Speaker: Juan Sebastian Osorno Bolivar
Date: Thursday 20th of July 2023, 1:15pm.
Abstract:
The restoration techniques that provide means for structural geologists to better understand the tectonic history of present-day geometries have been developed in a geomechanically consistent approach for more than 50 years. These usually involve linear elastic material properties, although the small deformation assumption does not hold in most case studies. Nonlinear elastic and plastic rheologies can model large deformations but they do not yield a time reversible scheme because of energy dissipation phenomena which cannot be recovered at geological timescales. Viscous deformations of geological layers described by Stokes equations have been shown to circumvent these obstacles. The goal of the present paper is to develop an inversion scheme for the effective viscosity of the geological materials at play, relying on the exploration of the admissible space based on an objective function related to the horizontality of the top surface. To perform the inversion, methods that have a strong performance solving ill-conditioned problems are considered: Covariance Matrix Adaptation Evolution Strategy (CMA-ES), Particle Swarm Optimization (PSO), Simulated Annealing, Random Search and Grid Search, all available in the GNIR library (Mazuyer et al., 2018). We apply the proposed approach to a synthetic 2D model of a faulted graben generated in the FAIStokes program (Schuh-Senlis et al., 2020).