Three‐dimensional attenuation model of Sierra Negra Volcano, Galápagos Archipelago. Issue 12 (30th June 2016)

• Record Type: Journal Article
• Authors: Rodd, Rebecca L.; Lees, Jonathan M.; Tepp, Gabrielle
• Is Part Of: Geophysical research letters. Volume 43:Issue 12(2016)
• Page Start: 6259
• Page End: 6266
• Publication Date: 2016-06-30
• Subjects: spectral decay -- attenuation -- seismic tomography -- Sierra Negra -- Galápagos -- volcano; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2016GL069554
• Languages: English
• ISSNs: 0094-8276

Abstract

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 high Q p − 1 which suggest the presence of magma melt. High‐ Q p − 1 anomalies 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. Key Points: t* spectral decay method was used to obtain attenuation structure beneath Sierra Negra High‐attenuation anomaly from 0.5 to 10.5 km depth interpreted as possible magma accumulation zones Results support a shallow magma body described and modeled in caldera deformation studies