Among the characteristics of the areas in which the tsunami hazard is high, in addition to the nature of these various factors, consider the period of recurrence of these events (from a few decades to several centuries), the time limit (A delay is, according to the Wiktionary, “a time allowed to do a …) arrival of the waves (few minutes (Primary form of a document: Law: one minute is the original of a …) at several hours) and the nature of the coastal area (protected from tsunamis by naturally protective sites such as the barrier Reef (A coral reef is a bio-built structure of which corals are essentially …) and mangroves or on the contrary strongly anthropized). These aspects strongly influence the response to be provided to communities to anticipate the tsunami threat. In Martinique (Martinique is both an overseas region and an overseas department …), most of the cities are located on the coasts. Are they particularly exposed to this danger?
Docks in the town of La Trinité where we can see that the site is easily submersible (cobblestones, buildings, sea level).
© S. Colon
Knowing the tsunami danger requires the integration of several approaches: everything (The whole understood as the whole of what exists is often interpreted as the world or …) first, there is the analysis of potential sources, which they are informed by remarks (Observation is the action of a careful following of phenomena, without the will to see them …) geological, geophysical, volcanic, seismic and hydrographic. The goal is to build realistic tsunami generation scenarios. We Research (Scientific research primarily refers to all actions undertaken with a view to …) also past tsunamis: for the most recent we can rely on the instrumental period or on the first written reports, which date back to the arrival of the first Europeans; for the oldest you can go back centuries, even millennia, thanks to tracks (TRACES (TRAde Control and Expert System) is a veterinary health network of …) left in the sediments. L’together (In set theory, a set intuitively designates a collection …) helps to better understand the recurrence periods. Finally, the modeling digital (Digital information is information …) the propagation of tsunami waves, from their generation to the coasts, allows to obtain, at a lower cost, the cartography (Cartography refers to the production and study of geographical maps. The …) danger, ranging from a regional to a local scale.
The intensity of each natural hazard is constrained by the physical variables involved: here are the induced currents, the height (Height has different meanings depending on the subject area.) waves and the extension of the area offlood (The term flood traditionally refers to the overflow of a stream that …). The concept of risk is a equation (In mathematics, an equation is an equality that relates different quantities, usually …) associating this same intensity with the vulnerability (In risk management, the vulnerability of an organization or area …) people and structures.
In Martinique, studies on the spatial variability of the danger reveal that alluvial zones mainly concern mangrove areas and some urban or occupied sites on the east coast such as: La Trinité, Le Vauclin, Sainte-Marie and Le Robert. Mangroves are plant formations characteristic of some tropical and subtropical coastal areas. They turn out to form a protective barrier against waves which effectively attenuate. Their important role has been observed where the sites have been preserved and remain unoccupied: the risk of tsunami is very low there. To thein front of (In mathematics, the opposite of a number is the number such that, when it is a …), urban sites are exposed to the danger of tsunamis. Numerical simulations show, for example, that the La Trinité site is easily submersible: the drop in the middle sea level (Sea level is the average height of the sea surface, relative to a level of …) at rest and on the dock it is very low; The floors are artificial and therefore not very dissipative of the waves; for some major seismic scenarios, waves are likely to reach the first floor of a building.
Authors and author:
– Sirel Colón, researcher of theToulouse III University (University of Toulouse-III, (username: Paul Sabatier University) …) – Paolo Sabatier (Paul Sabatier (5 November 1854 in Carcassonne, France – 14 August 1941 …) to Geosciences Environment (The environment is everything that surrounds us. They are all natural elements and …) Toulouse (GET) / OMP.
– Mansour Ioualalen, researcher (A researcher (female researcher) refers to a person whose job is to do research …) of the’University (A university is a higher education institution whose goal is the …) French Riviera to Geoazur / OCA.
– Valérie Clouard, researcher at the University of Toulouse III – Paul Sabatier at Geosciences Environnement Toulouse (GET) / OMP.
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