Hawaii's Mauna Loa volcano awakened from its slumber, erupting for the first time in nearly 40 years. The largest active volcano on Earth, the U.S. Geological Survey listed Mauna Loa at a red/warning level, and said numerous lava flows were visible near the summit. While this particular eruption seems to be contained, other volcanoes around the world could pose more danger, should they flare up. Nature reported that a massive eruption could have devastating effects "across transport, food, water, trade, energy, finance, and communication in our globally connected world." An event of this scale "would be abrupt and immense, with uneven effects on weather, rainfall, and temperature," Nature added. Here are six other volcanoes worth fearing:
1. Katla (Iceland)
Last eruption: 1918
Effects of a major eruption: If Katla goes off, its eruption will be 10 times stronger than nearby Eyjafjallajokull, which exploded in 2010, causing billions of dollars in economic damage and leaving millions of travelers stranded. Katla's larger ash plume would shoot higher in the air and spread over larger areas of Europe for a longer period, with much more devastating effects on air travel and economic trade. An eruption could tip Europe's economy — perhaps even the world's — back into severe recession or a depression.
Likelihood: Fairly high. The two volcanoes, only 12 miles apart, tend to erupt in tandem, and Katla is slightly overdue in its 80-year cycle.
2. Cumbre Vieja (La Palma, Canary Islands)
Last eruption: 1971
Effects of a major eruption: In 2001, U.S. and British scientists 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" in the Atlantic. Traveling at 500 miles per hour, it would wipe out Florida, coastal Brazil, and parts of Europe with waves up to 160-feet high.
Likelihood: The 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. 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 today. About 3 million people live near the volcano, 600,000 of them in the "red zone." An eruption would kill at least 8,000 people and cause more than $24 billion worth of damage, according to Willis Research Network, which just named Vesuvius the most dangerous volcano in Europe. The ash would change weather patterns in Europe and leave the Naples area a "lifeless desert."
Likelihood: Scientists say Vesuvius is overdue for an explosion.
4. Popocatépetl (Mexico)
Last eruption: Ongoing since 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 and its 18 million inhabitants, and 30 miles east of Puebla, a city of two million. A large eruption could send deadly mudslides into the populous valleys below, creating "catastrophic" loss of life.
Likelihood: After an 80-year dormant period, Popocatépetl has had recurring seismic activity for years, with two explosions occurring as recently as Sept. 2022.
5. Mt. Tambora (Sumbawa, Indonesia)
Last eruption: 1967
Effects of a major eruption: Tambora erupted in spectacular fashion in 1815 and changed weather patterns around the globe, causing "frosts in Italy in June and snows in Virginia in July, and the failure of crops in immense swaths across Europe and the Americas." The blow-up killed more than 71,000 people directly, and many more through famine and sickness.
Likelihood: Tambora is still active and, given its history and Indonesia's 222 million inhabitants, closely monitored.
6. Yellowstone Supervolcano (United States)
Last eruption: 640,000 years ago
Effects of a major eruption: When the Yellowstone Caldera, or "supervolcano," in Yellowstone National erupts again, it will render a huge swath of North America, from Vancouver to Oklahoma City, uninhabitable. It would have incalculable human and economic consequences. The last eruption of similar magnitude — 73,000 years ago in Sumatra — plunged the entire planet into a decade-long volcanic winter and nearly wiped out the human race.
Likelihood: Geologists see signs that it could be preparing for another major blowout soon, although "soon" could mean thousands of years from now.
Update Nov. 28, 2022: This article has been updated with information regarding the Mauna Loa eruption.