Scientists discover a 220‑mile‑wide ‘hot blob’ beneath New Hampshire, drifting towards NYC

Deep beneath New Hampshire and the broader New England region, scientists have discovered a massive area of superheated rock known as the Northern Appalachian Anomaly (NAA), reveals a new study published in the journal Geology. This discovery, made through advanced seismic tomography — essentially a CT scan of the Earth — reveals a thermal anomaly about 124 miles (200 kilometers) beneath the surface.

The NAA is enormous, stretching roughly 350 to 400 kilometers wide within the asthenosphere, the semi-molten layer of the upper mantle. Its temperature is significantly higher than the surrounding rock, a finding that challenges previous assumptions about the region’s geological stability.

For decades, geologists believed the Appalachian Mountains were among the most stable mountain ranges on Earth, owing to their ancient origins. However, the presence of this hot blob suggests otherwise. Mantle heat beneath a continent can weaken and buoy up the crust, slowing erosion and even causing uplift over millions of years.


According to Professor Tom Gernon of the University of Southampton, this mechanism is akin to a hot air balloon rising after dropping ballast. Such heat, positioned deep beneath the Appalachians, may be one reason these mountains have remained prominent despite their age.

The origin of the Northern Appalachian Anomaly appears to date back 80 to 90 million years, when Greenland and North America began to separate — a much later tectonic event than the breakup of North America and Africa. Scientists believe the anomaly formed near what is now the Labrador Sea during this period. It is the product of a process known as Rayleigh–Taylor instability, in which denser, cooler rock sinks into the mantle while hotter material rises, much like the blobs in a lava lamp. Over time, this hot material has slowly migrated westward beneath the North American plate.

This migration is extremely gradual, moving at a rate of just 20 kilometers per million years. Current models project that in about 15 million years, the NAA could drift under the area beneath New York City. While this might sound alarming, geoscientists emphasize that the anomaly poses no direct or immediate risk to people or infrastructure. The changes it drives happen over geological timescales, imperceptible in human lifetimes.

The NAA’s discovery has major implications for our understanding of Earth’s interior. Most mantle anomalies are found near plate boundaries or volcanic regions, but this one lies deep within a stable continental interior. This mantle feature offers scientists a new framework for studying how old continental interiors can still be shaped by deep, slow-moving processes.

Ongoing research is focused on refining models of the NAA’s shape, composition, and movement, while also looking for similar anomalies elsewhere in the world.