This map shows near real-time seismic activity across the Japanese archipelago and surrounding subduction zones, using live data from Japan Meteorological Agency (JMA). Every circle represents an earthquake recorded within the last seven days. The minimum magnitude shown on this map is M3.0. Japan also benefits from JMA's Earthquake Early Warning system — when an alert is broadcast, a banner appears across the top of the map.
What do the magnitudes mean?
The colour and size of each circle indicates the earthquake's magnitude — the amount of energy released at the source. Here's how to read the scale:
- M3.0 – 3.9 — Minor. Often felt by people near the epicentre, but rarely causes damage. Can feel like a light truck passing.
- M4.0 – 4.9 — Light. Light, noticeable shaking indoors. Dishes might rattle. Unlikely to cause significant damage.
- M5.0 – 5.9 — Moderate. A moderate earthquake. Can damage poorly built buildings and cause minor damage to well-built ones.
- M6.0 – 6.9 — Major. A strong earthquake. Destructive in populated areas, causing significant damage.
- M7.0 + — Great. A major earthquake capable of widespread, heavy damage over large areas.
Why does depth matter?
When you click a circle, you'll see its depth. Depth is a critical factor in how much shaking is felt on the surface:
- Shallow quakes (0–70 km) are often more impactful because seismic energy has less distance to travel before reaching the surface — resulting in stronger, more localised shaking.
- Intermediate (70–300 km) and deep quakes (300+ km) dissipate energy as it travels through the crust, so shaking at the surface is usually less intense even when the magnitude is high.
How to read the map's visuals
The map uses several visual cues to convey time and significance:
- Fading circles: every quake fades over seven days. The more transparent a circle is, the older the event.
- Pulsing rings: events recorded within the last hour have two expanding rings and a brightness pulse to draw the eye to the most recent activity.
- Newest on top: recent quakes are layered above older ones so they never get buried.
- Click any marker — or any item in the events list — to see the exact time, depth, location, and a link to the official JMA report.
Beyond the map
Toggle Fault Lines to overlay continental and intraplate active faults from the Global Earthquake Model database. Toggle Tectonic Plates to see plate regions and their boundaries from Peter Bird's 2003 plate-boundary model (PB2002). For active tsunami warnings, a red banner appears at the top of the map. For historical context, see On This Day for significant M6.5+ events that occurred on today's date since 1900.
Data attribution and source links are listed on the Data Sources page.