Huge volcanic rock raft extending 150 square kilometers (93 square miles) is moving across the Pacific Ocean, scientists say.
The pumice sea – the size of 20,000 football fields ̵
Experts say the mass may have come from an underwater volcano near Tonga that erupted around August 7, according to satellite images.
Sailors are warned to guard against potential danger.
Pumys is a light, balloon-rich rock that can float in water. It is produced when the magma cools rapidly.
Large "rafts" on a volcanic rock are more likely to form when a volcano is in shallower waters, experts say.
- Mass volcanic raft discovered near New Zealand
- Deep sea volcanoes discovered near Sydney
An Australian couple sailing a catamaran to Fiji was the first to report a pumice stone on a raft after carelessness entered the ruins at night.
"The waves were brought down to near calm and the boat was delayed to one knot," Michael Hult and Larissa Brill wrote online on August 16.
"The slippage of the rubble came as far as we could see in the moonlight and with the light of our floodlights."
They were temporarily glued after the rocks clogged their rudder, but were then able to go out of the field.
Since then, they have been sending samples of pumice stone – which ranges from "marble to basketball size" – to researchers at the Queensland Technical University (QUT) in Australia.
"The whole surface has become ground"
Associate Professor Scott Brian, a geologist studying QUT samples, stated that such pumice can be observed about once every five years in the region.
"It's a phenomenon reported over time, usually like islands in the middle of the ocean, that people encounter but then I can't find it again," he told the BBC.
"It may be as if the whole surface [of the ocean] has become Earth. "
Assoc. Brian said satellite images showed the field had split into two main surface masses, with many rear rock bands.
"There are currently more than a trillion pieces of pumice stone floating together, but over time it will disintegrate and scatter throughout the area," he said. By now, the pumice stone is moving west to Fiji and is likely to cross New Caledonia and Vanuatu.
"It may reach Australia in a year, but we do not know if it can continue," says Dr. Martin Jutzeller of the University of Tasmania.
Potential Impact of Reef
Experts say pumice is likely to become a home for marine life as it moves across the Pacific Ocean through ocean currents.
"A lot of life … it can attach itself to pumice stone and be transported thousands of miles away. So it's a way of updating ecosystems somewhere, but it can also introduce invasive species," said Dr. Jutzeller .
If it reaches Australia, it could be a boon for the damaged Great Barrier Reef, some experts say.
- Rock rafts "potential cradles of life"
- Barrier Reef "coral babies" in a mass slump
"This is a potential mechanism for restoring the Great Barrier Reef," says Associate Professor Brian.
"Founded on past seagrass events that we have explored over the past 20 years, it will bring new healthy corals and other reef dwellers."
Coral regeneration has collapsed in the world's largest reef system after unprecedented bleaching events in 2016 and 2017