Body wave attenuation heralds incoming eruptions at Mount Etna

Abstract

How fast and foreseeable is the magma ascent is one of the most impellent and unanswered issues of volcanology. The velocity of the magma upwelling depends on the local conditions of the volcanic conduit and rheology of the magma (Scandone et al., 2007). During magma emplacement in the shallow crust, transient variations of physical properties underneath active volcanoes are expected and in a few cases observed (Patanè et al., 2006). The predictability of such changes strongly depends on how fast this process is, compared to our ability to handle geophysical data and consistently resolve transient anomalies in the physical properties of the medium. Mt. Etna is a perfect natural laboratory to investigate such issues, due to the almost continuous magmatic activity and the high quality of seismologic and geodetic data. Here we show, for the first time, that seismic attenuation of local earthquakes strongly increases due to the emplacement of magma within the crust, forecasting an incipient eruption at Mt. Etna.