October 22, 2005

Despite decades of intense research, predicting when earthquakes are likely to strike is a lost cause, according to a report published last week by some of the world’s top earthquake scientists.

The gloomy conclusion dashes hopes that early warning systems could be developed. Instead, the team urges countries in high-risk regions to develop and enforce strict building codes to ensure homes, hospitals and fire stations are more resilient to earthquakes.

The research team, made up of seismologists from the US Geological Survey in California and a number of universities, set out to predict when an earthquake would occur near the ranch town of Parkfield on the San Andreas fault in California. Records show that at least six powerful earthquakes have struck since 1857, making it one of the most earthquake-prone sites in the world.

In anticipation of another earthquake at Parkfield, the scientists fitted the faultline with a network of sensors capable of detecting tiny movements of rock. “We knew it was going to happen and we knew how big it would be, we just didn’t know when,” said Robert Nadeau of the University of California, Berkeley.

But when the earthquake struck last year, there was no warning. “Even with such a well monitored area, we weren’t able to tell that it was coming. There was nothing that might have been useful in predicting it,” said Dr Nadeau, whose study appeared in the journal Nature.

The failure of such a hi-tech effort to unravel any signals that could foretell the imminent quake suggests prediction of any earthquake is likely to be a pipe dream. “I don’t know if it’ll ever be possible with today’s technology,” said Dr Nadeau. While prediction is still a worthwhile research goal, the scientists urged countries at risk of earthquakes to instead invest in ways of mitigating the damage caused by shockwaves.

“It’s not earthquakes that kill people, it’s the way houses are built and whether they are built to withstand earthquakes, which is what we’ve seen in Pakistan,” said Felix Waldhauser, a co-author on the paper at Columbia University, New York.

Earthquakes destroy houses by shaking the ground from side to side. If buildings are made of brittle materials such as bricks, they can break apart.

In previous earthquakes, homes not bolted to foundations have slipped off and cracked in half. In San Francisco and earthquake-prone Japan, buildings have been designed to be more flexible so they sway as the ground shakes. Reinforcing beams have been added to older buildings to strengthen them against sideways jarring.

However, for poorer countries, the options are more limited, said Ian Main, a seismologist at Edinburgh University. “It’s a real problem as to what poorer countries are supposed to do,” he said.

Emergency preparedness

Mother Nature has provided emergency responders, scientists, engineers and transportation and utility operators with much to discuss lately. At the semi-annual meeting of the Earthquake Research Affiliates held at Caltech recently, speakers addressed not only the recent return of magnitude-5.0 temblors to California, but also major quakes in Pakistan and off the coast of Sumatra, besides the affects of Hurricane Katrina on buildings along the Gulf Coast.

The overriding message was the importance of focussing on emergency preparedness. Lucy Jones, the US Geological Survey’s scientist-in-charge for Southern California, started the meeting by rattling off a list of the area’s three earthquakes greater than magnitude 5.0 and four others above magnitude 4.5 that have hit since April. “We finally started having some fives again in Southern California,” she said.

Three of those quakes occurred in a swarm between Aug 28 and Sept 1 in an area that seismologists call the Brawley Seismic Zone near the Salton Sea — an area once considered a hotbed for earthquakes, but which has been relatively quiet for the past 20 years.

“There was a time when the Imperial County was by far the seismically most active part of California, in the ‘70s, and it’s possible that we could be headed back to that,” she said. Jones then switched topics to compare the Los Angeles Basin and the fault system which runs along the front of the San Gabriel Mountains, with the area that has been devastated by the magnitude-7.6 earthquake, which struck along the western edge of the Himalayan mountain front on Oct 8.

Because a piece of California is tectonically having difficulty pushing around the bend of the San Andreas fault, “We end up with a very similar sort of structure (as in Pakistan) with a big fault and a basin with a lot of people sitting out in front of it... Just like Islamabad, you put LA out right in front of that fault with a nice basin to amplify the shaking.”

She added: “At some point we’re going to have a similar earthquake. Hopefully we’re going to have better buildings.”

Keith Porter, a member of the professional staff in Caltech’s department of civil engineering, and Craig Davis, a water works engineer with LA City Department of Water and Power, highlighted the importance of continual inspection and update of facilities to help minimize the effects of disasters.

Porter helped survey the damage Hurricane Katrina inflicted on New Orleans and Mississippi and found that the type of damage mirrored that caused by earthquakes. “Earthquakes and hurricanes are inevitable,” he said. “Losses are not.”— The Guardian/Whittier Daily News

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