High School Earth Science: Volcanoes - Where Volcanoes Are Located — Flashcards

Volcanic Hotspots    
Most volcanoes are found at convergent or divergent plate boundaries, but there are some intraplate volcanoes. The   
Hawaiian Islands are examples. The islands are the exposed peaks of a great chain of volcanoes that lie in the middle of the Pacific plate. The youngest of the Hawaiian Islands sits directly above a column of hot rock called a mantle plume. As the plume rises through the mantle, pressure is released and mantle melts to create a hotspot. All of the  Hawaiian Islands are hotspot volcanoes.    
Earth is home to about 50 known hotspots. Most of them are in the oceans because magma can more easily penetrate oceanic than continental lithosphere. The hotspots that are known beneath continents are extremely large. For example, a huge hotspot is located beneath the Yellowstone volcano on the North American continent.    
As a plate drifts over a mantle plume, a hotspot volcano slowly moves away from the hotspot. Then a new hotspot volcano forms. This keeps repeating as the plate continues to drift, forming a chain of hotspot volcanoes. The youngest volcano in the chain is always at the start of the chain, directly over the mantle plume. Each volcano after that is older than the one before it, with the oldest volcano at the opposite end of the chain.