Global Positioning Instruments
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.
A backbone network of 116 new and 20 existing GPS receivers that will provide a long-wavelength, long-period synoptic view of the entire plate boundary zone including the eastern US.
To address a range of scientific issues including plate boundary dynamics, active tectonics, and seismic and magmatic processes, PBO will install a continuously recording GPS networks along the Pacific/North American plate boundary. This network will build upon, and augment existing geodetic networks such as the:
- › Southern California Integrated GPS Network (SCIGN)
- › Bay Area Regional Deformation Network (BARD)
- › Eastern Basin-Range and Yellowstone Spot (EBRY)
- › Northern Basin and Range Geodetic Network (NBAR)
- › Southern Basin and Range Geodetic Network (SBAR)
- › Pacific Northwest Geodetic Array (PANGA)
- › Alaska Deformation Array (AKDA)
Strainmeter strain rate sensitivity reaches a maximum at a period of a week and then decreases at longer periods due to an increase in the amplitude of the short baseline Earth noise spectrum. In real time, at long periods (months to a decade) GPS has greater sensitivity than strainmeters by one to two orders of magnitude. At intermediate periods (weeks to months) sensitivities are comparable, and at shorter periods (seconds to months) strain sensitivity is one to three orders of magnitude greater than GPS.