Volcanoes located under water are also known as submarine volcanoes. There are at least 1,500 active volcanoes on the surface of the earth, but it is estimated that there may be more than 10,000 volcanoes in the Pacific Ocean alone.
Underwater volcano facts inform us that almost all submarine volcanoes are located near the boundaries of two adjacent tectonic plates. As the tectonic plates move away or towards each other, lava that is present below the surface of the earth, is thrown out with pressure through a fissure on the earth’s surface. This is known as volcanic eruption.
Volcanic eruptions in shallow water can throw underwater material into the air. The Hawaiian islands were formed due to such volcanic eruptions.
One of the latest examples of underwater volcanic eruptions is Surtsey island, south Iceland. The earth surface under the sea was literally lifted up during the eruption, and this resulted in the formation of the Surtsey Island!
Tremendous heat of magma, the liquid or molten rock, often creates a crack in the surface of the earth, and leads to volcanic eruption.
Water exerts higher (about 250 times more pressure) pressure on the surface of the earth than air. This higher pressure can lead to an underwater explosion.
Magma is present in the mantle, the layer below the earth’s crust. When a crack relieves the pressure, the magma rises upward along with gases. This is known as the eruption of an underwater volcano.
Underwater magma cools and solidifies much more quickly due to presence of water. It often gets converted into volcanic glass.
When the magma reaches the surface of the earth, it is known as lava. It cools and settles down in a pile-like structure or tall structures of various shapes. This is how underwater ridges are formed.
Submarine volcanoes which are very close to one another, and which are found in the form of a chain or circle, are referred to as the ‘ring of fire’.
More research is required to understand the role of these volcanic eruptions in global warming. It has been noticed that these eruptions lead to warmer water and higher CO2 levels.
Since most underwater volcanoes erupt at a depth of about 2200 meters below the sea level, where the pressure is more than 218 atmospheres, water cannot boil. Absence of boiling sound makes it difficult to detect an underwater eruption, even with the help of hydrophones.
These days, remote operated vehicles are used to study the effects and patterns of underwater volcanic eruptions. Scientists are studying marine life adaptations in the deep and hot environment surrounding the volcanoes.
Seamounts are nothing but the structures formed by extinct volcanoes under the sea. They rise from the sea floor but remain way below (hundreds to thousands of meters below) the surface of the sea. So they are not described as ‘islands’. Such seamounts can spring up abruptly during underwater eruptions to at least 1,000 meters above the seafloor.
https://sciencestruck.com/underwater-volcano-facts
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