Eruption simulator
Dial the Volcanic Explosivity Index from a quiet lava flow to a super-eruption and watch the ash column grow in real-time 3D.
Cataclysmic — Large eruption; widespread ashfall capable of grounding aircraft.
Plume height
10–25 km
ash column
Ejecta volume
> 0.1 km³
tephra
Eruption style
Peléan / Plinian
How often
~ Yearly (somewhere)
globally
Real example
Eyjafjallajökull (2010)
Reading the eruption
The VEI is logarithmic
Each step up the Volcanic Explosivity Index is roughly ten times more erupted material. That's why the jump from VEI 5 to VEI 6 — Mount St. Helens to Pinatubo — looks so dramatic in the plume.
Plume height matters
Big eruptions punch ash into the stratosphere (20–40+ km). That's the ash that grounds aircraft and, for the largest eruptions, reflects sunlight and cools the climate. The side ticks mark 10 km of altitude.
From play to forecast
This simulator shows what an eruption of a given size looks like. Forecasting whether one is coming is a separate, probabilistic problem — see our eruption forecast model.
See how real eruptions are forecast in the eruption forecast model, browse active volcanoes, or learn what drives volcanoes.
FAQ
Volcanic eruptions: frequently asked questions
What is the Volcanic Explosivity Index (VEI)?+
The VEI is a 0–8 scale that rates the size of an explosive eruption from the volume of material erupted and the height of the ash plume. It is logarithmic: each step up represents roughly ten times more erupted material, so a VEI 6 is enormously larger than a VEI 3.
How high can a volcanic ash plume reach?+
Small eruptions barely clear the crater, but powerful Plinian eruptions punch 20–35 km into the stratosphere, and the very largest (VEI 7–8) can exceed 40 km. Stratospheric ash is what disrupts aircraft and affects the climate.
What was the biggest volcanic eruption in history?+
In recorded history, Tambora in 1815 (VEI 7) caused the 'Year Without a Summer.' Pinatubo in 1991 (VEI 6) cooled global temperatures by about 0.5 °C for a year. In the geologic record, supervolcanoes such as Toba (~74,000 years ago) reached VEI 8.
Why do large eruptions cool the climate?+
Big eruptions inject sulfur dioxide into the stratosphere, where it forms tiny sulfate aerosols that reflect sunlight back to space. This can lower global temperatures for months to a few years after the eruption.
Can volcanic eruptions be forecast?+
Eruptions can be forecast probabilistically — not predicted to the day. Rising unrest signals (earthquake swarms, ground deformation, gas emissions and the official alert level) raise the estimated probability. QuakeGlobe's forecast model combines these with each volcano's long-term eruption rate.