Doctoral training on internal Earth

Les Houches, 15-26 octobre 2018

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2017 - Seismic imaging of upper mantle and plates

Wednesday 20 September 2017, by Philippe CARDIN

lectures by Yann Capdeville and Thomas Bodin

lecture 1: seismology and the wave equation introduction
Introduction to the main challenges in seismology.
The wave equation, the elastic tensor, anisotropy, strong and weak forms, some solutions, Green functions ...

lectures 2 & 3 : numerical approaches to solve the forward problem in seismology
Overview of methods used to solve the wave equation. Challenges and objectives.
Introduction to the spectral elements: the 1-D case. Limits and difficulties.
What do waves actually see about the earth? Tomographic images interpretation consequences.

Lecture 4: Non linear geophysical inverse problems. Uncertainty quantification. Introcution to Bayesian inference. examples of applications in seismic imaging

Lecture 5/practical: Monte Carlo sampling methods. Markov chain Monte Carlo algorithms.

Seminar (Stéphanie Durand): "Global tomography: Why ? How ? and What’s new?"
I will give an overview of the most recent tomographic models that exist today, explaining the differences in their construction (theory, data, parametrization, inverse method) and the consequences in the obtained model. I will then present the two tomographic models I developped, SEISGLOB1 and SEISGLOB2, and show the new mantle structures we can observe.
This will be followed by a practicalon how to do a tomographic model (using a 2D cartesian case) and in particular the students will test by themselves the effect of the choice of the parametrization and dataset on the resulting model.