How Japan learns from its earthquakes and tsunamis
The 1923 earthquake that devastated Tokyo spawned a nationwide effort to prepare for future quakes. Here's a Monitor story that shows how the survivors of the Tokyo disaster helped that cause.
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“You must not think earthquakes are fun,” yells one simulator-keeper, Katsumi Hirayama, to a gaggle of giggling school girls as they are jolted. He instructs them how to turn off the gas and get under a table. For taking a shake, each girl receives a packet of vacuum-packed rice crackers to keep as emergency food.Skip to next paragraph
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The mock quake is not always convincing. “When a real one comes, I won’t live anyway. So why bother?” says Jun Murayama as she steps off the truck. “Even experienced swimmers can drown.”
Since 1980, the Japan Meteorological Agency (JMA) has placed more than 130 sensors inside mountains and on the ocean floor to pick up geologic vibrations that might signal an earthquake in the region south of Tokyo. The electronic data are monitored by computers and two persons, 24 hours a day.
But the ability to predict a quake by scientific means has not been proved. “We don’t know if we will succeed. But can we afford not to try?” says Dr. Nobuo Hamada, the center’s deputy head.
If unusual signals are detected in several places, six prominent seismologists would be rushed to the agency. If all agree that a quake is imminent, they would then ask the prime minister to call for people to evacuate the most vulnerable areas.
Since 1923, the government has set strict construction codes to make buildings, bridges, dams, and other structures as seismic-proof as possible.
Some new buildings have “rubber feet” in the base to absorb shock. A few skyscrapers have a flexibility that allows them to sway for an hour after a tremor.
Yet no one knows for sure if all the structures were correctly built, or whether the designs themselves will actually work.
“We just don’t know,” says Chikahiro Minowa, chief engineer at a government quake-simulator center outside Tokyo. The center, built in 1970, uses a 180-ton floating table to test the seismic-resistance of new architectural designs.
“It’s difficult to test a whole structure,” he adds. “We’ll just have to wait for a big earthquake.”
Japan’s most active constructor of high-rises, Kajima Corp., has invented a device to reduce the sway of tall buildings during a quake. A four-ton mass of steel sits atop an 11-story experimental structure in Tokyo and helps to “suppress” sway by quickly moving in the opposite direction with computer-driven hydraulics.
“Previous ideas were to protect buildings,” says Akiko Oda, a company official, “but now comfort is pursued.”
Quake-veteran Uchibaba says all the precautions are useless.
“The effects of the next quake will be much worse because of the way we live today. Cars will jam roads, gas stations will explode, and people won’t be able to move.
“Japan is not ready for another quake, not at all. Even if you prepare, the real thing is different from anything that you can expect,” says one who has lived to tell about it.