Advances in the study of geophysical signals from Mt. Etna volcano.

Abstract

Long-period seismic signals, including LP events and tremor, observed on many volcanoes worldwide, may play a crucial role in the forecasting of volcanic eruptions as these signals are direct indicators of sub-surface magma dynamics. Their location is widely agreed to be useful for mapping the extension and geometry of the plumbing system and also for quantifying pressure transients caused by resonance or movement of fluids along the conduits. At Mt. Etna detailed investigations on these signals started systematically only after the installation of a broad-band seismic network (since 2003). Thereafter, we present the main results recently obtained on this volcano by analysing tremor, LP and VLP events during two eruptive episodes in the second half of 2007. We also discuss results of cross analysis performed between tremor and gravity sequences acquired simultaneously at Mt. Etna during the 2002-03 eruption and during the December 2005-January 2006 period of quiescence. We detected common anomalies which are indicative of a quasi-closed system, becoming progressively enriched in volatiles. These studies, carried out in the framework of the VOLUME Project, provide new insight into the shallow plumbing system of Etna and grant valuable tools for volcanic hazard forecasting and risk mitigation.