Tsunamis in Japan: Why They Happen & What To Do

Published December 4th, 2020

I come from Singapore — it’s so peaceful and quiet when it comes to natural disasters. Boy, was I in for a treat when I moved to Japan, where these dramatic forces of nature are the norm. Here, there are days where the people in it are overwhelmed by feelings of fear and distress instead of exhilaration and euphoria. The ones that bring those emotions out are frequent natural disasters including tsunamis, disrupting daily lives and even tragically take some away. Japan is not randomly chosen nor volunteered to be acquainted with these sizeable waves. There’s something that makes this island nation different from others to be on the recurring receiving end of such natural forces. In this article, we’ll look at Japan’s tragic relationship with tsunamis, why tsunamis are so frequent in Japan, and what to do when you’re at risk of a tsunami strike — regardless of whether you’re in Japan or not.

Japan’s Tsunami History

Source: yisris from Flickr

Japan and tsunami aren’t new to each other — they have quite a history, unfortunately. Since 684, there have been a total of 141 waves that are classified as a tsunami — with a total of about 130,000 deaths total. Back in 1741 was the strongest tsunami ever recorded. This huge wave was caused by a volcano north of Hokkaido Island with a magnitude of 6.9, reaching a height of 90 meters and taking 1,607 lives along with it. While it may be the biggest one, it wasn’t the one that took the most number of lives — that’s the one in 1498 with an earthquake of 8.3 magnitudes that caused a tsunami of 10 meters and killed 31,201 people. Even with those two, the one that really affected Japan was the tsunami in 2011, where agriculture, development and the economy were seriously damaged. On March 11 of that year, an earthquake of 9.1 magnitudes unleashed a tsunami of 55 meters tall in Japan. Can you imagine how big this tsunami must have been to reach 11 further countries! There was a total of 15,894 deaths in Japan and thousands more in other countries. The damages the tsunami caused added up to USD$235 billion, the costliest natural disaster in world history!

Reasons Why Japan Have Frequent Tsunamis

Do you know what people say about being in the right place at the right time? Well, Japan is located in the wrong place...all the time. This island nation is along the “Pacific Ring of Fire”, which is an imaginary horseshoe-shaped zone that is on the rim of the Pacific Ocean. On this ring, you’ll get the most activity for earthquakes and volcano eruptions. To make matters worse, Japan is smacked on top of four shifting pieces of Earth’s crust known as the tectonic plates that mash and collide. Because of these two factors, Japan has about 1,500 earthquakes every year even though some of them don’t go any bigger than 3.9 magnitudes.

How Are Tsunamis Created?

So how exactly are tsunamis created? These huge, tall waves need some serious energy to be so big. Normal waves are formed when energy passes through the water, and that causes it to move in a circular motion. One way waves are formed is by the wind when there’s friction on the surface of the water and causing a continual disturbance, resulting in surface waves. Another type is the tidal wave that is made by the gravitational forces of the sun, moon and earth. Tsunami waves are not formed by surface or tidal waves — they are created when there are huge disruptions, including but not limited to earthquakes, volcanic eruptions and landslides that occur under the sea. When this happens, large volumes of water move together at full depth at a speed you didn’t think water could. The water then absorbs the energy of these disturbances, then they travel inland with the constantly piled of large volumes of water. By the time it reaches the shore, can you imagine how big the waves can be? The drawback, referring to the water from the shoreline receding, is one of the warning signs that a tsunami is approaching the shoreline. Just because it’s a warning doesn’t mean you have a lot of time — it can be a few seconds to a few minutes before the full tsunami moves inshore.

Tsunami Warning Categories in Japan

Because Japan is so prone to tsunamis, they have set up measures in case one does happen. There are three warning categories that are exclusively for a tsunami, and each one has actions to take based on the height of the tsunami. The first category is the Tsunami Advisory, where the tsunami is expected to be up to only 1 meter in height. When this warning is issued, anyone who is exposed offshore may be caught in strong currents into the sea. Fish farming facilities as well as small vessels like boats may be washed away or capsized. The second category is the Tsunami Warning, with the expected height of 1 meter to 3 meters of the tsunami. The tsunami waves for this kind are expected to hit hard, so low-lying areas will be damaged and buildings will be flooded. People are advised to evacuate the coastal as well as river areas to higher ground or a tsunami evacuation buildings — those who are exposed will be caught in the strong currents. The third and last category is for tsunami waves over the height of 3 meters: Major Tsunami Warning. This warning is for a type of tsunami that is expected to completely destroy wooden structures, deeming it to be extremely strong. Similarly, people are strongly advised to evacuate coastal areas as well as river areas to higher ground or a tsunami evacuation building. Even though there are tsunami warning systems, they might not be issued early enough for evacuation — especially when it’s the Major Tsunami Warning since this is when the wave of the tsunami comes at extreme speeds inland.

What To Do If A Tsunami Strikes

Source: RachelH_from Flickr

Some of us may be lucky enough to be living in a country where tsunamis never happen — some others are not. Whether you’re living in a country prone to tsunamis or even just traveling to Japan, it’s best to know what to do if one does strike.

Do not panic

First and foremost: don’t panic. When we’re overwhelmed with such emotions, we won’t be thinking straight and end up making rash decisions. Keep calm and recall the procedures to take for a tsunami strike. Keep in mind that tsunami waves can crash inland at unexpected times — even if you see it far out the sea, chances are they’re moving really fast. I know your first instinct is to take your belongings with you, but don’t panic pack — your life is the most precious thing, so leave as soon as you can!

Higher, not further

Our instincts would want us to go further, but instead of doing that, go higher up. Tsunami waves can reach heights of more than 10 meters and tsunami evacuation sites, usually not that high up either, can be dangerous places to be in this situation. If you are seeking refuge at the evacuation site, that is still okay too. They’re made especially for that reason: to be a safe place in times like these. When you are at one, do not leave the site. A tsunami is not just one single wave but a series of them. The intervals between them can be seconds or even hours apart, so wait it out until the tsunami warnings are fully completed.

Rivers are threats, too

Don’t think that just because you're not by the ocean, you’re safe. Rivers and other coastal areas are at risk too — floods are highly to happen as the waves can travel up to smaller streams. Seek refuge at higher ground or a tsunami evacuation site.


While it’s unfortunate that Japan has the highest threats for a tsunami, it’s unchangeable. What we can change is how we react to it to save our lives and the lives of others. Don’t let the proneness to natural disasters in Japan scare you off from visiting (or even living) in the country — this island nation is beautiful and peaceful, with tons of measures prepared and precautions taken to combat these natural disasters.