Mount St Helens, Washington, the day before the deadly eruption that would kill 57, 18th May 1980
On May 18, 1980 Mount St. Helens in Washington State erupted in a catastrophic landslide and explosion equal in force to a nuclear bomb. The supersonic blast of gas and molten rock killed 57 people, and reduced hundreds of square miles of forest to wasteland.
"Vancouver! Vancouver! This is it!"
Build-up To The Eruption
Mount St. Helens was last active in the 1850s, but in March of 1980, began experiencing earthquakes, and steam and gas began venting in April. A visible bulge began building up in the volcano, with magma pushing up a dome from beneath the surface and creating immense pressure.
Eruption And Landslide
On the morning of May 18, 1980, an earthquake caused the entire weakened north face of the volcano to slide away, creating the largest landslide ever recorded. This exposed the highly pressurized gasses and molten steam-rich rock in the volcano to lower pressure, causing an explosion that sent a hot mix of lava and pulverized rock toward the nearby Spirit Lake so fast that it actually overtook the avalanching north face.
A pyroclastic flow, or a fast-moving current of hot gas and rock, quickly began spreading out and devastating a fan-shaped area 23 miles across and 19 miles long. The material caused the nearby Spirit Lake and North Fork Toutle River to flash into steam, causing a secondary explosion. The initial blast released energy equal to 24 megatons of TNT, more powerful than most nuclear weapons. Observers of the eruption recalled "house-size boulders" being flung away from the mountain. The blast killed 57 people, including residents of nearby towns, geologists studying the volcano, and photographers recording the eruption.
The landslide also exposed the main vertical vent of the volcano, creating an eruption column that within 10 minutes reached 12 miles into the sky.
The mushroom cloud from the eruption soon reached 15 miles into the atmosphere, eventually depositing ash in 11 U.S. states. A number of additional but smaller eruptions occurred over the next few months, as well.
Forests Wiped Out
A vast swath of the landscape was reduced to wasteland as the blast knocked down about 230 square miles of forest. Many trees in the direct blast zone were snapped off at their bases, and the earth around them was stripped and scorched.
Caught In The Eruption
Photographer Reid Blackburn's car is seen buried after the eruption. Blackburn was among those killed at Coldwater Camp, where the United States Geological Survey was studying Mount St. Helens.
In the weeks leading up to the eruption, the USGS had closed the volcano to the public, and kept it closed despite pressure to reopen it, saving potentially hundreds of lives. Nevertheless, the eruption caused massive flows of material for miles, causing over $1 billion in damage as mud and volcanic material buried structures nearby.
Water in the nearby lakes was also displaced by the massive flows, with the surface of Spirit Lake being raised by about 200 feet. The surfaces of the lake were also partly covered with felled trees for more than thirty years (the above image is from 2012).
Before And After
A model shows the structure of Mount St. Helens before and after the eruption. The mountain's summit was reduced in height by more than 1,000 feet, and its peak was replaced with a mile-wide horseshoe-shaped crater.
The View From Space And Protection
Most of St. Helens' former north side became a rubble deposit 17 miles long, with some areas having a mile of material piled up. In 1982, President Ronald Reagan and Congress established the Mount St. Helens National Volcanic Monument. In 1987, hiking trails around the mountain reopened until renewed volcanic activity forced their temporary closure in 2004.
In the decades since the eruption, the area nearby was left to gradually return to its natural state, but has been slow to fully recover. The main area affected by the blast remains largely barren, and forests that were toppled are still covered in logs from felled trees.
Mount Saint Helens Today
Mount St. Helens experienced a period of volcanic activity from its 1980 eruption until 1991, and again from 2004 to 2008, with gradual lava flows and steam eruptions, as well as a new pressure dome appearing. Since, 2008, however, the volcano has been quiet.