Analyse du bruit microsismique associé à la houle dans l'océan Indien

Abstract : Seismic data recorded on oceanic islands can be used to analyze qualitatively and quantitatively the swell through its signature in the microseismic noise. We first analysed the "secondary" noise sources, which are generated by the interaction of ocean waves with similar period within a storm, a cyclone or by the reflection phenomena off the coast. By analyzing secondary microseisms at the scale of the oceanic basin, we first performed a spatio-temporal tracking of the source, even localized thousands km off the recording seismic stations. Secondly, in the long-term, they can be used to follow the global climate change related to the ocean waves activity in a specific region. We also studied the "primary" seismic noise sources, which are created by the direct interaction of ocean waves with the coast. By analyzing these primary microseisms, we succeeded to characterize ocean waves locally in terms of amplitude, period, and, sometimes, direction of propagation. This showed that it is possible to use a seismic station as an ocean waves gauge to get precious swell data, particularly in remote and poorly instrumented areas. In the context of the Iles Éparses and of La Réunion Island, we studied a few extreme swells, which occur there frequently and can have strong social and environmental consequences. Finally, by using a temporary network of seismic stations installed in La Reunion, we studied the spatial variations of the seismic noise level across the island to characterize the swell impact on the different coasts. This study enables us to identify the most exposed spots to the swell, which may be attractive for generating renewable energy with this powerful resource yet underexploited.
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  • HAL Id : tel-01391911, version 1

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Céline Davy. Analyse du bruit microsismique associé à la houle dans l'océan Indien. Géophysique [physics.geo-ph]. Université de La Réunion, 2015. Français. ⟨tel-01391911⟩

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