Volcano Information

    Mount Rainier
    Volcanic Alert Level: NORMAL Aviation Color Code: GREEN

    • Status: Mount Rainier is monitored by the Cascade Volcano Observatory and is at a background level of activity.
    • Volcanic History Overview: Mount Rainier, at 4392 m the highest peak in the Cascade Range, forms a dramatic backdrop to the Puget Sound region. Large Holocene mudflows from collapse of this massive, heavily glaciated andesitic volcano have reached as far as the Puget Sound lowlands. The present summit was constructed within a large crater breached to the north during the a mid-Holocene eruption as a result of the collapse of a once-higher edifice. Several postglacial tephras have been erupted from Mount Rainier; tree-ring dating places the last recognizable tephra deposit during the 19th century. The present-day summit cone was formed during a major mixed-magma explosive eruption about 2200 years ago and is capped by two overlapping craters. Extensive hydrothermal alteration of the upper portion of the volcano has contributed to its structural weakness; an active thermal system has caused periodic melting on flank glaciers and produced an elaborate system of steam caves in the summit icecap.
    • Location: Western US, WA

      Latitude: 46.853
      Longitude: -121.76
      Elevation: 4392 m

      Recent Eruption: Possibly in 1894 and 1840's, larger eruption certain 1,000 years ago
    • Hazard Assessments: Hoblitt, et.al., 1998, Volcano Hazards from Mount Rainier, Washington, Revised 1998, USGS Open-File Report 98-428.
    • Link to monitoring data: The Pacific Northwest Seismic Network