A multidisciplinary and multiscalar workflow for the systematic characterization of active and capable faults for linear infrastructure design

This PhD thesis focuses on the characterization of seismic hazard associated with the surface effects induced by moderate-to-strong earthquakes, particularly those generated by Active and Capable Faults (ACFs). The work aims to support the mitigation of seismic risk for linear infrastructures (e.g., roads, railways, pipelines) planned in tectonically active regions such as Italy. While current regulations provide guidelines for most earthquake-related phenomena, explicit requirements for assessing fault displacement hazard due to ACFs are still lacking. Moreover, official databases often lack the geological and seismological parameters needed for quantitative analyses, and existing methodologies rarely address the spatial extent of long linear infrastructures, which cannot systematically avoid fault crossings. Therefore, risk mitigation must rely on accurate fault characterization and appropriate design and construction measures to accommodate expected surface displacements. Within this framework, four representative interference scenarios between ACFs and linear infrastructures were identified, reflecting the structural complexity of fault zones. These scenarios were used to define which geological and seismological parameters should be prioritized according to the fault characteristics. A five-step operational workflow was developed for deriving deterministic inputs for Probabilistic Fault Displacement Hazard Assessment (PFDHA), supporting its integration within engineering design practices. The multiscale and multidisciplinary procedure in the workflow was supported by three geological case histories that are representative of different degrees of pre-existing knowledge, data availability, and surface exposure conditions. Then, a MATLAB-based code, FaulTED, was developed to integrate published PFDHA models and generate site-specific hazard curves and fault-specific displacement maps. It also introduces an alternative methodological framework to incorporate location uncertainty on earthquake epicenter and related surface rupture. Finally, the Annex includes my contribution to updating the SURE2.0 database. Overall, this research provides conceptual and operational advances toward incorporating ACF’s characterization and PFDHA into the design framework of linear infrastructures near active fault zones.