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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 - 03/17/2021 / 11:52 p.m. - photo PGN Ngepos / PVMBG

Merapi - 03/17/2021 / 11:52 p.m. - photo PGN Ngepos / PVMBG

The activity of Merapi, on Java, is continuous and characterized by numerous avalanches, particularly visible at night. The level remains at 3 / siaga.

The seismicity of March 17 is characterized by:

- 1 earthquake marking a pyroclastic flow
- 195 collapse / avalanche earthquakes
- 8 blast / emission earthquakes
- 6 hybrid / multiphase earthquakes
- 2 deep tectonic earthquakes.

 

Sources: PVMBG, Magma Indonesia and BPPTKG

Merapi - seismicity at 17.03.2021 - Doc. BPPTKG

Merapi - seismicity at 17.03.2021 - Doc. BPPTKG

The Ibu, in the northern Molluques, in continuous eruption since April 2008, experienced an eruptive episode on March 17, 2021, marked by a plume of gas and ash 200-800 meters above the summit.

The seismicity of March 17 is characterized by:

- 71 eruption earthquakes
- 79 collapse / avalanche earthquakes
- 37 emission earthquakes
- 60 harmonic earthquakes
- 1 low frequency earthquake
- 2 deep volcanic earthquakes
- 12 distant tectonic earthquakes

Its activity level remains at 2 / waspada, with advice for the community around G. Ibu and visitors / tourists not to practice activities within a radius of 2.0 km and 3.5 km towards the opening of the crater in the northern part of the active crater.

 

Source: PVMBG

IBU - 03.17.2021 / 5:59 p.m. WIB - PVMBG / Magma Indonesia

IBU - 03.17.2021 / 5:59 p.m. WIB - PVMBG / Magma Indonesia

Since March 13, a resumption of seismicity has been observed under the Piton de la Fournaise.

Between March 13 and 17, 20 volcano-tectonic earthquakes, of magnitude less than 1, were recorded and located under the eastern part of the Dolomieu crater between 0.3 and 0.9 km above sea level (ie between 1.6 and 2.2 deep).

Piton de La Fournaise - Histogram representing the number of superficial volcano-tectonic earthquakes recorded between January 1 and March 17, 2021 (© OVPF-IPGP).

Piton de La Fournaise - Histogram representing the number of superficial volcano-tectonic earthquakes recorded between January 1 and March 17, 2021 (© OVPF-IPGP).

This seismicity is accompanied by a resumption of inflation (swelling) of the top of the Piton de la Fournaise building. This building inflation remains very low for the moment and will have to be confirmed over time in the coming days.

This seismicity and deformation are synonymous with a pressurization of the superficial magmatic reservoir located about 2-2.5 km below the summit.

This resumption of seismicity follows a change in the composition of fumarole emissions recorded at the top of Piton de la Fournaise at the end of February 2021 (presence of small quantities of SO2, coupled with CO2) and an increase in CO2 fluxes in the soil. in March 2021, especially on the sides of the volcano in the far field (Plaine des Cafres and Plaine des Palmistes sectors). Since CO2 is the first gas to be released from magma at great depth (from the mantle), its detection in the far field is often associated with a deep rise of magma.

 

This recharging process from the depths to the shallow reservoir can take several days to several weeks before the reservoir roof weakens and breaks, resulting in an injection of magma to the surface and an eruption, but can also stop without giving rise to an eruption in the short term.

The most recent eruption, which lasted only 24 hours, occurred on December 7, 2020.

 

Source: OVPF

Piton de La Fournaise - the Dolomieu crater - in the background, the summit of Piton des Neiges - photo archives © Bernard Duyck

Piton de La Fournaise - the Dolomieu crater - in the background, the summit of Piton des Neiges - photo archives © Bernard Duyck

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