Activity of Sangay, Anak Krakatau and Etna.

Sangay - lava and plume flow from 04.05.2020 - IGEPN webcam

In Ecuador, the surface and internal activity of Sangay remains unchanged, and qualified as "High".

On May 5, IGEPN noted 7 explosions, and ash emissions could be observed towards the southwest.

VAAC alerts were recorded with heights of 870 meters above the level of the crater and in a southwest direction.

On the southeast flank, the lava flows remain active, and thermal anomalies are reported by Mirova of VRP 90 MW on May 4 at 6:55 p.m., and of VRP 13 MW on May 5 at 4:20 a.m.

A lahar signal was recorded in the volcanic station on the afternoon of May 4, with a duration of 3 hours.

Sources IGEPN and VAAC Washington.

Sangay - thermal anomalies on 06.05.2020 / 03h25 - Doc. Mirova_MODIS_Latest10NTI

Seismic activity remains high on May 5, 2020 at Anak Krakatau, although slightly down from the previous day with:

- 26 blast earthquakes, with an amplitude of 3-22 mm and an earthquake duration of 6-82 seconds.

- 148 low frequency earthquakes, with an amplitude of 4 to 30 mm and the duration of the earthquake from 4 to 14 seconds.

- 8 hybrid earthquakes, with an amplitude of 6 to 9 mm, the S-P is not observed and the duration of the earthquake is 5 to 10 seconds.

- 4 episodes of continuous tremor with an amplitude of 0.5-8 mm, dominating 2 mm.

The activity level remains at 2 / waspada

Sources: PVMBG & Magma Indonesia

Anak Krakatau - seismicity at 05.05.2020 - Doc. Magma Indonesia - one click to enlarge

In the week of April 27 to May 3, Etna presented a strombolian activity to Voragine (VOR) and to the new southeast crater (NSEC).

Etna - 03.05.2020 / 10:20 am - photo Casa di paglia Felcerossa.

Map of the summit crater area (DEM 2014, Aerogeophysics Lab - Section Rome 2, mod.) And detail of the VOR-BN area of Etna. Indented black lines = edge of the upper craters: BN = Bocca Nuova, with the depressions of the northwest (BN-1) and the southeast (BN-2); VOR = sinkhole; NEC = Northeast Crater; SEC = Southeast Crater; NSEC = New southeast crater. The indented blue line indicates a depression inside BN. Yellow dots = degassing vents. Red dots = mouths with eruptive activity. - Doc. INGV OE

At La Voragine, an inspection on April 30 revealed that the effusive activity of the mouth of the principal cone had stopped, in progress since September 12, 2019, and the lava field is being cooled.

Strombolian activity continues on the other hand at the level of the intracrateric cones of the VOR, with gray-black ash emissions several hundred meters high, during the main cone explosions. During the night of May 3-4, the strombolian explosions from the VOR crater appeared particularly energetic, and the coarse material produced fell outside the edges of the crater, settling on the southern flank of the Bocca Nuova crater. .

It was also observed that the depression that formed inside the BN of the crater has increased compared to what was observed during the inspection of April 18, 2020.

Etna - a) Overview of the BN and VOR craters taken during the May 1 inspection from the edge south of BN. The arrow indicates the depression which widens at the bottom of the BN crater (photo M.Coltelli). b) thermal image of the area framed in yellow in a), taken during the inspection on April 30. Active flows are no longer present and the entire lava field cools down (images by L. Lodato). - Doc INGV OE

Etna - Thermal images of strombolian activity at the VOR crater from the a) main cone formed on 12/09/2019 and b) from the cone formed on 03/09/2020, photos during the inspection on 1 May (taken by F. Ciancitto). - Images of cameras visible from La Montagnola showing c) strong Strombolian activity in the VOR crater and d) the coarse products of the explosions which fall on the southern flank of the BN crater. - Doc. INGV OE

Etna VOR - activity of 03.05.2020 - photo Gianni Pennisi

During the week, a pulsatile degassing of the new Southeast crater continued. The presence of flashes at night showed that strombolian activity continued at the level of the "saddle cone", without expelling incandescent materials. Sometimes this activity was accompanied by the emission of reddish ash, quickly dispersed in the atmosphere.

Source / INGV OE - weekly bulletin 27.04 / 03.05.2020