Arts & Entertainment
Today In History: Mount St. Helens Erupts
On March 27, 1980, the volcano erupted for the first time in over 100 years blanketing a 230 mile devastated area with hot debris.
OCEANSIDE, CA — On March 16, 1980, Mount St. Helens showed the first sign of activity that occurred as a series of small earthquakes. On March 27, hundreds of additional earthquakes happened, the volcano produced its first eruption in over 100 years. Steam explosions blasted a 200 to 250ft wide crater through the volcano's summit ice cap and covered the snow-clad southeast sector with dark ash.
Mount St. Helens northern flank suffered a massive landslide. Its removal resulted in immediate depressurization of the volcano's magmatic system and triggered powerful eruptions that blasted laterally through the sliding debris and removed the upper 300 m (nearly 1,000 ft) of the cone.
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This lateral blast of hot material overtook the debris avalanche; it accelerated to at least 300 miles per hr. Within a few minutes after onset, an eruption cloud began to rise from the former summit crater. Within less than 15 minutes it had reached a height of more than 15 miles or 80,000 ft.
The lateral blast devastated an area nearly 19 miles from west to east and more than 12.5 miles northward from the former summit. In an inner zone extending nearly 6 miles from the summit, almost no trees were left standing. This was once dense forest. Just beyond this area, all standing trees were blown to the ground, and at the blast's outer limit, the remaining trees were thoroughly seared. The 230 mile devastated area was blanketed by a deposit of hot debris carried by the blast.
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Learn more about the Mount St. Helens eruption by visiting the U.S. Geological Survey website.
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