Illustration by Brian Stauffer

Let us count the reasons to appreciate earthquakes.
Give up?

Not so fast. Earthquakes made the dramatic Sierra Madre Mountains. They gave us the Angeles National Forest, Mulholland crest and the Malibu hills. They gave us fine radio and television reception from the transmitters atop Mt. Wilson. Unlike the flat and earthquake-free Midwest, quakes gave us rugged natural features that protect us from floods and tornadoes, and that allow celebrities to indulge their eccentricities in cozy canyons.

Obviously, now that we have all these things, no one looks forward to more earthquakes. If it occurred at just the wrong place and time, a strong quake could kill thousands and devastate the region.

But living in fear of the Big One, which may or may not happen in our lifetime, precludes the nobler emotion of wonder at one of the great mysteries of science. Seismology is an open frontier so daunting as to force explorers to band into giant consortia, such as the world-renowned Southern California Earthquake Center (SCEC), a 62-university effort based at USC and responsible for major advances in the field.

Wonder leads to curiosity, and curiosity leads to knowledge. And perhaps, to know a thing is to fear it less.

Like doctors who smoke, seismologists affect nonchalance at the hazards they know so well, downplaying the 1994 Northridge quake – once the costliest natural disaster in U.S. history – as a relatively minor event.

A surprising 2007 SCEC-supported study by earth scientists James Dolan and Charles Sammis of the USC College of Letters, Arts and Sciences, published in the journal Geology and covered by news outlets worldwide, suggested reassuringly that Los Angeles is in an ongoing 1,000-year “lull” characterized by smaller and less frequent quakes. (Caveat: The study didn’t include the San Andreas fault. Caveat  No. 2: As any responsible homeowner would, Dolan has replaced the brick wall holding up his family’s house, a vintage Craftsman, with a proper concrete foundation bolted to the studs. Preparedness and nonchalance go hand in hand.)

Even between lulls, the typical fault is surprisingly considerate. Only 10 percent of the energy from an earthquake goes into ground waves. A long stretch of the San Andreas fault is known as the “creeping section,” because the rocks in that area are greasy enough to let the Pacific and Continental plates slide billions of tons past each other with only a little shaking. Even in the Los Angeles area, the two plates slip quietly at depths of 12 miles or more. It is only near the surface, where rocks cool and become rigid and get jammed, that the slow waltz becomes a breakdance.

Still, nature tries its best to avoid friction. Local seismologists take a special interest in the creek bed under the bridge outside Pasadena’s Jet Propulsion Laboratory. A sharp diagonal line runs up the steep hillside on the west side of the creek. That line is the boundary of the up-thrusting fault that made the Sierra Madre Mountains. The rock on the mountain side of the fault is granite – a hard and scratchy mineral hardly conducive to low-friction sliding.

Except that the slippery material near the fault line looks and feels nothing like granite. On a recent visit, Dolan scooped out a chunk with his bare hands, moistened it in the creek and shaped it into a little clay person.

“You shouldn’t be able to do that to granite,” he said with a nervous chuckle.

The pressure at the fault line had turned the granite, a high-end kitchen countertop material, into Play-Doh. This is the more compliant base the Sierra Madre Mountains will be sliding on, next time they move.

Other SCEC researchers, led by USC earth scientist Yehuda Ben-Zion, developed a theoretical model for ruptures along a fault that separates two different solids. The laws of physics dictate that when a fault moves, the heat from the scraping should liquefy the rock at the fault line. But the massive melt products predicted by this simple physics are not observed.

In a SCEC-funded study last year, Ben-Zion presented new evidence from local faults to support his theory: that the different rock compositions on either side of many big faults, like the San Andreas, make it easier for the fault to slide during an earthquake while preventing melting.

An unfortunate corollary of the theory is that a quake on the Mojave section of the San Andreas is likely to propagate mainly to the northwest – that is, toward Los Angeles.

“If you just happen to be in the way of the rupture, bad news for you,” Ben-Zion says. He estimates the waves would be three to five times stronger than previously believed.

The theory remains controversial, seismology being much like the thing it studies: First the ground shifts one way, then back the other way. But clearly, nature is doing something to make quakes a little less bumpy. Ben-Zion and others are trying to figure out what.

Jordan, a USC University Professor and the chief of SCEC since 2000, has left the most challenging goal of his career – earthquake prediction – for last. One of the most distinguished geophysicists of his generation, Jordan was already a full professor at Princeton by age 23 (despite having flunked out of Caltech in his junior year “because the ’60s were going on,” he later was readmitted). He made key contributions to understanding the inner structure of the Earth, showing how continents fit into tectonic-plate theory, and how convection currents in the mantle carry rock from tectonic plates that have “subducted,” or slipped under other plates, for more than 1,000 miles down into the Earth. His body of work earned him the 2005 Inge Lehmann Medal for deep-earth studies from the American Geophysical Union. Now he’s on a quest that has brought ridicule to many and success to none.

After all, it was less than four years ago that UCLA seismologist Vladimir Keilis-Borok, citing “a major breakthrough” by his research team, predicted a magnitude 6.4 quake within months in the Palm Springs area. Even though Keilis-Borok’s international team had successfully “predicted” two earthquakes in 2003, one in Japan and one in central California, it takes only one false warning to undermine a reputation.

Jordan has moved more cautiously into the prediction business. In 2005, he and former graduate students Jeffrey McGuire and Margaret Boettcher co-authored a study, published in Nature, that showed some earthquakes on the ocean floor can, statistically speaking, be predicted from smaller “foreshocks” to within an hour. Considering the gas company can give only a four-hour window for a service call, it was a stunning result. Unfortunately it was also limited, applicable only to a particular set of faults in the Pacific Ocean.

“This is the first demonstration of good short-term predictability for big earthquakes,” Jordan said at the time. “Some scientists believe that earthquakes come on suddenly with no warning signs, and the big ones are therefore unpredictable.

“In many parts of the world, they may be,” he said.

McGuire and Boettcher (now researchers at the Woods Hole Oceanographic Institution and U.S. Geological Survey, respectively), are investigating the fault system further, placing large numbers of sensors on the ocean floor in the hope of improving both accuracy and lead time. They and Jordan believe that foreshocks and main tremors share a common trigger – perhaps a slow, smooth sliding along the fault line. Such an event, called a “slow-slip transient,” also can occur before subduction quakes – in which one plate slides under another – like the one that set off the killer tsunamis of Dec. 26, 2004, in the Indian Ocean.

With the right type of sensors, Jordan says, “you might be able to see [the slow-slip transient] coming.”

Unfortunately for the prediction effort, the San Andreas fault is not in a subduction zone and does not appear to produce slow transients. But other research points to different clues, such as non-volcanic tremors detected both in subduction faults and, more recently, on the San Andreas fault at the site of the Parkfield quake of 1857, the most powerful in California history.

“So there is activity there, deep in the Earth’s crust, below where the earthquake occurs,” Jordan says. “That’s exactly the kind of signal that could be useful.”

Unpublished, ongoing research by Jordan and doctoral student Peter Powers shows an intriguing regularity in small earthquakes happening near Southern California fault lines. Jordan says: “We know that earthquakes trigger other earthquakes.  We want, for example, to be able to predict small earthquakes. We’ve got some really cool results on that.”

The latest part of this brick-by-brick effort is the Collaboratory for the Study of Earthquake Predictability (CSEP), a two-year-old initiative started by Jordan after seismologists from Japan, Europe, New Zealand and other countries gave the idea an enthusiastic reception.

“We get great gain by going worldwide,” Jordan says. “Because there are San Andreas-like systems in Turkey, and in Asia, and other places, so if we had many experiments going on at many places, we could start to build up the statistics on even big earthquakes much more rapidly.”

Even so, earthquake forecasters continue to suffer from invidious comparisons.

“I’ve heard scientists say we are 100 years behind the weather forecasters,” says Philip Maechling, director of information systems for the earth sciences department of the USC College, and technology architect for SCEC.

This is more self-deprecating than necessary, since the two groups work in vastly different time frames. Asking seismologists to predict an earthquake within months is like expecting meteorologists to nail the minute of the first patter of raindrops on the pavement from an incoming storm system.

Seismologists from SCEC, the U.S. Geological Survey and the California Geological Survey do have what they believe to be a pretty accurate long-range forecast. It finds a 97 percent chance of a large earthquake in Southern California within 30 years, with the San Andreas fault as the most likely source.

Keep in mind that while the San Andreas fault system is the most likely for a large quake, many more faults exist. In fact, there’s an 82 percent chance there will be a large quake on a fault other than the San Andreas.

“Large” in this case means at least magnitude 6.7 – about as powerful as the Northridge quake. (In seismology, decimals really matter.) The 30-year forecast for a quake of magnitude 7.5 or higher (more than 20 times as powerful as Northridge) is about one in three for Southern California.

Time to install those furniture straps you bought and threw in the closet. And to consider earthquake insurance. It was the California Earthquake Authority that requested the forecast – the first comprehensive, statewide assessment of earthquake probabilities – in order to set rates fairly and equitably.

No one can guarantee the accuracy of the model. But in contrast to making laws or sausages – activities not recommended for the squeamish, as the saying goes – the statewide forecast at least came from first-quality ingredients and practices, namely months of deliberations by the top experts in the field.

“That’s one of the great things we have at SCEC. You come to a meeting at SCEC where we’re doing these kinds of evaluations, you’ll see five members of the National Academy of Sciences,” Jordan says. “We really have the best earthquake scientists in the world involved in this stuff.”

Despite the dire overall predictions of the model, the news is not all bad. With probabilities dropping on some large faults, such as the San Jacinto fault through San Bernardino County, rates are likely to fall for some Californians.

More compelling news is coming out of a related SCEC project, a suite of giant computer simulations with names such as Cybershake and Terashake are attempting to describe the intensity of ground shaking at distant points from an earthquake. According to Jordan, the latest simulations show stronger-than-expected shaking in the Los Angeles area from an earthquake on the San Andreas.

Future, more detailed simulations are expected to influence local building codes by specifying vulnerabilities in specific areas and for particular types of structures, from highrises to apartment buildings to single-family homes.

These careful simulations eat up enormous chunks of computer time. SCEC is one of the largest recipients of supercomputing grants from the National Science Foundation, with $15 million of computer support in 2007 alone, along with $2 million of additional funding.

“With these computational resources, we will be able to simulate thousands of possible fault-rupture scenarios in Southern California, including the largest breaks on the San Andreas,” says Maechling, the IT architect.

On such a massive project, “we” includes not only SCEC, but also USC’s Center for High Performance Computing and Communications and scientists at the famous Information Sciences Institute of the USC Viterbi School of Engineering.

Other faculty at USC Viterbi also study earthquake behavior, but with a focus on structures. Civil and environmental engineer Yan Xiao researches seismic design and building retrofitting. His colleague Mihailo Trifunac studies ground motion and the interaction between soil and structure.

Another USC Viterbi scientist, Sami Masri, operates a massive “shake table” in the basement of Kaprielian Hall. On a recent visit, the table’s 40-foot square structure of steel beams on moveable bases was rigged with a mock hospital ceiling for a structural integrity test. (USC University Hospital, he notes, offering a bit of civil engineering trivia, was the country’s first hospital built on “passive base isolators” – rubber bushings that allow a building to sway mildly in response to ground shaking.)

Masri’s team also is working with Caltrans to monitor the Vincent Thomas Bridge, a crucial link on the Harbor Freeway between Los Angeles and its southern ports. In 2006, a boat failed to lower its boom as the tide came in and struck the bridge. Masri’s lab immediately received impact signals from 36 sensors on the bridge. They alerted the authorities. After a brief shutdown, the bridge was judged to be safe.

The same types of sensors could be used on downtown buildings to detect dangerous swaying, and just as importantly, to analyze ground motion after an earthquake, Masri says. But a combination of litigation anxiety and landlord reluctance has left the United States far behind Japan, China and other countries in highrise monitoring. The building code in Los Angeles currently requires just one sensor for tall buildings – hardly enough for proper assessment after a big earthquake.

“You can imagine that (after a big quake) engineers will be swamped with requests to quickly evaluate the condition of these structures,” Masri says.

When the Big One hits, what’s a terrified person to do, other than “drop, cover and hold on?” (Actually, there are plenty of other preparedness tips at www.earthquakecountry.info/roots/index.php, the online version of the popular SCEC booklet Putting Down Roots in Earthquake Country, though nothing per se on overcoming paralyzing hysteria.)

Knowledge of the thing can keep fear at bay. James Dolan, the SCEC researcher who prudently bolted down his vintage Craftsman, tells his undergraduate classes that earthquakes are a lot like thunderstorms. The fastest vibration, the so-called P-wave that jolts the house once and wakes you up, is like lightning. The slower S-wave, which causes the actual shaking, is like the thunder.

As with thunder and lightning, by measuring the time between the two waves, a trained observer can figure out the distance from the quake’s epicenter.

Dolan tells the story of the night the Northridge quake hit.

“I felt a P-wave hit,” he remembers. “I’m an earthquake nerd, I’m lying in bed, and I woke up and I said, ‘Big earthquake!’ And I started counting....”

(Notice that, ignoring expert advice in his enthusiasm, Dolan did not drop, cover or hold on.)

“...I was sitting in bed going: ‘A thousand ten, a thousand eleven... Finally I got to a thousand eighteen, and the shear waves hit.” He quickly calculated: “Eighteen seconds, 150 kilometers away ... bet you it’s the Santa Monica Mountains thrust fault!

“Obviously you’re concerned about people, but by the same token it’s an incredibly exciting phenomenon,” Dolan says. “When you realize exactly how much energy is being released, and what it means in terms of moving plates past each other...

“I find it absolutely fascinating. That’s why I work on earthquakes.”

Dolan tells all of his students: “The next time an earthquake hits, you guys are all going to be counting seconds, whether you think about it or not, and that’s going to take away some of the fear.”

Unless the quake is right under you, in which case you won’t be counting for long.

But as bad as it may feel at the time – and it could be bad if the San Andreas slips with a magnitude 7 temblor – Dolan and his colleagues take comfort in the knowledge that quakes in California do not compare to the truly monstrous subduction quakes. The one in Sumatra that started the killer tsunamis of 2004 was almost 1,000 times stronger than magnitude 7. In addition, modern building codes, redundant communication networks and strong community resources make California a pretty resilient place.

It is not so in other parts of the world.

Jean-Pierre Bardet, chair of USC Viterbi’s Sonny Astani Department of Civil and Environmental Engineering, has flown to many hard-hit regions as a pioneer in the field of post-earthquake reconnaissance – a field devoted to the collection and preservation of seismic data before clean-up and reconstruction crews obliterate traces of soil movement and building damage.

Bardet was recognized with the Lillian M. Gilbreth lectureship of the National Academy of Engineering for developing better methods to gather and save data. He introduced GPS tracking of all aircraft reconnaissance, and he made sure all observations were carefully indexed by time and geographic coordinates. In the early 1990s he was the first to distribute a post-earthquake reconnaissance report on the Internet, entering the data keystroke by keystroke with the now-ancient communication software Kermit.

Then there are the memories of the human consequences.

“We’ve been lucky in the United States. We didn’t lose that many people due to earthquakes,” Bardet says. (The death toll from the Northridge quake was 57.) “But imagine earthquakes killing thousands of people, back in Turkey (in 1999, in the city of Ismet). There is a smell associated with death. It’s really something shocking. And you know that (living) people are still there, under the debris, and that they are not going to be extracted right away, and there’s little chance they will survive.

“You know that death has struck there, where you’re walking. The human dimension is really overwhelming.

“It gives you a realization of the force of nature. I strongly urge (my students) to go there [on reconnaissance] and see for themselves,” he says.

Similar concerns animate Jordan, who as a member of the Council of the National Academy of Science pushed for the resumption of scientific exchanges between the United States and pariah countries, such as Iran. Last fall, Jordan joined an Academies delegation on a 10-day trip to the earthquake-prone nation. The visit produced several results, including a joint U.S.-Iran workshop on protecting brick structures from earthquakes.

“The problems that unite us are a lot bigger than the problems that divide us,” he said then. 

In other contexts, that might have had the ring of a platitude. But as shown by Jordan’s global earthquake prediction initiative, by the collaboration between U.S.-based engineers such as Bardet or Masri and their peers around the world, and by the 62 universities that make up SCEC, international teamwork in earthquake science is the smart way to solve an international problem.

It’s one more reason to appreciate earthquakes: not for what they do, but for what they bring out in us.

If you have questions or comments on this article, please send them to magazines@usc.edu.

For more information on earthquakes and the Southern California Earthquake Center visit: www.scec.org;   www.earthquakecountry.info/roots/index.php;   www.emi-megacities.org;   www.agu.org/inside/awards/bios/jordan_thomas.html.