Radar system maps movement along California faults
A new radar imaging system flying over California’s complicated network of faults on the belly of a Gulfstream jet is collecting some of the most detailed images yet of the Earth’s surface shifting and straining with seismic energy, scientists at NASA’s Jet Propulsion Laboratory say.
“This will show us where the faults are active,” Andrea Donnellan, a JPL geophysicist who is one of the project’s principal investigators, said Monday. “Where the ground is moving tells us what’s going on at depth.”
The data from this project could help scientists figure out where the risk of earthquake activity is highest, though the data will never be specific enough to predict a day, location or magnitude of a quake, she said.
“This will help us with the five- to 10-year time horizons,” Donnellan said. “We can see hot-spot maps and . . . figure out where to target our retrofitting.”
The device, called Uninhabited Aerial Vehicle Synthetic Aperture Radar even though it is currently mounted on a human-piloted plane, shoots long-wavelength radar beams at features on the ground and measures the reflections. Based at NASA’s Dryden Flight Research Center at Edwards Air Force Base, the plane flies about 45,000 feet above the ground along GPS-guided trajectories.
The project will map faults across about 70% of California, including a wide swath of Southern California, said the project’s chief scientist, Scott Hensley. The radar device is also used in other projects, such as studying glacier motion in Greenland.
The cost of developing the technology, modifying the plane and collecting data for the first year is about $30 million, Hensley said. The first images were collected in November, but scientists are still processing most of the data.
Satellites operated by other countries have collected radar data on surface deformation for years, but few use the long-wavelength radar that enables the NASA device to penetrate vegetation and focus more on the hard ground surface, said Paul R. Lundgren, another principal investigator on the project.
Planes’ proximity to the ground also improves the resolution by a factor of 10 over satellite images, he said.
Most earthquake scientists are excited about getting another tool, said David Sandwell, a geophysicist at UC San Diego who is not involved in the NASA project.
But, he added, “we don’t know what we’ll get out of it.”
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