Most volcanoes occur near the Earth's plate boundaries, but some do not. For example, the Hawaiian islands have been formed over millions of years by volcanic eruptions thousands of miles from the edges of the Pacific plate. Island formation is still happening on Hawaii every time the shield volcanoes Kilauea and Mauna Loa erupt.
It is thought that a hotspot - a stationary plume of magma that rises from deep within the Earth - powers the volcanism on Hawaii. As the Pacific plate slowly moves over the hotspot, the islands in the Hawaiian-Emperor chain have been built one at a time by a numerous volcanic eruptions.
Another hotspot is responsible for the past super-eruptions at Yellowstone National Park in the United States.
Image: Artwork showing a hotspot forming an island in the Hawaiian-Emperor chain (credit: Gary Hincks/SPL)
Scientists find evidence of a supervolcano's devastating power.
Archaeologists working in Orchard, Nebraska, found hundreds of fossilised prehistoric animals that were killed by ash from a volcanic eruption. When they traced the source of the ash, they discovered that it was a supervolcano 1,600km away in Bruneau Jarbridge, Idaho. The hotspot that powered the Bruneau Jarbridge eruption 12-10.5 million years ago caused a trail of prehistoric super-eruptions as the North American plate moved over it.
Lava flows from this spectacular volcano have built the island of Hawaii.
Professor Iain Stewart explains how Mount Kilauea's eruptions of lava have built up the island of Hawaii over millions of years as a magma plume known as a hotspot rises up through the Earth's crust.
Plate boundaries are places of chaos and mineral wealth.
Professor Iain Stewart explains how hotspots are a good demonstration of Earth's system of tectonic plates. As the plates move across the Earth's surface, they interact with one another at plate boundaries, which are places where earthquakes and volcanoes are common. Typically, plate boundaries are also places of great mineral wealth.
The places known as hotspots or hot spots in geology are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the mantle elsewhere. They may be unanimously hot, and provide a great deal of molten magma. They may be on, near to, or far from tectonic plate boundaries. There are two hypotheses to explain them. One suggests that they are due to hot mantle plumes that rise as thermal diapirs from the core-mantle boundary. The other hypothesis postulates that it is not high temperature that causes the volcanism, but lithospheric extension that permits the passive rising of melt from shallow depths. This hypothesis considers the term "hotspot" to be a misnomer, asserting that the mantle source beneath them is, in fact, not anomalously hot at all. Well known examples include Hawaii and Yellowstone.