Earth Surface & Interior

The Earth’s surface and its interior are fundamental components of the Earth system influence and react to the dynamics of our oceans and atmosphere. Therefore, an understanding the dynamics of the solid Earth is essential to developing an interconnected view of Earth science and its applications that ranges from natural hazards and climate change to fundamental physics.

After excessive rainfall in the spring of 1995, the hillside above La Conchita, California collapsed, destroying 12 homes. Image courtesy of R.L. Schuster, U.S. Geological Survey.

As basic research leads to prediction of solid earth processes, so is the need to adapt this research to real societal problem solving. Knowledge that improves human abilities to prepare and respond to disasters involving the dynamism of the Earth’s interior has an immediate benefit to saving lives and property. Earth Surface and Interior focus area (ESI) seeks to coordinate the efforts of the NASA’s Research and Analysis Program in Solid Earth with the Applied Sciences Disaster Management Program to provide a continuum of development from research to applications that will enable first responders, planners, and policy makers to improve decision tools through NASA science and technology.

The strategic plan of the ESI focus area is entitled “Living on a Restless Planet” a.k.a. “The SESWG Report “identifies six scientific challenges and provides guidance for addressing these challenges. The six scientific challenges are:

1. What is the nature of deformation at plate boundaries and what are the implications for earthquake hazards?
2. How do tectonics and climate interact to shape the Earth’s surface and create natural hazards?
3. What are the interactions among ice masses, oceans, and the solid Earth and their implications for sea level change?
4. How do magmatic systems evolve and under what conditions do volcanoes erupt?
5. What are the dynamics of the mantle and crust and how does the Earth’s surface respond?
6. What are the dynamics of the Earth’s magnetic field and its interactions with the Earth system?

   The review of Living on a Restless Planet by the National Research Council for the National Academies is available. The findings and recommendations of the SESWG report have been refined and incorporated within the more recent report of the National Research Council entitled “Earth Science and Applications from Space: Urgent Needs and Opportunities to Serve the Nation”

   The six challenges call for a combination of satellite, airborne and ground based instruments for the most practical and cost-effective measurement over the required broad spatial and temporal scales. New remote sensing technologies are empowering scientists to measure and understand subtle changes in the Earth's surface and interior that reflect the response of the Earth to both the internal forces that that lead to volcanic eruptions, earthquakes, landslides and sea-level change and the climatic forces that sculpt the Earth's surface. For instance, InSAR and LiDAR measurements from satellite and airborne sensors are used to provide images of millimeter scale surface changes that indicate an awakening of volcanic activity long before seismic tremors are felt. Ground based geodetic GPS instruments provide time continuous measurements of this activity though they are often lost during intense volcanic activity. Thermal infrared remote sensing data from NASA satellites signal impending activity by measuring ground temperatures and variations in the composition of lava flows as well as the sulfur dioxide in volcanic plumes. The combination of instruments provide accurate information that can be used for both long term and short hazard assessment. These same LiDAR, InSAR and thermal instruments also provide accurate information on the velocity of ice steams, sub glacial lake activity, glacial rebound of the Earth’s crust, and the retreat and advance of mountain glaciers that are related to climatic changes.

   Lost Hills Subsidence: This brief clip depicts the subsidence of the Lost Hills Oil Fields near Bakers Field California as a result of oil withdrawal. This clip was produced by the comparison of a USGS Geological topographic data base from 1982 and the more recent Shuttle Radar Topography Mission. Approximately 9 feet of subsidence in recorded during this interval. Credit Ronald Blom and Vincent Realmuto, JPL.

   The numerous accomplishments of NASA’s ESI focus area include the mapping of the Earth’s Topography with theShuttle Topography Radar Mission (SRTM), the Gravity Recovery and Climate Experiment (GRACE) mission provides measurement of the Earth’s gravity with such accuracy that it provides monthly variations in the Greenland and Antarctic Ice Sheets, monthly estimates of water accumulation with the world’s river basins, while also providing measurements of crustal displacement in large earthquakes such as the Aceh earthquake of 2004. The Earth Surface and Interior Focus Area also supports NASA Space Geodesy Program and that provides the technology, infrastructure, measurements to maintain a global reference frame needed for a host of important activities from the maintenance of the GPS navigation system, the precision navigation of spacecraft and aircraft, the measurement of sea level change, and the remote sensing of the atmosphere and ionosphere needed for weather prediction.