Tonga Underwater Volcano Eruption

An undersea volcano in the Kingdom of Tonga which consists of two small uninhabited islands began erupting on December 19, 2021. Its eruption began innocuously enough, with ashen fumes and little explosions where few people outside the archipelago observed.

However, this volcano, known as Hunga Tonga-Hunga Ha'apai, has forced the entire globe to sit up and be alert on January 15, 2022.

Tonga Region: A Volcanic Powerhouse

With dozens of volcanoes, frequent shallow earthquakes in the oceanic trench, and experiencing two-thirds of all the deep earthquakes in the globe, Tonga is one of the most active locations on the planet. The Tonga subduction zone comprises all of Tonga's volcanic islands and underwater volcanoes. In fact, it was in Tonga where scientists from Columbia University initially proposed the concept of a subduction zone in 1967. This was one of the most important pieces of evidence for the then newly established Theory of Plate Tectonics.

The Hunga-Tonga-Hunga-Ha’apai Volcano

The volcano is commonly identified by Hunga-Ha'apai and Hunga-Tonga, two small uninhabited islands about 100 meters above sea level 65 kilometers north of Tonga's capital Nuku'alofa. However, a massive volcano, roughly 1800 meters high and 20 kilometers broad, lies beneath the sea.

Over the last few decades, the Hunga-Tonga-Hunga-Ha'apai volcano has erupted on a regular basis. Hot lava and steam jets erupted through the waves during incidents in 2009 and 2014/15. But these eruptions were relatively minor compared to the January 2022 eruption.

How does an underwater volcano work? How many of them are in the world?

For the most part, scientists don't know much. More than 70% of all volcanic eruptions take place underwater, and scientists are baffled when it comes to understanding them because the eruptions are hidden beneath thousands of feet of water.

According to Oregon State University, the most productive volcanic systems on Earth are found underwater. They produce magma and lava, which form the edges of new oceanic plates and provides heat and chemicals to some of the world's most peculiar and rare ecosystems.

The majority of submarine explosions take place deep beneath the ocean's surface, resulting in lava flowing down the ocean's bottom. Hundreds of islands have been formed by volcanoes all across the planet, from the Asia-Pacific to Iceland.

According to Oregon State University researchers, if an estimate of 4,000 volcanoes per million square kilometers on the Pacific Ocean's floor is generalized to all oceans, there are more than a million undersea volcanoes. Up to 75,000 of these volcanoes rise more than half a mile (1 kilometer) above the ocean's surface. Many of these volcanoes may be extinct but there are roughly 1,350 potentially active volcanoes.

The Scale of Devastation

Tonga's residents were taken aback by the magnitude of a recent volcanic explosion. Scientists monitoring the Hunga Tonga-Hunga Ha'apai undersea volcano were also taken off guard, failing to detect an eruption that would cause a Pacific-wide tsunami.

The amount of lightning emerging from the volcano's ashy plume began to exceed not only that observed during this eruption, but that seen during any eruption ever recorded as the volcano's explosivity increased.

One expert described the eruption as a "once in a millennium" phenomenon because of its magnitude and scale of its destruction. The volcano spewed gasses and ash over 39 kilometers into the atmosphere, similar to that expelled by Mount Pinatubo in 1991, and caused a shock wave audible in New Zealand and reported as far away as Switzerland.

Scientists believe the explosion was the loudest terrestrial event since Krakatoa's eruption in 1883, and a nuclear-test-monitor global group called the eruption the largest thing they have ever seen, dwarfing the world's greatest nuclear explosions in the past.

Ash has caked on the islands of Tonga, covering houses, sticking to crops, and most likely polluting water systems. The explosion's force also created a rare volcanic tsunami that swept across the ocean, inundating the densely populated island of Tongatapu 65 kilometers away from the epicenter, and forcing inhabitants to evacuate to higher ground. The eruption and tsunami have claimed the lives of at least three persons.

The eruption of the Hunga-Tonga-Hunga-Ha'apai volcano caused Tsunami waves to sweep over the shore of Tonga and rising water levels were observed throughout the Peruvian coast and the Pacific Coast of the United States.

Where Did the Tsunami Hit?

Because of the atmospheric and ocean shock created by volcanic eruptions, tsunami waves can be generated. Underwater landslides and the eruption of the volcano's magma chamber, which causes the sides and top to collapse inward, can also cause them.

Tonga, Fiji, and Samoa were all hit by tsunamis. Shock waves traveled thousands of kilometers, were observed from space, and were recorded 2000 kilometers away in New Zealand. On Tongatapu, the sky was blotted out shortly after the eruption began, and ash began to fall.

Tsunami Risk Zone

People living along the Pacific coasts of the United States and Japan have been urged to stay away from the shore as safety against tsunami waves generated by the Hunga-Tonga-Hunga-Ha'apai volcano

Japan has issued a warning for waves up to three meters high, with 1.2-meter waves hitting the country's south.

Strong currents and waves, as well as coastal flooding, were predicted by the US.

What to Expect Next?

After discharging its wrath, the volcano may now enter a period of dormancy. But it's equally possible that it won't. Researchers who have researched the eruptive history of Hunga-Tonga-Hunga-Ha'apai, which is preserved in layers of hardened ash and bits of volcanic pumice, believe the volcano has a habit of erupting explosively every thousand years — not once but, but in many pulses.

New Zealand scientists Shane Cronin sees two possible outcomes for the volcano. The first is that it has reached its limit for the time being and will be silent for the next 10 to 20 years while magma slowly returns. Another possibility is that new magma rises swiftly to replace the one that exploded, resulting in continual eruptions. However, he believes that the breaches and rifts created by the massive explosion will allow additional gas to escape, and those future eruptions will be smaller, at least for the time being.