Overview
- The layer sits between the oceanic crust and upper mantle, is about 1.5% less dense than surrounding rock, and provides long‑lived buoyant support without present‑day heat flow.
- Researchers used records from Bermuda’s permanent seismic station to image distinct interfaces by tracking wave reflections and travel times.
- The team interprets the feature as magmatic underplating emplaced roughly 30–35 million years ago, offering an alternative to a deep mantle plume to account for the swell.
- Authors estimate the structure could extend 50–100 kilometers from Bermuda, with about 200 kilometers cited as an extreme upper limit, potentially keeping the seafloor elevated by roughly 500 meters.
- The peer‑reviewed findings, published in Geophysical Research Letters, leave open questions on origin, composition, and global prevalence, with broader surveys and sampling proposed.