New Delhi: On Saturday, January 15, an explosive eruption of the Hunga Tonga-Hunga Haapai volcano occurred, causing a tsunami in the Pacific Ocean. An underwater volcano, also called a submarine volcano, is located in the South Pacific Kingdom of Tonga, an archipelago of over 170 islands in the South Pacific Ocean 2,000 km northeast of Auckland, New Zealand.
NOAA said on its website that the Geostationary Operational Environmental Satellite (GOES), a joint operation between NASA and the National Oceanic and Atmospheric Administration (NOAA) in the United States, captured the explosive eruption of a submarine volcano located in Tonga.
According to media reports, an underwater volcano erupted after a tsunami hit Tonga and several South Pacific islands. Waves began to crash into coastal homes, and telephone and Internet links were snapped.
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According to NOAA, the blast had a radius of 260 km, or 161.5 miles, and sent ash, steam and gas up to 20 kilometers into the air. It was about seven times more powerful than the previous eruption on December 20, 2021.
In addition, a tidal gauge in Nuku’alofa, the capital of Tonga, measured a tsunami wave of 30 cm, or one foot, as a result of the eruption.
What are the types of submarine volcanoes and what causes them to erupt?
Submarine volcanoes are volcanoes located beneath the surface of the ocean. The eruption throws rock and ash into the water, and the molten lava glows under the water. Submarine volcanoes can occur in three ways.
Underwater volcanoes can be formed due to rift zones found in all of Earth’s major ocean basins. The second type of submarine explosion is caused by the collision of crustal plates. A third type also occurs when a submarine eruption occurs as a result of a magma plume rising through the Earth’s crust over a region of melting in the Earth’s crust.
Rift zones in the major ocean basins of the Earth are where crustal plates are forming. According to NOAA, submarine volcanic eruptions characterize these rift zones. Rift zones, also known as seafloor spreading centers because tectonic plates move away from each other in these areas, are mostly located at depths greater than 2,000 meters, or 1.2 miles.
These are also called divergent plate boundaries.
Therefore, about three-quarters of all volcanic activity on Earth occurs in the form of deep, underwater eruptions. This accounts for more than 70 percent of all volcanic eruptions on Earth. One cannot see the effects of these deep eruptions from the surface of the ocean as they are covered by the view of thousands of feet of water.
Submarine volcanoes play an important role in maintaining the ecosystem of the ocean. When erupting centers or submarine volcanic eruptions occur, they produce a rock called basalt, which is the major rock forming marine trust.
Eruptions that erupt on the ocean floor are mostly local. However, the Earth’s crust may deform as a result of these explosions. According to NOAA, these distortions can be similar to the eruptions of Hawaiian volcanoes.
Submersible basalt flows have a distinctive “pillow shape”, and may also have smooth sheet flows, similar to basalt eruptions on land.
Although submarine eruptions all occur with spreading centers on the ocean floor, they are most common with diffusion centers where plates are separating relatively rapidly. For example, in sea level spreading centers such as the East Pacific Rise, the diffusion rate is 10 to 15 centimeters per year. In areas such as the Mid-Atlantic Ridge, the minimum spread rate may be about one to two centimeters per year.
There are some areas in the ocean known as subduction zones, where crustal plates collide and one plate progressively dives under another and eventually melts again. Submarine eruptions can occur in these subduction zones, or convergent plate boundaries. These underwater eruptions are different from those with outburst centers.
What happens after a volcano erupts under the sea?
Whereas basalt rock is formed as a result of submarine volcanic activity occurring in rift zones, and auricite rock is formed due to subduction zone volcanism. Andesite is a product of the melting of the plate, which is being reduced. Andesitic lavas have high viscosity and high gas content, and therefore, produce violent eruptions.
Scientists have recently discovered and observed active deep andesitic eruptions. Since these occur at critical depths, their explosiveness is reduced.
A different type of submarine eruption occurs when a magma plume rises through the Earth’s crust into a melting zone in the Earth’s mantle. Such eruptions are known as hotspot volcanoes and often form chains of volcanic islands and seamounts. These islands and seamounts are older with increased distance from the surface location on the rising magma plume. Basalt rock is produced as a result of hotspot eruptions.
Submarine volcanoes are hidden an average of 8,500 feet or 2,600 meters below the surface of the water. The global system of mid-ocean ridges is estimated to produce 75 percent of the annual output of magma.
According to an article on the Oregon State University website, submarine volcanoes produce about 0.7 cubic miles, or three cubic kilometers of lava. Magma and lava form the edges of new oceanic plates as a result and supply heat and chemicals to some of Earth’s most unusual and rare ecosystems.
It is estimated that there are more than a million submarine volcanoes, and about 75,000 of these volcanoes are more than half a mile above sea level.
The rate of plate movement plays an important role in determining the type of volcano and the rate of eruption activity.
Submarine volcanoes that occur in the subduction zone are like their subaerial counterparts, with the only difference being that the weight of the water above modifies the eruption style.
Some of Earth’s largest volcanoes are the result of hotspots, leaving linear tracks of seamounts in ocean basins.
Ecosystem Supported by Submarine Volcanoes
Submarine volcanoes create unique habitats, which makes them even more interesting. Seamounts, which are underwater mountains created by volcanic activity, are areas of high biological diversity. Their shape helps deflect food-carrying currents upward and attract a variety of marine organisms, and the crustaceans and fish that feed on them.
Scientists discovered in the late 1970s that some animals can also metabolize inorganic compounds emitted during volcanic activity.
This creates unique communities around hotspots of hydrothermal venting, similar to geyser activity on land.
In 1977, hydrothermal vents and new forms of life were first discovered in mid-ocean ridges, according to an article on the Oregon State University website. Hydrothermal vents, also known as black smoker, are characterized by the presence of water, hydrogen sulfide, and other minerals. The springs have a temperature of about 660 degrees Fahrenheit.
The warm waters host an ecosystem complete with giant clams, mussels, tube worms and other critters that use sulfur, not sunlight, to live.
Vents for hydrothermal fluids produce black “chimney stacks”, and are, therefore, called black smocks. Chimney stacks, made of iron and zinc sulfide minerals and calcium sulfate, can grow to a height of about 40 feet but most are less than 30 feet tall.
Hydrothermal vents were formed recently, following the 1991 submarine explosion in the East Pacific Rise, located in the Pacific Ocean. These areas host tubeworm colonies.
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