Core Mantle Boundary Imaging underneath the North Atlantic ocean using teleseismic noise correlations

The seismic signals continuously recorded by large deployments of sensors at the surface of the Earth leads to an unprecedented amount of data that can be used to get a more detailed image of the Earth structure.It has been shown recently that the correlations of seismic noise converge toward the Green's function even at teleseismic distances. P phases reflected at the Core Mantle Boundary are particularly well reconstructed in the mid-period range (3-10 seconds) between distant arrays.In this study we go further by analyzing the phases that travel under the North Atlantic ocean between the US and Europe. We exploit the large set of data deployed in these regions, choosing year 2014 since the Transportable Array (USArray) was located in the Eastern part of the US. The final dataset contains roughly 900 stations distributed on both sides of the ocean.After the extraction of P and PcP phases from cross-correlation signals, we perform a time-delay analysis of these phases and give a first passive image of the core-mantle boundary under the Atlantic. This is a good complement to the analysis performed with earthquake data, since they poorly illuminate the targeted area.We discuss both the advantages and the drawbacks of correlation based imaging using correlation-based signals.