A helicopter delivers supplies to a U.S. Geological Survey field crew conducting Electronic Distance Measurement surveys on the flank of South Sister volcano in the central Cascades of Oregon.

Photo by Lyn Topinka, 1986 (U.S. Geological Survey).

This image is made available as a Public Domain Work, but proper attribution is appreciated.

Galleries: Fieldwork | Volcano Monitoring

Keywords: volcano monitoring | deformation | stratovolcano | field work | volcanologist | EDM

Three Sisters