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Volcanic explosivity index facts for kids

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The Volcanic Explosivity Index (VEI) is a way to measure how powerful volcanic eruptions are. It was created by two scientists, Christopher G. Newhall and Stephen Self, in 1982.

To figure out the VEI, scientists look at how much stuff (like ash and rocks) comes out of the volcano, how high the eruption cloud goes, and how strong the eruption seems. The scale goes from 0 to 8. A VEI of 0 means the eruption isn't very explosive, like when less than 10,000 cubic meters of ash and rock (called tephra) comes out. A VEI of 8 means a super-huge eruption that can throw out over 1,000,000,000,000 cubic meters of tephra and send a cloud higher than 20 kilometers (about 12 miles). Each step up on the scale (from VEI-2 onwards) means the eruption is about ten times more powerful.

How Volcanoes Are Classified

The VEI for an eruption depends on how much volcanic material is thrown out, how high it goes, and how long the eruption lasts. From VEI-2 and up, each number means the eruption is 10 times stronger than the one before it. For example, a VEI-3 eruption is about 10 times more powerful than a VEI-2 eruption.

Here's a table showing the different VEI levels:

VEI Material
thrown out
(volume)		 Type of Eruption Description Cloud Height How Often Lower Atmosphere
Impact		 Upper Atmosphere
Impact
Examples
0 Less than 10,000 m3 Hawaiian Gentle Less than 100 m Constant Small None
Kīlauea (current), Mauna Loa (1975, 1984, 2022)
1 More than 10,000 m3 Hawaiian / Strombolian Gentle 100 m – 1 km Daily Minor None
Yakedake (1995), Nyiragongo (1977, 2002, 2021)
2 More than 1,000,000 m3 Strombolian / Vulcanian Explosive 1–5 km Every 2 weeks Moderate None
Stromboli (since 1934), Etna (current), Whakaari / White Island (2019)
3 More than 10,000,000 m3 Strombolian / Vulcanian / Peléan / Sub-Plinian Severe 3–15 km Every 3 months Substantial Possible
Nevado del Ruiz (1985), Ontake (2014), Cumbre Vieja (2021)
4 More than 0.1 km3 Peléan / Plinian / Sub-Plinian Catastrophic More than 10 km Every 18 months Substantial Definite
Laki (1783), Eyjafjallajökull (2010), Taal (2020)
5 More than 1 km3 Peléan / Plinian Cataclysmic More than 10 km Every 12 years Substantial Significant
Vesuvius (79 AD), Mount St. Helens (1980), Hunga Tonga–Hunga Haʻapai (2022)
6 More than 10 km3 Plinian / Ultra-Plinian Colossal More than 20 km Every 50–100 years Substantial Substantial
Krakatoa (1883), Novarupta (1912), Mount Pinatubo (1991)
7 More than 100 km3 Ultra-Plinian Super-colossal More than 20 km Every 500–1,000 years Substantial Substantial
Santorini (1620 BC), Tambora (1815)
8 More than 1,000 km3 Ultra-Plinian Mega-colossal More than 20 km More than 50,000 years Vast Vast
Yellowstone (2.1 million years ago, 640,000 years ago), Toba (74,000 years ago)

Scientists have found about 40 eruptions with a VEI of 8 over the last 132 million years. The most recent VEI-8 eruption was the Oruanui eruption from Lake Taupō in New Zealand, which happened over 27,000 years ago. This means there haven't been any VEI-8 eruptions in the last 11,700 years.

There have been at least 10 eruptions with a VEI of 7 in the last 11,700 years. By 2010, the Global Volcanism Program had recorded the VEI for 7,742 volcanic eruptions that happened in the last 11,700 years. About half of these eruptions had a VEI of 2 or lower, and 90% had a VEI of 3 or lower.

Things the VEI Doesn't Measure

The VEI is a great tool, but it has some limits. It treats all volcanic materials like ash, lava, and lava bombs the same. It doesn't consider how heavy or bubbly these materials are. Also, the VEI doesn't measure the total power or energy released by an eruption. This makes it hard to use for very old eruptions that weren't observed.

While the VEI is good for classifying how explosive an eruption is, it doesn't tell us much about how the eruption affects the atmosphere or the climate. For that, scientists often look at how much sulfur dioxide gas is released.

Lists of Notable Eruptions

If you want to learn more about specific eruptions, check out these lists:

  • Timeline of volcanism on Earth
  • List of volcanic eruptions 1500–1999
  • List of volcanic eruptions in the 21st century
  • List of volcanic eruptions by death toll
  • List of large Holocene volcanic eruptions (VEI-5 to VEI-7)
  • List of large volcanic eruptions (VEI-5 to VEI-8)
  • List of largest volcanic eruptions (VEI-7 to VEI-8)

See also

Kids robot.svg In Spanish: Índice de explosividad volcánica para niños

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