Block and ash flows of Emporio (10)

These are present on the NW edge of the caldera as well as on the NW and W slopes of the volcano. These are monolithologic volcanic breccia deposited by pyroclastic flows, in turn fed by the collapse of part of the Emporio lava domes.

A minor occurrence can be identified on the southern rim of the caldera.

At some points at the foot of the formation a dacitic lava block and lapilli fallout layer in normal grading, 0.3 to 1m thick, can be observed. Numerous (7-10) flow units are subsequently observed; these consist of angular to roughly rounded blocks of andesitic lava, grain supported; their diameter ranges between 5cm to 5m with blocks of 15-20cm being the most prevalent. The fine matrix that fills the intraclast space came from friction between fragments while flowing.

Several layers exhibit several bread-crust type volcanic bombs. An ash layer is observed at the top of each flow unit; this originates from deposits of the associated pyroclastic nube. The thickness of each flow unit ranges between 1 to 5m.

Maximum total thickness of the formation is approximately 20m. Few xenoliths of older lavas are observed; these mainly appear in the lowest flow section; in some layers, inclusions of andesitic magma are in abundance.

A significant part of the formation is reworked; mud flows and debris flows prevail here.