The EarthScope Plate Boundary Observatory Unified Geodetic Network

EarthScope is a program funded by the NSF to explore the structure, evolution and geodynamics of the North American continent and to understand the processes that control earthquakes and volcanoes. By integrating scientific information derived from its multi-disciplinary observatories, EarthScope will yield a comprehensive, time-dependent picture of continent structure, kinematics and geodynamics beyond what any single discipline could achieve. The geodetic component of EarthScope is the Plate Boundary Observatory (PBO) who's instruments will characterize the secular deformation, episodic displacement and accompanying strain changes associated with plate boundary processes operating at periods of milliseconds to decades. PBO showcases the power of integrated geophysical observations in characterizing geophysical events and will add to our understanding of both the physics and the societal impacts of damaging earthquakes and volcanic eruptions.

The PBO is unprecedented in its number of sensors, the size of its geographic footprint, and the openness and availability of data and derived products. PBO's integrated network consists of arrays of GPS receivers, strainmeters, tiltmeters, InSAR an LiDAR imagery and geochronology, all of which will be used to deduce the North American strain field on timescales of seconds to decades.

The scientific payoffs from the EarthScope project are already being realized as the network nears completion. UNAVCO community scientific highlights based on PBO data include capture of the pre-eruptive, eruptive, and post-eruptive phases of activity at Alaska's Augustine Volcano during 2005 and 2006; dense coverage of the ongoing volcanic unrest at Mt. St. Helens; recording of large earthquakes near Cape Mendocino, in Parkfield, Russia, Tonga, and the Kuril Islands; and recording of four episodic tremor and slip events along the Cascadia subduction zone; integrated observations of accelerated inflation at Yellowstone; and unprecedented densification of constraints from the PBO Nucleus yielding first order constraints for continent- and plate-scale models of geodynamics.