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Flying radar system to help track California's earthquake faults

June 23, 2009 |  7:20 am

Quakedata

A new radar imaging system on the belly of a Gulfstream jet that is flying over California’s complicated network of faults has started 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 said.

“This will show us where the faults are active,” said Andrea Donnellan, a JPL geophysicist who is one of the project’s principal investigators. “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 so specific as to predict a day, location and 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, the Uninhabited Aerial Vehicle Synthetic Aperture Radar (even though it is currently being used on a human-piloted plane), mounted on the 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.

It also will fly for other projects, such as studying glacier motion in Greenland. Developing the technology, modifying the plane and collecting data for the first year will cost about $30 million, he said. The first images were collected in December, but have not yet been fully processed.

Satellites operated by other countries have collected radar data on surface deformation for years, but most don’t 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.

 A plane is also able to fly much closer to the ground than a satellite orbiting in space, improving the resolution by a factor of 10, 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.”

-- Jia-Rui Chong

Image: Screen grab from a flyover of the San Andreas fault in the San Francisco Bay area. Credit: NASA JPL

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