Core Concept: Seismic tomography uses earthquake waves to probe the inner Earth

Sid Perkins

Computerized tomography (CT) scans revolutionized medicine by giving doctors and diagnosticians the ability to visualize tissues deep within the body in three dimensions. In recent years, a different sort of imaging technique has done the same for geophysicists. Seismic tomography allows them to detect and depict subterranean features.

Data gathered by a network of seismic instruments (red) have enabled researchers to discern a region of relatively cold, stiff rock (shades of green and blue) beneath eastern North America. This is likely to be the remnants of an ancient tectonic plate. Image credit: Suzan van der Lee (Northwestern University, Evanston, IL).