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Andreas Fitchner - Seismic tomography across the scales: Towards a comprehensive seismic model of the European crust and upper mantle

Notícia | 03-10-2012

SEMINARIS DE LA FACULTAT DE GEOLOGIA I L'INSTITUT DE CIÈNCIES DE LA TERRA 'JAUME ALMERA'
hora: 12:00
lloc: Sala d'actes de l'Institut Jaume Almera



Andreas FITCHNER (Department of Earth Sciences, Utrecht University, Països Baixos)
Seismic tomography is our primary source of information on the current state and the evolution of the Earth's interior on all scales. Since its conception it has branched into a large number of varieties that have drawn the picture of a remarkably dynamic planet. Despite substantial progress, two major challenges remain: (1) Reproducible tomographies are not available for strongly scale-dependent properties such as Q and anisotropy. (2) The details of 3D structure in the crust and the mantle cannot be resolved consistently, which limits our understanding of crust-mantle interactions that shape the nature of plate tectonics.

To address these challenges, we develop and apply a full waveform inversion that incorporates seismic data on a wide range of spatio-temporal scales, thereby constraining the details of both crustal and mantle structure. Our method is based on the decomposition of multi-scale Earth models into a family of single-scale models using non-periodic homogenisation. The multi-to-single-scale decomposition is the foundation of iterative, gradient-based optimisation schemes that simultaneously invert data on all scales for one multi-scale model.

We demonstrate the applicability of our method in a full waveform inversion for Europe and western Asia, with a special focus on the Anatolian region (see figure below). Continental-scale structure is constrained by complete 30-200 s period waveforms, that reveal subtle features, such as the Armorican Massif, the Rhine Graben and the Massif Central. Anatolia is covered by waveforms with 8-200 s period, meaning that the details of both crust and mantle are resolved consistently. Our model contains numerous previously undiscovered structures, including the deep lithospheric expression of the North Anatolian Fault Zone.

Building on the current feasibility study, we will extend the multi-scale full waveform inversion in order to construct a consistent model of the complete European crust and upper mantle.


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