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Seismic microzoning

 

Partecipants:Nunziata C.  Costanzo M.R.
 
Main active collaborations:
Department of Mathematics and geosciences, Univ. Trieste
ENEA, Italian National Agency for New Technologies, Energy and Sustainable Economic Development
Dept. of Structures for Engineering and Architecture, Univ. Napoli Federico II
 
Research activity is based on the deterministic approach of the ground motion evaluation. Realistic seismograms (volume and surface waves) are computed, for scaled point or extended sources, with a hybrid technique consisting of modal summation and finite difference methods. The modal summation technique is used to compute ground motion in the 1-D layered anelastic structure. The resulting wavefield for both SH- and P-SV- waves is then used to define the boundary conditions to be applied to the 2-D anelastic region where the finite difference technique is used. Synthetic seismograms of the vertical, transverse and radial components of ground motion are computed at a predefined set of points at the surface. Spectral amplifications are computed as response spectra ratios, i.e. the response spectra computed from the signals synthesized along the laterally varying section (2-D) normalized by the response spectra computed from the corresponding signals, synthesized for the bedrock (1-D).
 
Microzoning studies were performed at Napoli, Fabriano, Nocera Umbra, Sellano, Catania, L’Aquila and Poggio Picenze.
 
Main results of the research:
 
1) Seismic microzoning of Napoli for the 1980 earthquake (MS = 6.9) in the framework of the Project UNESCO- IUGC-IGCP ‘Seismic ground motion in large urban areas’. First a detailed geological and seismic picture was set, for each quarter. Six homogeneous geological zones were recognized, for each of them, and for each Vs profile, seismograms were computed together with average and maximum response spectra and spectral amplifications, etc.
 
2) Parametric study of the ground motion variation with azimuth between Napoli and sources of the strong historical earthquakes and computation of ground motion for one of the strongest historical earthquakes, like that occurred in 1688.
 
3) Evaluation of liquefaction potential of the coastal deposits of the La Plaja beach at Catania, in the framework of the Catania project (CNR/GNDT). The liquefaction potential was estimated by assuming as input the S. Lucia earthquake (ML = 5.4) on 13/12/90, also scaled to an earthquake with M = 7.5 by assuming the empirical relationship for the italian strong earthquakes, and the scenario earthquake like that occurred in 1693.
 
4) Ground motion was modeled at L’Aquila and middle Aterno river valley for the MW 6.3, 2009 earthquake. Parametric studies of S-wave velocities of the shallowest lithotypes allowed to find a general agreement between synthetic and observed response spectra. Possible nonlinear effects were evaluated for ground accelerations greater than 0.1-0.2g, assuming the equivalent linear approach and literature data of variation of the shear modulus and damping with the deformation.
 
Maximum response spectra and PGA (g) for the radial component of the ground motion computed in the 6 zones of the urban area of Napoli for the 1980 earthquake (modified after Nunziata et al., 2008).
 
 
Comparison at the projection of the AQA station on the cross-section to AQV station of the synthetic and recorded H/V spectral ratio and response spectra (5% damping) for the 6 April 2009 (Mw 6.3) earthquake (modified after Nunziata and Costanzo, 2014)..
 
Selected papers
 
Nunziata C., Costanzo M.R., 2016. Seismic microzoning for the risk mitigation of the monuments in the historical centre of Napoli. In: Accademia Nazionale dei lincei. Resilienza delle città d’arte ai terremoti. vol. 306, p. 191-203, Roma: Bardi edizione. ISSN: 0391-805X, ISBN: 978-88-218-1141-8.
Nunziata C., Costanzo M.R., 2016. Site effects at L’Aquila for the April 6, 2009 (MW=6.3) earthquake. In: Accademia Nazionale dei lincei. Resilienza delle città d’arte ai terremoti. vol. 306, p. 413-425, Roma: Bardi edizione. ISSN: 0391-805X, ISBN: 978-88-218-1141-8.
Costanzo M.R., Nunziata C., Florio G., Formisano A., 2014. The Historical Centre of Poggio Picenze under the 2009 April 6th Earthquake: Correlation between Ground Motion and Damages to Buildings, in: F. M. Mazzolani, G. Altay (Eds), proceedings book of PROHITECH 2014 - 2nd Int. Conf. on Protection of Historical Constructions, Boğaziçi University Publishing, Istanbul (ISBN 978-975-518-361-9), 453-459.
Nunziata C., Costanzo M.R., 2014. Ground motion modeling for site effects at L'Aquila and middle Aterno river valley (central Italy) for the Mw 6.3, 2009 earthquake. Soil Dynamics and Earthquake Engineering, 61-62C, 107-123.
Costanzo M.R., Nunziata C., 2014. Ground motion modeling for the 6 April 2009 earthquake (Mw 6.3) at Poggio Picenze (central Italy). Journal of Seismology, DOI: 10.1007/s10950-014-9465-9.
Costanzo M.R., Nunziata C., Gambale V., 2013. Vs crustal models and spectral amplification effects in the L’Aquila basin (Italy). Engineering seismology, geotechnical and structural earthquake engineering, D’Amico S. (Ed), Intech Publisher (www.intechopen.com), ISBN 978-953-51-1038-5, cap. 4, 79-99.
Nunziata C., Costanzo M. R., Vaccari F. and Panza G. F., 2012. Evaluation of linear and nonlinear site effects for the MW 6.3, 2009 L’Aquila earthquake. Earthquake Research and Analysis-New frontiers in Seismology, D’Amico S. (Ed), Intech Publisher (www.intechopen.com), ISBN 978-953-307-840-3, cap. 5, 155-176.
Nunziata C., Sacco C., Panza G.F., 2011. Modeling of ground motion at Napoli for the 1688 scenario earthquake. Pure and Applied Geophysics, 168, 495-508.
Indirli M., Nunziata C., Romanelli F., Vaccari F., Panza G. F., 2009. Design and placing of an innovative 3D-Isolation system under the Herculaneum Roman Ship. Protection of Historical buildings, PROHITECH 09, Mazzolani (Ed.), Taylor and Francis Group, London, ISBN 978-0-415-55803-7, 681-687.
Nunziata C., De Nisco G. and Panza G.F., 2008. Evaluation of liquefaction potential for building code. In: Commemorating the 1908 Messina and Reggio Calabria Earthquake, Series: American Institute of Physics (AIP) conference proceedings, Springer, Vol. 1020, Santini A. and Moraci N. Editors, ISBN: 978-0-7354-0542-4, 370-377.
Nunziata C., Peresan A., Romanelli F., Vaccari F., Zoccolo E. and Panza G.F., 2008. Realistic Ground Motion Scenarios: Methodological Approach. In: Commemorating the 1908 Messina and Reggio Calabria Earthquake, Series: American Institute of Physics (AIP) conference proceedings, Springer, Vol. 1020, Santini A. and Moraci N. Editors, ISBN: 978-0-7354-0542-4, 378-385.
Nunziata, C., 2007. A physically sound way of using noise measurements in seismic microzonation, applied to the urban area of Napoli. Engineering Geology, 93, 17-30.
Nunziata C., Natale M., Imperio F., Panza G. F., 2006. Realistic ground motion scenarios for Napoli. 8th U.S. Conference on Earthquake Engineering, San Francisco, Paper No. 819.
Nunziata C., 2004. Seismic ground motion in Napoli for the 1980 Irpinia earthquake. Pure and Applied Geophysics, 161, n° 5/6, 1239-1264.
Natale M. and Nunziata C., 2004. Spectral amplification effects at Sellano, central Italy, for the 1997-98 Umbria seismic sequence. Natural Hazard, vol 33 n.3, 365-378.