M4.8 Earthquake 9 km ENE of Komoro, Japan — April 20, 2021
2021-04-20 17:39:58 UTC (2021-04-20) · approx. 2:39 AM UTC+9 local
Felt by 3 people across nearby locations.
On April 20, 2021 at 17:39 UTC, a magnitude 4.8 intermediate depth earthquake struck 9 km ENE of Komoro, Japan, at a depth of 169.3 km and coordinates 36.3374°, 138.5331°.
Physical scale: An earthquake of magnitude 4.8 releases seismic energy equivalent to roughly 239 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 1.2 km — 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
Did You Feel It? — community-reported shaking
Aggregated felt-report intensity from 3 citizen responses to the USGS Did You Feel It? system. Each colored zone represents the average MMI from reports in that area.
Source: U.S. Geological Survey Did You Feel It?. View on USGS · submit your own report
Earthquake Details
138.5331°E
Technical Information
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Common Questions
How strong was the magnitude 4.8 earthquake near Komoro, Japan?
The magnitude 4.8 earthquake that struck 9 km ENE of Komoro, Japan on April 20, 2021 at 17:39 UTC had a depth of 169.3 km. For context, this was a light earthquake commonly felt near the epicenter.
Where did the earthquake occur?
The earthquake epicenter was located at 36.3374°, 138.5331°, which is 9 km ENE of Komoro, Japan. View all earthquakes in Japan.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.8 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 4.8 event is significantly smaller than that historical record.
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Location
Authoritative source: USGS event page (event ID: us6000e3al). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, April 20, 2021). M4.8 Earthquake 9 km ENE of Komoro, Japan — April 20, 2021. Retrieved July 3, 2021 from https://www.earthquaketracker.org/earthquakes/event/us6000e3al/