of eruptions began in 2021, which have been called the New Reykjanes Fires.
Geology
The Reykjanes Peninsula is a continuation of the mostly submarine Reykjanes Ridge, a part of the Mid-Atlantic Ridge Its topography was formed by glaciers and volcanism, with basaltic lava fields covering a good part of the peninsula, in between volcanoes of subglacial as well as subaerial origin, namely tuyas, hyaloclastic ridges (tindars), shield volcanoes and crater rows.[1]
The Reykjanes volcanic belt, one of the present day volcanic zones of Iceland, consists (depending on author) of 3 to 6 or even 7 volcanic systems, arranged en echelon, i.e. more or less side by side, and in an average 40° angle to the spreading direction NE–SW over the peninsula.[2] [3] Most of the volcanic systems, because they are on top of a rift segment, show a tendency for basaltic fissure eruptions.[2] There are tephra deposits from both offshore explosive Holocene eruptions, some of whom were from volcanoes of the Reykjanes volcanic system,[4] and the most recent Hengill eruption.[5] Only the Hengill volcanic system, the most eastern system, has an additional complex central volcano at the intersection with the West volcanic zone of Iceland and South Iceland seismic zone.[6][5]
Eruptions of 1210–1240
A number of off- and onshore eruptions at Reykjanes are recorded by medieval Icelandic annals and sagas as having taken place between 1210 and 1240.[7] As well as depositing tephra across the peninsula, they produced dozens of square kilometres of lava flows, now known as the Yngra Stampahraun, Eldborgarraun yngra, Illahraun and Arnasetursraun. The eruptions are known as "fires" for being a series of eruptions over a specific period in the same area.[8] The specific events recorded were:
- 1210
- 1211, possibly a continuation of the 1210 event and probably an offshore Surtseyan eruption that is known to have produced large quantities of pumice.[7] According to the Konungsannáll, this was accompanied by an earthquake in which fourteen men perished and "fire came up from the sea", likely in August or September 1211.[9] The Vatnsfell tuff cones northwest of Valahnúkamöl were likely created in this eruption, which would have taken place explosively underwater.[10] The eruptions created new land, leaving the craters a short distance inland.
- 1223, possibly associated with the Yngri-Stampar crater row and adjacent lavas north of where the Reykjanes Power Station now stands. (The craters may alternatively have formed in 1211.)[10]
- 1226, a lengthy eruption or series of eruptions which the Íslendinga saga records as "the Sand-Summer, because fire erupted in the sea off Reykjanes and there was a great fall of ash". It caused "much grasslessness" across the peninsula which resulted in a "sand-winter [which] was a very hard winter for the livestock";[11] this appears to record a an explosive eruption which probably took place several kilometres offshore.[7] Tephra fell over a wide area of the peninsula, as far away as Reykjavik, and is known as the Miðaldarlagið or Middle Ages Tephra. It is now an important dating marker for eruptions on the peninsula. Its source is unknown but may have been the volcanic islet of Eldey, which is believed to have erupted during the Reykjanes Fires.[10]
- 1227, probably the same event as 1226, overlapping the years; also produced a large amount of pumice.[7]
- 1231, another "sand-winter"; tephra has been attributed to this event.[7]
- 1238
- 1240, an event recorded as having made the skies "red as blood". This implies a sulphur-rich volcanic plume which caused regional atmospheric perturbations, likely resulting from a large effusive basaltic eruption. The most likely candidates for this event is an area north of Svartsengi where the Arnasetur and Illarhaun lava fields are situated, covering an area of as much as 50 km2 (19 sq mi). They have been dated to a few years after the Miðaldarlagið fell, and may represent the final event in the Reykjanes Fires.[12][10]
New Reykjanes Fires
References
- ^ G.B.M. Pedersen, P. Grosse: Morphometry of subaerial shield volcanoes and glaciovolcanoes from Reykjanes Peninsula, Iceland: Effects of eruption environment. Journal of Volcanology and Geothermal Research 282, (2014), 115-133. Accessed 21 August 2020.
- ^ a b Sæmundsson, K.; Sigurgeirsson, M.Á.; Friðleifsson, G.Ó. (2020). "Geology and structure of the Reykjanes volcanic system, Iceland". Journal of Volcanology and Geothermal Research. 391 (106501). doi:10.1016/j.jvolgeores.2018.11.022.
- ^ Andrésdóttir, Þóra Björg (2018). Volcanic hazard and risk assessment at Reykjanes, vulnerability of infrastructure. Masters thesis (PDF) (Thesis). University of Iceland. pp. 1–89. Retrieved 28 December 2023.
- ^ Sigurgeirsson, Magnús Á.; Einarsson, Sigmundur (2019). "Catalogue of Icelandic Volcanoes - Reykjanes and Svartsengi volcanic systems". Icelandic Meteorological Office, Institute of Earth Sciences at the University of Iceland, Civil Protection Department of the National Commissioner of the Iceland Police. Retrieved 30 December 2023.
- ^ a b Sæmundsson, Kristján (2019). "Catalogue of Icelandic Volcanoes - Hengill". Icelandic Meteorological Office, Institute of Earth Sciences at the University of Iceland, Civil Protection Department of the National Commissioner of the Iceland Police. Retrieved 30 December 2023.
- ^ Thor Thordarson, Armann Hoskuldsson: Iceland. Classic geology of Europe 3. Harpenden 2002, p.14 and 63.
- ^ a b c d e Austin, W.E.N.; Abbott, P.M.; Davies, S.M.; Pearce, N.J.G.; Wastegård, S. (2014). Marine Tephrochronology. Geological Society Special Publications. Geological Society. ISBN 978-1-86239-641-8. Retrieved 2024-02-08.
- ^ "Reykjaneseldar". Náttúruminjasafn Íslands. 2021-05-04. Retrieved 2024-02-09.
- ^ McCreesh, B. (2019). The Weather in the Icelandic Sagas: The Enemy Without. Cambridge Scholars Publishing. p. 35. ISBN 978-1-5275-2559-7. Retrieved 2024-02-08.
- ^ a b c d Thordarson, T.; Höskuldsson, Á. (2014). Iceland. Classic Geology in Europe. Dunedin Academic Press. ISBN 978-1-78046-511-1. Retrieved 2024-02-09.
- ^ McCreesh, p. 15
- ^ Sigurgeirsson, Magnús Á.; Sigmundur, Einarsson (2019). "Reykjanes and Svartsengi volcanic systems". Icelandic Meteorological Office, Institute of Earth Sciences at the University of Iceland, Civil Protection Department of the National Commissioner of the Iceland Police. Retrieved 2 November 2023.