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Section 3 of the Chapter 6 of the book "Vesuvius: Education, Security and Prosperity" is presented. It presents the results of the full moment tensor inversions performed for 28 selected earthquakes corresponding to the 1999-2000 Vesuvian seismicity episode. It compares the seismic sources at Vesuvius and Phlegraean.

Section 2 of the Chapter 6 of the book "Vesuvius: Education, Security and Prosperity" is presented. It shows the cellular dispersion relations which correspond to the Neapolitan volcanic area. It discusses the employment of the surface-wave data to retrieve through the nonlinear inversion the average structural models of the uppermost 30 kilometers.

Section 1 of the Chapter 6 of the book "Vesuvius: Education, Security and Prosperity" is presented. It provides information on the Campanian region which is characterized by the presence of different volcanic areas including the volcanoes Vesuvius and Phlegraean Fields. It describes the new structural models for Phlegraean Fields up to the depths of about 30 kilometer.

Section 4 of the Chapter 6 of the book "Vesuvius: Education, Security and Prosperity" is presented. It concludes the inverse correlation of the size of the isotropic component at Mount. Vesuvius with the depth. Moreover, it cites that the isotropic component at Phlegraean Fields is associated with the change in the seismicity rate.

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This chapter summarizes a comparative study of shear-wave velocity models and seismic sources in the Campanian volcanic areas of Vesuvius and Phlegraean Fields. These velocity models were obtained through the nonlinear inversion of surfacewave tomography data, using as a priori constraints the relevant information available in the literature. Local group velocity data were obtained by means of the frequency-time analysis for the time period between 0.3 and 2 s and were combined with the group velocity data for the time period between 10 and 35 s from the regional events located in the Italian peninsula and bordering areas and two station phase velocity data corresponding to the time period between 25 and 100 s. In order to invert Rayleigh wave dispersion curves, we applied the nonlinear inversion method called hedgehog and retrieved average models for the first 30-35km of the lithosphere, with the lower part of the upper mantle being kept fixed on the basis of existing regional models. A feature that is common to the two volcanic areas is a low shear velocity layer which is centered at the depth of about 10 km, while on the outside of the cone and along a path in the northeastern part of the Vesuvius area this layer is absent. This low velocity can be associated with the presence of partial melting and, therefore, may represent a quite diffused crustal magma reservoir which is fed by a deeper one that is regional in character and located in the uppermost mantle. The study of seismic source in terms of the moment tensor is suitable for an investigation of physical processes within a volcano; indeed, its components, double couple, compensated linear vector dipole, and volumetric, can be related to the movements of magma and fluids within the volcanic system. Although for many recent earthquake events the percentage of double couple component is high, our results also show the presence of significant non-double couple components in both volcanic areas. [ABSTRACT FROM AUTHOR]