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Imagerie lithosphérique par inversion de formes d’ondes télésismiques – Application aux Alpes Occidentales

Abstract : In this thesis, a full-waveform inversion (FWI) algorithm is developed with the aim to image the elastic properties (Vp, Vs and density) of 3D lithospheric models from teleseismic recordings with a spatial resolution of the order of the wavelength. Seismic modeling is performed with a wavefield injection hybrid approach. A first simulation is performed in a global radially symmetric Earth with the AxiSEM code to compute the wavefields on the borders of the lithospheric target. Then, these wavefields are propagated in the target with the spectral finite-element method. After linearization, the inverse problem is solved with a quasi-Newton (1-BFGS) optimization algorithm. The sensitivity of the teleseismic FWI to the experimental setup (subsurface parameterization, initial model, sampling and geometry of the station layout) is first assessed with a realistic synthetic model of the Western Alps. The method is finally applied to nine events of the CIFALPS experiment carried out in the Western Alps, up to a frequency of 0.2Hz. Reliable models of P and S wave speeds and density reveal with an unprecedented resolution the crustal and lithospheric structures of the Alpine Belt, in particular the geometry of the Ivrea body, and the European and Adriatic Mohos. Deeper, two slow velocity anomalies beneath the Western Alps are imaged in the mantle. The first, to the west of the chain, is interpreted as the signature of an asthenospheric upwelling, the second near the location of the Ivrea body indicates the European slab break-off. The study supports the hypothesis of the European continental crust subduction and confirms the possible tearing of the European slab.
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Submitted on : Tuesday, October 24, 2017 - 12:35:10 PM
Last modification on : Saturday, June 25, 2022 - 11:27:51 PM
Long-term archiving on: : Thursday, January 25, 2018 - 1:06:57 PM


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  • HAL Id : tel-01622335, version 1



Stephen Beller. Imagerie lithosphérique par inversion de formes d’ondes télésismiques – Application aux Alpes Occidentales. Sciences de la Terre. Université Côte d'Azur, 2017. Français. ⟨NNT : 2017AZUR4007⟩. ⟨tel-01622335⟩



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