On 13 July the 16th eruptive episode in 2001 took place at the NNE vent of Etna's Southeast Crater. During the 4-hour-long episode, lava flows, Strombolian activity, and several earthquakes occurred. The largest two earthquakes had magnitudes of 3.9 and were felt 15 km away in the town of Nicolosi. The Toulouse VAAC reported that a small ash cloud was visible on the Sistema Poseidon Etna webcam and on satellite imagery. It did not rise above 3.7 km a.s.l.

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.

Sources: Toulouse Volcanic Ash Advisory Centre (VAAC), Associated Press, Etna Volcan Sicilien (Charles Rivière), Sezione di Catania - Osservatorio Etneo (INGV)