When the ashes from a December 2014 eruption of a submarine volcano created a 400-foot (120-meter) island in the South Pacific Kingdom of Tonga experts predicted it would last a few months at most. However, over three years later, the land mass, situated between the uninhabited Polynesian islands of Hunga Tonga and Hunga Ha’apai, is showing no signs of dissipating. Now, NASA scientists believe it may be around for as long as 30 years!
The Tongan island, unofficially dubbed Hunga Tonga-Hunga Ha'apai, is only the third “Surtseyan” volcanic island in the last 150 years to emerge and persist for more than a few months. The classification refers to Surtsey Island, which was formed by a similar eruption off the coast of Iceland in 1963 and remains intact to this day.
What’s exciting is that for the first time, the island’s evolution has been recorded in its entirety by NASA’s high-resolution satellites. Jim Garvin, chief scientist of NASA's Goddard Space Flight Center, and his team say the first six months were the most dramatic with the island changing shape almost daily. In May 2015, after the land mass’s interior crater wall collapsed into the Pacific Ocean, the researchers thought the rest of it would meet a similar fate. However, they had underestimated Hunga Tonga-Hunga Ha'apai. By June 2015, a sandbar had formed around the island’s edge, protecting it from further erosion, and things have only improved since.
Team member Vicki Ferrini, a geologist at the Lamont-Doherty Earth Observatory at Columbia University, says, "There’s a huge amount of material that came out from this eruption, possibly larger than at Surtsey. 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." The expert suspects the warm ocean water interacting with the ash may also be helping alter it into a more robust material.
The scientists believe this unprecedented record of the new island’s formation is useful in understanding similar features on other parts of our solar system, especially Mars. They think it may give us insights into if, and how, life came about on the red planet, in its early history. Garvin hypothesizes that two to three billion years ago Mars probably looked similar to Earth, with lakes and small seas filling the planet’s now empty depressions. The expert says, "Volcanic islands are some of the simplest landforms to make. 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 [the island] has persisted longer than most people expected."
The team, which revealed their findings at the American Geophysical Union Fall Meeting in New Orleans on Dec. 11, 2017, say depending on the erosion rate, the island could survive anywhere from six to 30 years. However, before you start making plans to visit Earth’s newest addition, be warned that it is a fraught endeavor. In addition to the unstable cliffs, the picturesque land mass is surrounded by underwater sandbars, making it hazardous for boats. In fact, even the scientists have not dared to make the trip for fear of collision. They instead depended on two world travelers sailing by to capture the close-up images.