Strong explosive eruption at Etna volcano, Italy

A strong explosive eruption started at Etna volcano on December 13, 2020, ejecting volcanic ash up to 4.8 km (16 000 feet) above sea level by 23:00 UTC. The Aviation Color Code was raised to Red.

Monitoring networks observed increased strombolian activity at the SE Crater starting at 19:20 UTC on December 13, INGV's Etna Observatory reported.

At the same time, there was a sudden increase in the magnitude of the volcanic tremor that has risen from average to high levels, the observatory said at 22:22 UTC, adding that the amplitude is still growing.

In addition, an increase in infrasonic activity has been observed both in the number and amplitude of infrasonic events.

Two eruptive fissures opened on the southeastern side of the SE Crater, producing two lava flows propagating towards the S and SW, whose fronts remained confined to an altitude of about 2 850 m (9 350 feet) a.s.l. Three pyroclastic flows were observed at 22:15 and 22:16 UTC.

Surveillance cameras showed a significant decrease in explosive activity at 22:50 UTC, with variable levels over the next 4 hours.

Explosive activity decreased by 07:05 UTC on December 14, with weak ash emissions still ongoing. The Aviation Color Code was lowered to Orange at 07:06 UTC.

Geological summary

Mount Etna, towering above Catania, Sicily's second-largest city, has one of the world's longest documented records of historical 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 (5.1 x 6.2 miles) horseshoe-shaped caldera open to the east.

Two styles of eruptive activity typically occur at Etna. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more of the three prominent summit craters, the Central Crater, NE Crater, and SE Crater (the latter formed in 1978). 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. (GVP)

Featured image credit: Boris Behncke