Etna update, 16 July 2011

Strombolian activity from a single vent located in the southeastern portion of the Bocca Nuova (at right), and a lava flow (at left) that issues from underneath a cover of pyroclastic material deposited by the Strombolian activity. The lava descends into a depression in the central-western portion of the Bocca Nuova. Photo taken on the evening of 15 July 2011 by Boris Behncke (INGV-Catania) from the south-southeastern rim of the Bocca Nuova

On the morning of 16 July 2011, a series of ash emissions from the active crater located on the eastern flank of the Southeast Crater cone marked the resumption of explosive activity within this crater, which produced loud booming sounds that were widely heard in populated areas on the slopes of Etna. This activity is occurring only one week after the latest paroxysmal episode, which took place at the same crater. Further updates on the evolving situation will be posted soon.

At the same time, the Strombolian activity initiated on the evening of 11 July within the Bocca Nuova is continuing with slight fluctuations; during a field visit by INGV staff (Salvatore Giammanco e Boris Behncke) on the evening of 15 July, the Strombolian activity appeared slightly diminished compared to that observed two evenings before, but within one-and-a-half hours, the activity increased to levels superior to those observed on 13 July. Furthermore, immediately to the west of the explosive vent, a lava flow was observed, which was oozing from underneath a sheet of pyroclastics that were constantly deposited by the nearby Strombolian activity. The flow then cascaded into a deeper depression in the central-western portion of the crater floor. Dense gas clouds and the intense explosive activity precluded more detailed observation of this lava flow.

The most recent effusive activity within the Bocca Nuova occurred in the fall of 1999, when lava and a complex of large pyroclastic cones completely filled the crater, leading to a series of lava flows from the western rim of the Bocca Nuova and down the western flank of Etna to a distance of 4.2 km.

A zoomed view onto the active lava flow on the floor of the Bocca Nuova; to the right is the zone where the lava is oozing from a pyroclastic deposit constantly laid down by the Strombolian activity from the explosive vent nearby, ripping gaping fissures into the deposit. To the left, the lava is forming a cascade as it descends into a deeper depression in the central-western portion of the crater floor. Photo taken on the evening of 15 July 2011 by Boris Behncke (INGV-Catania) from the south-southeastern rim of the Bocca Nuova