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Definition of models of shear wave seismic velocities (Vs)

 
 
Research group: Nunziata C., Costanzo M.R.,  Strollo R.
 
Main active collaborations:
Department of Mathematics and geosciences, University of Trieste
 
Vs models are defined at depths ranging from tens of metres to tens of kilometres. Such models are obtained through the non-linear inversion with the Hedgehog method of the group velocity dispersion curve of the fundamental mode of Rayleigh waves, generated both naturally (earthquakes and noise) and artificially (weight drop or explosive). Group velocities of Rayleigh waves fundamental mode are obtained by a multifilter technique named Frequency Time Analysis (FTAN) based on the frequency-time analysis of a seismic signal and allows to identify and isolate the fundamental mode and the higher modes.
In recent years successful experiments of the Green's function (surface waves) extraction from noise cross-correlations between two recording stations have been performed both on a local scale (inter-station distance of tens of kilometers) in the Campanian plain and on a small scale (inter-station distance of 60-4000 m) in the urban area of Napoli. The results of this research are very important because they have demonstrated the repeatability and robustness of the cross-correlation of seismic noise signals and its powerful capability to investigate prohibitive depths in urban areas, without drilling and source.
Comparisons with methodologies based on phase velocities (SASW, f-k, MASW) and measurements in holes have allowed to establish that FTAN method provides excellent results and is particularly recommendable for measurements in highly urbanized cities because (1) it requires only one receiver on the surface, (2) does not care of the noise, and (3) the VS models are in excellent agreement with cross-hole and down-hole measurements.
Main results of the research:
1) Seismo-stratigraphies of the urban area of Napoli;
2) A method of evaluation of the liquefaction hazard;
3) Reconstruction of the crust and upper mantle structures below the volcanic areas of Campi Flegrei, Ischia, Mt. Vesuvius and Roccamonfina, the Neapolitan area and the Campanian Plain.
 
 

Example of VS models in the urban area of Napoli (e) obtained by the non-linear inversion (Hedgehog method) of group velocities of fundamental mode Rayleigh waves (d) extracted by the FTAN method (c) from the cross-correlation functions (b) computed between pair of receivers (red line in a).
 
VSmodels below the Campanian Plain compared with the geological sections 8-9 (modified after Mostardini and Merlini, 1986) at the crossing points (1-2-3) with the investigated paths (modified after Costanzo and Nunziata, 2014). An agreement is found up to depths of ~ 8 km, but the layer with VS=3.85 km/s can be attributed to metamorphic rocks, not to Lagonegro basin sedimentary rocks.
 
Selected papers
 
Costanzo M.R., Nunziata C., Strollo R., 2017. VS of the uppermost crust structure of the Campi Flegrei caldera (southern Italy) from ambient noise Rayleigh wave analysis. DOI:https://doi.org/10.1016/j.jvolgeores.2017.09.020
Costanzo M.R., Nunziata C., 2017. Inferences on the lithospheric structure of Campi Flegrei District (southern Italy) from seismic noise cross-correlation. Physics of the Earth and Planetary Interiors, vol. 265, p. 92-105. DOI:http://dx.doi.org/10.1016/j.pepi.2017.02.010.
Costanzo M.R., Mandara R., Strollo R., Nunziata C., Vaccari F., Panza G.F., 2016. VS measurements in volcanic urban areas from ambient noise Rayleigh waves. In: Volcanic Rocks and Soils. Edited by Rotonda et. al.. p. 211-218, CRC Press/Balkema, ISBN: 978-1-138-02886-9. DOI: https://doi.org/10.1201/b18897-27.
Costanzo M.R., Nunziata C., 2016. VS models from noise cross-correlation in the historical centre of Napoli. In: Accademia Nazionale dei lincei. Resilienza delle città d’arte ai terremoti. vol. 306, p. 399-412, Roma: Bardi edizione. ISSN: 0391-805X, ISBN: 978-88-218-1141-8.
Strollo R., Nunziata C., Iannotta A., Iannotta D., 2015. The uppermost crust structure of Ischia (southern Italy) from ambient noise Rayleigh waves, Journal of Volcanology and Geothermal Research, 297, 39-51.
Costanzo M.R., Nunziata C., 2014. Lithospheric VS models in the Campanian Plain (Italy) by integrating Rayleigh wave dispersion data from noise cross-correlation functions and earthquake recordings, Physics of the Earth and Planetary Interiors, 234, 46-59.
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, DOI: 10.5772/52727
Nunziata C., Costanzo M.R., 2012. VS of shallow crust structure and site effects at L’Aquila (Italy) for the Mw 6.3, 2009 earthquake. Proceedings of the 15th World Conference on Earthquake Engineering, Lisbona. Paper No. 4134, 10 pp.
Nunziata C., De Nisco G., Costanzo M. R., 2012. Active and passive experiments for S-wave velocity measurements in urban areas.Earthquake Research and Analysis - New frontiers in Seismology, D’Amico S. (Ed), Intech Publisher (www.intechopen.com), ISBN 978-953-307-840-3,cap. 6,177-194.
Nunziata C., Gerecitano F., 2012. VS crustal models of the Roccamonfina volcano and relationships with Neapolitan volcanoes (southern Italy). International Journal of Earth Sciences, Vol. 101, Issue 5, 1371-1383,DOI 10.1007/s00531-011-0722-7.
De Nisco G., Nunziata C., 2011. Vs profiles from noise cross correlation at local and small scale. Pure and Applied Geophysics, 168, 509-520, DOI 10.1007/s00024-010-0119-8.
Nunziata, C., Costanzo M.R., 2010. Low Vs crustal zones in the Campanian Plain (Southern Italy). Mineralogy and Petrology, 100, 215-225, DOI 10.1007/s00710-010-0129-3.
Nunziata C., De Nisco G., Costanzo M.R., Vaccari F., Panza G. F., 2010. Measurements of shear wave velocities for seismic and volcanic hazard assessment in urban areas. Urban Habitat Constructions under Catastrophic Events (Proceedings), Mazzolani (Ed), Taylor and Francis Group, London, ISBN 978-0-415-60685-1, 163-168
Nunziata, C., 2010. Low shear-velocity zone in the Neapolitan-area crust between the Campi Flegrei and Vesuvio volcanic areas. Terra Nova, 22, 208–217, DOI 10.1111/j.1365-3121.2010.00936.x
Nunziata C., De Nisco G., Panza G.F., 2009. S-waves profiles from noise cross correlation at small scale. Eng. Geol., 105, 161-170.
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, pp. 370-377.
De Nisco G., Nunziata C., Vaccari F. and Panza G.F., 2008. Shear wave velocities from noise correlation at local scale. 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, pp. 354-361.
Natale M., Nunziata C., De Nisco G., Di Martino M., Panza G. F., 2006. Rayleigh group velocity (FTAN method) for detailed Vs in urban areas. 8th U.S. National Conference on Earthquake Engineering, San Francisco. Paper No. 822.
Guidarelli, M., Zille, A., Saraò, A., Natale, M., Nunziata, C., and Panza, G.F. , 2006. Shear-wave velocity models and seismic sources in Campanian volcanic areas: Vesuvio and Campi Flegrei. VESUVIUS 2000: Education, Security and Prosperity. Editor Flavio Dobran, Elsevier (ISBN-13: 978-0-444-52104-0; ISBN-10: 0-444-52104-6), 287-309.
Nunziata C., Natale M., Luongo G., and Panza, G.F., 2006. Magma reservoir at Mt. Vesuvius: size of the hot, partially molten, crust material detected deeper than 8 km. Earth and Planetary Science Letters, 242, 51-57.
Nunziata C., 2005. FTAN method for detailed shallow VS profiles. Geologia Tecnica e ambientale (Journal of technical and environmental geology), n.3, 51-69.
Natale M., Nunziata C., Panza G.F., 2005. Average shear wave velocity models of the crustal structure at Mt. Vesuvius. Physics of the Earth and Planetary Interiors, 152, 7-21.
Nunziata C., Natale M., and G.F. Panza, 2004. Seismic characterization of neapolitan soils. Pure and Applied Geophysics, 161, n°5/6, 1285-1300.
Natale M.,Nunziata C., Panza G. F., 2004. FTAN method for the detailed definition of Vs in urban areas. 13th World Conference on Earthquake Engineering, Vancouver, B.C., Canada, pp. 11.