INGV reported that during 11-17 January activity at Etna was characterized by intra-crater Strombolian activity at Northeast Crater (NEC), occasional ash emissions from the Voragine (VOR) and Bocca Nuova (BN) craters, and Strombolian activity, lava effusion, and ash emissions at the Southeast Crater (SEC).
In general, the activity was similar to the pervious week, though activity at SEC on 18 January was notable.
Lava effusion began around 0700 on 17 January but was confined to the SEC summit cone.
At around 0740 the lava breached the crater and lava flowed down to the base of the cone.
The effusion rate increased by 0819 and an ash emission was possibly visible; the lava flow lengthened and had reached an elevation of 3,000 m by 1000.
Weather clouds moved in and prevented visual observations until 1830 on 18 January when the lava flow was visible again; it was no longer being fed and was cooling.
Volcanic tremor amplitude increased and Strombolian activity intensified at 2000.
A new lava flow emerged at 2015 and traveled towards the Valle del Bove, reaching an elevation of 2,900 m.
Low lava fountains were visible at 2130 and an ash plume drifted ESE, causing ashfall on the downwind flank.
Lava flows descended the SE, E, and NE flanks of the SEC.
Explosive activity significantly decreased at 2200.
Two distinct lava flows were visible, with one heading N and the other moving towards the Valle del Bove.
Tremor and infrasound signals decreased to pre-episode levels by 2230.
The the lava flows were stable and cooling on 19 January.
Source: Sezione di Catania - Osservatorio Etneo (INGV)