INGV reported that activity at Etna’s summit craters continued during 14-23 July. Explosive activity at both Voragine Crater and NE Crater began to slowly intensify at around 1500 on 14 July and ash emissions from both craters rapidly dispersed. Infrasound data showed increasing activity at NW Crater at around 1600.

Strombolian activity at Voragine Crater persisted on 15 July, and that same day minor ash emissions from Voragine and NE craters were visible in webcam images. Volcanic tremor amplitude values fluctuated at average values for most of the day, then began to increase. Activity at Voragine was observed in infrasound data. Strombolian activity at Voragine slowly intensified beginning around 2100 and volcanic tremor amplitude reached very high levels, peaking at 2140. Activity continued to intensify, and lava fountaining began at 2154. Ash plumes reached about 6 km a.s.l., or about 2.6 km above the summit, and drifted SE. Ashfall was reported in areas downwind including Viagrande (16 km SSE) and Aci Castello (26 km SSE). Lava flowed over the NW rim of Bocca Nuova Crater and descended to about 3,000 m elevation. The average volcanic tremor amplitude remained at very high levels and peaked again at 0100 on 16 July. Infrasound data showed a decrease in the frequency of events. Lava fountaining decreased and had ceased by 0210 on 16 July, though Strombolian activity persisted until around 0500. Reddish ash plumes occasionally rose from NE Crater throughout the day. Strombolian activity at NE Crater began at around 2300 and ejected large bombs several tens of meters above the crater rim. The lava flow continued to be fed though at a low rate.

INGV staff visited the summit area on 17 July and saw Strombolian activity in NE Crater; the activity was also visible in webcam images. The activity produced both fine and coarse material that was ejected tens of meters above the crater rim; the coarser material fell back inside the crater as well as onto the flanks. An explosion at NE Crater at 1956 produced an ash plume that rapidly dispersed.

Strombolian activity at Voragine Crater was again visible in webcam images on 22 July, though weather clouds mostly obscured observations. Volcanic tremor amplitude was low, though gradually increasing, through the day; the amplitude reached a high level by 1745 and remained high. Infrasound data indicated activity in Voragine. The Strombolian activity intensified and was characterized as strong by 0300 on 23 July. Ash emissions rose about the summit, volcanic tremor amplitude increased to very high levels, and by 0508 lava fountaining was underway that resulted in overflows of the Bocca Nuova Crater W rim. Lava fountaining persisted and by 0830 fountains were rising several hundred meters above the crater rim. Ash plumes rose around 8 km a.s.l., or about 4.6 km above the summit, and drifted ESE, then SSE. Ashfall was reported in Rifugio Sapienza (5 km S), Piano Vetore (6 km SSW), C.da Milia, Nicolosi (15 km S), Tremestieri Etneo (20 km SSE), and Catania (29 km SSE). The lava fountaining gradually decreased and then ceased by 1015. The lava flow produced during the activity was small, though due to weather clouds the total length was undetermined.

Geological Summary. Mount Etna, towering above Catania on the island of Sicily, has one of the world's longest documented records of volcanism, dating back to 1500 BCE. Historical lava flows of basaltic composition cover much of the surface of this massive volcano, whose edifice is the highest and most voluminous in Italy. The Mongibello stratovolcano, truncated by several small calderas, was constructed during the late Pleistocene and Holocene over an older shield volcano. The most prominent morphological feature of Etna is the Valle del Bove, a 5 x 10 km caldera open to the east. Two styles of eruptive activity typically occur, sometimes simultaneously. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more summit craters. Flank vents, typically with higher effusion rates, are less frequently active and originate from fissures that open progressively downward from near the summit (usually accompanied by Strombolian eruptions at the upper end). Cinder cones are commonly constructed over the vents of lower-flank lava flows. Lava flows extend to the foot of the volcano on all sides and have reached the sea over a broad area on the SE flank.

Source: Sezione di Catania - Osservatorio Etneo (INGV)