Ground deformation monitoring at Mt Etna; evidence for dyke emplacement and slope instability

Abstract
Ground deformation monitoring at Mount Etna has successfully enabled the sub-surface paths of two shallow feeder-dykes to be traced, and their dimensional parameters, depths and departures from the vertical, to be constrained. Determinations of horizontal movement have recorded the displacement, by 3.6 m (maximum), of a rim segment of the Valle del Bove flank caldera, due to dilation associated with dyke emplacement adjacent to the rim over the period 1981 to 1989. Small-scale collapse along this rim segment, associated with the opening of the 1989 fissure, points to increasing slope instability, and highlights the potential for major failure and debris avalanche generation.