In August 2011, five months after large parts of northeast Japan were devastated by a magnitude-9 tremor and the tsunami that it triggered, scientists at the Tokyo Earthquake Research Institute released the results of a deeply worrying study.

Their research showed that the March 11, 2011, quake had exerted tremendous pressures in the tectonic plates that meet directly beneath Tokyo, significantly raising the possibility of two or more focal points on the plate boundaries shifting simultaneously. That, they estimate, could result in an earthquake with a magnitude of 7.3.

And while that is smaller than the quake that struck the Tohoku region, the impact on a densely populated and built-up area could be catastrophic.

"We estimate that 10,000 people would die and the economic loss would be around 1 trillion US dollars," said Naoshi Hirata, a researcher at the institute.

And that estimate might be on the conservative side, given that more than 19,000 people died in the March 11 earthquake and the subsequent tsunami.

"Even before March, we estimated that there was a 70 percent likelihood of a major earthquake affecting Tokyo at any time within the next 30 years," said Hirata, who is also a member of the government's Earthquake Research Committee.

"That is a very high probability and effectively means that there will be a major disaster here, although we cannot at the moment make a more accurate prediction of when it might strike."

'Be prepared'

"All we can say is that individuals, companies, schools and the national and local governments should be prepared," he added.

That warning has been heard.

In late December, property owners in the key central business district that encompasses the central Tokyo areas of Otemachi, Marunouchi and Yurakucho announced plans for a disaster management facility to prepare for any form of disaster and to equip it with medical facilities, emergency accommodation, electricity and a warm refuge for anyone unable to get home in the aftermath of a major quake.

"We have taken several new measures to deal with natural disasters, although as a property management company we already had essential disaster prevention plans in place," Ryuichiro Funo, a spokesman for Mitsubishi Estate Co., told DW.

The company has 35 large-scale office buildings in the Marunouchi district, with some 230,000 people working in the properties.

"We already had stockpiles of food, water, blankets and other emergency supplies before the March 11 disaster, but we have since increased the amount ready to be used," he said.

"We have learned that our buildings are strong enough to withstand large earthquakes, although we have since installed new monitoring systems linked to computers that are able locate any physical damage to our structures."

Long-life generators

Mitsubishi Estate is also planning a number of new buildings in the area and, thanks to the lessons it has learned, will be installing emergency generators with the capacity to operate for up to 72 hours. At present, back-up power systems have a maximum operational life of 48 hours.

Other buildings have their own water purification plants to provide drinking water as well as barriers and waterproof doors to prevent against flooding. Mitsubishi Estate also uses a seismically resistant fiber optic network to preserve communications links and is pushing ahead with an Emergency Disaster Management system that will be able to mobilize around 200 people with a wide array of skills and expertise in the immediate aftermath of a major disaster.

Further measures are being planned throughout the metropolis. The Tokyo Metropolitan Government is planning to deploy emergency generators in 60 parks and cemeteries throughout the city, with a test project scheduled to get under way in Adachi Ward in the next few years.

The operator of the Tokaido Shinkansen "bullet trains" has also announced that it is reconsidering its priority of designing its vehicles for optimum speed to give them shorter braking distances. Central Japan Railway Co. said its new N700A models, which go into service in February, will be able to come to a complete halt in a shorter time in the event an earthquake strikes.

'Floating' house

The national government is in the process of introducing new rules that will require the owners and operators of large buildings - including hospitals and schools - to carry out frequent earthquake resistance tests, while one firm has come up with an ingenious method of protecting buildings from the violent shaking of an earthquake, fitting homes with giant air-bags that enable them to "float" through the tremors.

When an earthquake strikes, a sensor detects the movement and activates a compressor that pumps air into bags beneath the building within one second, according to officials of Air Danshin Systems Inc. The air is sufficient to lift the structure off its foundations and maintain it at a height of about 3 cm for as long as the ground continues to shake.

A valve that is within the structure controls the amount of air that is being forced beneath the building to keep it steady and upright.

Once the 3-million-yen (33,500-US-dollar) system senses that the tremor has ended, the air is gently let out of the bags and the house settles back onto its foundations.

The disaster of nearly two years ago has also changed attitudes among ordinary people.

Earthquake drills at schools in the coastal city of Yokohama, for example, have changed. Before March 11, teachers drummed into their charges the mantra of "Don't run, don't push and don't speak." To that, they have added a new rule: Don't go back.

The number of people who survived the first or second minor tsunami, only to be killed when they returned to their homes by larger subsequent waves triggered by the massive 2011 earthquake will never be known, but it is yet another lesson that has been learned the hard way.