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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 - 01.10.2021 - morning lava flows - photo InVolcan

La Palma / Cumbre Vieja - 01.10.2021 - morning lava flows - photo InVolcan

At Cumbre Vieja, the cone morphology above the original eruptive fissure shows signs of increasing instability, with several new effusive vents opening in the past 12 hours or so.
At 10:15 a.m. local time on October 1, 2021, on-site observers reported seeing new gas and ash emerge from what is likely another vent forming at the northwest base of the cone.

A new lava flow follows a different course, and could damage an area slightly north of the older flows (Paraiso region).

La Palma / Cumbre Vieja - lava flows at 30.09.2021 - Doc.Copernicus EMSR / Airbus Space Pleiades VHR image

La Palma / Cumbre Vieja - lava flows at 30.09.2021 - Doc.Copernicus EMSR / Airbus Space Pleiades VHR image

According to the latest EMRS / Copernicus survey of September 30, the area covered with lava is 258 ha, and the number of destroyed houses reached 870 (provisional data: 1005 according to RTVC on October 1).


The lava delta at the entrance to the ocean on the west coast of La Palma is growing surprisingly fast. This bathymetric map (@UdriGeo) specifies the situation.
Once the delta expands further west, it will rest on steeper submarine slopes and the risk of gravitational collapse will increase. Collapses of this type are very dangerous because they usually set off strong explosions, large plumes of acid vapor and could even be responsible for small local tsunamis.

La Palma / Cumbre Vieja - advance of the dela flow and bathymetry of the coast - Doc. @UdriGeo - geologist 09.30.2021

La Palma / Cumbre Vieja - advance of the dela flow and bathymetry of the coast - Doc. @UdriGeo - geologist 09.30.2021

Creation of a lava delta and its collapse - diagrams via USGS- HVO / Johnson, Jenda. Public domain - one click to enlargeCreation of a lava delta and its collapse - diagrams via USGS- HVO / Johnson, Jenda. Public domain - one click to enlarge

Creation of a lava delta and its collapse - diagrams via USGS- HVO / Johnson, Jenda. Public domain - one click to enlarge

La Palma / Cumbre Vieja - work of volcanologists in the field - doc. IGNes

La Palma / Cumbre Vieja - work of volcanologists in the field - doc. IGNes

In the past 24 hours, 12 earthquakes have been located in the southern area of ​​La Palma, near the ongoing volcanic eruption. As in previous days, the hypocenters are located between 10 and 14 km deep in the same area where the reactivation began on September 11.

The average amplitude of the volcanic tremor remained stable yesterday morning within a range of average values ​​for this eruption. From 18 UTC yesterday, it started to gradually increase until it reached values ​​similar to those it reached during the first two days of the eruption (September 19-20).

The island's network of permanent GNSS stations shows a return to deformation stability.

 

First petrographic results of samples from the beginning of the La Palma eruption, analyzed by the Vulcanismo Group @ unicomplutense @ urjc, in collaboration with @ IGME1849: the rock is an amphibole pyroxene tephritis.

 

Sources: IGNes, Copernicus EMSR, RTVC, UdriGeo, USGS (lava entering ocean), Facultad de Ciencias Geologicas.

La Palma - October 1, 2021 - Observation by drone of a view of the path of the active lava flows and details of the progress of the new flow - Doc. Instituto Geológico y Minero de España

The INGV has observed a significant change linked to the hydrothermal activity that feeds the fumaroles of La Fossa crater, on the island of Vulcano in the Aeolian Islands.

The fumarole activity has varied considerably, in particular the temperature of the gases emitted by these fumaroles has increased constantly over time. To this must be added an increase in microseismicity, that is to say small local earthquakes and an increase in the emission of carbon dioxide and sulfur dioxide, namely the two main gases emitted by volcanic systems after water vapor.

The Etneo observatory has installed new seismic stations to complement those existing on the island, also preparing the installation of a thermal camera which frames the fumarole zone of the crater. In addition, for about two months, the Palermo section of the INGV has activated 4 new stations in the city of Vulcano Porto to measure the flow of CO2 from the soil and the concentration of CO2 in the air.

Following a meeting between civil protection and the Major Risks Commission, the volcanic alert level changed from green (Base) to yellow (Attention).
Access to the summit crater of the Fosse has been totally prohibited to the public.

 

Source: INGV OE

Vulcano, from Lipari - photo Marco Pistolesi 30.09.2021

Vulcano, from Lipari - photo Marco Pistolesi 30.09.2021

Vulcano - fumaroles in the crater of La Fossa - photo Marco Anzidei 30.09.2021

Vulcano - fumaroles in the crater of La Fossa - photo Marco Anzidei 30.09.2021

In recent weeks, Whakaari / White Island has gone through an active phase, with increased gas emissions and minor volcanic earthquakes. The magma moved to shallower levels, which has since degassed, feeding high-energy gases and vapor-rich vents. These vents intermittently produced minor amounts of volcanic ash.

The ash we are currently seeing at Whakaari / White Island is the result of a volcanic process called hydrothermal weathering: a time when the rock is softened by the percolation of acid gases and water. This occurs at the active vent, where high energy emissions of hot gases

are observed, which slowly erode the walls of the vent. This eroded rock material (small volumes of ash) is transported in the vapor and gas plume of the active crater. Thus, these ash grains are slowly reworked materials, not fragmented parts of magma from the depths or surrounding rocks.

 

The volcanic alert level is at 2 / Moderate to increased volcanic unrest; and the aviation code is Yellow.

 

Source: GNS

White Island- "ashing story" - photo 2021 / GNS

White Island- "ashing story" - photo 2021 / GNS

A new seismic swarm is affecting the Reykjanes Peninsula northeast of the Fagradalsfjall site, where no activity is noted.

A 3.7 magnitude earthquake rocked the region at seven o'clock last night. The source is 1.2 kilometers southwest of Keilir, but earthquakes of similar magnitude in recent days have their source there. There is no sign of agitation.

A total of seven earthquakes of magnitude 3.0 and above have been detected since the eruption began southwest of Keilir on September 27. In the past 24 hours, around sixteen hundred earthquakes have been detected, according to Bjarki Kaldalón Friis, nature conservation specialist at the Icelandic Meteorological Bureau, but nearly a hundred since midnight.

At around ten past ten in the evening, a magnitude 3.2 earthquake rocked southwest of Keilir. Before two hours today, a magnitude 3.5 earthquake was measured and just before the last two nights, a magnitude 3.7 earthquake was measured.

Reykjanes Peninsula - Location of sensitive areas: Fagradalsfjall and Keilir

Reykjanes Peninsula - Location of sensitive areas: Fagradalsfjall and Keilir

Reykjanes Peninsula - Seismicity at 01.10.2021 / 05h30 - IMO
Reykjanes Peninsula - Seismicity at 01.10.2021 / 05h30 - IMO
Reykjanes Peninsula - Seismicity at 01.10.2021 / 05h30 - IMO

Reykjanes Peninsula - Seismicity at 01.10.2021 / 05h30 - IMO

Kristín Jónsdóttir, director of geology at the Icelandic Meteorological Bureau, says she thinks the most likely explanation for the earthquakes is that the magma is looking for new paths.

Steam rises from the ground at Höskuldarvellir, a geothermal area on the north side of Keilir. Þorvaldur Þórðarson, professor of volcanology and geology, said in conversation with Fréttablaðið this evening that the steam could indicate that the magma is shallow enough to heat groundwater.

 Civil Defense today issued a press release recommending that the public not enter the Kelir area.

 

Sources: IMO, RUV

Keilir zone - location of earthquakes and forecast map of a possible extension of lava flows in the event of an eruption at Keilir - Doc. IMO / RUV 01.10.2021 - one click to enlarge

Keilir zone - location of earthquakes and forecast map of a possible extension of lava flows in the event of an eruption at Keilir - Doc. IMO / RUV 01.10.2021 - one click to enlarge

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