Earthquake Countermeasure and Seismic Isolation Technology in Japan
The massive Tohoku earthquake that struck Japan on March 11, 2011 was a reminder of the seriousness of seismic activity in Japan. It can, and does, strike anywhere in the country, and in fact, many experts predict that the next big earthquake may hit in the middle of the east coast of the country, near Tokyo.
So, as one of the most technologically advanced countries in the world, it should be no surprise that truly remarkable technologies have been developed and put to use, here in Japan, to protect people and assets from the effects of earthquakes.
Earthquake Countermeasure Technology
There are roughly 3 primary technologies employed to combat the effects of earthquakes, with many variations and combinations of these:
Resistance – Engineering a structure to improve the ability of pillars and beams to withstand seismic force – basically architecting structures to absorb the force of an earthquake.
Damping – A number of methods are employed here such as rubber fittings or “viscous dampers” under structures to help absorb the force of shocks.
Seismic Isolation – Here, systems are put in place between buildings and their foundations, eliminating direct transmission of earthquake shocks to buildings by compensating for the movement of the ground below, passing on literally little to no movement to buildings or mounted objects above.
I had the good fortune of seeing, first-hand, a demonstration of Seismic Isolation technology recently at the 23rd FINETECH JAPAN convention at Tokyo Big Sight and I was absolutely impressed.
The demonstration was given by THK Co., Ltd. of Nishi-Gotanda, Tokyo. On display was their Seismic Isolation Table (Model TSD). It was a platform of about 1.5 square meters with a server rack on top of it. The plate under which the table was sitting was moving to simulate the magnitude of the Great Tohoku earthquake of March 11, 2011, in the area of the greatest shaking. The Isolation Table was absorbing virtually all of the movement below, illustrated by a bottle of water mounted on the table – there was virtually no sloshing of the water inside.
This isolation table showed how this technology is put to use to protect important delicate machinery, robots, server racks, computer systems, etc. It is also used by wine collectors to protect their collections and by art museums to protect priceless artwork.
THK Seismic Isolation Table
THK’s technology is also put to use in Seismic Isolation foundations for new buildings. The idea is the same, on a large scale. Whole buildings are isolated from the shaking below on a series of seismic isolation mounts. This technology is optimal for structures up to 10 stories high, and is effective, in conjunction with Damping Systems, in protecting high-rise buildings.
THK’s Seismic Isolation for buildings
Seismic Isolation – How it works
THK’s core expertise is using ball bearings to develop “Linear Motion Systems” – converting a mechanical component’s linear motion into a “rolling” motion, which greatly improves the fluidity and smoothness of movement.
They have developed high-precision rolling tracks, using ball bearings, in various combinations, to allow for motion in any lateral direction as dictated by an earthquake. Vertical motion is also compensated for as the table or foundation provides a solid base to be anchored to as motion continues. Once movement has ceased, the systems have springs that are used to restore original positioning.
THK’s technology is used under new buildings built in Japan and other seismically active areas. Based on the company’s ball bearing and high precision movement technology, building positioning literally compensates for various lateral and vertical movement of the ground, dramatically dampening the perceived movement and shaking caused by earthquakes and reducing potential damage.
A couple high profile examples of this technology in use:
The National Art Center, Tokyo
Aichi Prefectural Office, Nagoya
Current Use and Future Potential
Earthquake countermeasure technology is in use in modern construction in Japan, and the rule-of-thumb is generally that the newer the building, the more sophisticated the employed technology.
There is no doubt that this technology made a difference during the 2011 Tohoku earthquake. Sendai, the largest city in Tohoku, and quite close to the center of the earthquake had relatively little structural damage among its office and residential buildings.
Resistance and Damping technology are by far the most employed earthquake countermeasure technologies, however Seismic Isolation is gaining ground quickly after having proved itself as particularly effective in the 2011 Tohoku earthquake.
Meanwhile, many areas of the world share the same fate as Japan, with disastrous earthquakes hitting recently in New Zealand, Italy, China, Chile, Iran, Indonesia – with more to come.
Seeing the amount of destruction around the world from earthquakes that are often of much lesser magnitude than those in Japan, I think that use of Japanese earthquake countermeasure technology could see an increase in the future around the world. This is an area of Japanese technology that should have a lot of future potential, but whether the market overseas can be properly developed remains to be seen.
Special thanks go to Toshio Saiki and Tomoko Kayaki of THK Co., Ltd. for assisting me with information and pictures as I assembled this story.