About 50-70 volcanoes erupt every year. Some produce gentle lava flows you can walk alongside. Others generate ash columns that reach the stratosphere and alter global climate. Our database tracks 7,196 recorded eruptions across 956 volcanoes — here's how they work, why they happen, and what makes some so much deadlier than others.
Eruptions Tracked
7,196
Currently Erupting
~40-50
VEI 6+ Events
48
Volcanoes That Erupted
956
What Is a Volcanic Eruption?
A volcanic eruption happens when molten rock (magma), dissolved gases, and solid fragments escape from a volcano's vent onto the Earth's surface. Underground, it's called magma. The moment it reaches the surface, it becomes lava.
The driving force is gas pressure. Magma contains dissolved volatiles — mostly water vapor, carbon dioxide, and sulfur dioxide. As magma rises toward the surface and pressure drops, these gases form bubbles and expand violently, much like opening a shaken bottle of soda. The more viscous the magma, the harder it is for gas to escape, and the more explosive the eruption.
Not all eruptions are explosive. Hawaii's Kilauea produces fluid basaltic lava that flows downhill like a river. Indonesia's stratovolcanoes blast columns of ash 20 km into the atmosphere. The difference comes down to magma chemistry — and it makes the difference between a tourist attraction and a civilization-ending event.
Volcanoes Erupting Now
At any given time, roughly 40-50 volcanoes worldwide are in a state of continuing eruption. "Continuing" doesn't always mean lava is flowing right now — it means the volcano has had eruptive activity without a pause of 3 months or more. About 20 of those are actively producing lava or ash on any given day.
Here are volcanoes in our database with eruptions recorded in 2024-2025 (for real-time eruption tracking, see our active volcanoes page):
Three tectonic settings produce the conditions for eruptions:
Subduction Zones (75% of eruptions)
Where one plate dives beneath another, water from the sinking plate triggers melting in the mantle above. This produces the stratovolcanoes that line the Ring of Fire. Most explosive eruptions happen here.
Hotspots (15% of eruptions)
Plumes of hot mantle material rise from deep within the Earth, independent of plate boundaries. Hawaii and Yellowstone sit over hotspots. These produce mostly effusive eruptions with fluid basaltic lava — less explosive, but the volumes can be enormous.
Rift Zones (10% of eruptions)
Where plates pull apart, magma rises to fill the gap. Iceland straddles the Mid-Atlantic Ridge, producing fissure eruptions and shield volcanoes. The East African Rift is another active example.
Types of Volcanic Eruptions
Volcanologists classify eruptions by their explosivity, from the gentle lava flows of Hawaiian eruptions to the civilization-altering blasts of ultra-Plinian events. Each type is named after a volcano that typifies that eruption style.
The gentlest eruptions. Fluid basaltic lava flows from vents and fissures, sometimes creating spectacular lava fountains. Rarely dangerous to humans unless you're standing right next to a vent.
Named after Stromboli in Italy, which has been doing this for 2,000+ years. Regular, small explosive bursts eject incandescent lava fragments every few minutes. Think fireworks from a volcano.
Short, violent explosions that eject thick clouds of ash and solid lava fragments. The eruptions happen when viscous magma plugs the vent, pressure builds, then blows the plug out. Named after Vulcano in the Aeolian Islands.
Defined by pyroclastic flows — superheated avalanches of gas and rock that race downhill at hundreds of km/h. Named after Mont Pelée's 1902 eruption, which killed 29,000 people in minutes.
The most powerful common eruption type. A sustained column of gas and tephra punches into the stratosphere (20-45 km), blanketing huge areas in ash. Named after Pliny the Younger, who described Vesuvius in 79 AD.
The rarest and most destructive eruptions on Earth. These caldera-forming events eject hundreds to thousands of cubic kilometers of material and can alter global climate for years. The last VEI 7 eruption was Tambora in 1815.
The VEI Scale — Measuring Eruption Size
The Volcanic Explosivity Index (VEI) was created by Chris Newhall and Steve Self in 1982 to compare eruption sizes on a logarithmic scale from 0 to 8. Each step up represents a roughly 10x increase in ejected material. It's similar to the Richter scale for earthquakes — except the gap between levels is even more dramatic.
We've mapped every VEI-rated eruption in our database against the scale. Here's how the numbers break down across 7,196 recorded eruptions:
VEI
Classification
Ejecta Volume
In Our DB
Example
0
Non-explosive
< 10,000 m³
729
Kilauea (ongoing)
1
Gentle
> 10,000 m³
1152
Stromboli (typical)
2
Explosive
> 1 million m³
2304
Galeras 1993
3
Severe
> 10 million m³
765
Nevado del Ruiz 1985
4
Cataclysmic
> 0.1 km³
369
Eyjafjallajökull 2010
5
Paroxysmal
> 1 km³
97
St. Helens 1980
6
Colossal
> 10 km³
42
Pinatubo 1991
7
Super-colossal
> 100 km³
6
Tambora 1815
8
Mega-colossal
> 1,000 km³
0
Toba ~74,000 BCE
The distribution tells a clear story: VEI 2 eruptions (2,304 in our database) are by far the most common. VEI 7 events have only happened 6 times in recorded history. And a VEI 8 supereruption hasn't occurred in roughly 26,500 years (Oruanui eruption in New Zealand).
VEI 6 eruptions happen roughly once per century. VEI 7 events roughly once per millennium. We're statistically overdue for neither — but scientists keep a close eye on known supervolcanic systems like Yellowstone, Toba, and Taupo.
Biggest Volcanic Eruptions in Recorded History
These eruptions reshaped landscapes, altered global climate, and changed the course of human history. We've ranked them by VEI and historical significance:
Most powerful eruption in recorded history. Killed ~71,000 people. Caused the 'Year Without a Summer' in 1816 — crop failures and famine across the Northern Hemisphere.
Explosion heard 4,800 km away. Generated 30m tsunamis that killed 36,000+ people. Lowered global temperatures by 1.2°C. Two-thirds of the island collapsed into the sea.
The 20th century's largest eruption by volume — 13 km³ of magma in 60 hours. Created the Valley of Ten Thousand Smokes in Alaska. Remarkably, no one died because the area was so remote.
Ejected ~10 km³ of material. Cooled global temperatures by 0.5°C for two years. Forced closure of Clark Air Base and destroyed thousands of homes under lahars.
The eruption that buried Pompeii and Herculaneum. Killed an estimated 16,000 people. The preserved ruins became one of archaeology's greatest discoveries.
Killed ~2,000 people and destroyed 9 villages in Chiapas, Mexico. Its sulfur-rich plume caused a measurable global cooling effect.
Volcanic Eruption Hazards
Eruptions kill through multiple mechanisms, not just lava. In fact, lava flows cause relatively few deaths because they usually move slowly enough for people to evacuate. The real killers are:
Pyroclastic flows
Superheated gas-and-rock avalanches at 700+ km/h. Unsurvivable. The #1 volcanic killer in the 20th century.
Lahars (volcanic mudflows)
Mixtures of water and volcanic debris that flow like wet concrete at 60+ km/h. Can travel 100+ km from the volcano. The #2 volcanic killer.
Tephra and ashfall
Volcanic fragments ranging from fine ash to building-sized blocks. Heavy ashfall collapses roofs, contaminates water, and shuts down aviation.
Volcanic gases
SO₂, CO₂, and HF can be lethal in concentrated amounts. In 1986, Lake Nyos in Cameroon released a cloud of CO₂ that killed 1,746 people in nearby villages.
For the volcanoes that pose the greatest risk to human populations, see our most dangerous volcanoes ranking.
Frequently Asked Questions
How many volcanoes erupt each year?
About 50-70 volcanoes erupt each year. At any given time, roughly 40-50 volcanoes are in a state of continuing eruption, though not all are actively producing lava or ash every day. Our database tracks 7,196 recorded eruptions across 956 volcanoes.
What was the biggest volcanic eruption ever?
The biggest eruption in recorded history was Mount Tambora in Indonesia in 1815 (VEI 7), which ejected over 100 km³ of material and caused the 'Year Without a Summer.' The largest eruption in Earth's history was the Toba supereruption ~74,000 years ago (VEI 8), which ejected roughly 2,800 km³ of material.
Can we predict volcanic eruptions?
We can forecast eruptions with increasing accuracy using seismic monitoring, ground deformation (GPS/InSAR), gas emissions, and thermal anomalies. The USGS successfully predicted Pinatubo's 1991 eruption, saving thousands of lives. But exact timing — down to the hour — remains impossible for most volcanoes.
Are volcanic eruptions getting more frequent?
No. Our database shows roughly 50-70 eruptions per year, consistent over the past century. What's increasing is our ability to detect and record eruptions, especially submarine eruptions and small events in remote areas. Better monitoring creates the illusion of more activity.
What happens after a volcanic eruption?
Immediate effects include ashfall, lahars, and pyroclastic flows. Longer-term effects include disrupted air travel, damaged agriculture, climate cooling from sulfur aerosols, and secondary hazards like flooding from blocked rivers. Recovery varies from months (minor eruptions) to decades (major eruptions like Pinatubo).