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Communication dans un congrès

From Geology to Realistic Large-Scale Spectral-Element Earthquake Simulations in the Pointe-à-Pitre Region

Abstract : The goal of this study is to perform realistic large-scale spectral-element simulations in the vicinity of Pointe-à-Pitre, valid up to rather high frequencies (around 5 Hz) with a minimal shear-wave velocity around 200 m/s and considering magnitude 5 to 6 earthquakes. For this purpose, a detailed modeling of both the seismic source and geology of the medium for wave propagation and of the local urban underground is necessary. The local geology (size: 7 x 7 x 0.1 km) has been constructed using brgm Geomodeler© software, by compiling the available underground data (e.g. boring data) in the vicinity of the city of Pointe-à-Pitre. Four main geological formations are considered for the regional model: a weathered limestone (which form the substratum) and clay, silt and ballast (which form soft sedimentary basins). The shear-wave velocities within each formation have been derived from the existing geophysical campaigns (e.g. SASW, cross-hole, H/V, etc.). The S-wave velocity value of the limestone is supposed to be 1000 m/s. For the clay, silt and ballast formations, S-wave velocity values are respectively equal to 350 m/s, 250 m/s and 200 m/s. In order to mimic energy dissipation, the constitutive law of these formations is supposed to be viscoelastic. The local geology of the urban zone is included into a larger geological model (Dorel, 1978) of size 40 x 30 x 30 km. Moreover, topography is included in the model by using a 40 meters DTM. In the present simulations, the Gosier fault, located to the Southeast of Pointe-à-Pitre, has been considered. The slip distributions of the finite-fault are generated according to the spatial random field model developed by Mai and Beroza, 2002. For magnitude 5 or 6 earthquakes, the kinematic fault is composed respectively by 899 or 7881 sub-faults with a heterogeneous slip distribution. The results of these simulations are shown as PGV map on the entire domain or time history recorded at high stake facilities of Pointe-à-Pitre (e.g. city council, hospital, schools, etc.).
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Communication dans un congrès
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https://hal-brgm.archives-ouvertes.fr/hal-00581352
Contributeur : Florent de Martin <>
Soumis le : mercredi 30 mars 2011 - 17:01:30
Dernière modification le : mercredi 8 juillet 2020 - 11:10:20

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  • HAL Id : hal-00581352, version 1

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Florent de Martin, Erwan Bourdon, Gabriel Courrioux, Evelyne Foerster, Anne Lemoine, et al.. From Geology to Realistic Large-Scale Spectral-Element Earthquake Simulations in the Pointe-à-Pitre Region. 19ème Conférence géologique de la Caraïbe(19th Caribbean Geological Conference), Mar 2011, Le Gosier, Guadeloupe, France. ⟨hal-00581352⟩

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