M4.6 Earthquake 166 km ESE of Iwaki, Japan — August 27, 2023
2023-08-27 16:41:50 UTC (2023-08-27) · approx. 2:41 AM UTC+10 local
On August 27, 2023 at 16:41 UTC, a magnitude 4.6 shallow crustal earthquake struck 166 km ESE of Iwaki, Japan, at a depth of 10.0 km and coordinates 36.5338°, 142.6293°. This earthquake was detected by 41 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.
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
Earthquake Details
142.6293°E
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Common Questions
How strong was the magnitude 4.6 earthquake near Iwaki, Japan?
The magnitude 4.6 earthquake that struck 166 km ESE of Iwaki, Japan on August 27, 2023 at 16:41 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 36.5338°, 142.6293°, which is 166 km ESE of Iwaki, 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.
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.
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Location
Authoritative source: USGS event page (event ID: us7000krd4). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2023, August 27, 2023). M4.6 Earthquake 166 km ESE of Iwaki, Japan — August 27, 2023. Retrieved November 4, 2023 from https://www.earthquaketracker.org/earthquakes/event/us7000krd4/