6 volcanoes that could shut down the world

Scientists are predicting the eruption of the Axial Seamount, an underwater volcano off the Pacific coast of the U.S., because it is showing similar signs to its previous eruption in 2015. While it poses little threat to humans, this potential eruption could help with improving tracking methods for other, more dangerous, volcanoes, and will come in handy as warming temperatures continue to affect the planet.

Climate change is causing ice melt, which may also encourage the eruptions of more than 100 volcanoes located in Antarctica. The "unloading of ice sheets reduces pressure on magma chambers below the surface, causing the compressed magma to expand," said LiveScience. "This expansion increases pressure on magma chamber walls and can lead to eruptions." While this process may take hundreds of years, "heat from these eruptions can increase ice melting deep below the surface and weaken the overlying ice sheet — potentially leading to a feedback loop of reduced pressure from the surface and further volcanic eruptions."

Although none of these events are immediate threats, volcanic activity can be massively dangerous — and in some cases, catastrophic. Scientists have been monitoring several supervolcanoes that have the potential to cause widespread or even apocalyptic damage.

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1. Askja (Iceland)

Last eruption: 1961

Effects of a major eruption: Askja volcano has been showing some signs of an impending eruption and it "could be catastrophic," said Reuters. Iceland is a hotbed of volcanic activity and scientists predict that more eruptions will occur because of climate change melting the glaciers. In addition, 160 million people live within 100 km (62 miles) of a volcano in the country. While Askja’s 1961 eruption was milder, it also erupted in 1875, and that "eruption produced a large amount of tephra (volcanic ash and fragments)," said Perlan. "The ash from the eruption was dispersed widely, covering large parts of eastern and northern Iceland. The ash layer was so thick in some places that it caused darkness during daylight hours." The ash also led to widespread food shortages, leading to mass emigration from Iceland, and released high levels of carbon dioxide that were felt globally.

Likelihood: "There's so much uncertainty on when this will erupt — if it will erupt," Michelle Parks, a volcanologist with the Icelandic Meteorological Office, said to Reuters. It could be years or decades or even sooner. The country is preparing for the possibility of severe volcanic eruptions.

2. Cumbre Vieja (La Palma, Canary Islands)

Last eruption: 2021

Effects of a major eruption: When Cumbre Vieja last erupted in 2021, "lava poured out of the volcanic ridge, and flowed to the sea, engulfing 3000+ dwellings, said NASA's Jet Propulsion Laboratory. While thousands of people were evacuated, the damage from the eruption was not as severe as it could have been. Scientists had warned that a major eruption of Cumbre Vieja could cause the entire western flank of the volcano to fall into the sea, creating a "mega-tsunami" wherein "waves hundreds of meters high" would radiate "out into the Atlantic," the New Zealand Herald said. However, subsequent studies of the "potential consequences of a collapse at Cumbre Vieja have significantly downplayed the risk" of such an outcome. In a 2021 report for the U.S. Geological Survey, the Hawaiian Volcano Observatory said that the theory of an eruption-prompted mega-tsunami "does not hold up to rigorous examination."

Likelihood: Scientists say the "year to year probability" of a major eruption is low, but preparations should be taken anyway given the potentially cataclysmic damages.

3. Mount St. Helens (Washington, United States)

Last eruption: 1980

Effects of major eruption: Mount St. Helens' eruption in May 1980 resulted in 57 deaths and caused the "largest landslide in recorded history," said NASA. In addition, "hot pressurized magma erupted, and the ash plume reached a towering height of 80,000 feet (15 miles, 24 km), before blanketing the surrounding region," said EarthSky. Everything within approximately 230 square miles was destroyed and required extensive recovery. "In the decades since the eruption, Mt. St. Helens has given scientists an unprecedented opportunity to witness the intricate steps through which life reclaims a devastated landscape," NASA added.

Likelihood: While Mount St. Helens is expected to erupt again in our lifetimes, "neither a large debris avalanche nor a major lateral blast like those of May 18, 1980 is likely now that a deep crater has formed," said the U.S. Geological Survey.

4. Mt. Vesuvius (Italy)

Last eruption: 1944

Effects of major eruption: Famous for wiping out Pompeii and Herculaneum in 79 A.D., Vesuvius would do much greater damage if it erupted again today. "Given its potential, Vesuvius could endanger more than 3 million people and wipe out the city of Naples," said HowStuffWorks. The region also has a "'squatter' dilemma, with over 700,000 people residing illegally on its slopes," at risk. Vesuvius's next eruption will likely be an "incredibly forceful explosion … marked by flying rock and ash at speeds of up to almost 100 miles per hour."

Likelihood: Luckily, scientists say Vesuvius likely won't have a major eruption again for a few hundred years.

5. Popocatépetl (Mexico)

Last eruption: Ongoing since the early 2000s

Effects of a major eruption: The third-tallest active volcano in the Northern Hemisphere, Popocatépetl is only 40 miles west of Mexico City, whose metropolitan area has an estimated 22 million inhabitants, and just 30 miles east of Puebla, a city of around six million. A large eruption could send "a city-sized cloud of ash 20 centimeters thick" to "descend upon the buildings of Mexico City," Pacific Standard said. The deadly cloud would then "clog Mexico City's drainage lines, poisoning its water supplies and ceasing electricity transmission via short-circuiting," and the devastation would be accompanied by "1,000-degree lahars and pyroclastic flows" that would reach most of the towns in the immediate area.

Likelihood: After an 80-year dormant period, Popocatépetl has had recurring seismic activity for years, with 13 eruptions occurring as recently as February 2024. While small explosions have caused alarm, "after nearby towns were coated in ash," The Associated Press said, "volcanologists called the activity 'nothing new or surprising.'"

6. Yellowstone Supervolcano (Wyoming, United States)

Last eruption: 640,000 years ago

Effects of a major eruption: When the Yellowstone Caldera, or "supervolcano," in Yellowstone National Park erupts again, "its effects would be worldwide," the U.S. Geographical Survey said. In the U.S., the closest states to Yellowstone, including Montana, Idaho and Wyoming, could be "affected by destructive pyroclastic flows, which are a mix of lava blocks, pumice, ash and volcanic gas that flows around a volcano after an eruption," said The Hill. "Much of the rest of the country could be blanketed in falling volcanic ash — in some places, it could be more than three feet deep." Globally, the volcano could also "impact the global climate by emitting ash and gas into the stratosphere, which could block sunlight and lower global temperatures for a few years," Michael Poland from the Yellowstone Volcano Observatory said to LiveScience. The resulting catastrophe could "shut down transportation, collapse buildings, short-out the electrical grid and cause massive agricultural failure," the University of British Columbia's Johan Gilchrist said to CBC Radio.

Likelihood: While there is a lot of anticipation, "scientists revealed that Yellowstone National Park likely won't experience a supervolcano eruption within the same timeframe they once believed," as new research has found less concentrated magma than previously thought, said VICE.