Investigating tomographic resolution in global crustal imaging

Virginia Polytechnic Institute And State University, Blacksburg VA

Investigators

Abstract

Seismic structure of the Earth's crust is important for the understanding of the formation and evolution of continents and ocean basins. The resolution of current global crustal models are limited by highly inhomogeneous data coverage as refraction and reflection experiments and receiver function analysis are sparse in oceanic regions and remote continent interiors. Seismic surface waves can be potentially used to better constrain crustal structure at a global scale as they propagate in the outer shell of the earth and provide best spatial coverage compared with other seismic data sets. However, understanding the lateral and vertical resolution of surface waves in global crustal tomography remains a challenge. This research will integrate development of finite-frequency theory for Moho discontinuity imaging and wave propagation simulations using the Spectral Element Method to investigate resolution limits of ray theory and finite-frequency theory in surface-wave tomography of global crustal structure. The PI will develop finite-frequency theory based on travelling-wave mode coupling for imaging the Moho discontinuity topography in anisotropic media and investigate resolution limits in non-linear global crustal tomography based on phase-velocity sensitivity kernels. The team will quantify the scale-dependence of diffractional effects in global crustal models as well as resolution limits associated with approximations in tomographic theory and imperfect global data coverage. The tradeoff between wavespeed and Moho topography will be analyzed in joint inversions of discontinuity topography and wavespeed structure.