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Subduction zones are a common geologic feature around the world. They are regions where dense oceanic crust descends into the mantle beneath less dense continental crust. Subduction zone margins are characterized by their presence of earthquakes and volcanoes. The longest subduction margin is along western South America where subduction of the Nazca plate is responsible for formation of the Andes. Along this margin there are distinct segments that are described by the changes in geometry of the down-going Nazca plate. The Chilean-Pampean segment is distinguished by a region of flat slab subduction geometry that corresponds to an absence of seismicity and volcanic dormancy.This study uses receiver functions, a passive source seismology tool that helps visualize vertical and lateral velocity changes of large structure at depth, to image the flat slab region. This study is focused on analyzing the lateral velocity changes above the flat slab in order to determine effects of slab geometry on fluid metasomatism in the mantle, indicated by anisotropy. Anisotropy in this region is proposed to originate from serpentinization of peridotite, caused by fluids escaping from the down-going Nazca plate. Constraining anisotropy in this region will provide implications for both seismicity and volcanism on the surface.



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Using Receiver Functions to Study Flat Slab Subduction Zones in Central Chile