Etna update, 23.12.2022:

During the past 14 days, the eruption at the base of New Southeast Crater has continued. The lava flow has increased significantly in length over the last few days and is on its way to the Valle del Bove. The tremor remained elevated and gas emissions at the summit craters have also increased.

In the last two weeks, clouds often hindered the observation of Etna's summit area by webcams. At times, however, gaps in the clouds allowed a view of the eruptive activity. During the past 14 days, lava emission continued at the northeastern base of New Southeast Crater. The lava flow continued to move in a northeasterly to northerly direction and poured into the Valle del Leone. Its front continued to advance in a northerly direction. From 15 December onwards, it reached the bottom of the Valle del Leone at an altitude of about 2500 - 2600 metres. In the following days, it crossed the shallowly sloping valley floor and slowly approached the edge of the Valle del Bove. On 21 December, the lava began to flow down the steep slope of the Valle del Bove. By the evening of 23 December, the front had reached about 2200 m high terrain and was located southwest of Monte Simone.
In the meantime, below the effusive vent, a fan-shaped lava field developed consisting of several narrow flows that kept changing their position slightly.
Furthermore, I did not observe any explosive activity at the effusive vent or at the South East Crater complex. In the summit area of New Southeast Crater, only fumaroles continued to release gas.
Meanwhile, Bocca Nuova experienced vigorous and often pulsating gas emission. Hardly any gas emission was visible at Northeast Crater and Voragine.

As the INGV reports, hornitos have developed above the effusive vents. At times, there is also weak explosive activity there associated with the ejection of incandescent lava fragments. Within the lava field, some temporary vents have formed, feeding narrow lava flows. Using MODIS/VIIRS satellite data, the volume of lava released so far has been estimated at 500,000 - 1,000,000 m3 [1].

The evaluation of the data from the GPS stations showed further inflation of the volcano structure in the last 7 days, which was recorded in particular by the stations on the central western flank. In contrast, the stations in the summit region did not record any significant changes [1].
The clinometric data did not show any significant changes regarding the slope on the mountain flanks during the past week [1].

Infrasound activity at the summit craters was weak to moderate in the period from 07 to 18 December. Most of the events were registered on 18 December, although the measurements were disturbed by strong winds on some days. The source of the activity was Bocca Nuova [1].

Sulphur dioxide emissions from the summit craters continued to increase between 6 and 18 December. The daily emission rates reached high levels.
Ground carbon dioxide emissions (ETNAGAS station) remained at a medium level between 06 and 18 December [1].

The online seismograms of station ECNE were overlaid by noise during the past week, which was caused by the persistently increased tremor [2].
The tremor has been at a medium level for the last 14 days, with only slight fluctuations. Most recently, there was a slight upward trend [2].
The source of the tremor was in the area between the southeast crater and Bocca Nuova at an altitude of between 2000 and 2800 m. In addition, a narrow tremor track in a westerly to southwesterly direction was observed, leading up to an altitude of about 2500 m - 2750 m and ending in the region above the Galvarina area [1].

On 18.12. a quake of magnitude 1.8 was registered west of Monte Parmentelli (southwest flank). On 18.12. two quakes occurred west of Moio Alcantara (north flank), the strongest having a magnitude of 1.6. On 19.12. an earthquake of magnitude 2.3 was recorded at Monte Zoccolaro (southeast flank). On 21.12. a quake with a magnitude of 1.6 occurred north of Monte Centenari (eastern flank) [3].

My interpretation of the data and speculations about the further development:
Interesting in the tremor data is a track that leads from the depth of the mountain in a southwesterly to westerly direction and ends at an altitude of approx. 2500 - 2750 m. It almost looks as if magma rose in this area, but then did not make it to the earth's surface. Unfortunately, the INGV does not refer to this measurement data in the report, so it remains unclear what really happened there. Otherwise, the second week of December showed a further increase in sulphur dioxide emissions at the summit craters, which indicates that more magma was degassing than in the weeks before. Certainly, only part of the rising magma is being released by the current eruption, as the inflation of the volcanic edifice has also continued to increase. Thus, a continuation of the effusive activity at the New Southeast Crater can be expected in the next days to weeks.

1 - INGV-Sezione di Catania. 2022. Etna - BOLLETTINO SETTIMANALE - SETTIMANA DI RIFERIMENTO 12/12/2022 - 18/12/2022
2 - INGV-Sezione di Catania. 2022. Home. TREMORE VULCANICO. ECNE
3 - INGV. Osservatorio Etneo. Sorveglianza e Monitoraggio. DATABASE TERREMOTI. Localizzazioni di sala operativa. 2022.

Photo by INGV

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