© Bernhard Schuberth
Bernhard Schuberth ist Wissenschaftler an der LMU.
ECS Co-Host ist dieses Mal Valentin Bonnet Gibet.
Das DeepDyn Seminar findet online als zoom-meeting statt. DeepDyn Mitglieder erhalten den Zuganglink automatisch vor dem Seminar. Wir bitten externe Seminargäste sich für das Seminar zu registrieren, um den Zugangslink zu erhalten.
From Mantle Convection to Seismic Observations -- Simulating 3-D Wave Propagation in Geodynamic Earth Models
Illustrierte Zusammenfassung
© Bernhard Schuberth
Abstract
A profound understanding of the interaction between surface geological processes and the deep Earth requires knowledge of mantle properties in space and time. Accurate estimates of the buoyancy forces that drive plate tectonics, for example, are of fundamental importance for modelling lithospheric stresses and earthquake ruptures. The evolution of lower mantle temperatures and the associated core heat flow, on the other hand, are crucial components in endeavours such as the DeepDyn project, specifically for the geodynamo simulations that aim at modelling the reversal frequency pattern of Earth's magnetic field on geologic time scales. However, a data-driven quantitative understanding of the evolution of buoyancy forces and temperature variations in the mantle is still in its infancy. Despite the great success of tomography and the progress in mineral physics, it remains a challenge to constrain the present-day thermodynamic state of the mantle based on seismic observations. Predictions of mantle structures with realistic length-scales and magnitudes of temperature variations are nevertheless available through geodynamic forward modelling. High-resolution mantle circulation models (MCMs), which assimilate plate reconstructions as surface boundary condition, can nowadays be produced on a routine basis using the available sophisticated numerical tools and modern high-performance computing infrastructures. The robustness of these MCMs then needs to be assessed through either geodynamic-tomographic model comparisons, or by direct comparison of secondary predictions to Earth observations.
I will present our strategy to link hypothetical forward-modeled temperature fields to seismic recordings in a quantitative way. By combining mantle circulation models with mineralogical thermodynamics and global 3-D seismic simulations, synthetic traveltime residuals and free-oscillation spectra can be computed that correctly capture the various non-linearities in the relation to the underlying temperatures. In doing so, it is important to take the uncertainties related to poorly constrained parameters into account when comparing to real data. I will further illustrate how analyzing 3-D wavefield effects in hypothetical Earth models opens up a way to constrain the spectrum of seismic structures in the mantle. Finally, I will touch upon our latest developments and potential future directions in this emerging field of 'virtual seismology' that aims at providing a physically consistent link between geophysical hypotheses and the wealth of information contained in seismic recordings.
mehr Informationen zum Projekt
Link zum nächsten Seminarvortrag
mit Monika Korte