Measuring Ground Motion with GPS: How GPS Works part of Geodesy:Activities
Shelley E Olds, EarthScope Consortium
With printouts of typical GPS velocity vectors found near different tectonic boundaries and models of a GPS station, demonstrate how GPS work to measure ground motion.GPS velocity vectors point in the direction that a GPS station moves as the ground it is anchored to moves. The length of a velocity vector corresponds to the rate of motion. GPS velocity vectors thus provide useful information for how Earth's crust deforms in different tectonic settings.

Converging Tectonic Plates Demonstration part of Geodesy:Activities
Shelley E Olds, EarthScope Consortium
During this demo, participants use springs and a map of the Pacific Northwest with GPS vectors to investigate the stresses and surface expression of subduction zones, specifically the Juan de Fuca plate diving beneath the North American plate.

Pinpointing Location with GPS Demonstration: How GPS Works (Part 2) part of Geodesy:Activities
Shelley E Olds, EarthScope Consortium
Using string, bubble gum, and a model of a GPS station, demonstrate how GPS work to pinpoint a location on Earth.Precisely knowing a location on Earth is useful because our Earth's surface is constantly changing from earthquakes, volcanic eruptions, tectonic plate motion, landslides, and more. Thus, scientists can use positions determined with GPS to study all these Earth processes.