Bermuda mystery may finally be solved as scientists reveal what's really hidden underneath
Niamh Shackleton
Featured Image Credit: Getty Stock Image
There's many mysteries that are linked to Bermuda, but one of them might have now been solved.
Researchers from Carnegie Institution for Science and Yale University have recently put their heads together to try work out why the island sits unusually high above the Atlantic Ocean, despite the fact that its volcanoes have been inactive for millions of years.
Typically a volcanic island needs ongoing volcanic activity to remain above water - Hawaii being one example. But those below the island of Bermuda – which is the top of an ancient underwater volcano system – died out over 30,000,000 years ago.
With this in mind, many expected it sink over time... but it hasn't.
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Now, with the help of two decades worth of earthquake recordings, researchers William Frazer and Jeffrey Park think they have pieced together the puzzle.
The data used was gathered from a single seismic monitoring station on Bermuda and allowed researchers to create a picture of Earth’s interior down to about 20 miles beneath the island.
Frazer and Park investigated the vibrations produced by distant earthquakes. This played a key part in their discovery as seismic waves move differently depending on the density and composition of underground rock layers.
The discovery? That Bermuda, which is home to more than 60,000 people, has a giant slab of rock that sits just below the oceanic crust that helps keep it afloat.
The researchers estimate that the slab is 12 miles in thickness and is approximately 1.5 percent less dense than the surrounding mantle material, therefore making it more buoyant.
This slab is thought to have been formed 30 to 35 million years ago when carbon-rich molten mantle rock intruded into the base of the crust and cooled in place. This is something known as 'underplating'.
Frazer and Park wrote in their study conclusion: "The deepest layer is ∼20 km thick and likely formed during or soon after the volcanism that formed Bermuda.
"We interpret this layer to be underplating that could extend 50–100 km out from the center of the swell. If this underplated layer is positively buoyant relative to the mantle, it can support the swell."
Now Frazer is looking into the idea that other islands across the globe might have giant floating slabs below them as well.
Discussing his recent discovery, Frazer said (per the Carnegie Institution): "Bermuda is an exciting place to study because a variety of its geologic features do not fit the model of a mantle plume, the classic way for deep material to be brought to the surface.
"We observe thick underplating, something that is not observed at most mantle plumes. Combined with recent geochemical observations, this suggests that there are other convective processes within Earth’s mantle that have yet to be well understood."