Pin Me

Anatomy of an Underwater Volcano

written by: Darlene Zagata•edited by: Niki Fears•updated: 1/13/2010

Most of us are familiar with a land volcano. We know what it looks like and what type of destruction a volcano can cause. There are volcanoes on the ocean floor as well known as underwater volcanoes or submarine volcanoes. In fact, there are many more beneath the waters than there are on land.

  • slide 1 of 4


    A volcano is a rupture in the planet's crust through which molten rock, ash and gas escape. The opening at the top of the volcano is known as the crater. Although often associated with the ring of fire in the pacific, Volcanoes can form at any location where there is a thinning of the earth's crust. Volcanoes are found on other planets and moons throughout the solar system. Volcanoes derived their name from the Roman god of fire, Vulcan.

  • slide 2 of 4

    Submarine Volcanoes

    Underwater volcanoes, also called submarine volcanoes, are commonly found on the ocean floor. As with those on land, some are active and others are not. In shallow water, the eruption of a submarine volcano may spew steam and debris above the surface of the water. Most underwater volcanoes are at such a depth that they can only be detected with proper equipment and eruptions in deep water may not even disturb the ocean surface.

  • slide 3 of 4

    Underwater volcanoes are often located in areas of tectonic plate movement. Submarine volcanoes behave much the same way as land volcanoes. Some erupt more violently than others. Whereas volcanic eruptions on land create a river of lava flow, water has a rapid cooling effect on lava from a submarine volcano. The lava congeals underwater, forming what is known as pillow lava. Pillow lava forms when eruptions have a low effusion rate. This simply means a slower rate at which the matter and liquid comes forth. Pillow lava may be bulbuous, spherical or tube-like in shape.

  • slide 4 of 4

    Active Underwater Volcanoes

    Scientists have discovered several thousand active underwater volcanoes. It is estimated that there may be more than a million active submarine volcanoes. They are much more numerous than volcanoes on land. Although many of them may be dormant or extinct, meaning they no longer have measurable activity or erupt, there are a multitude of underwater volcanoes that are fully active. The submerged section of the Hawaiian Islands is one of the largest volcanic ridges in the world. Although volcanoes are known for their awesome destructive power it is interesting to note that in some cases, underwater volcanic eruptions and create new islands.