### Some applications of least-squares inversion in exploration geophysics

**Plessix, R-E ***(Shell Global Solutions International)*

Wednesday 14 December 2011, 09:00-09:30

Seminar Room 1, Newton Institute

#### Abstract

In exploration geophysics, we often obtain subsurface images from the data we record at the surface of the Earth. This imaging problem can be formulated as a data misfit problem. However, we face a number of numerical challenges when we want to apply this approach with seismic or electromagnetic data. We first need to efficiently compute some approximations of the elastodynamic or electromagnetic equations. Secondly, we need to solve the inverse problem with a local optimization because of the large problem size. During this presentation, after having briefly discussed the numerical solutions of the partial differential equations governing the physics, we shall describe the inverse formulation. Then, we shall present some of the applications and the difficulties we encounter in practice.