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Seismic microzoning in the metropolitan area of Port - au-Prince - complexity of the subsoil

Abstract : The magnitude 7.3 earthquake that struck Haiti in January 12, 2010 has caused a lot of damages in surrounding areas epicenter. These damages are due to a lack of knowledge of the Haitian subsoil. To overcome this problem, the LNBTP, the BME and BRGM have agreed to implement a project of seismic microzonation of the metropolitan area of Port-au-Prince which is financed by the Fund for the reconstruction of the country. The seismic microzonation is an important tool for knowledge of seismic risk. It is based on a collection of geological, geotechnical, geophysical and measures and recognition and the campaign of numerous sites. It describes a class of specific soils with associated spectral response. The objective of the microzoning is to identify and map the homogeneous zones of lithology, topography, liquefaction and ground movements. The zoning of lithological sites effect is to identify and map areas with geological and geomechanical consistent and homogeneous seismic response; the objective is to provide, in each area, seismic movements adapted to the ground. This zoning is done in about five steps: 1- Cross-analysis of geological, geotechnical and geophysical information; 2- Such information comprise the existing data collected and the data acquired during the project; 3- Identification of homogeneous areas. 4- Definition of one or more columns of representative soils associated with each zone; 5 - Possible consolidation of area to get the final seismic zoning. 27 zones types were considered for the study of sites effects after the analysis of all geological, geotechnical and geophysical data. For example, for the formation of Delmas, there are 5 areas with soil classes ranging from D to C. Soil columns described in the metropolitan area of Port-au-Prince are processed with the CyberQuake software, which is developed at the BRGM by Modaressi et al. in 1997, to calculate their response to seismic rock solicitation. The seismic motion is determined by 4 accelerograms (2 real and 2 altered real) having a spectral response close to the spectrum of acceleration to the rock. In sum, the seismic microzoning presents a better perspective for the preparation of the plan for the prevention of seismic risk (PPRS) and for the establishment of seismic rules in the metropolitan area of Port-au-Prince.
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https://hal-brgm.archives-ouvertes.fr/hal-01059325
Contributeur : Didier Bertil <>
Soumis le : vendredi 29 août 2014 - 17:10:43
Dernière modification le : vendredi 12 juin 2020 - 16:00:03

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  • HAL Id : hal-01059325, version 1

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Ronaldine Gilles, Didier Bertil, Claude Prépetit, Myriam Belvaux, Agathe Roulle, et al.. Seismic microzoning in the metropolitan area of Port - au-Prince - complexity of the subsoil. American Geophysical Union Fall Meeting : AGU 213, Dec 2013, San Francisco, United States. pp.Abstract S51A-2312. ⟨hal-01059325⟩

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