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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
Sinabung - 05.09.2020 / 05h47 - photo Nachelle Homestay ... the place to be !

Sinabung - 05.09.2020 / 05h47 - photo Nachelle Homestay ... the place to be !

Sinabung - 09/05/2020 / 6:11 WIB - PVMBG webcam - Magma Indonesia

Sinabung - 09/05/2020 / 6:11 WIB - PVMBG webcam - Magma Indonesia

The Sinabung experienced an eruptive episode on Saturday September 5, 2020 at 05:13 WIB with an ash plume observed ± 800 m above the summit (± 3260 m above sea level). The ash column was gray with thick intensity, to the north and northeast. This eruption was recorded on a seismograph with a maximum amplitude of 2 mm and a duration of 1164 seconds.

Communities and visitors / tourists are recommended not to carry out activities in villages that have been displaced, as well as within a radius of 3 km from the summit of G. Sinabung, as well as a sector radius of 5 km for the south-eastern sector and 4 km for the east-north sector. In the event of ash rain, people are advised to wear masks when leaving the house to reduce the health effects of volcanic ash. Secure drinking water facilities and clean roofs of houses from dense volcanic ash so that it does not collapse.People who live near rivers draining the Sinabung should remain alert to the dangers of lahars

 

Sources: PVMBG, Magma Indonesia and VAAC Darwin

Dukono - 04.09.2020 / 15:47 WIB - webcam PVMBG Magma Indonesia

Dukono - 04.09.2020 / 15:47 WIB - webcam PVMBG Magma Indonesia

In the Moluccas, the activity of Dukono remains important.

The VAAC Darwin issued an ash scatter advisory on September 5 at an altitude of flight 70. The signal was seen on satellite images moving northwest, then was obscured by clouds.

 

Sources: PVMBG and VAAC Darwin

  Kilauea - the summit as seen from Kīlauea Overlook. - photo 02.09.2020 / USGS by K. Miluken

Kilauea - the summit as seen from Kīlauea Overlook. - photo 02.09.2020 / USGS by K. Miluken

The Kīlauea Overlook has reopened to the public for the first time since the eruption of the Lower East Rift Zone and the summit collapse in 2018.

Map of Kilauea Volcano with schematic magma plumbing system. a, Magma rises beneath the summit of Kilauea, passes through the summit reservoir system (here simplified as a single reservoir), and migrates down the ERZ before eruption. Magma storage occurs in the summit and deep ERZ. b, Schematic section along dotted line in a, indicating gas emissions and ground deformation observations. - Doc . K.Anderson & M.Poland

Map of Kilauea Volcano with schematic magma plumbing system. a, Magma rises beneath the summit of Kilauea, passes through the summit reservoir system (here simplified as a single reservoir), and migrates down the ERZ before eruption. Magma storage occurs in the summit and deep ERZ. b, Schematic section along dotted line in a, indicating gas emissions and ground deformation observations. - Doc . K.Anderson & M.Poland

What about the underlying summit magmatic system and how does it behave?

 

Prior to 2018, geophysical data showed a complex system of magma storage chambers beneath the summit of Kīlauea. One of the most important was a shallow chamber (about a mile or 1 mile deep) below the Kīlauea caldera, called the Halema'uma'u reservoir. This reservoir was connected to the surface via a conduit that formed the Overlook Crater and supplied lava to the summit lava lake.

The first clue to the post-collapse state of the shallow reservoir came in October 2018 when summit inclinometers detected a phenomenon called a deflation-inflation event (DI event).

While the DI events were clearly observable at the top of Kīlauea, inclinometers near Pu'u 'Ō'ō recorded similar movements with a slight delay.

That the pressure changes during the deflation and inflation of the summit reservoir could be transmitted so directly to the Pu'u '''ō was an indication of the close connection between the East Rift Zone and the magmatic system of the Mountain peak.

Additionally, inclinometers in the East Rift Zone showed a faint trace of a DI event just after the October event. This indicates that the close connection between the shallow Halema'uma'u reservoir and the East Rift Zone still exists.

 

The analyzes made it possible to calculate the total quantity of magma in the Halema'uma'u reservoir more precisely than ever.

Given the natural uncertainty of the data, they found that the most likely reservoir volume was just under 4 cubic km (about 1 cubic mile). Considering the collapse volume of 0.8 cubic km (0.2 cubic mile), this means that only about 20% of the reservoir was emptied during the 2018 eruption and 80% of the reservoir's magma is still under the top.

So while the surface of the Kīlauea Caldera has undergone a major remodeling, underneath, the magma plumbing system still functions the same as before.

This is reassuring, because it means that the results of studies of the Kīlauea magmatic system over the past decades can still be applied to current monitoring efforts. The 2018 eruption has already provided incredible insights into Kīlauea's structure and behavior and can still teach us more.

 

Source: USGS Volcano Watch, by Ingrid Johanson, research geophysicist at the Hawaiian Volcanoes Observatory.

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