Science Spotlight

Station P393

P393, in eastern Oregon, is equipped with real-time data transfer capabilities.

State: OR
Country: United States
Elevation: 1238.9 m
Lat/Long:  43.2345 / -117.892

Eastern Oregon

P393 is moving relatively slowly compared to sites in western Oregon, like P405. While P405 is being dragged rapidly to the northeast, P393 is moving very slowly to the west. This difference shows that the ground surface we live on is behaving like a spring being squished. Sooner or later this stored energy will be released in the form of an earthquake.

P393 is one of a network of real-time GPS sites located in the western United States. While large earthquakes are unlikely to occur in eastern Oregon, it is important to compare data from P393 with data from more seismically active areas like P405 and NEAH. By having simultaneous access to data from sites throughout the Pacific Northwest, analysts can more reliably determine if there has been a large earthquake and where it occurred. In order to support real-time analyses, the GPS data from P393 are transmitted at a rate of 1 measurement per second and have less than 275 milliseconds latency. This means the GPS data go from satellites orbiting in outer-space through the antenna at the GPS site, across the radio links, into the internet and arrive at the analysis center in less than half a second!

Figure 1.Vectors of horizontal motions for sites in Oregon, Washington, and southern British Columbia, in a North American fixed reference frame.


Figure 2. Position changes for P393 (black) and P405 (blue) in a North American fixed reference frame. (For help interpreting the graphs, see the GPS Data page.)

Spotlight Questions

  • How fast is P393 moving, and in what direction?
  • Figure 1 shows horizontal vectors for each site. By looking at the data in Figure 2, do you think it makes sense to represent the motion in Oregon as a vector from a linear fit?
  • Classroom exercise: Detecting Cascadia’s changing shape with GPS Data

Last modified: 2019-12-26  16:24:52  America/Denver  


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