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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
Sabancaya - activity from 16 to 22.05.2022 - Doc. I.G.Peru

Sabancaya - activity from 16 to 22.05.2022 - Doc. I.G.Peru

According to the I.G.P., the eruptive activity of Sabancaya remained at moderate levels in the week of May 16 to 22, 2022, with an average of 21 explosions per day, accompanied by plumes of gas and ash reaching 2,300 M .above the top.

The detection of 356 earthquakes of volcanic origin associated with the circulation of magmatic fluids was detected, as well as VT earthquakes, linked to the fracturing of rocks.

The observatory does not report any significant deformation anomalies.

Four thermal anomalies, max. 25 MW, are associated with the presence of a lava dome in the crater. The Geological, Mining and Metallurgical Institute (Ingemmet), through its Volcanological Observatory (OVI), detected the formation of a new lava dome in the active crater of the Sabancaya volcano, Arequipa region, which, according to calculations from optical satellite images, on May 17, it reached an area of ​​more than 25,000 m², which is equivalent to almost four football fields. This new lava dome would be the fifth to form in the active crater of the Sabancaya volcano, named "Pichqa" because it means five in Quechua.

 

Faced with this situation, Ingemmet distinguishes between two possible scenarios: increasing the size of the dome or its total or partial destruction; the latter being the most likely and least dangerous scenario for the region. As for the eruption, a slight increase is expected in the coming months with the likelihood of more energetic explosions, higher eruptive columns, as well as longer range dispersal and ashfall, as seen. is produced in the four previous domes detected by the researchers of the institution.

The volcanic alert level remains at Naranja, with a non-accessible zone of 12 km radius.

 

Sources: Instituto Geofisico del Peru & Ingemmet / OVI

Villarica - Sernageomin flyover archive image -21.04.2015

Villarica - Sernageomin flyover archive image -21.04.2015

The Sernageomin highlighted a process of superficialization of the Villarica lava lake, which in turn generated an increase in long-term seismicity, the recording of acoustic signals, incandescence and an increase in recorded thermal alerts.

As observed in previous phases, the dynamics of the lava lake in its process of restitution to shallow levels can lead to punctual increases in activity such as those observed on April 26 and May 22, which could generate explosions minor with ejection of pyroclasts in the crater area and its area of ​​influence. Consequently, the zoning of the hazard is modified, considering an area likely to be affected by volcanic products within a radius of 300 m from the edge of the active crater.

The technical alert remains at the Green level.

 

Source: REAV Sernageomin

Ruapehu - photo GNS/Brad Scott

Ruapehu - photo GNS/Brad Scott

Gas emissions are still high at Mount Ruapehu. The temperature of the crater lake Te Wai ā-moe has dropped over the past week. The temperature of the crater lake has dropped from a peak of 41°C on May 8, 2022 to 30°C today. Heavy rains over the past week have caused the lake level to rise temporarily and the temperature of the lake to drop. The lake level has now returned to normal pre-rainfall levels, while the lake continues to cool, indicating a general decrease in the amount of heat entering the lake.

 

The last gas measurement flight, on May 13, 2022, confirmed elevated sulfur dioxide  and carbon dioxide  production of 179 and 1658 tonnes per day of gas, respectively. New instruments installed to automatically measure SO2 gas emissions from the volcano confirm that these remain high for Mount Ruapehu. Continued SO2 emission indicates gas being released from relatively shallow magma and suggests the volcano is still at an increased level of unrest.

 

Volcanic tremor levels have generally declined but remain variable. Volcanic unrest continues at Mount Ruapehu and the potential for eruptive activity remains. The Volcanic Alert Level remains at 2.

These observations are consistent with a slowing or blocking of magma intrusion into the volcano.
Over the next four weeks, the most likely outcome of this episode of unrest is minor eruptive activity confined to the lake basin, or no eruption. Minor eruptions can generate lahars (dangerous volcanic mudslides) in the Whangaehu River.

The current alert level is at 2 and the aviation code remains at Yellow.

 

Source: GeoNet

Hunga-Tonga Hunga-Ha'apai - bathymetry of the caldera - Doc. Prof. Shane Cronin / Univ. Auckland & Tonga Geological Services – via BBC 23.05.2022 - one click to enlarge

Hunga-Tonga Hunga-Ha'apai - bathymetry of the caldera - Doc. Prof. Shane Cronin / Univ. Auckland & Tonga Geological Services – via BBC 23.05.2022 - one click to enlarge

New Zealand's National Institute for Water and Atmospheric Research (NIWA) released its bathymetric (depth) map for the area immediately around the Hunga-Tonga Hunga-Ha'apai volcano on Monday.

The volcano's caldera is now 4 km (2.5 miles) wide and drops 850 m below sea level.
Before the catastrophic eruption, the base was at a depth of about 150 m. After the eruption, it is overcome by more than 800m. of water.

This accounts for the magnitude of the volume of material ejected by the volcano - at least 6.5 cubic km of ash and rock.

A comparison with pre-eruption maps of the caldera, made in 2016 and 2015, shows the major changes.
In addition to general deepening, large chunks were lost from the inner cliff faces, particularly at the southern end of the crater.

 

Source: Prof. Shane Cronin / Univ. Auckland & Tonga Geological Services – Doc. BBC

HTHH - Seabed Topographic Change - NIWA via BBC - one click to enlarge

HTHH - Seabed Topographic Change - NIWA via BBC - one click to enlarge

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