Ran across something called “Earth Scope” on a recent visit to the Mt. Lassen Volcanic National Park. Some quick googling yielded:
GPS geodesy provide complementary measurement systems for resolving strain-rate over the time period proposed for the Plate Boundary Observatory. GPS strain rate sensitivity is better at longer periods, which allows for the detection of plate motion and long-period transients.
This location is part of a backbone network of 136 sites that provide a long-wavelength, long-period synoptic view of the entire plate boundary zone.