Most of the Earth's volcanoes occur in areas where oceanic plates are subducting beneath other tectonic plates; this is especially common throughout the Pacific Rim (the Andes, Cascades, Aleutians and Indonesian islands are all volcanic). They also occur along the oceanic ridges, in continental rift zones and at "hot spots."
The latter are areas where mantle plumes are melting the deep basement rocks of the oceanic and continental plates, producing pockets of magma. This liquified rock reaches the surface as volcanic formations. Yellowstone National Park, the Galapagos Islands and the Hawaiian Islands are all examples of hot spots. In the case of Hawaii, the Pacific plate has been moving northwestward over the hot spot, resulting in a chain of 20 islands and atolls. The big island of Hawaii is now over this mantle plume and is thus the site of active volcanic activity.
Recent scientific evidence suggests that these hot spots are not stationary features and have moved about through geologic time. Perhaps one will develop in your neighborhood!
