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Eldvörp–Svartsengi

Coordinates: 63°51′50″N 22°26′20″W / 63.86389°N 22.43889°W / 63.86389; -22.43889
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Svartsengi
Svartsengi in August 2004
Highest point
Elevation243 m (797 ft)[1]
Coordinates63°51′50″N 22°26′20″W / 63.86389°N 22.43889°W / 63.86389; -22.43889[1]
Naming
English translationBlack meadow
Language of nameIcelandic
Geography
Geology
Mountain typeVolcanic system
Last eruption2023, ongoing

Svartsengi (Icelandic pronunciation: [ˈsvar̥(t)sˌeiɲcɪ]); "black meadow" in Icelandic) is a volcanic system in the southwest of Iceland on the Southern Peninsula, southeast of Keflavík International Airport and north of the town of Grindavík. Made up of fissures, cones and volcanic craters, it had not been very active for several centuries but it became subject to notable seismic activities in 2020, 2022 and 2023 in connection with the nearby Fagradalsfjall.

Geography

Location

View from the north of Þorbjörn, the crater constituting the highest point of Svartsengi.

Svartsengi is located in the southwest of Iceland, in the west of the Southern Peninsula, which forms the southwest tip of the country.[1]

The Icelandic toponym Svartsengi, literally "black meadow", designates a small valley at the foot of Sýlingarfell1. From here, the Keflavík and its eponymous international airport are 15 km (9.3 mi) to the northwest, the port city of Vogar is 11 km (6.8 mi) to the north, the port city of Grindavík is 4 km (2.5 mi) to the south, and the cape Reykjanes 16 km (9.9 mi) to the southwest. Reykjavik, the national capital, is about 30 km (19 mi) to the northeast.[1] The Svartsengi Power Station and the Blue Lagoon served by routes 43 and 426 are located on the volcanic system due to the local geothermal context1. At the top of Þorbjörn, the highest point of the Svartsengi, there are relay antennas and to the south, on the edge of the volcano, stand the antennas of the Naval Radio Transmitter Facility Grindavik.

The majority of Svartsengi is located in the municipality of Grindavíkurbær with the exception of the northeastern end of the fissures which are found in that of Vogar, both in the region of Suðurnes.[1]

Geology

Lacking a central volcanic cone, the Svartsengi consists of a set of fissures, cones and volcanic craters aligned over 30 km (19 mi) in length and 7 km (4.3 mi) in width, oriented northeast–southwest and surrounded by fields of lava:[2] Þorbjörn (243 m), Sýlingarfell (206 m), Stóra-Skógfell (188 m) and Litla-Skógfell (85 m) in the southwest to the northeast.[1] Two other volcanic systems surround Svartsengi, which is Reykjanes to the west and Fagradalsfjall to the east,[1] both also consisting of a set of fissures, cones and craters oriented in a parallel manner.[2] Thus, although they have similar geological and topographical characteristics with functioning on the same tectonic principle in a rift context, they also possess notable differences in the geochemical composition of their lavas and a certain individuality in their topography and location, which tends volcanologists to consider them more and more as systems distinct from each other.[2] Together with Reykjanes, Fagradalsfjall, Krýsuvík and Brennisteinsfjöll, Svartsengi is part of the Reykjanes volcanic belt.

The lavas emitted by the Svartsengi are exclusively basalts - notably picrite and tholeite - and are in the form of effusive eruptions with a volcanic explosivity index of 1 to 3 and which produce lava flows and projections limited tephras.[2]

History

Aerial view from the west of the Svartsengi: lava fields and fissures extend at the foot of Þorbjörn with at its feet to the left the Blue Lagoon and the Svartsengi Power Station from which plumes of steam rise of water.

During the Holocene, the Svartsengi experienced between twelve and fifteen eruptive periods – a periodicity of approximately 1,000 years – as evidenced by the lava flows associated with it.[2] These recurring activities are represented by a close succession of eruptions over a period of several decades.[2] The last of these eruptions took place in the 13th century with the "Reykjanes fires", a series of effusive eruptions on Svartsengi and Reykjanes which took place between 1210 and 1240 and which produced lava flows with an area of 50 km2 (19 sq mi) for Svartsengi alone.[2]

While the area is usually relatively calm from a geological point of view, intense seismic activity suddenly began on 25 October 2023.[3][4] Several hundred tremors were detected daily with hypocenters between 6 and 1.5 kilometers deep, the vast majority of magnitude less than 3 but a few exceeding this value, up to 4.5 for the most powerful.[3][4] As of 1 November, 10,000 tremors had already been recorded, including 26 exceeding a magnitude of 3.[3] At the same time, the ground rose by more than five centimeters, mainly at around 1.5 kilometers to the southwest of the Blue Lagoon and northwest of Þorbjörn.[3][4] These phenomena were interpreted as the intrusion of magma at a depth of four or five kilometers below the sector most affected by soil uplift.[3][4] Such events hdve already occurred in 2020 and 2022 in the same sector without this leading to an eruption.[4] On 27 October the alert level for aviation was reassessed to yellow.[5][6] On 9 November, seismicity reached levels close to 5 on the Richter scale, which led to the decision to close the Blue Lagoon as a precaution.[7]

2023 earthquakes and eruption

Main article: 2023 Iceland earthquakes
Map of volcanic systems on the Reykjanes Peninsula. The Eldvörp-Svartsengi system is marked here as number 2

In December 2019 volcanic activity began near the hyaloclastite mountain Þorbjörn, which indicated that the Reykjanes Peninsula was beginning a new volcanic cycle after 800 years of inactivity.[8] In the following four years, five magmatic intrusions have formed in the Eldvörp-Svartsengi volcanic system, the first four of which stalled before reaching the surface.[9] During this time volcanic unrest on the peninsula has mostly been associated with the neighboring Fagradalsfjall system, where three out of four confirmed magmatic intrusions have culminated in volcanic eruptions.[10][11][12][13]

On 24 October 2023, a magmatic intrusion underneath the area caused a swarm of intense earthquakes begin.[13] The frequency and intensity of the earthquakes dramatically increased on 10 November, with 20,000 tremors recorded by that time, the largest of which exceeded magnitude 5.3. An evacuation was ordered in the town of Grindavík, which is located near the area of the seismic activity.[13] Large-scale subsidence in and around the town is reported to have caused significant damage.

The earthquakes subsequently decreased in frequency and intensity as the dike intrusion under the town stalled and began to solidify, however concerns remained as if the magma sill southwest of the power plant continued to fill the uplift there would reach the same level as before 10 November by mid-December.

An aerial photo of the 2023 eruption taken by the IMO.

On the evening of 18 December 2023, a volcanic eruption began at near Hagafell about 4km (2.5 miles) north-east of Grindavík[14][15] following a series of small earthquakes at around 21:00 local time.[16] The Icelandic Meteorological Office stated that the eruption stemmed from a fissure with a length of about 3.5 km, with lava flowing at a rate of around 100 to 200 cubic metres per second. An Icelandic Civil Defence official told RUV that the eruption had happened quickly and appeared to be "quite a large event".[17]

Activities

The proximity to the most populated cities in the country including Reykjavik and the significant geothermal potential of the site led to the construction of the Svartsengi Power Station, commissioned in 1977. The water discharged near the power plant and heavily loaded with minerals, most notably in silica, form a body of water in the lava field, leading to the construction of the Blue Lagoon in 1992.[18] During the seismic activity of November 2023, work was begun on measures to protect the plant in case of an eruption. This includes substantial protective walls and a diversionary dike.[19]

See also

References

  1. ^ a b c d e f g "Visualisation". Landmælingar Íslands. 13 November 2023.
  2. ^ a b c d e f g "Reykjanes and Svartsengi volcanic systems". Retrieved 2 November 2023.
  3. ^ a b c d e "Volcanic unrest continues on the Reykjanes Peninsula". Icelandic Meteorological Office. Retrieved 2 November 2023.
  4. ^ a b c d e "25 October-31 October 2023". volcano.si.edu. Retrieved 2 November 2023.
  5. ^ "Importante activité sismique en Islande, potentiel prélude d'une nouvelle éruption volcanique". Le Figaro. 28 October 2023. Retrieved 2 November 2023.
  6. ^ "Swarm of earthquakes in Iceland heralds next volcanic eruption". The Guardian. 27 October 2023. Retrieved 2 November 2023.
  7. ^ Ari Páll Karlsson (9 November 2023). "Bláa lóninu lokað". ruv.is (in Icelandic). Retrieved 9 November 2023.
  8. ^ Sigfússon, Ingólfur Bjarni; Aðalbjörnsson, Tryggvi; Sigurðardóttir, Kristín; Kolbeinsson, Jóhann Bjarni; Guðmundsson, Ingvar Haukur; Þórisson, Arnar (2023-11-21). "Hamfarir í Grindavík gætu boðað nýjan veruleika á Reykjanesskaga". Kveikur (in Icelandic). Retrieved 2023-11-23.
  9. ^ "Litlar hreyfingar mælast innan sigdalsins í og við Grindavík". Veðurstofa Íslands (in Icelandic). Retrieved 2023-11-23.
  10. ^ Óladóttir, Bergrún Arna; Pfeffer, Melissa Anne; Barsotti, Sara; Björnsson, Bogi Brynjar; Titos, Manuel; Gupta, Réne; Stefánsdóttir, Gerður; Tarquini, Simone; Vitturi, Mattia de' Michieli (June 2023). "Langtímahættumat fyrir Reykjanesskaga vestan Kleifarvatns" (PDF). Íslensk eldfjallasjá (in Icelandic). Retrieved 2023-11-24.
  11. ^ "Catalogue of Icelandic Volcanoes - Reykjanes". Icelandic Met Office / University of Iceland / Ríkislögreglustjórinn. Archived from the original on 2 November 2023. Retrieved 2023-11-15.
  12. ^ "Catalogue of Icelandic Volcanoes - Fagradalsfjall". Icelandic Met Office / University of Iceland / Ríkislögreglustjórinn. Archived from the original on 4 July 2023. Retrieved 2023-11-15.
  13. ^ a b c "Magma intrusion possibly extending beneath Grindavík". Icelandic Meteorological office. Archived from the original on 11 November 2023. Retrieved 21 November 2023.
  14. ^ Cite error: The named reference ruverupt was invoked but never defined (see the help page).
  15. ^ "Volcano erupts on Iceland's Reykjanes peninsula". CNN. 2023-12-19. Retrieved 2023-12-19.
  16. ^ "Iceland volcano erupts south of the capital Reykjavik following earthquake swarm". France 24. 2023-12-19. Retrieved 2023-12-19.
  17. ^ "Iceland volcano erupts on Reykjanes peninsula". BBC. 2023-12-19. Retrieved 2023-12-19.
  18. ^ "L'Islande, Texas de la géothermie" [Iceland , the Texas of Geothermal [technology]]. usinenouvelle.com. 21 November 2013. Retrieved 2 November 2023.
  19. ^ Jessica Parker; Nadeem Shad (14 November 2023). "Iceland builds wall to protect power plant from lava". BBC News. Retrieved 14 November 2023.

External links

Wikimedia Commons has media related to Svartsengi.
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