Etna update, 05/05/2023

Bad weather with many clouds and fresh snow often hindered the observation of the summit craters by webcams during the last days. In the days before or during the cloud-free hours, it became apparent that the most gas continued to be emitted at Bocca Nuova. Emissions were also frequently pulse enhanced. At the Southeast Crater complex, fumaroles along the walls in the upper part of the fracture (large breach), released gas persistently. Gas or white steam was also persistently emitted along fractures on the upper north flank of New Southeast Crater. During the nights, light-sensitive webcams showed a small glowing spot in this area. Beginning on April 23, white steam was also emitted more frequently on the upper northeastern flank of New Southeast Crater, in an area just north of the east flank breach. In the following nights, another glowing spot was then visible here. Presumably, a new fracture had formed in this area, releasing heat and steam. Steam was also released there persistently on subsequent days. At Voragine and Northeast Crater I could still not detect any significant gas emission.

Analysis of the GPS station data showed no significant changes for the month of April [1].
Clinometric data showed no significant changes in the slope of the volcanic edifice in April [1].

The measurement of infrasound activity at the summit craters showed a low number of events in April. The amplitude of the events was at low to medium-low levels [1].

Sulfur dioxide emissions at the summit craters were at medium levels in April. They declined during the month after peaking in early April.
Ground carbon dioxide emissions (ETNAGAS station) fluctuated at low levels in April [1].
The concentration of helium isotopes (3He/4He - ratio) in the Etna area, last determined on 04 April, was slightly higher than in the last measurements with a value of 0.61. The measured value reached high level [1].

The online seismograms of the ECNE station showed occasional, weak long-period signals during the last two weeks. In the last days, their frequency increased somewhat [2].
The tremor initially hovered just above the low-mid level boundary during the last 14 days, but then gradually increased and is now hovering at higher-mid level [2].
In April, the source of the tremor was located between Bocca Nuova and Southeast Crater complex at an altitude of 1500 - 2900 m [1].

On 28.04. an earthquake of magnitude 2.0 was registered northwest of Monte Maletto (northwest flank). On 01.05. an earthquake of magnitude 1.6 occurred southeast of Zafferana Etnea (southeast flank). On 03.05. an earthquake of magnitude 1.6 was registered west of Monte Intraleo (west flank). Between 04.05. and 05.05. several earthquakes were recorded at Monte Centenari (eastern flank). The strongest quake had a magnitude of 2.1 [3].

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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