NEW ZEALAND: From New Zealand to Tonga, a seafloor ridge in the southwest Pacific Ocean contains the greatest concentration of underwater volcanoes ever recorded. One of these submerged volcanoes erupted on September 10, 2022.
Since then, the Central Tonga Islands’ Home Reef seamount has repeatedly released plumes of steam and ash, oozed lava, and stained the nearby ocean.
A new island rose out of the water eleven hours after the eruption started. On September 14, 2022, as plumes of discoloured water swirled nearby, the Operational Land Imager-2 (OLI-2) on Landsat 9 captured this natural-colour view (see image above) of the nascent island.
Previous studies suggest that volcanic rock fragments, particulate debris, and sulphur are present in these plumes of superheated, acidic seawater.
According to estimates made on September 14 by Tonga Geological Services, the island’s area is 4,000 square metres (43,000 square feet) and its elevation is 10 metres (33 feet) above sea level.
The island had expanded to a size of 24,000 square metres (258,000 square feet / 6 acres) by September 20. The new island is situated northeast of Hunga Tonga-Hunga Ha’apai, northwest of Mo’unga’one, and southwest of Late Island.
Home Reef is situated in the Tonga-Kermadec subduction zone, where three tectonic plates are colliding at the fastest rate in the world of convergence. One of the planet’s deepest holes and most active volcanic arcs are created here as the Pacific Plate collides with two smaller plates and sinks.
Islands formed by submerged volcanoes are frequently transient, however, can last for years. At Home Reef, there have been four documented eruption cycles, including episodes in 1852 and 1857.
Both eruptions resulted in the temporary formation of small islands, and the cliffs on the ephemeral islands that were created in 1984 and
2006 ranged in height from 50 to 70 metres (160 to 230 feet). Although the island created by the same volcano’s 12-day eruption in 1995 endured for 25 years, the island created by the 12-day eruption of the nearby Late’iki Volcano in 2020 washed away after two months.
The Tonga Geological Service stated in an update released on September 20 that “The volcano offers minor dangers to the aviation community and the communities of Vava’u and Ha’apai.”
However, until further notice, “all mariners are urged to travel beyond 4 kilometres away from Home Reef.” The majority of the ash should fall within a few kilometres of the vent, according to the service.
Satellite images of Home Reef’s recent eruption capture the formation of its newest island in stunning detail. The image below was released by NASA using data from the US Geological Survey on September 14.
It shows not only the long trail of smoke but also the intense colouring of the surrounding ocean.
Since 1852, Home Reef has formed islands five times, some reaching 50 to 70 meters in height. In 1984, there was even a small lagoon on the island.
The seamount responsible for these short-lived structures lies in an area of the Pacific Ocean known as the Tonga-Kermadec subduction zone, which contains some of the fastest-converging tectonic plates in the world.
Here, the Pacific Plate is rapidly subducting under two other plates (Kermadec and Tonga) at a rate of about 24 centimeters per year (9 inches), forming the second deepest trench in the world and an extremely active volcanic arc.
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