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The prevalence and significance of offset magma reservoirs at arc volcanoes

June 15, 2020

Determining the spatial relations between volcanic edifices and their underlying magma storage zones is fundamental for characterizing long-term evolution and short-term unrest. We compile centroid locations of upper crustal magma reservoirs at 56 arc volcanoes inferred from seismic, magnetotelluric, and geodetic studies. We show that magma reservoirs are often horizontally offset from their associated volcanic edifices by multiple kilometers, and the degree of offset broadly scales with reservoir depth. Approximately 20% of inferred magma reservoir centroids occur outside of the overlying volcano’s mean radius. Furthermore, reservoir offset is inversely correlated with edifice size. Taking edifice volume as a proxy for long-term magmatic flux, we suggest that high flux or prolonged magmatism leads to more centralized magma storage beneath arc volcanoes by overprinting upper crustal heterogeneities that would otherwise affect magma ascent. Edifice volumes therefore reflect the spatial distribution of underlying magma storage, which could help guide monitoring strategies at volcanoes

Citation Information

Publication Year 2020
Title The prevalence and significance of offset magma reservoirs at arc volcanoes
DOI 10.1029/2020GL087856
Authors Allan H. Lerner, Daniel O'Hara, Leif Karlstrom, Susanna K. Ebmeier, Kyle R. Anderson, Shaul Hurwitz
Publication Type Article
Publication Subtype Journal Article
Series Title Geophysical Research Letters
Index ID 70211079
Record Source USGS Publications Warehouse
USGS Organization Volcano Science Center