M4.2 Earthquake 59 km E of Iwaki, Japan — September 8, 2021
2021-09-08 22:16:55 UTC (2021-09-08) · approx. 7:16 AM UTC+9 local
On September 8, 2021 at 22:16 UTC, a magnitude 4.2 shallow crustal earthquake struck 59 km E of Iwaki, Japan, at a depth of 7.3 km and coordinates 37.1179°, 141.5455°.
Physical scale: An earthquake of magnitude 4.2 releases seismic energy equivalent to roughly 30 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 476 m — a useful intuition for the size of the slip patch on the fault.
Earthquake Details
141.5455°E
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Common Questions
How strong was the magnitude 4.2 earthquake near Iwaki, Japan?
The magnitude 4.2 earthquake that struck 59 km E of Iwaki, Japan on September 8, 2021 at 22:16 UTC had a depth of 7.3 km. For context, this was a light earthquake commonly felt near the epicenter.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.2 earthquakes can continue for several days and gradually diminish over time.
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Understanding This Data
Magnitude 4.2 earthquakes are often felt but rarely cause damage.
Authoritative source: USGS event page (event ID: us7000fbgl). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, September 8, 2021). M4.2 Earthquake 59 km E of Iwaki, Japan — September 8, 2021. Retrieved November 17, 2021 from https://www.earthquaketracker.org/earthquakes/event/us7000fbgl/