Bermuda's secret: A thick layer under the island explains its lasting "swell"
Scientists have discovered a massive, 20-kilometer-thick layer beneath Bermuda's ocean floor—similar to a hidden raft under the island.
This discovery finally explains why Bermuda has had its famous "swell" (a raised area in the seafloor) for millions of years.
How did they figure this out?
Researchers used earthquake waves recorded in Bermuda to peek deep underground.
What they saw was surprising: a thick, less-dense layer way bigger than what's found under most islands.
So, what caused it?
Turns out, about 31 million years ago, a huge volcanic event pushed up mantle material that froze into place beneath Bermuda.
This lifted the seafloor by about 500 meters and created the swell we see today—no need for an active volcano or hot plume underneath.
Why does this matter?
This shakes up old ideas about how islands like Bermuda form and last so long.
The study gives scientists a new way to tell if other islands are floating on similar hidden layers or just temporary hot spots.