Natural disasters have regularly been in the news in France. These extreme weather events call into question the entire chain of natural hazard management because they are regarded as resulting from a meteorological phenomenon of extraordinary magnitude, but also especially serious malfunctions in the protection of populations against natural elements, especially during the alert. This key moment, which determines much of the event, remains difficult to control despite the progress made by agencies to forecast weather. Indeed, it is essentially based on individual initiatives and raises the question of accountability of managers towards unplanned actions, the latter may even exacerbate the crisis. This thesis’ objective is to study the reac...