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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
The composite cone of Mount Edgecumbe - Photo AVO 2004 / D.Marriott

The composite cone of Mount Edgecumbe - Photo AVO 2004 / D.Marriott

A swarm of earthquakes was detected near Mount Edgecumbe Volcano, beginning around 2 a.m. AKDT on Monday, April 11, 2022. There were hundreds of small earthquakes in the swarm, although the vast majority are too small to locate.

The National Earthquake Information Center reported that one of the largest earthquakes in the swarm occurred at 11:04 a.m. AKDT on April 11, with a magnitude of 2.8 at 10 km. depth. The Alaska Earthquake Center reported that another earthquake occurred at 3:44 p.m. AKDT on April 11, with a magnitude of 2.1 and a depth of 4 km. Since this morning, the swarm continues, although the rate of earthquakes has decreased over the past 24 hours.
The cause of this earthquake swarm is currently unknown. This swarm may be associated with volcanic processes, regional tectonic activity, or a combination of sources. AVO does not have local seismic instruments in the area, and the nearest station is at Sitka, 24 km (15 miles) east of the volcano.

The current volcano alert level and aviation color code remain "Unassigned".

To be continued ...

Edgecumbe volcano - photo AVO / D.Marriott 2004

Edgecumbe volcano - photo AVO / D.Marriott 2004

The Edgecumbe volcanic field in southern Kruzof Island lies on the North American Plate 10-15 km inside the Queen Charlotte-Fairweather Transform Fault. The Edgecumbe volcanic field is dominated by the symmetrical stratovolcano of Mount Edgecumbe and the domes and crater of the adjacent crater. Ridge. Mount Edgecumbe was named by Captain James Cook in 1778. The basal shield comprises approximately 35 km3 and consists of basalt, basaltic andesite and lava flows and andesite breccias. The Mount Edgecumbe composite cone is composed primarily of andesite and has a volume of approximately 3.5 km3. Crater Ridge's low-silica rhyolite domes also contain about 3.5 km3 of magma.

 

Source: AVO

Puracé - photo Federman Escobar Chávez, 2005 / GVP-11786

Puracé - photo Federman Escobar Chávez, 2005 / GVP-11786

After the opening of two fractures at Puracé on March 29, 2022, and observations of gas and ash, its alert level was raised to 2 / yellow on March 30. (see http://www.earth-of-fire.com/2022/03/news-from-purace-taal-nishinoshima-and-ruapehu.html)

Seismicity continued to be elevated until April 4. The earthquakes were of low magnitude, and located about 800 m SE of Puracé and under Curiquinga, at depths of 2 km on average. The number of events signifying increased movement of fluids. The geodetic network GNSS (Global Navigation Satellite System) and DInSAR (Differential Interferometry by Synthetic Aperture Radar) showed inflation at the millimeter scale. Emissions of sulfur dioxide and carbon dioxide increased, based on satellite and ground sampling data, and a fumarole on the N flank of Purace intensified and produced a strong smell of sulfur.

Significant unrest continued from 5 to 11 April. The seismic network recorded a total of 2,077 earthquakes, consisting of 248 VT events, 1,759 LP events, 37 low-energy TR events and 31 hybrid events. Millimetre-scale inflation persisted, and sulfur dioxide emissions averaged 1,800 tons per day.

 

Sources: SGC, via Global Volcanism Program

Stromboli - 12.04.2022 - image Sentinel-2 bands 12,11,8A (via Mounts project) - and 3D view facing the sciara del Fuoco (via Copernicus) - one click to enlarge
Stromboli - 12.04.2022 - image Sentinel-2 bands 12,11,8A (via Mounts project) - and 3D view facing the sciara del Fuoco (via Copernicus) - one click to enlarge

Stromboli - 12.04.2022 - image Sentinel-2 bands 12,11,8A (via Mounts project) - and 3D view facing the sciara del Fuoco (via Copernicus) - one click to enlarge

During the week of 04.04.2022 to 10.04.2022, normal Strombolian-type explosive activity was observed, mainly produced by five eruptive vents located in the North crater area and two eruptive vents located in the Center-South crater area. All the mouths are placed inside the depression that occupies the crater terrace of Stromboli.


The total hourly frequency of explosions fluctuated between medium values ​​(15 events/h) and medium-high values ​​(19 events/h). The intensity of the explosions was mainly medium and low in both the North Crater area and the Center-South Crater area.
The seismological parameters monitored do not show any significant variations.
During the past week, no seismic signal associated with landslides has been recorded.
The island's soil deformation monitoring networks did not show any significant variation.
The flux of SO2 at an average level
CO2 fluxes in the crater area remain at medium to high values.
High values ​​of the isotopic ratio of He dissolved in the heat sinks.

The thermal activity observed by satellite was at a low level.

 

Source: INGV OE

Average hourly frequency per day and per week per crater area and in total of Stromboli explosive activity (thin and bold line, respectively). Data viewing conditions are shown at the top of the graph and activity levels at the right; the green bar indicates the typical average level of explosive activity at Stromboli - Doc. INGV OE

Average hourly frequency per day and per week per crater area and in total of Stromboli explosive activity (thin and bold line, respectively). Data viewing conditions are shown at the top of the graph and activity levels at the right; the green bar indicates the typical average level of explosive activity at Stromboli - Doc. INGV OE

In light of monitoring data from La Fossa de Vulcano, temperature data recorded on the crater rim show stable values ​​at high levels.
The flow of CO2 in the crater area attests to high values ​​of 12281 g m-2 d-1. 
The CO2 flux at the base of the La Fossa cone and in the Vulcano Porto area (C. Sicilia and P4max sites) continues to show a slight downward trend, but remains at values
medium-high; in the Faraglione site there are values ​​close to the background.
The SO2 flux in the crater area is at a medium-high level and moderately increasing
Geochemistry of fumarolic gases: The last sampling confirmed the downward trend of magmatic species in fumarolic gases.
Geochemistry of thermal aquifers: The temperature measured in the Camping Sicilia well is at high and stable values. The electrical conductivity shows low values.
The level values ​​measured in the Bambara well show a small fluctuation. Conductivity values ​​remain constant at medium-high levels.
Local seismicity is characterized by a low event occurrence rate.
Moderate fracturing seismicity associated with earthquakes with Ml >= 1.0.
The networks of permanent and clinometric GNSS stations did not register any significant changes.

 

Source: INGV OE

Vulcano - 13.04.2022 / 14:39 - webcam INGV OE Vlv0293

Vulcano - 13.04.2022 / 14:39 - webcam INGV OE Vlv0293

Vulcano - photo INGV OE  04.04.2022

Vulcano - photo INGV OE 04.04.2022

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