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Nature du bruit de fond sismique: implications pour les études des effets de site

Abstract : The H/V ambient vibration method has the potential to significantly contribute to effective seismic risk mitigation, in particular in urban areas. However, physical basis and actual relevancy for site effects estimates of this method have never reached a scientific overall agreement. Within the framework of the SESAME (Site EffetcS using AMbient Excitations) European project we investigate the nature of ambient seismic noise in order to define the reliability of the H/V technique. Through numerical and experimental approaches we will answer the following questions: what is the ambient noise? Which origin? Which nature? Which kind of waves composes the noise wavefield? Body waves or surface waves? We will point out that the answers of these questions are not univocal, the physical composition of the ambient noise wavefield, and thus the H/V peak origin, is influenced by: 1) the soil characteristic (especially the impedance contrast between sediment and bedrock); 2) the spatial localization of noise sources. One of the most important issue of this study is, whatever the H/V peak origin (Rayleigh waves ellipticity, Love waves Airy phase, or the S-wave resonance), the H/V peak frequency observed on H/V curves gives a good estimate of the fundamental resonance frequency (for a 1D sedimentary structure). On the other hand, we show the limits of this method to estimate the site amplification factor.
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https://tel.archives-ouvertes.fr/tel-00007397
Contributor : Sylvette Bonnefoy-Claudet <>
Submitted on : Monday, January 17, 2005 - 2:43:11 PM
Last modification on : Friday, September 25, 2020 - 3:13:54 AM
Long-term archiving on: : Friday, April 2, 2010 - 8:45:57 PM

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  • HAL Id : tel-00007397, version 1

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Sylvette Bonnefoy-Claudet. Nature du bruit de fond sismique: implications pour les études des effets de site. Géophysique [physics.geo-ph]. Université Joseph-Fourier - Grenoble I, 2004. Français. ⟨tel-00007397⟩

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