Submerged islands are rising out of a molten lava lake in Hawaii, mystifying experts

It’s one of nature’s oddities that islands can float in a lake of molten lava, but that’s not the strangest part of what’s going on inside Hawaii’s erupting Kilauea volcano.

Rather than forming atop the lake as lava cools, the islands are actually emerging from it — like primordial turf rising from the center of the Earth.

The U.S. Geological Survey made the discovery using a thermal cameras stationed at the rim of the volcano, which is currently experiencing its second eruption since December 2020. (That eruption lasted five months.)

“It seemed apparent that the newly forming lava lake was going to continue rising and eventually cover all remnant topography of the earlier eruption,” the USGS reported Oct. 7.

“However, as the eruption progressed ... islands that geologists saw being submerged in new lava soon also started to reappear. ... It’s unclear why these islands — or rafts — that were only a few days ago submerged by the lava lake have reappeared.”

Their best guess: The islands, which formed during the 2020 eruption, are “buoyant in a way that is allowing for it to gradually float up within the new molten lava.”

Stranger still, this has resulted in a lava lake “current” that is vertical rather than horizontal, which drives the islands upward, the USGS says.

The largest of the islands has risen nearly 70 feet above the lake, which experts believe is deep enough to accommodate a 70-story building.

“It seems unlikely that these are individual pieces of crust detaching from the old, solidified lava lake floor and rising up,” experts say.

“If that were the case, at least some of the smaller island would then migrate around the lava lake as lava flows moving outward from the active vents push them around. All of the islands appear to be stationary except for floating vertically upward so it’s likely that all or large chunks of the older lava lake floor are moving upward together.”

The same phenomenon was observed nearly a century ago in the volcano’s crater, but on a much smaller scale, the USGS says. At that time, the crater was one-fifth of its current size, officials say.

This story was originally published October 11, 2021 at 6:23 AM with the headline "Submerged islands are rising out of a molten lava lake in Hawaii, mystifying experts."