M4.6 Earthquake Honmachi, Japan

On July 29, 2026 at 14:02 UTC, a magnitude 4.6 shallow crustal earthquake struck 10 km W of Honmachi, Japan, at a depth of 10.0 km and coordinates 32.5115°, 130.4901°. This earthquake was detected by 71 seismic stations with good location accuracy and was assigned a USGS significance rating of 326, placing it among routine seismic activity.

Physical scale: An earthquake of magnitude 4.6 releases seismic energy equivalent to roughly 120 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 899 m — a useful intuition for the size of the slip patch on the fault.

This earthquake is part of an ongoing aftershock sequence following the magnitude 5.4 mainshock that occurred 2 hours ago 11 km N of Tsunagi, Japan. Since the mainshock, the USGS has recorded 3 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.

The epicenter is located in Japan, a region characterized by the intersection of four tectonic plates — Pacific, Philippine Sea, Eurasian, and North American — creating multiple subduction zones. The nearest mapped fault system is the Japan Trench. View all earthquakes in Japan.

Learn more: Magnitude scale · Aftershock sequences

Common Questions

How strong was the magnitude 4.6 earthquake near Honmachi, Japan?

The magnitude 4.6 earthquake that struck 10 km W of Honmachi, Japan on July 29, 2026 at 14:02 UTC had a depth of 10.0 km. For context, this was a light earthquake commonly felt near the epicenter.

Where did the earthquake occur?

The earthquake epicenter was located at 32.5115°, 130.4901°, which is 10 km W of Honmachi, Japan. View all earthquakes in Japan.

Were there aftershocks?

Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.6 earthquakes can continue for several days and gradually diminish over time.

Is this the same earthquake as the M5.4 one earlier?

No. This magnitude 4.6 earthquake is an aftershock of the larger magnitude 5.4 mainshock that occurred earlier 11 km N of Tsunagi, Japan. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.

Has Japan had earthquakes this big before?

The largest recorded earthquake in Japan was the M9.1 Tohoku earthquake of March 11, 2011. Today's magnitude 4.6 event is significantly smaller than that historical record.

M4.6 Earthquake 10 km W of Honmachi, Japan — July 29, 2026

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