Why does Bermuda appear to float? Scientists' discovery may be the answer
Seismologists have made a fascinating discovery about what lies beneath the Bermuda -- a never-before-seen plume of rock that makes the archipelago appear to float in the middle of the ocean, according to a paper published last month in Geophysical Research Letters.
Typically, volcanic islands are buoyed by magma plumes, which push the crust of the Earth up. But in the case of Bermuda, the volcanoes that underpinned it have not been active for millions of years.
The mass measures more than 12 miles thick but is less dense than the other layers of rock surrounding it -- oceanic crust above it and the upper mantle below it, according to the paper. The structure's thickness has never been seen anywhere else in the world for islands in the middle of a tectonic plate, the researchers said.
The researchers used recordings of large earthquakes around the world from a seismic station in Bermuda to get an image of Earth's layers about 31 miles below Bermuda. Analysis of places where seismic waves suddenly changed revealed the thick layer of rock.
Typically, what is layered below the oceanic crust is a rigid upper mantle -- the outermost rocky shell. But below Bermuda, a unique layer has developed between the upper mantle and the oceanic crust but within the tectonic plate that the islands sit above, according to the paper.
Its existence may explain why Bermuda did not sink after its volcanoes shut down tens of millions of years ago, according to the paper.
The last major eruption occurred in Bermuda about 30 million years ago, during which mantle rock may have been injected into the crust.
When the new layer solidified, it created a raft-like structure that raised the ocean floor by more than 1,600 feet, according to the paper.
