Mysterious Appalachian Mountains have a hidden 'blob' where earthquakes happen slower than rest of the world

Another strange anomaly from beneath the Earth has scientists baffled, with the Northern Appalachian Anomaly (NAA) supposedly creeping toward New York City.

Described as a giant 'blob' that spans 350 kilometers, the NAA is "a large region of unusually hot rock deep beneath the Appalachian Mountains."

Working a bit like the droplets coming off a lava lamp, the NAA is part of a 'mantle wave' that's formed when hot, dense rock peels away from the base of tectonic plates. The humungous blob is coming toward New York, but thankfully, it won't get there for another 15 million years.

In new research conducted by the Southampton and the Helmholtz Center for Geosciences (published in Geology), both worked together to postulate that the NAA was formed when Greenland and North America split apart 80 million years ago.

Previously, many thought it was caused by plate tectonic movements when North America broke from Northwest Africa some 180 million years ago.

The NAA is located near a deep geological structure that was created by the Laramide Orogeny.

What is the Northern Appalachian Anomaly?

Scientists are lifting the lid on the NAA (University of Southampton)

Around 1.5 million years ago, the Laramide Orogeny was active as the Earth's crust was folded to form massive mountain ranges like the Rockies while leaving a thicker layer of crust in the east of the USA.

Lead author Tom Gernon explains: "This thermal upwelling has long been a puzzling feature of North American geology.

Hyptohecizing that the NAA was formed by Rayleigh-Taylor instability, which is where mantle becomes unstable due to the breakup of ancient tectonic plates.

Gernon continue: "It lies beneath part of the continent that's been tectonically quiet for 180 million years, so the idea it was just a leftover from when the landmass broke apart never quite stacked up."

Although some maintained that the east of the US is a 'geologically dead' area, suggest that the similar Central Appalachian Anomaly (CAA) to the south might've also shaped America's mountain regions millions of years ago.

Gernon added: "The 'mantle wave' refers to a newly-discovered chain reaction of convective instabilities in the mantle that begins when a continent starts to rift."

How was the Northern Appalachian Anomaly formed?

More drips could form under some of America's major mountain ranges (Marcia Straub / Getty)

The 'drip' of denser materials sink into the mantle while the lighter and hotter rock rises to form blobs. Importantly, earthquakes move slower in these anomalies due to the less dense.

It's thought that the 'blob' is the reason there are fewer earthquakes in the Northeast thanks to the mantle cushioning tectonic stress and helping prevent breaks in the crust.

Still, geologists remind us that the crux of the regions stability comes from the thick crust that was formed many eons ago.

Speaking to Newsweek, Gernon concluded: "These 'drips' migrate inland over time, away from the rift. We think this same process might explain unusual seismic patterns beneath the Appalachians. The timing lines up perfectly."

Drips can trigger others, with the Central Appalachian Anomaly, like coming from an older drip that was formed in the chain 135 million years ago.

The process could still be active and new blobs could be created, although a seismic data from from the likes of Newfoundland make it hard to confirm whether are are any newer drips.