Seismic Tomography Experiment at Italy's Stromboli Volcano

Stromboli island, located in the southern Tyrrhenian sea, is the emerged part (about 900 meters above sea level) of an approximately 3 kilometer-high stratovolcano. Its persistent Strombolian activity, documented for more than 2000 years, is sometimes interrupted by lava effusions or major explosions. Despite the number of recently published geophysical studies aimed at clarifying the volcano's eruption dynamics, the spatial extent and geometrical characteristics of its plumbing system remain poorly understood. In fact, knowledge of the inner structure and the zones of magma storage is limited to the upper few hundred meters of the volcanic edifice (Chouet et al., 2003; Mattia et al., 2004) and P and S wave velocity models are available only in restricted areas (Petrosino et al., 2002). Over the past few years, Stromboli has experienced an increase in its activity, which started with the eruptive crisis of December 2002 to July 2003. The observed variations in Stromboli's eruptive behavior and the occurrence in December 2002 of a tsunami and in April 2003 of a paroxysmal vulcanian-type event with strong explosions and lava flows (Bonaccorso et al., 2003), have focused attention on the need to determine more suitable internal structure and velocity models of the volcano. To meet this need, a seismic tomography experiment through active seismics using air gun sources was done. A preliminary two-dimensional (2-D) tomographic study is presented here.