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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 : #volcanic activity
Merapi - activity between March 25 and 31, 2022 -Doc. PVMBG - BPPTKG

Merapi - activity between March 25 and 31, 2022 -Doc. PVMBG - BPPTKG

During the week of March 25 to 31, 2022 at Merapi, there were 2 pyroclastic avalanche flows towards the southwest with a sliding distance of 2,500 m. Lava block avalanches were observed 118 times towards the southwest, dominating the Bebeng River with a maximum slip distance of 2,000 m.

On the south-west dome we observe that the height increases by about 4 m. For the middle dome, no significant morphological change was observed. According to photo analysis, the volume of the southwest lava dome is 1,672,000 m³ and the central dome is 2,582,000 m³.

The intensity of seismicity this week is still quite high. Mount Merapi's deformation, which was monitored using EDM this week, showed a distance shortening rate of 0.3 cm/day.

Merapi - seismicity and displacement between 25 and 31.03.2022 - Doc. BPPTKG

Merapi - seismicity and displacement between 25 and 31.03.2022 - Doc. BPPTKG

The pyroclastic flow of Merapi on April 1, 2022 at 3:00 p.m. WIB was recorded on a seismogram with an amplitude of 35 mm and a duration of 94 seconds. Visually obscured by fog, it moved an estimated distance of 1,500 m to the southwest.

Activity of Merapi, Piton de La Fournaise and Great Sitkin.

The activity status is set at level 3 /siaga.

The current potential danger consists of lava avalanches and hot clouds in the south-southwest sector covering the Boyong River for a maximum of 5 km, the Bedog River, Krasak, Bebeng for a maximum of 7 km. The southeast sector covers the Woro River for a maximum of 3 km and the Gendol River for a maximum of 5 km. Meanwhile, the ejection of volcanic material in the event of an explosive eruption can reach a radius of 3 km from the summit.

 
Source: BPPTKG

Piton de La Fournaise - east face of Dolomieu crater  - photo archives archives © Bernard Duyck - one click to enlarge

Piton de La Fournaise - east face of Dolomieu crater - photo archives archives © Bernard Duyck - one click to enlarge

At Piton de La Fournaise, seismicity during the month of March 2022 was up slightly compared to February 2022 with an average of 2.5 superficial volcano-tectonic earthquakes per day against an average of 2 earthquakes per day in February .

Most of these events were located under the eastern rim of the Dolomieu crater.

The OVPF recorded at the level of the Piton de la Fournaise massif in total:

- 77 superficial volcano-tectonic earthquakes (0 to 2.5 km above sea level) under the summit craters;

- 737 collapses (in the Cratère Dolomieu, the ramparts of the Enclos Fouqué and the Piton de Crac, and the Rivière de l'Est).

Piton de La Fournaise: Illustration of the deformation over the last six months (the eruptive and intrusive periods are respectively in red and green). Here are represented the variations in distance between two GPS receivers crossing the Piton de la Fournaise building, at the top, at the base of the terminal cone and in the far field. A rise is synonymous with elongation and therefore swelling of the volcano; conversely a decrease is synonymous with contraction and therefore deflation of the volcano (© OVPFIPGP).

Piton de La Fournaise: Illustration of the deformation over the last six months (the eruptive and intrusive periods are respectively in red and green). Here are represented the variations in distance between two GPS receivers crossing the Piton de la Fournaise building, at the top, at the base of the terminal cone and in the far field. A rise is synonymous with elongation and therefore swelling of the volcano; conversely a decrease is synonymous with contraction and therefore deflation of the volcano (© OVPFIPGP).

The inflation which continued throughout the month of March, as well as the increase in seismicity and CO2 fluxes in the ground, witnessed a replenishment and a pressurization of the superficial magmatic reservoir by upwellings of deep fluids.


This process of recharge from the depths to the superficial reservoir can take several days to several weeks before the roof of the reservoir weakens and ruptures, thus allowing injection of magma towards the surface and an eruption, but can also stop without giving rise to an eruption in the short term.


Source: OVPF monthly bulletin.

Find all the information relating to the activity of Piton de la Fournaise on the various OVPF-IPGP media:

- the website: ipgp.fr/fr/ovpf/actualites-ovpf

- the Twitter account: twitter.com/obsfournaise

- the Facebook account: http://facebook.com/ObsVolcanoPitonFournaise

Great Sitkin - photo archives AVO / 11.2021 - one click to enlarge

Great Sitkin - photo archives AVO / 11.2021 - one click to enlarge

Evidence of lava effusion from a vent in the summit crater of Great Sitkin Volcano was last seen in satellite radar data on March 24, but slow effusion has likely continued since then. The erupting lava has overshot the rim of the summit crater and is flowing into small valleys on the southern, western and northern flanks of the volcano. Clouds have obscured most views of the volcano over the past week and seismic activity remains low.

The terrain is steep near the terminus of the lava flow lobes, and blocks of lava could break off without warning and form small rock avalanches in these valleys. These avalanches can release ash and gas and travel several hundred meters beyond the lava flows; they would be dangerous to anyone in those areas.

The Great Sitkin is monitored by local seismic and infrasound sensors, satellite data, web cameras, and remote infrasound and lightning networks.

Current volcanic alert level: Watch
Current Aviation Color Code: Orange

 

Source: AVO

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