Supervolcanoes: should we be worried?

Eyjafjallajökull eruption in April 2010. Image credit: Finnur Bjarki Tryggvason via Flickr.

In April 2010 the Icelandic volcano Eyjafjallajökull erupted, causing significant air travel disruptions due to the large volcanic ash cloud that was produced.

The Volcanic Explosivity Index (VEI) is a measure of how explosive a particular volcanic eruption is. The VEI ranges from 0 to 8, and from VEI 2 and up the scale is logarithmic, meaning that an increase in 1 index means that an eruption is 10 times as powerful.

The April 2010 eruption of Eyjafjallajökull was rated as VEI 4. So what effects would a volcanic eruption that rated much higher (say a 7 or 8 on that scale) have?


Supervolcanoes are volcanoes that have had an eruption that is classified as VEI 8. The most recent VEI 8 eruption was the Oruanui eruption of the Taupo Volcano in New Zealand approximately 26,500 years ago. Without any human records for what the effects of this eruption were, it’s difficult to predict exactly what repercussions a VEI 8 eruption would have today.

While they are 10 times less explosive, VEI 7 eruptions have occurred much more recently and can be used by scientists to form predictions for what a possible VEI 8 eruption might look like. The most recent VEI 7 eruption was the eruption of Mount Tambora in Indonesia in 1815. This eruption greatly altered the global climate, resulting in 1816 being known as the ‘Year Without a Summer’. The cooler temperatures resulted in crops failing worldwide and widespread food shortages. European fatality rates were double in that year compared with previous years.

Yellowstone Supervolcano

If you’ve seen the movie ‘2012’ you’d be familiar with another supervolcano, the Yellowstone Supervolcano in the United States.

The Yellowstone Supervolcano has erupted three times throughout history. These three eruptions occurred 2.1 million, 1.3 million, and 640,000 years ago. Based on the frequency of these eruptions, some people have assumed that the supervolcano is overdue for an eruption and could erupt at any moment. If the Yellowstone Supervolcano did erupt, it could blanket the US with volcanic ash, and have an unprecedented effect on the global climate. It could be like 1816, but much, much worse.

So should we be worried?

Luckily for us, supervolcanic eruptions are rare and only occur under very special circumstances. Firstly, there has to be a massive magma chamber (much larger than a normal magma chamber) that is completely full of magma and highly pressurised. This magma chamber then needs a fresh injection of magma from the mantle. The addition of magma into the already highly pressurised magma chamber is enough to cause the massive eruption.

Geologists are also constantly monitoring volcanoes such as the Yellowstone Supervolcano, and they’re getting better at picking up on the signs that an eruption is imminent. Luckily for us, those signs aren’t there, and the odds of Yellowstone erupting in any given year are very small – 0.00014%! It’s also possible that the Yellowstone Supervolcano will never erupt again, so don’t let ‘2012’ stop you from booking that holiday to the US.

2 Responses to “Supervolcanoes: should we be worried?”

  1. Caitlin Jay says:

    Thanks for reading Alice! I guess that that would be the next step, try to remove as many people as possible from the surrounding areas! Depending on how much time they have before the eruption I would say that they might also warn farmers about the possible devastating effects on livestock or crops. Very difficult to actually plan for something like a supervolcanic eruption, especially if the effects are seen for months or years afterwards!

  2. dohertya says:

    Luckily I haven’t seen 2012 so that won’t be stopping me from holidaying in the US (when I get the chance and the money).

    By the way if the geologists ever pick signals what is the next step….run?