Nearly three years ago, an island sprung into existence in the South Pacific Kingdom of Tonga, nestling between two older islands in the archipelago.
The new island formed after the eruption of a submarine volcano in the region, which flung ash 30,000 feet into the sky, before it eventually settled in January 2015.
While scientists first estimated that the island with a 400-foot (120-meter) summit would last just a few months, new calculations suggest it could remain in its new place for as much as 30 years.
The island has come to be known as Hunga Tonga-Hunga Ha’apai.
It became visible to satellites in 2015, and is the first of its kind to emerge and survive in the modern satellite era, according to NASA.
A stunning time-lapse released by the space agency this week reveals how its shape has changed since it first emerged, using 33 months of high-resolution satellite data.
Over the last 150 years, there have been three of these ‘surtseyan’ volcanic island formations, with the Tongan being the most recent.
It sits on the north rim of a caldera atop an underwater volcano, which is nearly 4,600 feet (1,400 meters) higher than the surrounding sea floor, the researchers say.
“Volcanic islands are some of the simplest landforms to make“, said Jim Garvin, chief scientist of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
“Our interest is to calculate how much the 3D landscape changes over time, particularly its volume, which has only been measured a few times at other such islands.”
“It’s the first step to understand erosion rates and processes and to decipher why it has persisted longer than most people expected.”
Experts were able to track the formation of the new Tongan island since its beginning, using high-resolution satellite observations.
The scientists first began watching the island after the initial eruption died down, using images from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) instruments to make a 3D map of its topography.
According to the team, there are two potential scenarios that could play out. The island could experience accelerated erosion by wave abrasion, they say.
This would destabilize the tuff cone in roughly six to seven years, leaving behind a land-bridge between the two neighbouring islands.
Or, erosion could occur at a slower rate, which would leave it intact for 25-30 years.
According to the researchers, the new Tongan island may be experiencing similar interactions as seen at Surtsey, where warmed seawater and ash chemically altered the rock to create a tougher material.
And, a similar process could help explain some of the volcanic features on Mars.
“Everything we learn about what we see on Mars is based on the experience of interpreting Earth phenomena,” Garvin said.
“We think there were eruptions on Mars at a time when there were areas of persistent surface water.”
“We may be able to use this new Tongan island and its evolution as a way of testing whether any of those represented an oceanic environment or ephemeral lake environment.”
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