Integrating petrochronology, magma dynamics, and volcanic unrest at the Three Sisters volcanic complex. In this NSF-funded project, we conducted gravity surveys between 2019 and 2024 at the Three Sisters volcanic cluster in Oregon to better understand what lies beneath this actively uplifting region. We identified low-density zones in the subsurface that point to a large hydrothermal system. Our results also suggest that a magmatic mush could be stored beneath the surface without producing a detectable gravity signal. We propose that occasional injections of magma from depth supply heat and gas to this hydrothermal system, a pattern consistent with what has been observed at other volcanoes.

Collaborators: Nathan Andersen (USGS CVO), Joe Dufek (U. Oregon), Annika Dechert (U. Oregon).

Status: completed.

Publication:
Le Mével, H., Andersen, N. L., Dechert, A. E., & Dufek, J. (2026). The magmatic‐hydrothermal system of the three sisters volcanic cluster, Oregon, imaged from field gravity measurements. Journal of Geophysical Research: Solid Earth, 131(1), e2025JB031886. doi:/10.1029/2025JB031886