Global Full-Waveform Inversion: Exploring the Earth from Crust to Core Based on 3D Numerical Simulations

Ebru Bozdag, assistant professor of geophysics at the Colorado School of Mines, presents a colloquium. Accurate and high-resolution images of Earth’s interior are crucial to improve our understanding of the inner dynamics of our planet. Global adjoint tomography is one of the extreme projects in seismology due to the intense computational requirements and vast amount of data that can potentially be assimilated in inversions. GLAD-M15 is the first-generation global adjoint tomography model which has transverse isotropy confined to the upper mantle where crust and mantle were inverted simultaneously. After GLAD-M25, which is the successor of GLAD-M15, we now explore more complete parameterizations including surface-wave azimuthal anisotropy, anelasticity, etc. while increasing the database in complementary inversions. Meanwhile we define and adapt new measurement techniques, such as exponentiated-phase and double-difference measurements, to improve the resolution and speed up convergence in global full-waveform inversions. The ultimate aim is to go down to 1 Hz in global simulations to perform whole-Earth inversions including the core and assimilate all available seismic data.