Toward a three-dimensional tomographic model of the Pacific upper mantle with full resolution and uncertainties

<p>Tomographic models suffer from unevenly distributed noisy data and therefore have complicated resolution and uncertainties that can hinder their interpretation. Using linear Backus & Gilbert inversion, it is possible to obtain tomographic models with resolution and uncertainties in a single step. Using such a method, we aim to produce a three-dimensional tomographic model of the Pacific upper mantle from surface-wave data. To linearise the forward problem, we use finite-frequency theory to describe the sensitivity of surface-wave phase-delays to the three-dimensional shear-wave velocity. We build a data-base of phase-delay measurements for surface-waves that cross the Pacific Ocean. We estimate the data uncertainties caused by measurement errors using a multitaper technique and those caused by poor knowledge of the seismic source and crust by a Monte-Carlo method. Using the Backus & Gilbert approach, the phase-delay dataset, and the data uncertainty estimates, we obtain a model of the shear-wave velocity of the Pacific upper mantle together with its three-dimensional resolution and uncertainties. These allow us to discuss, using robust statistical arguments, the existence and the three-dimensional organisation of structures we expect to see in the Pacific upper mantle, such as plume-like upwellings or small-scale sub-lithospheric convections.</p>