Question: Hi James V, I was just wondering if volcanoes on land were to be the only volcanoes that actually erupt, if there is others like underwater ones,(probably the only others) would they erupt two? if yes what would happen?

James Verdon answered on 3 Jul 2012:

Hi ahmedd,
There are LOADS of volcanoes underwater. There’s probably more underwater than there are on land. The mid ocean ridges running through the Atlantic and Pacific Oceans are chains of volcanoes on the ocean floor. The tectonic plates in the middle of these oceans are pulling apart, and molten magma rises up to fill the gaps, creating volcanoes.

When underwater volcanoes erupt, the magma is instantly cooled by the surrounding water, solidifying it mid-eruption. So you tend not to get the huge eruptions that you find on land. Many submarine volcanoes have a lot of hydrothermal activity, spewing super-heated water, laden with chemicals, out onto the sea-bed. There are whole colonies of weird creatures that, rather than relying on sunlight, use the heat and chemicals from the vents to live. Scientists believe that life on earth may have originated in the way, around underwater volcanic vents.

So to sum up, there are loads of underwater volcanoes, and they are really interesting!