The island is seven separate shield volcanos that erupted more or less one at a time, one partly covering the other. These are (from oldest to youngest): Kohala (extinct), Mauna Kea (dormant), Hualalai (dormant), Mauna Loa (active), Kulani (extinct, mostly buried), and Kilauea (very active). The volcanos were caused by the Pacific oceanic tectonic plate moving over a hotspot. There lava from the Earth's lower mantle or upper core is close to the surface.