Findings and Recommendations - Basic Research Opportunities in Earth Science - page 90

• Continental structure and evolution
• Geodynamics of the mantle and core
As currently conceived, EarthScope will comprise four programmatic
elements, each centered around a major new observational effort: (1) USArray,
for high-resolution seismological imaging of the structure of the continental crust
and upper mantle beneath the coterminous United States, Alaska, and adjacent
regions; (2) San Andreas Fault Observatory at Depth (SAFOD), for probing and
monitoring the San Andreas Fault at seismogenic depths; (3) Plate Boundary
Observatory (PBO), for measuring deformations of the western United States
using strainmeters and ultraprecise geodesy of the Global Positioning System;
and (4) Interferometric Synthetic Aperture Radar (InSAR) Initiative, for using
satellite-based InSAR to map surface deformations, especially the deformation
fields associated with active faults and volcanoes. Box 2.2 contains a more
complete description of these programs.
EarthScope will contribute substantially to understanding the structure,
evolution, and active deformation of the continents and the attendant earthquake
and volcanic hazards. It will also improve seismic images of the deep interior and
furnish important new data on basic geodynamic processes. The committee has
been impressed by the broad disciplinary representation and the diverse grass-
roots efforts that have contributed to the formulation of the EarthScope initiative;
these have included a series of open, well-attended workshops and a number of
symposia at national scientific meetings, as well as extensive discussions among
leaders in the relevant disciplines to translate the input material into a viable
science plan.
Finding: EarthScope will address major science problems related to the
continents and deep interior identified in this report. The scientific vision
and goals of EarthScope are well articulated and have been developed with a
high degree of community involvement. The committee strongly endorses
all four components of the EarthScope initiative.
To be successful, the major observational elements of EarthScope will have
to be backed by strong disciplinary programs to interpret the data within a larger
scientific context. Understanding the structure and evolution of the continents,
for example, will require a broad spectrum of geological, geochemical, and
geophysical studies, including targeted field work, to interpret the seismic
structure imaged by USArray. Such studies should not be confined just to the
United States, because many analogous and better-exposed structures in other
parts of the world may lead to a deeper and more general understanding. Offshore
investigations are required to study effectively even the North