Overblog
Editer l'article Suivre ce blog Administration + Créer mon blog

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
Gunung Dempo / Sumatra - indovolcano photo - one click to enlarge

Gunung Dempo / Sumatra - indovolcano photo - one click to enlarge

A phreatic explosion took place at Dempo Volcano, Sumatra, at 1:54 a.m. local time on May 31, and produced ashfall in areas within 5 km, including Pagar Alam Utara district (E) and the northern district of Dempo. Ash deposits were as thick as 1 mm. The Alert Level remained at 2 (on a scale of 1 to 4), and the public was reminded to stay 1 km from the crater and up to 2 km on the N flank.
The steam-driven eruption was recorded by the seismic network with a maximum amplitude of 35 mm and a duration of 239 seconds.
Shortly after the eruption, an ash rain of fine particles in the range of 0.5 to 1 mm covered most of the surfaces in the northern districts of Pagar Alam and Dempo about 5 km from the summit.
The alert status remains at level 2. People are advised to avoid 1 km from the crater and 2 km to the north.


Source: Volcano activity update by PVMBG as of June 1, 2022

Bagana - 28.05.2022 - NASA Earth Observatory image by Joshua Stevens, using Landsat OLI / U.S. Geological Survey data - one click to enlarge

Bagana - 28.05.2022 - NASA Earth Observatory image by Joshua Stevens, using Landsat OLI / U.S. Geological Survey data - one click to enlarge

Bagana, one of three volcanoes on the island of Bougainville, was first seen by scientists in the 1840s, ... since then it has erupted almost non-stop. This remote volcano extrudes thick, blocky, slow-moving andesitic lavas. These built the stratovolcano to a height of 1,850 meters (6,000 feet) above sea level. The large symmetrical cone formed over 300 to 500 years, making it one of the youngest and most active volcanoes in the South Pacific.

Since February 2000, Bagana has been in an eruptive state, according to the Smithsonian Global Volcanism Program. Recent lava flows are visible in this image acquired on May 28, 2022 by the Operational Land Imager-2 (OLI-2) on Landsat 9.

Fresh lava is dark brown, while light brown areas have likely been stripped of vegetation by volcanic debris or acid gas. Older lava flows are covered with light green vegetation and the surrounding forests are dark green. The volcanic plume, as well as some nearby clouds, are white.

 

Source: NASA Earth Observatory

Etna - Incandescence at the top of the SEC, and extension of the flow on the flank on 01.06.2022 / 09:50 - image Sentinel-2 bands 12,11,8A - via Mounts Project - one click to enlarge

Etna - Incandescence at the top of the SEC, and extension of the flow on the flank on 01.06.2022 / 09:50 - image Sentinel-2 bands 12,11,8A - via Mounts Project - one click to enlarge

The National Institute of Geophysics and Volcanology, Etneo Observatory, announces that a continuous emission of ash from the SE crater of Etna began from 17:00 GMT on June 1, 2022, forming a volcanic ash plume that affects the SSE sector of the volcano.
In addition, according to an inspection carried out in the afternoon by INGV staff, the effusive activity produced by the SE crater continues, the most advanced lava fronts are around 2100 m.
From the seismic point of view, the average amplitude of the volcanic tremor, while showing a slight decrease from 4:00 p.m. GMT, is currently in the upper range, with a tendency to decrease further. The source of the volcanic tremor is located under the SE crater at an altitude of about 3000 m a.s.l.
Infrasound activity is weak.
With regard to ground deformations, the stations of the GNSS and tilt networks do not show significant variations.

 

Sources: INGV OE, Mirova, Sentinel-2

Etna SEC - 02.06.2022 / 06:39 - therm. webcam. Emct0133 INGV

Etna SEC - 02.06.2022 / 06:39 - therm. webcam. Emct0133 INGV

Etna - tremor at 02.06.2022 / 06h - Doc. INGV OE

Etna - tremor at 02.06.2022 / 06h - Doc. INGV OE

Piton de La Fournaise - Illustration of the deformation over the last six months (the eruptive and intrusive periods are respectively in red and green). The variations in distance between two GPS receivers crossing the Piton de la Fournaise building are shown here, at the top (reference BOMG; top), at the base of the terminal cone (reference FOAG; middle) and in the far field (reference PRAG; bottom) (see location in Figure 5). 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 (© OVPF-IPGP).

Piton de La Fournaise - Illustration of the deformation over the last six months (the eruptive and intrusive periods are respectively in red and green). The variations in distance between two GPS receivers crossing the Piton de la Fournaise building are shown here, at the top (reference BOMG; top), at the base of the terminal cone (reference FOAG; middle) and in the far field (reference PRAG; bottom) (see location in Figure 5). 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 (© OVPF-IPGP).

In April 2022, the OVPF-IPGP recorded at the level of the Piton de la Fournaise massif in total:

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

- No deep earthquakes (below sea level);

- 1222 landslides (in the Cratère Dolomieu, the ramparts of the Enclos Fouqué and the Piton de Crac, and the Rivière de l'Est). The large number of landslides at the level of the broken River of the East was reported to the General Staff of the Zone and Civil Protection of the Indian Ocean so that an aerial reconnaissance by the Air Gendarmerie Section can be made

Seismicity at Piton de la Fournaise was down slightly in April 2022 compared to the previous month with an average of 1.4 superficial volcano-tectonic earthquakes per day (Figures 1 and 2) against around 2.5 earthquakes per day in March. Most of these events were located below the southeast rim of the Dolomieu crater.

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

This recharge process from the depths to the superficial reservoir, located about 1.5-2 km deep, can last several days to several weeks before the roof of the reservoir weakens and breaks, thus giving rise to a 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

Institut de physique du globe de Paris, OVPF 14 RN3 – Km 27 97418 La Plaine des Cafres La Réunion www.ipgp.fr -  twitter : @ObsFournaise -  facebook : ObsVolcanoPitonFournaise  - youtube : Chaîne IPG

Piton de La Fournaise - Sentinel-1 InSAR interferogram between 19 and 31.05.2022 - Via Mounts Project - one click to enlarge

Piton de La Fournaise - Sentinel-1 InSAR interferogram between 19 and 31.05.2022 - Via Mounts Project - one click to enlarge

Commenter cet article

Archives

Articles récents

Hébergé par Overblog