Design of a virtual test bed for the Italian territory: Proof of concept for multi-hazard scenarios effects in the context of a national resilience assessment

Creating quantitative tools to assess scenarios of impacts of geological processes (such as landslides, subsidence, volcanic eruptions, earthquakes), often chained in a “domino-like” effect, is an ambitious goal for quantifying risk and, consequently, supporting effective mitigation and resilience planning. The RETURN Project, funded by the Italian National Recovery and Resilience Plan (PNRR), integrated multidisciplinary expertise to generate such scenarios and demonstrate their feasibility through a Virtual Test Bed (VTB). The need to create this virtual demonstration environment arises from the complexity of the cause-effect relationship in natural processes while enabling the evaluation of influencing factors and parameters through scalable and territorially transposable approaches. To this end, RETURNLAND was designed as a digital space composed a complex mosaic of territorial elements extracted from the Italian surface and broadly representative of physiographic units and the geological processes active within them. RETURNLAND was used to activate tool chains capable of producing irreversible effects on the ground surface and in the submarine environment (within the near shore), which can be addressed, through impact chains, to damage infrastructure, urban areas, and communities. Among these chains, landslide-induced tsunami and consequent coastal flooding, ash-fall and ignimbrite flow propagation, subsidence and sinkholes related to sea level rising are here presented. RETURNLAND, with its virtual space, represents part of a larger Proof of Concept of the RETURN project which, among others, includes, with the same meaning as VTB, urban realities (defined as RETURNVILLEs) and human communities.