James Stewart

Super volcanoes don't have the classic cone shape that you might associate with more run of the mill volcanoes. The bodies of magma that feed them are so vast that when the volcano erupts and the magma chamber empties, a huge area of land simply collapses to form a giant crater called a caldera.

Super volcanoes don't have the classic cone shape that you might associate with more run of the mill volcanoes. The bodies of magma that feed them are so vast that when the volcano erupts and the magma chamber empties, a huge area of land simply collapses to form a giant crater called a caldera.

The caldera created by the most recent super eruption in New Zealand is now occupied by Lake Taupo, 186 metres deep and 46 kilometres across at its widest. The next most recent super eruption is probably one of the most famous. About 74,000 years ago, the Toba super volcano on the Indonesian island of Sumatra produced one of the most violent volcanic explosions in Earth's history.

The caldera created by the most recent super eruption in New Zealand is now occupied by Lake Taupo, 186 metres deep and 46 kilometres across at its widest. The next most recent super eruption is probably one of the most famous. About 74,000 years ago, the Toba super volcano on the Indonesian island of Sumatra produced one of the most violent volcanic explosions in Earth's history.

The caldera created by the most recent super eruption in New Zealand is now occupied by Lake Taupo, 186 metres deep and 46 kilometres across at its widest. The next most recent super eruption is probably one of the most famous. About 74,000 years ago, the Toba super volcano on the Indonesian island of Sumatra produced one of the most violent volcanic explosions in Earth's history.

Like Topor, the crater left by the Toba super eruption is now occupied by a large lake. But whereas the New Zealand event 26,000 years ago ejected a little over 1,000 cubic kilometers of material, the Toba super eruption 50,000 years earlier involved at least twice the amounts and perhaps many times more.

Like Topor, the crater left by the Toba super eruption is now occupied by a large lake. But whereas the New Zealand event 26,000 years ago ejected a little over 1,000 cubic kilometers of material, the Toba super eruption 50,000 years earlier involved at least twice the amounts and perhaps many times more.

Like Topor, the crater left by the Toba super eruption is now occupied by a large lake. But whereas the New Zealand event 26,000 years ago ejected a little over 1,000 cubic kilometers of material, the Toba super eruption 50,000 years earlier involved at least twice the amounts and perhaps many times more.

And in case you're having trouble imagining what a thousand cubic kilometers looks like, try to picture a cube of rock and ash as tall as Mount Everest. And you still won't quite be there. Everest is a little under nine kilometers tall, but you're in the ballpark. And it wasn't just rock ash that was ejected from Toba in that gargantuan eruption.

And in case you're having trouble imagining what a thousand cubic kilometers looks like, try to picture a cube of rock and ash as tall as Mount Everest. And you still won't quite be there. Everest is a little under nine kilometers tall, but you're in the ballpark. And it wasn't just rock ash that was ejected from Toba in that gargantuan eruption.

And in case you're having trouble imagining what a thousand cubic kilometers looks like, try to picture a cube of rock and ash as tall as Mount Everest. And you still won't quite be there. Everest is a little under nine kilometers tall, but you're in the ballpark. And it wasn't just rock ash that was ejected from Toba in that gargantuan eruption.

All magma has various gases dissolved in it, such as hydrogen sulphide, sulphur dioxide, carbon dioxide and water vapour. In fact, it's the behaviour of these gases that determines how explosive an eruption is. As the magma moves up through the volcano's plumbing system to be erupted as lava, the pressure decreases and the gases come out of solution.

All magma has various gases dissolved in it, such as hydrogen sulphide, sulphur dioxide, carbon dioxide and water vapour. In fact, it's the behaviour of these gases that determines how explosive an eruption is. As the magma moves up through the volcano's plumbing system to be erupted as lava, the pressure decreases and the gases come out of solution.

All magma has various gases dissolved in it, such as hydrogen sulphide, sulphur dioxide, carbon dioxide and water vapour. In fact, it's the behaviour of these gases that determines how explosive an eruption is. As the magma moves up through the volcano's plumbing system to be erupted as lava, the pressure decreases and the gases come out of solution.

If the magma is runny, like that which feeds the volcanoes on Hawaii, the gases can bubble up and escape. But when the magma is thick and viscous, as is the case at Toba and other super volcanoes, it's much harder for the gases to get out. Now when the pressure drops, the gases explode suddenly, like a shaken bottle of lemonade when the lid is removed.

If the magma is runny, like that which feeds the volcanoes on Hawaii, the gases can bubble up and escape. But when the magma is thick and viscous, as is the case at Toba and other super volcanoes, it's much harder for the gases to get out. Now when the pressure drops, the gases explode suddenly, like a shaken bottle of lemonade when the lid is removed.

If the magma is runny, like that which feeds the volcanoes on Hawaii, the gases can bubble up and escape. But when the magma is thick and viscous, as is the case at Toba and other super volcanoes, it's much harder for the gases to get out. Now when the pressure drops, the gases explode suddenly, like a shaken bottle of lemonade when the lid is removed.

These blast the lava into pieces as fine as ash and as large as boulders. So these gases are responsible for pulverizing some of the erupted material into particles, small enough to linger in the atmosphere for years, shading the planet and lowering temperatures. But sulfur dioxide makes the problem even worse.

These blast the lava into pieces as fine as ash and as large as boulders. So these gases are responsible for pulverizing some of the erupted material into particles, small enough to linger in the atmosphere for years, shading the planet and lowering temperatures. But sulfur dioxide makes the problem even worse.

These blast the lava into pieces as fine as ash and as large as boulders. So these gases are responsible for pulverizing some of the erupted material into particles, small enough to linger in the atmosphere for years, shading the planet and lowering temperatures. But sulfur dioxide makes the problem even worse.