Analysis of earthquake - induced strain effects in a recently urbanized alluvial valley (Rome)

Chiara Varone (a), Luca Lenti (b) & Salvatore Martino(a,c)
(a) Department of Earth Sciences , Sapienza University of Rome, Piazzale Aldo Moro, 5, 00185, Rome, Italy. E-mail: chiara.varone@uniroma1.it (b) University Paris-Est LCPC/ The French Institute of science and technology for transport, development and networks (IFSTTAR)/ Departement GERS- Champs sur Marne, France (c) Research Centre for Geological Risks – CERI, Sapienza University of Rome, Piazzale Aldo Moro, 5, 00185, Rome, Italy

This study is focused on evaluating local response and the earthquake–induced strains in a highly heterogeneous alluvial valley through numerical modelling approach. The case study is located S of Rome, in correspondence to the Fosso di Vallerano alluvial valley. A high-resolution engineering-geological model of the alluvial deposits that fill the valley was derived by field investigations. Several tens of borehole log-stratigraphies were also taken into account. Outputs of 1D and 2D numerical models were analysed in terms of maximum shear strain (MSS) and Shear Strain Concentration Index (SSCI) to highlight where shear strain concentrates in the engineering-geological model as well as role of lateral heterogeneities in the distribution of shear strain within the alluvial deposits. The here reported preliminary results show that earthquake-induced strain effects: i) can be mainly referred to 2D conditions, ii) are mainly influenced by the heterogeneity of the alluvial deposits, iii) are poorly influenced by the shape of the bedrock.

Earthquake-induced effects, Shear strains, Numerical modelling, Rome