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Tom Jordan takes on quake prediction

AAAS Fellow Tom Jordan stands outside the Zumberge Hall of Science at the University of Southern California, home of the Southern California Earthquake Center. (Photo: Rebecca Fairley Raney)

In California, everyone has heard about the "Big One," that long-predicted temblor that could bring the state to a standstill. Spend a few minutes talking with AAAS Fellow Tom Jordan, however, and it's clear that the concern isn't so much about what the first big quake knocks loose, but what the second and third will bring down.

"We're going to get hammered,"  says Jordan, "and I think people are going to be amazed at what an earthquake is going to do."

Jordan is university professor and W.M. Keck Professor of Earth Sciences at the University of Southern California (USC), as well as director of the Southern California Earthquake Center, where he conducts and oversees research that anticipates a series of large earthquakes along a fault, an event that could be called the "Big Series," or "Seismic Sequence."

The center is a collaboration among seismologists from all over the world. Much of the research involves running so many variables to simulate earthquakes that the group is now one of the largest users of supercomputing time in the world.

Jordan works from a spacious office in USC's Zumberge Hall of Science, the kind of beautiful red-brick building, built in 1929, that's the last place you'd want to be during an earthquake. Although it has been retrofitted, Jordan concedes there is an irony in its role as headquarters for the Southern California Earthquake Center.

Since the 1960s, Jordan has been drawn to the culture and the landscape of California. But he has found, over the decades, that living here has both inspired and dulled him.

Jordan entered the California Institute of Technology after graduating from a government school in the canal zone of Panama, where his father was stationed with the Army. Jordan said he was ill-prepared for Caltech. He nearly flunked out as a junior -- but the poor preparation was only part of the reason.

"It was the mid '60s," he explains, \and I fully participated in it."

As a student, he had a job that involved placing seismometers in the Sierra Nevada. He loved the idea that he could do physics in the outdoors. And despite Jordan's class standing, Don Anderson, the head of the seismological lab at Caltech, invited him to continue doing research and complete his studies.

In the years that followed, Jordan took up work at the Scripps Institution of Oceanography near San Diego. But after seven years, he thought he was getting "a little soft in the head" on the beach at Scripps, so he moved on to the Massachusetts Institute of Technology, where he eventually became head of the Earth, Atmospheric and Planetary Sciences Department. 

During his time at Scripps and at MIT, his research involved refining theories about plate tectonics. His work showed that lithospheric plates go deep into the Earth, and that the mantle reaches a depth of 400 km (249 miles) -- much deeper than anyone initially thought.

"It meant that the whole mantle was convecting," Jordan says.

After a decade of administration at MIT, Jordan wanted to get back to research and cast his lot with the Southern California Earthquake Center. What drew him was the ability to apply a systems science approach to earthquake problems. It involves applying physics-based modeling to earthquake problems, allowing geophysicists to raise questions that they never could have considered before.

For one project, called CyberShake 3.0, a team is using "full 3D wave propagation simulations to forecast ground motions that will be produced by specific ruptures," according to the project's website.

The researchers are producing the next version of the California seismic hazard map — the map upon which premiums for earthquake insurance are calculated. This time, however, the report will anticipate "physics-based hazard results" based upon simulated ruptures.

The methods are controversial.

"Some seismologists have been arguing that the uncertainties overwhelm us, and we ought to stop trying," Jordan says. "But that's not a very scientific attitude, in my view."

The models take into account the ruptures of faults; the directivity, or the way a pulse would shoot down a fault and cause shaking; and sedimentary basins, which account for the soft spots where shaking would be the worst.

Other research projects also have changed scientists' thinking about the relationships among faults and events. Twenty years ago, seismologists told reporters that earthquakes were isolated events. Now there's no question, Jordan says, that one quake can lead to another.

The modeling has cranked up warnings for the San Andreas fault, an 800-mile-long line that slashes across the California coast from nearly top to bottom. Two large plates -- the North American and the Pacific -- collide at the fault. The southern portion of the fault runs from Parkfield in Monterey County to the Salton Sea and has a 59 percent chance of producing a >6.7 magnitude quake in the next 30 years, according the Uniform California Rupture Forecast, which is part of Jordan's research group at the Southern California Earthquake Center. This portion has been quiet for 150 years.

Jordan doesn't hesitate to describe the danger, and he delivers his prediction:

"Earthquakes don't occur randomly in time. The San Andreas system is locked, loaded and ready to roll."

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AAAS Fellow Tom Jordan stands outside the Zumberge Hall of Science at the University of Southern California, home of the Southern California Earthquake Center. (Photo: Rebecca Fairley Raney)
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