Seismicity has continued since Etna's SE-flank fissure eruption in late December. The following is from R. Romano. "Beginning 1 February, a series of shocks occurred on all ... flanks (table 2). The most energetic events occurred 1 and 2 February ~ 15 km SE of the summit (in the Dagala zone, in the area of Santa Venerina and Linera), with magnitudes between 3.0 and 3.6 and depths within 1 km. During the week, 50 shocks were also recorded by instruments, mainly on the E flank."

Table 2. Largest of a series of earthquakes on Etna's flanks, February 1986.

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.