Why did I write about the eruption of Mount St. Helens?

The eruption of Mount St. Helens in 1980 was one of the most environmentally destructive in world history. It was the most powerful natural disaster ever recorded in America, more powerful than Hurricane Katrina in 2005 or the San Francisco Earthquake of 1906.

And yet many people under the age of thirty have barely even heard of it. How can that be?

We tend to remember disasters that result in large numbers of human deaths. The St. Helens eruption destroyed 230 miles of wilderness. But because the mountain was surrounded mostly by forests, it claimed far fewer lives than many other destructive volcanoes. Fifty-seven people died in St. Helens. More “famous” volcanoes like Vesuvius and Krakatoa killed tens of thousands.

But the eruption of St. Helens was very important, and not just because it happened right here in the United States. It was the first volcano that scientists could study closely while it was revving up for its eruption. Today, volcano scientists (called volcanologists) have a much better understanding of volcanoes than they did in 1980. And that is because of the lessons learned from St. Helens.

What happened when St. Helens erupted?

On the morning of May 18, Mount St. Helens erupted with the force of a one-megaton nuclear bomb, which is equal to ten million tons of dynamite. The front of the mountain actually shattered apart and collapsed with rocks tumbling down the mountain in a massive avalanche. The explosion created a cloud of ash, smoke, and gas that shot more than twelve miles up into the sky. It triggered one of history’s biggest landslides. It was fifty miles wide. The wave of mud and debris and melted ice raced down the mountain and swept away bridges, thousands of trees and logs, cars, houses, bulldozers, and roads.

The eruption spewed a staggering amount of ash — 520 million tons of it. The ash blew eastward, across the United States. In the city of Spokane, Washington, 350 miles away, the ash caused complete darkness. As far away as Montana, ash from St. Helens ruined crops, caused car accidents, and clogged airplane engines.

Did the eruption really take people by surprise?

Yes, the eruption was a surprise, and to me, that was the most incredible part of the story. There were so many warning signs — thousands of earthquakes (yes, thousands) between March 20 and the eruption on May 18. There were dozens of steam explosions, some that lasted for hours.

Huge cracks formed in the mountain. Near the summit, the mountain was actually bulging out from the pressure inside it. Just two years before, two scientists wrote a research paper warning that St. Helens was likely to erupt in the coming years.

And yet, the eruption on the morning of May 18 was a true surprise, even to scientists. The mountain had quieted down in the weeks right before. Most scientists had thought there would be some very dramatic warning before it exploded. But that warning never came. One minute the mountain was peaceful, and the next it erupted with a violence that few had imagined.

Are scientists better able to predict eruptions today?

Yes. Today scientists have far better tools for studying volcanoes. They have computer programs that can analyze huge amounts of data in seconds. They have lasers that can detect whether melted rock — magma — is rising up through the volcano.

But what truly changed volcano science was the eruption of Mount St. Helens. Scientists from all around the world have studied every second of that eruption. This work has helped scientists better understand the warning signs that often lead to volcanic eruptions.

Could St. Helens erupt again?

Yes. In fact, it already has many times since 1980. Some of the eruptions have released huge clouds of ash into the sky. In 2004, it spewed 26 billion gallons of lava. (How did they measure that? I wish I knew!) But none has come close to the fury of the 1980 eruption.

What are the world’s most dangerous volcanoes?

There are 1,500 volcanoes in the world that could be active, from the lava-spewing Kilauea of Hawaii to the steaming Katla of Iceland to the quietly beautiful Mount Fuji in Japan.

About 160 of the world’s most active volcanoes are located in a horseshoe-shaped area surrounding the Pacific Ocean. This area is called the Ring of Fire.

The Cascade mountain range, where St. Helens is located, is part of this ring.

Any active volcano is dangerous. But what makes a volcano perilous to humans is mainly its location. Volcanoes located near big cities are far more dangerous than those in remote areas. The eruption of Mount St. Helens could have killed thousands if it had been near a more crowded area.

And here are some more intriguing facts I found about Mount St. Helens:

Height of eruption cloud: The main volcanic cloud rose to between 12 and 15 miles into the sky, into the Earth’s stratosphere.

Number of earthquakes before eruption: More than 2,000

Area destroyed by eruption: About 230 square miles (more than three times the size of Washington, DC)

Size of landslide: 23 square miles

Depth of landslide: Roughly 100 feet

Speed of landslide: 70–150 miles per hour

Distance traveled by ash cloud: Ash could have circled the globe three times; small amounts of ash fell over 22,200 square miles.

Height of St. Helens before eruption: 9,677 feet (It was the fifth-tallest mountain in the Cascades.)

Height after eruption: 8,363 feet (It is now the fourteenth tallest.)

Number of bridges destroyed: 27

Miles of highway destroyed: 185

Number of trees destroyed: Roughly 3 million