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Earth of fire

Actualité volcanique, Article de fond sur étude de volcan, tectonique, récits et photos de voyage

Publié par Bernard Duyck
Publié dans : #Excursions et voyages

The Icelandic weekend to see the eclipse was also an opportunity to glimpse the volcanism of the south coast of the island.

Emerging from Keflavik airport, the Reykjanes peninsula offers a first contact. The volcanic system Reykjanes, southwest of the peninsula of the same name, is an extension in surface of the Mid-Atlantic Ridge, includes a wide range of eruptive fissures system, craters and postglacial small basaltic shields.


 

Lavas in the Reykjanes peninsula / Grindavik - photo © 2015 Bernard Duyck

Lavas in the Reykjanes peninsula / Grindavik - photo © 2015 Bernard Duyck

Lavas in the Reykjanes peninsula / Grindavik - photo © 2015 Bernard Duyck

Lavas in the Reykjanes peninsula / Grindavik - photo © 2015 Bernard Duyck

The greater part of the Reykjanes volcanic system is covered with lava emitted during the Holocene. Subaerial eruptions are indicated in the course of the 13th century on a group of cracks aligned NE-SW, as many underwater eruptions in the 12th century, some of which have formed ephemeral islands.

 

Volcanic centers and high temperature geothermal areas - Doc. Icelandic geosurvey

Volcanic centers and high temperature geothermal areas - Doc. Icelandic geosurvey

Volcanic and geothermal areas on parallel cracks in the Reykjanes peninsula - Local indicative sign - photo © 2015 Bernard Duyck

Volcanic and geothermal areas on parallel cracks in the Reykjanes peninsula - Local indicative sign - photo © 2015 Bernard Duyck

Gunnuhver / Grindavik is the geothermal area further west, as close as the boundary between the North American and Eurasian tectonic plates. Infiltration waters probably mixed with sea water are heated by magma, and the steam that emanates reached more than 300 ° C, making it one of the geothermal areas among the warmest on Reykjanes.

Reykjanes is subject to significant seismic activity, characterized by low magnitude swarms. Some of them have caused a slip at a crack through Gunnuhver; these ground motions have revitalized the intermittent steam field and allowed an outlet to the deep water reservoir in the form of geysers. The 1918 earthquake had formed a powerful geyser with a bubble of 5 meters, named "Hverinn 1918". Reactivated in September 1967 by an earthquake, he erupting with a throw over 12 meters high. A geothermal rilling ended its existence in 1983.

The waters acidified by gases, primarily carbon dioxide and hydrogen sulfide, altered volcanic rocks to turn today into mud pots.

The vapors from the soil have given their importance increased after the start of the industrial exploitation in 2006. From 2008 to 2010, the area was partially closed by the Civil Defense because of the danger of eruption, and destruction of the boardwalks.

 

Gunnhuver / Grindavik : hot springs and fumaroles - photo © 2015 Bernard Duyck

Gunnhuver / Grindavik : hot springs and fumaroles - photo © 2015 Bernard Duyck

Grindavik - geothermal installations - photo © 2015 Bernard Duyck
Grindavik - geothermal installations - photo © 2015 Bernard Duyck

Grindavik - geothermal installations - photo © 2015 Bernard Duyck

Gunnhuver - bridge destroyed by the activity at the beginning of the decade - photo Iceland islandsmyndir.is / Rafn Sigurbjörnsson

Gunnhuver - bridge destroyed by the activity at the beginning of the decade - photo Iceland islandsmyndir.is / Rafn Sigurbjörnsson

The name Gunnhuver derives from that of a ghost, Guðrún Önundardóttir, nicknamed "Gunna". According to a common legends about this, she was a farmer near Kirjubol, a property owned by a lawyer, Vilhjalmur Jonsson. When Gunna did not honor the payment of the rent, Vilhjalmur took away his only possession, a cooking pot. Gunna became furious and refused to drink holy water and fell dead. On the way to the cemetery, holders of the coffin noted that it was becoming strangely lighter. And when the grave was dug, people heard; "No need to dig deep, no plans long  to lie"  ... it was obviously Gunna speaking, now a hate spectrum ! The next night, the body of Vilhjalmur was found on the moor, blue and with broken bones ... the revenge of Gunna.

Another story tells that a priest named Eirikr felt capable of exorcism, and finally threw Gunna a geyser, which took his name. According to the tales of the time, you should be able to see her refusing to let it grow.

Reykjanesvitti - photo © 2015 Bernard Duyck

Reykjanesvitti - photo © 2015 Bernard Duyck

The geothermal area is close to the Reykjanes lighthouse, in Icelandic Reykjanesvitti, the oldest lighthouse in Iceland.

The octagonal original structure dates from 1878; the lighthouse was destroyed eight years after its construction by an earthquake. In 1929, the new lighthouse, in the traditional look but in concrete this time, was equipped with modern lighting, emitting a flash every 30 seconds. The focal plane is 73 meters above the level of the sea.

To follow, the volcanic system Krísuvík

 

Sources:

- Global Volcanism Program - Reykjanes

- Icelandic geosurvey - link

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