Satellite image of Lake Toba
We only have regular volcanoes today, but geologists have found evidence that there have been truly enormous volcanic eruptions in the Earth’s past. Some of these were so large, they would have affected an entire continent, and even the Earth’s climate for years. Geologists call these supervolcanoes; they’ve happened in the past and they’ll happen again.
A supervolcano, or “super eruption” occurs when magma rises from within the Earth’s crust, but it’s unable to break through to release the lava and volcanic gasses. Pressure builds up under the hotspot in calderas until it explodes violently, releasing thousands of cubic kilometers of material in one eruption.
Geologists measure the strength of a volcanic eruption on an index called the Volcanic Explosivity Index. A supervolcano is any eruption that has a magnitude 8 on the VEI, releasing more than 1,000 cubic kilometers in one eruption.
The most recent supervolcanic eruption was thought to be at the Toba Caldera in Sumatra, Indonesia, which exploded about 75,000 years ago. This is the site of a beautiful lake today; the largest volcanic lake in the world. The eruption was so large that it changed the climate of the Earth, plunging the planet into permanent winter for several years.
NASA’s Voyager spacecraft discovered supervolcanoes on Jupiter’s moon Io during its flight past the planet and its moons. Io is in a constant state of volcanic activity, and has several huge calderas on its surface.
Are we going to experience more supervolcano eruptions in the near future? Scientists think they’ve identified all of the large calderas where supervolcanoes might be forming. And the science has gotten to the point that they can predict volcanic eruptions months and even years into the future by measuring mini-quakes and rising ground. They don’t think that any eruptions are likely to happen soon. Sort of like the same chances the Earth has of being struck by a 1 km asteroid.
We have written many articles about volcanoes for Universe Today. Here’s an article about the biggest volcano in the Solar System. And here’s an article about the biggest volcano on Earth.
Want more resources on the Earth? Here’s a link to NASA’s Human Spaceflight page, and here’s NASA’s Visible Earth.
We have also recorded an episode of Astronomy Cast about Earth, as part of our tour through the Solar System – Episode 51: Earth.
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