Etna update, 10/02/2023

Effusive activity at the northeastern base of Mt Etna's New Southeast Crater ended last week. However, the tremor has weakened only slightly and seismic activity has increased somewhat.

On 04 February, the effusive vent at the northeast base of New Southeast Crater continued to feed a lava flow. This moved northward through the Valle del Leone. On the evening of 04 February, a partial flow began to descend the steep western slope of Valle del Bove. During the night of 05 February, its front descended to an altitude of about 2300 m and moved in the area southwest of Monte Simone. In the morning of 05 February, the partial flow did not seem well fed and began to retreat. Bad weather hindered further observation until 06 February. Then, in the morning of 06 February, the entire lava field was inactive. The same picture was seen on the following days, with observations increasingly hindered by clouds and fresh snow.
At New Southeast Crater, the northern summit area showed weak pulsating glow during the nights until 05 February, apparently caused by deep-seated explosions. Gas and steam were also persistently emitted from the summit area of New Southeast Crater.
At Bocca Nuova, strong and often pulsating gas emission continued. At the other summit craters, only weak gas emissions occured.

As reported by INGV, a volume of 4.8 to 6.1 million m3 of lava was emitted by February 03. This occupied an area of about 960,000 m2 [1].

Analysis of the data from the GPS stations showed no significant changes for the period between 30 January and 05 February, but the trend toward slight deflation of the volcanic edifice that began in mid-December continued [1].
Clinometric data showed no significant changes in the slopes of the volcanic edifice between January 30 and February 05 [1].

The measurement of infrasound activity at the summit craters showed an increase in events between 30 Jan - 05 Feb compared to the previous week. However, the measurements were at times affected by strong winds. The source of the activity was Bocca Nuova and Southeast Crater [1].

Sulfur dioxide emissions at the summit craters increased somewhat during the period between 30 Jan and 05 Feb and were at intermediate levels.
Ground carbon dioxide emissions (ETNAGAS station) fluctuated at low levels between 30 Jan and 05 Feb.
The concentration of helium isotopes (3He/4He - ratio) in the Etna area, last determined on 03 Feb, was comparable to the last measurements with a value of 0.63. The measured value was on a high level [1].

On the online seismograms of station ECNE, weak long-period signals were visible every few minutes during the past week.
The tremor decreased slightly on 04 February and since then has been just above the boundary between low and medium levels [2].
As reported by INGV, the source of the tremor in the period between 30.01. and 05.02. was at about 2000 - 2800 m altitude in the area below the central crater [1].

On 05.02. a small series of earthquakes occurred in the area northwest of Adrano (western flank). The strongest tremors reached magnitudes of 2.5 and 3.7, respectively, and occurred at depths between 12 and 15 km. On 06.02. an earthquake of magnitude 1.6 was recorded near Biancavilla (southern flank) [3].

1 - INGV-Sezione di Catania. 2023. Etna - BOLLETTINO SETTIMANALE - SETTIMANA DI RIFERIMENTO 30/01/2023 - 05/02/2023
2 - INGV-Sezione di Catania. 2023. Home. TREMORE VULCANICO. ECNE
3 - INGV. Osservatorio Etneo. Sorveglianza e Monitoraggio. DATABASE TERREMOTI. Localizzazioni di sala operativa. 2023.

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