Analyzing Plate Motion Using EarthScope GPS Data

In this chapter, users access GPS data from the Plate Boundary Observatory (PBO); they analyze the data in a spreadsheet to measure the motion of GPS stations in the Pacific Northwest. From their analyses, users generate and map annual velocity vectors of GPS stations. Finally, they explore patterns in the direction and length of velocity vectors on the map to understand tectonic motion and surface deformation associated with the subduction of the Juan de Fuca plate under the North American plate.

From an easy-to-use map interface, users access information about GPS stations and the data they collect. They learn about the network of GPS monuments and how position data collected at these sites are analyzed to reveal plate motion. The activity provides complete instructions for calculating north-south and east-west velocity vectors for a GPS station and combining them to produce a vector that represents the annual horizontal motion of the station. Users plot velocity vectors on a map and examine the pattern of direction and lengths. With first-hand experience in producing and mapping station velocity vectors, users are better prepared to use the patterns of velocity vectors and earthquake distributions to interpret regional geology.