No abstract

Terra Nova, 22, 208–217, 2010 Abstract Some Vesuvio earthquakes recorded at OV‐INGV stations in the Campi Flegrei volcanic area have been processed by FTAN (frequency–time analysis) method. The group velocities of Rayleigh‐wave fundamental mode have been extracted in the period range 0.7–3 s. Regional group and phase velocity data have been considered as well at the inversion stage. Average shear wave velocity models for the uppermost 73 km of the lithosphere below the Neapolitan area, midway between Campi Flegrei and Vesuvio volcanic areas, have been obtained by the hedgehog nonlinear inversion method. The resulting structural models are characterized by the presence of the carbonate horizon at about 3 km depth. A main feature is represented by low VS velocities around 9 km depth. This low‐velocity layer, already found below both Campi Flegrei and Vesuvio, can be reasonably interpreted as a magmatic reservoir of Campania active volcanoes.

No abstract

No abstract

The seismic ground motion of a test area in the eastern district of Naples is computed with a hybrid technique based on the mode summation and the finite difference methods. Synthetic seismograms are validated with the 1980 Irpinia earthquake, a good example of strong shaking for Naples, recorded 10km from the modeled sites. Realistic SH and P-SV wave seismograms are computed along geological cross sections representative of the area. As expected, the sedimentary cover causes an increase of the signal's amplitudes along the radial and transverse components. The spectral amplification of the vertical motion is generally negligible; instead, that of the horizontal motion ranges between 2 and 5 in the 0.7-2.2 Hz frequency range. Average and maximum spectral amplifications are considered along the different geological cross sections and acceleration response spectra for the Irpinia earthquake are evaluated in order to formulate appropriate design spectra and improvements to the building code.