US builders rarely use designs that withstand earthquakes
When the shaking started at 5:46 a.m., Yasuhisa Itakura, an architect at a big Japanese construction company in Kobe, was sitting at his desk finishing a report he had toiled over all night. His office swayed, but the books stayed on their shelves and nothing fell off his desk.
“I thought to myself, this earthquake is not that big,” Itakura said.
It was, in fact, catastrophic. The Great Hanshin earthquake of Jan. 17, 1995, killed more than 6,000 people in and around the industrial port city.
Itakura had been cushioned from the violence of the earthquake because his three-story office building was sitting on an experimental foundation made from rubber – an early version of an engineering technique called base isolation.
The technique that protected Itakura’s building is used in roughly 9,000 structures in Japan today, up from just two dozen at the time of the Kobe earthquake. Thousands of other buildings in the country have been fitted with shock-absorbing devices that can greatly reduce damage and prevent collapse.
Chile, China, Italy, Mexico, Peru, Turkey and other countries vulnerable to earthquakes have adopted the technologies to varying degrees.
But with notable exceptions, including Apple’s new headquarters in Silicon Valley, the innovations have been used only sparingly in the United States. Seismic safety advocates describe this as a missed opportunity to save billions of dollars in reconstruction costs after the inevitable Big One strikes.
Earthquakes are of course natural phenomena. But the amount of damage they cause is a function of decisions made by politicians, engineers and business executives. Japan and the United States, two of the world’s most technologically advanced countries, have the same problem – how to protect people and society from earthquakes – and yet they have responded in very different ways.
Japan, through both government mandates and its engineering culture, builds stronger structures capable of withstanding earthquakes and being used immediately afterward. The United States sets a minimum and less protective standard with the understanding that many buildings will be badly damaged.
The two approaches reflect different attitudes toward risk, the role of government and collective social responsibility. Analogous to America’s debate over health insurance, the U.S. philosophy has been to make more resilient buildings an individual choice, not a government mandate.
“Do we want to be more like Japan and are we willing to pay the price?” said Joyce Fuss, president of the Structural Engineers Association of California. “A lot of people would say ‘no’ and maybe some people would say ‘yes.’ ”
Inherent in the U.S. approach to seismic engineering is a risk calculation: Many American engineers operate on the assumption that a building, which might be used for 50 years before it is torn down and replaced with a new one, has a relatively small chance of being hit by a huge earthquake.
“If you spend the money today and the earthquake happens tomorrow, then congratulations, you’ve done a good job,” said Ron Hamburger, an American structural engineer who is perhaps the leading authority on the building code. “But the fact is, truly significant damaging earthquakes will affect a place like San Francisco or Los Angeles maybe once every 100 to 200 years.”
“How lucky do you feel?” he added.
In cities like San Francisco, where the median price of a home is well above $1 million, the notion of making construction costs even more expensive is likely to be unpopular, even if the goal is to preserve the city in the long run.
Large earthquakes are around 10 times more common in Japan than in the continental United States, according to Hiroo Kanamori, an emeritus professor of seismology at the California Institute of Technology.
But seismic history suggests that California may be due for large earthquakes, which often come in clusters.
In Northern California, the past five major earthquakes along the Hayward fault, the jagged crack in the earth that runs through the heavily populated cities of Berkeley and Oakland across the bay from San Francisco, have occurred on average every 140 years.
The last one was 151 years ago. (Seismic history has also shown that predicting earthquakes is a fool’s errand.)
The last major earthquake in the contiguous U.S., which caused $20 billion of damage to the Los Angeles area, was a quarter of a century ago.
“The land has been peaceful in America,” said Masayoshi Nakashima, president of the International Association for Earthquake Engineering. “Young generations in particular are not necessarily familiar with the reality of earthquakes.”
The debate over whether to build more resilient buildings in the United States has been held largely out of public view, among engineers and other specialists.
But at stake is whether places like Silicon Valley, Seattle, Salt Lake City, San Francisco or Los Angeles might be forced to shut down after a direct hit – and for how long.
A federal study last year found that a quarter of the buildings in the San Francisco Bay Area would be significantly damaged after a magnitude-7 earthquake, a disaster that would be compounded by the fact that 9 out of every 10 commercial buildings and 8 out of 10 homes in California are not insured for earthquakes.
“Cities won’t be usable for many months, if not years,” said H. Kit Miyamoto, a member of the California Seismic Safety Commission, a government body that advises the state Legislature and the governor on earthquake issues. “Throwaway buildings equal a throwaway city.”
In a severe earthquake, most American buildings are designed to crumple like a car in a head-on collision, dissipating the energy of the earthquake through damage. The goal is to preserve lives, but the building – like a car after an accident – may be useless.
Hamburger, the structural engineer, estimates that half of all buildings in San Francisco could be deemed unoccupiable immediately after a major earthquake.
Some cities like San Francisco are considering rules that would require buildings to be more rigid, similar to those in Japan. There is no such thing as earthquake-proof construction, but experts say American buildings could be much more resilient for little additional cost.
A multiyear federal study concluded that fixing buildings after an earthquake costs four times more than building them more strongly in the first place. The United States is losing an estimated $4 billion for every year that it delays a stronger building code for earthquakes, the study calculated.
Miyamoto, who was raised in Japan but now lives in California, said there was increasingly sharp disagreement between Japan and the United States over seismic engineering.
“The Japanese are completely flabbergasted about how we design out here,” he said.
Protecting tall buildings
from earthquakes is among the highest-stakes endeavors for engineers. The collapse of even one skyscraper could have catastrophic effects. Tall buildings are also perhaps the biggest bone of contention between American and Japanese engineers.
Most new high-rises in the United States are built around a reinforced concrete core, a technique that Japanese engineers shun because they say it performs unpredictably in an earthquake. Tall buildings in Japan are almost always built with steel.
Japan, of course, still has many vulnerabilities, some of which were made clear when the 2011 Tohoku earthquake created a tsunami that breached sea walls, killing an estimated 16,000 people and spreading radiation from a damaged nuclear reactor.
The country has many older buildings constructed before major changes to a 1981 building code, and even the country’s seismic innovations are of varying quality and effectiveness, as highlighted by revelations last year that a manufacturer of seismic shock absorbers falsified its performance data.
But overall, Japanese engineers say, earthquakes over the past two decades have proved the effectiveness of the country’s stricter regulations and innovations.
Kobe and the Tohoku earthquake of 2011 led to a surge in demand for more robust buildings, with consumers willing to pay a premium for the latest technologies. One company has developed inflatable air bags that deploy underneath a wooden home when a large earthquake is detected.
Of Japan’s 9,000 baseisolated structures, 4,300 are multistory buildings, many of them offices, condominiums and government buildings, and 4,700 are houses, according to the Japan Society of Seismic Isolation.
Base isolation is advertised on Japanese television and on the Tokyo subway, touting the seismic systems of newly constructed condominiums. Nice Corp., a Japanese construction company, says a seven-story base-isolated building costs 13% to 15% more than a conventional one.
Amarnath Kasalanati, the associate director of the Pacific Earthquake Engineering Research Center at the University of California, Berkeley, says it is paradoxical that more buildings in the United States do not use innovative seismic technologies, since American scientists and engineers were early leaders in the field.
Kasalanati estimates that there are 175 baseisolated buildings in the United States, mostly museums, hospitals and older buildings like the city halls of San Francisco and Los Angeles that were retrofitted with isolators.
One U.S. company that helped develop seismic isolation devices has shipped 70% of the 20,000 devices it has produced overseas.
One notable building in the United States that uses the devices is Apple’s giant new headquarters in Silicon Valley.
Steve Jobs, the Apple co-founder, died before construction began on the building. But when he introduced plans for the circular, glass-sheathed structure, he described it as a “little like a spaceship.”
As seen on a rare tour, the four-story orb, which holds 12,000 people and is about as wide as the Pentagon, is the RollsRoyce of base-isolated buildings.
The building, which has a concrete foundation that resembles a bathtub, is not attached to the ground – if cranes or helicopters existed that were powerful enough, they could lift it up.
At the base of the building’s nearly 700 support columns are stainless steel pucks that sit on top of massive steel saucers. When an earthquake causes the ground to shake, the pucks slide across the saucers as much as 4 feet, slowed by friction.
The net effect for occupants is that when the ground jolts back and forth, the building moves significantly less.
One of the designers of the building was Jony Ive, the man who was responsible for the look and feel of Apple products such as the iPhone and iPad.
A native of Britain, Ive said he found the threat of earthquakes “utterly alarming” when he moved to California in the 1990s and was surprised by the Californian nonchalance toward them.
Ive said he and Jobs never considered using a conventional foundation for the building.
“We would have seen it as utterly bizarre not to protect our investment,” he said.
Los Angeles City Hall was retrofitted with base isolators to help cope with future earthquakes. But most US buildings in quake-prone regions lack earthquake-resistant innovations. One reason is that builders aren’t required to use them.