So I vaguely remember hearing about the “sharkcano” once before, but I definitely needed a refresher. It’s an underwater volcano in the Solomon Islands, and in 2015 it was discovered that there were a number of sharks and other fish living in the crater of the volcano, where the water is both hot and acidic. We’re talking temperatures of 40°C/104°F or higher, if I’m reading this paper right. Long-time readers will know that one of the concerns with a warming climate is that hotter water can hold less dissolved oxygen, meaning some fish – especially the larger, more active ones – will have to find cooler water, or suffocate. From what I can tell, the fact that the crater is near the surface, and there’s a lot of thermal activity there, means that the water mixes around more than usual, so I’d guess that that raises the oxygen level. I suppose it’s also possible that the fish there somehow need less oxygen? I really don’t know. Regardless, I hope the sharks and everyone else living there knew their home well enough to flee, because it has erupted. I honestly expect that they’ll be OK, because this isn’t the first time.
Named after a sea god of the Indigenous Gatokae and Vangunu people, Kavachi is located about 15 miles south of Vangunu Island, part of the Solomon Islands east of Papua New Guinea. It’s one of the most active underwater volcanoes in this part of the Pacific and has been erupting nearly continuously since at least 1939, when people living on nearby islands first recorded an eruption, according to the Smithsonian’s National Museum of Natural History Global Volcanism Program.
The volcano is also known by the name Rejo te Kvachi, which means “Kavachi’s Oven”—a fitting moniker for the superheated lava, steam, particulates, rock fragments and sulfur that sometimes reach the water’s surface. Scientists believe the volcano’s summit is roughly 65 feet below the water; Kavachi’s base is on the seafloor, about three-fourths of a mile below sea level, per NASA.
Over its recorded history, Kavachi has created a handful of ephemeral islands that have spanned up to a kilometer in length. But the ocean’s waves have always eroded and washed these islands away. It also produces dramatic phreatomagmatic eruptions, in which superheated magma and water interact to create violent, steamy explosions.
“Sharkcano” earned its nickname after a 2015 expedition found two species of sharks, along with active microbial communities, living within the volcano’s crater. Using a baited drop camera, an international team observed scalloped hammerhead sharks (Sphyrna lewini) and silky sharks (Carcharhinus falciformis) living in the hot, acidic water. Kavachi is a “fascinating natural laboratory” that “remains full of mysteries to explore,” according to the researchers, who published the results of their exploration in the journal Oceanography in 2016. NASA has been tracking Kavachi for some time, taking equally spectacular photos of eruptions in 2007 and 2014.
When I played Subnautica, I thought that the “lava lizards” that lived in and around underwater volcanoes were pretty far-fetched as life forms went, but this is honestly closer to that than I realized could exist. The 2015 paper I linked above points out that higher temperatures and higher acidity are both major concerns for the survival of life in the ocean in the coming years. Last year’s heat wave killed hundreds of millions of sea creatures on the west coast of North America, and I think it’s fair to say we’re going to see more of that. It’s nice to know that life – even life that’s familiar to us – is possible even in an acidic stew like that.
Even so, I think I’ll keep trying to prevent those conditions from becoming commonplace around the world.
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