Geophysics is the study of the substances that make up the Earth and the physical processes occurring on, in and above it. Information derived from altimetry data can be used to study tectonic plate motion, rifts, etc.

Plate Tectonics

Gravity anomalies (top) in the North Atlantic measured in milligals (1 mGal = 10-5 m/s²). Since gravity depends on distribution and density of material, features such as the Mid-Atlantic Ridge and fracture zones show up clearly.
(Credits Legos)

Further information:

Cazenave, A. and J.Y. Royer, Applications to marine geophysics, Satellite altimetry and Earth sciences, L.L. Fu and A. Cazenave Ed., Academic Press, 2001