What do you call a massive underground magma chamber that has no volcano on the surface above it. If you said, “Who cares what you call it … run!”, you may be right. Scientists in New Zealand are referring to a newly-discovered, unexpected magma chamber as a “zombie volcano” because it’s alive when it should be dead and is not where it’s supposed to be. Is this zombie getting ready to rise up out of the ground and trigger a volcanic apocalypse?

There’s no need to panic, but chances are there are lots of bodies of magma dotted throughout the crust.

That not-so-reassuring advice comes from a report in Scientific Advances by a team led by geophysicist Ian Hamling from GNS Science in New Zealand that was using satellite radar data to study the Taupo Volcanic Zone, a region in the center of New Zealand’s North Island that has seen major volcanoes over millions of years and sports many non-zombie but still unusual seismic features such as the geysers and hot mud pools in Rotorua. Their research of the Taupo Zone uncovered something they’d never seen before.

Map showing the Taupo Volcanic Zone (left) and the areas where the ground is rising instead of falling (right)

While most volcanic areas sink as the volcano erupts and the magna drains from the chamber under it, Hamling’s team found a spot along the Bay of Plenty coast not under a volcano that had been rising at a rate of between 5 and 12 millimeters per year since the 1950s. At the high end, calculations determined that 9 million cubic meters of magma was pushing the crust up from a chamber 10 km (6.2 miles) beneath the surface. Is that enough to be worried about? Hamling describes it:

When you compare it to other places, like Yellowstone, we’re smaller than that. But it’s still pretty significant.

Illustration of Zombie volcano under the Taupo Volcanic Zone

Do the 100,000 residents of nearby Tauranga (50 km/31 miles away) have a reason to fear this zombie? Hamling isn’t too concerned because the chamber is 6 miles deep. Elaine Smid, a volcanologist at the University of Auckland, suggests they should have thought of that before moving to such a high volcano area to begin with. And Matthew Pritchard, a geophysicist at Cornell University in New York who coined the phrase “zombie volcanoes,” is suddenly evasive.

Not to be too glib, but we are not undergoing a zombie-volcano invasion.

Pritchard says that the discovery of this and other zombie volcanoes or non-volcano magma chambers is just the result of researchers having better data from radar satellites to observe ground movements.

Tell that to the people living above a zombie volcano that’s not as big as Yellowstone but “still pretty significant.”

Not to be too glib, but doesn’t this remind you of a movie?