Activity of the Sicilian volcanoes during March 2011
ETNA
During March 2011, Etna remained relatively calm until the 29th, when small ash emissions resumed from the crater located on the eastern flank of the Southeast Crater (SEC) cone. For the entire month, strong degassing was observed at the Northeast Crater (NEC) and the Bocca Nuova, and deep-seated explosions continued within the conduit of the NEC.
On the forenoon of 29 March, the monitoring video cameras of the INGV-Catania recorded a small burst of gas and ash from the crater on the east flank of the SEC cone. Signals indicating similar events were subsequently recorded by the infrasonic network in the summit area. These events continued during the following days at varying intervals, and on 31 March occurred every 10-15 minutes. The plumes of gas and ash rose only a few tens of meters above the rim of the crater before being displaced by the wind. Video footage of the thermal camera at the Montagnola (EMOT) revealed the presence, in some of these emissions, of hot material (up to a few tens of degrees centigrade). No incandescent material was visible in the footage of the visible-light camera at the Montagnola (EMOV).
STROMBOLI
Stromboli volcano is in a state of persistent eruptive activity, normally with explosions of medium to low intensity occurring from a number of vents located within the summit crater. During the month of March 2011, the activity continued at fluctuating levels, without, however, culminating in any major events. The activity was concentrated at two active vent areas, in the northern and southern sectors of the crater terrace.
The most active vent was N1, at the northern rim of the crater terrace, which produced jets of coarse-grained material (lapilli and bombs) sometimes mixed with ash, of medium to high intensity (sometimes the jets rose higher than 200 m above the crater terrace). The nearby vent N2 showed occasional low intensity explosions launching coarse-grained material, which alternated with mild spattering activity that increased in vigor on 8 and 14 March. The average interval between explosions varied from 3 to 4 events per hour.
In the southern portion of the crater terrace, two vents (S1 and S2) were active early in the month; subsequently only the more southerly (S1) remained active, producing jets up to 120 m high. The mean frequency of the explosions varied from 1 to 10 events per hour. On 2-3 March, weak spattering was observed at S1, which showed several temporary increases in intensity.
VULCANO
Vulcano is currently in a state of quiescence. During the month of March 2011, temperatures measured in fumaroles on the crater rim remained stable. No anomalies were observed in the geochemical parameters of the peripheral areas (soils in the Vulcano Porto areas and thermal aquifers).