The Plate Boundary Observatory’s geodetic observatory consists of a carefully designed and integrated network of over 1100 Global Positioning System (GPS) receivers, 75 borehole strainmeters (BSM), 79 borehole seismometers, 6 long-baseline laser strainmeters (LSM), 78 borehole seismometers, 100 meteorological sensors, and 26 tiltmeters. Taken together, these instruments record plate boundary deformation across a broad temporal and spatial spectrum. GPS is ideal for sensing Earth movements from days to decades, such as how large areas adjust following an earthquake, as well as permitting estimates of long-term and transient strain accumulation and tectonic plate motions.
Borehole strainmeters record deformation that takes place from seconds to months, consequently, they play a central role in observing phenomena that precede and accompany earthquakes and volcanic eruptions. Boreholes also provide low-noise environments for seismometers, permitting scientists to distinguish wind from seismic tremors in locations such as the Yellowstone caldera and the Pacific Northwest.
Laser strainmeters combine the high resolution of the borehole strain instruments with the long-term stability of GPS measurements, complementing information recorded by the borehole and GPS systems at many carefully chosen sites. Tiltmeters measure very small changes in the horizontal—whether land is tilting—and thus are used to detect volcano inflation and deflation associated with magmatic activity. Data from all of these instruments are freely available to scientific and educational communities, and to the public.