Scientists have solved a long-standing geological mystery: why Bermuda has remained above the ocean surface for millions of years after its volcanoes became extinct. The answer lies in a massive hidden layer of lighter rock buried deep beneath the island.
Normally, volcanic islands gradually sink once their volcanic activity ceases. Bermuda's volcanoes stopped erupting over 30 million years ago, so the island should have subsided long ago. Instead, it remains unusually elevated above the surrounding sea floor.
Researchers William Frazer and Jeffrey Park used 23 years of earthquake recordings from a single seismic station to map rock layers over 25 miles beneath Bermuda. They discovered a 12-mile-thick slab of lighter volcanic rock, which is about 1.5% less dense than the surrounding mantle, providing buoyancy.
The slab formed 30–35 million years ago when molten material rose, spread beneath the crust, and cooled. This buoyancy explains the Bermuda Rise, an underwater plateau standing 1,300–3,300 feet higher than adjacent crust. The study was published in Geophysical Research Letters.
