Mount Rainier, located in Pierce County, is an active volcano reaching more than 14,410 feet above sea level. Its majestic edifice looms over expanding suburbs in the valleys that lead to nearby Puget Sound.
At Mount Rainier, lahars are a greater hazards than other volcanic products such as lava and poisonous gases that have been popularized by TV and film. It is considered one of the most dangerous volcanoes in the United States because of the population at risk, the size and frequency of lahars and the fact that we may not have advance warning.
Because of the high level of risk from lahars in the Carbon and Puyallup River valleys, the USGS and Pierce County Emergency Managment have installed a lahar detection and warning system. The system consist of five acoustic flow monitors (AFMs) that detect the ground vibrations of a lahar. Computerized evaluation of data confirms the presence of a flowing lahar and issues an automatic alert to emergency management agencies. Emergency managers can then initiate response measures such as evacuations. This system reduces, but does not eliminate, risk in lahar pathways.
For more information on the warning system please visit the USGS CVO web site. Please visit the planning section of this site to access our Mount Rainier Volcanic Hazards Response Plan and lahar evacuation routes.
