Why are volcanoes found in the united states?

Volcanoes are found in the United States for different reasons. Some are results of subduction zones. A subduction zone is a place where a piece of the Earth's oceanic crust slides under another into the mantle. The piece heats up and releases water which rises and lowers the melting point of hot mantle rock causing it to melt. The magma rises and collects under the surface. Once pressure from gas has become strong enough, magma, gas, and ash blasts through the surface. This is a volcanic eruption. Other volcanoes are a result of a hot spot. A hot spot is a place inside Earth where magma rises. Where it punches through the surface, there is a volcano. Other volcanoes are a result of a rift zone. A rift zone is a place where the Earth's crust is breaking apart. Where it has broken enough, magma rises through the break to the surface.