The New and the Lost World of Hunga Tonga-Hunga Ha’apai

The newly erupted cone (right), and pre-existing Hunga Tonga (to left), with SSV Robert C. Seamans. Credit: NASA
The newly erupted cone (right), and pre-existing Hunga Tonga (to left), with SSV Robert C. Seamans. Credit: NASA/ Dan Slayback

by Dan Slayback, NASA Research Scientist aboard the SSV Robert C. Seamans / KINGDOM OF TONGA /

What a week! Having just finished an expedition to Earth’s newest landmass, Hunga Tonga-Hunga Ha’apai (HTHH) in the Kingdom of Tonga a few days ago, I thought I’d write a few thoughts on this latest expedition to Earth’s newest landmass.

Shortly after the volcanic eruption that constructed this new island began in December 2014, we were alerted at NASA’s Goddard Space Flight Center, in Greenbelt, Maryland, and initiated collection of relevant satellite imagery. Closely following this over the next several months, we observed rapid erosion of the southern coast due to oceanic wave action, at one point breaching the crater wall and opening the crater lake to the sea. Based on observations to this point, we expected a relatively rapid and possibly complete disappearance of the new island, perhaps within months or at most a few years. But instead, the island has held on!

In mid-2018, with the island just over 3 1/2 years old, I was extremely fortunate to be invited to join a leg of the Sea Educational Association’s SEA Semester/SPICE (Sustainability in Polynesian Island Cultures and Ecosystems) program cruise through the southwest Pacific that passes conveniently close to HTHH. That exploratory visit, one year ago, was extremely valuable to let us get our feet wet (figuratively and literally) in understanding the island system from the ground, instead of solely from a satellite vantage point hundreds of miles in space. We made many useful observations, collected some good data, and gained a more practical human-scale understanding of the topography of the place (such as that the adjacent pre-existing islands, and their rocky shorelines, are almost fortress-like in their inaccessibility). We also saw things not accessible from space, such as the hundreds of nesting sooty terns, and details of the emergent vegetation.

My return this year was to extend and improve the observations we made last year, and to lay the groundwork for continued and new observations into the future. A significant advantage of traveling with SEA is the small army of 26 energetic undergraduates on board the ship, willing and able to help accomplish a wide variety of tasks we set for ourselves; without their help, much of what we accomplished would simply not have been feasible.

Sooty tern soaring in front of Hunga Tonga; Hunga. Credit: NASA
Sooty tern soaring in front of Hunga Tonga; Hunga. Credit: NASA/ Dan Slayback

The core goal of these field expeditions is to improve our understanding of the island’s brief evolutionary history and likely future. The island was formed by a surtseyan eruption, which is a relatively modest explosive eruption (compared to say, Mt St Helens or Mt Pinatubo) occurring in shallow waters. They are relatively common along the active Tonga trench (just over the past few days here, a smoke eruption has been reported further north in Tonga, sending plumes over 15,000 feet into the sky, and a magnitude 5.2 earthquake was reported to the east). But it is less common for such eruptions to construct stable landmasses that survive for more than a few months.

Over the past century, only two other surtseyan events have resulted in lasting edifices: Surtsey island in Iceland (erupted in the late 1960s; the type event), and Capelinhos on Faial in the Azores (mid/late 1950s). In Tonga, there are several examples of such eruptions forming short-lived islands over the past century, with the most recent erupting from the same submarine caldera as HTHH in 2009, only 1-2 km from the current cone; it washed away within half a year or so. The current cone may be persisting perhaps due to a larger volume of material ejected (giving it more time to stabilize before the oceanic wave action and pluvial (rain-caused) erosion erode it away), or perhaps its position between the pre-existing islands has provided a level of protection against oceanic wave erosion.

In any case, the appearance of a new landmass (approximately 190 hectacres or 475 acres in size) has presented the unique and rare opportunity to study a rapidly evolving landscape from space, while observable change is occurring over relatively short periods of time (months to years). One key question to understanding its erosional past and future is to better estimate where erosion is occurring, at what rates, and to isolate pluvial-based gully erosion of the flanks from oceanic wave abrasion of sea-cliffs.

Back home at Goddard Space Flight Center in Maryland, we have been using high resolution stereo satellite imagery to provide one estimate of this, but the extreme relief (gullies and canyons with sheer walls up to 30 meters high) is difficult to accurately resolve with standard space-based stereo pair imagery. Thus, we deployed small commercial drones during our field visit to map the entire island at greater than 10-times the resolution of even the best commercial satellites. With more time and cooperative weather, we could have flown lower and achieved even finer resolution, but we did not want to risk flying the drone to a watery grave in questionable weather. The drone imagery will be processed using structure from motion (SfM) techniques that are better able to resolve the high relief topography than we can achieve with simple stereo pairs.  We collected such imagery last year as well, so when processing and analysis is complete, we will have useful estimates for the quantity of erosion occurring in different regions, and from different processes (rainfall vs oceanic wave abrasion). As we also installed a precipitation gauge on this expedition, in the future we will be able to quantitatively model observed erosion as a function of rainfall amounts and rates.

Hunga Tonga from deep gully on new cone. Credit: NASA
Hunga Tonga from deep gully on new cone. Credit: NASA/ Dan Slayback

The other key question about the island’s future is whether a hydrochemical process termed palagonitization is, in the presence of heat and water, cementing the layers of ash into a much more durable substance, termed palagonite. If the core of the cone is slowly cooking into palagonite, it will be much more likely to resist erosional forces for many decades or longer. If this process is not occurring, then the observed erosional forces may reduce the island to little more than a shoal in a couple of decades.

During our visits, we have collected small fragments of palagonite-looking minerals (lab analysis is needed to confirm), and areas exposed along the southern cliffs (where the rate of oceanic wave erosion is significant) visibly resemble exposed palagonitized zones on Capelinhos and Surtsey. A key finding from this expedition included areas of substantial subsurface heat, detected along the shore of the crater lake at depths from the surface to less than a meter. We had hoped to find cracks venting hot gases in places, and brought along an infrared camera to help detect such, but in the end, a student literally stumbled across this sub-surface heat. While handling a small raft (deployed for sonar analysis of the crater lake bottom), her legs plunged through the soft sediment at the edge of the lake to a depth of a few feet, and found unusually warm pockets. We confirmed temperatures of 100-130F in several zones around the lake, simply by pulling up the sediment by hand.  In any case, this suggests residual heat is circulating near the surface, and therefore may well be doing so within the core of the cone, establishing a critical condition for the formation of palagonite.

Along with helping to answer these key questions, our visit facilitated exploration of other important facets of the island’s evolution, including: bathymetric surveys of the crater lake and coastal shallows; surveys of the flora and fauna; and surveys of and collection of accumulated garbage.

Tern soaring near Hunga Tonga. Credit: NASA
Tern soaring near Hunga Tonga. Credit: NASA/ Dan Slayback

One change that I found particularly striking from one year ago was the development of the vegetation establishing itself on the new land.  In 2018, there were three primary patches of vegetation: two in depositional areas to the northwest and southwest of the cone (near the pre-existing Hunga Ha’apai island), and one on the western flank of the cone itself. Last year, the northwest patch was heavily dominated by near mono-culture of beach morning glory, but this year was host to a much more diverse assemblage of plants (including morning glory, but no longer dominated by it). Conversely, the patch on the western flank of the cone appeared less diverse than last year. However, last year it hosted a boisterous colony of nesting sooty terns, while this year there were no birds present.

Which highlights another major change – the distribution of bird life on the island system. Last year we found nesting sooty terns in two large aggregations numbering likely 1000 birds or more in total in the center and west of the system. This year, however, those areas were entirely unused by the terns, while a smaller nesting colony was found far to the east, abutting the pre-existing Hunga Tonga edifice. We also observed rats and owls, and thus suspect there may be more complex ecological interactions at play here (the terns nest on the ground). However, other bird species were more prevalent, including species not seen last year such as red-footed boobies, tropicbirds, and a good number of petrels and shearwaters. We also saw a much larger number of frigate birds (both ‘lesser’ and ‘greater’ species), than the few observed last year. Although we had a dedicated observer to survey birds (and plants) which helped substantially with bird identification (and relieved the pressure to do this myself, personally imposed as an amateur birder), it was still obvious to me that more species, and more individuals of more species (except the sooty terns), were present this year.

Frigatebird soaring over Hunga Tonga. Credit: NASA
Frigatebird soaring over Hunga Tonga. Credit: NASA/Dan Slayback

The bird life was particularly active around Hunga Tonga, which appears cut from an exotic island adventure film: mostly sheer cliffs rise up to over 400 feet, facing the black volcanic cone (which you could readily imagine emitting a column of smoke), and draped in thick tropical greenery. At Hunga Tonga’s flat top, which appears entirely inaccessible without climbing gear, tropical trees and palms sway in the wind, while scores of brown boobies, noddys, frigatebirds, and tropicbirds soar and call. With the overhead avian cacophony providing the soundtrack, the scene of a lost tropical paradise juxtaposed against the new, somber and foreboding cone of the crater suggests a primeval landscape from a different age.

– Dan Slayback, Research Scientist with Science Systems and Applications, Inc., at NASA’s Goddard Space Flight Center

 

A Sea of Islands

The SEA class of 288, Chief Scientist Kerry Whittaker, Chief Anthropologist Emily Hite, and Tongan observer Pen Vailea attend the Free Wesleyan church in Nuku’alofa, Tonga. Credit: SEA
The SEA class of 288, Chief Scientist Kerry Whittaker, Chief Anthropologist Emily Hite, and Tongan observer Pen Vailea attend the Free Wesleyan church in Nuku’alofa, Tonga. Credit: SEA / Emile Hite

By Emily B. Hite /NUKU’ALOFA, TONGA/

Under the moonlight of Friday, October 11, 2019, I eagerly trekked across Hunga Tonga Hunga Ha’apai (HTHH) with a team from Sea Education Association (SEA) and NASA to complete one final mission: to measure temperatures around the perimeter of the volcano’s crater lake. To our delight, our thermal imaging FLIR readings corroborated the hotspots reported earlier by our human temperature probes (students from the class of 288). Discovering the intermittent pockets of sediment that registered over 120°F was the perfect finale to our five-day research expedition on HTHH.

Lesser frigatebird adult feeds juvenile on Hunga Tonga. Credit: SEA / Emily Hite
Lesser frigatebird adult feeds juvenile on Hunga Tonga. Credit: SEA / Emily Hite

As chief anthropologist for Sea Education Association’s Sustainability in Polynesian Island Cultures and Ecosystems (SPICE) program this fall, I facilitate coursework geared towards understanding the diverse and interlinked human-nature relationships throughout our Pacific sailing track. From American Samoa through Tonga and Fiji to New Zealand, we study the dynamic historical, socio-economic, political, and environmental issues that have shaped, and are shaped by, the unique peoples and cultures of the region. At each port stop, students apply their newly acquired ethnographic skills to interview locals and conduct participant observation to answer their proposed research questions. Their projects focus on a range of topics including architecture, religion, tourism, resistance, and conservation in regards to their impacts on people’s sense of place, or connections to landscapes and seascapes, as well as cultural and ecological sustainability. How does one conduct anthropological research on an uninhabited island?

No one lives on HTHH. This is not particularly unique as there are a multitude of uninhabited islands spread throughout the island nations of Oceania. In the Hunga Ha’apai group alone, where HTHH is located, there are 62 islands, and only 17 are inhabited. As Tongan scholar Epeli Hau’ofa so eloquently argued, Oceania is not a region of tiny, dispersed, islands in a vast sea, it is instead a “sea of islands.” This distinction draws attention to the intimately interconnected island spaces that are made into meaningful places by generations of Polynesian seafarers who sailed through them, explored them, lived and thrived in them, and made them into their homes. While uninhabited, these islands are an integral part of the great networks of islands for Oceania people who identify as being of and from the sea.

Arguably then, we can begin to grasp Hau’ofa’s concept as it pertains to HTHH as we conduct our research. SPICE, by nature, is an interdisciplinary program aimed at integrating anthropology with various ecological, geological, and biological sciences. We have been afforded the opportunity, by the King of Tonga none-the-less, to explore the unique features of HTHH. We are attempting to understand natural phenomena and ecological processes in less than a week here; something Polynesians have been doing throughout Oceania for centuries and building societies upon. Fortunately, we were equipped with 26 passionate students eager to literally jump in and conduct research in an ultimate learning experience.

In addition to my role as an anthropologist, I was able to revitalize my previous life as a wildlife biologist. My inner bird nerd was quickly reignited as I lead teams across desert-like (perhaps Mars-like) rocks, gravel, and sediment in search of new or yet to be “discovered” bird species. We easily identified brown boobies (Sula leucogaster), red-footed boobies (Sula sula), red-tailed tropic birds (Phaethon rubricauda), barn owls (Tyto alba), brown noddies (Anous stolidus), and lesser frigatebirds (Fregata ariel). We smelled the colony of 200+ sooty terns (Onychoprion fuscatus) well before we saw it. We passed frigate bird nests with hungry juveniles, screeching in a manner that I can only describe as that of a screaming child in the most terrifying horror film. I followed the horrific sounds and was able to capture the feeding frenzy on camera.

Two Phoenix petrels (Pterodroma alba) flying low near the north east end of HTHH. Crdit: SEA / Emily Hite
Two Phoenix petrels (Pterodroma alba) flying low near the north east end of HTHH. Crdit: SEA / Emily Hite

It took some time studying the bird book to positively ID a solo pacific golden plover (Pluvialis fulva) and a small group of ruddy turnstones (Arenaria interpres). Three elusive song bird species rapidly fluttered from bush to bush allowing for only blurred photos that will need to be examined further. A pigeon and a marsh bird also evaded my arduous attempts at identification. Based on physical features, specifically the distinct pink legs and black webbed toes, I finally determined that the petrels flying overhead were Phoenix Petrels (Pterodroma alba), an endangered species. Not only have some of these species survived the volcanic eruption in 2015, they are now thriving and colonizing the new landmass through natural processes of ecological succession.

I reflected on our research at HTHH as I listened to the melodic Royal Choir heartily sing hymns at the Free Wesleyan church of Tonga on Sunday, October 13. The King and Queen of Tonga sat in their elegant, plush, noble chairs, separated from us by a guarded section in the front of the church. Does the King know it was us, the 20+ foreign visitors in lava lavas sitting attentively in the back pews, who had just completed the collaborative research project on HTHH? Likely he did not notice us at all. However, through our collaborative research and reciprocal data sharing process, he will receive detailed information about all the accomplishments that SEA, NASA, and the Tongan Ministry of the Environment were able to complete on HTHH with his permission.

In five days, we collected over 100 GB of data from drone flights, photographs, geo-surveys, thermal imaging, and ROV surveys of corals. We collected 600 cubic feet of trash off the beaches and disposed it at Nuku’alofa. By all accounts, our mission was a great success. It has been an absolute honor to be involved in this mission along with SEA, NASA, the students, faculty, crew, our Tongan observer, and all our partners at each port stop. Our experiences on HTHH highlighted the interconnected links between peoples, cultures, and environments throughout the Kingdom of Tonga. As we continue our journey navigating through Oceania on the SSV Robert C. Seamans, our experiences at HTHH have made clear that we truly are in a sea of islands.

Emily B. Hite, PhD Candidate, Department of Anthropology, University of Colorado, Boulder

On this expedition to the Kingdom of Tonga, NASA is partnering with the Tongan Ministry of the Environment and the Sea Education Association, an internationally recognized leader in field-based environmental education at sea. This entry is cross-posted from SEA’s blog with permission.

An Island of Opportunity

Natalie takes off during swim call, with a view of HTHH in the background. Credit: SEA
Natalie takes off during swim call, with a view of HTHH in the background. Credit: SEA

By Natalia Chiapperi & Carlin Schildge /HUNGA TONGA-HUNGA HA’APAI, KINGDOM OF TONGA/

As we begin to wrap up our time here at HTHH, the data collection slowed down and we found some free time to enjoy the beauty and seclusion of the island. The day started late, with an 8:40 wake-up call, the latest we’ve been able to sleep-in in several weeks. After a fun frittata frenzy (don’t you just love alliteration?) we signed up for shifts of anchor watch on the ship and free time on shore. Half of the students ventured to island in the morning, while the other half took to land in the afternoon. Our watch hung around on the ship for the morning. What was shaping up to be a relaxing morning of reading and card games was made much more exciting with a surprise swim call right before lunch. We climbed to the end of the bowsprit for the first time without our harnesses, and suddenly the way down looked like a much further fall than we initially realized. But with the encouragement of our shipmates, we mustered some courage and took the leap!

Cameron, Grace, and Natalie (left to right) at the rim of the Crater Lake. The Crater Lake and the South Shore of HTHH can be seen behind them. Credit: SEA
Cameron, Grace, and Natalie (left to right) at the rim of the Crater Lake. The Crater Lake and the South Shore of HTHH can be seen behind them. Credit: SEA

After lunch wrapped up, we started the daily shuffle of small boat runs to shore, to swap out students and crew who spent the morning on the island. Once on the rocky black shores, the two of us parted ways to chase our separate adventures. Natalie made the long haul across the north shore to the southwest corner with Grace and Cameron to begin a trek up to the crater rim. The path was an easy one to choose – simply go where the crevices are only 10 feet deep instead of 50, and you’re good to go. The mountain was deceptively small; the trek up wasn’t even the hardest part. The 15-minute climb was nothing compared to the 45-march out to the base of the crater. But it was all worth it once we saw the view from the top. We even saw a whale splashing around Mama Seamans! Oh, and we spotted Carlin journeying across the barren island towards the Crater Lake.

A bright patch of juvenile coral perches on a rock in the waters off Hunga Tonga. Credit: SEA
A bright patch of juvenile coral perches on a rock in the waters off Hunga Tonga. Credit: SEA

Carlin broke off with Eliza and Arielle, and we walked over to Crater Lake to investigate the legendary hot spots. Unfortunately, we were unsuccessful in locating them ourselves, but we had a nice time seeing how far we could sink into the sediment (I almost lost my shoe when, after sitting in sediment up to my thigh, my leg found the surface but my shoe did not). After some light whale watching on the south shore, we made our way back for a snorkel around the northern tip of Hunga Tonga. It was absolutely incredible, and I saw some of the healthiest and most diverse corals I will probably ever see. It was amazing to witness the rebirth of the reef and see how resilient an ecosystem can be when undisturbed by human impacts. Colorful reef fish (and the occasional reef shark) darted from rock to rock, where hundreds of precariously perched baby coral polyps grew out of the ashes of the volcanic eruption. We even saw some massive, old heads of coral, covered in ash, with smaller new polyps growing miraculously over them. It was amazingly hopeful to see the coral reef at the beginning of its life, and it left me with hope for the future of the budding diverse ecosystem.

We really appreciated the opportunity to explore HTHH on our own time today, while still carrying the geological and ecological knowledge we’ve come to acquire over the past few days of research. Data collection was still active across the island, as a team continued vegetation and bird surveys and another surveyed the corals using an ROV. And shout-out to our marine debris team as well, who worked tirelessly today to finish removing as much trash from the island as possible. We finished off this perfect day at HTHH with burgers, a beautiful sunset, and a movie night on deck. Once again feeling grateful for every opportunity this island has provided us. Cheers!

– Natalie Chiapperi, Ithaca College & Carlin Schildge, Colby College, proud members of A Watch!

On this expedition to the Kingdom of Tonga, NASA is partnering with the Tongan Ministry of the Environment and the Sea Education Association, an internationally recognized leader in field-based environmental education at sea. This entry is cross-posted from SEA’s blog with permission.

 

Hands-on Research Gets Hot on HTHH, Tonga

Left – Sally and Grace compare surface mud with mud from deeper in the sediment column, while Eva, Katherine, and Olivia look on; Center – Cam holds hot mud up to the camera while Eva looks off camera; Right – Photo of hot mud with stake that is being used to investigate tidal influence within the crater lake. Blue in the thermal camera is not only produced by the cold, but also the underwater areas in the top of the image. Credit: NASA/ Dan Slayback
Thermal images of hot mud. Left – Sally and Grace compare surface mud with mud from deeper in the sediment column, while Eva, Katherine, and Olivia look on; Top right – Cam holds hot mud up to the camera while Eva looks off camera; Bottom right – Photo of hot mud with stake that is being used to investigate tidal influence within the crater lake. Blue in the thermal camera is not only produced by the cold, but also the underwater areas in the top of the image. Credit: NASA/ Dan Slayback

By Cameron Gallant and Katherine H. Webber /HUNGA TONGA-HUNGA HA’APAI, KINGDOM OF TONGA/

KATHERINE: Walking on deck, I welcomed our first sunny day at HTHH; however, upon reaching the island, I was greeted by hot black sand and an all-consuming heat that would last all day. Soon, as a part of the bird/vegetation team, Emily, Arielle, Cam, and I headed towards the southwest corner of the island, which boarders Hunga Ha’apai (which I think looks like a dragon lying down). Its red eye watched over us as we drew near.

CAMERON: The morning was hot, but peaceful. The sound of the waves mixed with the calls of boobies and frigate birds. The vivid green vegetation and reds in the rocks of Hunga Ha’apai set sharply against a bright blue sky and were in crazy contrast to the deep black rocks of HTHH.

KATHERINE: Our team observed a variety of birds, from frigate birds to red tailed tropical birds to a rare red-footed booby! While I was disappointed that we did not see any barn owls, we did discover a mysterious marsh bird, which we will soon identify!

Upon reaching the southwest corner, I was shocked to discover that there was a lot of marine debris scattered along the shore, in the sand and in the grass. Our single large trash bag was not enough to pick up all that we found (shoe soles, plastic bottles, Styrofoam, buoys, long plastic pipes, etc.), so we gathered the trash into piles for a group to collect tomorrow.

Plastic debris collection on HTHH, plastic debris is present on the foreground, with Arielle collecting trash in the background with the cone of HTHH in the distance. Credit: SEA
Plastic debris collection on HTHH. Plastic debris is present on the foreground, with Arielle collecting trash in the background with the cone of HTHH in the distance. Credit: SEA

CAMERON: How can there be shoes in a place where nobody has ever walked? Arielle alone, in about 15 minutes found 14 shoes (all flip flops or sandals), 13 bottles, and two buoys. It’s tough to feel impactful when I know next year more trash will be back. Perhaps HTHH, if it’s picked up each year, can be used as an indicator of the state of ocean bound trash in the area.

KATHERINE: The afternoon was for the crater lake. Watching the still green water emerge from the cover of brown canyons was striking in contrast to the crashing blue and purple surf of HTHH’s southern shore. I had paused between the two bodies of water when I noticed a small wave break not far from shore. I barely had time to alert my companions before a humpback whale breached right before my eyes! You could hear our screams of shock and delight from our ship, the Robert C. Seamans (I’m sure!), and we soon watched her calf breech multiple times, playing in the waves.

CAMERON: Grace thought she felt warm mud yesterday when we did transects to sonar map the bottom of the crater lake. Today, it took us a little while to find the area Grace had stumbled upon and there was some doubt as to if it even existed. Then, there was an excited cry, “I found it! It’s over here!’ Sure enough, as we stood half submerged in the crater lake, our feet sunk through the soft, and uncharacteristically warm mud!

Crater lake group in the water: (left to right) Dan, Adrianna, Eva, Kerry, Jennie, Cameron, Olivia, and Grace standing in the crater lake during hot mud investigation (not pictured: Katherine, Catherine, and Sally). Credit: SEA
Crater lake group in the water: (left to right) Dan, Adrianna, Eva, Kerry, Jennie, Cameron, Olivia, and Grace standing in the crater lake during hot mud investigation (not pictured: Katherine, Catherine, and Sally). Credit: SEA

KATHERINE: I stepped into the cool lake water, surprised as my foot, then ankle, then calf, was submerged until I was knee deep in gravel and mud! Due to a lack of a sediment temperature probe, our chief scientist decided that we would use what we have – our hands, feet, arms, and legs – to conduct our research.

So there we were, wandering knee deep in sediments (waist deep in water), sticking our limbs in and out of the earth, scooping up mud and gravel beneath the sun and clouds. When someone found a hot spot, everyone rushed over (all stumbling with movement hindered) to experience the spa-like sensation. Using a thermal camera, we measured the temperature of the sediment by taking a picture of mud after lifting it out of the water. In
the end, we discovered areas of underwater sediment in our study area (approximately one third of the lake shore) that were hotter than 100°F, with the hottest section at 127°F!

CAMERON:  “I love this mud. It’s not gritty.” I marveled. “Most mud has a certain grit too it.”

“It’s probably ash,” someone replied. Wow. It probably is.

The layering of sediment in the lake was fascinating! There were dark Oreo blacks combined with lighter brown layers to create a roughly inch-and-a-half thick rubbery crust (like firm tofu). This crust sat on top of softer mud mixed with volcanic rocks that provided very little resistance to our feet. Beneath everything was a firm gravely surface that supported our weight. Near one of our hotspots, we found that the sediment was layered in an alternating gravel, mud, gravel, mud fashion.

Throughout the afternoon, we moved along the lake edge and discovered the hot areas were not uniformly around the lake. We hope to feel out the rest of the lake tomorrow. We observed some of the mud has a slight sulfur aroma. The crater lake’s salinity and temperature are also similar to nearby sea water. We set up a temporary stake to monitor the water level to help determine if the lake is tidally influenced. Perhaps there is some
circulation between the lake and the ocean nearby.

KATHERINE: As incredible as the discoveries we are making on this island are, I think it’s important to note that there is nothing like experiencing nature’s wonders firsthand, whether in the splashes of whales or the stateliness of HTHH. So, I encourage all of you to go out and experience your local nature. I hope that you will gain the same appreciation for your natural surroundings as I have for HTHH.

CAMERON: Walking back I just was smiling, trying to wrap my head around the outlandishness of the situation. We spent the afternoon walking around getting muddy in a crater lake and just discovered something nobody in the world knew.

– Katherine H. Webber, B Watch, Best Watch!, The University of Virginia

– Cameron Gallant, A Watch, University of North Carolina at Chapel Hill

On this expedition to the Kingdom of Tonga, NASA is partnering with the Tongan Ministry of the Environment and the Sea Education Association, an internationally recognized leader in field-based environmental education at sea. This entry is cross-posted from SEA’s blog with permission.

“Another Planet:” Exploring Hunga Tonga-Hunga Ha’apai

Collecting a side-scan sonar transect of the crater lake. The Lowrance is in the foreground, with Cam and Grace towing it in another inflatable raft. The crater wall is also in the background. Credit: SEA
Collecting a side-scan sonar transect of the crater lake. The Lowrance is in the foreground, with Cam and Grace towing it in another inflatable raft. The crater wall is also in the background. Credit: SEA

By Grace Callahan /HUNGA TONGA-HUNGA HA’APAI, KINGDOM OF TONGA/

Hello from the newest land mass on earth! I’m Grace, and today was my first day on Hunga Tonga Hunga Ha’apai. (I spent yesterday on the ship, helping to ensure that our anchor wouldn’t slip and allow us to be blown out to sea.) After breakfast and a community meeting on the quarterdeck, I boarded our small rescue boat and was whisked ashore. The sky was blanketed with clouds that occasionally pelted us with rain, a fact which under normal circumstances would have been disappointing, but the weather made the pitch black sand of the beach more intense and the volcano itself, pitted with deep ravines, all the more striking. As I walked across this otherworldly landscape, it was easy to convince myself that I had stumbled onto another planet. That is until a barn owl swooped past me, shattering this illusion. (We believe these owls are eating the rats we have observed on the island, and there is still so much more to discover about the animals here!)

My first task of the day was to hike to the crater lake on the other side of the tuff cone in order to conduct a plankton net tow and to complete the last of the side-scan sonar transects that will allow us to map the contours of the lake basin. We inflated our two rafts, and paddled across the mint green lake, dragging a very fine mesh net behind us. This gave us a concentrated sample of any organisms larger than 60 microns in the lake. Our water samples from yesterday show that the lake is more acidic than the ocean around it, so it will be fascinating to see what organisms have colonized these waters. We have looked at our net tow sample using our ship microscopes, and so far have identified spindly diatoms and barnacle nauplii (larvae)!

Next up, we fixed a sonar device and GPS to one of the inflatable rafts, and towed that across the lake several times. These transects will hopefully allow us to map the bathymetry of the lake itself! In the process of handling and paddling the rafts, I managed to submerge myself up to my chest several times, and eventually gave up on being completely dry ever again. After all this walking, paddling, and hauling of equipment we were all quite ready to head back to the beach and meet the other research teams for lunch.

The cliffs and surf on the south shore of HTHH. Credit: SEA
The cliffs and surf on the south shore of HTHH. Credit: SEA

After lunch, I joined the geosurvey team on a hunt for geothermal hotspots in the ravines that scar the sides of the volcano. Dan Slayback, who has joined us from NASA for this mission, brought along his heat-sensing thermal imaging camera for this purpose. Though we did not succeed today in finding any hotspots, we had fun exploring the ravines and collecting images of interesting rocks for our geologic catalog. On our way back to our home base, we went around the south shore of the island and marveled at the steep, jet black cliffs above us and the raging surf below. We also saw several baby whales happily showing their tails in the waters just off the coast!

As the rescue boat ferried people back to the Seamans in small groups, I decided to go for a swim. Floating in the water with the magnificent volcano looming in front of me, I thought about coming back tomorrow. Hopefully I will hike to the very top of the crater in order to collect samples that will provide vital clues about the soil microbiome of this brand new island. I also want to pick up more of the plastic trash that litters the island, giving back to this place that has already taught us so much. But for now it’s back to the ship, dry clothes, dinner, and another round of planning before bed. Thank you Hunga Tonga-Hunga Ha’apai for your unearthly beauty and for helping us better understand the workings of our Earth and other planets beyond it. I can’t wait to return.

– Grace Callahan, Wellesley College

On this expedition to the Kingdom of Tonga, NASA is partnering with the Tongan Ministry of the Environment and the Sea Education Association, an internationally recognized leader in field-based environmental education at sea. This entry is cross-posted from SEA’s blog with permission.

Early Reports from HTHH, Tonga

Students with the Sea Education Association's SSV Robert C. Seamans after landing on beach of HTHH. Credit: SEA
Students with the Sea Education Association’s SSV Robert C. Seamans after landing on beach of HTHH. Credit: SEA

by Frank Wenninger and Michael Tirone /HUNGA TONGA-HUNGA HA’APAI, KINGDOM OF TONGA/

As we labored down into the zodiac with our gear and rations, the ocean splashed violently around us. Those with hats cowered under the power of the southeasterly winds, and those in the front surrendered to the incessant spraying of the ocean. The 60 HP Yamaha engine roared to life and propelled us to the black sand beachhead on the northeast part of Hunga Tonga-Hunga Ha’apai. On the approach, our coxswain barked disembarking orders and doubled down on the throttle for the landing. The bow of the boat was into the black volcanic sand by the hands of the white foam waves. Following orders, we rolled over our respective sides, plunged into warm Pacific waters, and maintained our hold on the rope that had kept us safe on the journey over. As waves, wind and rain battered us from all sides, we raced to clear the boat of the shoreline. We were eagerly greeted by fellow pioneers who off loaded our gear, and took us to the rendezvous point. Water, sunscreen, and snack; we were here.

As I attempted to free my feet from the soft volcanic sand, my perspective took shape. The black volcanic sand gnawed at my feet as I crawled up the dune where I was met again with the unrelenting southeasterly wind. To my left Hunga Tonga, a 150m high, former island blanketed with vegetation, towered over. On my right, Hunga Ha’apai, also a former island stood in the distance thinly populated with green. Finally, to the center stood the body that bridged the two, a 120m gray volcanic crater. Frigate birds, brown boobies, sooty terns, and thin gray clouds hung over head; tall grasses, trees, coconuts, ferns, hanging vines blow in the wind, and (reported) rats and insects scurry through the brush. Hunga Tonga-Hunga Ha’apai is young, and nature is quickly adapting and exploiting this union.

ank Wenninger paying Respect to Hunga Tonga Hunga Ha'apai, small boats and SSV Robert C. Seamans in the background
Frank Wenninger paying Respect to Hunga Tonga Hunga Ha’apai, small boats and SSV Robert C. Seamans in the background. Credit: SEA

It still is surreal to be on Hunga Tonga-Hunga Ha’apai as the island is only four years old and fewer than 40 people have set their feet on this volcanic island. As some of us have talked to some Tongans while we were in Vava’u, thankfully there weren’t any bad omens or disrespect to their culture for us visiting the island and collecting data unlike other Polynesian islands such as Hawai’i. It is a bad luck to take rocks from the islands of Hawai’i as bad things happen to those that take rocks out of the island. Some people have mailed the rocks back to island in hope to get rid of the bad luck. From where I am from, Guam, it is important to ask for permission from the ancestors to enter certain areas or even to pee in the jungle. Although the people in Vava’u told us there is nothing to worry about, I wanted to pay respect to the island as soon as we got on the shore.

As a Pacific islander, respect is the most important virtue when it comes to every aspect of life. After I did my little prayer on the shore, all the crew got together to pay respect to the island. Soon we were off to complete our mission to help gather data in collaboration with our partners at NASA and with permission granted from the Kingdom of Tonga.

– Frank Wenninger, B Watch, George Washington University

Dan Slayback (right) and Pen Vailea (left) placing down drone/satellite target.
Pen Vailea (left) and Dan Slayback (right) placing down drone/satellite target. Credit: SEA

There is humanity among this beauty. I was fortunate to work with a team that included Dan Slayback, the NASA scientist who expertly orchestrated S-288’s research and Pen Vailea, our Tongan observer who guided and allowed us to do research on the island. Throughout my first day on the island Pen and Dan spearheaded multiple initiatives. First, we deployed a drone to systematically take photographs of the connecting portion of the island, or crater lake part. The drone flew at 300m in high winds and rain. It completed its mission per Dan. We also installed Tonga Geological Service plaques and satellite targets throughout the island to measure erosion. This group, the drone/installation group, summited and circumnavigated the crater lake, and I painfully ran around the rim looking for a different descent route. Other groups collected human debris throughout the island and others mapped the island’s crater lake. It was a productive first day for exploration, education, and stewardship. I hope we continue to have the opportunity to explore and give back to the island. Onto another day at sea, and on Hunga Tonga-Hunga Ha’apai.

– Michael Tirone, C Watch, Bowdoin College

On this expedition to the Kingdom of Tonga, NASA is partnering with the Tongan Ministry of the Environment and the Sea Education Association, an internationally recognized leader in field-based environmental education at sea. This entry is cross-posted from SEA’s blog with permission.

Sailing to Mars via Earth’s Newest Landmass

Intrepid students and SEA assistant scientists deploy the pack rafts and side-scan sonar in the crater lake at HTHH.
Intrepid students and SEA assistant scientists deploy the pack rafts and side-scan sonar in the crater lake at HTHH. Credit: SEA

by Kerry Whittaker, Chief Scientist aboard the SSV Robert C. Seamans / KINGDOM OF TONGA /

On September 27th the SSV Robert C. Seamans departed Pago Pago Harbor, American Samoa, bound for Earth’s newest landmass, located in the Kingdom of Tonga. The ship is a Sea Education Association student sailing and oceanographic vessel with 40 souls on board: student and professional crew, faculty, a visiting scientist from NASA, and an observer from the Tongan Ministry of the Environment. The ship’s destination: a new landmass formed in 2015 in an explosive volcanic eruption. The eruption deposited a pile of ash, pumice, and lava ‘bombs,’ building up a new landmass over the course of a month connecting the two small, uninhabited islands of Hunga Tonga and Hunga Ha’apai.  Perhaps the King of Tonga is scheming up a name for this new landmass, but for now, we’ll refer to it as HTHH.

Sea Education Association has been sailing to remote ocean regions, conducting oceanographic research, and involving students in sail training and scientific exploration for over 40 years.  Our two 134-foot sailing tall-ships are each fully equipped with an oceanographic research laboratory and field sampling technology geared towards studying the chemistry, geology, physics, and biology of the ocean from the surface to deep ocean habitats.  Both ships are designated Sailing School Vessels (SSV), which means that students sail as crew, not as passengers.  The SSV Corwth Cramer operates in the Atlantic Ocean, and the SSV Robert C. Seamans in the Pacific.

Since the formation of HTHH in 2015, NASA has been keenly interested in this landmass as a rare opportunity to examine pathways of land formation and erosion in the time of 21st century remote sensing and scientific technology. HTHH is the first island formed on Earth since the availability of sub-meter resolution satellites including imaging radar and geodetic lidar altimetry. The island has persisted longer than expected, sparking
questions of the erosion dynamics behind its longevity and mechanical stability. NASA’s Mars Exploration Program is most interested in HTHH, as it offers a proxy for understanding important geologic dynamics on the red planet associated with water-based erosion.  One might even consider the island of HTHH “Mars on Earth.”

Map showing the western Pacific with Australia and the Kingdom of Tonga.
Map showing the western Pacific with Australia to the left and the Kingdom of Tonga highlighted in red.

We’ve now arrived here at HTHH, aboard the Robert C. Seamans, which is nimble enough to get close to the island and involve students in this work in collaboration with the Kingdom of Tonga and with our partners at NASA.

As Chief Scientist for the SSV Robert C. Seamans throughout this mission, I have the distinct pleasure of wearing many hats (educator, scientist, shipmate, and my salty blue baseball hat), and facilitating the scientific and educational elements of this work.  As we sailed south from Vava’u, the island emerged from the horizon, otherworldly, wild, and pristine. For months and months, we had planned for this moment. Now, our much-discussed mission fully materialized: a dark grey primordial-looking volcano striped with canyons, dark black saddles leading to green-tufted islands to the East and the West.

We have twenty-six eager college students as integral parts of our scientific mission: to better understand processes of land formation on Earth, so that we might understand it on other planets (e.g. Mars). We’ll conduct our research in partnership with NASA and with the Kingdom of Tonga. As an educator, this experience is a dream.  I’m able to guide students through the process of discovery-to invite them to be scientists, to be stewards of this place, and communicators of our work. To show them the messy, complicated, joyous process of fieldwork. These students are immersed in the pure logistics of it all – of getting people from boat to island (don’t forget the sunblock, the radios, and make sure the datasheets are waterproof!). The need to McGuyver.  The need to open our eyes and question everything we see. I’m not lecturing in front of an undergraduate chemistry bench or over a microscope mimicking the scientific process.  Instead, I’m trudging through tiny volcanic black pebbles through the wind and rain with students trailing behind, wearing bright yellow foulie jackets and rain boots. I can’t help but feel a bit like Miss Frizzle.

We’re headed to the island’s crater lake to map its depth and shape for the first time using pack rafts and a portable sonar device. We’ve wound up and through the canyons lining the volcano’s steep walls, loose volcanic ash towering 30-50 feet above us, documenting and hypothesizing about the rocks and a suspicious white ooze coming from a distinct layer between ash and chunks of basalt.  We’re asking questions, using the human tools of our eyes and senses. We’re collecting data that might help to answer those questions with equipment we’ve personally lugged through force 6 winds in five or so small boat runs back and forth from island to ship throughout the morning. The equipment includes an ROV, two drones, highly sensitive GPS devices, datasheets, trash bags, sonar equipment and pack rafts, all to be deployed by student teams throughout the day, all to be trudged through the tiny black pebbles to the crater lake, the crater rim, the raucous wind-exposed south side beach, and the island’s saddles.  Tomorrow, we’ll test the newest rumor yet (although currently unsubstantiated) – Grace stuck her feet deep in the silt at the crater lake, and it was WARM down there. We’re picking up marine debris (because yes, of course, despite being the newest landmass on Earth, HTHH is covered with plastic trash).

The greatest delight for me, beyond the science and the adventure, is inviting students to engage as integral members in this scientific (and very human) process of discovery.  I am so excited to share this experience on HTHH with this eager group of SEA students.  I’m thrilled to be collaborating with NASA, our visiting scientist Dan Slayback, and our Tongan observer and partners in the Tongan Ministry of the Environment. I’m so fortunate to be working alongside an amazing team of professional crew (assistant scientists, engineers, steward, and mates) sailing aboard the SSV Robert C. Seamans, without whom this work would not be possible.  I’m also endlessly grateful to my co-faculty, Captain and Chief Anthropologist, aboard as masters of our educational and sailing program.  And we’re excited to share our experience with you! Please follow along for the next few days as we accomplish this most exciting mission here at HTHH, Mars on Earth.

On this expedition to the Kingdom of Tonga, NASA is partnering with the Tongan Ministry of the Environment and the Sea Education Association, an internationally recognized leader in field-based environmental education at sea. This entry is cross-posted from SEA’s blog with permission.

Land Ho! Visiting a Young Island

The three year-old volcanic island (black) as seen from the SEA drone. Credit: Woods Hole
The three-year-old volcanic island (center) as seen from the SEA drone. Credit: Sea Education Association / SEA Semester

by Ellen Gray

Excitement was in the air when research scientist Dan Slayback of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, approached a small trio of islands in the South Pacific island nation of Tonga. It was October 8th, and Dan had joined the scientists and students with the Sea Education Association’s SEA Semester South Pacific cruise to visit a three-year-old island he’d only seen from space.

“There’s no map of the new land,” Dan said. It erupted from the rim of an underwater caldera in early 2015, nestled between two older islands. The older islands were on some nautical charts at coarse resolution, and the satellite observations appeared to show shallow beaches on the south side of the new island that would allow them to land. However, while satellites are powerful tools for looking at land on Earth, they are not omniscient about all the details on the ground – these beaches turned out to be too steep and the waves too rough for an easy landing.

The SSV Robert C. Seamans of Woods Hole's SEA Semester program at Hunga Tonga-Hunga Ha'apai. Credit: Dan Slayback
The SSV Robert C. Seamans of SEA Semester program at Hunga Tonga-Hunga Ha’apai in October, 2018. Credit: Dan Slayback

When the volcanic island burst into being in January 2015 it immediately captured the attention of NASA scientists keen to understand how new islands form and evolve on Earth – which may also give them clues about how volcanic landscapes interacted with water on ancient Mars. The new Tongan island is one of only three that has erupted in the last 150 years that have survived the ocean’s eroding waves longer than a few months. Dan and his colleagues Jim Garvin at Goddard and Vicki Ferrini at Columbia University have been watching it from satellites since its birth, trying to make a 3D model of its shape and volume as it changes over time to understand how much material has been eroded and what it is made of that makes it partially resistant to erosion. But while high-resolution satellite observations are revolutionary for studying remote regions – such as tiny islands in the vast Pacific Ocean – they can only tell you so much without actually visiting the place on the ground.

Dan and the SEA scientists and students, as well as a Tongan observer, sailed around to the calmer northern coast of the island, which still has no official name and is referred to by the combined names of its neighbors, Hunga Tonga-Hunga Ha’apai (or HTHH for short). On October 9th, they spent the day taking GPS measurements of the location and elevation of boulders and other erosional features visible in the satellite image.

NASA researcher Dan Slayback standing on the beach of Hunga Tonga-Hunga Ha'apai. Credit: NASA
NASA researcher Dan Slayback standing on the beach of Hunga Tonga-Hunga Ha’apai.

“We were all like giddy school children,” said Dan of their visit. “Most of it is this black gravel, I won’t call it sand – pea sized gravel – and we’re mostly wearing sandals so it’s pretty painful because it gets under your foot. Immediately I kind of noticed it wasn’t quite as flat as it seems from satellite. It’s pretty flat, but there’s still some gradients and the gravels have formed some cool patterns from the wave action. And then there’s clay washing out of the cone. 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 of where it’s coming from. Because it’s not ash.”

Editor’s  Note: Dan later learned that clayey materials washing out from the cone, even a cone from an ash-dominated eruption, is not unexpected. 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 that are deposited in the low, flat areas around the base of the volcano.

Mud was only one of the surprises. Dan and the students were able to get up-close photos of the vegetation beginning to take root on the isthmus connecting the island to its neighbor, and patches likely seeded by bird droppings on the volcanic cone’s flank. A barn owl made a surprise appearance (they occur worldwide; the sighting was not, it turns out, particularly remarkable), likely living on the heavily vegetated older islands, as well as hundreds of nesting sooty terns that had taken shelter in the deep gullies etched into the cliffs surrounding the crater lake.

Vegetation taking root on the flat isthmus of Hunga Tonga-Hunga Ha'apai. The volcanic cone is in the background. Credit: Dan Slayback
Vegetation taking root on the flat isthmus of Hunga Tonga-Hunga Ha’apai. The volcanic cone is in the background. Credit: Dan Slayback
Sooty terns are nesting in the gullies around the crater lake. Can you spot the chicks? Credit: Dan Slayback
Sooty terns are nesting in the gullies around the crater lake. Can you spot the chicks? Credit: Dan Slayback

But Dan was there for the rocks. In addition to collecting small samples (with Tongan permission) for mineral analysis back at Goddard’s Non Destructive Evaluation Lab, the other main goal of his visit was to figure out what the actual elevation was of the island.

“The point is to try to take the satellite imagery and tie it to a known reference point, particularly the vertical elevation. The software that generates Digital Elevation Models (a 3D map) from stereo imagery is using a geoid model, and it’s not great in remote places like this. So if you were standing there with your GPS and you’re looking at the ocean at sea level and it’s telling you you’re at four meters elevation, you’re like, But I’m not! I’m at sea level,” he said. So he wanted to find a reasonable adjustment to the geoid model for local mean sea level.

The cliffs of the crater lake are etched with erosion gullies. Credit: Dan Slayback
The cliffs of the crater lake are etched with erosion gullies. Credit: Dan Slayback

Using a high-precision GPS unit with both a stable and mobile unit, Dan and the students helping him took about 150 measurements that narrow down each point’s location and elevation to better than 10 centimeters. In addition, they used SEA’s drone to do an aerial survey of the island for another layer of observations to use to make a higher-resolution 3D map of the island.

“It really surprised me how valuable it was to be there in person for some of this. It just really makes it obvious to you what is going on with the landscape,” Dan said. One feature that was eye-opening in person was the deep erosional gullies that run down the side of the volcanic cone. “The island is eroding by rainfall much more quickly than I’d imagined. 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. It’s another aspect that’s made very clear when you’re standing in front of these huge erosion gullies. Okay, this wasn’t here three years ago, and now it’s two meters deep.”

A SEA student takes a GPS point in one of the gullies. Credit: Dan Slayback
A SEA student takes a GPS point in one of the gullies. Credit: Dan Slayback

Dan and the SEA Semester group only had one additional morning on the island before bad weather moved in and they had to retreat to the ship. Now back at Goddard, he’s processing the new data and developing a more realistic 3D model of the island, which he and his colleagues will use to figure out its volume and how much ash and volcanic material erupted from the vent on along the rim of the submarine caldera below. Big questions remain, such as what does the shallow sea floor around the island look like and are hydrothermal processes occurring that may solidify the material and allow it to resist erosion for decades to come. Dan hopes to return next year to find more answers.