hot spot

In earth science, area where a strong current or ‘plume’ of magma rises upwards below the Earth's crust. The magma spreads horizontally in all directions, and may break through where the crust is thin. Hot spots occur within, rather than on the edges of, lithospheric plates. However, the magma usually reaches the surface at plate margins. Examples of hot spots include Hawaii, Iceland, and Yellowstone National Park, Wyoming, USA.

Chains of volcanoes trace the movements of plates as they pass over hot spots. Immediately above a hot spot on the oceanic crust a volcano will form. This volcano is then carried away by plate tectonic movement, and becomes extinct. A new volcano forms beside it, again above the hot spot. The result is an active volcano and a chain of increasingly old and eroded extinct volcanoes stretching away along the line traced by the plate movement. The chain of volcanoes comprising the Hawaiian Islands and Emperor Seamounts formed in this way.