Abstract

Seismic waves generated at moderate to large earthquakes travel through the entire Earth as compressional (P) or shear (S) disturbances and are recorded at seismic stations across the globe. When these seismic waves interact with strong heterogeneities or discontinuities in the Earth’s structure, they can be converted, split and diffracted along or across the boundaries of these structures. Here I will be looking at a couple methods we can use to extract information from the ever-growing seismic databases to learn more about the Earth’s mantle using these complex seismic phases. First, I will present a novel receiver-side diffracted waves (receiver functions) imaging method that allows to get high resolution 3D images of the lithosphere and upper mantle at continental scales under dense seismic deployments. This imaging technique is applied to subduction zone settings, in particular under southern Alaska, where it reveals the fine structure of the transition from oceanic plateau to regular Pacific lithosphere subduction at depth. Then I will discuss ongoing plans to adapt this method to the deep Earth, with a particular focus on the mantle transition zone and its complex topography. I will show preliminary results for a large composite array under Greece and Turkey. Finally, I will discuss some ideas about a potential new methodology to automatically search for suitable source-receiver geometries to study the anisotropy within the deepest parts of the mantle, at the limit between the regular / faster mantle and the large low velocity provinces (LLVP) under Africa and the Pacific at the core-mantle boundary.