Over four days, Brennan Phillips’ expedition team boated closer and closer to Kavachi, an underwater volcano off the Solomon Islands.
“Absolutely, we were scared,” says Phillips, a National Geographic Society/Waitt Grants Program grantee. “But one of the ways you can tell that Kavachi is erupting is that you can actually hear it—both on the surface and underwater. Anywhere within 10 miles even, you can hear it rumbling in your ears and in your body.” No one heard rumbling, so they prepared to go right to the rim of the crater.
Their mission was to make a map of Kavachi’s peak and learn as much as possible about the chemical plumes, geology, and biology of the volcano. It is an extreme and dangerous environment.
Sensing Earth’s Inner Power
“Nobody actually knows how often Kavachi erupts,” says Phillips, referring to it actively “spewing hot lava, ash, and steam up in to the air.”
Even without such theatrics it’s a dangerous place. “Divers who have gotten close to the outer edge of the volcano have had to back away because of how hot it is or because they were getting mild skin burns from the acid water.”
So the team strategically deployed their instruments—including disposable robots, underwater cameras, and National Geographic’s deep-sea Drop Cam—to get a broad look at the whole volcano, including what the bottom looks like. Their biggest surprise was that hammerheads and silky sharks showed up on their deep-sea Drop Cam footage—in numbers (Related story: Sleeper Shark Pops Up in Unexpected Place).
How Do They Survive?
“These large animals are living in what you have to assume is much hotter and much more acidic water, and they’re just hanging out,” Phillips says. “It makes you question what type of extreme environment these animals are adapted to. What sort of changes have they undergone? Are there only certain animals that can withstand it? It is so black and white when you see a human being not able to get anywhere near where these sharks are able to go.”
Despite the fact that Kavachi was not actively erupting, the video shows carbon dioxide and methane gas bubbles rising from the seafloor vents, and the water appearing in different colors due to reduced iron and sulfur.
Phillips is keen to set up a seismic observatory along with long-term deployment of deep-sea cameras on Kavachi. “It would be very interesting to pair observations of animal activity, such as the sharks, with actual eruptions of the main peak. Do they get an early warning and escape the caldera before it gets explosive, or do they get trapped and perish in steam and lava?”
“It opens up all kinds of questions … There are infinite directions in which we can go.”
Read About Brennan Phillips’ other big discovery on this expedition: Sleeper Shark Pops Up in Unexpected Place.