Etna update, 17/02/2023

During the past week, Mt Etna remained relatively quiet, with the usual gas releases from Bocca Nuova and the Southeast Crater complex. Deep-seated explosions probably occurred in Bocca Nuova. The tremor still remained somewhat elevated. Seismic activity, however, was low.

Last week, initially very bad weather with large amounts of snow and storms prevented the observation of Etna by webcams. Even after an improvement in the weather from 14 February, many cameras were still down. The available webcams showed that lava was still not being produced at the New Southeast Crater. There was continued emission of gas and steam in the summit area of the cone. During the nights, faint glow smoke was visible just below the northern rim of the crater. A fumarole field is located here, as well as fractures and a former vent that was active during the May/June 2022 eruption.
Otherwise, Bocca Nuova continued to release gas vigorously and in pulses. During the night of 16 February, faint glow was sporadically visible above the summit crater by means of light-sensitive webcams. Last night, the glow intensified and became more frequent. Probably deep-seated explosions occurred. I was still unable to detect any significant gas emission from the northeast crater and Voragine.

The evaluation of the data from the GPS stations showed no significant changes for the period between 06 and 12 February [1].
The clinometric data did not show any significant changes in the slope of the volcano building between 06 and 12 February [1].

The measurement of infrasound activity at the summit craters was strongly disturbed by very bad weather in the period from 06 to 12 February. Overall, there was a slight decrease in infrasound activity. The source of the events was Bocca Nuova [1].

Sulphur dioxide emissions at the summit craters increased somewhat in the period between 06.02. and 12.02. and were at a medium level.
Ground carbon dioxide emissions (ETNAGAS station) increased slightly between 06.02. and 12.02. and reached near-medium levels [1].

The online seismograms of station ECNE showed only single weak signals last week, after initial interruption due to bad weather [2].
The tremor fluctuated on the border between low and medium level during the past week [2].

On 13.02., a quake of magnitude 1.9 was measured south of Monte San Leo (southern flank) [3].

My interpretation of the data and speculations about the further development:
So now the effusive activity at the northeastern base of New Southeast Crater, which started at the end of November 2022, has come to an end again. This was already indicated from mid-January, when the production rate began to show greater fluctuations. A total of about 6 million m3 of lava was produced, which is a relatively small amount in comparison. Analyses of the lava produced in December showed that it was more highly developed material, which was also evident from the low explosive activity. The magma had probably been stored in the mountain for some time and was able to degas via the summit craters. Then it found an outlet at the end of November and an eruption occurred. Probably also because the mountain slowly expanded due to the rising magma and probably more magma rose than could be stored within the volcanic structure. The still high readings for the helium 4 isotope show, in my opinion, that there is still plenty of fresh magma flowing in under the mountain. A small part of it will probably continue to rise in the mountain and sooner or later lead to new eruptive activity. It is not yet possible to say what this will look like. It is quite possible that the quiet eruptive activity of last winter will be repeated in a few months. However, if more gas is involved or if this has no possibility of degassing, there may also be strombolian explosions at the Southeast Crater complex. A new phase of paroxysmal eruptions cannot be completely ruled out either. So let's just be surprised what the old lady has in store for us this time!

1 - INGV-Sezione di Catania. 2023. Etna - BOLLETTINO SETTIMANALE - SETTIMANA DI RIFERIMENTO 06/02/2023 - 12/02/2023
2 - INGV-Sezione di Catania. 2023. Home. TREMORE VULCANICO. ECNE
3 - INGV. Osservatorio Etneo. Sorveglianza e Monitoraggio. DATABASE TERREMOTI. Localizzazioni di sala operativa. 2023.

Photo by INGV Catania

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