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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 : #Actualités volcaniques

The 100 days of the Icelandic eruption at Holuhraun just been celebrated by the Icelandic Met Office staff.

100 days Holuhraun festivals in IMO - cakes are successful and smiles are at the measure of harvested scientific results - photo IES / Twitter

100 days Holuhraun festivals in IMO - cakes are successful and smiles are at the measure of harvested scientific results - photo IES / Twitter

Eruption of Holuhraun - photo lukas-gawenda.de / pic.twitter.com-WairVbpIki / 12.09.2014

Eruption of Holuhraun - photo lukas-gawenda.de / pic.twitter.com-WairVbpIki / 12.09.2014

The fissure eruption began on August 31, 2014; it is characterized by an importantcontinuous and stable emission of lava. The petrological analysis of the magma shows a primitive basalt, of  chemical composition typic of the Bárðarbunga's volcanic system. It also suggests that this type of magma has stabilized between 9 and 20 km deep, which means he has not resided in the shallow crust.

From an initial crack of 1500 meters, the lava has spread to form a vast lava field that reaches on 5 December a surface of 76.2 km² ... and the eruption can still continue for months.

 

The lava field of the Holouhraun 12/08/2014 - photo Air Iceland

The lava field of the Holouhraun 12/08/2014 - photo Air Iceland

To the left, extent of the lava field, 05/12/2014 - Doc. IES - to the right, changing of the lava field during the 100 days (29.08 - 14.11) - Doc. based on SLAR imagery from the Icelandic Coast Guard. Coordinates and outlines: Icelandic Meteorological Office - click to enlarge ..To the left, extent of the lava field, 05/12/2014 - Doc. IES - to the right, changing of the lava field during the 100 days (29.08 - 14.11) - Doc. based on SLAR imagery from the Icelandic Coast Guard. Coordinates and outlines: Icelandic Meteorological Office - click to enlarge ..

To the left, extent of the lava field, 05/12/2014 - Doc. IES - to the right, changing of the lava field during the 100 days (29.08 - 14.11) - Doc. based on SLAR imagery from the Icelandic Coast Guard. Coordinates and outlines: Icelandic Meteorological Office - click to enlarge ..

The new lava field is the most extensive ever seen in Iceland since the eruption of Laki in 1783-1784, and probably the third largest on Earth since this date.

But everything is relative ... with some supporting figures.
- Eruption 2014 Holuhraun: duration over 100 days, still ongoing -  emitted volume of lava : < 2 km³ - extension to 12/05/2014: 76.2 km²
- Laki eruption in 1783-1784: Duration: 8 months - lava emitted volume: 14.7 cubic kilometers - lava field 565 km²
- Eruption of Eldgjá in 934: Duration: about six years - issued volume of lava: 18.3 km³.- lava field: 781 km².

Either at a constant rate, a ratio of 1.83 km³ / month for Laki, 0.66 km³ / month for Holuhraun, and 0.25 km³ / month for Eldgjá.

Comparison of surfaces covered by lava eruptions of Holuhraun, Laki and Eldgjá - doc IMO / IES / Natural Hzards group - References: Eldgjá and outlines Laki and Eldgjá volume from Thordarson et al. 2001. Volume of Laki from Thordarson et al. 1993. Nornahraun data from the University of Iceland, Institute of Earth Sciences' Volcanology and Natural Hazards Group. Specialist William Moreland.

Comparison of surfaces covered by lava eruptions of Holuhraun, Laki and Eldgjá - doc IMO / IES / Natural Hzards group - References: Eldgjá and outlines Laki and Eldgjá volume from Thordarson et al. 2001. Volume of Laki from Thordarson et al. 1993. Nornahraun data from the University of Iceland, Institute of Earth Sciences' Volcanology and Natural Hazards Group. Specialist William Moreland.

The amount of gas emitted by the eruption of Holuhraun is important, and we must go back 150 years back to find an event with a comparable impact on health and environment : Trölladyngja.

Since that time, the gas monotoring has improved. The IMO has used the FTIR and DOAS instruments to estimate the flux of SO2, and other components of the volcanic cloud, in which the present gases are mainly SO2, CO2, hydrochloric and hydrofluoric acid, and vapor water.

A wide range is coming out this mesurements, with respect to a constant emission of gas to date, between 3.5 Mt and 11.2 Mt, respectively considering the average flow and the emission peak.

Compared with the eruption of Laki, the latter issued between 5 to 15 times more gas than the eruption of Holuhraun (122 Mt of SO2 in 8 months, or about 51 Mt in 100 days, at constant flow)
 

Gases emitted by the eruption of Holuhraun - Ragnar Axelsson Photo (RAX) 09/12/2014 - Iceland Review.

Gases emitted by the eruption of Holuhraun - Ragnar Axelsson Photo (RAX) 09/12/2014 - Iceland Review.

It is also the first time that we can see the long term effects on human and animal health of that air pollution by volcanic gas emissions.

Another problem is emerging : the pollution generated by the eruption causes acid rain, and in the Icelandic winter, acid snow which accumulate
in the highlands. Scientists fear that the acidity levels of lakes and rivers will greatly increase with the melting of the snow in the spring, and do alter the vegetation and the ecology of drained areas ... measures should be taken as soon as the snow begins to melt in 2015.

The beauty of the phenomenon should not obscure the effects on health and the environment - photo Ragnar Axelsson (RAX) - Iceland Review.

The beauty of the phenomenon should not obscure the effects on health and the environment - photo Ragnar Axelsson (RAX) - Iceland Review.

Sources :

- Icelandic Met Office

- University of Iceland

- Iceland Review

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