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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
2021.09.20 La Palma - Doc. Sentinel-2 via Copernicus / EU 20.09.2021 - one click to enlarge

2021.09.20 La Palma - Doc. Sentinel-2 via Copernicus / EU 20.09.2021 - one click to enlarge

 La Palma - Image therm Flir21.09.2021  - InVolcan

La Palma - Image therm Flir21.09.2021 - InVolcan

The Cumbre Vieja / La Palma eruption continues with lava fountains from the new vent that opened on September 20 and a continuous lava flow emission. In the last few hours, the volcanic tremor has increased significantly, suggesting that the rate of exit has increased or that something else is changing.

La Palma - RSAM at 09.21.2021 around 18h - Doc. InVolcano

La Palma - RSAM at 09.21.2021 around 18h - Doc. InVolcano

Situation during the day of September 21:

The lava flow continues inexorably to advance towards the coastal area of ​​LaPalma Island. During the last hours, there has been a division of the flow into several arms due to the topography of the land (less slope ... widening of the flows). The flows advance slowly, destroying Todoque.

destroyed 166 buildings and covered around 106 hectares of land at the start of the day. The speed at which it advances has remained roughly constant at 300 meters per hour.

La Palma - The area affected by the lava flows reaches 154 hectares (source Copernicus EMS - 22.09.2021) - click to enlarge

La Palma - The area affected by the lava flows reaches 154 hectares (source Copernicus EMS - 22.09.2021) - click to enlarge

Inflation continued and reached 30 cm in places, a sign that the magma continues to pressurize and accumulate underground.

Other vents, perhaps further north, could open.

This is also shown by the continued seismic activity. Although much weaker than before the eruption, it remains significant. In the last 24 hours, there have been 3 earthquakes of magnitude 3.0 to 3.8 and 12 earthquakes between 2.0 and 2.9.

In the early evening, the evacuation of La Laguna was decided, depending on the advance of the lava and the possibility of opening new vents.

La Palma - Sentinel-1 ascending track interferogram, Sep 14-20, 2021 - Doc. Mounts Project

La Palma - Sentinel-1 ascending track interferogram, Sep 14-20, 2021 - Doc. Mounts Project

The DSN / Department of National Security informed us this September 22 at 8 a.m., that during the evening and night, the eruptive activity remained concentrated on 4 of the new mouths. The lava flows towards the coast continue in 2 main languages: the northern branch advances at 120 meters / hour and affects the locality of Todoque; the southern branch shows almost no movement.

Activity increased noticeably from the second vent that opened the day before and quickly became the main one.
Lava fountains several hundred meters high; we observe the explosion of large lava bubbles and an increase in the sound level of the eruption.

The surface affected by the lava flows reaches 154 hectares (source: Copernicus EMS).

The often asked question of the duration of such an eruption offers no answer ... However, InVolcan has established an average duration for the historical eruptions of the various volcanoes of the Cumbre Vieja system.

 

Sources : InVolcan, DSN, Copernicus, Mirova, Mounts Project, local media.

LaPalma - thermal anomalies at 22.09.2021 / 03:45 - the anomalies can be masked or attenuated by clouds - Doc. Mirova_MODIS_Latest10NTI

LaPalma - thermal anomalies at 22.09.2021 / 03:45 - the anomalies can be masked or attenuated by clouds - Doc. Mirova_MODIS_Latest10NTI

La Palma - average duration of volcanic eruptions in the Cumbre Vieja system - Doc. Instituto Volcanológico de Canarias / 22.09.2021

La Palma - average duration of volcanic eruptions in the Cumbre Vieja system - Doc. Instituto Volcanológico de Canarias / 22.09.2021

Ash emissions have decreased in frequency and intensity over the past 24 hours at Semisopochnoi, with distinct ash clouds currently drifting northwest between 3,000 and 4,500 meters.

Due to this drop in activity, the Alaska Volcano Observatory has lowered the color code from Aviation / Volcano Alert Level to Orange / Watch.

SO2 emissions have also been observed during the last 24 hours drifting north of the island. Seismicity remained high with explosions detected in seismic and infrasound networks.

Small eruptions producing minor ash deposits near the active northern crater of Mount Cerberus and ash clouds typically less than 3,000 meters above sea level have characterized recent activity, which shows no sign of slowing down.

 

Source: AVO

Semisopochnoi - SO2 emissions - Tropomi image 20.09.2021 / 00:47 UTC- Doc. AVO / Matt Loewen - one click to enlarge

Semisopochnoi - SO2 emissions - Tropomi image 20.09.2021 / 00:47 UTC- Doc. AVO / Matt Loewen - one click to enlarge

Strong northwest winds near Katmai and the Valley of Ten Thousand Smokes picked up loose volcanic ash, which erupted during the Novarupta-Katmai eruption of 1912, and carried it southeast into towards Kodiak Island early this September 21 in the morning.

The National Weather Service issued a SIGMET for this low level event and suggests the maximum cloud height is 2,500 meters above sea level.

This phenomenon is not the result of recent volcanic activity and occurs during periods of high winds and dry, snowless conditions in the Katmai region and other young volcanic areas of Alaska.

No eruption is in progress. All the volcanoes in the Katmai region (Snowy, Griggs, Katmai, Novarupta, Trident, Mageik, Martin) remain in the GREEN color code.

 

Source: AVO

Remobilization of the ashes of the Katmai - Doc. USGS - AVO 09.21.2021 / 11:48 AKDT - one click to enlarge

Remobilization of the ashes of the Katmai - Doc. USGS - AVO 09.21.2021 / 11:48 AKDT - one click to enlarge

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