How do hotspot volcanoes like Hawaii form far from plate boundaries?

Unlike volcanoes at plate boundaries, hotspot volcanoes can appear in the middle of tectonic plates. A stationary source of heat in the mantle melts rock, producing magma that rises through the crust. As the plate moves, the active volcano shifts off the hotspot and a new one forms above it. The Hawaiian-Emperor seamount chain records this process over tens of millions of years. Yellowstone in the United States is another famous hotspot region, though its volcanic system is much more complex than Hawaii's.