On May 18, 1980, Mount St. Helens erupted — it was the “deadliest and most economically destructive volcanic event in the history of the United States,” according to the National Oceanic and Atmospheric Administration, generating “about 500 times the force that the atomic bomb dropped on Hiroshima,” it killed 57 people and thousands of animals and lopped 1,300 feet off the top of the mountain.

Still, there’s another volcano that is much more concerning to volcanologists. On this episode of America’s National Parks, Washington’s Mount Rainier National Park, and its namesake volcano’s potential for mass destruction.


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Learn More

Links to some of the resources we used and the website links we mentioned in this episode. 

Mount Rainier National Park – National Park Service Website

This May Be the Most Dangerous US Volcano – National Geographic

That Fissure Opening “Near” Yellowstone? Not a Sign of an Impending Eruption. – Discover

Mount St. Helens and the Worst Volcano Eruption in U.S. History – Time

The historic inns at Rainier – Rainier Guest Services


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About a month ago a large fissure opened up in the wall of a cliff face at Grand Tetons National Park. A fissure is a separation in rock caused by geological movement and is a fairly normal occurrence. The park closed off the surrounding area because loose rock can dangerously tumble for extended periods after a fissure opens up. Again…this was a totally normal occurrence.

But you can’t tell that to a conspiracy theorist.

Grand Tetons National Park neighbors Yellowstone National Park, full of all its wonderful, dramatic geothermal features. All of that bubbling and gurgling and spraying is caused by a plume of molten rock that rises beneath the surface – a Supervolcano.

The first major eruption of the Yellowstone volcano occurred 2.1 million years ago, and it’s one of the largest volcanic eruptions we know of, covering over 5,790 square miles with ash. So if you do a quick google search for the Yellowstone Supervolcano, you’re going to find some pretty terrifying theories about what will happen when the Northwest corner of Wyoming erupts again.

What’s more, you’ll find a heck of a lot of articles, and youtube videos, in particular, about how the government is keeping the signs of an impending eruption secret. They’ll point to the changes in Old Faithful’s predictability, increased earthquakes, and other totally normal geothermic occurances that they can make sound uncommon.

So it was no surprise that, when that fissure opened up 60 miles from the Yellowstone caldera in the Tetons, the conspiracy theory machine kicked into hyperdrive:

[Youtube clip montage]

The government, of course, is hiding all of this from you for some reason.

Unfortunately, this completely normal occurrence was also picked up by some more mainstream media. Especially in the UK, where the Daily Mail headline read: “Rock fissure sparks URGENT closure at Grand Teton National Park, just 60 miles from Yellowstone supervolcano.” “Urgent is in all caps. It’s accompanied by a scary map showing waist high ash covering the country as far as Chicago and Los Angeles. Epcot could be blanketed in as much as 3 inches. In the Daily Express: “Yellowstone Volcano latest: 100-FOOT fissure sparks URGENT park closure“ — “Urgent” again in all caps — and after an explanation from park officials the article went off on its own tangent — I’m quoting here:

“If the Wyoming volcano were to erupt an estimated 87,000 people would be killed immediately and two-thirds of the USA would immediately be made uninhabitable. The large spew of ash into the atmosphere would block out sunlight and directly affect life beneath it creating a ‘nuclear winter.’ The massive eruption could be a staggering 6,000 times as powerful as the one from Washington’s Mount St Helens in 1980.

End quote.

The reality is that the most recent major eruption was 640,000 years ago, and it was on nowhere near that scale. Since then, 80 smaller eruptions have occurred, most recently 70,000 years ago, partially filling the caldera. A cataclysmic eruption is highly unlikely in the foreseeable future. If an eruption were to happen, what we’re more likely to see is some smaller lava flows, similar to the most recent eruptions in Hawaii. And just to be safe, monitoring of all sorts of volcanic eruption indicators is constantly underway at Yellowstone. Worrying about the “big one” isn’t too dissimilar from worrying about an asteroid crashing into the planet. There’s nothing you can do, so why bother?

There are 169 active volcanoes in the United States, most of those are in Alaska, and Yellowstone doesn’t even break the top ten of the ones that scientists consider the most dangerous. On May 18, 1980, Mount St. Helens erupted — it was the “deadliest and most economically destructive volcanic event in the history of the United States,” according to the National Oceanic and Atmospheric Administration, generating “about 500 times the force that the atomic bomb dropped on Hiroshima,” it killed 57 people and thousands of animals and lopped 1,300 feet off the top of the mountain.

Still, there’s another volcano that is much more concerning to volcanologists. On this episode of America’s National Parks, Washington’s Mount Rainier National Park, and its namesake volcano’s potential for mass destruction.

The picturesque wonder of Mount Rainier looms in the background of most postcard photos of the Seattle skyline, like God’s reminder of the trivial accomplishments of man. What does the Space Needle have on a 14,000-foot volcano?

The 3.7 million people of the largest metropolitan area in the Pacific Northwest go about their days, generally without a thought of the danger that lurks to the southeast.

“Mount Rainier is one of the most dangerous volcanoes in the world,” Volcanologist Janine Krippner told National Geographic. A significant eruption of Mount Rainier could result in one of the worst natural disasters in US history.

To understand why you only need look at the icy cloak that Rainier wears. Over 35 square miles of permanent ice and snow cover it. Of all the glaciers in the contiguous U.S., Mount Rainier’s Emmons Glacier has the largest surface area. Carbon Glacier is the longest, and the thickest at 700 feet deep.

What happens to that ice under a major volcanic eruption is worse than the layperson can imagine. For an analogous event, Krippner pointed to the story of Colombia’s Nevado del Ruiz volcano which erupted 33 years ago.

Beginning in November 1984, geologists observed an increasing level of seismic activity near Nevado del Ruiz, as well as increased fumarole activity, deposits of sulfur on the summit, and small explosions where magma came in contact with water, instantly turned it into steam.

A year later, volcanic activity once again increased as magma neared the surface. The volcano began releasing gases and the springs in the vicinity became enriched in magnesium, calcium, and potassium, leached from the magma. The gas releases caused pressure to build up inside the volcano, which eventually resulted in the explosive eruption.

At 3:06 pm, on November 13, 1985, more than 35 million tons of material ejected 19 miles into the atmosphere. That may sound like a lot, but it’s only about 3% of that of the Mount Saint Helens eruption.

Pyroclastic flows — or fast-moving streams of gas and molten rock — began to melt the summit glaciers and snow, and the water mixed with rocks and clay as it traveled down the volcano’s flanks, in four thick flows — like rivers of uncured concrete. It’s a phenomenon known as a lahar.

The violent lahar mudflows ran down the volcano’s sides at nearly 40 miles per hour, breaking off more rock and soil and vegetation in their path. At the base of the volcano, the lahars were directed into all of the six river valleys, which grew to almost 4 times their original volume.

One of the lahars swallowed a town nearly whole. One-quarter of its 29,000 inhabitants survived. Another killed 1,800 people and destroyed 400 homes. In total, over 23,000 people were killed, and approximately 5,000 were injured in the eruption, and more than 5,000 homes were destroyed. It’s the deadliest volcanic disaster in the last 100 years and the fourth-deadliest eruption in recorded history.

Since the volcano’s last substantial eruption occurred more than 140 years earlier, it was hard for many to accept the danger the volcano presented, even though it was known that an eruption was highly possible due to the increased activity the year prior. Maps showing completely flooded areas in the case of an eruption were distributed more than a month before the eruption, but the Colombian Congress criticized the scientific and civil defense agencies for scaremongering. The town of Armero’s mayor and religious authorities kept residents calm after the initial eruption, and then a storm hit that evening, causing electrical outages and hindering communications. The lahars hit the town of Armero at about 30 miles an hour as its residents slept.

At Rainier, The US Geological Survey has mapped and studied the sleeping volcano, and it’s clear that lahars are an extreme danger. At least 60 lahars have dramatically altered various portions of Mount Rainier during the past 10,000 years.

“Lahars can lift houses. They can overtake a bridge. They can take the bridge with it,” Krippner said. There’s evidence that in the past, lahars filled Rainier’s valleys to heights of almost 500 feet. “Imagine if you’re in that valley today,” Krippner said, asking if you could climb to that hight faster than a 40 mile per hour mudflow.

At least 80,000 people sit in zones that lahars are capable of reaching. But are those people prepared?

Rainier’s glaciers and proximity to large amounts of people led to its inclusion as one of the sixteen volcanoes worldwide studied through the United Nations Decade Initiative aimed at leveraging a partnership between science and emergency management to reduce the severity of natural disasters. In 1992, a plan was developed through the National Academy of Sciences for researching the hazards and risks connected with Mount Rainier. The US Geological Survey has an extensive strategy to communicate warnings and aid authorities, but many people remain blissfully unaware of the real dangers Rainier represents. That’s compounded by the popularity of the Pacific Northwest in recent years.

Rainier last threatened to blow in 1895, when minor explosions shook the summit, but it hasn’t significantly erupted for a thousand years or so. Still, a cataclysmic eruption isn’t required for a lahar. In 1947, massive amounts of water discharged from a Rainier Glacier, channeling a one-mile canyon in the ice. The resulting mudflow moved 50 million cubic yards of debris, drastically changing the topography of the area. Several smaller debris flows followed.

Rainier is one of the most monitored volcanoes on the planet, but the next eruption or lahar could come with little to no warning. Evacuation routes are in place, but it’s unlikely that it will be possible to evacuate thousands of people in minutes. If they even listen to the warning. It’s often assumed that in the face of a disaster, people panic. History tells us that they’re more likely to shrug off a warning.


It’s not lost on me that we started this episode of belittling conspiracy theorists and fear-mongerers, and then gave you a terrifying story. The Danger at Rainier is real, but it shouldn’t stop anyone from visiting or living there. Preparation is the key to surviving any disaster. The local municipalities and science communities are doing everything they can to help keep people safe. They’re learning how lakes upstream of dams on the lahar paths can be drained to stop them cold. They’re creating information campaigns and awareness plans. And hopefully, we will have warning of an imminent eruption, and when we do, people will heed it.

Mount Rainier is one of the oldest national parks, and one of the most visited. The park is famous for its wildflowers, and is home to a vast array of Pacific Northwest wildlife, including Mountain Lion, Bobcat, Red Fox, Coyote, Black Bear, Deer, Elk, Mountain Goats, Porcupine, Marmots, and Beaver. And, of course, if you’re a mountaineer, you can attempt to summit the 14,410-foot active volcano. Reaching the summit requires a vertical elevation gain of more than 9,000 feet over a distance of eight or more miles.

On weekend days in the summer, parking lots can fill by mid-morning. Try to visit on weekdays, or arriving in the early morning or late afternoon when people begin to leave.

The weather is generally cool and rainy even during the peak of the summer. Visitors should always bring rain gear. Backcountry camping is allowed with a permit, and the park has four campgrounds open during the summer months, three of which can accommodate RVs. There are also established campsites along many trails. All require reservations.

There are two inns located inside the park, the National Park Inn, located in the Longmire district is open year-round, and the historic Paradise Inn, Designated as one of the “Great Lodges of the West,” sits at an elevation of 5,420 feet, with hiking trails just outside the door. Here you’ll find no televisions, telephones, or Internet, just the tranquility of nature.

At an elevation of 6,400 feet, the Sunrise area is the highest point that can be reached by vehicle. In summer, mountain meadows team with wildflowers. Sunrise Point offers nearly 360-degree views of the surrounding valleys, Mount Rainier, and other volcanoes in the Cascade Range such as Mount Adams.

The Paradise area is also famous for its wildflower meadows and stunning views. The park’s main visitor center is here, and it’s the prime winter-use area in the park, receiving on average 643 inches of snow a year. Winter activities include snowshoeing, cross-country skiing and tubing. The road between Longmire and Paradise is plowed throughout the winter.

This episode of America’s National Parks was written by me, Jason Epperson, and narrated by Abigail Trabue. If you enjoyed the show, we’d love a 5-star review wherever you listen to podcasts. Don’t forget to subscribe, and follow us on Facebook, Twitter, and Instagram. Just search “National Park Podcast.” You can also join our new America’s National Parks Facebook group. We’ll link to all of our social media, as well as National Park Service resources, music credits, and more in the show notes at National Park Podcast dot com.

If you are interested in RV travel, give us a listen over at the RV Miles Podcast. You can also follow Abigail and I as we travel the country in our converted school bus with our three boys at Our Wandering Family dot com.

Today’s show was sponsored by L.L.Bean, follow the hashtag #beanoutsider, and visit LLBean.com to find great gear for exploring the National Parks.


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