Three‐dimensional attenuation model of Sierra Negra Volcano, Galápagos Archipelago

Abstract The shallow magma system beneath Sierra Negra was imaged using attenuation tomographic methods. The t ∗ spectral decay method for P wave phases was used to highlight regions of highQ p − 1which suggest the presence of magma melt. High‐ Q p − 1anomalies ranging from 0.005 to 0.04 are concentrated below the caldera from 0.5 to 10.5 km depths. Attenuation is sensitive to temperature and fluid presence; thus, this high attenuation is interpreted as possible zones of magma accumulation. An imaged shallow body is consistent with geodetic studies on caldera deformation that modeled a magma sill or flattopped diapir of unknown thickness at ∼1 km depth below sea level.