Mount Rainier is a 14,411 foot (4,392 meter)
dormant stratovolcano and has the greatest single-peak
glacier system in the
United States. The state park surrounding the volcano is the fifth oldest national park in the United States and is located in west central
Washington about an hour and a half driving time from the Seattle/Tacoma area.
The base of the volcano occupies approximately 100 square miles and the
lava flows from past eruptions radiate out as much as nine miles. As much as 160 cubic miles (270 cubic kilometers) of lava have been ejected in the past million years.
The last eruption was in 1879, and current activity is limited to steam vents and hot rocks around the
summit and occasional steam explosions on the upper slopes. There are about 30
earthquakes per year, making it the most seismically active volcano in the range aside from
Mount St. Helens.
Surrounding geology indicates that the volcano has a history of massive
avalanches,
debris flows, and shallow seismic activity. About 6000 years ago, a mudflow caused by a
steam explosion was one of the largest known in the world.
Most predictions have Mount Rainier
erupting again within the next 100 years. Unfortunately, this mountain is one of the most dangerous in the Cascade Mountains primarily due to the large
population living at the base of the
mountain. The huge quantities of
ice and
snow (92x10^6 cubic meters and 4.4x10^9 cubic meters, respectively) could melt to form massive debris flows like those seen during the eruption of
Mount St. Helens.