Update on Etna's activity, 15 November 2010

Ash emissions from the Northeast Crater, seen from Trecastagni at sunset on 14 November 2010

Aerial view of the Northeast Crater taken about noon on 14 November 2010. A dilute ash plume can be seen rising from the crater, and patches of snow on the crater rims are covered with thin ash deposits. Photo taken by Alfio Amantia (INGV-CT)

The floor of the Northeast Crater with the open intracrater vent, which has considerably increased in diameter since the previous visit to the crater in October 2010. Brownish ash is being emitted from the vent, and ash deposits can be seen both on the inner crater walls as well as on the surface in the foreground. Photo taken on 15 November 2010

Following several days of minor ash emissions from the Northeast Crater - the tallest of the four summit craters of Etna, hereafter "NEC" - on the morning of 14 November 2010 there was a significant increase in both the frequency and in the volume of ash emissions from the same crater. These emissions generated plumes a few hundred meters high, which were then carried by the wind as a long, narrow trail, first toward southwest (14 November), then toward northeast (during the night of 14-15 November), and finally toward east (15 November). The emissions occurred in an intermittent manner, alternating with periods of white gas and vapor emissions.

A visit to the summit craters was carried out by  INGV-Catania staff on 15 November 2010, to make direct observations of the NEC activity and of the character of the ash deposits in the surrounding areas. Near the NEC cone, particularly to the south, in the northern portion of the Voragine, a few millimeters of brown ash were present on the ground. On the rim of the NEC itself, the deposit was up to 1 cm thick, especially on the eastern side. During the stay on the NEC rim, the ash emissions were rather modest, and accompanied by nearly continuous deep rumblings, sometimes becoming louder.

Since more than a year, on the crater floor there had been an open degassing vent, which until the previous visit to the NEC in October had a diameter of about 25 m. On 15 November, this vent was seen to be much larger, with a diameter of at least 75 m. Ash emissions from this vent occurred at times in a passive manner, but at times became more vigorous. The inner walls of the crater were covered by reddish brown ash deposits. No coarse-grained material was observed, neither in the deposits, nor in the emissions.