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Earth of fire

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

Publié le par Bernard Duyck
Publié dans : #Actualités volcaniques
 Destabilization of the flanks of volcanoes on Reunion Island - Doc.Oehler069

Destabilization of the flanks of volcanoes on Reunion Island - Doc.Oehler069

Le Piton de La Fournaise under all its facets.


A large-scale electric tomography mission will take place on Piton de la Fournaise between May 2 and 21, 2017, with the aim of imaging the surface structure of the building up to 900 meters deep to understand the risks associated with a potential slip.
This is the first time that the protocol will be tested in France: it has been tested once only on Etna, in Sicily, during the year 2015. A real challenge according to Aline Peltier, director of the Volcanological Observatory. .. it will be necessary to extend on the ground cables to allow 2D imaging, via electrodes spaced 60 meters apart. It will inject current that will be recovered, testifying to the resistance of the rock.
Following successive intrusions, the eastern part of the volcano is destabilized and tends to slip by two centimeters per year. Is this slippage linked to a profound destabilization of the structure?
"It's important to understand the risks associated with potential slippage, as happened in the past, 4,500 years ago," recalls the director in an interview with Imazpress. A risk that would often be "ignored" in a context of "island volcanism", as is the case on the island.


Source: Imazpress

Piton de la Fournaise - the eruptive site on 22.02.2017 - photo OVPF

Piton de la Fournaise - the eruptive site on 22.02.2017 - photo OVPF

The name of the cone formed during the last eruption.


This cone was named Piton Timize on April 30th ... in reference to the name given by the inhabitants of Grand Bassin to Bourbon black petrel, or Fouquet noir / Pseudobulweria aterrima, whose breeding grounds have recently been updated, and classified as Critically Endangered.

The symbolism is important, the eruption being completed at the time of the flight of the game, black petrels leaving the breeding colonies to venture out to sea.


Provided by: Clicanoo

Bourbon black petrel - photo Fabien JAN -SEOR / FabKacau / CC BY-SA 3.0

Bourbon black petrel - photo Fabien JAN -SEOR / FabKacau / CC BY-SA 3.0

OVPF Monthly Bulletin / 02.05.2017


Seismicity
In April 2017, the OVPF registered a total of:
- 32 superficial volcano-tectonic earthquakes (0-2 km deep) under the summit craters;
- 4 deep earthquakes (> 2 km deep);
- 343 collapses (in the Crater Dolomieu and at the level of the ramparts of the Enclosed Fences);
- 22 local earthquakes (under the island, Piton des Neiges side);
- 2 regional earthquakes (in the Indian Ocean area).


Deformation
Following the lull observed in March, inflation (swelling) of the building resumed in April, but at a lower rate than those observed in 2015-2016 and early 2017 (elongation of 0.1-0.2 mm Per day between stations in the summit zone, compared with 0.5-1 mm during previous inflation periods.


Gas Geochemistry
At the level of the summit zone, excesses with respect to the CO2, H2S and SO2 atmosphere remain globally low.
The CO2 concentrations in the soil measured at the remote stations of the Plaine des Cafres and at the level of the Gîte du volcan show an increase since 28 March.

Note: While concentrations of sulfur species (H2S, SO2) at the top of the volcano remain very low, there has been a marked increase in CO2 concentrations diffused by the soil since the end of March 2017. The increase is detected at the same time In the distal sector (Plaine des Cafres) and near (Gîte du volcan). It should be noted that following the eruption of February 2017, concentrations in the distal sector returned to baseline levels, which was not the case for concentrations in the near sector.

Piton de La Fournaise - Illustration of the distortion during the last twelve months (eruptions of 26-27 May, 11-18 September 2016 and 31 January-27 February 2017 are shown in yellow). Here is shown a baseline (distance between two GPS receivers) crossing the Dolomieu crater from north to south (in black the raw data, in blue the smoothed data over a week). A rise is synonymous with elongation and therefore swelling of the volcano; Conversely, a decrease is synonymous with contraction and therefore with deflation of the volcano. (© OVPF / IPGP)

Piton de La Fournaise - Illustration of the distortion during the last twelve months (eruptions of 26-27 May, 11-18 September 2016 and 31 January-27 February 2017 are shown in yellow). Here is shown a baseline (distance between two GPS receivers) crossing the Dolomieu crater from north to south (in black the raw data, in blue the smoothed data over a week). A rise is synonymous with elongation and therefore swelling of the volcano; Conversely, a decrease is synonymous with contraction and therefore with deflation of the volcano. (© OVPF / IPGP)

Piton de La Fournaise - Concentration of CO2 in the soil at the level of the volcano deposit between April 2016 and April 2017 (eruptions of 26-27 May, 11-18 September 2016 and 31 January-27 February 2017 are shown in red ). In blue the raw data, in red the corrected data of the effects of temperature. Values are normalized to the maximum value. (© OVPF / IPGP)

Piton de La Fournaise - Concentration of CO2 in the soil at the level of the volcano deposit between April 2016 and April 2017 (eruptions of 26-27 May, 11-18 September 2016 and 31 January-27 February 2017 are shown in red ). In blue the raw data, in red the corrected data of the effects of temperature. Values are normalized to the maximum value. (© OVPF / IPGP)

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