A submerged volcano on Mount Home Reef in the Tonga archipelago has awakened after 16 years without activity, pointing over the waters and forming a new island with its emissions. Taking place on the 10th of September, the event threw rocks, lava, smoke and ash into the ocean 25 km southwest of Late Island. In a few days, the remains became a new island, measuring 4,000 m² and 10 meters high.
The Geological Survey of Tonga, on 20 September, reported that the island had grown to 6 times its initial size, reaching 24 m². The new territorial extension, however, is temporary: it will likely sink into the sea, just like the last daughter of the Home Reef volcano, in 2006, which took a year to have its crest eroded by the waves. The difference is that the other island was much higher.
Below, satellite capture of the eruption that formed the island:
How are volcanic islands formed?
When too many volcanic gases are expelled during an eruption, a fine powder called pumice, or pumice, is formed, which becomes a type of porous volcanic glass. Not very dense, pumice floats, and even underwater eruptions can create large amounts of the mineral, becoming islands adrift: this is what happened in 2006, when the island formed even threatened navigation in the Pacific.
Since 1852, the Home Reef volcano has raised 5 islands, ranging from 50 m to 70 m in height. In 1984, one of them even boasted a pond. Volcanic activity in the region is driven by the Tonga-Kermadec subduction zone, which has one of the fastest converging tectonic plates in the world.
This means that the Pacific Plate, present at the site, dips down from the Tonga and Kermadec plates at a speed of 24 cm per year, forming the second deepest marine trench in the world and an incredibly active volcanic arc. The area between Tonga and New Zealand has the highest concentration of underwater volcanoes in the world.
The new island, however, is not adrift. Satellite images show ocean discoloration around the Home Reef volcano, likely the result of superheated acidic seawater mixed with chunks of volcanic rock and debris from the eruption, according to NASA experts.
Local volcanic activity poses low threats to aviation and residents near Vava’u and Ha’apai, but sailors should avoid sailing within 4 km of the island, according to a statement from the Tonga Geological Survey. Volcanic ash and steam coming from the island were last seen on Sunday (25), indicating a dormant volcano.