Thickness and Viscosity of Etnean Lavas

Abstract

THE thickness of a lava flow depends, in general, on three factors: the viscosity of the flowing lava; the angle of slope of the surface over which the lava is flowing; the local topography, that is, whether the lava is ponded in a depression or not. The thickness is seldom recorded by volcanologists, and even more seldom used as a tool (for example, in the interpretation of old volcanoes in which, owing to subsequent folding or tilting, the present attitude of the lavas may differ from the original attitude). No systematic study appears to have been made of the thickness and its relationship to the viscosity and angle of slope, and this communication, which records the results of a brief study recently made of the lavas of the Italian volcano, Etna, is a first attempt to explore this inter-relationship.