Next-GenHazards - Next-Generation Multi-Hazard Maps Accounting for Non-Ergodic Site Effects

The world population is growing at an unprecedented rate and more than 50% of the global population currently lives in urban areas. Such growing urban communities are heavily reliant on distributed infrastructure such as electric power, levee, natural gas pipeline, and transportation systems. Thus, such lifelines are vital for the resilience of surrounding communities. This rapid urban population growth produced a steep increase in the global risk due to natural disasters. This is evident comparing the estimated total damage due to natural disasters in the period 1976-1985 and that in the period 2005-2014. In only 30 years the total damage increased by an order of magnitude going from B to 0B. This value will certainly increase over time as infrastructural systems serving these communities are ageing. Among them, river- and coastal-protection levee systems and buried natural gas pipeline networks have been proven to be highly vulnerable to earthquake events and/or to earthquake-flooding cascading events. This is even more so if considering the impact of climate change. As a result, there is an urgent need to develop a consistent quantitative framework to properly analyse the risk to which these systems are exposed and define proper communication strategies with decision makers and stakeholders. The long-term goal of this research is to define strategies to make distributed infrastructure systems more resilient to future natural disasters including the effects of cascading earthquake-flooding events. The overall objective of the Next-GenHazards project is to develop the next-generation of multi-hazard maps combining data from existing seismic networks, newly-established vertical ground motion arrays, and robust geotechnical numerical models. Such maps will be developed to assess hazards from cascading earthquake-flooding events. The earthquake component will be developed removing the so-called ergodic assumption (i.e. the average earthquake source, path, and site effects from global datasets are applied as is for a site of interest – such assumption does not allow to model the actual nuances of soil behaviour at a site) from probabilistic seismic hazard analysis, PSHA, to capture site-specific ground-response features (i.e., how much each site modifies the earthquake motion). The flooding component will be analysed as a cascading event following the earthquake, with an appropriate return period that will account for climate change scenarios. These multi-hazard maps, reliant upon a novel non-ergodic probabilistic seismic hazard analysis will ultimately identify realistic scenario events for cascading hazards to which distributed infrastructure may be subjected. Unlike currently-used methods, outcomes from this projects can be used in formal risk calculations. We believe that this transformative approach has global relevance and will advance the scientific field of natural hazards engineering.