16 Thrilling Facts About Volcanoes

Volcanoes offer a glimpse into the Earth's fiery core, but their power can be perilous. Even smaller eruptions can have significant global consequences. Here are some fascinating facts about volcanoes.

1. The Volcanic Explosivity Index (VEI) gauges the strength and magnitude of volcanic eruptions.

Developed in 1982 by Chris Newhall from the United States Geological Survey and Stephen Self from the University of Hawaii, the VEI assesses volcanic eruption intensity by measuring the volume of materials like volcanic ash, tephra (rock and lava fragments), pyroclastic flows (rapidly moving gas and tephra), and other debris. The eruption's height and duration are also taken into account. The scale ranges from 1 to 8, with each increment representing a tenfold increase in ejecta. Thankfully, there hasn’t been a VEI-8 eruption in the past 10,000 years.

2. Wah Wah Springs may sound charming, but it was actually the site of a prehistoric supervolcano.

Around 30 million years ago, one of the most massive eruptions in history occurred in what is now eastern Nevada and western Utah. A supervolcano released 3500 cubic kilometers of magma across an area of roughly 12,000 square miles. The eruption deposited debris 13,000 feet deep. To put it into perspective, the 1883 eruption of Krakatau in Indonesia was heard across vast distances, yet it was a minor event compared to Wah Wah Springs, a VEI-8 eruption.

3. When dealing with volcanoes, lava isn't the most concerning element.

Lava typically moves too slowly to be the greatest danger from an eruption, but pyroclastic flows are a different story. These extremely hot, fast-moving surges of gas and tephra were responsible for the deaths of the most famous victims of volcanic eruptions: the inhabitants of Herculaneum and Pompeii. In 79 CE, the pyroclastic flow from Mount Vesuvius that struck Herculaneum reached temperatures of 500°F—hot enough to boil brains and vaporize flesh. Meanwhile, the later, cooler wave that hit Pompeii cooked people's flesh but left their bodies intact, preserving them under the falling volcanic ash.

4. There are multiple ways a volcanic eruption can be fatal.

As Io9 recounts, you could be killed by flying debris, boiling seawater, falling into a lava tube, toxic gases, or volcanic smog (vog).

5. Volcanic eruptions fall into three categories.

Magmatic eruptions occur when gas within magma decompresses, propelling it forward. Phreatic eruptions are caused by the heat from magma transforming water into superheated steam. Phreatomagmatic eruptions happen when water and magma interact.

6. Volcanologists monitor volcanic activity around the globe on a continuous basis.

One key initiative tracking potentially dangerous volcanic activity is the Global Volcanism Program, operated by the Smithsonian National Museum of Natural History. It also releases a weekly report in collaboration with the USGS, which includes a map of recent activity. The International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) specifically watches the Decade Volcanoes—16 volcanoes considered particularly dangerous due to their history of massive eruptions and their location near populated areas. Some of these include Rainier, Sakurajima, Vesuvius, and Santorini.

7. Other planets and moons within our solar system also feature volcanoes.

Jupiter’s moon Io has been known to be volcanically active since 1979, when Voyager 1 imaging scientist Linda Morabito discovered the first signs of active volcanism on a celestial body other than Earth. However, Io is not the only one. For example, while Mars’s volcanoes seem to be dormant or extinct, data from the Venus Express spacecraft indicates that many of Venus’s volcanoes are still active.

8. Sharks are known to frequent a Pacific volcano.

In 2015, scientists captured video of sharks swimming in the acidic, hot, ash- and gas-filled waters surrounding the Kavachi underwater volcano in the Solomon Islands, which lies only 66 feet beneath the surface. This observation suggests that extremophiles could be far more diverse than we had imagined.

9. The most popular map ever sold by the USGS features volcanoes.

"This Dynamic Planet" [PDF] displays over 1500 volcanoes, 44,000 earthquakes, and 170 impact craters, alongside major, minor, and micro tectonic plates responsible for creating these phenomena. Around 60 of Earth’s 550 historically active volcanoes erupt each year.

10. A volcanic eruption in the early 19th century forever changed the world.

In his book Tambora: The Eruption That Changed the World, Gillen D’Arcy Wood argues that the 1815 eruption of Mount Tambora on Indonesia's Sumbawa island created a massive sulfuric dust cloud that drastically altered the planet’s climate for three years. This led to a series of global consequences, including the first worldwide cholera pandemic, the growth of opium markets in China, the U.S.'s first economic depression—and even Mary Shelley’s Frankenstein.

11. A volcano stamp helped persuade Congress to approve the Panama Canal.

Before the Panama Canal was completed in 1915, rival proposals to connect the Atlantic and Pacific included a plan to construct a canal through Nicaragua, which offered more fresh water and fewer malaria risks than Panama. However, it also had significant volcanic activity, and in the early 20th century, one of its stamps depicted an erupting volcano. In 1902, just before a key U.S. congressional vote, a pro-Panama Canal French engineer sent this stamp to all 90 senators to emphasize Nicaragua's volcanic dangers. Panama ultimately won the vote by a narrow margin.

12. Yes, you can surf on a volcano.

Nicaragua’s Cerro Negro, a young and highly active volcano that first erupted in 1850 and has erupted 23 times since, most recently in 1999, features black pebble-covered slopes that you can surf down on a metal-bottomed wooden board—if you're daring enough and maybe have a death wish. Interested? Here’s our seven-point guide to surfing volcanoes.

13. The Earth's most volatile region is a volcanic area known as the "Ring of Fire."

Stretching along the Pacific Rim, the Ring of Fire is a nearly continuous loop of oceanic trenches and hundreds of volcanoes that spans over 25,000 miles. It accounts for 75 percent of the world's volcanic activity, containing 452 volcanoes (both active and dormant), 90 percent of the planet’s earthquakes, and 22 of the 25 largest volcanic eruptions in the past 11,700 years.

14. Volcanic activity has several key warning signs.

According to the USGS’s Volcano Hazards Program, volcanologists monitor for ground shifts caused by magma rising through solid rock, earthquakes triggered by this movement, and changes in temperature and gas emissions. Other signs include cracks in the earth, small steam explosions, melting snow, and the appearance of new hot springs.

15. A volcanic eruption in Iceland in 2010 caused flight disruptions for weeks.

The Eyjafjallajökull volcano erupted on April 14, 2010, and continued for six weeks, releasing magma, ash, and gas. This forced widespread flight cancellations across Europe. Although the eruption itself was relatively small, it had a massive impact due to the way the ash spread unusually far and remained suspended in the atmosphere for an unexpectedly long time, thanks to the irregular shape of the tiny, porous ash particles, as reported by LiveScience reports.

16. NASA is training future Mars settlers on one of Earth’s active volcanoes.

For several years, NASA has been simulating life on Mars on the slopes of Hawaii's Mauna Loa volcano, one of the Decade Volcanoes. Each year, a select group of adventurers who meet the basic criteria for the NASA astronaut program live in a solar-powered geodesic dome. To go outside, they must wear space suits. It’s still a more manageable challenge than escaping poisonous gases and pyroclastic flows.