Buzz
Experts often use complex terminology that can be hard to grasp.
While news outlets provide coverage, they can sometimes unintentionally spread inaccuracies. Journalists are not always able to delve into the fine details of science during a crisis.
It’s up to us to uncover the facts. As you go through this list, you might be surprised by how much you thought you knew!
People are captivated by volcanoes from a safe distance, and sometimes even when they pose a threat. That raw, fiery power is simply mesmerizing.
We’re just as curious. How do volcanic eruptions take place? Is it safe to ascend a volcano? What exactly are supervolcanoes?
10. Misconception: Molten rock drives eruptions
Around 25-30 kilometers (15-20 miles) beneath the surface, extreme heat and pressure exist. Certain types of rock melt under these conditions, creating magma.
This molten rock is buoyant enough to rise toward the surface through fissures in the overlying crust. It might not always make it, but if it does, an eruption occurs.
The journey is long, though. Doesn't the weight of the rock above help push the magma upwards?
Actually, it's powered by gas — not fossil fuel, but gases dissolved in the molten rock. These include water vapor, carbon dioxide, and sulfur dioxide.
As the magma rises, gases start to bubble out due to decreasing pressure as the rock above becomes thinner. This is similar to opening a carbonated drink bottle: the liquid is under pressure, but once the seal is broken, carbon dioxide bubbles form.
However, our magma pathway is still sealed, so the gases have no place to go except into the conduit. This accelerates the magma’s ascent, setting off a chain reaction that could result in an eruption—if the gases don’t deplete and the magma doesn’t hit an insurmountable barrier.
If the process halts, the magma will begin to cool and eventually solidify into formations like a dike, sill, or pluton. Erosion can sometimes expose these structures, showcasing their stunning beauty in places like Devil’s Tower in Wyoming.
9. Common Myth: Lava always erupts in flows
What’s often overlooked is the other side of the story: lava can also explode. We’re usually too busy running for safety or marveling at it from a distance to realize that this too is lava in action.
This phenomenon depends on the gases discussed earlier, along with the temperature and viscosity of the rising magma.
Temperature is simple. Molten rock behaves similarly to molasses, slowing down as it cools.
Viscosity is easy to grasp as well. Water has low viscosity, while asphalt is much thicker and more viscous.
In water, gases easily escape, while asphalt traps them. This is crucial since gases are what drive the rising magma.
It also contains silica, which tends to form long molecular chains, making the magma more viscous.
So, what’s the outcome of all this geochemistry?
Low-silica magma allows most of the gas to escape before an eruption, leaving just enough to fuel either a stunning Hawaiian-style lava flow or, if there’s a significant amount of silica, something more explosive like the clip above.
On the other hand, high-viscosity, high-silica magma traps more of its gases, increasing the internal pressure. This is similar to what happens when you shake a champagne bottle.
In both cases, the gas has nowhere to go until you pop the cork or the volcanic rock gives way. Then, BOOM!
Now you have a sports team covered in champagne and a countryside blanketed in broken lava, respectively.
8. Common Myth: Volcanoes erupt smoke
In reality, the solid material in that dramatic plume consists of rock and natural glass.
Don’t believe it? Just ask Mexico’s Popocatépetl Volcano.
During this year’s devastating wildfire season in both hemispheres, we’ve witnessed plumes from major fires that certainly appeared volcanic. However, there’s a significant difference in their composition.
Volcanic ash isn’t light and fluffy like the ash from bushfires. Instead, it’s made up of tiny, sharp fragments of rock and natural glass that can find their way into your lungs and even behind your contact lenses.
It’s heavy, too.
According to the US Geological Survey, just 4 inches of ash can weigh between 120-200 pounds per square yard. Even small amounts of volcanic ash can overwhelm and collapse a roof.
It can also wreak havoc on your home electronics and cause power outages, as volcanic ash is conductive to electricity.
Volcanic ash damages vehicles and other machinery. You’ll never see smoke causing this kind of impact on jet engines!
This is why there are Volcanic Ash Advisory Centers (VAAC) around the world, constantly monitoring ash clouds in global flight paths.
7. Common Myth: Lava and pyroclastic flows are the deadliest hazards at volcanoes
While pyroclastic flows are undeniably deadly, lava flows aren’t nearly as lethal.
Lava typically moves slow enough for you to avoid it. However, there are exceptions, so don’t get too confident the next time you visit an active volcano. Still, a study covering volcanic fatalities from 1500 AD to 2017 found that fewer than 700 people were killed by lava.
Pyroclastic flows, which are much faster and travel farther than lava, have claimed nearly 60,000 lives. What could possibly rival that?
Would you believe mud?
When water mixes with volcanic ash, it forms a dense slurry, resembling wet concrete, that rushes down river channels faster than people can escape.
Volcanologists refer to these mudflows by their Indonesian name: lahar. You definitely don’t want to get stuck in one of those.
Lahars can occur even without an eruption. All you need is water and loose ash. Heavy rainfall and tropical storms are infamous for triggering secondary lahars.
In the 2007 video above, the water came from a crater lake at New Zealand’s Mount Ruapehu:
Over the past five centuries, volcanic mudflows in various forms have claimed nearly 60,000 lives. They are just as deadly as pyroclastic flows!
6. Misconception: Lakes are immune to eruptions
We all marvel at volcanic eruptions at sea. Volcanoes near bodies of water can also trigger tsunamis, such as the 2018 eruption at Anak Krakatau in Indonesia, which claimed 400 lives.
However, most of us wouldn’t expect water to erupt on its own. But lake eruptions do occur, often with a volcano lurking somewhere nearby.
The volcano’s gases seep through the lake bed into the water. Under certain conditions (explained below), they can accumulate until the lake erupts, releasing all that gas in a catastrophic explosion.
Lake Kivu, mentioned in the video above, lies at the base of Mount Nyiragongo in the Democratic Republic of the Congo.
Researchers are concerned that volcanic eruptions could occur directly beneath the city of Goma, located by Lake Kivu. This would already be catastrophic, but it could also trigger a lake eruption, causing a double disaster.
But why would lava erupt in a town situated 14 kilometers (9 miles) away from the volcano?
5. Misconception: Eruptions always begin at the summit of a volcano
Just ask Mount St. Helens, which erupted sideways in 1980 after a landslide removed the rocks covering the magma inside the mountain!
Active volcanoes typically have at least one summit crater, but molten rock will seek out any weakness it encounters.
In 1977 and again in 2002, for instance, Mount Nyiragongo’s well-known lava lake spilled through significant cracks in the surrounding rocky walls. These unexpected eruptions occurred down the slopes, near villages, and tragically, many lives were lost.
Volcanic fissures typically form a network and can be quite widespread. One such system stretches from Nyiragongo’s peak all the way to Goma, the provincial capital, which sits by the potentially dangerous Lake Kivu.
Although no activity has been recorded there in history, it’s entirely possible that these fissures could cause a future eruption. And as we've seen, that could lead to a double disaster if it triggers an eruption in the lake as well.
On a brighter note, stunning Iceland is filled with fissures, as it sits on an area where two tectonic plates are slowly drifting apart.
Fissure eruptions are common here. The most recent one, at Bardarbunga Volcano in 2014, didn’t significantly affect North Atlantic air traffic, but it was still quite a show.
In this drone video, it might seem as if the lava is coming from a crater, but it's actually a spatter rampart, where cooled blobs from the lava fountains accumulate.
4. Misconception: Exclusion zones are merely recommendations, not actual rules.
If scientists can go there, why can’t we?
Because the dangers of a volcano are often hidden, and what you don’t know can kill you. This is true even for the experts.
In 1993, an international team of volcanologists ventured into the crater of Colombia’s Galeras Volcano, which had been dormant for five months, to gather data for the Decade Volcano program.
They were aware of the risks and prepared to evacuate at any moment if other scientists, monitoring the volcano’s real-time data from a nearby observatory, detected the slightest hint of danger.
However, Galeras erupted without warning, killing six volcanologists and three local residents who had come to observe the research.
Such sudden changes are inevitable when a mountain-sized pressure cooker is sitting on a hot burner, even in areas considered ‘safe’.
Exclusion zones are grounded in common sense, drawn from hard-earned experience and the tragic loss of nearly seventy scientists and hundreds of thousands of other lives.
The tragic eruption at White Island/Whakaari Volcano in December 2019, despite its loss, led to new advancements in volcanology.
Occasionally, a scientist will take risks, hoping that their actions will save countless lives in the future.
But what about you? Is snapping a selfie, gaining bragging rights, or admiring the view truly worth stepping into a restricted area and possibly becoming just another statistic on someone else’s research graph?
3. Misconception: A supervolcano eruption spells the end of the world.
Although we still know very little about supereruptions, it’s undeniable that the global impact of one would be catastrophic.
That being said, there's no need for widespread panic if the Yellowstone Volcano Observatory, or any similar organization for other supervolcanoes, issues a warning.
Smaller eruptions are also possible. Experts predict that Yellowstone's next major event is more likely to be a hydrothermal blast (a steam eruption capable of throwing rocks) or a lava flow.
Hydrothermal explosions are fairly frequent at Yellowstone, occurring every two to three years. Larger explosions, which form craters that can span several hundred meters, happen once every few thousand years.
Since its last VEI 8 eruption around 630,000 years ago, Yellowstone has experienced eighty recorded lava flows, with the most recent one about 70,000 years ago. These nonexplosive events wouldn't significantly affect areas outside of Yellowstone Park.
Can scientists studying Yellowstone determine whether an upcoming eruption will be small or massive? Yes, they most likely can.
Given the massive volume of magma involved, a supereruption will almost certainly be preceded by noticeable signs — shifts in seismic activity, ground deformation, changes in chemistry, and other indicators that suggest an impending volcanic event.
Even if a supereruption were to occur, it might not necessarily lead to the extinction of life. However, something far beyond the current VEI scale would indeed be a major concern.
2. Misconception: Supereruptions are comparable to nuclear explosions
What's harder to grasp: the fact that a supereruption can expel at least 1,000 km3 (240 cu mi) of material, or simply allowing filmmakers and game designers to envision it for us?
Naturally, we rely on simulations. Given the scale of such events is beyond our real-world experience, special effects creators often take a nuclear approach to visualizing them.
While some efforts try to stay grounded in scientific facts, very little is truly known about supereruptions. What is clear is that at least two other massive calderas in the US, aside from Yellowstone, have erupted in the past two million years, as well as others in New Zealand, Indonesia, Japan, and South America.
Of these eruptions, Taupo in New Zealand experienced the most recent supereruption around 23,000 years ago, while Indonesia's Toba eruption 74,000 years ago was the largest.
Present-day scientific theories for the occurrence of supereruptions include the following:
1. “Unzipping”: This theory proposes that multiple Plinian eruptions occur along massive ring fractures in the Earth's crust, emptying the magma chamber beneath and causing it to collapse, thus forming a caldera. This may have been the case at California’s Long Valley Caldera.
2. “Boiling over”: In some supervolcanoes, like Cerro Galan in Argentina, there is no evidence of Plinian eruptions. Instead, dense clouds of crystalline magma may have poured out of the forming caldera, too heavy to rise high.
We may never fully understand how supereruptions occur until one happens. Let's just hope we make it out alive!
1. Misconception: Every massive eruption is Plinian
For most people, any explosive volcanic event seems awe-inspiring. They must be Plinian, right? And the other type would be those calm Hawaiian-style lava flows and fountains?
In fact, the Volcanic Explosivity Index (VEI) begins at VEI 0 for Hawaiian eruptions and escalates all the way to VEI 8, which represents a supereruption.
Between these extremes, there are various intermediate categories, including four distinct types of Plinian eruptions.
They say a picture speaks a thousand words, so let’s take a look at two dramatic volcanic eruptions.
The footage above shows Taal Volcano erupting in January 2020, a truly intense and terrifying event.
It doesn’t have a VEI rating yet, but Philippine volcanologists describe this eruption as steam-driven (“phreatomagmatic”).
In terms of power, though, it doesn’t even come close to a Plinian eruption.
While the eruption could certainly be compared to the Mount Vesuvius eruption of 79 AD that destroyed Pompeii, scientists tend to be particular when it comes to specifics.
Some refer to this as “classic Plinian,” while others categorize it as subplinian.
The VEI scale provides geoscientists with a shared framework for resolving nuanced debates like this one. For instance,
• VEI 4 is “Pelean/Plinian”; think Eyjafjallajokul, the Icelandic volcano that disrupted air traffic in 2010. • VEI 5 is “Plinian”; Mount St. Helens, 1980. • VEI 6 is “Plinian/Ultraplinian”; Pinatubo, 1991. • VEI 7 is “Ultraplinian”; Tambora’s enormous eruption in the nineteenth century.
Fortunately, humanity hasn’t witnessed a VEI 8 eruption in recorded history. But what would that look like?
+ Misconception: Supervolcanoes represent the largest eruptions ever recorded
Don’t panic, but approximately every twenty million years, the earth's surface cracks open, unleashing millions of cubic kilometers of molten rock that either flow or erupt explosively across the land for spans of 1-5 million years.
The key word here is “millions,” which is why there's no need to panic.
The most recent occurrence of this event took place about 15 million years ago in the Pacific Northwest. Geologists refer to this large igneous province (LIP) as the Columbia River Basalts, whose distinctive rocks now form the stunning cliffs of the Columbia River Gorge.
That means we have at least another 5 million years to go before the next one.
LIPs represent cutting-edge scientific research that delves far beyond the scope of this article.
It’s pretty fun to know that geoscientists actually have a 'LIP of the Month' web page. It’s a really cool feature, even if (like most of us) you don’t have a PhD.
It’s also fascinating to realize that volcanologists have linked some of these ancient events to modern volcanoes—such as connecting Yellowstone to the Columbia River Basalts LIP, and the rare volcanic islands of Heard and McDonald in Australia to the mostly submerged Kerguelen Plateau LIP.
Don’t worry. These places aren’t going to suddenly wake up. They’re merely the final flickers of a once fierce fire across the land.
While Yellowstone continues to require monitoring, Heard Island is already covered by a thick layer of snow and ice.
