Lateral Blast: The Mount St Helens eruption

Today is the 36th anniversary of the historic eruption of Mount St. Helens in Washington State, USA.

The May 18, 1980 eruption was a rare type of volcanic eruption known as a lateral blast. Most explosive volcanoes throw material upwards in an eruption; in the case of Mt. St. Helens the eruption occurred horizontally, releasing pent-up pressure inside the volcano. The eruption obliterated the entire north side of the volcano and resulted in the largest debris avalanche in recorded history.

An incredible series of images showing the explosive flank collapse in the eruption. Source: USGS

The 1980 Mt. St. Helens eruption played an extremely important role in improving our understanding of volcanic eruptions and the magma plumbing system beneath volcanoes. It was the first time pyroclastic flows – clouds of super hot gas, ash and rock that move at hundreds of miles per hour – were studied using modern scientific techniques. Even now, 36 years later, scientists are still publishing new and interesting insights gleamed from the 1980 and later eruptions.

The new central cone inside the older crater. Source: USGS

The volcano is still very much alive today. In recent decades a new volcanic cone has developed in the central crater. Thankfully, scientists from the United States Geological Survey (USGS) are keeping a close eye on the volcano and will hopefully provide warning if a new eruption is imminent.

See how Earth’s 1000+ active volcanoes were formed in this great national Geographic video.


More information:
The feature image at the top of the article was taken by astronaut Tim Peake from the International Space Station in 2016. Source Flickr


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