P‐wave arrival time inversion by using the τ‐p method: Application to the Mt. Vesuvius Volcano, southern Italy

Abstract

In this paper we have applied a τ‐p inversion method based on a non linear approach to a set of first P‐arrival times from a 2‐D active seismic experiment performed at Mt. Vesuvius in 1994. The initial seismic investigation is devoted to the study of the shallow structure and the τ‐p method has been used for modelling velocity variations of a spherically concentric medium which is a better approximation than a flat layer of the Vesuvius geometry. We are able to obtain detailed 1‐D velocity models along different specified sections of the recorded seismic, line. These sections span different depth ranges and indicate strong lateral and vertical P‐velocity variations in the first 1 km of the volcano structure with values ranging from about 1.5 km/s at the surface to 3.5–4.0 km/s at depth. The average 1‐D concentric model obtained in this study can be used as a reasonable starting model for iterative high‐resolution tomographies of Vesuvius velocity structures.