Which area of the continental United States is most likely to experience the highest frequency of earthquakes?

• A. Midwest states along the Mississippi and Missouri rivers
• B. West Coast states including California
• C. Southeast coastal plain
• D. Great Plains

Answer: (B)

Earthquakes occur most often where tectonic plates interact, causing rocks to slip, break, or be forced up and down. The West Coast sits right on the boundary between the Pacific Plate and the North American Plate, including the San Andreas transform boundary and nearby subduction zones. This setup continually pushes and shoves rocks, producing frequent earthquakes, often felt across large areas. Regions inland, like the Midwest and Great Plains, lie far from major plate boundaries, so their crust is comparatively stable and experiences earthquakes far less often. The Southeast coastal plain is also away from the main plate interfaces, leading to even fewer seismic events relative to the West Coast.