SEISMIC EXPLORATION OF NUMERICAL THERMO-MECHANICAL GEODYNAMIC MODELS

Until recently, codes capable of advanced thermo-mechanical modelling have been limited to commercial applications. With the advent of the open-source software movement, powerful, collaborative, computational modelling tools such as Underworld (www.underworldproject.org) have now become accessible. Underworld presents an advanced, self-consistent, modelling solution for simulating complex rheologies in two or three dimensions (2/3D), incorporating realistic time-dependent kinematic and thermal boundary conditions, and allows calculation of variables such as pressure, temperature, stress, strain, and strain-rate from any timestep in the model evolution.

This wealth of data can then be used to model geophysical fields including gravity and magnetic, as well as to simulate the system response to seismic surveys. The open-source toolset RSF Madagascar (www.reproducibility.org) provides a solid framework for the simulation of elastic wave propagation through complex 2/3D models, as well advanced seismic data processing techniques. By coupling these two numerical codes, an exciting opportunity to explore geodynamic models via synthetic seismic probing techniques is presented.

We have developed a workflow to translate Underworld models into RSF Madagascar's native data format. Key particle and mesh data is extracted from the Underworld model output, and non-destructively interpolated into a resolution appropriate for seismic wave propagation modelling. An adaptable seismic experiment script is automatically tailored to each test case, and produces a basic seismic profile of the Underworld model.

This workflow aims to facilitate advanced ground-truthing of complex Underworld models, allowing for direct comparisons between synthetic seismic sections and real seismic data. Using these comparisons, the iterative refinement of crustal deformation models is possible, and presents a new way to constrain subsurface geology in regions of poor data in a geometrically, thermally and mechanically self-consistent way.