Three‐dimensional modeling of Mount Vesuvius with sequential integrated inversion

Abstract

A new image of Mount Vesuvius and the surrounding area is recovered from the tomographic inversion of 693 first P wave arrivals recorded by 314 receivers deployed along five profiles which intersect the crater, and gravity data collected in 17,598 stations on land and offshore. The final three‐dimensional (3‐D) velocity model presented here is determined by interpolation of five 2‐D velocity sections obtained from sequential integrated inversion (SII) of seismic and gravity data. The inversion procedure adopts the “maximum likelihood” scheme in order to jointly optimize seismic velocities and densities. In this way we recover velocity and density models both consistent with seismic and gravity data information. The model parameterization of these 2‐D models is chosen in order to keep the diagonal elements of the seismic resolution matrix in the order of 0.2–0.8. The highest values of resolution are detected under the volcano edifice. The imaged 6‐km‐thick crustal volume underlies a 25 × 45 km2 area. The interpolation is performed by choosing the right grid for a smoothing algorithm which prepares optimum models for asymptotic ray theory methods. Hence this model can be used as a reference model for a 3‐D tomographic inversion of seismic data. The 3‐D gravity modeling is straightforward. The results of this study clearly image the continuous structure of the Mesozoic carbonate basement top and the connection of the volcano conduit structure to two shallow depressions, which in terms of hazard prevention are the regions through which magma may more easily flow toward the surface and cause possible eruptions.