Project Info

How well do global seismic models explain Earth’s mantle?

Ebru Bozdag | bozdag@mines.edu

“Recent advances in numerical methods of seismic wave propagation and high-performance computing have opened the door for high-resolution imaging of Earth’s interior from crustal to global scales. We can now iteratively improve seismic Earth models using adjoint tomography, an iterative full-waveform inversion technique, based on 3D wave simulations. 3D simulations dramatically increase the usable amount of data in seismic tomography which is, in the ideal case, the use of entire seismograms in three components. To explore the possibilities and challenges to model every wiggle in seismograms, it is important to check how the phase and amplitude of major seismic phases (e.g., P, S, multiply reflected phases from surface, upper-mantle discontinuities and the core-mantle boundary, etc.) are reproduced by the 3D models of the Earth’s crust and mantle.

In this project, using the recently developed first-generation global adjoint model GLAD-M15 (Bozdag et al. 2016), we propose to evaluate how well we are able to explain the observed seismic waveforms of major and more exotic seismic waves. To this end, we will pick primarily body-wave phases from the dataset of globally distributed 253 earthquakes used in the construction of GLAD-M15 and use statistical tools to asses the fit of the observed and synthetic waveforms. In addition, we will also use ray-theoretical global models (e.g., S362ANI by Kustowski et al. 2008, S40RTS by Ritsema et al. 2011) to see what we benefit from using full waveforms in seismic imaging. Our systematic statistical analysis will help us to gain insight, for instance, whether long-wavelength scattering and multipathing are as important as seismic-wave attenuation by Earth’s anelasticity, the effect of uncertainties in earthquake source parameters in imaging, etc. Ultimately, we will be able to better interpret the composition and the dynamical structure of Earth’s interior.”

More Information

“1) Bozdag, E., Peter, D., Lefebvre, M., Komatitsch, D., Tromp, J., Hill, J., Podhorszki, N. & Pugmire, D., 2016. Global Adjoint Tomography: First-generation model, Geophys. J. Int., 207(3), 1739-1766, doi: 10.1093/gji/ggw356.
2) Zhu, H., Bozdağ, E., Peter, D. & Tromp, J., 2012. Structure of the European upper-mantle revealed by adjoint tomography, Nature Geosciences, doi:10.1038/NGEO1501.
3) https://www.olcf.ornl.gov/2017/03/28/a-seismic-mapping-milestone/
4) https://sciencenode.org/feature/riding-the-3d-seismic-wave.php”

Grand Engineering: Not applicable