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9 lis 2016 · Volcano hazard map showing the extent of lahar hazards in towns and valleys surrounding Mt. Rainier in Washington. Image credit: USGS.
- The Eruption History of Mount Rainier
Map shows simplified geology of Mount Rainier volcano,...
- The Eruption History of Mount Rainier
7 lis 2023 · Map shows simplified geology of Mount Rainier volcano, Washington. Ka indicates thousands of years before present. (Public domain.)
Since the last ice age, several dozen explosive eruptions spread tephra (ash, pumice) across parts of Washington. The last magmatic eruption was about 1,000 years ago. Extensive hydrothermal alteration of the upper portion of the volcano has contributed to its structural weakness promoting collapse.
Mount Rainier, Washington: Mount Rainier, the highest (14,410 feet) and third-most voluminous volcano in the Cascades after Mounts Shasta and Adams, dominates the Seattle-Tacoma area, where more than 1.5 million know it fondly as "The Mountain".
U.S. Geological Survey (USGS) research shows that Mount Rainier is one of our Nation's most dangerous volcanoes. It has been the source of countless eruptions and volcanic mudflows (lahars) that have surged down valleys on its flanks and buried broad areas now densely populated.
Mount Rainier is an active volcano that first erupted about half a million years ago. Because of Rainier's great height (14,410 feet above sea level) and northerly location, glaciers have cut deeply into its lavas, making it appear deceptively older than it actually is.
The largest known explosive eruption of Mount Rainier occurred between about 30,000 and 100,000 years ago and is recorded by a pumice deposit that has been recognized northeast, east, and southeast of the volcano.
