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Long-lived partial melt beneath Cascade volcanoes

January 23, 2025

Quantitative estimates of magma storage are fundamental to evaluating volcanic dynamics and hazards. Yet our understanding of subvolcanic magmatic plumbing systems and their variability remains limited. There is ongoing debate regarding the ephemerality of shallow magma storage and its volume relative to eruptive output, and so whether an upper-crustal magma body could be a sign of imminent eruption. Here we present seismic imaging of subvolcanic magmatic systems along the Cascade Range arc from systematically modelling the three-dimensional scattered wavefield of teleseismic body waves. This reveals compelling evidence of low-seismic-velocity bodies indicative of partial melt between 5 and 15 km depth beneath most Cascade Range volcanoes. The magma reservoirs beneath these volcanoes vary in depth, size and complexity, but upper-crustal magma bodies are widespread, irrespective of the eruptive flux or time since the last eruption of the associated volcano. This indicates that large volumes of melts can persist at shallow depth throughout eruption cycles beneath large volcanoes.

Publication Year 2025
Title Long-lived partial melt beneath Cascade volcanoes
DOI 10.1038/s41561-024-01630-y
Authors Guanning Pang, Geoffrey A. Abers, Seth C. Moran, Weston Thelen
Publication Type Article
Publication Subtype Journal Article
Series Title Nature Geoscience
Index ID 70262823
Record Source USGS Publications Warehouse
USGS Organization Volcano Science Center
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