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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
 Pacaya - imageSentinel-2 bands 12,11,8A from 01.29.2021 via Mounts project

Pacaya - imageSentinel-2 bands 12,11,8A from 01.29.2021 via Mounts project

Pacaya - Thermal anomalies at the summit and on the lava flow - image Sentinel-2 bands12,11,5 du 29.01.2021 - Insivumeh

Pacaya - Thermal anomalies at the summit and on the lava flow - image Sentinel-2 bands12,11,5 du 29.01.2021 - Insivumeh

Pacaya - thermal anomalies at 01.02.2021 / 04:25 - Doc. Mirova_MODIS_logVRP

Pacaya - thermal anomalies at 01.02.2021 / 04:25 - Doc. Mirova_MODIS_logVRP

In the Pacaya, explosions, of varying level, follow one another and generate plumes of ash at 100-150 m. above the crater, dispersing westward for about 10 kilometers.

The flow on the southern flank measures on January 31 a length of 900 meters. Avalanches from the lava front reach 1,200 meters.

The tremor continues to be recorded, in connection with the ascent of magma, the movements of the lava flow and the pressure of the gases.

 

Source: Insivumeh

Reykjanes Peninsula - Grindavík with Mount Þorbjörn in the background - photo mbl.is / Kristinn Magnússon

Reykjanes Peninsula - Grindavík with Mount Þorbjörn in the background - photo mbl.is / Kristinn Magnússon

Some parts of Iceland shake more than others, and last year a total of 22,000 tremors were recorded on the Reykjanes Peninsula in southwest Iceland. Most of them had a magnitude less than 3.

Most activity has been concentrated in the area from the southwestern tip of Reykjanes to Lake Kleifarvatn in the east, but in recent months the activity and source of the tremors has shifted more to the east, towards Krýsuvík. On October 20 of last year, the source of a magnitude 5.6 earthquake was not far from Lake Djúpavatn.

The Reykjanes Ridge tectonic plate boundary stretches from west to east across the Reykjanes Peninsula. This is where the North American tectonic plate meets the Eurasian one.

On average, the plates are moving away from each other by about one cm per year, but in recent semesters movement in some areas of Reykjanes has reached 16 cm.

Kristín Jónsdóttir, earthquake hazards coordinator at the Icelandic Met Office, assumes that the pressure that builds up in the earth, between Lake Kleifarvatn and the Bláfjöll mountains, can only be released during a large earthquake. Two of them, magnitude 6.3 and 6, occurred in 1929 and 1968. Their source was near the Brennisteinsfjöll mountains, east of Lake Kleifarvatn.

Björn Oddsson, a geophysicist and program director in the Department of Civil Protection and Emergency Management, says the Reykjanes Peninsula is under constant surveillance. An uncertainty phase (the lowest alert phase) will remain there while the seismic activity is above average.

 

Source: Iceland Monitor

Reykjanes Peninsula - gauge between the North American and Eurasian tectonic plates - photo archives © Bernard Duyck

Reykjanes Peninsula - gauge between the North American and Eurasian tectonic plates - photo archives © Bernard Duyck

La Palma - the volcanic chain Cumbre Vieja - Fotoaereasdecanarias

La Palma - the volcanic chain Cumbre Vieja - Fotoaereasdecanarias

Since 04:11 (Canary Island time) on January 31, 2021, the Canary Islands seismic network operated by the Canary Islands Volcanological Institute (INVOLCAN) has been recording a new swarm of small-magnitude seismic events under the volcano Cumbre Vieja / La Palma

Among the many seismic events detected, 38 of them were located by the seismic network of the Canary Islands on La Palma until 11:02 am (Canary Island time) on January 31, 2021. The hypocenters fall under the western slope of the Cumbre Vieja volcano at depths between 15 and 20 km. The maximum magnitude observed was 1.8.

This new seismic swarm poses no danger to residents and visitors to La Palma given the low magnitude and depth of the earthquakes.

In the short and medium term, no significant change in volcanic activity is expected in Cumbre Vieja, which since 2017 has experienced 8 seismic swarms, including the one that started on January 31, 2021 (1 in 2017, 1 in 2018, 5 in 2020 and 1 in 2021).

In recent years, no significant horizontal and vertical displacement has been recorded via the Canary Islands GPS network in La Palma

Regarding the geochemical program for monitoring the volcanic activity of Cumbre Vieja, it is worth highlighting the observation of significant changes in the diffuse emission of hydrogen into the atmosphere by the Cumbre Vieja volcano linked to recent seismic swarms, as well as 'an increasing trend in the diffuse flux of carbon dioxide at the LP04 geochemical station.

 

Source: InVolcan

La Palma - seismic swarm at 31.01.2021 - Doc. InVolcano

La Palma - seismic swarm at 31.01.2021 - Doc. InVolcano

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