Earthscope
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The EarthScope project is an undertaking funded by the National Science Foundation in partnership with the USGS and NASA to characterize the geology of North America. EarthScope is composed of three projects: USARRAY, the Plate Boundary Observatory PBO and the San Andreas Fault Observatory at Depth SAFOD.
The instrumentation of USARRAY consists of a series of portable and permanent seismometers that are being installed over a 10 year period beginning in 2004. The goal of USARRAY is primarily to gain a better understanding of the structure and evolution of the continental crust, lithosphere, and mantle underneath North America.
The Plate Boundary Observatory PBO consists of a series of geodetic instruments: Global Positioning System (GPS) receivers and borehole strainmeters that are being installed to help understand the boundary between the North American and Pacific plates. The backbone includes a network of more than 130 GPS receivers that will cover, when completed, the western continental US, including Alaska, at a receiver spacing of 200 km and the eastern US at a receiver spacing of 500 km. A series of focused dense clusters of 775 permanent GPS receivers and 175 strainmeters are being installed along fault zones and volcanoes in western North America and Alaska. These permanent networks are supplemented by a pool of portable GPS receivers that can be deployed for temporary networks, to measure the crustal motion at a specific target or in response to a geologic event. The Plate Boundary Observatory portion of EarthScope is operated by UNAVCO, Inc, a non-profit organization that supports research applications of high-precision geodesy.
The San Andreas Fault Observatory at Depth SAFOD consists of drilling a hole across the active San Andreas Fault at a depth of approximately 3 km. Samples collected during drilling, as well as data from instruments installed in the hole, will help to better understand the process that control the behavior of the San Andreas Fault.
