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The mapping of the damage caused by natural disasters is a crucial step in deciding on the actions to take at the international, national, and local levels. The large variety of representations that we have observed leads to problems of transfer and variations in analysis. In this article, we propose a representation, Regular Dot map (RD), and we compare it to 4 others routinely used to visualise post-disaster damage. Our comparison is based on a user study in which a set of participants carried out various tasks on multiple datasets using the various visualisations. We then analysed the behaviour during the experiment using three approaches: (1) quantitative analysis of user answers according to the reality on the ground, (2) quantitative analysis of user preferences in terms of perceived effectiveness and appearance, and (3) qualitative analysis of the data collected using an eye tracker. The results of this study lead us to believe that RD is the best compromise in terms of effectiveness among the various representations studied. [ABSTRACT FROM AUTHOR]

The massive production of spatialized information following the passage of an extreme natural event brings new perspectives in their post-disaster analysis. Such data collected or produced during scientific retour d’expérience allows us to dynamically explore the cause-and-effect relationships between the hazard and the territorial consequences in both spatio-temporal and multi-scale dimensions. Mapping is questioned as a shared analysis tool conducive to interdisciplinary actions and as a useful knowledge support for their transfer to populations and risk management actors, during and after experience feedback. [ABSTRACT FROM AUTHOR]

In post-disaster context, air assets represent an effective solution to act quickly in a devastated environment. Among these means, the flexibility, the economic advantage and the possibilities offered by Unmanned Aircraft System, also known as UAS, particularly in terms of 3D reconstructions and cartography, make them an alternative investigation tool that is rapidly expanding. Five applications of these UAV surveys are illustrated in this article after the passage of Hurricane Irma over the French North West Indies in September 2017 (Saint-Martin and Saint-Barthélemy). They illustrate the technical and scientific potentialities of these new tools, the modalities of their implementation, and give us also the opportunity to discuss about their limitations in the context of post-disaster feedback. The results obtained are multiple and offer a high operational value for the prevention of cyclonic risks. They concern the spatial analysis of debris dispersal and the reconstruction of associated volumes, the reliability of damage estimates on buildings, the monitoring of the reconstruction process, and the understanding of geomorphological impacts on the coastline. [ABSTRACT FROM AUTHOR]

Since June 2022, France is equipped with cell broadcast technology which alerts individuals within a predefined area. Despite the proven effectiveness of this technology, few studies take a spatial view of cell broadcast alert at a local level. Trials carried out in France were assessed only on their technical success, without verifying the rate of reception of the message by individuals in the official alert area, or the gap between the official alert area and the actual broadcast area. This study focuses on a trial conducted in April 2023 in Cannes (France). Using a geo-located survey method and spatial analysis tools, we show how cell broadcasting is more imprecise than one might think at the local level. Reception rates depend on the telephone operators and a large and ragged edge effect is measured, which means that the message is broadcast far beyond the area defined by the authorities. A second approach was to check the reception of three cell broadcast messages sent within a 20-min interval at fixed points, which revealed the fluctuation of the broadcast area over time, making its spatial extent complex to predict. Similar works should be carried out in other urban and rural areas. • Spatial data of cell broadcast notification reception are analysed in an urban context. • 41.8% of individuals did not receive notification within the official alert area. • Probability of reception depends on the operator, not the type of phone. • A significant edge effect is observed, well beyond the official alert zone. • The edge effect is spatially and timely variable. [ABSTRACT FROM AUTHOR]