Mount Rainier is an episodically active volcano and has the greatest single-peak glacial system in the United States. Numerous glaciers radiate from its summit and slopes. Volcanic activity began between one half and one million years ago. At one time, lava flows on opposite sides of the mountain probably projected more than 1,000 feet above the present summit at Columbia Crest which rises 14,410 feet above sea level on the rim of the recent lava cone. The upper portion of the volcano's cone was likely removed by explosions and landslides.

Mount Rainier, the highest (4392 m) volcano in the Cascade Range, towers over a population of more than 2.5 million in the Seattle Tacoma metropolitan area, and its drainage system via the Columbia River potentially impacts another 500,000 residents of southwestern Washington and northwestern Oregon. Mount Rainier is the most hazardous volcano in the Cascades in terms of its potential for magma water interaction and sector collapse, and major eruptions or debris flows even without eruption. It poses significant dangers and economic threats to the region but despite such hazards and risk, Mount Rainier has received little study.

Mount Rainier - Decade Volcano
In 1989 the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) established a Task Group for the International Decade for Natural Disaster Reduction. The Task Group conceived the idea of selecting several volcanoes for focused study during the next decade as "Decade Volcano Demonstration Projects," established criteria for a "Decade Volcano," and solicited nominations. The IAVCEI accepted the nominations of seven volcanoes in developing countries and two in the U.S. Mount Rainier and Mauna Loa. Mount Rainier was chosen to be studied because it is representative of one or more volcanic hazards: it is geologically active as evidenced by surface manifestation of heat (geothermal activity), it has had recent volcanic events (last eruption was about 150 years ago), and it is likely to erupt again, based on past history; its location poses significant hazards to a heavily populated area; it is a well known volcano (a number of research publications have been written on it); it is politically and physically accessible for study; and its volcanic geology is well exposed.

In 1992 NPS staff participated with other agencies and individuals to develop a science plan through the National Academy of Sciences, for organizing the needed research to evaluate the hazards and risks associated with Mount Rainier and for developing communication efforts of the risks for appropriate planning activities. The science plan was published in Mount Rainier Active Cascade Volcano and is available in the park library. Several studies related to geologic hazards are being conducted by the USGS, other federal and state agencies, and academic institutions.

Additional Mount Rainier Volcano Information:
Mount Rainier Volcano - USGS description, history, and points of interest.
History and Hazards of Mount Rainier - T. Sisson, 1995, USGS
Volcano Hazards from Mount Rainier, revised 1998 - Hoblitt, et. al., 1998, USGS
Mount Rainier Eruptive History - USGS
Volcanoes of Lewis and Clark: Mount Rainier - USGS