Mount St. Helens Erupts

Posted by The Home School in the Woods Team on

Can you imagine a volcanic eruption equivalent to 1,600 times the size of the atomic bomb dropped on Hiroshima, Japan? Well, it happened – right here in the United States! 


On March 27th, 1980, Mount St. Helens, located in the Cascade Range of Washington, began a series of volcanic explosions that would eventually cause a massive eruption on May 18th, 1980. This devastating event would be considered the most destructive volcanic eruption recorded in U.S. history. 


Mount St. Helens Pre-1980 Eruption

Mount St. Helens is geologically young compared to its other “brother and sister” volcanic mountains located in the Cascade Region – Mount Hood, Mount Rainier, and Mount Baker


Despite being young, Mount St. Helens is the most active volcano in the Cascade Range and has erupted most frequently out of all of them. Today, Mount St. Helens is considered to be the second most threatening volcano in the United States, right behind Mount Kilauea in Hawaii, according to a USGS report.


It was first discovered by Europeans in 1792 while surveying the northern Pacific Ocean coast. George Vancouver, a Royal Navy Commander, recorded the first sighting of the mountain and named it after Alleyne Fitzherbert, otherwise known as Baron St. Helens, a Britain ambassador to Spain.


Prior to it being founded in 1792, it’s said that Native Americans dwelled in the Cascade Region, but abandoned the area after one of its volcanic eruptions. They gave several names to Mount St. Helens, including “Louwala-Clough,” meaning “smoking or fire mountain.”


There are several legends recorded by Native Americans about the Cascade volcanoes and how they came to be – one of them being the story between two angry brothers who fought over a beautiful woman. 


Legend has it that the woman couldn’t decide between the two brothers, so as a result, they exploded with anger, burning villages and forests in the process. As punishment, the chief gods struck them down along with their lover. One of the brothers is said to have become Mount Adams and the other Mount Hood. Their lover became Mount St. Helens.


In 1800, several explorers entered Mount St. Helens’ territory. They heard reports of an erupting volcano, which geologists would later label as the 57-year-long Goat Rocks Eruptive Period.


From 1805-1806, a Lewis and Clark Expedition member spotted Mount St. Helens from the Columbia River, but never reported an eruption. However, he did report quicksand and clogged channels by Sandy River, which confirmed there had been a recent explosion. 


Over the last 3,000 years, it’s believed that the volcano has exploded numerous times, setting it up for its violent eruption in 1980. Before the 1980 explosion, the volcano was dormant for 123 years. Oddly enough, in 1975, U.S. geologists forecasted that the volcano would erupt “possibly before the end of the century.” 


When Did Mount St. Helens Erupt?

On March 18th, 1980, several small earthquakes began from under the volcano, which indicated the movement of magma below it. As the volcano came out of its hibernation, a total of about 10,000 earthquakes were recorded before its explosion on May 18th. 


On March 27th, its first phreatic eruption – an explosion of steam caused by magma heating underground – occurred. As a result, a new crater was formed about 250 feet wide, which sent an ash column 7,000 feet into the air. Following were several more earthquakes and a series of steam explosions. 


The next day on March 28th, a new crater and blue flame caused by burning gas were observed, as well as several lightning bolts that shot out of the volcano. It wasn’t until 39 other outbursts and strong harmonic tremors were reported on March 30th that geologists notified the governor to declare a state emergency on April 3rd.  


Mount St. Helens Erupts

Even with its many warning signs, scientists had no idea that the volcano would erupt as violently as it did. Many were deceived when the volcano’s activity ceased during the month of May. As a result, much of the public lost interest. On the day of the eruption, Mount St. Helens didn’t show any new activity patterns, indicating nothing out of the ordinary. 


According to the USGS, at approximately 8:32 a.m. on May 18th, 1980, a magnitude 5.1 earthquake struck, which caused the north side of the volcano to slide and erupt laterally. Traveling 110 to 155 miles per hour, the landslide of hot lava moved into one of its near water sources, Spirit Lake, resulting in the largest volcanic landslide recorded in history. 


Within 15 minutes after the eruption, the volcanic ash rose to over 80,000 feet and, as a result, left a significant amount of ash in 11 surrounding states and two Canadian provinces. After its first major explosion, the volcano continued producing earthquakes, outbursts, and steam for another two more months, followed by another large (but not nearly as severe) eruption later that year.


Mount St. Helens Aftermath

In total, fifty-seven people were killed from the blast, including thousands of animals. In addition, 600 square kilometers of forest, along with 200 houses, 47 bridges, 15 miles of railways, and 185 miles of highway were demolished. 


The estimated amount of damage caused was over $1 billion (around $3.4 billion today). President Jimmy Carter surveyed the aftermath and, with horror, said it looked “more desolate than a moonscape.” Scientists later concluded that the thermal energy released during the eruption was equivalent to 26 megatons of TNT. 


Mount St. Helens Today

Since the eruption in 1980, the mountain’s physical form has changed dramatically. Mount St. Helens was once the 5th highest peak in Washington. However, due to the earthquake, which resulted in a landslide on the north side of the mountain, its height was reduced by about 1,280 feet and it now has a crater near its opening, measuring roughly 2,100 feet wide.


Just when everyone thought the volcano went back to being dormant, in September of 2004, it continued to mildly erupt until January of 2008. Today, Mount St. Helens is said to be back in hibernation and is a popular climbing destination for hiking enthusiasts. It continues to be closely monitored and isn’t expected to erupt for another 100-300 years.


Learn More About 20th-Century History

The eruption of Mount St. Helens in 1980 was undoubtedly a catastrophic event that took place in U.S. history. Although its destruction was tragic, we, along with many other Americans, are left in awe of God’s power and His amazing creation. 


Although we don’t cover the eruption of Mount St. Helens in detail, we do have a timeline figure of it that can be found in our 20th Century in America Lap-Pak. In this Lap-Pak, you can find more 20th-century history, including its many wars, scientific inventions, and interesting people!


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