The EarthScope Facility’s three components include USArray, the Plate Boundary Observatory (PBO), and the San Andreas Fault Observatory at Depth (SAFOD). These components began operation in 2003, and have evolved into an integrated system of mature and robust observing systems, providing fundamentally important datasets that have thrust researchers into new realms of data analysis and discovery.
The USArray component of EarthScope is a continental-scale seismic and magnetotelluric observatory designed to provide a foundation for integrated studies of continental lithosphere and deep Earth structure over a wide range of scales. USArray is providing a new insight and new data to address fundamental questions in earthquake physics, volcanic processes, core-mantle interactions, active deformation and tectonics, continental structure and evolution, geodynamics, and crustal fluids (magmatic, hydrothermal, and meteoric). Over the wide frequency range of seismic waves transmitted through the Earth (hundreds of seconds to ten cycles per second), the sensors of the permanent and transportable seismic and magnetotelluric arrays will resolve the smallest background motions at the quietest of sites, while remaining “on scale” for all but the largest ground motions from regional earthquakes.
USArray comprises multiple observatory components: a Transportable Array, a gridded network of 400 seismometers, barometers and infrasound sensors rolling across the lower 48 United States and parts of southern Canada deployed for ~2 years per site, a Flexible Array, which includes more than 2,000 seismic systems available for PI-driven focused field experiments, and 20 magnetotelluric systems used for campaign deployments on discrete targets.
Data from these sites are collected on a regular schedule through recovery of data storage modules. The USArray project is guided by the USArray Advisory Committee.
For more information about the USArray observatory, visit the USArray website.
For more information about the current stage of USArray, click here.
For more information about data, click here.
The Plate Boundary Observatory (PBO) is the geodetic component of the EarthScope project, designed to study the 3D strain field across the active boundary zone between the Pacific and North American tectonic plates in the western United States. PBO is a network of more than 1,200 continuous GPS instruments, borehole strainmeters and seismometers, and tiltmeters installed primarily throughout the Western United States. The objective of PBO is to explore land motions related to movement of the Pacific, Juan de Fuca, and North American tectonic plates; such motions inform us about earthquakes, volcanoes, tsunamis, and other hazards related to plate tectonics. Data from PBO's integrated network of GPS stations, strainmeters and seismometers, coupled with aerial and satellite imagery, are providing important temporal constraints on plate boundary deformation and are improving our knowledge of the fundamental physics that govern deformation, faulting, and fluid transport in earth’s lithosphere. PBO is also used to remotely measure changes in water content of the troposphere, soil moisture content, snow depth, and ground motions related to changes in aquifers, droughts, and lake levels.
For more information, visit the PBO project page at UNAVCO.
Information about data here.
The San Andreas Fault Observatory at Depth (SAFOD) was a 3.1-kilometer deep borehole drilled directly into the San Andreas Fault midway between San Francisco and Los Angeles, near Parkfield, CA. Located in an area that has ruptured six times since 1857, the hole provided the first opportunity to observe directly the conditions under which earthquakes occur, to collect rocks and fluids from the fault zone for laboratory study, and to continuously monitor the physical condition within an active earthquake nucleation zone.
The cores can be interactively viewed in EarthScope SAFOD Core Viewer.
Information about data here.