NASA uses radar imaging to study quake fault

February 12, 2010 7:14:48 PM PST
At the corner of Euclid and Keith avenues in the Berkeley Hills, residents have grown accustomed to the sound of work crews ripping up their street.

"They dig it up almost every winter for something," said Linda Kanat. She bought her home some 35 years ago, and vaguely remembers a warning about the Hayward Earthquake Fault, which runs directly through the street and triggers landslides that continually change the local terrain.

"There are problems with the water lines, the sewer lines, all of that," she said.

But those would be minor inconveniences compared with the projected 6.8 big one that is now overdue.

"The Hayward Fault is ready," said Dr. Roland Burgmann of UC Berkeley, a geophysicist who wants to remind us that the East Bay, and all of this region, are on borrowed time. The Hayward Fault tends to seriously rupture every 140 years. You might want to do the math.

"The last quake was 1868," said Burgmann. "It's now 140 years later, plus two."

For that reason, Burgmann has more than a passing interest in a modified Gulfsteam G3 flying out of NASA's Dreyden Research Center. The pod beneath it contains an extremely sensitive radar. NASA has used it to study glaciers, rainforests, volcanoes, and now, the Hayward Fault.

We followed along, recently, as the plane used an ultra sensitive GPS system to traced a 2,000-mile grid pattern across the San Francisco Bay Area. The route is so precise that it varies less than 10 meters from one trip to another.

"We can do it 10 minutes later, two months later, two years later. It depends how fast things are changing," said Dr. Thomas Mace, who runs the flight testing program at Dreyden. "We're able to measure changes of a centimeter. That's much less than an inch, and from 41,000 feet."

They transfer that raw data to the Jet Propulsion Laboratory in Pasadena. There, another geophysicist, Dr. Eric Fielding, can lay one set of images on another to track shifts along the fault line.

It can even detect the changes in Linda Kanat's backyard. Landslide areas appear as yellow blotches on topographic maps.

"The thing we look at on the Hayward Fault is that some parts are sliding all the time," explained Fielding. "They are the ones not likely to break. The other parts are locked and building up stress. That is where the fault will rupture at some time in the future."

One of those areas would be Memorial Stadium on the UC Berkeley campus. "It's right on the fault line," said Burgmann, as we traced that fault through the length of the field. Because of the danger, the university has begun a $300 million renovation.

And, it explains all those unnerving cracks you will see if you look closely at the stadium's interior structure. Geophysicists call it "fault creep" from the Earth's forces sheering it apart. Some of the cracks are so large that a person can stick most of his hand in them, which is hardly reassuring for season ticket holders.

For the record, the California student section, on the east side, is safer than the west, which was built on fill. "And, I think they put the Stanford fans in the most dangerous seats of all, up there," joked Burgmann, who happened to receive his Ph.D. from that fine institution.

The holy grail in earthquake studies would be to reach a point where we might accurately forecast them. Science remains a long way from that, but it's closer than ever before, even if the most detailed view comes at 600 miles an hour, from 41,000 feet.