Resolution and Covariance of the LLNL-G3D-JPS Global Seismic Tomography Model: Applications to Travel time Uncertainty and Tomographic Filtering of Geodynamic Models

Abstract

1 million free parameters, creating matrices with >1 trillion elements. Given the scale of the problem and computational limitations, we used a custom method to calculated impulse responses at every node in the earth model and produced sparse, yet representative, resolution and covariance matrices that can be practically used for several real applications. We apply the matrices to real problems as example use cases. Utilizing the covariance matrix, we computed traveltime uncertainties for thousands of P waves emanating from (or coming to) specified points around the globe and constructed maps of the traveltime error to illustrate the variability of path-specific traveltime uncertainty. Utilizing the resolution matrix as a tomographic filter, we converted geodynamically derived renditions of Earth structure to images that may be visible through the often-distorted lens of seismic tomography.