GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 2.2 GNGTS 2023 Spatial Analysis of Predisposing Factors for Topographic Seismic Amplification Effects P. L. Fantozzi 1 , E. Paolucci 2 , P. Pieruccini 3 , D. Albarello 1,2 1 Dipartimento di Scienze Fisiche, della Terra e dell'Ambiente, Università degli Studi di Siena, Siena, Italy 2 Consiglio Nazionale delle Ricerche, Istituto di Geologia Ambientale e Geoingegneria, Rome, Italy 3 Dipartimento di Scienze della Terra, Università degli Studi di Torino, Torino, Italy It is widely accepted that topographic irregularities may affect seismic ground motion due to focusing/defocusing of seismic waves, diffraction of body and surface waves and seismic resonance of topographic features (Bard and Riepl-Thomas, 1999; Massa et al., 2014). Extensive literature exists about observed amplification/deamplification effects documented at several sites, which reveal the complexity of the seismic wavefield in the presence of landforms such as escarpments and ridges, also due to coexistence of 1D/2D effects induced by the local seismo stratigraphical configuration.To overcome these difficulties, proxies have been proposed to provide a preliminary quantification of topographical effects. This is achieved by performing extensive parametric analyses relative to simplified 2D topographical configurations (e.g., Nguyen and Gatmiri, 2007). The considered simplified models are assumed to approximate configurations observed in the field and used to provide proxies for practical applications by avoiding complex numerical modelling. Moreover, these proxies may be of help when regional scale studies are of concern, to identify areas where significant morphological effects are expected, and more detailed studies are mandatory for a correct evaluation of local seismic response. Some of these proxies have been included in most recent seismic codes (Eurocode 8,EN 1998-1, 2004; NTC18, Ministero delle Infrastrutture e dei Trasporti, 2018) and in the Italian Seismic Microzonation Guidelines - SMG08 (SMG08, 2008). However, the identification of these reference topographic configurations is not an easy task when actual morphologies are examined, and this may produce controversial outcomes.To overcome this difficulty and check the actual feasibility of the approaches provided by the codes, a search tool has been developed in the frame of the SERENA Prin project, to find the reference topographical configurations by amorphometric analysis, based on a GIS and spatial analysis approach. The tool relies on the automatic creation of numerous morphological sections that allow identifying the