Constraining Mantle Convection Patterns by Joint Geodynamic and Seismological Modelling

The study of the Earths interior has been traditionally based on seismological and geodynamic modelling, the first one providing important information about its present-day structure, composition and state, while the second about its dynamics and compositional evolution. Seismological and geodynamical modelling are very often conducted independently, which creates mechanical and geometrical inconsistencies across the models, hampers the interpretation of seismic observations in terms of geodynamic processes and enhances the non-uniqueness of geodynamic model predictions. An alternative approach is combining computational seismology and geodynamics with mineral physics, which provides a comprehensive understanding of the Earth's interior processes, seismic behavior, and material properties. In this multidisciplinary methodology, the geodynamic flow calculations are used to compute the rock elastic properties as a function of strain-induced mantle fabrics through micro-mechanical models of crystal aggregate deformation, and of the local P-T conditions with thermodynamically self-consistent models of mantle mineralogy. The obtained seismic mantle structure is then used for seismological synthetics, such that specific hypotheses on mantle dynamics can be tested directly against seismic data. Examples from the South American, North American, and the Central Mediterranean convergent margins will be discussed. Finally, I will introduce ECOMAN, a recently developed, open-source software package that is intended to overcome the computationally intensive nature of this approach and the lack of a dedicated and comprehensive computational framework for modelling strain-/stress-induced rock fabrics and testing the effects of the resulting mechanical (elastic and viscous) anisotropy on seismic imaging and mantle convection.