Hazards

Because of its elevation (4,392 m), relief, hydrothermal alteration, icecap, glacier-fed radial valleys, and proximity to encroaching suburbs of the Seattle-Tacoma metropolis, Mount Rainier is the most threatening volcano in the Cascades. Its next eruption could produce volcanic ash, lava flows, and avalanches of intensely hot rock and volcanic gases, called pyroclastic flows.

he primary hazard to people from lavaflows is low, but a more serious hazard arises when such flows come into contact with snow and ice.

Mount Rainier erupts explosively to produce small to moderate volumes of tephra, but volumetrically the volcano is primarily effusive.

Pyroclastic flow deposits are not as common at Mount Rainier than at some other Cascades volcanoes, such as Mount St Helens.

Lahars as the greatest of threats that Mount Rainier poses to people and property downstream.

Mount Rainier is behaving about as it has over the last half-million years, so all evidence suggests that the volcano will continue to erupt, grow, and collapse.

Earthquakes near Mount Rainier are continuously monitored by a network of seismometers maintained by the U.S. Geological Survey Volcano Hazards Program and the Pacific Northwest Seismic Network, a part of the University of Washington.

The combination of weak, hydrothermally altered rocks, large quantities of snow and ice, and a seismically active volcano make landslides and rockfalls potential hazards at Mount Rainier.

Scientists study the hydrothermal system at Mount Rainier to learn about volcanic gas emissions at the volcano