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 earthquake
s 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 avalanche
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 erupt
ing 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
(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