The mystery of Bermuda’s long-hidden subterranean tunnels is revealed.
Bermuda has been a mystery to scientists for many decades. The mantle plume is usually fueled by hot rock under a plate tectonics. This lumpy upwelling causes a series of volcanic eruptions, as well as a larger topographic rise on the ocean bottom, which can be up to 500km.
They are usually associated with volcanism.
Bermuda, however, is unusual: it has no volcanic or mantle plume beneath its surface. The seabed surrounding Bermuda, however, is high for some strange reason.
A new study has revealed a deeper mystery literally under the islands.
Scientists discovered Bermuda stands on an unusual foundation. According to research conducted by William Frazer of Carnegie Science and Jeffrey Park at Yale, Bermuda rests on an unusual geological base. Bermuda’s unique geological foundation, which is a result of a research led by William Frazer from Carnegie Science and Jeffrey Park from Yale, keeps it rising out of the Atlantic despite its last volcano eruption millions years ago.
Mantle plumes are hot columns of rock that rise from deep within the Earth. The plumes are what feed the volcanoes, and they lift the seafloor to form a dome. As tectonic plate shifts and volcanic eruptions cease, the dome is usually displaced.
Bermuda is an exception to this rule.
Over 30 million years have passed since the last eruption of its volcanoes, but today there is no mantle. The island is actually situated on an enormous uplift that rises nearly 1600 feet over the seabed.
Scientists struggled for years to explain why Bermuda was so high without resorting the normal explanations such as heat and buoyant pressure.
Bermuda’s long-hidden mysteries are being uncovered
Scientists say they analyzed seismic waves that traveled through Bermuda’s Earth caused by earthquakes. These waves are similar to the sound that changes pitch depending whether it’s moving through water, air or metal. They also speed up or slower depending on what material they travel through.
A seismic station was installed on the island, and the team produced an image showing the Earth’s innermost layers down to approximately 20 miles beneath the surface.
They found a layer of rocks more than 12 miles in thickness, just beneath the crust. The rock around it is much lighter, which makes it buoyant. This lighter rock, instead of being pushed up by a plume from beneath, acts as a giant boat, lifting the island and the seafloor above the Atlantic.
Scientists think Bermuda’s “raft” was formed by volcanic activity millions of years before. Carbon-rich, molten rocks from the depths of Earth were squeezed down into the crust, cooled and left behind a thick, underplating.
This material could have roots dating back to Pangea, hundreds of millions years ago.
William Frazer searches for similar geological structures beneath other islands. Bermuda may be an anomaly, and still have geological significance, but it won’t be anything special. If not, then who knows?
This example, in either case, highlights the importance and necessity of using seismic imaging to study geological formations which defy current models.
The geology of Bermuda is unique, as it does not fit into the typical plume model. Frazer explains. We observe a thick underplating that we don’t see in most plumes of mantle. This, along with geochemical data from recent years, suggests that there are still many convective processes in Earth’s Mantle which remain unexplored.
Journal Reference
- William D. Frazer, Jeffrey Park. The Bermuda Swell: Thick Underplating, Buoyancy and the Bermuda Swell. Geophysical Research Letters.
DOI: 10.1029/2025GL118279
