Large Scale Joint Inversion of Geophysical Data using the Finite Element Method in escript

The program package escript is a module in python for solving mathematical modelling problems. It is based on the finite element method (FEM) and scales on compute clusters for thousands of cores. In this paper we will discuss an extension to escript for solving large-scale inversion problems, in particular the joint inversion of magnetic and gravity data. In contrast to conventional inversion programs escript avoids the assemblage of the -in general- dense sensitivity matrix which is problematic when it comes to large-scale problems. Moreover, we will show how the FEM approach can easily be used to solve the adjoined forward problems required for the gradient calculation of the cost function.