An accessibility graph-based model to optimize tsunami evacuation sites and routes in Martinique, France

M Péroche,F Leone,R Gutton

doi:10.5194/adgeo-38-1-2014

Abstract

Abstract. The risk of tsunami threatens the whole Caribbean coastline especially the Lesser Antilles. The first available models of tsunami propagation estimate that the travel time from the closest seismic sources would only take few minutes to impact the Martinique Island. Considering this threat, the most effective measure is a planned and organized evacuation of the coastal population. This requires an efficient regional warning system, estimation of the maximum expected tsunami flood height, preparation of the population to evacuate, and drawing up of local and regional emergency plans. In order to produce an efficient evacuation plan, we have to assess the number of people at risk, the potential evacuation routes, the safe areas and the available time to evacuate. However, this essential information is still lacking in the French West Indies emergency plans. This paper proposes a model of tsunami evacuation sites accessibility for Martinique directly addressed to decision makers. It is based on a population database at a local scale, the development of connected graphs of roads, the identification of potential safe areas and the velocity setting for pedestrians. Evacuation routes are calculated using the Dijkstra's algorithm which gives the shortest path between areas at risk and designated evacuation sites. The first results allow us to map the theoretical times and routes to keep the exposed population safe and to compare these results with a tsunami travel time scenario.

Highlights

The tsunami hazard threatens the whole Caribbean coastline, with a higher propensity for windward coasts directly exposed to the effects of earthquakes in the subduction zone of the Lesser Antilles
The French Geological and Mining Survey (BRGM) carried out preliminary studies in order to characterize this hazard in the Caribbean
Péroche et al.: Optimize tsunami evacuation sites and routes in Martinique, France sites? Where are the most efficient evacuation routes? How long does it take to evacuate them? To answer these essential questions, we propose in this paper an accessibility model of safety zones

Summary

Introduction

The tsunami hazard threatens the whole Caribbean coastline, with a higher propensity for windward coasts directly exposed to the effects of earthquakes in the subduction zone of the Lesser Antilles. Tsunamigenic earthquakes related to the tectonics of the back arc system are likely to occur (e.g. Saintes earthquakes and tsunami in 2004, Le Friant et al, 2008). The occurrence of this event in this particular geosystem must be considered because of the proximity of the possible sources to highly populated coastal areas. Based on several potential tsunamigenic sources and by means of numerical simulations, the BRGM determined a tsunami travel time (TTT) and maximum amplitude of water for Guadeloupe and Martinique islands (Pedreros et al, 2007; Poisson and Pedreros, 2007). Of the five seismic scenarios proposed, four could impact Martinique in less than 36 min (Fig. 1) which gives very short time to manage a massive evacuation of the population

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