In December 2014 a new island appeared in the South Pacific, just off the coast of Tonga. Then, almost four years later, scientists visited the landmass and – according to a January 2019 NASA blog post – giddily discovered signs of life there. The excitement was to soon wear off, though – because there was a major catch about the island.
When it comes to the Earth’s geography, the last thing we can expect is stasis. After all, since the beginning of our planet’s history, changes as gradual as erosion and as sudden as earthquakes have shaped the layout of its landmasses. Tectonic plates constantly move around, too, rearranging continents – and even oceans.
Another cause for shifts in our planet’s geography is climate change. Take, for example, the island of Tangier, which sits in Chesapeake Bay, Virginia. Tangier’s 500 inhabitants speak in an English dialect that’s unique to their hometown, and they have a rich history of crabbing in the bay waters. However, their island may not be around for much longer.
You see, since the mid-19th century, Tangier has seen more than half of its square footage vanish into the surrounding seas. Nowadays, in fact, the island covers a little over 1 square mile, and annually a further 15 feet of its coastline is disappearing beneath the ocean. So, without a reversal in climate change, scientists say that Tangier may be entirely underwater in a quarter-century – which will leave residents needing to create new lives on the mainland. Other islands in danger of suffering the same sad fate include the Seychelles and the Maldives.
Yet while many islands face the threat of encroaching waters, geographers have noticed new potential perils popping up, too. The Pakistani city of Gwadar, for instance, experienced a 7.7-magnitude earthquake in September of 2013. And in the aftermath of the shock, the island of Zalzala Koh rose from the waters just off the coast.
Zalzala Koh didn’t last long, however. Just three years after the isle had emerged, it sank back into the waters. And it’s not alone. Elsewhere, Shelly Island, off the coast of North Carolina’s Outer Banks region, also appeared and disappeared quickly. In April of 2017 the extra-large sandbank started to form thanks to strong winds and a relatively mild storm season. But by February of the following year, the island had vanished from view.
New islands can also come to be as a result of volcanic activity. In Hawaii, for example, the Kilauea volcano has emitted enough lava to create almost a mile of fresh land off Hawai’i – otherwise known as the Big Island. And a two-year-long eruption on the island of Nishinoshima, Japan, likewise created an entire new landmass – which was christened Niijimi.
Now, among the Pacific’s more active underwater volcanoes is Kavachi – also referred to as Rejo te Kavachi, which translates as “Kavachi’s Oven.” It’s an apt title, too, given that the volcano has had more than ten eruptions of note since the latter part of the 1970s. However, these fiery events have yet to produce a landmass that’s sufficiently big to withstand erosion – and so none of the islands have lasted.
Another interesting case is that of the Jadid and Sholan Islands, which form part of Yemen’s Zubair archipelago. These islands appeared in 2011 and 2013, respectively, as the result of volcanic emissions in the Red Sea. And while the region may not be one that you’d readily associate with such events, the island group actually sits in the African rift system – which scientists predict will see more land-forming activity in the near future.
Then there’s Tonga – a Polynesian country that’s made up of a whopping 169 different islands that together constitute around 290 square miles of territory. Tonga’s population of just over 100,000 people is spread out over 36 of these isles, although the majority of those people live on the nation’s principal island, Tongatapu.
Tonga’s many islands also lie along part of the Tonga-Kermadec volcanic arc – a massive entity that stretches from Fiji to New Zealand. Magma forms there when tectonic plates meet and push under the Earth’s surface. And owing to the resulting pressure and heat, the fiery fluid erupts.
Now, one of the underwater volcanoes within this active chain is Hunga Tonga-Hunga Ha’apai. The submarine peak sits along an active seismic area that cracks through a couple of islands – named Hunga Tonga and Hunga Ha’apai, respectively. Only a mile-long stretch of water actually separates the two, and each island is a little over a mile in length.
What’s more, although neither of its neighboring islands has human inhabitants, Hunga Tonga-Hunga Ha’apai has nonetheless caused a stir in the past with its eruptions. It lies less than seven miles from Tongatapu, the capital city of Tonga, after all. And in 2009 the volcano exploded, shooting steam, ash, smoke and pumice high into the air.
Kelepi Mafi, Tonga’s head geologist, found that the eruption had originated from a couple of different places on the volcano. One source had opened up a few hundred feet from the shoreline, while the other had appeared on the island of Hunga Ha’apai itself. Both spewed enough ash over the island to destroy its plant and animal life. And incredibly, the emerging lava subsequently cooled to create hundreds of square feet of new land.
However, as it turned out, the 2009 episode was just a warmup for another eruption of Hunga Tonga-Hunga Ha’apai. Towards the end of 2014, you see, multiple earthquakes shook the area, foreshadowing potential volcanic emissions. The eruption itself then started in mid-December of that year, when fisherman observed steam rising from the volcano.
Ten days later, the eruption was still going, with ash and smoke now filling the air. And at the start of 2015 that ash cloud had reached a height of nearly 10,000 feet into the sky. Then, on January 15, it was observed that the plume had tripled in size. It was so big, in fact, that airlines had to redirect or cancel flights through the area.
Once again, Tongan officials pinpointed a pair of vents – one 300 feet from the coast and another on the island of Hunga Ha’apai. And together, these openings violently erupted with both thick ash and large rocks, some of which shot up more than 1,000 feet into the sky. So much material was emitted from each of the vents, in fact, that on January 16 a brand-new island had become visible in the South Pacific.
However, scientists assumed that the volcanic island wouldn’t be around for long; the sea would likely break down the new landmass before long, they said. In the meantime, though, it measured about 0.6 miles in width and 1.2 miles in length while reaching a height of over 300 feet. And just a few days after the island had formed, it housed the sole source of the ongoing eruption, as volcanic activity had begun to subside.
January 26, 2015, ultimately marked the end of the eruption. And by then, the island had grown further; it was now almost 400 feet high. What’s more, the landmass stretched far enough to reach Hunga Ha’apai – and was only some 700 feet shy of meeting Hunga Tonga.
When the volcanic activity in the area had settled, volcanologists then got a chance to examine the exciting new landmass. And, rather than the months that had first been predicted, the scientists concluded that the formation would in fact endure for several decades. How so? Well, it’s all thanks to its unique composition. You see, a reaction had apparently occurred when the volcanic ash had met the ocean waters, which had fortified the former into a stronger configuration of rock.
But volcanologists weren’t the only people interested in investigating the mechanics of the new island – which shares a name with the volcano from which it was formed. NASA’s Goddard Space Flight Center had their eyes on Hunga Tonga-Hunga Ha’apai, too, as the scientists there noticed that the way in which it had eroded seemingly mirrored the gradual movements of land formations on Mars.
The head scientist at the NASA Goddard Space Flight Center, Jim Garvin, said via the NASA website, “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[ing] erosion rates and processes and to decipher why [Hunga Tonga-Hunga Ha’apai] has persisted longer than most people expected.”
Garvin went on to say, “Everything we learn about what we see on Mars is based on the experience of interpreting Earth phenomena. 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.”
Initially, the NASA team conducted all their research from a distance. They relied on high-tech satellite imagery, in fact, which used radar and optical sensors to capture the scene – even if cloud cover was present. Then, the scientists utilized the resulting pictures to map out Hunga Tonga-Hunga Ha’apai – as well as the way in which it had developed.
In October of 2018, though, researchers took their work a step further. The Goddard Space Flight Center’s Dan Slayback, other experts and a selection of students all went aboard a Sea Education Association cruise to travel to Hunga Tonga-Hunga Ha’apai in person. After all, “high-resolution satellite observations… can only tell you so much,” as the January 2019 blog post on the NASA website pointed out.
Seeing the island close up didn’t go without a hitch, however. “There’s no map of the new land,” Slayback explained. And this meant that all the crew had to go on were the images that they’d collected previously. The researchers thought they saw shallow waters on the island’s south side, for instance. But upon arrival, they realized that the surf there was harsh and that the shoreline was sharply inclined – which made landing, in reality, extremely tricky.
Fortunately, though, the experts had a plan B, and the team instead sailed from the island’s south end to its north side, where gentler waters allowed them to dock. So it was that on October 9, 2018 – their first day on land at Hunga Tonga-Hunga Ha’apai – the researchers made their own GPS readings and examined various features that they’d observed using the radar and optical-sensor visuals.
Slayback’s initial steps onto the island also presented him with his first surprise. “In the satellite images, you see this light-colored material. It’s mud – this light-colored clay mud. It’s very sticky. So even though we’d seen it, we didn’t really know what it was, and I’m still a little baffled [about] where it’s coming from because it’s not ash,” he reported.
Later, however, Slayback learned that the appearance of mud on a volcanic island was nothing uncommon. “Similar mud deposits have been observed on other small oceanic island volcanoes as a weathering product from tropical rains that wash fine particles down from the higher elevations and turn them into small mud-flows,” the NASA blog post explained.
But mud was only the first of many unexpected finds on Hunga Tonga-Hunga Ha’apai. For instance, Slayback and the rest of the team additionally discovered that vegetation had begun to take root on the stretch of land connecting the new island to Hunga Ha’apai. They also theorized that bird droppings had actually been the catalyst for said growth.
With the vegetation came some wildlife, too. For example, the researchers happened to see a barn owl – which may seem like a strange creature to be flying through the South Pacific. However, according to the NASA blog, “[Barn owls] occur worldwide. The sighting was not, it turns out, particularly remarkable.”
More interestingly, though, the team suspected that the owl had flown over from one of the larger, older nearby islands where plant life is more plentiful. The researchers also discovered that hundreds of seabirds called nesting sooty terns had made their way to the new island. And these terns had furthermore begun hiding out “in the deep gullies etched into the cliffs,” the blog revealed.
However, for Slayback, the biggest draw to Hunga Tonga-Hunga Ha’apai was its rocks. And as a result, the scientist gathered pieces that he was to fully examine back at his laboratory. Slayback also aimed to measure the territory’s elevation so that he could “take the satellite imagery and tie it to a known reference point,” he said.
In fact, with help from the students, the NASA scientist managed to gather numerous pieces of data from around the Tongan island. And the team’s work helped to hone the recorded elevations of the island to “better than 10 centimeters,” the blog post proclaimed. Then, the researchers launched a drone to capture more images, which would improve the resolution of future 3D maps of the landmass.
For Slayback, then, the trip provided far more insight than he’d initially expected to gain. “It really surprised me how valuable it was to be there in person for some of this,” he said. “It just really makes it obvious to you what is going on with the landscape.” However, a closer look at the area revealed something troubling: estimates about the island’s lifespan may have been generous.
“The island is eroding by rainfall much more quickly than I’d imagined,” Slayback revealed. “We were focused on the erosion on the south coast where the waves are crashing down, which is going on. It’s just that the whole island is going down, too.” Plus, there were big topographical changes that had appeared in the course of only a few years since the island’s formation – and they, too, pointed to the likelihood of a quicker demise.
“It’s another aspect that’s made very clear when you’re standing in front of these huge erosion gullies,” Slayback added. “Okay, this wasn’t here three years ago, and now it’s two meters [6.5 feet] deep.” Nonetheless, he and the rest of the Goddard team would continue to gather as much valuable information from the island as they could.
After his expedition to Hunga Tonga-Hunga Ha’apai, Slayback returned to Goddard, where he pressed on with data processing. He also used the new images of the island to improve the 3D model that NASA has created. And he and his associates will use all of this together to calculate the landform’s volume.
Interestingly, the NASA team can, in addition, use their upgraded data to work out the amount of volcanic matter that was emitted back in 2014 and 2015. And they hope to see what the bottom of the ocean around Hunga Tonga-Hunga Ha’apai looks like, too. The scientists also wonder if the island may even become more solid – and thus stay around for longer than predicted.
For now, though, Slayback continues his work at NASA’s Goddard Space Flight Center, hopefully clarifying many of the questions that still linger about Hunga Tonga-Hunga Ha’apai. And he has stated in the NASA blog post that he wants to travel back to the South Pacific in 2020 to help him in that quest.