EarthScope, a major science initiative in the solid-earth sciences, has been described as “a new earth science initiative that will dramatically advance our physical understanding of the North American continent by exploring its three-dimensional structure through time.”1 EarthScope is an entirely new venture for the earth sciences, with an immense vision and scope. EarthScope proposes to cover the United States with a dense array of instruments designed to reveal how the continent was put together, how it is moving now, and what is beneath it. It is intended to provide an unprecedented, detailed image of the surface and what lies beneath it, and will undoubtedly change our view of the earth, much as the Hubble Telescope has changed our view of the universe. Only very recently has it become realistic even to think of implementing a project such as this, not just because the imaging technology is relatively new and needed to have its capabilities proven, but because only now are the information systems (and the experience with using them) in place to handle and distribute the vast amount of data that will be produced. Because the technical elements required for it to succeed have now been developed, and most importantly because of the enormous potential that new discoveries with direct societal benefit will result from analysis of these data, the committee concludes that this is an opportune time to undertake this project.
EarthScope is composed of three components for which funding from the Major Research Equipment program of the National Science Foundation (NSF) is sought, and a fourth component primarily associated with the National Aeronautics and Space Administration (NASA). The first three are the United States Seismic Array (USArray), the Plate Boundary Observatory (PBO), and the San Andreas Fault Observatory at Depth (SAFOD). The NASA component of EarthScope is the satellite-based Interferometric Synthetic Aperture Radar (InSAR).
Each component of EarthScope is designed to support and integrate with other components.
At the request of the National Science Foundation, the National Research Council (NRC) appointed a committee to review the science objectives and implementation planning of the three NSF components of the EarthScope initiative: USArray, SAFOD, and PBO. Although not formally asked to examine InSAR, the committee was requested to assess the overall EarthScope scientific objectives after considering the integrated nature of the entire initiative. The charge to the committee is presented in Box ES1.
At the request of the National Science Foundation, an ad hoc committee under the auspices of the Board on Earth Sciences and Resources will review the science objectives and implementation planning of three components of NSF’s EarthScope initiative: the United States Seismic Array (USArray); the San Andreas Fault Observatory at Depth (SAFOD); and the Plate Boundary Observatory (PBO). Although not formally reviewing the Interferometric Synthetic Aperture Radar (InSAR) element, the committee should assess the overall EarthScope scientific objectives after considering the integrated nature of the entire initiative.
In particular, the committee is asked to consider the following questions:
Following review of extensive written material and after hearing presentations by members of the EarthScope Working Group and other interested scientists, the committee was impressed with the integrated scientific objectives of the EarthScope project. Based on its review of the extensive scientific planning elements included within individual component white papers, it was clear to the committee that scientific planning is well advanced, and accordingly the committee believed that it could assess the project and make recommendations. The committee concludes that EarthScope is an extremely well articulated project that has resulted from consideration by many scientists over several years, in some cases up to a decade. During that time, the proponents have become experts, not just in the observing technology but in the data handling and retrieval systems that are necessary to manage information on this vast scale. The scientists involved could see the prospect of the EarthScope project, but waited until both the necessary expertise and reliable technology were available before proceeding.
The committee concludes that EarthScope will have a substantial impact on earth science in America and worldwide. It will provide scientists with vast amounts of data that will be used for decades. The intention of EarthScope to make all its data freely available on the Internet, in as near real-time as possible, is both admirable and open-spirited. It will encourage research and educational collaboration throughout the world, ensuring that the maximum possible benefit and insight are extracted from the data collected. The scientists involved with EarthScope recognize that the free and open use of the data ensures rigorous quality assessment. In addition, they have measured the success of existing and past global monitoring programs in part by the number of people who use the data. EarthScope has the potential of providing scientific and technological leadership to the world’s seismological community. This integrated system for looking into the subsurface realm of a significant part of the North American continent could be used as a model for the other continents—Africa, Asia, Europe, Australia, South America, and Antarctica.
The committee makes a series of recommendations encompassing science questions, management, education and outreach, and partnerships.
SCIENTIFIC RATIONALE AND SCIENCE QUESTIONS
The committee concludes that the time is right to undertake a full exploration of the nature of the continental crust of the United States and its underlying mantle. Such exploration is a critical requirement for understanding the nature of the earth on which we live and how society needs to manage and adapt to its rhythms and processes.
The committee strongly endorses the integrated approach to the investigation of the lithosphere and mantle underlying the United States proposed in the EarthScope initiative, including its four components: USArray, PBO, SAFOD, and InSAR. The committee concludes that the scientific rationale for EarthScope is sound, that the scientific questions to be addressed are of significant importance, and that no necessary components have been omitted. The committee recommends that that all four EarthScope components be implemented as rapidly as possible.
Answering the key questions posed for the EarthScope science initiative will require the participation of scientists from across all the disciplinary programs of the Geosciences Directorate of NSF, particularly the Division of Earth Sciences (EAR).
The NSF should ensure that EarthScope’s scientific potential is effectively realized and capitalized upon by continuing its support for the disciplinary and interdisciplinary programs within NSF’s Division of Earth Sciences (EAR) that form the scientific foundation of the project.
In recent years, InSAR has made spectacular contributions to imaging parts of the earthquake cycle and revealing the motion of magma at depth beneath volcanoes. The committee believes that InSAR too must be perceived as an integral part of EarthScope.
The committee concludes that InSAR is an integral part of the EarthScope vision that will greatly enhance the effectiveness of the project, and it should not be viewed merely as a desirable add-on to the project. The committee urges NSF and NASA to collaborate to realize this goal at the earliest opportunity, so as to make InSAR capability a reality during the lifetime of the other EarthScope components.
IMPLEMENTATION AND MANAGEMENT
The effective functioning of the EarthScope management structure, to achieve the required integration of the different components, will depend on details that are yet to be developed.2 EarthScope will need a mechanism to ensure integration, coordination, and synthesis of the interdisciplinary studies carried out by individual investigators and small groups of investigators.
The committee recommends that EarthScope look beyond the development of the facility to the operational phase of the scientific program, and develop a strategic science plan to accomplish its long-term scientific goals. Such a plan should include a scientific advisory structure encompassing all elements of EarthScope and all appropriate branches of the earth sciences to provide oversight and advice on the scientific directions of the program, and to coordinate its scientific activities. It should also incorporate a mechanism for providing advice to NSF regarding EarthScope programmatic funding priorities. The advisory structure should also include liaisons to other programs that are either complementary or will help fulfill the broader EarthScope vision of understanding the structure and evolution of the North American continent.
EarthScope will result in observations that are certain to reveal new and unexpected events and targets.
The committee urges EarthScope management to establish a mechanism to rapidly and effectively direct appropriate equipment and expertise towards any unexpected phenomena that may be revealed during its implementation.
EDUCATION, OUTREACH, AND COMMUNICATION
EarthScope provides an excellent opportunity to excite and involve the general public, as well as K-12 and college students, to work together with the earth science community to understand the earth on which they live.
Because EarthScope provides a unique opportunity that must not be missed, the committee recommends that the education and outreach aspects of EarthScope, as currently incorporated in EarthScope planning documents, should be strongly and realistically supported. They must be an integral component of the project. Education specialists should be involved in both the development and execution of the education and outreach programs.
The earth sciences have the task not only of understanding how our planet works, but also of dealing with the societal and economic impacts of the earth’s processes and their effects on human life on the earth’s surface.
As they continue to develop documents to inform the public about the project, the committee recommends that the EarthScope proponents forcefully communicate the role of EarthScope as an important source of the earth science information required by
society for natural hazard mitigation, resource utilization, land-use planning, and environmental protection.
Understanding the dynamics of plate movements and plate boundaries requires knowledge about motions offshore, because although the continental crust extends far beyond the present shoreline, the EarthScope USArray and PBO installations do not extend into the marine realm. A complementary program, NEPTUNE, plans to make similar measurements off the coast of the Pacific Northwest, and other members of the ocean science community are planning to deploy ocean bottom seismometers (OBS) at a range of locations off the coasts of North America.
The committee recommends that the EarthScope Working Group actively pursue coordination between the EarthScope and ocean geoscience programs, including NEPTUNE, to ensure that the establishment of EarthScope facilities and the deployment of GPS-acoustic, strainmeter, and OBS arrays supported by the marine geological and geophysical community are complementary.
Several large scientific programs are currently in the process of planning extensive educational efforts. An example of particular scientific significance to EarthScope is the proposed NEPTUNE program.
The committee recommends that EarthScope establish liaisons and communications with other appropriate programs to build on existing progress in the development of major geoscience educational and outreach efforts.
The EarthScope Working Group has categorized the EarthScope initiative as seeking to “…dramatically advance our physical understanding of the North American continent by exploring its three-dimensional structure…” and has indicated that it will seek to collaborate with colleagues in Canada and Mexico to integrate data produced by programs in these countries with EarthScope data from the United States. The committee considers that international collaborative programs will significantly enhance the value of the information amassed by research in the United States.
The committee endorses the intent of the EarthScope proponents to seek collaborations with colleagues in Canada and Mexico to extend the understanding of crustal and lithosphere dynamics beyond the political borders of the United States. The committee believes that EarthScope will provide a powerful stimulus for joint international scientific programs, in the same way as the transects compiled during the Decade of North American Geology (DNAG) and the creation of continent-wide data sets for potential fields (e.g., gravity and aeromagnetics) stimulated past collaborations.
The committee concludes that the plan for the integrated EarthScope facilities is sound. The plan reflects the input of a very broad cross-section of the geophysical community and mature consideration and planning over a decade. The project is very well conceived. The committee is confident that through broad earth science community involvement, the detailed science plans and strategies for the use of the facilities will be similarly well conceived and articulated. The potential scientific benefits of the total program to the earth sciences are of immense importance; the potential benefits to society of “applied science” stemming from the program are equally outstanding. EarthScope represents a truly visionary program for the earth sciences. The committee enthusiastically endorses the total program and all of its components.