Postglacial lahars from Mount Rainier Volcano, Washington

Preeruption conditions and timing of dacite‐andesite magma mixing in the 2.2 ka eruption at Mount Rainier

“…Mount Rainier, in the Washington Cascades, has produced 11 distinctive pumiceous tephra layers [Crandell, 1971;Mullineaux, 1974;Pringle et al, 1994] and 25 additional lithic tephra layers [Pringle et al, 1994] over the last 10,000 years. The most voluminous of these tephra fall layers (•0.3 km 3) is layer C (2200 years B.P.…”

Alteration, slope-classified alteration, and potential lahar inundation maps of volcanoes for the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Volcano Archive

“…Hydrothermal alteration occurs when heated groundwater interacts with volcanic rocks and produces argillic and phyllic minerals such as alunite, kaolinite, smectite, and sericite, which has been shown to weaken volcanic edifices and increase the potential for triggering lahars (Crandell, 1971;Scott and others, 1995). For example, although rain was the primary trigger of the Casita volcano lahar, the volcanic sector at the origin of the collapse consisted primarily of hydrothermally altered, smectite-rich, volcanic rock (Devoli and others, 2009;Opfergelt and others, 2006;others, 2005, Vallance andothers, 2004).…”

Geologic map of the Mount Adams volcanic field, Cascade Range of southern Washington

“…The greatest hazard at Mount Adams, in common with many other large andesitic stratovolcanoes (Crandell, 1971;Scott and others, 1992), is not from volcanic activity as such but from debris avalanches and debris flows of various origins. A summit eruption or even a shallow intrusion beneath the icecap could promote rapid melting of snow and ice that might lead to high-velocity floods cascading down steep walls of the cone.…”