Earthquakes and historic masonry buildings: an experimentally based algorithm for debris formation prediction

Immediately after an earthquake, the emergency paths play an important role for evacuees and rescuers in historic centres. Especially in historical scenarios, earthquake effects could affect the mobility system and interaction between people and modified scenario. The spreading of debris from damaged buildings on the paths could obstacle the citizens’ evacuation to safe points and rescue operations. For this reason, defining quick criteria about seismic behaviours of historic building and related debris formation along streets and public spaces are the first steps in defining effective damage scenario maps, designing risk reduction interventions on critical areas, evaluating emergency plans and innovative risk-reduction tools for helping peo-ples. The present work offers an experimental relationship for the estimation of external debris for-mation (amount of debris along streets) by means of post-earthquake aerial images of Italian historic centres (images of the immediate aftermath of L’Aquila-2009 and Emilia-2012 earth-quakes are examined). For each building, the quick proposed algorithm evaluates the percent-ages of external debris area (along the facing street) as function of its vulnerability and earth-quake magnitude (Richter scale). The algorithm is firstly validated by comparing predicted and effective values of ruins area depths in the considered case-studies. Similar debris estimation relationships could offer significant information for evaluating risk levels in street network damages and could be also combined with simulations about probable pedestrians’ evacuation in post-earthquake scenario. Results will be useful in order to reduce the identified interfer-ences between built environment and evacuation process through interventions on critical his-toric buildings (in their relations with the street network elements) and strategies for emer-gency management.