An image of Mt. Vesuvius obtained by 2D seismic tomography

A high-resolution seismic tomography of Mt.Vesuvius was started in May 1994, with the aim of reconstructing the detailed shallow crustal structure underneath the volcano and define its feeding system. The first phase of the experiment was to perform a 2D profile, using three underground explosions as active sources. Data from controlled sources and microearthquakes were jointly used to determine the shallow structure of the volcano. A high-velocity body (Vp = 3.5-4 km/s) was identified at about 2 km beneath the Somna-Caldera. It is likely to represent a sub-volcanic structure, formed by a dense network of solidified dikes. A prominent converted P-to-S phase at about 10 km of depth indicates the occurrence of a sharp transition to a very low-velocity zone. This may represent the top of an extended magmatic reservoir. (C) 1998 Elsevier Science B.V. All rights reserved.