Earthquake alarms ring at Tokyo’s metropolitan government headquarters, sending workers running for cover. Across the city, workers in another tower react to a fire alert. It’s all part of a citywide drill organized by the government last month.
Scientists warned the likelihood of a big quake striking Tokyo has increased since the huge turbulence tsunami in northern Japan last March. Shinichi Sakai is from the Earthquake Research Institute at Tokyo University.
“When we did the calculations, tectonic activity was up about 6 or 7 times. At that point in time, we established there was a 98% chance of quake within 30 years or for the next 4 years, it would likely be 70%.”
Animation models are being used to predict the potential damage from a large quake determining the locations of weak buildings as well as fire hazards and evacuation bottlenecks. Official estimates say a 7.3 magnitude quake in Tokyo could cause 11 thousand casualties and destroy 850 000 buildings.
At Tokyo’s Shimizu Corporation, scientists work on cutting edge construction technologies. This building is supported on hardened rubber dampers. Cameras captured the momenta of last year’s giant quake struct, the so-called seismic isolation is easy to see.
Other technologies developed here include suspending buildings from a central pillar which helps to absorb seismic shocks, and partially floating buildings on water which have been showing to reduce movement significantly.
Masaaki Saruta is the chief engineer at Shimizu. He says Tokyo is better prepared than most cities.
“Recently constructed buildings are strong enough to withstand a big earthquake. Even older buildings in Tokyo have been strengthened. I would not say there will be no destruction at all, but we are prepared for this.”
Amateur video posted on line shows skyscrapers in Tokyo swing alarmingly in the earthquake last March. Saruta says it’s part of the design.
“But basically you do not need to worry about a building even it is swinging. What I mean is you would expect the tall building to swing like that because of the design.”
Last year’s quake, 300 kilometers to the north, shut down much of Tokyo, alerting authorities to prepare for a big earthquake even closer to this huge metropolis.