Can I use this as an early warning?

No. An early warning is worth having because it arrives seconds before the shaking; this approach cannot — measured at roughly 2 minutes 30 seconds from event to publication. Beyond that, anything that depends on a tab being open and the network being up fails silently. Use broadcast media or an official disaster app built for the purpose.

How often does it refresh?

Every 90 seconds while you are looking at the tab, and not at all while it is hidden — so abandoned tabs do not keep hitting JMA’s servers.

Where does the data come from?

JMA’s published feed and report documents, read directly by your browser. Nothing passes through this site and nothing is altered.

How much data does it use?

About 2KB to check for news and 1–2KB for a report — transfer sizes, measured in August 2026; they rise and fall with seismic activity. Only the optional history is larger, at about 40KB.

I felt it but nothing appeared here.

Three likely reasons. The delay before publication (measured at about 2 minutes 30 seconds). Shaking below intensity 1, which is not reported at all. Or the tab was hidden, which pauses refreshing — returning to it reloads. Failing those, what you felt may not have been an earthquake.

Does it cover earthquakes outside Japan?

Only those with a recorded intensity in Japan, or that could send a tsunami to Japan. This displays what JMA publishes, so distant events with no effect on Japan are absent. To follow worldwide seismicity, the USGS public data is the better source.

How far back does the history go?

As far as the published feed carries — which is not far enough for long-term statistics or historical research. Use the seismic intensity database published by JMA for that. The history loads on demand because it is around 40KB — about twenty times the news feed.

Magnitude versus intensity

Magnitude measures the earthquake — one value per event. Intensity measures shaking at a place and differs across locations.

The sequence of reports

A preliminary intensity report comes first, followed by fuller information with epicentre and magnitude. Measured here: about 2 minutes 30 seconds from the event to the first report.

Levels 5 and 6 are each split in two, a refinement made in 1996. The difference is visible in the damage.

Depth and how it shakes

At the same magnitude, a shallow focus shakes harder directly above and over a smaller area. A deep one does the opposite, and places far from the epicentre can shake more than those near it. That inversion happens because the structure underground carries the energy preferentially in some directions.

What the reports say about tsunami

Each report states whether a tsunami is a concern — often explicitly "no tsunami is expected from this earthquake" — and a separate tsunami forecast may follow. ⚠️ This tool only displays what has been published, so never use it to decide about a tsunami. Near the coast, strong shaking means move to high ground without waiting for any announcement.

JMA now often avoids it in favour of "seismic activity". Calling something an aftershock invites the assumption that it will be smaller, and in practice a larger earthquake can follow the first. Even as the count falls off, expecting more shaking of similar size is closer to how these sequences behave.

Back to all tools／ Weather & alerts

Recent earthquakes (JMA)

This tool fetches directly from the Japan Meteorological Agency (www.data.jma.go.jp / www.jma.go.jp); it does not pass through this site’s server. Auto-refresh runs every 90 seconds only while the tab is visible, and stops when hidden. The history file is about 40KB over the wire (roughly 550KB once decompressed) — about twenty times the news feed — so it loads only when you ask for it.

Shows the latest earthquake report from the Japan Meteorological Agency, refreshing automatically — epicentre, magnitude, maximum intensity and the intensity recorded in each prefecture. Note: these are published records, not alerts.

Latest report

⚠️ This is not an early warning system. Everything shown has already been published — measured at about 2 minutes 30 seconds from event to publication. For evacuation decisions, use broadcast media or official disaster information.

Fetching…

Source: Japan Meteorological Agency. Intensity is measured per station and varies within a prefecture. The JMA publishes this data in Japanese only, so the headline sentence and the epicentre name are shown exactly as issued; prefecture names carry an English reading.

History

Loads the last few months of earthquakes.

These are reports the JMA has already published, not early warnings. It is built for working out what that shake was afterwards, not for opening while the ground is moving.

All tools

Why this one

Intensity per prefecture: It reads JMA’s individual report documents, so you get more than the maximum: which prefecture felt what. The summary list format carries only the maximum.
Waiting costs almost nothing: Checking for news uses a 2KB feed, and only then is a single report document fetched (1–2KB). Auto-refresh runs only while the tab is visible.
Intensity sorts correctly: The scale includes 5-lower and 5-upper. Sorted as text the order breaks; comparison uses the real scale, so “4 and above” filters as expected.

How to use it

Open it
The latest report appears automatically, rechecked every 90 seconds.
See where it was felt
Prefectures are listed strongest first.
Look back
Load the history to filter the last few months by intensity.

Terms and how to read them

Magnitude versus intensity: Magnitude measures the earthquake — one value per event. Intensity measures shaking at a place and differs across locations.
The sequence of reports: A preliminary intensity report comes first, followed by fuller information with epicentre and magnitude. Measured here: about 2 minutes 30 seconds from the event to the first report.
5-lower and 5-upper: Levels 5 and 6 are each split in two, a refinement made in 1996. The difference is visible in the damage.
Depth and how it shakes: At the same magnitude, a shallow focus shakes harder directly above and over a smaller area. A deep one does the opposite, and places far from the epicentre can shake more than those near it. That inversion happens because the structure underground carries the energy preferentially in some directions.
What the reports say about tsunami: Each report states whether a tsunami is a concern — often explicitly "no tsunami is expected from this earthquake" — and a separate tsunami forecast may follow. ⚠️ This tool only displays what has been published, so never use it to decide about a tsunami. Near the coast, strong shaking means move to high ground without waiting for any announcement.
The word aftershock: JMA now often avoids it in favour of "seismic activity". Calling something an aftershock invites the assumption that it will be smaller, and in practice a larger earthquake can follow the first. Even as the count falls off, expecting more shaking of similar size is closer to how these sequences behave.

Questions

Can I use this as an early warning?: No. An early warning is worth having because it arrives seconds before the shaking; this approach cannot — measured at roughly 2 minutes 30 seconds from event to publication. Beyond that, anything that depends on a tab being open and the network being up fails silently. Use broadcast media or an official disaster app built for the purpose.
How often does it refresh?: Every 90 seconds while you are looking at the tab, and not at all while it is hidden — so abandoned tabs do not keep hitting JMA’s servers.
Where does the data come from?: JMA’s published feed and report documents, read directly by your browser. Nothing passes through this site and nothing is altered.
How much data does it use?: About 2KB to check for news and 1–2KB for a report — transfer sizes, measured in August 2026; they rise and fall with seismic activity. Only the optional history is larger, at about 40KB.
I felt it but nothing appeared here.: Three likely reasons. The delay before publication (measured at about 2 minutes 30 seconds). Shaking below intensity 1, which is not reported at all. Or the tab was hidden, which pauses refreshing — returning to it reloads. Failing those, what you felt may not have been an earthquake.
Does it cover earthquakes outside Japan?: Only those with a recorded intensity in Japan, or that could send a tsunami to Japan. This displays what JMA publishes, so distant events with no effect on Japan are absent. To follow worldwide seismicity, the USGS public data is the better source.
How far back does the history go?: As far as the published feed carries — which is not far enough for long-term statistics or historical research. Use the seismic intensity database published by JMA for that. The history loads on demand because it is around 40KB — about twenty times the news feed.

Latest report

History

Related tools

Why this one

How to use it

Open it

See where it was felt

Look back

Terms and how to read them

Questions