45th anniversary: A look back at the eruption of Mount St. Helens
45th anniversary: A look back at the eruption of Mount St. Helens
Forty-five years ago on May 18, 1980, Mount St. Helens in the state of Washington violently erupted. Here’s a look at volcanoes, then and now.
The 1980 Mount St. Helens eruption began with a steady series of earthquakes in March. By April it began spewing smoke, massive landslides on the north side of the mountain began, as a massive bulge a half-mile wide crept six feet a day up the mountainside.
At 8:32 a.m. on May 18, a magnitude 5.1 earthquake centered below the mountain triggered one of the largest landslides on record, and the mountain erupted.
57 people died as a result of the blast that had enough force that within 3 minutes, the lateral blast, traveling at more than 300 mph, blew down and scorched 230 square miles of forest.
Before erupting in 1980, Mount St. Helens was a steep, conical volcano sometimes referred to as the Mount Fuji of America. During the 1980 eruption, the upper 1,300 feet of the summit was removed by a huge debris avalanche.
Within the first 10 minutes, a plume of ash rose 12 miles high.
The volcanic ash cloud drifted east across the United States in three days and encircled Earth in 15 days.
According to the U.S. Geological Survey, Mount St. Helens was formed during four eruptive stages beginning about 275,000 years ago and has been the most active volcano in the Cascade Range.
Volcano type: Stratovolcano
Most recent eruption: 1980, 2004-2008
Current alert level: Normal
Threat potential: High
The map below shows all where volcanoes are warming/minor activity (yellow) and erupting red as of May 14. The circles show where recent earthquakes have been.
You can find an interactive map of volcanic activity around the world here.
The Axial Seamount is an underwater volcano off the coast of Oregon. Bill Chadwick, a volcanologist and research professor at Oregon State University, along with others, has been monitoring the volcano. Last month they were recording 1,000 earthquakes a day. They are predicting it could erupt sometime in the next year.
The volcano is a mile below sea level and not a threat to humans. When Axial Seamount erupted in 2015, magma came out of the volcano. One of the lava flows was nearly 450 feet thick.
You can learn more about the Axial Seamount at the USGS site here.
California has several active volcanoes. You can learn more about them here.
Sources: U.S. Geological Survey, Geology.com, California Department of Conservation, Oregon State University, earthquakes.volcanodiscovery.com
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