11 Explosive Facts About Mount St. Helens

A column of ash and volcanic gas erupts from Mount St. Helens on May 18, 1980.
A column of ash and volcanic gas erupts from Mount St. Helens on May 18, 1980.
Robert Krimmel, USGS // Public Domain

When a strong earthquake triggered Mount St. Helens’s colossal volcanic explosion on May 18, 1980, the blast obliterated every object within a six-mile radius. It remains the United States’s most powerful, and the world’s fifth most destructive, volcanic event in recent history. Here are more facts to mark the 40th anniversary of the Mount St. Helens eruption. 

1. Mount St. Helens is part of the Pacific Ring of Fire.

Mount St. Helens is part of the chain of 160 active volcanoes around the Pacific Rim known as the Ring of Fire. It sits on top of the subduction zone where the oceanic Juan de Fuca tectonic plate slips under the North American plate. It’s a stratovolcano, also known as a composite volcano: a steep-sided volcano with a cone made up of layers of lava, ash, and debris. Stratovolcanoes are considered more dangerous than shield volcanoes, which are created by slow lava flows and feature more gentle slopes. (The Hawaiian islands are a chain of shield volcanoes.) Stratovolcanoes tend to erupt explosively, and their steep sides are prone to landslides, avalanches, and sometimes even collapse.

2. Mount St. Helens was named for a British diplomat.

Mount St. Helens as it appeared before the May 18, 1980 eruption.Rick Hoblitt, USGS // Public Domain

Mount St. Helens isn’t named after a saint—it was named by George Vancouver, the British naval explorer who charted the Pacific Northwest in the 1790s, for his friend, Baron St Helens. The baron, whose given name was Alleyne Fitzherbert, served as a diplomat for the British government in Brussels, Paris, Russia, Spain, and elsewhere. Among some of the indigenous people of the Pacific Northwest, the volcano is known as Louwala-Clough (Smoking Mountain), Lawetlat’la (Smoker), and Nsh' Ak'w (Water Coming Out).

3. Mount St. Helens has been erupting for a long, long time.

Mount St. Helens has gone through a number of eruptive stages over its lifetime, beginning 275,000 years ago. That’s relatively young for a volcano—a number of volcanoes formed by the Hawaiian hot spot are tens of millions of years old. However, volcanoes change drastically over their lifetimes: Most of the modern Mount St. Helens cone that is visible now formed during the last 3000 years, according to the U.S. Geological Survey.

4. Mount St. Helens is the most active volcano in the Cascade Range.

Mount Baker, Mount Shasta, Mount Rainier, Mount Hood, Glacier Peak, and Lassen Peak are also active volcanoes in the Cascades, but the most recent activity among them was at Lassen Peak in the early 1900s. Mount St. Helens is the youngest among the Cascade volcanoes, too, which is why it shows fewer signs of erosion than neighbors like Mount Rainier or Mount Hood.

5. The cataclysmic 1980 explosion of Mount St. Helens was the volcano’s first major eruption in more than 100 years.

Mount St. Helens erupts on May 18, 1980.Robert Krimmel, USGS // Public Domain

Prior to 1980, the last major explosive eruption of Mount St. Helens on record occurred in 1800. There were several minor explosions throughout the early 19th century up until 1857, when the volcano became dormant once again. This period of volcanic activity created what became known as the Goat Rocks Dome, which was part of Mount St. Helens’s distinctive silhouette until it was destroyed in the 1980 eruption.

6. The 1980 Mount St. Helens eruption is still the most powerful volcanic eruption in U.S. history.

On the morning of May 18, 1980, a 5.1-magnitude earthquake caused a massive landslide—the largest debris avalanche in history—on the north face of Mount St. Helens. In the volcanic eruption that followed, the lateral blast destroyed every living and non-living thing within six miles of the volcano. The deadly pyroclastic surge—a fast-moving, super-hot cloud of ash, rock, and volcanic gas—traveled as much 18 miles away from the blast. The hot lava, gas, and debris mixed with melting snow and ice to form massive volcanic mudflows that surged down into valleys with enough force to rip trees from the ground, flatten homes, and completely destroy roads and bridges. Rivers rose rapidly, flooding surrounding valleys. Ash fell from the sky as far away as the Great Plains. Two-hundred-and-fifty miles away, ash blanketed Spokane, Washington, in complete darkness.

7. A Mount St. Helens volcanologist likely saved hundreds of lives.

Fifty-seven people died as a result of the eruption, though the number could have been much higher. Volcanologist David Johnston was an advocate for restricting access to the volcano when, in early 1980, an increase in seismic activity signaled that an eruption might be imminent. Johnston died when the observation post from which he was monitoring Mount St. Helens was destroyed. “The volcano-monitoring effort of which Dave was part helped persuade the authorities first to limit access to the area around the volcano, and then to resist heavy pressure to reopen it, thereby holding the May 18 death toll to a few tens instead of hundreds or thousands,” according to the authors of the 1982 U.S. Geological Survey professional paper about the disaster.

8. The eruption changed the appearance of Mount St. Helens forever.

Prior to the 1980 eruption, Mount St. Helens had a symmetrical, snow-covered cone that gave it the nickname the “Mount Fuji of America.” The peak stood 9677 feet tall. But the lateral blast changed its appearance considerably: The top 1300 feet of the summit was destroyed by the eruption and landslide. Now, the volcano sports a north-facing, horseshoe-shaped crater that contains a lava dome and a glacier.

9. Mount St. Helens was made into a national volcanic monument in 1982.

Ash from the May 18, 1980 eruption of Mount St. Helens covers the ground at a farm located 180 miles from the volcano.Lyn Topinka, USGS // Public Domain

Two years after the devastating eruption, Congress turned the area around Mount St. Helens into a 110,000-acre national volcanic monument for research and recreation. Located within the Gifford Pinchot National Forest, it’s managed by the U.S. Forest Service. Visitors can hike, camp, fish, and more, though hikers need a special permit to climb up to the summit. (This isn't permitted when the volcano is experiencingunusually high activity, of course.) They can also tour the Johnston Ridge volcanic observatory and Ape Cave, a lava tube formed almost 2000 years ago.

10. Mount St. Helens has been shrinking.

A 1982 survey measured the summit of the volcano at 8365 feet tall. As of 2009, it measured 8330 feet. The shrinkage is probably the result of erosion and collapses of crater walls.

11. Mount St. Helens is not done erupting.

The U.S. Geological Survey still rates Mount St. Helens’s threat potential as “very high” because of the potential for eruptions and the number of nearby communities that those eruptions could impact. The volcano is just over 50 miles from Portland, Oregon, and less than 100 miles from Seattle. The 1980 eruption destroyed all structures around the nearby tourist destination of Spirit Lake, including more than 200 houses and cabins. Mount St. Helens’s most recent volcanic activity stretched from 2004 to 2008, during which the volcano grew a new lava dome and periodically released plumes of steam and ash. There were few significant explosions before the volcanic activity died down in 2008.

While the U.S. Geological survey warns that Mount St. Helens will likely explode again during our lifetimes, the agency predicts that an explosion of the magnitude of the 1980 eruption is unlikely. However, scientists from the U.S. Geological Survey Cascades Volcano Observatory and the Pacific Northwest Seismic Network carefully monitor seismic data, gas emissions, changes in the ground surface, and other factors around Mount St. Helens to forecast potential volcanic activity.

The 10 Best Air Fryers on Amazon


When it comes to making food that’s delicious, quick, and easy, you can’t go wrong with an air fryer. They require only a fraction of the oil that traditional fryers do, so you get that same delicious, crispy texture of the fried foods you love while avoiding the extra calories and fat you don’t.

But with so many air fryers out there, it can be tough to choose the one that’ll work best for you. To make your life easier—and get you closer to that tasty piece of fried chicken—we’ve put together a list of some of Amazon’s top-rated air frying gadgets. Each of the products below has at least a 4.5-star rating and over 1200 user reviews, so you can stop dreaming about the perfect dinner and start eating it instead.

1. Ultrean Air Fryer; $76


Around 84 percent of reviewers awarded the Ultrean Air Fryer five stars on Amazon, making it one of the most popular models on the site. This 4.2-quart oven doesn't just fry, either—it also grills, roasts, and bakes via its innovative rapid air technology heating system. It's available in four different colors (red, light blue, black, and white), making it the perfect accent piece for any kitchen.

Buy it: Amazon

2. Cosori Air Fryer; $120


This highly celebrated air fryer from Cosori will quickly become your favorite sous chef. With 11 one-touch presets for frying favorites, like bacon, veggies, and fries, you can take the guesswork out of cooking and let the Cosori do the work instead. One reviewer who “absolutely hates cooking” said, after using it, “I'm actually excited to cook for the first time ever.” You’ll feel the same way!

Buy it: Amazon

3. Innsky Air Fryer; $90


With its streamlined design and the ability to cook with little to no oil, the Innsky air fryer will make you feel like the picture of elegance as you chow down on a piece of fried shrimp. You can set a timer on the fryer so it starts cooking when you want it to, and it automatically shuts off when the cooking time is done (a great safety feature for chefs who get easily distracted).

Buy it: Amazon

4. Secura Air Fryer; $62


This air fryer from Secura uses a combination of heating techniques—hot air and high-speed air circulation—for fast and easy food prep. And, as one reviewer remarked, with an extra-large 4.2-quart basket “[it’s] good for feeding a crowd, which makes it a great option for large families.” This fryer even comes with a toaster rack and skewers, making it a great addition to a neighborhood barbecue or family glamping trip.

Buy it: Amazon

5. Chefman Turbo Fry; $60


For those of you really looking to cut back, the Chefman Turbo Fry uses 98 percent less oil than traditional fryers, according to the manufacturer. And with its two-in-one tank basket that allows you to cook multiple items at the same time, you can finally stop using so many pots and pans when you’re making dinner.

Buy it: Amazon

6. Ninja Air Fryer; $100


The Ninja Air Fryer is a multipurpose gadget that allows you to do far more than crisp up your favorite foods. This air fryer’s one-touch control panel lets you air fry, roast, reheat, or even dehydrate meats, fruits, and veggies, whether your ingredients are fresh or frozen. And the simple interface means that you're only a couple buttons away from a homemade dinner.

Buy it: Amazon

7. Instant Pot Air Fryer + Electronic Pressure Cooker; $180

Instant Pot/Amazon

Enjoy all the perks of an Instant Pot—the ability to serve as a pressure cooker, slow cooker, yogurt maker, and more—with a lid that turns the whole thing into an air fryer as well. The multi-level fryer basket has a broiling tray to ensure even crisping throughout, and it’s big enough to cook a meal for up to eight. If you’re more into a traditional air fryer, check out Instant Pot’s new Instant Vortex Pro ($140) air fryer, which gives you the ability to bake, proof, toast, and more.

Buy it: Amazon

8. Omorc Habor Air Fryer; $100

Omorc Habor/Amazon

With a 5.8-quart capacity, this air fryer from Omorc Habor is larger than most, giving you the flexibility of cooking dinner for two or a spread for a party. To give you a clearer picture of the size, its square fryer basket, built to maximize cooking capacity, can handle a five-pound chicken (or all the fries you could possibly eat). Plus, with a non-stick coating and dishwasher-safe basket and frying pot, this handy appliance practically cleans itself.

Buy it: Amazon

9. Dash Deluxe Air Fryer; $100


Dash’s air fryer might look retro, but its high-tech cooking ability is anything but. Its generously sized frying basket can fry up to two pounds of French fries or two dozen wings, and its cool touch handle makes it easy (and safe) to use. And if you're still stumped on what to actually cook once you get your Dash fryer, you'll get a free recipe guide in the box filled with tips and tricks to get the most out of your meal.

Buy it: Amazon

10. Bella Air Fryer; $52


This petite air fryer from Bella may be on the smaller side, but it still packs a powerful punch. Its 2.6-quart frying basket makes it an ideal choice for couples or smaller families—all you have to do is set the temperature and timer, and throw your food inside. Once the meal is ready, its indicator light will ding to let you know that it’s time to eat.

Buy it: Amazon

This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links.

Does Putting a Penny in the Microwave Really Make It Shrink?

J E Theriot, Flickr // CC BY 2.0
J E Theriot, Flickr // CC BY 2.0

It's a lesson even the worst home cooks (hopefully) know: Putting metal in the microwave is a recipe for disaster. Thanks to a viral image circulating on the web, some people may be tempted to ignore this piece of common sense in the name of experimentation. The picture shows one normal-sized penny next to three smaller pennies with the caption: "This is what happens when you put a penny in a microwave for 2 minutes." But according to Snopes, microwaving a penny won't cause it to shrink—if anything, it will just leave you with a broken microwave.

Microwave ovens heat food by bouncing microwaves around a metal box. Certain molecules, like the molecules in your leftovers, absorb these waves via dielectric loss and convert them into heat. Not all substances are compatible with microwaves, however. Metal contains high concentrations of electrons, and when microwaves hit a metallic surface, these electrons become very active and block the wave's path. Instead of absorbing into the metal, the microwaves bounce off, which can cause electrical sparks. Sometimes these sparks are strong enough to burn a hole in the oven's walls and damage the electronic equipment.

Even if you could somehow shrink coins in a microwave, the science explained above should be reason enough to resist the urge to try it at home. Anyone who tries the experiment against their better instincts will be disappointed. The photo that's been shared on social media is a hoax, with Snopes explaining that the smaller pennies likely originated in a magician's trick kit.

The post inspired some people to share false claims of their own. One response to the image showed a melted microwave that had allegedly fallen victim to the penny trick. In reality, the years-old picture came from a blogger who set their microwave on fire accidentally while heating a pot of oil. So while microwaving a penny may cause some sparks and potentially damage your appliance, a dramatic explosion isn't likely. (Please just take our word on that, too.)

[h/t Snopes]