Simulating to evaluate, manage and improve earthquake resilience in historical city centers: Application to an emergency simulation-based method to the historic centre of Coimbra

Earthquake resilience in historical centres is significantly affected by interactions between the built environment, defined as the network of building heritage and surrounding open spaces, and hosted population. Building vulnerability, earthquake-induced effects and population's exposure mainly influence the first emergency phases. In the immediate post-earthquake evacuation conditions, people should leave their position to gather in assembly points where first responders can rescue them. Thus, joint analyses of building damage and evacuation flows along the evacuation paths become essential to determine the risk levels for the urban scenario and to provide risk-mitigation solutions. This paper tries to reach this goal by adopting a holistic simulation-based approach. A simplified vulnerability assessment method is used to evaluate the seismic performance of masonry façade walls and to estimate debris depth on outdoor spaces. An existing earthquake pedestrians' evacuation simulator is used to evaluate the probable pedestrians' choices in such evacuation post-earthquake damage scenarios. Then, risk indexes, combining damage assessment and evacuation results, are provided to quantify evacuation safety and to outline critical conditions in the urban layout. Finally, the impact resulting from the consideration of a series of resilience-increasing strategies is simulated and discussed from the proposed risk indexes. A part of the historic centre of Coimbra, Portugal, one of the oldest and most relevant Portuguese cities, is used in this work as a pilot case study. Results show how the method could be used by Local Authorities and Civil Protection Bodies to outline, analyse and coordinate resilience-increasing strategies at the urban scale.