Americans live on the tectonic plate known as the North American plate. According to Plate Tectonics theory, the world is comprised of 15 major tectonic plates.
Plate Tectonics theorists say the North American plate moves to the west-southwest at about
2.3 cm, or about 1 inch, per year. The Juan De Fuca plate moves north-northeast at about 4 cm, or about 1.6 inches, per year and is currently subducting beneath the North American plate.
The sticky subduction of the Juan De Fuca plate beneath North America is responsible for most seismic and volcanic activity in California and the Pacific Northwest.