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The goal of the surface deformation observational strategy is to
measure spatially continuous displacements of the Earth's
surface on both temporally and globally comprehensive bases. Repeat
observations must resolve rapid deformational processes such as
earthquakes, volcanic eruptions, glacial flow, and regions of devastated
infrastructure due to fires and earthquakes in urban areas. The
ability to map quickly these regions of devastation will substantially
improve capabilities for rapid emergency response to these destructive
forces. It is important as well to measure slow deformational processes
such as interseismic strain accumulation, magma chamber pressurization,
surface displacements from migration of crustal fluids (e.g., water
and oil), and motions of the ice sheets.
Modeling
to date indicates that accuracies of 1 mm/yr over 50-km horizontal
scales are needed. Such a capability will permit an assessment of
how slow transient events (e.g., modest strains over large areas)
relate to earthquakes, distinguishing between strain accumulation
on a single fault from strain on multiple faults, and accurate determination
of the nucleation of earthquakes and the effects of fault asperities
on earthquake slip.
Suggested
mission phasing and requirements
Immediate
(1–5 years): A single dedicated InSAR satellite
operating at L-band, with left/right-looking capability and weekly
access to anywhere on the globe. Such a mission should include precise
orbit determination and ionospheric correction capabilities. This
mission should achieve accuracies of 1 mm/yr surface displacement
over 50 km horizontal extents in selected areas. Displacement maps
should cover 100-km-wide swaths.
Near Term (5–10 years):
A constellation of InSAR satellites capable of producing deformation
maps at nearly daily intervals. Maps should extend several hundred
kilometers in swath width and provide full vector surface displacements
at accuracies of submillimeter per year over 100-km spatial extents
and 1-m spatial resolution.
Long term (10–25 years):
Hourly global access from a constellation of InSAR satellites in
low Earth or geosynchronous orbits. There should be an increase
in the density of continuous ground and seafloor geodetic observations.
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