Post-earthquake fire risk assessment of historic urban areas: a scenario-based analysis applied to the historic city centre of Leiria, Portugal

Abstract

Recent natural and anthropic disasters have aroused the interest of the scientific and governmental community in seeking more efficient and effective risk mitigation strategies. Index-based approaches have received particular attention in the field of disaster risk because of their extraordinary capacity to synthesise and spatially contextualise vulnerability. Motivated by the massive impacts of earthquakes, the seismic risk field has gained popularity over the last few decades. However, little attention has been paid so far to a potentially highly impacting phenomenon: post-earthquake fires. Historical records have shown that fire ignitions triggered by earthquakes present a significant likelihood of ending up in massively destructive urban fires whose consequences are even more dreadful than those of the earthquake itself. This paper aims to contribute to the body of knowledge in the field of post-earthquake fires by presenting a scenario-based analysis in the Historic City Centre of Leiria. Firstly, two seismic vulnerability index methodologies are applied to obtain post-earthquake damage scenarios. Then, a risk matrix is used to identify the buildings that are more prone to suffer post-earthquake fire ignitions. Finally, fire spreading and suppression conditions are examined and discussed through a detailed analysis where fire risk outputs, damages, and the accessibility conditions of the area are combined to obtain an integrated post-earthquake fire analysis. The results show that for a seismic event of intensity Iems-98 = VIII, 33% of the total surveyed buildings could present a moderate or high risk of post-earthquake fire ignition.