![]() The youngest, active volcanoes are located within a region of the plate that overlies the mantle plume. Over geologic time, these processes produce lines of islands, atolls, and seamounts known as hotspot tracks, or chains. Eventually the hotspot volcanoes become extinct, gradually subside, and are eroded by wave action. As hotspot volcanoes are transported by plate motion away from the mantle plume, hotspot volcanism ceases. Thus, as a plate moves over the location of a plume eruption, it carries successively older volcanoes with it. Mantle plumes that form hotspots are thought to be relatively stationary whereas the overlying tectonic plates typically are not. Hotspot volcanism is distinct in that it does not originate from processes that produce the more common submarine volcanism that occurs at boundaries of Earth’s tectonic plates. When such a plume rises into the shallow mantle, it partially melts and the melt may then rise to the surface where it can erupt as a hotspot volcano. In much the same way that plumes rise buoyantly in a lava lamp, plumes of mantle magma (molten rock) are theorized to rise buoyantly from a source within Earth’s deep mantle. Figure made with assistance from Drew Reinhard. Samoa is an example of one of at least 28 plume-fed volcanic hotspots are suggested to exist on the Earth’s surface. Samoa is composed of a linear chain of volcanic islands situated atop the Pacific tectonic plate.
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