Roccamonfina volcano (Roman Magmatic Province) sits at the margin of the NE-trending Garigliano graben. The most important episodes in the volcano's history (630-50 ka BP) have been controlled by tectonic activity associated with the graben's masterfaults. Roccamonfina volcano comprises two main parts: a stratovolcano developed inside the graben, and a complex of centres developed on the south-eastern horst. The summit of the stratovolcano is truncated by a horse-shoe shaped caldera (dimensions 6.5 km by 5.5 km) with the longest axis trending NW. The caldera opens towards the SE along NE-trending faults, which belong to the same system as the graben faults. Stratigraphical evidence indicates that caldera collapse was not caused by explosive eruptive events emplacing ignimbrites, or by sector collapse preceding ignimbrite eruptions. Geomorphological and structural observations, together with geophysical evidence, suggest that collapse of the volcano summit occurred as a mechanical re-adjustment to the high rate of the Garigliano graben extension during a climax of the regional tectonism at around 400 ka BP. The present elliptical shape of the collapsed area is due to the superposition of a linear NE-trending graben structure in the east, and a sector collapse in the west.
