Real estate developers are employing early warning technology that shuts down elevators in their buildings in central Tokyo ahead of the arrival of seismic waves from earthquakes striking in remote regions. 

The new technology also allows swift damage estimates to be made for a head start on recovery operations. 

Such preparedness at the buildings in the densely packed urban center is increasing in importance as these structures are expected to serve as bases to combat and mitigate damage from quake disasters.

Mitsubishi Estate Co. has installed in its high-rise buildings the Yuremasu network, the emergency earthquake warning system that was developed by Mieruka Bousai Co., a Tokyo technology start-up.

Earthquakes generally produce two types of seismic waves in the initial stage.

One is “preliminary” waves that travel about 7 kilometers per second, known as P waves. The other is S waves, or “secondary” waves, which cover about 4 km per second. While P waves cause slight tremors, S waves cause more ground shaking.

When the epicenter of a quake is located close to a given area, these two waves arrive there at approximately the same time.

But the farther the quake is centered, the longer it takes S waves to reach the designated area.

This means if P waves are captured early, it may provide precious seconds to act before significant shaking is felt.

Mitsubishi Estate introduced seismometers and the Yuremasu system to buildings the company manages in Yokohama, Shisui in Chiba Prefecture, and Sano in Tochigi Prefecture, and elsewhere.

The purpose is to detect seismic waves immediately by setting up outlying monitoring points close to active seismic faults.

Data from the seismometers will be fed into the network connecting 14 buildings in the capital, including Mitsubishi Estate’s 36-story Marunouchi Building in front of Tokyo Station.

As soon as a structure close to the earthquake’s epicenter registers P waves, the Yuremasu system is programmed to instantly calculate the time before S waves reach buildings in remote locations and the intensity of the swaying that will likely follow there.

For example, a simulation of an earthquake centered near Gotemba, Shizuoka Prefecture, showed that three seconds after the quake, an alert will be issued that major tremors will likely occur in 18 seconds at the Marunouchi Building around 80 kilometers away.

The Yuremasu also incorporates the Japan Meteorological Agency’s earthquake early warning and forecast system for long-period earthquake ground motion.

It responds to signals that come first so that elevators will stop at the nearest floor to avoid having people trapped inside.

But the agency’s earthquake early warning system sometimes does not come in time for a major shock, depending on where people are and geological conditions of the site.

The Yuremasu system is drawing attention for supplementing the agency’s setup.

Mieruka Bousai, founded in 2013, has a staff of eight employees, including former employees of Nippon Telegraph and Telephone Corp. The employees are all aged 60 or older and hold a deep expertise in the telecommunications field.

“We are intending to bolster preparedness to respond to a powerful earthquake predicted to directly strike Tokyo with the network of our system to be broadened to include transportation systems and other facilities,” said Ryuji Matsuo, president of Mieruka Bousai.

The Shin-Marunouchi Building, a 38-story tower also near Tokyo Station, stands at the site where a makeshift medical center was set up to treat survivors of the Great Kanto Earthquake. In the 1923 earthquake that directly jolted and devastated Tokyo, an estimated 105,000 people were either killed or left unaccounted for.

Toshio Oba, a senior official at Mitsubishi Estate’s Marunouchi business management department, noted that about 350,000 people work in the Marunochi district, where headquarters of major companies as well as a crucial transport hub are located.

“If the district were damaged, it would have far-reaching implications for all of Japan,” he said. “Facilities in the district should play a central role in containing the disaster.”

The Yuremasu system has been deployed not only in tall buildings but also in chip-making factories to protect production equipment.

Sony Semiconductor Manufacturing Corp., based in Kikuyo, Kumamoto Prefecture, has installed the system in its plant in Kikuyo town to protect sophisticated equipment and products from a major earthquake.

When twin powerful earthquakes shook Kumamoto Prefecture only days apart in 2016, it took the company some time to restore the impacted precision equipment.

After adopting the system, there was an occasion where the equipment was safely halted before the strong shaking hit. 

The company also installed the network in production centers in four prefectures, including Kagoshima and Yamagata.

Some production centers have enlisted the cooperation of prefectural and municipal governments as well as airports so that seismographs can be installed at many sites.

“We are hoping to reduce damage to our respective facilities by sharing data,” said a public relations official of Sony Semiconductor Manufacturing of the effort.

Mori Building Co., based in Tokyo’s Minato Ward, puts much effort into a response to deal with long-period ground motions, which causes slow, major swaying. 

A powerful earthquake can induce long-period ground motions in locations far from its epicenter.

When such vibrations resonate with the cycles of tall buildings’ swaying, it results in significant structure movement over a long duration, thus heightening the likelihood of damage.

“There is the danger that the upper floors of towers could experience larger and more prolonged shaking when a major earthquake centered in a remote region strikes, rather than one that directly hits the capital,” said Masaharu Yasuda, an official with Mori Building’s structural engineering department.

Assessing which floors were most impacted in the buildings cannot be done quickly if people were dispatched to each floor to survey damage after the shaking subsided.

Mori Building’s response to this conundrum is the e-Daps system, or the Earthquake Damage Presumption System.

The system automatically estimates the acceleration of swaying on each floor and deformation in a building based on readings of seismographs installed on some floors and the building’s structural properties.

It can also detect long-period ground motions at an early stage and show which floors were most affected, according to Mori Building officials, enabling swift assessment of damage and efficient rescue operations.

The e-Daps technology was introduced to Roppongi Hills Mori Tower in the ward for the first time in 2013.

Seismometers were placed on five levels: the sixth basement, first floor, 20th floor, 40th floor and the top floor of the 54-story structure.

About 20 skyscrapers and 10 or so low- to mid-rise buildings in Tokyo are now equipped with this system.

Mori Building began developing e-Daps after the company spent several days surveying damage to its buildings in response to inquiries from tenants when Tokyo was rocked by the 2011 Great East Japan Earthquake.

When the devastating earthquake occurred in the Noto Peninsula in January, the e-Daps system assessed the shaking in the buildings the company manages in Tokyo and damage to those structures only five minutes after the quake.

Its data showed that minor swaying was felt for nearly 10 minutes in high-rises, according to the company.

The Roppongi Hills neighborhood will serve as a shelter for stranded people in the event of a natural disaster.

The company said it is important to quickly determine which part of the neighborhood and floors of the buildings are safe.

The JMA releases information on efforts in the private sector to alleviate damage while utilizing the agency’s earthquake early warning system.