the north face base camp flip flop Helens still a scene of devastation 35 years after eruption News in Science ABC Science
Earth image It’s now been 35 years since the Mount St. Helens volcano erupted in a spectacular explosion. The scars of that event are still clearly evident in this Landsat 8 image.
The eruption, which occurred on May 18, 1980, caused a cataclysmic collapse of the northern flank; an avalanche and an explosion, which killed 57 people and devastated hundreds of square kilometres of the surrounding landscape.
Countdown to disasterMount St. Helens is an active stratovolcano located in the Cascade Ranges in Washington State. The Cascade Volcanic Arc is part of the Pacific Ring of Fire, which includes over 160 active volcanoes.
By March 1980, geologists had been monitoring ever increasing rumbles inside the awakening volcano for several months with the mountain experiencing small earthquakes and a growing number of steam vents.
By the end of April, the mountain’s northern flank began to bulge.
The worsening volcanic activity reached its crescendo at 8:32 on the morning of May 18, when an earthquake measuring 5.1 triggered an explosive eruption and the massive collapse of the northern face of the mountain in one of the largest known debris avalanches in recorded history.
The eruption blew off the top of the mountain, released a huge flow of magma, generated a massive pyroclastic flow that flattened everything in its path over an area of 600 square kilometres,
and set forth floods of debris and melt water, known as lahars, which thundered down river valleys.
In the eruption’s wake, denuded trees lay like matchsticks, clouds of ash covered the landscape, and the mountain’s 2950 metre high summit had been reduced to 2550 metres and replaced with a 1.6 kilometre wide horseshoe shaped crater.
The eruption also destroyed 250 homes, 47 bridges, 24 kilometres of railways, and 298 kilometres of roads in what was the deadliest and most economically destructive volcanic event in the history of the United States.
Scientists estimate the eruption released over 1.5 million tonnes of sulfur dioxide into the atmosphere, and recorded a Volcanic Explosivity Index of five.
The image was assembled from data acquired by the Operational Land Imager on Landsat 8 and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on the Terra satellite.
A view of the north face of Mount St Helens before the eruption of 1980(Source: USGS)
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