Japan Earthquake Today

Where to check a Japan earthquake today

The Japan Meteorological Agency is the official source for earthquakes in and around Japan. Within minutes of a felt earthquake it publishes the location, depth, JMA magnitude and the intensity observed across the country, and broadcasters and apps relay it. If JMA or your local government issues a warning or evacuation order, follow it. It takes precedence over any website, including this one.

For international context, the U.S. Geological Survey (USGS) and the European-Mediterranean Seismological Centre (EMSC) also locate significant earthquakes in Japan. You can see USGS-reported events on the EQRadar live map of Japan, look back through earlier events in the history view and check official Pacific tsunami messages on the tsunami page.

1. Japan Meteorological Agency (JMA): official reports, intensities, Earthquake Early Warnings and tsunami warnings for Japan.
2. USGS: worldwide catalog, moment magnitude, and for larger events a ShakeMap and other products.
3. EMSC: fast international reports, including felt reports sent in by the public.
4. EQRadar: a map and timeline of USGS data, useful for seeing where an event sits among recent activity.

How to read a Japanese earthquake report

The number Japanese news shows most prominently is often the shindo, the JMA seismic Intensity. It measures how strongly the ground shook at a particular place, not the size of the earthquake. The scale has ten levels: 0, 1, 2, 3, 4, 5-lower, 5-upper, 6-lower, 6-upper and 7. One earthquake therefore has one magnitude but many shindo values, highest near the source and lower farther away.

The Magnitude JMA publishes first is its own JMA magnitude, while USGS usually reports moment magnitude. The two are calculated differently, so the numbers may not match exactly, and both can be revised in the first hour as more data arrive.

Times matter too. Japan Standard Time is UTC+9, while USGS and EMSC list times in UTC. An earthquake at 02:00 UTC happened at 11:00 in Tokyo. Depth is worth checking as well: Japan has many deep earthquakes inside the sinking Pacific plate, and a deep event of a given magnitude usually causes gentler, more widespread shaking than a shallow one. Our lesson on magnitude vs intensity explains the difference in more detail.

Why Japan has so many earthquakes

Japan sits where four tectonic plates meet. The Pacific plate dives westward beneath northern Japan along the Japan Trench, and the Philippine Sea plate sinks beneath southwestern Japan along the Nankai Trough and the Sagami Trough near Tokyo. This Subduction produces great offshore earthquakes on the plate boundary, deeper earthquakes within the sinking plates, and stress that breaks crustal faults on land.

Inland faults are a separate hazard. They produce fewer large earthquakes than the trenches, but because they can lie directly beneath cities, even a magnitude 6 or 7 can be very destructive. The 3D depth explorer is a good way to see the sloping band of deeper earthquakes that traces the subducting Pacific plate under Japan.

Notable earthquakes in Japan

Japan's modern safety systems were shaped by a series of disasters. The table lists a few well-known examples with approximate magnitudes. The 2011 earthquake and tsunami is covered in depth in our article on the 2011 Japan earthquake and tsunami.

Japan's early warnings and tsunami warnings

JMA operates a nationwide Earthquake Early Warning system. It detects the first, faster P waves and sends an alert to TV, radio and mobile phones when strong shaking is expected. It cannot predict earthquakes; it gives seconds of notice, and people very close to the Epicentre may get little or none. When you hear the alert, protect yourself right away.

For coastal areas, JMA issues tsunami information in tiers: a Major Tsunami Warning, a Tsunami Warning and a Tsunami Advisory. If you are on the coast and feel strong or long shaking, move to high ground or an evacuation building immediately, without waiting for a warning. A Tsunami can arrive within minutes, and later waves can be larger than the first.

If you felt an earthquake in Japan

During shaking, Drop, Cover and Hold On, and stay away from windows and heavy furniture. Do not rush outside, where falling glass and signs are dangerous. Once it stops, check for injuries and fire hazards, then check JMA for the intensity in your area and any tsunami information. Expect aftershocks, and after a strong event watch for landslides in hilly areas. Your city or town will announce shelters and evacuation orders.

Frequently asked questions