Graphic: making an island

A spectacular underwater volcanic eruption spewing smoke and gas thousands of feet into the sky has created a new island in the Pacific Ocean.

The volcano began erupting on Monday and ejected so much lava that by Wednesday it had formed the island about seven miles off the coast of Tongatapu, the main island of Tonga. Satellite pictures revealed the new island still shrouded by smoke, and a huge raft of pumice floating about two miles north of the eruption.

Last night the island was rocked by a 7.9 magnitude earthquake, causing the Pacific Tsunami Warning Centre to issue a warning for neighbouring islands: “This tsunami may have been destructive along coastlines of the region near the earthquake epicentre. Authorities in the region should take appropriate action in response to this possibility.” There were no reports of any damage or casualties on Tonga’s main island and the alert was later cancelled.

Professor Simon Turner, a geochemist at Macquarie University in Sydney, warned that if the volcano continued to erupt it had the potential to be devastating: “Underwater volcanoes can be violent, and have a strong climatic effect. This one isn’t getting into the stratosphere yet but as it continues to grow that is a possibility.”

The island is likely to last several months or even a few years, but will eventually be eroded away by the waves. It is formed of pumice, a type of rock created when lava and gases erupt in comparatively shallow water and are rapidly cooled and fragmented. Being so aerated, the rock is light enough to float.

Ian Wright, of the National Oceanographic Centre in Southampton, said that the eruption was taking place in a volcanic arc in the Western Pacific called the Ring of Fire. Several chambers of magma are thought to be feeding the Tongan volcano.

A team of scientists are on their way to observe the eruption and measure its impacts, including calculating the size of the new island.

A similar eruption two years ago at Home Reef in the Tongan archipelago resulted in a small island being created. Some of the pumice blown out in the eruption floated more than 1,200 miles to reach Australia.

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