March 18, 1980 marked the eruption of Mount St Helens, a symmetrical stratovolcano located in Skamania County, in the U.S. state of Washington. The eruption wasn’t anticipated but didn’t proceed in an unexpected manner. It led to the death of thousands of animals and about 50 people. Here are some interesting facts about Mount St Helens Eruption in 1980.
Named after a British diplomat
The name St. Helena was named after a British diplomat named Lord St. Helens. St. Helens was a friend the Volcanologist, George Vancouver, who surveyed the volcanic region of Mount St Helens.
It was usually a peaceful mountain
Throughout the 20th century, the Mount St Helens volcano was peaceful and also a popular recreation spot.
Mountain in the “ring of fire”
The Mount St Helens volcano is 154 km south of the city of Seattle. It is a part of the mountain range, Cascade Range that occupies western North America. In addition, it is a part of the “ring of fire” mountains in the Pacific. There are the mountains that show high seismic and volcanic activity.
Geologists knew it was going to erupt
Geologists had observed the underground activity in the area and knew that Mount St Helens would erupt one day. However, they didn’t know when it would erupt. It was only predicted that it will erupt after observing an increase in the seismic activity.
The last words “This is it!”
Volcanologist, David Johnston was camping within the blast zone when the mountain erupted. He had observed that the mountain was bulging. When a 5.1 magnitude earthquake hit the site, he radioed his peers, “This is it!” These were his last known words.
The north face collapse
On March 18th, a 5.1 magnitude earthquake led to the collapse of the north face of the mountain. This caused the largest landslide known to humans. The debris from the landslide slid at the high speeds and hit the Spirit lake that caused waves of up to 180 meters.
Everything within 12 km of the blast was wiped out almost instantly
The Mount St Helen’s eruption of 1980 is often called the most disastrous volcanic eruption in the United States. The collapse of the north face of the mountain made way for the lava, high pressure gas and rocks towards the Spirit lake. The eruption rose to as high as 80,000 feet and spewed ash spread to 11 states of the US. The mudslides traveled almost 50 kilometers and also reached the Columbia River, which is 80 kilometers from the site of eruption.
Intense pyroclastic flows
Mount St Helens spewed out pyroclastic flows. A pyroclastic flow is a fast-moving current of hot gas, lava and stones that moves at the speed of about 100 km/h on average but can also reach speeds up to 700 km/h.
Continued eruptions that created domes
Small lava eruptions from Mount St continued in the years 1980 – 1990, which caused the formation of lava dome on the surface of the crater. It was inactive for several years until 2004.
Earthquakes and eruptions lasted for 2 months
After the eruption of the volcano, a series of earthquakes of magnitude nearing 4 rocked the area for 2 months.
Melting of glaciers
The heat generated from the eruption of Mount St Helens caused the glaciers to and the snow of the mountains nearby melt.
Most destructive volcano in the US
The 1980 Mount St. Helens eruption was the most destructive in U.S. history. Fifty-seven people died, and thousands of animals were killed. The 1980 eruption of Mount St Helens destroyed more than 200 homes and 297 kilometers of roads. It was estimated that the the total damage worth was $1.1 billion.