Abstract
Growing evidence indicates that glacial cycles influence volcanic activity, yet the physical mechanisms linking glaciation to magmatic processes in continental arcs remain unclear. We integrate realistic ice and topographic loads with a dike model to evaluate how glaciation modulated magma ascent beneath Mocho-Choshuenco, Chile, during the Last Glacial Maximum (LGM). Ice loading generates a crustal stress “pinch point” that causes dikes rising from lower-crustal reservoirs to stall deeper than under ice-free conditions, effectively shutting off recharge to shallow magma reservoirs. This mechanism explains the ~2-3 km increase in magma storage depth and reduced eruption rates during the LGM without invoking changes in mantle melt supply or reservoir strength. Shutting off recharge also favors magma differentiation, setting the stage for more explosive silicic eruptions during deglaciation once recharge resumes. We identify a parsimonious explanation for glacially-driven shifts in magma composition, storage depth, and eruption rate at Mocho-Choshuenco and arc volcanoes worldwide.
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Data availability
No new data aside from model outputs were generated. The numerical data generated in this study have been deposited in the Zenodo database under accession code: https://doi.org/10.5281/zenodo.18320729.
Code availability
The Matlab codes used to perform dike model simulations and all output files used to produce manuscript figures are publicly available on Zenodo: https://doi.org/10.5281/zenodo.18320729.
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Acknowledgements
The authors would like to acknowledge the following funding sources: NSF EAR-2444709 and NSF EAR-2123211 to M.T., NSF EAR-2123216 to A.H., NSF EAR-2121655 to C.H., and NSF EAR-2121570 to B.S. In addition, the authors thank Joshua Cuzzone for sharing Patagonian Ice Sheet thickness data files.
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Meredith Townsend: writing—original draft, conceptualization, methodology, validation, investigation, visualization. Pablo Moreno-Yaeger: data curation, writing—review and editing. Andrew Harp: methodology, writing—review and editing. Christian Huber: writing—review and editing. Brad S. Singer: writing—review and editing.
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Townsend, M., Moreno-Yaeger, P., Harp, A. et al. Stress pinch points from glacial loading modulate magma ascent and storage in continental arcs. Nat Commun (2026). https://doi.org/10.1038/s41467-026-69485-y
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DOI: https://doi.org/10.1038/s41467-026-69485-y
