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[EN VIDÉO] How does magma form before a volcanic eruption? Magma is the origin of the formation of volcanoes. This molten rock, which bubbles up in the crater, comes from a partial melting of the Earth’s mantle. Futura met Jacques-Marie Bardintzeff, doctor in volcanology, who tells the origin of magma.
We take the same and start again ? Last year, among the sites on Youtube and on Facebook which were particularly interesting to consult to follow the news of the spectacular eruption which had started on March 19, 2021 in Iceland, there were those of Volcano Chaser and of The Reykjavik Grapevine, an Icelandic magazine written in English. Its editor, Valur Grettisson, regularly visited the site of the eruption, providing advice for those undertaking a pilgrimage to the active volcano and interviewing volcanologists studying phenomena eruptive like in the video below.
This is the great return of Valur Grettisson in this video on the new Icelandic eruption in 2022. To obtain a fairly faithful French translation, click on the white rectangle at the bottom right. The English subtitles should then appear. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Translate automatically”. Choose “French”. © The Reykjavik Grapevine
Remember that, in 2021, it all started with a fissure eruption about 200 meters long in the Geldingadalir, literally in French “the valley of the geldings” a valley on the eastern flank of the Fagradalsfjall, an Icelandic toponym meaning “the mountain of the beautiful valley” and designating a volcanic system where no eruption had occurred for about 800 years.
An eruption of unknown duration
Lava basalt very fluid which escaped from the crack had then built in a few hours two small cones of slag. The new eruption which began on August 3, 2022 is again occurring in the form of a fissure eruption but 300 m long this time and according to the first aerial measurements, the debit Average lava flow in the first hours of the eruption was 32 cubic meters per second, four to five times more than at the start of the eruption last year!
As of August 5, 2020, activity appears to be reducing as the lava flow had dropped to 18 cubic meters per second the previous day, as well as seismic activity which had also suggested as in 2021 that magma fracturing the rock by pressure hydraulics rising to the surface could lead to a new eruption.
Other images where we can also see Valur Grettisson and, again, the volcanologists he interviewed in the previous video although this video is not members of the Reykjavik Grapevine. To obtain a fairly accurate French translation, click on the white rectangle at the bottom right. The English subtitles should then appear. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Translate automatically”. Choose “French”. © Volcano Chaser
There are no ash clouds, but there are always emissions of gas, carbon dioxide, Hydrogen sulfide and halides, which can be harmful near the site of the eruption, site which is very close to that of the eruption of 2021 with flows which are superimposed on the previous ones. The dioxide of sulfur is particularly to be taken into account and it comes in the form of a blue mist.
The lava flow which moves away from the crack is trapped by the relief of the Meradalir valley, it is therefore not very extensive but it tends to thicken giving a fabulous spectacle but of which we do not yet know very well , just like in 2021, how long will it last…
Warning signs of an impending volcanic eruption in Iceland?
Article of Ludovic Leduc Published on 02/08/2022
A seismic swarm began on Saturday July 30 at the level of the peninsula of Reykjanes, in the southwest of Iceland. Even if the inhabitants of this sector no longer count the tremors that have been occurring there for 2 and a half years, this recent activity is particularly intense. Does this announce a volcanic eruption ?
Since noon, July 30, more than 5,500 earthquakes occurred on the Reykjanes peninsula, an average of two per minute! Yes, Iceland is an island geologically active, but for comparison, “only” 800 earthquakes were recorded on the island during the week between July 18 and 24, for example. These are mainly events of low magnitudes, but the swarm also has 94 earthquakes of magnitude greater than 3 at this time. Moreover, since midnight this 1er August, six events of magnitude greater than 4 have occurred, suggesting that this crisis is intensifying…
A few of these earthquakes have been felt, including the one yesterday at 5:47 p.m., of magnitude 5.4, which was perceived up to more than 130 km from theepicenter ! This earthquake caused some damage, in the village of Grindavik in particular.
The 5.4 magnitude earthquake felt by one of the webcams which points to the eruptive cone formed during last year’s eruption. Notice how this one reacts!
Damage following the 5:47 p.m. earthquake.
A seismic swarm probably of magmatic origin
This seismic swarm is part of a seismo-volcanic crisis which began at the beginning of the year 2020 on this Reykjanes peninsula and which saw several seismic swarms occur, as well asa six-month eruption last year. It is likely that this swarm is due to movements magma at depth, but in many cases it does not have enough strength to reach the surface. As a result, while an eruption in Iceland soon is not certain, it is now more likely. This is why the Icelandic authorities have placed the sector on yellow alert for aviation…
Journey to the Center of the Earth: the entrance! Nope ! this image does not show you the entrance to the Snæfellsjökull volcano, the stratovolcano surmounted by an ice cap which culminates at 1,446 meters in altitude and which, in the famous novel Jules Vernes, had allowed Arne Saknussemm to begin his “Journey to the center of the earth”. But we fly over one of the Thrihnukagigur craters which allows us to enter a magma chamber, a unique possibility in the world. © Florian Ledoux, all rights reserved.
Journey to the center of the Earth: the descent by elevator Visitors can take a kind of elevator to go down in about 6 minutes within the magma chamber of Thrihnukagigur between the months of May and October.© Florian Ledoux, all rights reserved.
Journey to the center of the Earth: a magma chamber At a depth of more than 200 meters, you then come to the floor of a cavity, over an area of 3,270 m². It is a kind of magma chamber in which, unlike many other volcanoes, the lava did not freeze at the end of the eruption. The cavity left has not collapsed either.© Florian Ledoux, all rights reserved.
The Thrihnukagigur magma chamber: I At the bottom of the volcanic conduit which allowed the descent, and which we see on several of the photos of the slide show, we can explore the cavity left in the magma chamber. © Florian Ledoux, all rights reserved.
The Thrihnukagigur Magma Chamber: II We see on this photo two dark vertical dykes, that is to say injections of lava forming a kind of tubes in the already solidified surrounding rock of the volcanic chamber. The temperature of the lava in the dykes caused the color changes which locally colored the rocks red.© Florian Ledoux, all rights reserved.
The Thrihnukagigur Magma Chamber: III In 4,000 years, the water has left several deposits of mineral matter that richly color in red, yellow, green, blue and black the walls of the conduit of the only volcano in the world in which visitors can explore on an area of 3,270 m², this what the magmatic chambers, usually much deeper, must look like under volcanoes. © Florian Ledoux, all rights reserved.
The Thrihnukagigur Magma Chamber: IV The temperature at the bottom of the basalt chamber is always around 5-6°C. © Florian Ledoux, all rights reserved.
The Thrihnukagigur Magma Chamber: V The colors due to the infiltrations on the basalt walls can be interpreted in the following way: the reds for the oxidized iron, the yellows for the sulfur and the greens for the components with copper. © Florian Ledoux, all rights reserved.
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