A hotspot is a small, long-lived, very hot region beneath the Earth's plates that feeds volcanoes. As a plate moves over a hotspot, it carries each volcano away and a new one forms, leaving a trail of islands and undersea mountains.
Key takeaways
- Hotspots are small hot regions beneath the plates, mostly found in plate interiors, not along plate edges.
- When a plate moves over a hotspot, it leaves a line of volcanoes that gets older away from the active one.
- Kamaʻehuakanaloa Seamount, at the young end of the Hawaiian chain, has a summit 1,033 m below the surface in our grid.
- Newer studies suggest hotspots may not be fixed or very deep, so the classic fixed-plume model is disputed.
How a hotspot works
Most volcanoes form at the edges of plates. Hotspots are different. USGS describes them as small, long-lived, very hot regions beneath the plates that supply heat for volcanism, with more than a hundred having been active in the past 10 million years, mostly in plate interiors [1].
The classic explanation comes from J. Tuzo Wilson, who proposed that the line of the Hawaiian-Emperor chain comes from the Pacific Plate moving over a deep, stationary hotspot, now beneath the island of Hawaii [1]. As the plate moves, each volcano is carried away from the magma source and goes extinct, and a new volcano forms over the hotspot. The result is a trail of islands and seamounts [1].
The trail records the plate's movement. Along the chain, the islands get younger towards the active end. On Kauai, the oldest rocks are about 5.5 million years old and deeply eroded, while on the island of Hawaii the oldest exposed rocks are under 0.7 million years old and new rock is still forming [1].
The picture has a caveat. USGS notes that newer studies suggest hotspots are neither deep nor fixed over long spans of geological time, which challenges the fixed-plume model [1]. For a map reader, the useful part is the pattern: a long, roughly straight line of volcanoes in the middle of a plate, getting older along one direction.
When a volcano in the chain is carried far from the hotspot, it stops erupting, the seabed beneath it cools and sinks, and what is left is an extinct volcano on the ocean floor. Many are seamounts, and some became flat-topped guyots.
An example from our data
Kamaʻehuakanaloa Seamount has a summit 1,033 m below the surface in the grid, 33 km from the coast of the United States of America in our data. It lies off the island of Hawaii, at the young end of the chain.
The older end of the trail continues north-west across the Pacific as the Emperor Seamounts. Suiko Seamount has a summit 942 m down. Meiji Seamount is 3,009 m, 224 km from Russia, and Detroit Seamount is 1,487 m. Each is a volcano that once sat over the hotspot and was carried away.
Our list holds 420 named seamounts in all. The map does not mark which seamounts belong to which chain, so use the feature pages. The homepage explains how to read the colours.
The thing people get wrong
People often think hotspots sit at plate boundaries, like most volcanoes. In fact most hotspots are in the middle of plates [1]. Volcanic island arcs, by contrast, form along subduction zones, curve around a trench, and sit at a plate boundary [2].
A second mistake is to treat the fixed-hotspot model as settled. The straight, ageing chain is solid evidence of a moving plate over a long-lived source, but how deep the source is and whether it stays put are both debated [1].
Hotspot vs volcanic island arc
Frequently asked questions
Where is the Hawaiian hotspot?
J. Tuzo Wilson proposed that the Hawaiian chain comes from the Pacific Plate moving over a deep, stationary hotspot now beneath the island of Hawaii. USGS notes that this idea is now debated.
Are all volcanic islands from hotspots?
No. Many form along subduction zones in volcanic island arcs, which are curved chains beside deep ocean trenches.
Sources
- Hotspots, USGS (This Dynamic Earth).
- Understanding plate motions, USGS (This Dynamic Earth).
- Every figure from our own map is worked out from the datasets on the data sources page (checked against GEBCO_2026 grid).