Is there a shallow body of lower crust under the Vulsinian Volcanic Complex?

We interpreted three reversed seismic refraction profiles and three related fans in the Monti Vulsini Volcanic complex, using travel-times and amplitudes calculated with the asymptotic ray theory. The results have been compared with a 3-D velocity model calculated by means of inversion of travel-time residuals using data from explosions and from local earthquakes. The three layer seismic model of the studied area is characterized by relatively high P-velocities, generally ranging from 4.0-4.5 km/s in the uppermost layer to 6.7-7.1 km/s at a depth of about 7 km in the deepest layer. The deepest layer has very high velocity values characteristic of high-grade metamorphic rocks, such as some schists and granulites, or of some intrusive rocks such as gabbros. In the central part of the volcanic complex, lateral decreases in velocity values in the deep body have been observed from fan profiles from the related branches of three unreversed seismic refraction profiles and from 3-D inversion. This velocity anomaly could correspond to the high temperature related to the volcanic centers. The high velocity body may be connected to the shallow (5 km depth) magmatic body found 30 km north of the area and could represent a piece of lower crust. -from Authors