What to know and how to stay safe in Japan

On March 11, 2011, an earthquake measuring 9.0 on the Richter scale triggered a huge tsunami, which hit the northeastern Pacific coast of Japan one after another. An estimated 19,729 people died during the disaster, most of which were caused by these waves. More than a decade later, more than 2,500 people are still considered missing, and just recently, a little girl’s body fell into the sea that same day. retrieved.

This was not the first tsunami to hit Japan, nor would it be the last. In recent years, the coast of the Sea of ​​Japan has experienced tsunamis, 2024 Noto Earthquake,and 2025 Kamchatka Earthquake This resulted in tsunami warnings of varying levels being issued for the entire coast of Japan. For anyone living in or visiting coastal areas of Japan, the risk of tsunami is something to consider: If you hear a tsunami warning or advisory, or feel a large earthquake while near the coast, do you know what to do or where to go?

November is a prime month for tsunami preparedness practices (November 5th is world tsunami awareness day), let’s take this opportunity—or any day—to explore tsunamis: what they are, why they’re so dangerous, and how to stay safe.

Tsunami evacuation route signs. Photography: DimiTalen, CC0 (

Tsunamis: what they are and the risks they pose

exist World Risk Index 2025Japan ranks third in the “exposure” indicator. This means that, out of 193 countries, it is the third most likely to experience “extreme natural events and the negative impacts of climate change.” A solid government, coupled with social stability and strong emergency relief preparedness, helped its overall “risk” index rise to 17th place, but this does not negate the need for personal emergency preparedness for natural disasters, whether they are floods, landslides, tornadoes, earthquakes, typhoons or tsunamis.

According to the United NationsAlthough rare, tsunamis cause more deaths than all other natural disasters. Over the past 100 years, 58 tsunamis have occurred, killing more than 260,000 people, with an average of 4,600 deaths per tsunami. These fast-moving, destructive waves are caused by a variety of phenomena, including landslides, volcanic eruptions, and, most commonly, earthquakes, which are responsible for more than 70 percent of tsunamis. Japan is a hotspot for seismic activity, so it’s no surprise that the country experiences more tsunamis than any other country on Earth.

Because the phenomenon that causes a tsunami displaces large amounts of ocean water in an instant, the resulting waves are extremely powerful. Unlike normal wind-driven waves, the entire body of water is affected, from the seafloor to the surface.

In a tsunami wave train (the name for the multiple waves that make up a tsunami), the waves are inconsistently spaced and of varying height; the largest waves may not reach the coast first and, in fact, may take several hours to arrive. Meanwhile, the intervals between waves can vary from minutes to hours. From the first tsunami to the last tsunami can last more than a day.

Screenshot of 2025 Kamchatka earthquake and tsunami warning. Source: Japan Meteorological Agency via Wikimedia Commons, CC BY 4.0 (

The waves produced by tsunamis are also much faster than ordinary waves. The propagation speed of wind waves is about 8 to 100 kilometers per hour, while the propagation speed of tsunami waves can reach 800 to 1,000 kilometers per hour in deep water and 30 to 50 kilometers per hour in shallow water. At this speed and with this amount of water, the impact of a tsunami wave is much greater. According to the National Oceanic and Atmospheric Administrationjust 15 centimeters of fast-moving water can knock down an adult.

The danger doesn’t end at landfall, either: a tsunami’s retreat can be even more dangerous than its arrival, because any vehicles, buildings or debris caught in the waves as they hit will be dragged back out to sea, potentially colliding with people trying to stay afloat and escape safely.

Part of the Japan Earthquake and Tsunami Monitoring System. Excerpted from images used in “Earthquakes and Tsunamis: Observation and Disaster Mitigation” (Japan Meteorological Agency) (

Early warning systems and alerts

Although tsunamis are extremely dangerous, thanks to science and international cooperation, their arrival is generally no longer a surprise. At least for earthquake-related tsunamis, the seismic and water-level network provides scientists with data they can use to predict whether a tsunami will occur.

For tsunamis caused by other phenomena, such as underwater volcanic eruptions, the situation is not so simple. But across the ocean, gauges, instruments and buoys constantly monitor the ocean.

Since the 2004 Indian Ocean tsunami, cross-border cooperation has meant that information about tsunami dangers can be shared quickly and widely. So even if an earthquake occurs, such as one off the coast of Chile, tsunami information will spread around the world. Just minutes to 2025 Kamchatka Peninsula earthquake, Tsunami warnings and coastal warnings are in effect across the Pacific, from Japan and the Pacific Islands to countries along the west coast of North and South America.

Tsunami buoys used by the U.S. DART (Deep Ocean Tsunami Assessment and Reporting) network. Photo by Chris Boyer on Unsplash

In Japan, various alerts are shared via: J-alerta satellite-based emergency broadcast system that instantly sends warnings to city speakers, TVs, radios, registered email addresses, apps and mobile phones. Foreign phones can also receive alerts, but will need to be used with a SIM card or eSIM from a supported carrier and emergency alerts will need to be enabled.

For phones that do not meet these requirements, a variety of apps are available that provide warnings and valuable information about safety and evacuation, e.g. Neurodisaster preventionYurekuru call (app store | Google Play) or Safety tipsan application recommended by the Japan Tourism Agency.

Japan’s public broadcaster NHK provides alerts from the following countries Japan Meteorological Agency (JMA) through its NHK World Japan App. NHK also offers a number of on-demand programs that share important disaster preparedness information, including Responding to Disasters.

“To future generations: If an earthquake occurs, please evacuate to a higher place than here.” Tsunami height mark in Minamisanriku City, Miyagi Prefecture. Photo by Mizushimasea, CC BY-SA 4.0 (

If you’re traveling without a data or service plan (or pocket Wi-Fi) when a disaster strikes, connect to apps and websites that spread emergency information. 50 japanIt is a free public wireless LAN service provided by major Japanese carriers in emergencies.

There’s no need to enter a password or create an account, meaning instant access. However, to access Five Zero Japan, you need to be near a mobile operator Wi-Fi access point — think convenience storecafes, restaurants, shops, etc.

Unfortunately, some tsunamis occur too close to land for warning systems to release information in a timely manner. Therefore, it is important to understand natural tsunami warning signs, such as strong or prolonged earthquakes. You may also hear a loud roar in the ocean or notice the ocean acting strangely; a sudden high or low tide is a sign of heading for higher ground.

Stay safe on the ground

Emergency alerts, whether coming from your phone or the city’s speakers, will tell you what to do next, whether that’s evacuating water and coastal areas for tsunami warnings, or evacuating to higher (and higher) ground when tsunami warnings and major warnings are received. Keep in mind that since a tsunami is a series of waves, the safe high ground you initially find may be overwhelmed by subsequent waves.

Just as the seaside is dangerous, so are rivers and streams, which are the highways for seawater to flow inland. During the Tohoku earthquake, tsunamis flooded rivers and then penetrated 10 kilometers inland.

To help guide your escape, Japan’s seaside towns provide basic elevation information and directions to emergency evacuation sites, which you can find on roads, posts and information signs. It doesn’t hurt to be aware of these as well as any elevated or high-rise buildings designated as tsunami evacuation structures as you explore.

Some cities, e.g. Kamakura In Kanagawa Prefecture, available Disaster prevention information tailored for touristswhile some other countries provide general disaster preparedness resources for residents, e.g. Tokyo Disaster Prevention Manualwhich includes details for various scenarios.

Don’t wait until a disaster strikes to review the information provided; if you know you’ll be spending time in a coastal area, see what information you can find before arriving. Fortunately, your newfound knowledge will still be academic—but if the worst happens, you’ll be better prepared to survive whatever difficulty nature throws at you.

Consular Registration and Your Emergency Preparedness Checklist

In the event of a major natural disaster, it is important that your country’s government knows where you are. Many countries offer registration services for citizens traveling abroad, such as the United States Smart Traveler Enrollment Program or canadian Registration of Canadians Abroad

Registering your travel information not only allows your government to provide you with emergency information for your destination, it also helps consular services understand how many citizens may need support and how to contact them.

Of course, general travel advice and rules apply. Always carry your passport with you when traveling. Have your embassy or consulate contact information ready and keep family and friends informed of your travel plans. Also, make sure you have small change or bills to use at vending machines, and buy a phone charger.

Most importantly, follow all instructions provided by local officials, evacuation zone or shelter staff, and volunteers. With everyone’s cooperation, they will be better able to put Japan’s well-thought-out protocols into practice, saving lives and making a difficult experience more bearable.

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Updated on December 2, 2025