| This report focuses on central Oregon Cascade Range stratovolcanoes of Mount Jefferson, Three Fingered Jack, and the Three Sisters/Broken Top area because of the unique concentration of recent debris flows that have resulted from moraine-dammed lake releases. We evaluate the relevant late Holocene glacier and climate history of the Three Sisters and Mount Jefferson Wilderness Areas between Mount Jefferson and Crater Lake, Oregon and describe conditions that led to formation and failure of Neoglacial moraine dams. We mapped, described, sampled deposits from, and calculated multiple indirect discharge measurements for four debris flows that resulted from breaching of moraine dams to determine and track aspects of flow characteristics as each debris flow moved downstream. The report concludes with a discussion of hazard assessment for existing moraine-dammed lakes in the Three Sisters and Mount Jefferson Wilderness Areas. -- O'Connor, et.al., 2001 |
