Etna update, 02.12.2022:
Since 27 November, lava has been erupting from the north-eastern base of the New Southeast Crater. This forms a short and narrow flow that is heading towards Valle del Leone. The tremor was temporarily increased and seismic activity is slightly enhanced.
Bad weather with fresh snow frequently hindered observations of the summit craters via webcams during the last 14 days. During the few cloud-free hours, Bocca Nuova continued to show the usual gas emissions, which were still strong and mostly intensified in pulses.
At Voragine and Northeast Crater, no significant gas releases were visible.
At the Southeast Crater complex, some gas was persistently emitted from the central area between the new and old Southeast Crater. In the northern summit area, fumaroles continuously released some gas.
After a stormy and cloudy day, the clouds slowly cleared on the evening of 27 November around 17:30 and suddenly a small thermal anomaly was visible on the Cagliato thermal cam. This was localised at the northeastern base of the New Southeast Crater. A little later, other webcams also showed several small glowing spots in this area, which is located at about 2800 m altitude. In the course of the evening, the glow intensified a bit more and a short lava flow was visible, slowly moving north/northeast towards the Valle del Leone. On the other hand, I was not able to see any glow in the summit area of the New Southeast Crater, but the cone was also often hidden in clouds.
During the night of 28 November, the lava emission continued, but the lava flow hardly progressed. On the morning of 28 November, around 06:30, only a little glow could be seen at the effusive vent. Later, clouds moved in and lingered until 29 November. However, no more activity was visible through some gaps in the clouds.
In the evening of 29 November, glow was again visible at the northeastern base of the New Southeast Crater from about 19:30. The Cagliato thermal camera also showed a small thermal anomaly a little later. Again, lava poured towards the Valle del Leone. In contrast to the eruptive event of 27 November, this time the tremor also increased significantly and reached almost high levels. The effusive vent was located slightly more slope upwards on the NE flank of the New Southeast Crater than during the 27 November eruption.
During the night of 30 November, lava emission continued, but the lava flow gained length very slowly. After the clouds cleared in the evening of 30 November, the northeastern base of the New Southeast Crater continued to show glowing spots. Effusive activity continued on 01 and 02 December. Meanwhile, only gas was emitted from the summit area of the New Southeast Crater. Explosive activity could not be detected.
On 30 November, INGV reported that the lava flow at the New Southeast Crater had reached a few hundred metres in length. Furthermore, it was reported that the source of the tremor was located between Southeast Crater and Bocca Nuova at an altitude of 2000 - 2600 m. Infrasound activity at the summit craters was low and concentrated at Bocca Nuova. No noticeable ground deformations were recorded at the volcanic edifice [1].
The tremor fluctuated at a medium level until 29 November, reaching nearly high levels only on 19 and 27 November. On 29 November, tremor began to rise rapidly and remained just at a high level until 30 November. Afterwards, the tremor oscillated between medium and high intensity several times and stabilised at medium level from 01 December [2].
On 19.11. a quake of magnitude 1.5 occurred east of Monte Nero (NE flank). On 19.11. a quake of magnitude 1.6 was measured northwest of Piano Pernicana (NE flank). On 25.11. two quakes occurred in Piano Pernicana, reaching magnitudes of 1.7 and 1.9 respectively. On 25.11. a quake of magnitude 2.1 occurred west of Randazzo (NW flank). On 28.11. a quake of magnitude 1.5 was recorded near Randazzo [3].
My interpretation of the data and speculations about the further development:
Now the magma has managed to make its way to the surface of Etna after all. After the presumed magma rise on 15 November, which I speculated about in my last update, the pressure in the mountain must have become a bit too great. Since the lava seems to flow out very quietly and there has been no explosive activity in the summit area of the Southeast Crater complex so far, it is probably already relatively strongly degassed magma. It has probably been rising for months (since the end of the last eruption in June) and is being degassed via Bocca Nuova. The recent increase in seismic activity, especially in the area of the Pernicana fault, may indicate that magma has accumulated in the area to the east of the summit craters and/or beneath the northeastern rift system. This has now created a path upwards and is likely to emerge until the pressure inside the mountain is equalised again. Since the vent is still relatively far up and will not be very large, I do not think a prolonged eruption is to be expected. However, it could happen that new effusive vents open further north or northeast, which would then also be located on somewhat lower altitude. Then a longer eruption is also conceivable. Of course, the magma rise can intensify at any time, or fresh and gas-rich magma can ascend. This would be a game changer. At the moment, however, there are no indications of this.
So I think it is most likely that the quiet and low lava production will continue for a few more days and that the narrow lava flow will gradually pour into the Valle del Leone.
[1] INGV-Sezione di Catania. 2022. Comunicati attività vulcanica. 30/11/2022 12:56 - COMUNICATO ETNA
[2] INGV-Sezione di Catania. 2022. Home. TREMORE VULCANICO. ECNE
[3] INGV. Osservatorio Etneo. Sorveglianza e Monitoraggio. DATABASE TERREMOTI. Localizzazioni di sala operativa. 2022.
