Measuring Ground Motion with GPS: How GPS Works

Tuesday 1:30pm-2:40pm
Share-a-thon Part of Tuesday


Beth Pratt-Sitaula, Earthscope Consortium
Shelley E Olds, EarthScope Consortium


I will bring examples of the vector printouts and "gumdrop" GPS stations. I will also bring examples of a couple other hands-on activities related to plate tectonics and earthquakes from EarthScope resource collections.


This activity helps students better understand how GPS measures ground motion. Students work with models of GPS stations and printouts of typical GPS velocity vectors found near different tectonic boundaries.

Students learn that GPS velocity vectors point in the direction that a GPS station moves as the ground it is anchored to moves. They see how the length of a velocity vector corresponds to the rate of motion and that GPS velocity vectors thus provide useful information about how Earth's crust deforms in different tectonic settings. They then apply this general understanding of reading vectors to interpreting plate motions in western North America.


This activity can be used with middle school, high school, and introductory undergraduate students, as well as free-choice learning environments.

Why It Works

This activity provides a real-world example of how vectors can be used --> to understand plate tectonics motions. It also allows educators to connect between everyday devices (i.e. GPS in smart phones) with scientific instruments (i.e. GPS/GNSS stations).