Etna update, 03/02/2023

Last week, the effusive vent at the northeast base of Mt Etna's New Southeast Crater continued to release lava. However, the flowrate fluctuated significantly.
On 28.01., the front of the lava flow initially stagnated at about 2300 m altitude. On 29.01. it retreated to the rim of Valle del Bove at about 2500 m, but during the day a new partial flow developed, which now took a slightly more southerly course. On January 30, the southern branch descended a few hundred meters down the escarpment of Valle del Bove, and the northern branch also became better fed. On January 31, the flows stagnated or retreated again. On the other hand, the southern stream was well fed on 01 February and widened significantly. During the night of February 02, the lava flow decreased significantly and during the day practically no strong thermal anomalies were visible. Towards evening, however, a new surge of lava set off again. Today, the new lava flow continued to move slowly northward through the Valle del Leone.
Meanwhile, in the summit area of the New Southeast Crater, gas was emitted persistently, but in contrast to the previous week, only few ash was visible. Instead, pulsating glow was visible in the upper northern section of the cone during the nights on light sensitive webcams. Presumably, the escaping steam was illuminated from below, from the depth of the vent. Whether this was caused by deep-seated explosions or simply by heat remained unclear.
During last week Bocca Nuova released the most gas of the summit craters. Again, the emissions were pulse-like enhanced and at least once a gas ring was observed. At Voragine and Northeast Crater only weak gas emission was visible.

As reported by INGV, a volume of 4.4 to 5.6 million m3 of lava was emitted by January 29. This occupied an area of about 880,000 m2 [1].

The analysis of the data from the GPS stations showed no significant changes for the period between January 23 and 29. However, the slight deflation already observed in recent weeks continued [1].
Clinometric data showed no significant changes between January 23 and 29 [1].

The measurement of infrasound activity at the summit craters in the period between January 23 and 29 showed a low number of events. However, there was a slight increase in explosive activity in the last days. The source of the events was the Bocca Nuova [1].

Sulfur dioxide emissions at the summit craters were at intermediate levels during the period between 23 and 29 January.
Ground carbon dioxide emissions (station ETNAGAS) decreased slightly between 23 and 29 Jan, reaching low levels [1].

Weak long-period signals were occasionally visible on the online seismograms of station ECNE during the past week [2].
The tremor fluctuated in the lower range of the mean level during the last week and was subject to a slight increasing trend during the last days [2].
As reported by INGV, the source of the tremor in the period between 23 and 29 January was at about 2400 - 2800 m altitude in the area below Southeast Crater [1].

On 28.01. an earthquake of magnitude 1.7 was registered at Pizzi Deneri (northeast flank). On 02.02. an earthquake of magnitude 2.0 occurred at Pozzillo (eastern flank) [3].

1 - INGV-Sezione di Catania. 2023. Etna - BOLLETTINO SETTIMANALE - SETTIMANA DI RIFERIMENTO 23/01/2023 - 29/01/2023
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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