COMPUTER-SIMULATIONS OF THE TUSCOLANO-ARTEMISIOS 2ND PYROCLASTIC FLOW UNIT (ALBAN HILLS, LATIUM, ITALY)

Computer simulations of the second pyroclastic flow unit of Tuscolano Artemisio volcanic eruption were carried out using a complex thermofluid-dynamic two-phase flow model. The granular flow model accounts for the mechanical and thermal nonequilibrium between the phases, particle collisions, and gas turbulence. The simulations involved actual topography of the volcano and a barrier placed at about twenty kilometers from the vent, several particle size classes, different vent diameters, and different gas and pyroclast velocities. The results from simulations show that smaller pyroclasts and larger mass eruption rates produce larger travel distances of pyroclastic flows. Computer simulations also predicted particle segregation from the flow at the break-in-slope of the volcano and at the base of the barrier, coignimbrite or phoenix columns above the flow, and flow reversals along the barrier slope. These results were found to be consistent with the general field characteristics of the second pyroclastic flow of Tuscolano Artemisio, including its large travel distance from the vent, and large deposit thicknesses at the break-in-slope of the volcano and at the base of the barrier. The simulations suggest the formation of fumarolic pipes and depositional surfaces along the barrier, and a mass eruption rate of about 10(9) kg/s.