NASA's Role in Investigating Continental Drift

For example, SLR satellites show that the island of Maui, Hawaii, is moving northwest toward Japan at approximately 3 inches (7 cm) per year. Plate tectonic theory predicts motion in that direction of approximately 4 inches (9 cm) per year. Maui also is moving away from South America at approximately 3 inches (8 cm) per year, close to the 2 inches (6 cm) per year predicted by plate tectonics.

The Southern California Integrated GPS Network (SCIGN) is a group of connected GPS receivers which are used to monitor the build-up of strain along the two tectonic plates which are touching in southern California. This is done by measuring very small movements at faults that aren't usually noticeable.

SAR Interferometry results for the 1992 Landers, CA earthquake.

Synthetic Aperture Radars (SAR) produce all-weather, day and night, high quality pictures of the Earth's surface. By combining two or more pictures of the same area, it's possible to make maps that are highly detailed and show useful information about an area. This technique is called SAR interferometry. SAR interferometry has been applied to the study of earthquakes, volcanoes, glacier flow, landslides, and other geologic events.

All these techniques should lead to a better understanding of the occurrence of earthquakes at plate boundaries, vulcanism, and the cause of mountain building. It may eventually tell us if Wegener's theory of continental drift can be explained by plate tectonics.