Activity resumed on Etna's SE flank during the night of 24-25 August. The initial activity consisted of ejection of spatter bombs and ash from one of the 1971 eruption craters, at 3,000 m altitude on the SE flank of the summit cone. Lava extrusion from this crater began the night of 25-26 August and had ended by the next morning. Lava flowed eastward into the Valle del Bove, traveling 2.5 km to 2,000-2,100 m elevation. During the afternoon of the 26th, a second vent opened at 2,725 m altitude, on the wall of the Valle del Bove. Its flow moved 3 km in 12 hours, reaching 1,650 m altitude.

The explosive activity that started 24-25 August began to decrease on 27 August, but 7 more vents opened that afternoon on the walls of the Valle del Bove, between 2,800 m and 2,500 m. By 29 August, the number of active vents had decreased to four with a notable diminution of lava effusion, and explosions had ended.

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.

Information Contacts: R. Romano, IIV.