Activity resumed during the night of 1-2 September, with a collapse of part of the wall of Bocca Nuova and small explosions from the neighboring summit crater, the Chasm, the following day. The volcano then remained quiet until a 30-second explosion from Bocca Nuova killed nine persons and injured 23 at 1747 on 12 September. Some of the 150 tourists in the area at the time of the explosion were on the crater rim, and others were at a parking lot 400 m to the NW, where a large number of blocks about 25 cm in diameter fell. The explosion was apparently somewhat directed, because the distribution of blocks was dominantly to the NW of Bocca Nuova and no blocks traveled as far as 200 m in directions other than NW. No fresh magma was ejected by the explosion. The next day, considerable quantities of fine ash were emitted from Bocca Nuova and one or two small deep explosions were heard, but activity since then has been limited to weak emission of vapor containing SO₂.

Further Reference. Kieffer, G., 1981, Les explosions phreatiques et phreatomagmatiques terminales a l'Etna: BV, v. 44, p. 655-660.

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: J. Guest, Univ. of London; UPI.