ABSTRACT The definition of realistic seismic input can be obtained from the computation of a wide... more ABSTRACT The definition of realistic seismic input can be obtained from the computation of a wide set of time histories, corresponding to possible seismotectonic scenarios. The propagation of the waves in the bedrock from the source to the local laterally varying structure is computed with the modal summation technique, while in the laterally heterogeneous structure the finite difference method is used. The definition of shear wave velocities within the soil cover is obtained from the non-linear inversion of the dispersion curve of group velocities of Rayleigh waves, artificially or naturally generated. Information about the possible focal mechanisms of the sources can be obtained from historical seismicity, based on earthquake catalogues and inversion of isoseismal maps. In addition, morphostructural zonation and pattern recognition of seismogenic nodes is useful to identify areas prone to strong earthquakes, based on the combined analysis of topographic, tectonic, geological maps and satellite photos. We show that the quantitative knowledge of regional geological structures and the computation of realistic ground motion can be a powerful tool for a preventive definition of the seismic hazard in Italy. Then, the formulation of reliable building codes, based on the evaluation of the main potential earthquakes, will have a great impact on the effective reduction of the seismic vulnerability of Italian urban areas, validating or improving the national building code.
Аннотация The project addressed the problem of pre-disaster orientation: hazard prediction, risk ... more Аннотация The project addressed the problem of pre-disaster orientation: hazard prediction, risk assessment, and hazard mapping, in connection with seismic activity and man-induced vibrations. The definition of realistic seismic input has been obtained from ...
... Thanks to Lapo Boschi, Christopher Bean, Claudio Chiarabba and an anonymous referee for helpf... more ... Thanks to Lapo Boschi, Christopher Bean, Claudio Chiarabba and an anonymous referee for helpful and constructive reviews. References. ... J. Geophys. Res., 99, 1355313561. CrossRef. Zollo, A., Maercklin, N., Vassallo, M., Dello Iacono, D., Virieux, J. and Gasparini, P., 2008. ...
The Sannio seismogenic area turns out to be responsible for the highest peak ground accelerations... more The Sannio seismogenic area turns out to be responsible for the highest peak ground accelerations (PGA) and seismic response spectra (SRS) at Napoli. The 1688 earthquake is considered representative of the area, and realistic synthetic seismograms have been computed for this scenario earthquake at the historical center and the eastern sector of Napoli. The use of a hybrid technique based on mode summation and finite-difference methods is fully justified by the available detailed knowledge about the geological and geophysical properties of the Neapolitan subsoil. This modeling makes it possible to recognize that amplifications of ~2 for PGA and >3 for SRS are to be expected because of the pyroclastic soil cover. Based on the information contained in the available catalogs, different magnitudes have been considered. Taking into account the correlation, valid for the Italian territory, between synthetic PGA and observed intensities, it turns out that the most probable magnitude (M) of the 1688 earthquake is 6.7, while M = 7.3 should be assigned to a conservative scenario earthquake. Comparison of the computed response spectra for the 1688 scenario earthquake with the Italian seismic building code shows that the code is adequate with respect to the expected effects at the historical center of Napoli, but that it underestimates the possible ground motion at the eastern sector, in particular at the newly developed area built after the 1980 earthquake.
ABSTRACT Shear wave velocities of the crust and upper mantle are defined beneath the Roccamonfina... more ABSTRACT Shear wave velocities of the crust and upper mantle are defined beneath the Roccamonfina volcano and surrounding Apennines (southern Italy) from the simultaneous nonlinear inversion of the local group velocity dispersion data, obtained from seismic events recorded in 1988–2004 at Roccamonfina station of the INGV-RSNC network, and regional dispersion data obtained in previous studies. The main features of the representative VS models are a carbonatic basement and a low velocity zone at 6–10 km of depth. The sedimentary succession is *5 km thick below the Roccamonfina volcano and lays above a high VS (3.8 km/s) ascribable to solidified magma body, while it is *10 km thick below the surrounding Apennines. A low velocity layer with an average thickness of 10 km is detected below the Roccamonfina volcano which can be associated with the presence of partial melting and interpreted as magmatic reservoir. Such low velocity layer, also found below the surrounding Apennines but with a reduced thickness of 2–3 km, extends to the Campanian Plain and to the Neapolitan volcanic area, from Campi Flegrei to Somma-Vesuvius.
ABSTRACT The definition of realistic seismic input can be obtained from the computation of a wide... more ABSTRACT The definition of realistic seismic input can be obtained from the computation of a wide set of time histories, corresponding to possible seismotectonic scenarios. The propagation of the waves in the bedrock from the source to the local laterally varying structure is computed with the modal summation technique, while in the laterally heterogeneous structure the finite difference method is used. The definition of shear wave velocities within the soil cover is obtained from the non-linear inversion of the dispersion curve of group velocities of Rayleigh waves, artificially or naturally generated. Information about the possible focal mechanisms of the sources can be obtained from historical seismicity, based on earthquake catalogues and inversion of isoseismal maps. In addition, morphostructural zonation and pattern recognition of seismogenic nodes is useful to identify areas prone to strong earthquakes, based on the combined analysis of topographic, tectonic, geological maps and satellite photos. We show that the quantitative knowledge of regional geological structures and the computation of realistic ground motion can be a powerful tool for a preventive definition of the seismic hazard in Italy. Then, the formulation of reliable building codes, based on the evaluation of the main potential earthquakes, will have a great impact on the effective reduction of the seismic vulnerability of Italian urban areas, validating or improving the national building code.
Аннотация The project addressed the problem of pre-disaster orientation: hazard prediction, risk ... more Аннотация The project addressed the problem of pre-disaster orientation: hazard prediction, risk assessment, and hazard mapping, in connection with seismic activity and man-induced vibrations. The definition of realistic seismic input has been obtained from ...
... Thanks to Lapo Boschi, Christopher Bean, Claudio Chiarabba and an anonymous referee for helpf... more ... Thanks to Lapo Boschi, Christopher Bean, Claudio Chiarabba and an anonymous referee for helpful and constructive reviews. References. ... J. Geophys. Res., 99, 1355313561. CrossRef. Zollo, A., Maercklin, N., Vassallo, M., Dello Iacono, D., Virieux, J. and Gasparini, P., 2008. ...
The Sannio seismogenic area turns out to be responsible for the highest peak ground accelerations... more The Sannio seismogenic area turns out to be responsible for the highest peak ground accelerations (PGA) and seismic response spectra (SRS) at Napoli. The 1688 earthquake is considered representative of the area, and realistic synthetic seismograms have been computed for this scenario earthquake at the historical center and the eastern sector of Napoli. The use of a hybrid technique based on mode summation and finite-difference methods is fully justified by the available detailed knowledge about the geological and geophysical properties of the Neapolitan subsoil. This modeling makes it possible to recognize that amplifications of ~2 for PGA and >3 for SRS are to be expected because of the pyroclastic soil cover. Based on the information contained in the available catalogs, different magnitudes have been considered. Taking into account the correlation, valid for the Italian territory, between synthetic PGA and observed intensities, it turns out that the most probable magnitude (M) of the 1688 earthquake is 6.7, while M = 7.3 should be assigned to a conservative scenario earthquake. Comparison of the computed response spectra for the 1688 scenario earthquake with the Italian seismic building code shows that the code is adequate with respect to the expected effects at the historical center of Napoli, but that it underestimates the possible ground motion at the eastern sector, in particular at the newly developed area built after the 1980 earthquake.
ABSTRACT Shear wave velocities of the crust and upper mantle are defined beneath the Roccamonfina... more ABSTRACT Shear wave velocities of the crust and upper mantle are defined beneath the Roccamonfina volcano and surrounding Apennines (southern Italy) from the simultaneous nonlinear inversion of the local group velocity dispersion data, obtained from seismic events recorded in 1988–2004 at Roccamonfina station of the INGV-RSNC network, and regional dispersion data obtained in previous studies. The main features of the representative VS models are a carbonatic basement and a low velocity zone at 6–10 km of depth. The sedimentary succession is *5 km thick below the Roccamonfina volcano and lays above a high VS (3.8 km/s) ascribable to solidified magma body, while it is *10 km thick below the surrounding Apennines. A low velocity layer with an average thickness of 10 km is detected below the Roccamonfina volcano which can be associated with the presence of partial melting and interpreted as magmatic reservoir. Such low velocity layer, also found below the surrounding Apennines but with a reduced thickness of 2–3 km, extends to the Campanian Plain and to the Neapolitan volcanic area, from Campi Flegrei to Somma-Vesuvius.
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