Illuminating mantle structures at Western Galápagos using seismic interferometry by autocorrelation with body waves

Abstract

The Galápagos archipelago is one of the regions with the highest rates of eruption and surface magma emission in the world. Knowledge about the subsurface structure is fundamental for a better understanding of the dynamics of the magmatic systems in the area. However, the details of the internal architecture beneath the archipelago remain poorly constrained at both shallow and deep levels. To shed light on these, we apply seismic interferometry by autocorrelation to records of earthquakes with epicentral distances greater than 30°, obtained from 18 broadband stations deployed around two volcanoes (Cerro Azul and Sierra Negra) located in Western Galápagos, which is characterized by the highest volcanic activity of the archipelago. The methodology we apply results in the identification of the main mantle discontinuities at a wide range of depths with high resolution. We combine the individual results from all stations to construct a representative depth model for the entire region down to a depth of 800 km. Our results reveal coherent reflectivity patterns consistent with previously identified mantle structures and define the extent and location of the Galápagos mantle plume. These findings provide new insights into the mantle structure beneath the archipelago and can be used to improve our understanding of plume processes driving volcanism and its surface expression in the region.