Plate Boundary Observatory

Plate Boundary Observatory. The Plate Boundary Observatory is a geodetic network designed to measure the strain across the active boundary between the Pacific Plate and the North American Plate. It constitutes the geodetic component of the larger EarthScope project, funded by the National Science Foundation and operated by the U.S. Geological Survey. This permanent array of high-precision instruments provides continuous data critical for understanding plate tectonics, earthquake processes, and volcanic activity across the western United States.

Overview

The observatory is a continent-scale network of over 1,100 permanent stations stretching from Alaska to Mexico, and from the Pacific Ocean to the Rocky Mountains. It is a cornerstone of the EarthScope initiative, which also includes the USArray seismic network and the San Andreas Fault Observatory at Depth. By continuously monitoring the deformation of the Earth's crust, it provides an unprecedented view of the complex interactions along the Pacific Ring of Fire. This data is essential for researchers at institutions like the University of California, Berkeley and the University of Washington.

Design and instrumentation

The network integrates three primary geodetic technologies to measure crustal motion with millimeter-level precision. A backbone of over 1,100 continuous Global Positioning System receivers tracks three-dimensional positional changes. Complementing these are 75 strainmeter installations, primarily laser strainmeters and borehole strainmeters, which detect subtle crustal stretching and compression. Additionally, a network of 28 long-baseline tiltmeters measures very small changes in ground slope, providing high-frequency data near volcanic and seismic zones. This multi-instrument approach, managed by facilities like the UNAVCO consortium, ensures robust and complementary measurements of tectonic deformation.

Scientific objectives and applications

The primary scientific goal is to quantify the strain accumulation and release processes associated with major geologic hazards. Data is used to develop and refine models of earthquake cycles on faults like the San Andreas Fault and the Cascadia subduction zone. It also monitors magma movement and ground deformation at volcanoes within the Cascade Range and Alaska Peninsula. Research applications extend to studying post-glacial rebound, the dynamics of slow slip events, and the distribution of strain across broad plate boundary zones. Findings are regularly published in journals such as *Science* and the Journal of Geophysical Research.

Data access and products

All data is freely and openly available in near-real-time through the UNAVCO Data Archive and the NASA JPL analysis centers. Standard data products include time series of daily GPS positions, strain and tilt records, and derived velocity fields for the western United States. These datasets are fundamental for numerous research projects and are incorporated into hazard assessments by the U.S. Geological Survey and state agencies like the California Geological Survey. The data infrastructure supports the broader goals of the National Earthquake Hazards Reduction Program.

History and development

The concept originated from scientific planning in the 1990s, culminating in its formal establishment as a major component of the EarthScope project, which was funded by the National Science Foundation in 2003. Construction and installation of the vast network occurred primarily between 2004 and 2008, involving collaboration between UNAVCO, the U.S. Geological Survey, and numerous universities. It achieved its initial operational capability in 2004 and full completion in 2008. Since then, it has become an indispensable tool for the national and international geoscience community, providing a long-term record essential for distinguishing between episodic events and secular tectonic motions.

Category:Geophysical observatories Category:Plate tectonics Category:Earthquakes