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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
Aerial view of active vents at Whakaari/White Island as of 03.23.2022, showing areas of collapse (red dotted line). The bright colors are hydrothermal minerals precipitated to the ground. - GeoNet photo - one click to enlarge

Aerial view of active vents at Whakaari/White Island as of 03.23.2022, showing areas of collapse (red dotted line). The bright colors are hydrothermal minerals precipitated to the ground. - GeoNet photo - one click to enlarge

Recent observation and gas measurement flights to the Whakaari/White Island volcano confirm that dilute ash emission has currently ceased. A subsidence has occurred in the 2019 primary crater. The Volcanic Alert Level remains at Level 2.

During the gas measurement flight, a geyser was observed from a small gray colored pool on the south side of the 2019 primary crater. A little over an hour later, during a flight of observation, the pool had disappeared and a collapse pit was present. The observation flight also established that a larger collapse structure was present in the crater, but it is not known exactly when this occurred. The formation of collapse craters at Whakaari/White Island was common in the past and was thought to be caused either by the withdrawal of liquid below the crater or by the removal of fine-grained ash during recent emissions of ashes. Although this collapse activity poses no immediate danger, it shows that the shallow crater environment remains dynamic and changes in response to pressure variations beneath the active craters. This is a sign of continuing troubles.
Gas emissions have decreased since the last measurements and vent temperatures are also below about 290 C. The lake water level has dropped slightly in recent weeks. The volcanic tremor remains weak.

The current activity level corresponds to moderate to high levels of agitation. Thus, the Volcanic Alert Level remains at 2 and the Aviation Color Code remains at Yellow.

 

Source: GeoNet 23.03.2022

Etna - winter conditions on the 1st day of spring - photo Boris Behncke 22.03.2022

Etna - winter conditions on the 1st day of spring - photo Boris Behncke 22.03.2022

Overall, the state of activity of the summit craters of Etna showed, during the week of March 14 to 20, 2022, no variation compared to that observed the previous week. In particular, the degassing activity of the summit craters was mainly carried by the crater of the well located in the northwest sector of Bocca Nuova, characterized by an intense sometimes impulsive degassing.
The Voragine craters and the NE craters, on the other hand, showed a predominant degassing linked to fumaroles present along the edges of the crater.
Seismic fracturing activity is characterized by an event of M = 3.3. Tremor amplitude: medium to medium level.
Infrasound activity is moderate.
Ground deformation monitoring networks have not
experienced significant changes over the past week.

Stromboli - activity in the northern area of ​​the craters - INGV OE webcam at 20.03.2022 / 2:15 p.m.

Stromboli - activity in the northern area of ​​the craters - INGV OE webcam at 20.03.2022 / 2:15 p.m.

Normal activity was observed in Stromboli for the period from March 14 to 20, explosive of the Strombolian type with projection activity in the North zone.

The total hourly frequency of explosions fluctuated between medium (11 events / h) and medium-high (18 events / h) values. The intensity of the explosions was mainly medium to low in the North Crater area and low in the Center-South Crater area.

Vulcano - photo archives © Bernard Duyck - one click to enlarge

Vulcano - photo archives © Bernard Duyck - one click to enlarge

The temperatures recorded on the edge of the crater of La Fossa in Vulcano show stable values.
The CO2 flux in the crater area remains at high values. The CO2 flux at the base of the La Fossa cone and in the Vulcano Porto area: CO2 fluxes recorded in the Rimessa, C. Sicilia and P4max sites, show a slight downward trend, but remain at average values -raised; in the Faraglione site, there are values ​​close to the base.
The SO2 flux in the crater area : SO2 flux at a medium-high level.

Geochemistry of fumarolic gases: No update is available.
Geochemistry of thermal aquifers: the physico-chemical parameters recorded in the Camping Sicilia well show modest drops in temperature and salinity, while one can be observed in the Bambara well with stabilization of the piezometric level and a slight decrease in salinity .


Local seismicity: low rate of occurrence of local events.
Regional seismicity: No earthquake with Ml >= 1.0 was located in the area of ​​the island of Vulcano.
The network of permanent GNSS stations has not registered any significant changes.

 

Source: the various INGV OE reports on activity between March 14 and 20, 2022 (posted on March 22, 2022)

São Jorge - seismic swarm on 03.22.2022 - Doc. SAPO - one click to enlarge

São Jorge - seismic swarm on 03.22.2022 - Doc. SAPO - one click to enlarge

Since Saturday afternoon, +1800 earthquakes have been recorded on the western half of São Jorge, in the Azorian archipelago, ... at least 94 have been felt by the population.

 

"The fact that the seismic crisis is located in the fissural volcanic system das Manadas leads to call it a seismovolcanic crisis, and all scenarios must be considered, including a larger magnitude earthquake or a possible eruption", reads -we. in the note published by the SAPO, recalling that the municipalities of Velas and Calheta activated their municipal civil protection emergency plans on Monday.

Azores - São Jorge: focus on the outstanding seismic swarm - GeologyHub video - http://YouTube.com/c/GeologyHub

The last passage of Sentinel on March 21, 2022 at 7:49 p.m. made it possible to establish an interferogram revealing a real deformation of the ground. This deformation cannot simply be explained by seismic activity and may have an origin of magmatic uplift. If you live in or near any of these places, be prepared to evacuate on short notice. (Civil protection)

 

Whether the origin of the earthquakes is tectonic (we are at a triple plate junction point), or volcanic (with a rich past and an uncertain future), its evolution will be interesting to follow.

 

The Azores microplate is at the triple junction point between the American, Indo-European and African plates

 

Source: SAPO – SRPCBA / Serviço Regional de Proteção Civil e Bombeiros dos Açores - GeologyHub

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