Plate Boundary Observatory

The Plate Boundary Observatory (PBO) is a research project that studies the motion of the Pacific and North American tectonic plates, and measures the resulting earth deformation that causes earthquakes and volcanic activity.

Geodetic imaging data is transmitted, often in realtime, from a wide network of GPS stations, augmented by seismometers, strainmeters and tiltmeters, complemented by InSAR (interferometric synthetic aperture radar), LiDAR (light detection and ranging) imagery, and geochronology. High-precision instrumentation enables units to detect motions down to sub-centimeter level.

Instrument installation and data processing are conducted by the GAGE (Geodesy Advancing Geosciences and EarthScope) Facility of UNAVCO, a non-profit university-governed consortium that facilitates geoscience research and education using Geodesy.

The GPS stations are categorized into clusters. The transform cluster is near the San Andreas Fault in California; the subduction cluster is in the Cascadia subduction zone (northern California, Oregon, Washington, and southern British Columbia); the extension cluster is in the Basin and Range region; the volcanic cluster is in the Yellowstone caldera, the Long Valley caldera, and the Cascade volcanoes; the backbone cluster is at 100–200 km intervals across the United States to provide complete spatial coverage.

PBO is part of the Earthscope Project, an earth science program using geological and geophysical techniques to explore the structure of the North American continent and to understand the origin of earthquakes and volcanoes. Earthscope is funded by the National Science Foundation in conjunction with the USGS and NASA.

An EarthScope GPS sensor, a component of the Plate Boundary Observatory (PBO) system.

Some scientific questions that are being addressed by the EarthScope project and the PBO include:

• How does accumulated strain lead to earthquakes?
• Are there recognizable precursors to earthquakes?
• How does the evolution of the continent influence the motions that are happening today?
• What happens to geologic structures at depth?
• What influences the location of features such as faults and mountain ranges?
• Is it inherited from earlier tectonic events or related to deeper processes in the mantle?
• How is magma generated? How does it travel from the mantle to reach the surface?
• What are the precursors to a volcanic eruption?