M4.5 Earthquake Miyako, Japan

On August 3, 2026 at 15:54 UTC, a magnitude 4.5 shallow crustal earthquake struck 123 km E of Miyako, Japan, at a depth of 35.0 km and coordinates 39.6999°, 143.3753°. This earthquake was detected by 30 seismic stations with good location accuracy and was assigned a USGS significance rating of 312, placing it among routine seismic activity.

Physical scale: An earthquake of magnitude 4.5 releases seismic energy equivalent to roughly 85 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 767 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 5.1 mainshock that occurred 20 days ago 133 km ENE of Miyako, Japan. Since the mainshock, the USGS has recorded 0 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 4.5 earthquake near Miyako, Japan?

The magnitude 4.5 earthquake that struck 123 km E of Miyako, Japan on August 3, 2026 at 15:54 UTC had a depth of 35.0 km. For context, this was a light earthquake commonly felt near the epicenter.

Where did the earthquake occur?

The earthquake epicenter was located at 39.6999°, 143.3753°, which is 123 km E of Miyako, Japan. View all earthquakes in Japan.

Were there aftershocks?

Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.5 earthquakes can continue for several days and gradually diminish over time.

Is this the same earthquake as the M5.1 one earlier?

No. This magnitude 4.5 earthquake is an aftershock of the larger magnitude 5.1 mainshock that occurred earlier 133 km ENE of Miyako, 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 4.5 event is significantly smaller than that historical record.

M4.5 Earthquake 123 km E of Miyako, Japan — August 3, 2026

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