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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

In St Vincent, the surveillance of La Soufrière is reinforced.

A webcam surveillance system was installed at Rose Hall on January 2 to continuously observe the summit of the volcano. A data center has also been created at the Belmont Observatory, to analyze the data collected on the volcano.
The alert level remains at Orange. The volcano continues its effusion activity, and steam can be observed from Belmont.

A flyby by the Nemo on January 3 allows you to see the dome in constant growth. Satellite images taken by Sentinel 2 SWIR and visible Planetlabs clearly reveal its position in the crater.

No evacuation order was issued by NEMO.

 

Sources: UWI and NEMO

Soufrière de St-Vincent - the dome during the flight over on January 3, 2021 - photo NEMO

Soufrière de St-Vincent - the dome during the flight over on January 3, 2021 - photo NEMO

Soufrière de St-Vincent - For comparison, the dome on 12/29/2020 - UWI photo (roughly the same angle)

Soufrière de St-Vincent - For comparison, the dome on 12/29/2020 - UWI photo (roughly the same angle)

Soufrière st Vincent - glow of the dome and its location - image Sentinel-2 SWIR 03.01.2021 / Copernicus via S. Carn - one click to enlarge

Soufrière st Vincent - glow of the dome and its location - image Sentinel-2 SWIR 03.01.2021 / Copernicus via S. Carn - one click to enlarge

An eruptive episode occurred at Sakurajima on January 4 at 4:42 p.m. local time, accompanied by an ash plume 1,000 meters high above the Minamidake crater.

The JMA reports a supply and storage of magma in the underground depths of the Tora caldera (in the inner part of Kagoshima Bay)

Production continues and the amount of volcanic gas (sulfur dioxide) released remains high. Therefore, it is considered that eruption activity will continue to focus on the summit crater of Minamidake.

Volcanic earthquakes are daily (3 January 01, 1 January 2, 1 January 3). Inflation is evidenced by inclinometers and GNSS observation.

Source: JMA

Sakurajima - eruptive episode of January 4, 2021 / 4:42 p.m. loc. - Doc. JMA

Sakurajima - eruptive episode of January 4, 2021 / 4:42 p.m. loc. - Doc. JMA

The month of December 2020 at Piton de La Fournaise will have been marked by an intrusion, on December 4, and an eruption that lasted 26 hours and 35 minutes, from December 7 to 8, on the south-southwest flank of the terminal cone.

The increase in the flow of CO2 in the soil observed following the eruption of October 25-27, 2019, associated with a discontinuous inflation of the building are the witness of a deep recharge of magma and a discontinuous pressurization of the superficial magmatic reservoir. This superficial reservoir pressurization stopped at the end of October 2020 and only resumed a few days before the eruption of December 7-8, 2020. As soon as the eruption ended on December 8, inflation of the terminal cone resumed.

Piton de La Fournaise - eruptive cracks on December 7, 2020 - OVPF photo

Piton de La Fournaise - eruptive cracks on December 7, 2020 - OVPF photo

Piton de La Fournaise - Illustration of the deformation between November 3, 2020 and January 3, 2021. The baselines (variation in distance between two GPS receivers) crossing the Piton de la Fournaise building, at the top (in top), at the base of the terminal cone (in the middle) and in the far field (in the bottom). An increase is synonymous with elongation and therefore swelling of the volcano; conversely, a decrease is synonymous with contraction and therefore deflation of the volcano. The possible periods colored in light pink correspond to the eruptions. - Doc. OVPF

Piton de La Fournaise - Illustration of the deformation between November 3, 2020 and January 3, 2021. The baselines (variation in distance between two GPS receivers) crossing the Piton de la Fournaise building, at the top (in top), at the base of the terminal cone (in the middle) and in the far field (in the bottom). An increase is synonymous with elongation and therefore swelling of the volcano; conversely, a decrease is synonymous with contraction and therefore deflation of the volcano. The possible periods colored in light pink correspond to the eruptions. - Doc. OVPF

The volcano-tectonic activity under the Piton de la Fournaise in December 2020 will have been mainly marked by two seismic crises (on December 4 and 7) accompanying an intrusion (on the 4th), and preceding an eruption on the 7th with respectively 118 and 498 earthquakes. summits on December 4 and 7. These seismic crises were preceded by a slight resumption of the summit seismicity on December 3 (3 earthquakes). The first seismic crisis of December 4 (started at 5:10 a.m. local time), accompanied by deformations, did not result in surface activity but testified to an intrusion of magma towards the surface.

Following this crisis, the seismicity remained high, prefiguring the crisis of December 7 (2:28 a.m. local time; 10:28 p.m. on December 6 in UTC time). This second crisis, accompanied by deformations much larger than those of December 4, was followed 2 hours and 12 minutes after its onset by the arrival of an eruptive tremor (4:40 local time), indicating the migration of magma near the surface. This eruption lasted 26 hours and 35 minutes on the south-southwest flank of the terminal cone, until the eruptive tremor stopped on December 8 at 7.15 am local time (3.15 am UT). Following the end of the eruption on December 8, summit volcano-tectonic activity continued, with an average of two superficial volcano-tectonic earthquakes per day below the summit craters recorded between December 8 and 23. Subsequently, only two superficial volcano-tectonic earthquakes were recorded between December 24 and 31.

 

Source: OVPF - Monthly bulletin December 2020

Piton de La Fournaise -: Map of the ground displacements associated with the injection of magma towards the surface which led to the eruption of December 7-8, 2020. The vectors represent the horizontal displacements (max = 0.3 m) and the colored circles vertical displacements (scale given by the color bar, max = 0.35 m). The red lines represent the location of the eruptive cracks (© OVPF-IPGP)

Piton de La Fournaise -: Map of the ground displacements associated with the injection of magma towards the surface which led to the eruption of December 7-8, 2020. The vectors represent the horizontal displacements (max = 0.3 m) and the colored circles vertical displacements (scale given by the color bar, max = 0.35 m). The red lines represent the location of the eruptive cracks (© OVPF-IPGP)

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