Volcanoes are like vents to the Earth that release lava, small rocks or steam to the surface. In addition to thousands of volcanoes on land, Earth also has underwater volcanoes. The two mountains that will be discussed below are the largest in the world known so far.
What is an Undersea Volcano?
Quoted from Discover Magazine, underwater or underwater volcanoes are fissures mostly buried under Earth's waters where magma can erupt. Basically, the way underwater volcanoes work is almost entirely the same as volcanoes on land.
Usually, underwater volcanoes are found in the depths of the seas and oceans, mostly along the Pacific Ocean. Some of them can also be found in shallow water.
How Are Undersea Volcanoes Formed?
To understand how underwater volcanoes form, it is necessary to understand how land volcanoes generally arise. The mantle, core and outer crust are the three layers that make up the Earth. The main component in the formation of volcanoes is the mantle, which is composed of molten rock and gas known as magma.
Within the Earth's crust, there are areas of weakness, openings, or cracks called fault lines. Volcanic eruptions are especially likely when the mantle is under a lot of stress, especially along fault lines. During the process of this eruption, molten material found in the mantle layer of the Earth's surface eventually finds its way out of these cracks as lava.
Well, so is the case with underwater volcanoes. There is not much difference between the formation of submarine volcanoes and the formation of land volcanoes. The difference is that on land volcanoes, the mantle layer spills magma through cracks in the Earth's surface, whereas on underwater volcanoes, it occurs underwater.
The Largest Undersea Volcano
Underwater volcanoes are less known than terrestrial volcanoes (on land), because underwater volcanoes cannot be observed directly given their location thousands of meters below sea level.
In fact, there are more underwater volcanoes than terrestrial volcanoes, and these seamounts are some of the most active in the world. But the number of underwater volcanoes in the world is still unknown, and experts believe there are several thousand scattered across Earth's oceans. Here are two of the largest underwater volcanoes ever recorded.
1. Massif Guest
Currently, the largest underwater volcano ever recorded is Tamu Massif. This volcano is located in the northwest of the Pacific Ocean about 1,600 km east of Japan.
The Tamu Massif covers an area of 553,000 square kilometers and is about 1,980 m under the sea. This underwater volcano has an impressive height of about 4,460 meters.
Based on research conducted, it is estimated that the Tamu Massif was formed around 145 million years ago, during the Late Jurassic to Early Cretaceous.
The first word of the volcano's name is a combination of the initials of Texas A&M University, where one of the principal scientists studying the volcano, William Sager, is a professor of geology.
Meanwhile, the last word from the name of the volcano is taken from French, namely massif means massive or large, and in geology means most of the Earth's crust.
It is not known when the Tamu Massif last erupted. However, experts believe that the underwater volcano may never erupt again. The Moho Lines (markers of the boundary transition between Earth's crust and mantle), can be found more than 30 kilometers beneath the Tamu Massif.
Part of the top of the Gardner Pinnacles or Pūhāhonu sticks out to the surface of the sea. Photo: NOAA Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve
2. Gardner Pinnacles (Pūhāhonu)
Another of the world's largest underwater volcanoes is Gardner Pinnacles or Pūhāhonu in Hawaiian. Unlike the Tamu Massif, part of this volcano can be seen as it rises above the sea level.
This volcano is located in Hawaii and stands about 52 meters above sea level while its base is believed to be 4,267 meters from the ocean floor. Most of Pūhāhonu, which was first discovered as a volcano in 1820, lies at great depth, and is the same height as the five Eiffel towers.
The crust of this volcano has sunk several hundreds of thousands of kilometers since it first formed millions of years ago because of its magnitude. This volcano is mostly submerged in water and only a small part looks like a turtle. This is why it is called Pūhāhonu in the local language, because it means a turtle rising to breathe.
Like Tamu Massif, Pūhāhonu's last eruption is unknown. But while still active, Pūhāhonu's magma has tested around 1,700 degrees Celsius, making it the hottest magma on record.
Whether these underwater volcanoes will erupt again or not, it should be noted that underwater volcanic eruptions do not have the same effect as volcanic eruptions on land.
Depending on how close to the surface the water is, an underwater volcanic eruption may have different effects. The weight of the water above it functions as a pressure seal if the burst occurs at extreme depths.
However, if the water is shallow, the eruption can heat the water and cause steam, killing marine life in the process. Additionally, their eruptions can also cause ash to rise into the atmosphere, causing further health damage to animals, even humans.
