Japan prepares for once-in-a-century earthquake; is it necessary?

As tremors shook the ground in parts of western Japan on Thursday (8), local and national government bodies sprang into immediate action.

Meteorologists met and issued a temporary tsunami warning. A special committee warned that another “major earthquake” could occur within the next week – the first time in the agency’s history that such a national warning had been issued.

High-speed trains were slowed as a precaution, causing travel delays, and the country’s prime minister canceled his overseas trips.

In the end, the government lifted most warnings and reported no significant damage from the magnitude 7.1 earthquake.

However, much of the country remains on high alert, bracing for a possible emergency during what is typically the peak travel season during the summer holidays — reflecting Japan’s laser-sharp focus on earthquake preparedness.

However, some experts have questioned whether such a warning is necessary or even accurate – and whether it risks diverting resources away from communities considered to be at lower risk.

Japan is no stranger to severe earthquakes. It is located in the Ring of Fire, an area of ​​intense seismic and volcanic activity on both sides of the Pacific Ocean.

“Japan is situated on the boundaries of four tectonic plates, making it one of the most earthquake-prone areas in the world,” said Shoichi Yoshioka, a professor at Kobe University in Japan.

“About 10 percent of earthquakes of magnitude 6 or greater occur in or near Japan, so the risk is much higher than in places like Europe or the East Coast of the United States, where earthquakes are rare,” Yoshioka added.

The worst earthquake in Japan’s recent history was the 9.1-magnitude Tohoku earthquake in 2011, which triggered a massive tsunami and a nuclear disaster. About 20,000 people died.

Then there is the looming threat of the Nankai Trough mega-earthquake – the most powerful of its kind, with magnitudes that could exceed 9. Seismologists say this could potentially occur within a few decades, although the science is still debated.

The Japanese government has warned of a possible Nankai Trough earthquake for so many years that the possibility of it occurring has become common knowledge.

But it’s also controversial — with some scientists arguing that it’s ineffective to focus only on the small chances of a hypothetical earthquake in a specific part of Japan, especially when other parts of the country face similar threats but receive far less attention.

The “great earthquake”

The Nankai Trough is a 700-kilometer-long subduction zone, which refers to the moment when tectonic plates slide beneath each other.

Most of the world’s earthquakes and tsunamis are caused by the movements of tectonic plates – and the most powerful ones often occur at subduction zones.

In this case, the tectonic plate beneath the Philippine Sea is slowly sliding beneath the continental plate where Japan is located, moving several centimeters each year, according to a 2013 report by the government’s Earthquake Research Committee.

In the Nankai Trough, severe earthquakes have been recorded every 100 to 200 years, according to the committee. The last such quakes occurred in 1944 and 1946, both with magnitudes of 8.1; they devastated Japan, killing at least 2,500 people and injuring thousands, as well as destroying tens of thousands of homes.

Calculating the intervals between each major earthquake, the Japanese government has warned that there is a 70% to 80% chance that Japan will be hit by another Nankai Trough earthquake within 30 years, expected to be between magnitude 8 and 9.

But these predictions, and the usefulness of even making imprecise long-term forecasts, have faced strong resistance from some quarters.

Kobe University’s Yoshioka said the 70%-80% figure is likely too high, and that the data is based on a specific theory, making it potentially more prone to error. However, he has no doubt that “a major earthquake will occur in this area” in the future.

“I tell (my students), the Nankai Trough earthquake will definitely come, whether in your generation or your children’s generation,” he said.

Robert Geller, a seismologist and professor emeritus at the University of Tokyo, was more skeptical, calling the Nankai Trough earthquake a “made-up construct” and a “purely hypothetical scenario.”

He also argued that earthquakes do not occur in cycles, but can happen anywhere and at any time – meaning there is little value in calculating when the next earthquake will occur based on when previous ones occurred.

It’s a point of contention in the scientific community; seismologists have long relied on the idea that stress builds up slowly along a fault between two tectonic plates, then is suddenly released in earthquakes, a cycle known as the “stick-slip” process — though more recent studies have shown that this isn’t always the case.

Even if there is a potential threat on the horizon, the chances are extremely low, with Yoshioka and Geller calling the public safety measures taken over the past week excessive or unnecessary.

It is true that after one earthquake, a second, even larger one can follow — which is why authorities issued the unprecedented warning on Thursday, Yoshioka said.

But even so, the probability of the Nankai Trough earthquake occurring in the next day is low — perhaps rising from a typical risk of 1 in 1,000 to 1 in a few hundred. Still, that is less than 1 percent, he said.

The danger of exaggerating these low probabilities is that “you’d be like[in Aesop’s fable]the lying shepherd and the wolf,” Geller said. “You’d be issuing these warnings with slightly higher than normal probability over and over again, and the public would quickly disbelieve you.”

The population prepares

However, there are no signs of public fatigue yet, with people across the country on high alert. Yota Sugai, a 22-year-old university student, said seeing the warning on television “made me feel a sense of urgency and fear, like a wake-up call”.

After Thursday’s earthquake, he arranged emergency supplies like food and water, monitored online maps for dangerous areas and considered visiting relatives in coastal areas to help them plan evacuation routes.

“The recent New Year’s Day earthquake reminded me that you never know when an earthquake will strike. It made me realize the terrifying power of nature,” he said, referring to the 7.5 magnitude earthquake that struck the Noto Peninsula on Jan. 1 this year – killing hundreds, including dozens who died after the quake from related causes.

Student Mashiro Ogawa, 21, has taken similar precautions, preparing an “emergency kit” at home and encouraging her parents to do the same. She will avoid beaches for now and change furniture in her home, such as moving shelves away from the bed and lowering their height, she said.

“It didn’t seem like a close issue before, but now it feels very real,” he said.

Part of the reason people are taking this so seriously is because of how many earthquakes have rocked Japan and how recent they are. The 2011 disaster left deep scars in the national memory, which are compounded by new major earthquakes every few years.

“Each time we witness the tragic loss of life, buildings being destroyed and tsunamis causing devastation, it leaves a lasting impression of fear,” said Yoshioka of Kobe University. “This fear is shared by many citizens. I think this contributes significantly to Japan’s preparedness.”

That’s why “the Japanese government also emphasizes preparedness to avoid another major tragedy like the 2011 earthquake,” he added. Japan is widely recognized as a world leader in earthquake preparedness and resilience, from its infrastructure and building codes to its relief and rescue systems.

Megumi Sugimoto, an associate professor at Osaka University who specializes in disaster prevention, said preparedness starts at school — with even kindergartens holding evacuation and earthquake drills for young children.

“It’s not just (earthquakes and) tsunamis, but other disasters occur frequently, especially in the summer season,” she said, pointing to typhoons, severe rains and floods. Public awareness and precautions, such as stocking up on emergency supplies, can help protect people from “any kind of disaster,” she said.

But there is still work to be done. Sugimoto and Geller of the University of Tokyo both noted that the Noto quake exposed gaps in Japan’s response systems, with road collapses isolating the worst-affected communities and many displaced residents still homeless months later.

And, they said, the obstacles in Noto show the risk of focusing too much on the Nankai Trough when other parts of the country are equally threatened.

For example, Sugimoto previously worked in Fukuoka, on the southwestern island of Kyushu. The area where she lived has experienced devastating earthquakes in the past, although it is not labeled as one of the high-risk areas near the Nankai Trough.

Because of this, “people didn’t prepare well,” she said. And while the Nankai Trough area received government funding for earthquake preparations, “the Fukuoka area where I lived is not supported by the central government.”

Geller added that while the focus on Nankai has made people in that region well prepared, it is “bad for the rest of the country. Because people think, Nankai is very dangerous, but we are right here in Kumamoto, or on the Noto Peninsula,” he said.

“So this has the effect of lulling everyone into a false sense of security except in the supposedly imminent area.”