Integrating human behaviour and building vulnerability for the assessment and mitigation of seismic risk in historic centres: Proposal of a holistic human-centred simulation-based approach

Abstract

The complexity of historic centres implies that risk assessment in those areas should be based on joint analyses of the characteristics of the built environment and the population's features, exposure and interaction with the surrounding environment. Such a holistic approach is urgently needed to evaluate the impact of mitigation strategies, especially in sudden onset disasters, and, mainly, earthquakes. In fact, the effectiveness of retrofitting interventions and emergency management strategies on the safety level depends greatly on such interactions, also in relation to the path network features. This work proposes a PDCA-based methodology for earthquake risk assessment which innovatively combines built environment damage assessment with a simulation of human evacuation behaviour so as to identify potentially inaccessible evacuation paths and urban areas, define related paths/areas safety levels and evaluate the impact of proposed retrofitting and management strategies on the population's safety in an emergency. To this end, a validated seismic vulnerability index method for masonry façade walls is combined with empirical damage assessment correlations (debris depth estimation in outdoor spaces) to create post-earthquake damage scenarios. Then, these are used as input data for evacuation process assessment through an existing earthquake pedestrians' evacuation simulator. Paths and safe areas risk indices are proposed to evaluate the main behavioural issues in emergency conditions. Finally, different solutions aimed at improving evacuation safety (i.e. emergency plans, rescuers' access strategies and retrofitting of buildings) are proposed and discussed for a significant case study, the historic centre of Coimbra, Portugal.