Science Opportunities - Basic Research Opportunities in Earth Science - page 61

BOX 2.2. EARTHSCOPE INITIATIVE

EarthScope is an NSF initiative to build a network of multipurpose
instruments and observatories that will significantly expand capabilities to
observe the structure and active tectonics of the North American continent.
The initiative will deploy four new observational facilities:
1.

USArray will dramatically improve the resolution of seismic images of
the continental lithosphere and deeper mantle below the United
States and adjacent regions. USArray will have three components:
(1) a transportable telemetered array of 400 broadband seismometers
designed to provide real-time data from a regular grid; (2) a flexible
array of `2400 portable seismometers (using natural and explosive
sources) for high-density, shorter-term observations of key targets
within the footprint of the larger transportable array; and (3) a fixed
network of seismometers to provide continuous long-term
observations and augment the U.S. Geological Survey (USGS)
National Seismic Network.

2.

San Andreas Fault Observatory at Depth (SAFOD) will directly
sample fault zone materials (rock and fluids), measure a wide variety
of fault zone properties, and monitor a creeping and seismically active
fault at depth. A 4-km-deep hole will be drilled through the San
Andreas Fault zone close to the hypocenter of the 1966 Parkfield
earthquake. Fault zone rock and fluid will be retrieved for laboratory
analysis, and geophysical parameters, including seismicity, pore
pressure, temperature, and strain, will be measured and monitored
downhole and in adjacent areas. Instruments will be emplaced for
long-term (20-year) observations of fluid activity, seismicity, and
deformation.

3.

Plate Boundary Observatory (PBO) will permit study of the three-
dimensional strain field resulting from deformation along the Pacific-
North American plate boundary. PBO will comprise (1) a backbone
network of continuously recording, telemetered GPS receivers with
100 to 200-km spacing to provide a long-wavelength, long-period
synoptic view of the entire plate boundary zone, from Alaska to
Mexico, and (2) clusters of strainmeters and GPS receivers in
technically active areas such as major faults and magmatic systems.

4.

Interferometric Synthetic Aperture Radar (InSAR) will provide
spatially continuous, intermittent strain measurements over wide
geographic areas via a dedicated satellite mission to be carried out
jointly between the National Aeronautics and Space Administration
(NASA), NSF, and USGS. InSAR images will complement the
continuous GPS point measurements of PBO. The ideal mission will
provide dense spatial (100 m) and temporal (every eight days)
coverage with vector solutions accurate to 1 mm over all terrain
types.

SOURCE: http://www.earthscope.org .