 | |
| GEOL0234-1 | Modelling and inversion in geophysics
 |
|
| Duration : | 15h Pr, 15h Th |
|
| Credits/ECTS : |
|
|
| Holder(s) : | Frédéric Nguyen |
|
| Language : | Langue française |
|
| Course contents : | How does one obtain a physical model from a finite set of noisy observations? How to assess image appraisal ? How can a 2D models represent a 3D problem? The course of "Modeling and inversion in geophysics" presents the theory and algorithms necessary to find the answers to the questions raised above. The resolution of direct and inverse problems will be exposed for linear models and non-linear theory, according to a deterministic and Bayesian approach. Particular attention will be paid to numerical, mathematical and statistical aspects in relation with geophysical applications.
Many exercices will be resolved in Matlab, where students can create their own codes and test them on actual data (eg Deep Ocean Drilling vertical seismic profiling). Several practical cases will be solved through software commonly used in geophysical prospecting companies or equivalent (eg Mag3D, Grav3D, EM1DFM, Res2dinv). |
|
| Course objective : | The course aims to cover the following aspects:
Modeling:
Fundamental geophysical equations (eg wave equation, eikonal equation, Poisson equation, Laplace equation, Maxwell's equations)
Integral representation and differential methods for geophysics
Linear and nonlinear inversion:
Method of Backus and Gilbert
Singular values decomposition
Regularization (Tikhonov, Occam, maximum entropy, total variation)
Iterative methods in ray tomography
Bayesian methods
Particular attention will be paid on the concepts of resolution, sensitivity, and covariance model. |
|
| Prerequisites : | GEOL0021-7 Geophysical Prospecting or equivalent |
|
| Workshops : | The lab work will occur at each lecture after presentation of the theory. For each lab, a report must given for the following week per team of 2 students. The labs required a laptop, Matlab, as well as different geophysical softwares which will be provided. |
|
| Organization : | The course takes place during the first quadrimester. |
|
| Written notes : | ./ |
|
| Assessment : | Lab reports: 50%, 1 grade per team
Oral exam on the reports: 50%, 1 individual grade |
|
| Contacts : | F. Nguyen f.nguyen@ulg.ac.be
Tel: 043663797 |
|
| Remarks : | Reference textbook: Parameter estimation and inverse problems. Aster R.C., Borchers B., and Thurber C.H. Elsevier Academic Press. 2005. |
|
|
| |
