Seismic microzonations of municipalities in French West Indies
Résumé
Spatial variability of ground motion may be explained by local soil conditions; it is the so-called "site effects". Site effects are responsible for increasing duration and important amplification of strong ground motion during earthquakes and must be considered as a key parameter in local seismic hazard assessment. French West Indies are prone to strong site effects because of a particular geology, characterized by soft soil deposits and strong alteration of volcanic deposits. In this framework, and considering that French West Indies are considered as a high seismicity level zone in the French building code, part of seismic hazard mitigation policy consists in technical studies to perform identification and mapping of zones characterized by homogeneous seismic response and quantification of associated ground motion. It is the aim of seismic microzonations. In this presentation, we will expose the methodology used on the scale of municipalities for mapping homogeneous seismic areas, based on a study of geological and geotechnical conditions and some geophysical testings. Then, a study of vulnerability of buildings allows to estimate the probability of damage on various sectors for a scenario of risk corresponding to the seismic microzonation.