New Zealand Is Sitting on Top of a Massive Bubble of Lava From an Ancient Volcano

About 120 million years ago, a vast, unbroken volcanic plateau formed beneath the sea. verticalberto/Shutterstock

Scientists may have found the most compelling evidence yet that the Earth's molten core belches out blobs of lava that eventually find their way to the surface.

In fact, the evidence is hard to ignore. It’s New Zealand.

In a study published in Science Advances, researchers from the Victoria University of Wellington suggest the country is perched on a vast bubble of lava produced by an ancient volcano.

Now, if you’re in New Zealand, there’s no reason to panic. Or even tread lightly. That lava has had more than 100 million years to cool and harden. In fact, as the researchers point out, those ancient volcanic eruptions likely created an undersea plateau during the Cretaceous Period. That India-sized plateau eventually fragmented, with a big chunk becoming the box spring for New Zealand. That lava-cooled slab would become known as the Hikurangi Plateau.

“Our results show that New Zealand sits atop the remains of such an ancient giant volcanic plume,” the researchers explain in The Conversation. “We show how this process causes volcanic activity and plays a key role in the workings of the planet.”

Sitting atop a powerful force

Their research paints a fascinating picture of the heavy forge at the heart of our planet. There’s a long-standing theory that the Earth’s interior churns “like a lava lamp, with buoyant blobs rising as plumes of hot mantle rock from near Earth's core,” the researchers note in the article.

As those plumes creep toward the surface, the theory suggests, they melt — and volcanic eruptions ensue. But evidence supporting that theory was scant — until scientists took a closer look at New Zealand’s underpinnings.

Specifically, they measured the speed of seismic pressure waves moving through rocks beneath the Hikurangi Plateau. Those waves, known as P-waves, are essentially sound waves. And they move at a consistent and measurable speed through the planet’s roiling interior. But they move more slowly when travelling vertically outward, as opposed to horizontally in every direction.

That speed difference helped researchers determine the staggering scope of the superplume beneath New Zealand. The research also hints at the even more vast, unbroken plateau that once stretched beneath the sea.

"The extraordinary thing is that all these plateaus were once connected, making up the largest volcanic outpouring on the planet in a region over 2,000 km across,” the researchers note. "The associated volcanic activity may have played an important role in Earth history, influencing the planet's climate and also the evolution of life by triggering mass extinctions.

"It is an intriguing thought that New Zealand now sits on top of what was once such a powerful force in the Earth."