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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, #Sismologia
Etna - SEC lava flow on 18.05.2022 - Doc. Cam therm FLIR / INGV OE

Etna - SEC lava flow on 18.05.2022 - Doc. Cam therm FLIR / INGV OE

Etna - Situation of summit activity on 17.05.2022 - Doc. INGV Vulcani (Doc. above) -- Etna - image Sentinel-2 bands 12,11,8A on 19.05.2022 / 09:40 - Via Mounts project (image below) - click to enlarge
Etna - Situation of summit activity on 17.05.2022 - Doc. INGV Vulcani (Doc. above) -- Etna - image Sentinel-2 bands 12,11,8A on 19.05.2022 / 09:40 - Via Mounts project (image below) - click to enlarge

Etna - Situation of summit activity on 17.05.2022 - Doc. INGV Vulcani (Doc. above) -- Etna - image Sentinel-2 bands 12,11,8A on 19.05.2022 / 09:40 - Via Mounts project (image below) - click to enlarge

The National Institute of Geophysics and Volcanology announces that after the opening of an effusive vent on the northern flank of the Southeast Crater of Etna, communicated on 05/12/2022 at 8:38 p.m. local time, placed at a altitude of about 3250 m a.s.l.

The effusive activity stabilized in the following days, producing a lava flow which develops towards the ENE in the Valle del Leone desert whose most advanced front has currently reached an altitude between 2400 and 2300 m a.s.l. The new lava flow from the flank of the southeast crater of Etna flanks the one already in progress which formed around 3250 m.

At the same time, the SE crater is affected by a discontinuous Strombolian explosive activity of variable intensity which, in the most intense phases, produces a modest emission of ash which is rapidly diluted in the atmosphere.
From a seismic point of view, compared to the 12 cm press release, the trend of the gradual increase in the average amplitude of the tremor continues in the range of high values.

The sources of the tremor are located in the Southeast crater around 3000 m. above sea level.

 

Source: INGV – extraordinary press release 18.05.2022 & INGV Vulcani

Etna - tremor, variations on 20.05.2022 / 05h - Doc. INGV

Etna - tremor, variations on 20.05.2022 / 05h - Doc. INGV

The Svartsengi seismic swarm on the Reykjanes peninsula is still ongoing.

Yesterday (May 19), around 370 earthquakes were detected in the region, the largest a M3.0 at 11.35am. The greatest seismic activity is now north of Grindavík.
Land inflation around Svartsengi and Þorbjörn has reached 4 centimeters in recent weeks, as evidenced by a latest interferogram.
Landslides can occur on the slopes and sides of mountains when earthquakes of these magnitudes occur. Caution is advised for people in these areas.

 

Source: Orapuls

Grindavik / Svartsengi - deformation - interferogram between 9 and 19.05.2022 - Doc. IMO

Grindavik / Svartsengi - deformation - interferogram between 9 and 19.05.2022 - Doc. IMO

Large volcanic eruptions are often preceded by detectable manifestations, such as seismicity, gas emissions, or variations in the level of ambient volcanic activity. The detection of these changes is therefore valuable for anticipating the hazard and the volcanic risk. Nevertheless, these manifestations are difficult or even impossible to measure for volcanoes that are difficult to access.

This is the case of Nyiragongo, in the Democratic Republic of Congo, whose eruptions have devastated the city and the region of Goma on several occasions in the past, until recently in May 2021.

Barrière et al. [2022] use satellite imagery, mainly radar, to continuously measure the oscillations of the lava lake that fills the summit crater of Nyiragongo, and the rates of lava effusion over time. These rates and the lake level are found to be correlated with seismic activity, demonstrating that they are the manifestation of changes in the dynamics and pressurization of the magmatic system at depth. This work thus demonstrates the importance of satellite data for detecting and anticipating volcanic eruptions at Nyiragongo and other volcanoes in the world.

 

Sources: Barrière, J., Nicolas d'Oreye, , Smets, B., Oth, A., Delhaye, L., Subira, J., et al. (2022). Intra-crater eruption dynamics at Nyiragongo (D.R. Congo), 2002–2021. Journal of Geophysical Research: Solid Earth, 127, e2021JB023858. https://doi.org/10.1029/2021JB023858

—Michael Poland, Associate Editor, Journal of Geophysical Research: Solid Earth; translation by Isabelle Manighetti, Editor in Chief, JGR: Solid Earth

Nyiragongo lake level over time. (a) View of the Nyiragongo volcano and its summit crater where the lava lake extends (photos taken by the Volcanological Observatory of Goma, in November 2013 on the left and in April 2014 on the right). (b) Variation in the altitude of the lava lake (in meters above sea level) over time, measured occasionally in the field between 1948 and 2020, and continuously by radar satellite since 2006 (red line) . Lake and crater level changes are linked to eruptive activity, with major subsidence during the 1977, 2002, and 2021 eruptions. The 2021 eruption, however, was preceded by a rise in the lake level, suggesting a pressurization of the magmatic system at depth. Credit: Barrière et al. [2022]

Nyiragongo lake level over time. (a) View of the Nyiragongo volcano and its summit crater where the lava lake extends (photos taken by the Volcanological Observatory of Goma, in November 2013 on the left and in April 2014 on the right). (b) Variation in the altitude of the lava lake (in meters above sea level) over time, measured occasionally in the field between 1948 and 2020, and continuously by radar satellite since 2006 (red line) . Lake and crater level changes are linked to eruptive activity, with major subsidence during the 1977, 2002, and 2021 eruptions. The 2021 eruption, however, was preceded by a rise in the lake level, suggesting a pressurization of the magmatic system at depth. Credit: Barrière et al. [2022]

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