Effusion rate and the shape of aa lava flow-fields on Mount Etna

The maximum distance attained by lava flows on Mount Etna increases linearly with an increasing effusion rate for flows greater than 1 km long. By considering lava as a Bingham fluid, a simple model of the shape of a lava flow-field in terms of flows and conduits can be constructed. Calibration of this model using the flow distance-effusion rate relationship enables the variation of effusion rate during the eruption that produced the flow-field to be calculated. Analysis of the historical flank eruptions of Etna indicates a favored range of effusion rate from 15 to 45 m3/s.