New Zealand's Hikurangi Plateau was once part of a gargantuan volcanic mountain that covered 1% of Earth's surface.

In a study published May 27 in the journal Science Advances, researchers measured the speed of seismic waves traveling through a layer of Earth called the mantle that sits between the planet's crust and outer core.

They focused on Hikurangi Plateau — a vast, triangle-shaped chunk of volcanic rock located about 2,000 miles (3,200 kilometers) beneath the top of the South Pacific Ocean, just off the coast of New Zealand's North Island.

The team found a match between the seismic waves traveling through that chunk and those traveling through two other nearby volcanic structures. .

According to Stern, mantle plumes form when huge "lava lamp blobs" of hot, buoyant rock break away from the boundary where Earth's mantle meets the outer core, then rise thousands of miles up toward the surface.

To test that theory, the team measured the speed of seismic waves traveling under Hikurangi!

Using data obtained from earthquakes and controlled undersea explosions, the team found that seismic waves traveled horizontally through the rocks at nearly 6 miles per second (9 km/s), roughly a mile per second faster than the average global speed at which seismic waves travel through the mantle.

Strangely, though, seismic waves moved much more slowly when traveling vertically upwards beneath the plateau.

Hopefully, Stern added, the strange seismic wave speed signature linking these three plateaus could be used as a "fingerprint" to identify other scattered fragments of the once-giant superplume.