The coast is being dragged
Off southern Japan, the seafloor is quietly winding up for a giant.
The Nankai Trough is a classic subduction megathrust. An oceanic plate dives under Japan, dragging and straining the landward plate until it snaps back in a magnitude 8 to 9 earthquake. These great quakes have recurred here for well over a thousand years.
What is happening at Nankai Trough
Along the Nankai Trough the Philippine Sea Plate slides beneath southwest Japan. The two plates are locked together over much of the boundary, so strain builds up year after year.
When the locked patch finally gives way, it produces a megathrust earthquake and, because the fault is offshore, a tsunami that can reach the coast in minutes. Japan鈥檚 Earthquake Research Committee treats a future Nankai megaquake as a matter of when, not if.
The hazard record here
THE RECORD HERE
A magnitude 8.3 earthquake struck here in 1946.
Live figures from the QuakeMate hazard API - USGS earthquake catalog, NOAA tsunami database and published recurrence estimates. Some fields are blank where there is no record.
Recent earthquakes at Nankai Trough
- 4.687 km SE of Kumano, Japan4 weeks ago 路 04/07/2026, 02:56:15 路 386 km deep
- 4.6NEAR S. COAST OF WESTERN HONSHU4 weeks ago 路 04/07/2026, 02:56:16 路 400 km deep
- 5.1NEAR S. COAST OF WESTERN HONSHU3 weeks ago 路 09/07/2026, 12:59:03 路 10 km deep
- 5.150 km SW of Shirahama, Japan3 weeks ago 路 09/07/2026, 12:58:57 路 10 km deep
- 3.2NEAR S. COAST OF WESTERN HONSHU4 days ago 路 28/07/2026, 08:16:30 路 10 km deep
- 3.2NEAR S. COAST OF WESTERN HONSHU1 week ago 路 22/07/2026, 22:46:30 路 10 km deep
8 more earthquakes at Nankai Trough
Open the QuakeMate app to see every quake here, sorted and mapped - plus real-time alerts when a new one strikes.
Notable events
5.1Recent2026M5.1 - NEAR S. COAST OF WESTERN HONSHU3 weeks ago 路 tap for full data1707
The Hoei earthquake ruptured the whole trough and was followed by a Mount Fuji eruption.
1944
The M8 Tonankai earthquake struck the eastern segment.
1946
The M8 Nankai earthquake struck the western segment two years later.
What scientists watch
Japan runs seafloor sensors and GPS networks along the trough and issues Nankai Trough advisories when unusual activity is detected.
Staying ahead of it
An offshore megathrust means a tsunami can arrive in minutes - the earliest possible warning saves the most lives.
Get QuakeMate freeGet warned before the next one at Nankai Trough.
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Nankai Trough: common questions
When will the next Nankai Trough earthquake happen?
No one can give a date. Japanese agencies estimate a high probability of a magnitude 8 to 9 event within the coming decades, based on how regularly these great quakes have recurred. QuakeMate delivers the alert the instant one strikes.
Would a Nankai earthquake cause a tsunami?
Yes. Because the fault lies offshore and shallow, a great Nankai quake is expected to send a large tsunami to the coast within minutes, which is why early warning is so critical.
Related hazard zones
Earthquake data via the QuakeMate API (USGS, EMSC and regional agencies). Historical notes summarise well-established events; magnitudes and dates follow the published record. Live figures may be revised.