Séminaire ISTerre

Mapping the mantle transition zone discontinuities using body waves from noise correlations / Towards understanding the influence of environmental effects on daily seismic velocity changes

jeudi 30 novembre 2023 - 11h00
Yang Lu and Richard Kramer - Department of Meteorology and Geophysics, University of Vienna, Universitätsring, Austria
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Topic 1: by Yang Lu, Mapping the mantle transition zone discontinuities using body waves from noise correlations Recent studies have demonstrated the feasibility of recovering body waves from noise correlations, opening up new prospects for imaging the deep Earth. In this talk, I will highlight a successful application for mapping the mantle transition zone topography beneath the greater Alpine region. By analyzing the short-period (4-10 s) P-wave reflections retrieved from noise correlations, we reveal clear lateral depth variations of the 410km and 660km discontinuities, shedding light on the complex mantle transition zone configuration. This provides new important constraints on present and past mantle dynamics in the region, and it shows the strong potential of passive seismic imaging for studying deep-Earth discontinuities in general. Topic 2: by Richard Kramer, Towards understanding the influence of environmental effects on daily seismic velocity changes Detecting time-varying environmental processes like temperature, precipitation, or atmospheric pressure become of higher interest in seismological monitoring in recent years. A special focus is set on the periodic effects because they lead to a routine change in the seismic velocities. These velocities serve as vital indicators, connecting rock properties to the intricate interplay of strain and stress in Earth's crust, offering a direct window into tectonic activity. However, untangling these seismic signals from environmental 'noise' demands a high level of understanding of these processes and their driving forces. Beside their consideration as an unwanted overprint of the tectonic signal these velocity changes contain vital information about the subsurface and its processes.

Equipe organisatrice : Ondes et structures

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères