Editor's Note: Design for Impact is a series highlighting architectural solutions for communities displaced by the climate crisis, natural disasters, and other humanitarian emergencies.
CNN –
After a magnitude 7.5 earthquake struck Ishikawa Prefecture on Japan's west coast on Monday, scenes of buildings reduced to rubble were broadcast around the world this week.
The full extent of the damage is still unknown. According to authorities, at least 270 houses were destroyed in the region, but the final figure is likely to be significantly higher. This figure does not include, for example, Suzu or Wajima, a town of more than 27,000 residents located just 32 kilometers from the quake's epicenter, where the fire department said about 200 buildings burned down, according to public broadcaster NHK.
These reports speak to the personal tragedies faced by many residents of the region. Although no two seismic events are directly comparable, earthquakes of similar magnitude in other parts of the world – such as a magnitude 7.6 quake that caused over 30,000 buildings to collapse in Kashmir in 2005 – have often caused far greater destruction.
In contrast, Ishikawa may have gotten off lightly, according to Robert Geller, professor emeritus of seismology at the University of Tokyo.
“Modern buildings seemed to be doing very well,” he told CNN the day after the Japan earthquake, pointing out that older homes “with heavy tiled roofs” appeared to have fared the worst.
“Most single-family homes, even if they were damaged, did not completely collapse,” he said.
A saying in seismic design is that earthquakes don't kill people – buildings do. And in one of the world's most earthquake-prone countries, architects, engineers and urban planners have long sought to protect cities from major earthquakes through a combination of ancient knowledge, modern innovation and ever-evolving building codes.
Trevor Mogg/Alamy Stock Photo
A building in Osaka, Japan that has been reinforced to protect against earthquakes.
From large-scale “dampers” that swing like pendulums in skyscrapers to systems of springs or ball bearings that allow buildings to sway independently of their foundations, technology has advanced dramatically since the Great Kanto earthquake struck large parts of Tokyo and Yokohama were razed just over 100 years earlier.
But innovation is usually based on a simple, long-understood idea: that flexibility gives structures the greatest chance of survival.
“Many buildings, especially hospitals and important critical structures, are mounted on these rubber mounts (bearings), allowing the building itself to sway,” said Miho Mazereeuw, associate professor of architecture and urban design at the Massachusetts Institute of Technology (MIT), who wrote in her upcoming book “Design Before Disaster” examines Japan’s culture of preparedness.
“Conceptually, it all boils down to the idea that you don’t resist the movement of the earth, but let the building move with it.”
This principle has been used in Japan for centuries. For example, many of the country's traditional wooden pagodas have survived earthquakes (rather than falling victim to fire or war), although this has not been the case with modern structures. Take, for example, the 180-foot (55-meter)-tall pagoda of Toji Temple, built near Kyoto in the 17th century. It is known for having survived the Great Hanshin Earthquake of 1995, also known as the Kobe Quake, unscathed, while many nearby buildings collapsed.
Ivan Marchuk/Alamy Stock Photo
The five-story 17th-century pagoda at Toji Temple in Kyoto.
Japan's traditional architecture shares many similarities with that of neighboring Korea and China, but differs in some ways due to the country's higher frequency of earthquakes.
In particular, the remarkable survival rate of pagodas has long been attributed to “shinbashira” – central columns made of tree trunks that have been used by Japanese architects for at least 1,400 years.
Whether anchored to the ground, resting on a beam, or suspended from above, these columns bend and bend as the building's individual floors move in the opposite direction of their neighbors. The resulting snaking motion – often compared to that of a slithering snake – helps counteract the force of the tremor and is supported by interlocking joints and loose fittings, as well as wide eaves.
Not all buildings in modern-day Japan resemble pagodas, but skyscrapers do.
Although the country imposed a strict height limit of 31 meters (102 feet) until the 1960s due to the dangers of natural disasters, architects have been allowed to build taller ever since. According to the Council on Tall Buildings and Urban Habitat, there are now more than 270 buildings in Japan taller than 150 meters (492 feet), the fifth largest in the world.
Using steel skeletons to add flexibility to the notoriously stiff concrete, high-rise designers have been further emboldened by the development of large-scale counterweights and “base isolation” systems (such as the rubber mounts mentioned above) that act as shock absorbers.
The real estate company behind Japan's new tallest building, which opened last July in Tokyo's Azabudai Hills project, claims its earthquake-resistant design features – including large-area dampers – would allow companies to “continue operations” in the event of a seismic event “. as strong as the record magnitude 9.1 earthquake in Tohoku in 2011.
Jun Sato/WireImage/Getty Images
The largest tower in Tokyo's Azabudai Hills project is now Japan's tallest skyscraper.
But in the many places in Japan without skyscrapers like Wajima, earthquake resistance is more about protecting everyday buildings — homes, schools, libraries and shops. And in this respect, Japan's success was as much a matter of policy as it was technology.
On the one hand, Japan's architecture schools — perhaps because of the country's history of natural disasters — have ensured that students are grounded in both design and engineering, said Mazereeuw, who also directs MIT's Urban Risk Lab, a research organization that studies seismic and climate risks examines cities.
“Unlike most countries, Japanese architecture schools combine architecture with civil engineering,” she said, adding that in Japan the two disciplines “are always linked.”
Japanese officials have also tried to learn from every major earthquake the country has faced over the years by conducting detailed investigations and updating building codes accordingly.
This process dates back to at least the 19th century, Mazereeuw said, explaining how the widespread destruction of new European-style brick and stone buildings in the Mino-Owari earthquake of 1891 and the Great Kanto earthquake of 1923 led to new urban planning laws and urban buildings.
Hulton Deutsch/Corbis/Getty Images
After the Great Kanto Earthquake of 1923, Tokyo was in ruins.
The gradual development of building regulations continued throughout the 20th century. But a code introduced in 1981 called “Shin-Taishin,” or “New Earthquake Resistance Building Standard Amendment” — a direct response to the offshore Miyagi earthquake three years earlier — proved to be a turning point.
Among other things, the new standards place higher demands on the load-bearing capacity of new buildings and require greater “story drift” (how many floors can move relative to each other). They have proven so effective that homes built to pre-1981 standards (known as “kyu-taishin” or “pre-earthquake resistance”) can be significantly harder to sell and more expensive to insure.
The first real test of the regulations came in 1995, when the Great Hanshin earthquake caused widespread destruction in the southern part of Hyogo Prefecture. The results were clear: According to the Global Facility for Disaster Reduction and Recovery, 97% of the collapsed buildings were built before 1981.
Innovation and preparation
The 1995 quake sparked a nationwide initiative to renovate older buildings to 1981 standards, a process the city government encouraged through subsidies. Since then, innovation has continued, with Japanese architects often leading the way when it comes to seismic design.
Kimimasa Mayama/Bloomberg/Getty Images
A seismic isolation system on a column head at engineering firm Shimizu Corporation's research facility in Tokyo, Japan.
For example, one of the country's best-known architects, Kengo Kuma, worked with textile company Komatsu Matere in 2016 to develop a curtain made of thousands of woven carbon fiber rods that anchors the company's headquarters – just 85 miles from the epicenter of Monday's quake. like a tent on the ground (picture above). More recently, he co-designed a kindergarten building in southern Kochi Prefecture that features an earthquake-resistant checkerboard wall system.
Elsewhere, leading Japanese architects such as Shigeru Ban and Toyo Ito have pioneered the use of cross-laminated timber (CLT), a new type of engineered wood that its proponents believe could transform the way high-rise buildings are built . (The first large-scale earthquake simulator test of an engineered wooden tower took place last spring at the University of California, San Diego. Whether plans for a 1,148-foot-tall CLT tower in Tokyo, proposed by Japanese firm Sumitomo Forestry, will ever be viable, according to Japan's strict Complying with building codes is another matter.
Eric Lafforgue/Art in Us All/Corbis/Getty Images
An earthquake-resistant column used in the design of an old wooden house in Miyama, Kyoto Prefecture.
Advanced computer models also allow designers to simulate earthquake conditions and build accordingly. Yet, fortunately, the limits of most disaster-resistant buildings have never been tested.
“There are many high-rise buildings and a lot of effort has been put into making them safe, but these designs are largely based on computer simulations,” said Geller of the University of Tokyo. “We may not know whether these simulations are accurate or not (until) a large earthquake happens. If even one of these high-rise buildings collapses, there could be major damage.”
So the question that has long troubled Japan's engineers and seismologists remains: What if a large earthquake were to directly hit a city like Tokyo, which officials in the Japanese capital have warned is more likely to happen in the next 30 years 70%?
“Tokyo is probably reasonably safe,” he added. “But there’s no way to know for sure until the next big earthquake actually happens.”
CNN's Eric Cheung and Saki Toi contributed to this report.