Undersea volcano erupts, creating a new island

Produced by: Science Popularization China

Author: Blue Ocean Team

Producer: China Science Expo

On November 15, 1963, 32 kilometers south of Iceland in the North Atlantic Ocean, an underwater volcano 130 meters below the sea suddenly erupted, spewing volcanic ash and water vapor columns up to hundreds of meters. At the climax of the eruption, volcanic ash and dust were washed up to thousands of meters in the air. After a day and a night, on November 16, people suddenly found a small island growing out of the sea. People visually estimated the size of the island, which was about 40 meters high and 550 meters long. The waves on the sea surface could not tolerate the newly emerged island, and washed away many volcanic ash and porous foam stones accumulated near the island. People were worried that the young island would be swallowed by the waves. But the volcano kept erupting, and lava poured out like a pouring. Not only did the island not disappear, but it continued to expand and grow. After 1 year, by the end of November 1964, the new volcanic island had grown to an altitude of 170 meters and a length of 1,700 meters. This is Surtsey Island. After being baptized by the waves and nature, the island has withstood severe tests and stood tall on the vast ocean. Some small trees and green grass have actually grown on the island.

(Photo source: veer photo gallery)

Two years later, on August 19, 1966, the volcano erupted again, with columns of steam and lava rushing out of the crater hundreds of meters high. The eruption continued intermittently until May 5, 1967. During this period, the island also took the opportunity to grow, increasing by 0.4 hectares every day and night, and the volcano spewed out about 180,000 tons of lava every hour.

(Photo source: veer photo gallery)

In 2022, an underwater volcano erupted in the waters between New Zealand and Tonga, spewing out a large amount of magma and volcanic ash to form an island with an area of ​​24,000 square meters. The underwater volcano named "Holme Reef" erupted on September 10, and 11 hours later, a small island formed by magma and volcanic ash emerged from the sea.

(Photo source: Xinhua News Agency)

Submarine volcanoes are widely distributed. Many cone-shaped mountains scattered on the ocean floor are their masterpieces. The mountains left behind after volcanic eruptions are all cone-shaped. According to statistics, there are more than 20,000 submarine volcanoes in the world, and more than half of them are in the Pacific Ocean. Some of these volcanoes have aged and died, some are in their young and active periods, and some are dormant, and it is uncertain when they will wake up and "rise again".

Volcanic islands are formed by the accumulation of volcanic eruptions on the seafloor. At the bottom of the world's oceans, there are vast plains, huge mountains, deep trenches, mid-ocean ridges and rift valleys that almost run through the ocean floor of the world, as well as dense volcanic cones and seamounts. The terrain at the bottom of the ocean is much more complicated than that on land. Volcanic islands are divided into two types according to their properties. One is an oceanic volcanic island, which has no connection with the continental geological structure; the other is a volcanic island in the continental shelf or continental slope sea area, which is related to the continental geological structure, but is different from a continental island and is a transitional type between a continental island and an oceanic island.

The existing active volcanoes, except for a few scattered in the ocean basin, are mostly distributed in the fault zones of island arcs and mid-sea ridges in a belt-like manner, collectively known as the submarine volcanic belt. The energy released by earthquake volcanoes around the Pacific Ocean accounts for about 80% of the world's total. Submarine volcanoes, dead or alive, are collectively called seamounts. Seamounts vary in size, with the most common being small seamounts one or two kilometers high, and far fewer seamounts over 5 kilometers high. There are even fewer seamounts (islands) exposed above the sea. The Hawaiian Islands in the United States are the result of submarine volcanoes. There are still five shield volcanoes on the Hawaiian Islands, among which Mauna Loa is 4,170 meters above sea level. Its large crater has a diameter of 5,000 meters and often has red lava flowing out. It erupted on a large scale in 1950 and is a famous active volcano in the world.

From January 14 to 15 this year, an undersea volcano in Tonga erupted violently, followed by a tsunami with a maximum wave height of about 1.2 meters. The volcano, commonly known as Honga Tonga-Hun'aha'apai, is about 1,800 meters high and 20 kilometers wide. It has been erupting regularly over the past few decades. This year's eruption proved that the caldera has fully awakened, and the scale of this eruption was so large that the top of the erupted magma collapsed inward, further deepening the caldera. It has been confirmed to be the "largest explosion" in the Earth's atmosphere recorded by instruments, exceeding any nuclear explosion test and other volcanic eruptions since the 20th century.

Caption: This is a quasi-constant contrast (low-light image enhancement) product image provided by the China Meteorological Administration on January 15 by the Fengyun-3E satellite. The image shows that the texture structure of the volcanic ash mushroom cloud formed during the eruption of the Tonga volcano is clearly visible, forming an umbrella-shaped cloud with a diameter of nearly 500 kilometers. A ring-shaped shock wave appears around the umbrella-shaped cloud and spreads to all sides.

Image source: (Photo provided by Xinhua News Agency and China Meteorological Administration)

From a human perspective, volcanic eruptions are very scary because they will bring huge natural disaster problems to humans. All we can do is to do our best to protect our production environment and try to avoid disasters.