The shallow magma chamber of Stromboli Volcano (Italy)

Abstract

AbstractIn this work, we integrate artificial and natural seismic sources data to obtain high‐resolution images of the shallow inner structure of Stromboli Volcano. Overall, we used a total of 21,953 P readings from an active seismic experiment and an additional 2731 P and 992 S readings deriving from 269 local events. The well‐defined Vp, Vs, and Vp/Vs tomograms have highlighted the following: (i) the region where magma cumulates at shallow depths (2–4 km below sea level (bsl)), forming an elongated NE‐SW high‐velocity body (Vp ≥ 6.0 km/s and Vs ≥ 3.5 km/s), with a very fast velocity core (6.5 ≤ Vp < 7.0 km/s) of ~2 km3; (ii) the presence of some near‐vertical pipe‐like structures, characterized by relatively high P velocities values, mainly linked to past activity (e.g., Strombolicchio); and (iii) a near‐vertical pipe‐like volume with high Vp/Vs (1.78 ÷ 1.85), located beneath to the craters (down to ~1.0 km bsl), overlying a deeper region (1.0 to 3.0 km bsl) with low Vp/Vs (1.64 ÷ 1.69), interpreted as the actual and preferential pathway of magma toward the surface. Our results demonstrate the importance of combining passive and active seismic data to improve, in a tomographic inversion, the resolution of the volcanic structures and to discover where magma may be stored.