Steady degassing from the summit craters followed the end of the 1991-93 eruption on 30 March (18:03). Increased gas emissions were noted at the central (Voragine) and SE craters (see figure 59) in April, but no morphological changes were detected. The floor of Northeast Crater sank a few meters in early April and remained obstructed by fallen material.

Seismic activity was low with only two volcano-tectonic events recorded. The highest magnitude event (M 2.7) occurred 14 April on the SE flank of the volcano at ~ 10 km depth. Long-period events were similar to those recorded in March, but fewer in number. There was also a decreasing trend in volcanic tremor spectral amplitude. No major changes were recorded by shallow bore-hole tilt stations on the slopes of the volcano.

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: IIV.