A small vent at Etna’s Southeast Crater began emitting unprecedented quantities of volcanic gas puffs that formed vortex rings during the evening of 2 April. INGV issued a Volcano Observatory Notice for Aviation (VONA) at 2016 on 2 April raising the Aviation Color Code to Yellow (the second highest color on a four-color scale) due to increased signs of unrest. The Aviation Color Code was raised to Orange at 2030 because explosive activity at the summit craters was visible in webcam images; ash emissions were not produced.

A series of six explosive events were recorded by the seismic network during 1501-1510 on 7 April. Coincident with the seismic signals a four-minute-long, dense ash emission from Bocca Nuova Crater rose to 5 km a.s.l., or about 1.6 km above the summit, and quickly dispersed to the S. A VONA issued at 1018 on 9 April noted sporadic activity at the summit craters.

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.

Source: Sezione di Catania - Osservatorio Etneo (INGV)