The Next Big Earthquake in Japan: Are You Prepared?

Navigating earthquakes is a tricky part of living in Japan. In the average year, Japanese people are shaken around 1,500 times. While most of these are minor shakes, experts say Japan is due for a megaquake—the next big earthquake in Japan that could cause widespread destruction. 

Recently, the Nankai Trough has been in the news as a potential megaquake that could hit even the big cities. Making sure you’re prepared by natural disaster vocabulary and preparing for an earthquake has perhaps never been as important as now.

Is a Megaquake Going To Hit Japan?

Predicting whether we are due for a big earthquake is tricky because there are so many factors involved. The Nankai Trough is the butterfly effect writ large: the smallest changes can have huge repercussions.  

Japan, of course, has a long history with big earthquakes. Most adults in Japan will be familiar with at least one sizable earthquake and their devastating effects:

Thankfully, the megaquakes (those with a magnitude over 8) occur only every 100 to 150 years. The bad news is that the Tokai area hasn’t had a quake for 158 years, leading some to worry that we are overdue. 

This is concerning because the fault line responsible for Tokai earthquakes is also connected to the Nankai and Tonankai earthquake-prone regions. Historically, when one earthquake occurs—such as the Ansei-Tokai earthquake in 1854—it is often followed soon after by another, like the Ansei-Nankai earthquake, which struck the very next day. 

While these patterns are intriguing, Professor Takeshi Sagiya from Nagoya University’s Disaster Mitigation Research Center warns against assuming a mega-earthquake is imminent: 

“Most so-called ‘predictions’ today are not true predictions,” Sagiya explains. “Among earthquake scientists, it is widely understood that completely accurate earthquake forecasting is impossible. While some major earthquakes are preceded by smaller ones known as ‘foreshocks,’ we usually recognize them as such only in hindsight—after the main earthquake has already occurred.”

What Would The Impact Be?

Japan’s Earthquake Research Committee has raised the estimated probability of a Nankai Trough mega-earthquake occurring within the next 30 years. Previously listed as “70 to 80 percent,” the likelihood is now at a solid 80 percent. The committee, which updates these probabilities annually, explains that the risk rises as more time passes since the last major event.

This massive quake, expected to reach a magnitude of 8 to 9, could have devastating consequences:

• Tsunami waves up to 30 meters high, threatening coastal areas.
• A death toll of up to 230,000 people based on government projections.
• Over 2 million buildings destroyed or burned due to fires and structural damage.
• Severe disruption to Japan’s industrial heartland, including major economic centers.

The Disaster Mitigation Center also presents a simulation of how a massive earthquake would impact Nagoya—a city not considered one of the most at-risk areas. Even so, a Nankai Trough earthquake would light up half the map in red, particularly in the west.

While this represents a worst-case scenario, that scenario is truly devastating:

• Economic impact: An estimated $1.45 trillion in damages—a third of Japan’s GDP.
• Death toll: Up to 323,000 people.
• Tsunami waves: Reaching 30 meters high in coastal areas.
• Widespread destruction: Severe damage to Shizuoka, Wakayama, Kochi and Miyazaki prefectures.

How Worried Should You Really Be?

Professor Nishimura Takuya of Kyoto University’s Disaster Prevention Research Institute urges people not to panic but to prepare. “The increasing probability doesn’t mean an earthquake is imminent—it’s just a reflection of the passage of time,” he says. While some alternative calculations estimate the risk at 20 to 40 percent, the consensus remains that a Nankai Trough quake is highly likely.

Moreover, Hiroshi Goto of Kyoto University’s Disaster Prevention Research Institute believes that it is better to be prepared than afraid, especially for those in the big cities. 

“I think the big cities far from the Pacific Ocean, such as Osaka and Kyoto, would not be affected by severe structural damage,” he said. “Although there would be power outages and road closures, in fact, the big cities would likely be essential in supporting the severely affected areas, mostly on the Pacific Coast.”

Dangers During and After a Major Earthquake in Japan         

Being prepared is the most important thing for earthquakes. However, all of them would be risks in a megaquake, and only a few factors cause the most fatalities. 

The biggest dangers are:

• Building collapse: Weak or old structures are at the highest risk of failure, especially in high-magnitude quakes.
• Tsunamis and ‘drawback’ waves: Coastal areas face a major threat from powerful tsunami waves and the rapid recession of water before they hit.
• Falling objects and debris: This includes collapsing walls, fences, vending machines, furniture and signage.
• Fire: Gas leaks, electrical sparks and overturned stoves often lead to widespread fires after major earthquakes.
• Landslides and ground liquefaction: In mountainous or unstable areas, landslides can bury homes and roads, while liquefaction can cause buildings to sink or tilt.

Moreover, hazards that complicate disaster response are:

• Blackouts: Power outages can last days or weeks, affecting everything from hospitals to communication.
• Cellphone and landline failures: Cable damage and base station failures can make it difficult to contact emergency services or loved ones.
• Disrupted essential services: Infrastructure damage may make hospitals, emergency responders and fire departments unable to operate.
• Water and sewage system failures: Broken pipes can lead to shortages of drinking water and sanitation issues, increasing disease risk.
• Transportation shutdowns: Roads, bridges and rail networks may be inaccessible due to structural damage or debris

Earthquake Preparedness and Survival Tips

Even before a major earthquake strikes, taking the right precautions can make all the difference. Here are key actions to prepare:

Earthquake Preparation

• Find your nearest evacuation site: Locate designated emergency shelters, such as those in Tokyo or Osaka and emergency food stock shelters.
• Prepare a survival kit: Keep it stocked with essentials (food, water, flashlight, first aid) and store it somewhere easily accessible.
• Participate in drills: Join local earthquake drills, like those held in Tokyo, to practice emergency responses.
• Download Japan’s official disaster guide: A comprehensive resource for natural disasters.
• Know your embassy’s location: Foreign residents and visitors should be aware of their embassy’s emergency contact information.
• Sign up for J-Alert: The Japanese government’s earthquake and disaster warning app.
• Secure large furniture and electronics: Use anti-tip straps for shelves, TVs and cabinets to prevent falling hazards.
• Create a clear evacuation route: Ensure there’s a clutter-free path from all beds to the nearest exit.
• Apply anti-scattering film on windows: Prevents shattered glass from becoming a hazard during strong tremors.

Immediate Survival Actions

• Protect your head and body: If no cover is available, wear a helmet or use a sturdy table or your hands for cover
• Avoid fire hazards: Stay away from stoves, heaters and gas sources. If safe, turn them off immediately.
• Open a door or window: This can prevent entrapment, as door frames may warp, blocking escape routes.
• Wear protective footwear: Solid-soled shoes help prevent injuries from broken glass and debris.
• Avoid elevators: Use stairs instead, as elevators can become trapped between floors.
• Stay updated: Use emergency hotlines such as NTT’s Disaster Emergency Message Dial (171) service or Docomo’s push-button service and All Areas Disaster and Evacuation Information. 

Summary

Earthquakes are terrifying. As part of writing this article, I rode a device at Nagoya University that simulated a megaquake. It was so intense that I had to hold onto special handrails to prevent myself from falling over. 

Afterward, I still felt rattled even long after the shaking had stopped. It made me realize that it is difficult to think straight after a megaquake. The key thing is to make sure that you have everything prepared so that your immediate response will be a safe one.

What are your experiences with earthquakes? What advice is useful for you? Anything else you think other people should know about the next big earthquake in Japan? Let us know in the comments.

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