Seismic investigation of the upper mantle of western South America
The first part of this project uses teleseismic PP waves whose midpoints most densely populate the area between 10° S and 15°S. Seismic profiles at those two latitudes allow us to make interpretations regarding subsurface features from the Nazca Plate, across the Peru-Chile Trench and beneath the Andean Province. This project uses earthquake data from 1990-2016. Stacks reveal a discontinuity in the 60-90 km depth range across the Nazca plate, Peru-Chile Trench, and Andean Province. This is interpreted as the Hales discontinuity. Further east beneath the Amazon Basin, the continental Moho is observed in depth ranges of 30-50 km. We interpret a lithosphere-asthenosphere boundary (LAB) at 190-200 km depth across the trench beneath the Andes that may be the basement of a LAB transitional zone. The second part of this project uses receiver function (RF) data to study features in southern latitudes of the South American continent near receiver stations. Two phases of RFs are used: Ps and Sp. Ps processing includes an innovative Wavefront Iterative Deconvolution (WID) method to isolate phases of interest. Ps results reveal that previous works are probably scattered, misinterpreted data. Despite this, a shallow 410-km discontinuity is observable in flat slab regions of the continent; alternatively, the 410-km discontinuity is deeper in non-flat slab regions. Sp stacks are also sparse but show an observable Moho at 80 km depth beneath the Andes and a LAB of 120 km depth; this may be the beginning of the LAB transitional zone.