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Etna update, 8 October 2012

Video frame captured from footage recorded by the high-sensibility visible monitoring camera of the INGV-Osservatorio Etneo on the Montagnola (EMOH) during the culmination of the Strombolian activity within the Bocca Nuova, at 03:17 GMT on 7 October 2012. The yellow circle highlights a few incandescent bombs being launched well above the crater rim.

On the evening of 2 October 2012, weak Strombolian activity resumed within the Bocca Nuova, the largest of the summit craters of Etna. The site of the activity was the same vent in the southeastern portion of the crater floor, which had already been active in July-August 2012. On 3 October, the Strombolian activity was accompanied by the emission of a small intracrater lava flow toward the southern part of the crater floor. During the following days, the activity slowly intensified, and began to construct a new pyroclastic conelet on top of the ruins of the cone formed in July-August, which had subsequently nearly completely collapsed. On the evening of 6 October, the volcanic tremor amplitude showed a rapid increase, and at the same time the eruptive activity intensified, with emission of a new, well-fed lava flow toward the western part of the crater floor, and vigorous Strombolian activity that often took the character of a pulsating lava fountain. Both the intensity of the eruptive activity and the volcanic tremor amplitude reached a peak shortly after midnight on 7 October, and strong glow was seen over the summit from nearby populated areas. Some of the lava jets rose well above the elevation of the crater rim, especially during the final phases of the activity, which from 03:30 GMT on showed a marked diminution. Contemporaneously, the volcanic tremor amplitude decreased, and on 8 October dropped to the lowest levels recorded for many weeks.

The previous period of eruptive activity at the Bocca Nuova began on the evening of 2 July 2012 with small Strombolian explosions followed by more continuous activity accompanied by the emission of small intracrater lava flows, which continued until 24 July. During this interval, a new pyroclastic cone grew around the single eruptive vent, which reached a height of about 50 m above the surrounding crater floor; furthermore the deeper portions of the crater floor were filled with new lava. From 26 July until 11 August, five episodes of more intense Strombolian and effusive activity took place, which led to further filling of the crater floor. After the latest of these episodes, there were frequent small emissions of ash, at times accompanied by the expulsion of lithic blocks; this activity ceased on 25 August 2012.