How people react to a major disaster ?

International audienceOne of the major challenges in the field of the safety and security of populations is to reduce the number of victims and to improve people reaction to a disaster. Populations often don’t know how they should react to protect themselves to a threat.The Com2SiCa research program aims to better understand the diversity of real behaviour, rational or irrational, of the population during the crisis (including earthquake, submersion, tsunami, human made disasters such as terrorist attack...). It brings together private and public actors as geographers, psychologists, mathematicians, computer scientists and geophysicists in order to analyze individual and collective behaviour from the observation to the simulation.In this paper, we present an original database, under construction, on behaviours adopted by the population at the very time of the crisis. This database relies on a large panel of videos of the major events of the past 40 years. It is completed by operational actors’ interviews. It allows to describe the panel of human reactions that may occur during any kind of catastrophic events (natural, technological, societal). The objective is to highlight its recurrences and specificities with a set of descriptors facilitating analyses and qualitative and quantitative comparisons. These analyses also rely on a typology published in 2015. This typology is structured along two axes : 1) the level of stress 2) the temporal phases of the disaster.Based on these analyses, we propose the RPC mathematical model (for Reflex-Panic-Controlled behaviour) in order to understand these individual and collective responses as behavioural sequences. And also to study their spatial propagation. The great difficulty of carrying out in vivo experiments justifies this modelling approach. The goal is to study a wide variety of scenarios to identify critical situations. The aim is also to offer a large panel of observed situations for crisis managers’ education and training