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Three‐dimensional attenuation model of Sierra Negra Volcano, Galápagos Archipelago
Author(s) -
Rodd Rebecca L.,
Lees Jonathan M.,
Tepp Gabrielle
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl069554
Subject(s) - geology , caldera , sill , volcano , magma , magma chamber , diapir , attenuation , seismology , archipelago , petrology , tectonics , oceanography , physics , optics
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.