A Novel Quantitative Approach for Multi-hazard Risk Assessment of Linear Infrastructure: a Geological-Geotechnical Index

This study introduces a novel quantitative approach formulti-hazard risk assessment of linear infrastructure by introducing the GEological-geoTechnical Index (GETI). GETI aims to address the limitations of existing methodologies by incorporating the cascading effects of multiple hazards and providing a comprehensive quantitative assessment tool for stakeholders. This study highlights the challenges in maintaining linear infrastructure, such as bridges and viaducts, and the necessity for standardized procedures to assess their exposure to natural hazards. Current approaches often fail to account for the interconnected nature ofmultiple hazards, potentially leading to underestimation of risks. The GETI is conceptualized as a two-level analysis process. Level 1 involves assessing hazard susceptibility through a literature review and preliminary surveys, whereas Level 2 encompasses advanced analyses using geological and geotechnical data. The index primarily addresses seismic risk and its secondary effects, including ground motion amplification, soil liquefaction, and landslides/rockfalls. Thismethodology employs conditional probability to express the concept of the “cascade effect” in mathematical terms. The GETI is formulated as the probability of damage given the occurrence of an earthquake, considering various magnitudes of damage, fromlowto severe. This approach allows for a more nuanced understanding of risk compared to qualitative or semiquantitative indices. This study acknowledges the potential limitations of the GETI, including its dependence on data availability and accuracy, as well as its current focus on seismic hazards. Future research directions are proposed, such as expanding the index to include a broader spectrum of natural hazards and extending its applicability to other types of linear infrastructure. The GETI represents a significant advancement in multi-hazard risk assessment for linear infrastructure. By providing a quantitative measure that accounts for the interrelated nature of natural hazards, it offers stakeholders a valuable tool for prioritizing risk-reduction measures and ensuring the safety and resilience of critical infrastructure. The practical application of GETI in a case study in Italy is finally presented to verify its real-world functionality and effectiveness in infrastructure management.