Earthquake
science is poised to capitalize on a revolutionary capability
for observing global crustal deformation. The concurrent improvements
in seismic monitoring networks, high-performance computing,
and geodetic measurement of crustal deformation have yielded
significant advances in knowledge of fault behavior and crustal
stress during the past decades.
A
major leap forward will be enabled with the ability to monitor
crustal deformation with high temporal and spatial resolution.
That capability will extend the observational spectrum into
the realm of transient and aseismic deformation. These fast
but seismically quiet deformation processes, which are at
present poorly understood components of the strain budget,
are key to developing a complete understanding of earthquake
physics. Community models of earthquake physics and seismic
hazards, developed in a data-rich environment will rapidly
evolve in response to the data. These new models are expected
to yield future earthquake forecasts of useful dimensions
that will feed decision support tools to mitigate losses from
future large earthquakes.
The
Global Earthquake Satellite System (GESS) study responds to
the clearly articulated need within the solid-Earth science
community for dense surface deformation data. It is a detailed
implementation plan in alignment with the recommendations
of the Solid Earth Science Working Group (SESWG), and charts
the course for NASA to make major contributions to the interagency
EarthScope program, while broadening those goals to a global
scope. In the GESS study, we explored the requirements space
for various components of an integrated system, but focused
our mission architecture studies on systems that deliver high-accuracy,
high-resolution surface deformation using InSAR. Detailed
science requirements were gathered from the wider community
to guide the studies.
The
major conclusion of the architecture studies is that a constellation
of InSAR satellites is needed to address the requirements
for monitoring a spectrum of steady and transient deformation
processes. To ensure the ability to access any area on the
surface of the Earth within 24 hours would require two LEO
satellites in orbits above 1000 km. A few MEO or GEO satellites
would be equivalent to many spacecraft in LEO and would fully
characterize the known transient processes such as postseismic
relaxation, slow earthquakes, creep events, and accelerated
slip, with full global coverage. |