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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
La Palma / Cumbre Vieja - thermal anomalies at the eruptive site and slight incandescence at the 2 fajanas - image Sentinel-2 bands 12,11,4 from 01.12.2021 - One click to enlarge

La Palma / Cumbre Vieja - thermal anomalies at the eruptive site and slight incandescence at the 2 fajanas - image Sentinel-2 bands 12,11,4 from 01.12.2021 - One click to enlarge

The PEVOLCA indicates that activity in the emission sources of the main cone of Cumbre Vieja was sparse and intermittent during the last day and that a new cone formed on the northeast flank, with flows that do not occupy new territory.

Seismicity at intermediate depths continues to increase and is located in the same areas. The number of earthquakes at depths greater than 20 km has also increased. The amplitude of the tremor has also increased.

The island's network of permanent GNSS stations does not show a clear trend in the deformation of the stations closest to the eruptive centers.

In view of the image calibrated at 08:45 UTC on December 1, a vapor column height of 5,200 m is estimated, and an ash cloud of 3,500 m, with a south-southwest direction.
The height of the cone is measured by obtaining a value of 1,127 m. asl.

The air quality remains good and reasonably good. The easterly wind will intensify throughout the day, arranging a plume and a cloud of ash to the south-southwest, a favorable scenario for aeronautical operations.

 

Sources: IGN, DSN

La Palma / Cumbre Vieja - RSAM au 01.12.2021 / 06h15 - Doc. IGN

La Palma / Cumbre Vieja - RSAM au 01.12.2021 / 06h15 - Doc. IGN

Since 4:00 p.m. yesterday, the SAGA seismic station located to the SW of the Sangay volcano has recorded a swarm of earthquakes very similar in shape and characteristics. The number of such earthquakes has increased steadily from 32 events per hour to 60 events per hour at the time of publication of this report. It has also been observed that these events are gaining in amplitude and in the last few hours they have already been large enough to be recorded at regional stations such as PUYO and BULB (Tungurahua).

This type of activity is not frequent in the Sangay volcano, but it has been observed in other volcanoes such as Tungurahua in our country. In these cases, these signals were preferentially associated with the presence of effusive phases in which the appearance and the growth of a volcanic dome could occur; For the moment, no surface activity is observed on the satellite images.

 

Source: IGEPN 02.12.2021

Sangay - seismic swarm recorded at the SAGA station on December 1, 2021 - doc. IGEPN - One click to enlarge

Sangay - seismic swarm recorded at the SAGA station on December 1, 2021 - doc. IGEPN - One click to enlarge

Scientists attached to the UWI Seismic Research Center (UWI-SRC) have completed their mission in Saint Vincent and the Grenadines

Activity on the La Soufrière volcano has declined steadily since the last explosive event of April 22, 2021 and all currently available monitoring data indicates the end of eruptive activity. However, residual vapors at the summit and lahars (mudslides) in the valleys surrounding the volcano will continue to be observed for some time.

The Soufrière Surveillance Unit (SMU) of the National Emergency Management Organization (NEMO) will henceforth assume responsibility for the operations of the Belmont Observatory. Daily monitoring of the volcano will be handled by the UWI-SRC remotely from its base in Trinidad.

The volcanic alert level at La Soufrière remains in YELLOW.

 

Source: UWI-SRC

Soufrière St Vincent - end of the eruptive phase - code yellow - photo UWI-SRC 30.11.2021 - One click to enlarge

Soufrière St Vincent - end of the eruptive phase - code yellow - photo UWI-SRC 30.11.2021 - One click to enlarge

In November 2021, the OVPF recorded in the Piton de la Fournaise massif a total of:
• 113 superficial volcano-tectonic earthquakes (0 to 2.5 km above sea level) below the summit craters;
• 12 deep earthquakes (below sea level);
• 250 collapses (in the Dolomieu Crater, the ramparts of the Fouqué and Piton de Crac enclosures, and the East River).

Volcano-tectonic activity under the Piton de la Fournaise in November 2021 was marked by a seismic crisis on November 17 between 6:12 p.m. (T.U., 10:12 p.m. local time) and 6:26 p.m. (UT, 10:26 p.m. local time), under the summit area. A total of 42 superficial volcano-tectonic earthquakes located under the northern edge of the Dolomieu crater were recorded during this crisis.

No rapid deformation of the ground surface was recorded during this crisis, which means that the magma did not leave the superficial magmatic reservoir. Following this seismic crisis, an increase in seismicity under the summit area was recorded from November 22, with an average of 6 earthquakes per day.

The inflation (swelling) of the building, initiated in April 2021, continued after the intrusion of October 18, 2021 and throughout the month of November 2021. This inflation showed a pressurization of the localized superficial magmatic reservoir around 1.5-2 km deep.

During the period September-November 2021, CO2 emissions tended to gradually decrease, heralding a possible transfer of magma to shallow crustal levels, and in line with the shallow magmatic intrusion of October 18, 2021.

 

Assessment: Throughout the month of November the inflation of the building continued, testifying to the pressurization of the superficial magmatic reservoir (1.5-2 km deep) by the arrival of magma from more deep. The short-lived seismic crisis of November 17, as well as the increase in seismicity since November 22, showed an acceleration of this process at the end of the month.

 

Source: OVPF / monthly bulletin.

Piton de La Fournaise - Illustration of the deformation over 1 year, from December 1, 2020 to December 1, 2021. The baselines are shown here (variation in distance between two GPS receivers) crossing the Piton de la Fournaise building, at the top (top), at the base of the terminal cone (in the middle) and in the far field (at the bottom). 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. Any periods colored in light pink correspond to eruptions. - Doc. OVPF

Piton de La Fournaise - Illustration of the deformation over 1 year, from December 1, 2020 to December 1, 2021. The baselines are shown here (variation in distance between two GPS receivers) crossing the Piton de la Fournaise building, at the top (top), at the base of the terminal cone (in the middle) and in the far field (at the bottom). 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. Any periods colored in light pink correspond to eruptions. - Doc. OVPF

The jökulhlaup, or glacial flood, of the Grímsvötn volcano under the Vatnajökull glacier in southeast Iceland has so far been smaller than expected. Water levels have risen more slowly than during the 2010 floods. The current flooding is expected to peak this weekend.

According to measurements from the Met Office and the University of Iceland, the Grimstvötn ice sheet has sunk a dozen meters so far and 0.175 cubic kilometers of water has already flowed since the start. jökulhlaup, or around 175 billion liters. The flow is currently around 800 cubic meters per second and is expected to increase steadily until the peak, estimated at 4,000 m³ / s at the end of the weekend.

A light white plume overcomes the area of ​​ice cap collapse.

 

Sources: Iceland University, VISIR & RUV

Grimstvötn - vertical displacement of the ice sheet /GPS (left) and discharge in progress (right) - Doc. Un.iceland 01.12.2021 / 16:59 - One click to enlargeGrimstvötn - vertical displacement of the ice sheet /GPS (left) and discharge in progress (right) - Doc. Un.iceland 01.12.2021 / 16:59 - One click to enlarge

Grimstvötn - vertical displacement of the ice sheet /GPS (left) and discharge in progress (right) - Doc. Un.iceland 01.12.2021 / 16:59 - One click to enlarge

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