After a quiescent interval of 23 days, the New Southeast Crater (New SEC) of Etna reactivated on the morning of 15 November 2011 to produce its 18th paroxysmal eruptive episode since the beginning of this year. This episode has in nearly all details been a repetition of its predecessors, though with a few minor variations; the culminating phase lasted about one hour and terminated rather abruptly. Ash and lapilli falls affected the southeastern flank.
The first signs of renewed eruptive activity at the New SEC were observed, by means of the thermal monitoring camera of the INGV-Osservatorio. This anomaly slowly grew both in temperature and area, and was caused by the emission and expansion of a small lava flow that was being emitted from the lower end of the fissure.
This activity continued for the next nearly 3 hours, while increasing very slowly, and the lava flow spread out into several branches at the southeastern base of the cone, advancing only a few hundred meters.At about 10:55 GMT, the activity showed a marked and rapid increase both within the crater and along the external eruptive fissure, and shortly after 11:00, lava fountains rose from the crater, accompanied by intensifying ash emission. Shortly thereafter, also the southeast flank fissure vents began producing lava fountains, and the cone was immediately subjected to heavy fallout of bombs and scoriae.At about 11:30 GMT the emission of ash significantly increased, especially from a vent located in the southeastern portion of the New SEC, and a column of ash and gas rose several kilometers above the summit of Etna before being bent southeastward by the wind. The phase of most intense activity occurred between 11:45 and 12:15 GMT, when jets heavily charged with incandescent bombs reached heights of about 800 m above the crater. This pyroclastic material poured down onto the New SEC cone and well beyond its base, and also showered the nearby old SEC cone.At about 12:25 GMT, the eruptive activity started to diminish, and then abruptly ceased at 12:29, to be followed by passive ash emission that lasted until shortly after 13:00. Weak and discontinuous spattering accompanied by slow lava effusion continued for a few hours from a single vent in the central portion of the eruptive fissure on the southeast flank of the New SEC cone.
The New SEC cone underwent further growth in height, mostly on its southern side, where at least 10 m of new material accumulated bringing the total height of the cone to about 180-200 m above its base.
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