Complex Shear‐Wave Splitting Behavior in the Northern Andes and Possible Implications for Mantle Flow Around the Caldas Tear

We investigate shear‐wave splitting of SKS and SKKS phases from teleseismic earthquakes to study the anisotropic structure of the lithosphere and upper mantle beneath the Colombian Andes. This area is shaped by complex interactions between the subducting Nazca and Caribbean plates beneath the South American plate. A recent broadband deployment across the Colombian Andes (MUSICA) provides insight into the dynamic response of the mantle to these adjacent slabs, especially across an offset in the Wadati‐Benioff Zones known as the Caldas Tear. We interpret observed splitting measurements as the result of three interacting flow components within the mantle: (a) entrained trench‐perpendicular corner flow in the mantle wedge, (b) mantle flow through the Caldas Tear, and (c) trench‐parallel flow well east of both subducting plates. While our results are complex, our observed anisotropic patterns in this study are consistent with recent modeling efforts to understand how mantle flow might pass through flat‐slab tears. These findings provide new insight into the heterogeneous anisotropic structure beneath the Colombian Andes at high spatial resolution, and further our understanding of the linkage between complex subduction geometry and surrounding geodynamics.