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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
 Asama - incandescence shortly preceded the emission of a black plume / 07.08.2019 - photo MAEJIMA Yoshinori / Twitte

Asama - incandescence shortly preceded the emission of a black plume / 07.08.2019 - photo MAEJIMA Yoshinori / Twitte

Asama - status on 07.08.2019, respectively at 22:01 and 22:09 - Doc. JMA - one click to enlargeAsama - status on 07.08.2019, respectively at 22:01 and 22:09 - Doc. JMA - one click to enlarge

Asama - status on 07.08.2019, respectively at 22:01 and 22:09 - Doc. JMA - one click to enlarge

A small eruption occurred at Mount Asama, on the Japanese island of Honshu, on July 22 at 22:08 local time, marked by a strong incandescence, followed by the emission of a black volcanic plume that exceeded 1,800 m at above the edge of the crater.

Volcanic ash is reported in small quantities north of the crater on Naganohara, Tsumagoi, Karuizawa, and Miyota.

In addition, to the northeast of the crater over a distance of about 2 km, there is a risk that ash will be blown away.

The JMA has passed the alert level of 1 to 3, out of 5 / do not approach the volcano, this August 7 at 22:30 JST.

Asama - Temple on the Onioshidashi Flood North (1783) - photo Richard Fiske, 1961 (Smithsonian Institution).

Asama - Temple on the Onioshidashi Flood North (1783) - photo Richard Fiske, 1961 (Smithsonian Institution).

This small eruption follows the activity of June 16, 2015.

Asama, Honshu's busiest volcano, overlooks the resort town of Karuizawa, 140 km northwest of Tokyo. The volcano is located at the junction of volcanic arcs of Izu-Mariana and northeastern Japan.

Asama is a stratovolcano. Three overlapping bodies make up this volcano. It is a young stratovolcano with two craters lying on a shield volcano. The shield volcano rests on an older stratovolcano.

Kurohu-yama is the name of the western crater rim of the older stratovolcano. It rises to a height of 2405 m. Erosion has widened this crater to about 2 km. The water rests in the crater and is drained to the southwest. The eastern part of this stratovolcano was destroyed and buried under a shield volcano. A younger stratovolcano also rests on this shield.

This younger stratovolcano has two craters. The southwest edge of the outer crater is Maekake-yama. It rises to 8177 feet (2493 m) high. The outer crater is approximately 1200 m (3900 ft) from east to west and 900 m (3000 ft) from north to south. This crater is located about 2 km east of Kurohu-yama.

Kama-yama is a cone in the center of the outer crater. It is 8364 feet (2550 m) high. This cone rises 170 m above the bottom of the crater. Its crater is about 350 m wide and is very active.

 

Sources: JMA / Japan Meteorological Agency, NHK, Kyodo news

Asama - cone Maekakeyama, crat. Kamayama, Kuforuyama summit on the right - photo 2009 Tokyo Univ.

Asama - cone Maekakeyama, crat. Kamayama, Kuforuyama summit on the right - photo 2009 Tokyo Univ.

The eruptive-effusive activity of Karangetang continues, characterized by hot spots at both craters and a lava flow to the west, respectively 1,500 meters to Kali Pangi and Kali Nanitu, and 1,750 meters to Kali Sense.

The PVMBG reports for 7 August 68 earthquakes of eruption, 10 earthquakes of blast, a hybrid earthquake and continuous tremor of dominant amplitude to 0.25 mm.

The level of activity remains at 3 / siaga, with a forbidden zone of 2.5km from the summit, lengthened to 4 km to the north.

 

Sources: PVMBG & Sentinel-2

Karangetang - lava flows on the western slopes 07.08.2019 - photo Badan Geologi

Karangetang - lava flows on the western slopes 07.08.2019 - photo Badan Geologi

Karangetang - hot spots craters and lava flows of the south crater, 07.08.2019 - image Sentinel-2 L1C image bands 12,11,4

Karangetang - hot spots craters and lava flows of the south crater, 07.08.2019 - image Sentinel-2 L1C image bands 12,11,4

In Ecuador, the activity of Sangay is illustrated by the video below, made during a control overview on August 6, 2019 by the IGEPN.

The height of the emission exceeds 1700 meters above the crater level and towards the west. Based on these considerations, a slight presence of volcanic particles in the environment could be recorded, mainly in the province of Guayas. The Institute of Geophysics of the National Polytechnic School monitors the activity of the volcano and informs changes that may be recorded.

 

Source: IGEPN

Sangay - thermal anomalies on 08.08.2019, stronger on August 6 - Doc.Mirova

Sangay - thermal anomalies on 08.08.2019, stronger on August 6 - Doc.Mirova

Flyghtover Sangay volcano - 06.08.2019 - IG EPN

The study and the treatment of the images obtained by various satellite systems such as SENTINEL showed the presence of a hot body / lava plug, marked by a crack of depressurization, in the crater of the Ubinas volcano, which would indicate the proximity of the magma and the possibility of explosive eruption.

 These images have been acquired since the first days of August and corroborate the conclusions of the seismic analysis carried out.

Ubinas crater and cracked lava plug - photo Ingemmet

Ubinas crater and cracked lava plug - photo Ingemmet

The number of seismic signals that would be related to the rise of magma inside the Ubinas volcano has increased in recent hours, according to the National Center for Vulcanology (CENVUL) in its latest update after analyzing the seismic data obtained by the stations installed near the volcano.

From 15h33 August 5th, harmonic tremor-type signals were observed, previously unseen seismic events recorded only on volcanoes erupting when the magma reached areas close to crater surface. " The harmonic tremors are earthquakes that would be generated by the resonance of the cracks formed after the pressure of the rise of magmatic fluids.This situation would condition the direct and continuous escape of magmatic gases (SO2, CO2, among others) through the crater in the atmosphere, "said engineer Jose Del Carpio, researcher at IGP.

In this context, the possibility of new volcanic explosions in the next hours or days is strengthened, because the harmonic tremors are short-term indicators of new explosive episodes. It is therefore recommended to the population to follow the recommendations of the civil defense authorities, who have been informed in real time of the state of Ubinas volcano.

Ubinas - harmonic tremor - Doc. PGI 05.08.2019

Ubinas - harmonic tremor - Doc. PGI 05.08.2019

Ubinas - seismicity associated with rise of magma - Doc. PGI 06.08.2019

Ubinas - seismicity associated with rise of magma - Doc. PGI 06.08.2019

The National Center for Vulcanology (CENVUL), a service of the Geophysical Institute of Peru (IGP) dedicated to the monitoring and warning of volcanic activity in the country, will continue to publish updates detailing the evolution dynamic behavior of Ubinas as part of its current eruptive process.

 

Sources: IG Peru - Ingemmet - CENVUL

Ubinas -situation on 07.08.2019 at 20h - Doc. IGP / Senamhi

Ubinas -situation on 07.08.2019 at 20h - Doc. IGP / Senamhi

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