Pacific island Hunga Tonga-Hunga Ha’apai could survive

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.

 

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

THE NEW ISLAND 

The new island formed after the December 2014 eruption of a submarine volcano in the South Pacific Kingdom of Tonga.

The eruption flung steam, ash, and rock into the air, giving rise to ash plumes that climbed up to 30,000 feet (9 kilometers) into the sky.

It finally settled in January 2015, revealing a newborn island between two older islands in the archipelago, with a 400-foot (120-meter) summit.

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.

The volcanic dome that formed the island stretches roughly .6 miles underwater, from shoreline to the floor of the three-mile-wide caldera.

Initially, experts thought it would only last a matter of months. But now, new calculations suggest it could linger for 6 years or more, with potentially to remain upwards of 25 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.

They also tracked the changes in its coastline and height above sea level.

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.

The researchers say this uncertainty boils down to the lack of information on the initial volume of the island tuff cone immediately after the eruption, before the first images were acquired at the three month mark.

There were dramatic changes that occurred in the first six months, with different rates of erosion taking place to shape the island. While experts suspected this could be the end, they later found a sandbar had formed. By late 2016, it had become more stable

There were dramatic changes that occurred in the first six months, with different rates of erosion taking place to shape the island. While experts suspected this could be the end, they later found a sandbar had formed. By late 2016, it had become more stable

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

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

There were also dramatic changes that occurred in the first six months, with different rates of erosion taking place to shape the island.

At first, it took on an oval shape and was attached to the island that sat to the west.

But, by April, it had changed dramatically.

‘Those cliffs of volcanic ash are pretty unstable,’ said remote sensing specialist and NASA Goddard co-author Dan Slayback of the receding cliffs on the southern side of the island.

At one point, the interior wall was washed over, opening up the crater lake to the ocean, NASA says.

While experts suspected this could be the end, they later found a sandbar had formed. By late 2016, it had become more stable.

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. The image shows the island as it appeared in September 2017, with the yellow area showing how it eroded since January 2015

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. The image shows the island as it appeared in September 2017, with the yellow area showing how it eroded since January 2015

The experts have compared the activity at the new island to that seen off the coast of Iceland, where the Surtsey Island began to form in 1963.

The evidence suggests the site has experienced eruptions in the past as well.

‘There’s a huge amount of material that came out from this eruption, possibly larger than at Surtsey,’ said geologist Vicki Ferrini at the Lamont-Doherty Earth Observatory at Columbia University in Palisades, New York.

‘The other interesting thing is that the two islands that surround this new land mass have some pretty tough substrate, so there’s something happening to help make this solidify and stay in place, chemically.’

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

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

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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