The eruptive activity of the Stromboli volcano, following the major explosion of last November 1, was characterized by an increase in explosive activity. The images, recorded by the cameras placed on Pizzo above the Fossa and at an altitude of 400, made it possible to analyze the eruptive activity of the volcano and the hourly frequency of the explosions, which gradually went from low values (less than 5 events/h) until 5 November , at medium-high values (between 15 and 20 events/h) until 1 December, when a further major explosion occurred. Since then, the hourly frequency of explosions has further intensified, reaching high values (between 20 and 25 events/h) between 2 and 7 December. Following this evolution, the Civil Protection Department, having consulted the competent centers of INGV and the University of Florence, has raised the alert level of Stromboli from "Green" to "Yellow" (attention). (http://www.protezionecivile.gov.it/jcms/it/view_com.wp?contentId=COM66821)
In the following days there was a further slight increase in this activity, with an hourly frequency of explosions between 22 and 28 events/h. In the period examined, the explosive activity was mainly produced by two eruptive vents, located in the northern crater area, and by two others in the central-southern crater area. All vents are located within the depression that occupies the crater terrace.
The phenomenon is constantly monitored by the Etna Observatory, by the Vesuvius Observatory and by the Palermo Sectionof the National Institute of Geophysics and Volcanology (INGV).
Fig. 1. Images taken by the Pizzo infrared camera above the Fossa of an explosion on 9 December whose products reached the Pizzo area.
Fig. 2. Images taken by the visible camera at an altitude of 400 m showing some explosions characterized by the launch of pyroclastic material over 200 m in height.
Figs. 3 and 4. Theexplosion of 15/12/2017 seen from the two thermal cameras of Pizzo and Quota 400