By the HalfKey team
Earthquake alert on your phone in Japan: what to do first
The alarm means strong shaking is expected, but it may come only seconds ahead, or after the shaking has started. Here's what the alert leaves out, the sounds worth learning, and a backup if your phone may not receive it.
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When your phone, TV or a building speaker sounds the earthquake alarm and shows 緊急地震速報 (kinkyū jishin sokuhō — Earthquake Early Warning), protect your head and get under a sturdy table, or move away from anything that could fall or topple onto you. Stay there until the shaking stops, and don't run outside.
You may have only a few seconds, so act first and read the message afterwards.
What the alert tells you
The warning means strong shaking is on its way. The Japan Meteorological Agency (JMA) issues it when at least two seismometers have picked up an earthquake and it expects intensity 5-lower (震度5弱, shindo go-jaku) or more somewhere. That's the level on Japan's seismic intensity scale where, JMA says, noticeable damage starts. The warning goes to every area expected to reach intensity 4 or more.
The alert doesn't say how strong the shaking will be where you are, or how many seconds you have. JMA leaves both out on purpose. Its estimate can be one level too high or too low, and each warning area covers roughly a third or a quarter of a prefecture, so the time left varies a lot within it. Treat every alert as strong shaking that could arrive in seconds.
On a docomo Android phone set to English, docomo's guide shows the message as "Strong shaking is expected soon. Stay calm and seek shelter nearby." It says the message follows the phone's language setting.
When the alert and the shaking don't match
JMA explains that the gap between the alert and the strong shaking is a few seconds, or a few tens of seconds at most. Working out where the earthquake is and sending the alert takes a few seconds too. If you're close to where a shallow inland earthquake starts, the strong shaking can reach you before the alert does.
JMA's advice is the same whether the alarm comes first or the shaking does. If you feel strong shaking and your phone is silent, protect yourself anyway.
Because the estimate can also be a level too high, some alerts are followed by only light shaking. When that happens, JMA publishes a notice saying a warning was issued but strong shaking wasn't observed.
Learn the two sounds
Phones on Japan's main networks use one shared buzzer for this warning. TV, radio and the outdoor loudspeakers run by your ward (防災行政無線, bōsai gyōsei musen — municipal disaster radio) mostly use a chime made by NHK. JMA suggests learning both so you react to the sound instead of stopping to read. Its action page links to recordings from NHK and each phone company. On some phones, a voice says 地震です (jishin desu — "earthquake") after the buzzer.
The alarms around you won't always agree:
- NHK broadcasts every warning nationwide, JMA says, wherever the warning area is. If the TV chimes but your phone stays quiet, the warning may be for another region.
- au notes that phones and broadcasts get the warning through different systems, so they can sound at slightly different times. It adds that an au phone can get an alert that a phone on another network nearby doesn't.
In the apartment, in those seconds
JMA's advice for people at home, and docomo's English version of it, add these points:
- Move away from shelves, cabinets and other heavy things that could fall or topple.
- Leave the stove alone. JMA says not to force yourself to put out a flame.
- If you're right beside the front door, docomo's guide says to open it so you keep a way out.
- If you're in a lift, stop it at the nearest floor and get out at once. Docomo's guide also says not to use lifts.
JMA points out that if an alert wakes you, you may not have time to move, which is why it suggests knowing the safe spot in each room in advance. The earthquake preparation guide covers clearing the space around your bed and your route to the door.
On a high floor
Since February 2023, JMA has also issued the warning when it expects strong 長周期地震動 (chō-shūki jishindō — long-period ground motion). JMA describes this as slow, large swaying from a big earthquake. Tall buildings can sway hard for a long time, and upper floors usually move more than lower ones. JMA added it to the warning because more people are now in high-rise buildings.
Its example is the 2011 Tōhoku earthquake. Osaka City measured intensity 3 at most, yet in its high-rise buildings lifts stopped with people trapped inside, and interior fittings and fire doors were damaged. On an upper floor, an alert can mean strong swaying even when the shaking at street level is moderate.
Making sure your phone gets the alert
Japanese mobile networks send the warning as a 緊急速報メール (kinkyū sokuhō mēru — emergency alert message) to phones in the warning area. JMA lists five companies that do this: NTT docomo, au, SoftBank, Y!mobile and Rakuten Mobile. Docomo and SoftBank say the message is free and isn't held up when the network is busy.
A few settings can stop it sounding. au says its phones need the alert setting switched on, that some models stay silent if the text-message volume is off, and that silent mode works differently from model to model. SoftBank says a phone can't receive the alert during a call or without signal. If you have a Japanese SIM, find the emergency alert setting on your phone and switch it on.
If your phone uses a plan from abroad, the Japanese phone companies' pages don't say whether it will receive the alert. So install a second source. The Japan Tourism Agency's Safety tips app pushes Earthquake Early Warnings, tsunami warnings and other weather warnings in English and 14 other languages. It also has a flowchart of what to do next. Allow its notifications when you install it.
Other warnings on the same channel
The same emergency message service carries other warnings, as Rakuten Mobile's page lists. Once you're safe, check which one you received:
| Look for | What it is | What to do |
|---|---|---|
| 緊急地震速報 | Earthquake Early Warning | Protect yourself now, as above |
| 津波警報 (tsunami keihō) | Tsunami warning | The Japan Tourism Agency says to move to higher ground and stay there until the warning is lifted |
| 国民保護に関する情報 (kokumin hogo ni kansuru jōhō) or a missile warning | Government civil-protection alert | Indoors, the Cabinet Secretariat says to move away from windows or into a room without windows |
When the shaking stops
Docomo's guide says this is the time to turn off any flame that's still burning. Then check your surroundings before you move around. The earthquake preparation guide covers deciding whether to stay in the apartment, and the apartment emergencies guide has the numbers to call and what to do if you smell gas.