Off the southern coast of Japan, from Shizuoka to Kyushu, there is a massive ocean-floor trench. Along this trench, the Philippine Sea Plate is sinking beneath the Eurasian Plate. As the two plates grind against one another, friction builds and builds … and builds.

Friction has been accumulating at this unfortunate meeting point, known as the Nankai Trough, for 75 years. History has recorded nine major Nankai Trough earthquakes, over the course of more than a millennium. These are no ordinary shakes, either, and a quake there could directly affect well over a third of Japan’s population, from Kagoshima to Yokohama.

“When the Nankai earthquake occurs, it will be a huge historical event for Japan,” says Nobuo Fukuwa, a professor at the Disaster Mitigation Research Center at Nagoya University. “On par with when World War II ended or the 1854 earthquakes that helped lead to the end of the Edo Period. It will shake half of Japan.”

Since the year 1361, Nankai Trough earthquakes have struck approximately every 90 to 150 years, but scientists believe that an earlier scenario is possible.

But, what if it struck now?

Yes, right now. What if the plates slip and all that tension releases? What would you do?

The moment

You’re at home in Nagoya when you feel the room start to shake. The last two Nankai Trough earthquakes were magnitude 8 or higher, with shaking reaching Level 7 on the Japanese Seismic Intensity Scale. This one is around that level, too.

Some of the dozens of seismometers placed along the coasts of Kyushu, Shikoku, Wakayama and Shizuoka pick up the movement and instantly transmit an early earthquake warning. Trains and industry machinery are shut down. Alerts are broadcast all over Japan, but they don’t arrive before the first tremors hit the coast.

Level 7 shaking.

You’re thrown off balance, completely unable to move. Most heavy and unanchored furniture slides. Trees topple, bridges collapse, windows shatter and concrete crumbles. Even earthquake-resistant residential buildings start to collapse in the violent shaking. In the mountains, landslides erupt. It feels like it lasts forever, the relentless jolting, jerking, swaying.

In the worst-case scenario, there is truly nothing you can do. The earthquake is too powerful.

But if you’re not so unlucky to be close to the epicenter, you can move. Barely. It’s terrifying: it feels like a factory is exploding, like a plane is crashing. Your mind is screaming: fight or flight.

So what do you do?

A) Escape?        B) Stay put?

Fleeing will send you straight into the line of fire of breaking glass and toppling furniture. Always choose B: Shelter yourself from falling objects, cover your head with a blanket, a bookbag — anything — and wait for the tremors to subside.

If you’re in the living room or kitchen, get down under a table. In your bedroom, put a quilt and pillow over your body. In the classroom, take cover under a desk. In the train, crouch down and grab a rail; in the station, move to the nearest column, crouch, and hold on. If you’re driving, move to the side of the road and stop. Wherever you are, cover your head and get low.

The initial damage is done: trees have fallen, furniture is everywhere. Older homes and even some apartment buildings have collapsed. Many newer buildings have cracks in the walls and shattered windows. Infrastructure for gas, water and electricity are all severely disrupted. The ground is cracked. There have been car accidents, fires have started due to toppled electricity poles. The world is panicking, and the only thing on your mind is your family, your loved ones. All you can think is: Are they OK? Are they OK?

So what do you do?

A) Escape?     B) Call your family?

Now you choose A. If you don’t save yourself, you won’t be able to help others. And this choice is all the more urgent if a tsunami is approaching.

Secure an exit while checking for fire hazards, staying well clear of glass and walls. Put on slippers or shoes as soon as you can and move toward the exit. Think twice before going to the ground floor of an old structure, as the building may collapse on you. Use fire escapes if necessary. If you’re trapped, don’t move suddenly, but shout for help. In high-rises or malls listen to the public address system for instructions. Once outside, move to an open area without falling hazards, like a park.

Once you have temporarily secured your surroundings, gather information to decide whether or not you need to evacuate. Contact and check on your loved ones and neighbors. Use a radio, TV or smartphone to get updated information from the authorities. A decision about whether or not to evacuate could be a matter of life or death — luckily, you packed an emergency go bag in advance that has everything you need.

While you should help any neighbors or people in need on your way, experts emphasize the importance of saving yourself.

“One lesson learned from the Tohoku disaster is to not think about others, just escape,” says Kaori Kitagawa, an associate professor at University College London who studies disaster prevention education. “This isn’t necessarily to be selfish. It’s based on trust. If you could trust that your family, friends and colleagues will escape, that means that you can escape, too. Evacuation delays occur because people think about others. But if everyone was responsible for their own lives, you can save yourself.”

Start early: Kindergarten students take part in an earthquake drill in Amagasaki, Hyogo Prefecture. The area is expected to be hit hard when a Nankai Trough mega-quake occurs. | KYODO
Start early: Kindergarten students take part in an earthquake drill in Amagasaki, Hyogo Prefecture. The area is expected to be hit hard when a Nankai Trough mega-quake occurs. | KYODO

A dominant show of force

The “Big One” has struck. And that means the water is rising.

“Tsunamis are not as majestic as Hollywood likes to depict,” says Matt Ketchum, who experienced the 2011 Tohoku earthquake and tsunami firsthand and wrote about it for this page a week ago. “(They’re not) a deep blue sprinkled with white flecks of foam, (they’re) muddy black, polluted with the remnants of … dirt, rocks, trees, homes. Until then, I had never seen such a dominant show of force by my natural surroundings.”

If you’re near a river or the coast, don’t wait for any sort of announcement. Get going. Get out of your car if you’re driving. If you know the evacuation route, follow it. If not, get uphill or to a tall, sturdy building.

There is no timeline. You could have anywhere from just 10 minutes to an hour or two before the waves hit. Pay attention to any warnings or information that have been issued online, on TV or over the radio.

If you make it up in time, you will witness that black wall of death rise out of the ocean like a monster, long sealed-away: a frothing soup of cars, timber, garbage, rocks and debris rushing toward you. Wooden houses are completely swept away.

Rescue operations are dispatched almost immediately, although the water level will take hours and hours to recede. From your high-point, whether it is a rooftop, temple or city park, you will wait with others, over the ruins of a civilization.

Regardless of the threat of a tsunami, an evacuation order may be issued for your area. If you are still in your home, put out any fires, turn off the circuit breakers, close off the main gas valve, grab your go bag or the absolute essentials — food, water, map, phone battery, blanket, important documents — and leave a memo on the door confirming your safety and where you are going.

Your life for the first few minutes of an earthquake as well as the next few hours, days and weeks revolve around how well you prepared in advance. And did you?

High ground: An evacuation tower in Kuroshiro, Kochi Prefecture, hopes to offer some refuge in the event of a tsunami. | KYODO
High ground: An evacuation tower in Kuroshiro, Kochi Prefecture, hopes to offer some refuge in the event of a tsunami. | KYODO

Essential preparations

While certain infrastructure and technological protections from earthquakes and tsunamis in Japan have improved since March 2011, individual and community preparation remain key. Here are the bare essentials:

  1. Prepare an emergency go bag with: Flashlight, helmet, gloves, food, batteries, lighter, candles, water, blanket, clothing, first-aid kit, and your passport/ID/health insurance card/seal and a family photograph all kept together in a sealed plastic case.
  2. Keep an extra stock of essentials (water bottles, food, toilet paper, plastic bags, disinfecting wipes, etc.) in your home in addition to emergency supplies in case of loss of electricity, gas and water: a portable gas cooking stove, medicine, emergency toilet, spare cell phone batteries and a hand-rechargeable radio.
  3. Secure furniture to the walls and floors with L-brackets, tension rods or casters/anti-slip pads and keep an area of your home clear.
  4. Confirm the hazard map and evacuation route for your neighborhood and identify nearby large parks and community facilities.
  5. Install seismic retrofitting for homes and buildings constructed before 1981.

The first four are simple steps that you can arrange in a single weekend of errands. Losing a day or two for greatly increased emergency preparedness is a worthwhile exchange.

The other key part of disaster preparedness happens not at the individual, but at the community level.

“The disaster research community emphasizes that experts can’t deal with this alone,” says Kitagawa. “Community members need to have agency, control and genuine interest in making changes.”

As a good example, Kitagawa points to a community farm in Sendai that grows fruits and vegetables to be used in case of a disaster. The farm has also served as a way for the community to bond and create a trusting relationship.

“That is essential for wanting to help each other,” says Kitagawa. “If a disaster hits, the first call of help is neighbors. It could be a while before first responders arrive. If you don’t know or like each other, it’s very difficult to develop that kind of relationship.”

Here are key steps to take for community preparation:

  1. Know your neighbors and greet them regularly.
  2. Hold a family meeting. Decide on an evacuation area and evacuation route, and designate a meeting place and method to confirm each other’s safety.
  3. Participate in local disaster drills, and join or create a Citizens Disaster Response Team in your community, neighborhood association or company. These teams can help educate members of your community and stockpile emergency supplies like rope, fire extinguishers, ladders, shovels, etc. — as well as food.

If you’re interested, there is always more to learn. Disaster preparation courses and drills can teach essential skills like first-aid, cardiopulmonary resuscitation and firefighting, plus tips for essentials like warming yourself and preventing dehydration. The Tokyo metropolitan government provides a great guide to pointers like these on its website.

But if you’ve taken the eight basic steps above, you’ll be in much better shape when a large-scale earthquake and/or tsunami does occur.

Practice makes perfect: Municipal officials in Osaka hide under their desks during an emergency drill to prepare for a Nankai Trough mega-quake. | KYODO
Practice makes perfect: Municipal officials in Osaka hide under their desks during an emergency drill to prepare for a Nankai Trough mega-quake. | KYODO

We’ve improved, but not enough

The 2011 earthquake and tsunami surprised and shook the disaster preparedness community in Japan.

“They had prepared everything (in Tohoku),” says Kitagawa. “They had massive levies. But there was a realization that something much bigger can happen.”

As a result, engineers and experts have been hard at work preparing Japan for the next major earthquake. Fukuwa says that the percentage of earthquake-resistant buildings has grown substantially since 2011, and newly constructed tsunami evacuation towers will save lives. According to Shunichi Koshimura, a professor at the International Research Institute of Disaster Science at Tohoku University, new artificial intelligence technologies can create detailed simulations that predict how a disaster event will unfold in real-time.

“We are aiming to be able to predict in real time how big a tsunami will be after an earthquake,” says Koshimura. “Right now we can predict the height, how far inland it will go and its impacts.”

Other newly developed AI can help designate the best evacuation path, identify potential rescue areas, and keep track of which locations have water and supplies for relief.

However, Koshimura says these new technologies don’t change the physical reality of a disaster.

“You still need to be able to flee to a safe place,” he says. “The best thing is to be able to take the fastest and best action yourself without AI.”

Fukuwa, who studies infrastructural preparation for a Nankai Trough earthquake, says that the damage to Japan’s industry and energy infrastructure could be devastating. After a quake, energy and water shortages could cause severe disruptions to supply chains, shutting down all factories and industry.

“We’re continuing to implement a lot of new measures,” says Fukuwa. “We’ve gotten better at protecting lives, but not the infrastructure of society. Even if we save lives, everything will still be swept away.”

Responsibility for preparation lies with everyone. Researchers need to continue to develop new technologies and infrastructure, governments need to implement them, communities and individuals need to prepare, and the media needs to break down the overwhelming amount of information to help people clearly understand what they need to do.

A Nankai Trough earthquake could be a Big One among Big Ones, but preparation doesn’t need to be overwhelming: Emergency bag and extra stock. Evacuation map. Community communication. Take ownership of your own safety and that of your family and community — the rest will come. And you will be ready for the next Big One.

Tadasu Takahashi contributed to this report.

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