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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

A strong explosion occurred at the Nevados de Chillan complex on December 28th at 22:11 local / December 29 at 01:11 UTC; it was accompanied by an LP earthquake associated with fluid dynamics, with a hypocenter at one km depth.

Incandescence due to the emission of gases and pyroclastic materials at high temperature was observed, as well as external projections on the upper flank.

This episode is to link with the partial destruction of the dome, as part of the construction-destruction cycle started in December 2017.

On a Planetlabs video, it's possible to see a new and small crater on the eastern edge of Nicanor crater.

The technical alert remains at the Naranjo level.

Sources: Sernageomin & Felipe Aguilera

Nevados of Chillan - 28.12.2018 / 22:12 and 22:18 - Sernageomin photos

Nevados of Chillan - 28.12.2018 / 22:12 and 22:18 - Sernageomin photos

The KVERT momentarily changed the Sheveluch's aviation code from orange to red, following a continuation of the activity.

This December 30 at 00:45 UTC, an explosion of ashes was accompanied by two plumes. Satellite data show a first plume at 10-11 km asl drifting 35 km to the northeast, and a second plume at 6-7 km asl, drifting 244 km to the west-southwest of the volcano.

Sheveluch - ash explosion this 30.12.2018 / 0:45 UTC - photo Y.Demyanchuk

Sheveluch - ash explosion this 30.12.2018 / 0:45 UTC - photo Y.Demyanchuk

Sheveluch - Volcanic ash advisory of 30.12.2018 / 01h11 Z - Doc. VAAC Tokyo

Sheveluch - Volcanic ash advisory of 30.12.2018 / 01h11 Z - Doc. VAAC Tokyo

The aviation code returning orange at 6:14. ; the eruptive activity producing an ash plume at 5-6 km asl drifting 245 km to the southwest then to the west.

Steam and gas degassing continues.

Source: KVERT

Agung - 30.12.2018 -  eruption on vidéo at 4:12 am WITA and ashfall - montage Magma Indonesia

Agung - 30.12.2018 -  eruption on vidéo at 4:12 am WITA and ashfall - montage Magma Indonesia

An eruption marked the Gunung Agung, on the island of Bali, this December 30 at 04:09 WITA; she said 3 minutes 8 sec., with an amplitude of 22 mm on the seismogram.

The eruption is due to an "overpressure" due to the accumulation of volcanic gases. At the time of the eruption, an incandescence was observed at the top, but the height of the ash column was not observed due to the fog. According to satellite information, the volcanic ash is moving towards the southeast, reaching 5,500 m altitude. An orange aviation code has been established by VAAC Darwin.

Light ash rains were reported in the Karangasem regency, in the southeastern sector of Mount Agung, as in the city of Amlapura and in several villages including Seraya Barat, Seraya Tengah and Tenggalinggah.

Several volcanic earthquakes were recorded, including the earthquake on the northern slope of Mount Agung on December 28, 2018 of magnitude M2.7 at 2:49 WITA and M2.4 at 15:31 WITA. These earthquakes indicated the movement of magma towards the surface.

Based on the overall data analysis, the potential for a larger eruption is still relatively low. Eruptions that may occur at this time may take the form of ejection of incandescent rocks / lava, ash rains, or gusts of volcanic gas.

Until 30 December 2018 at noon WITA, it can be concluded that the activity status of Mount Agung is still at level III (pending) with a recommendation to estimate the danger zone in all areas within a radius. 4 km from the peak. The estimated danger zone is dynamic and continues to be evaluated.

The last eruption of Agung dates from July 27, 2018.

Sources: Magma Indonesia & VAAC Darwin

Etna - the NSEC & the eruptive crack - photos Joseph Nasi / Butterfly helicopters 28.12.2018 / 9h47-48 GMT
Etna - the NSEC & the eruptive crack - photos Joseph Nasi / Butterfly helicopters 28.12.2018 / 9h47-48 GMT

Etna - the NSEC & the eruptive crack - photos Joseph Nasi / Butterfly helicopters 28.12.2018 / 9h47-48 GMT

A mapping of the eruptive fissure, slag cones aligned above it and the lava field of Etna 24-27.12.2018 eruption was carried out by an overflight by the INGV and the coastguards of Catania.

The eruptive fissure consists of three segments: the northernmost is located just north of the new southeastern crater, at about 3,100 meters above sea level. This segment produced only a modest Strombolian activity of a few tens of minutes. The intermediate segment is located in the NNO-SSE direction and is approximately 750 meters long; it lies between the lower east flank of the new south-east crater, at a little over 3,100 meters above sea level, and the edge of the Valle del Bove, at about 2,875 meters. The lower segment of the crack enters Valle del Bove, crosses its west wall and stops at about 2,400 meters. It is about 1000 meters long, still in the NNO-SSE direction, but slightly eastward in relation to the segment described above.

The area covered by the erupting products does not exceed 1 square kilometer. According to a very preliminary estimate, the average thickness of these products varies between 3 and 6 meters. As a result, the total volume erupted is between 3 and 6 million cubic meters. On the evening of December 27, the most advanced lava front was very slow.

 

Source: Preliminary map of the Etna eruption from 24 to 27 December 2018 by Marco Neri

Etna - Preliminary map of the products of the eruption of 24 to 27 December 2018 - INGV Technolab via M.Neri

Etna - Preliminary map of the products of the eruption of 24 to 27 December 2018 - INGV Technolab via M.Neri

Etna - Result of interferometric processing in phase of SAR data - 2018.12.28 / 2018.12.22 - Doc. INGV

Etna - Result of interferometric processing in phase of SAR data - 2018.12.28 / 2018.12.22 - Doc. INGV

SAR (Synthetic Aperture Radar) images from the following two passages of the ESA Sentinel 1 satellite (European Space Agency), on 22 and 28.12.2018 were analyzed.

The geometry of the view of the sensor is decreasing ( East-South-East point of view of Etna, with an inclination of about 40 °).

The result of the interferometric treatment in the phase of SAR data included here (1 fringe = 28 mm of displacement along the line of sight) highlights a complex deformation field affecting the whole volcano.

The intrusion of 24 December in the upper Bove Valley, which caused a maximum deformation of about 16 cm to the west and 20 cm to the east;

The Fiandaca-Pennisi, Pernicanca and Ragalna faults were activated during the seismic swarm still recorded by the Etna networks.

Source and Details: Interferometric analysis of Sentinel-1 data Etna 22-28 / 12/18: preliminary report - link

Etna - towards a return to calm? - photo Gio Giusa 27.12.2018

Etna - towards a return to calm? - photo Gio Giusa 27.12.2018

 Etna - tremor at 29.12.2018 / 6h10 - INGV Catania

Etna - tremor at 29.12.2018 / 6h10 - INGV Catania

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