How Do Underwater Volcanoes Erupt?

Video Transcript

"Very commonly what you're going to get with oceanic eruptions are what are known as pillow basalts. You're going to get rocks, the lava pouring out and because it hits the water, it cools much, much faster than it will in air and what you get are just blebs or blobs of this stuff coming out and cooling very, very rapidly. So they look literally like pillows, that's why they're called pillow basalts and basalt is the type of rock that you find typically in the ocean bases. So it's a very dark, heavy, dense rock and it's iron and magnesium rich. So you get that and that type of lava tends to be thinner and soupier than what you find on land so it tends to flow and that's another reason it gives you those pillows. You also get those gas eruptions occurring, they occur underwater also but a lot of times again, there you have the cooling effect so you get what we found in the last 20 years, the black smokers and hydrothermal vents and these really weird communities or organisms that live around these things and that's again, from this hot water and from these gases erupting out of these volcanic eruptions. It's the same thing that happens on land, there it just dissipates into the air instead of being pumped into the water."