M4.1 Earthquake 64 km SSW of Yonakuni, Japan — September 20, 2020
2020-09-20 22:13:09 UTC (2020-09-20) · approx. 6:13 AM UTC+8 local
On September 20, 2020 at 22:13 UTC, a magnitude 4.1 shallow crustal earthquake struck 64 km SSW of Yonakuni, Japan, at a depth of 38.1 km and coordinates 23.9188°, 122.7725°.
Physical scale: An earthquake of magnitude 4.1 releases seismic energy equivalent to roughly 21 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 406 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 5.6 mainshock that occurred 7 days ago 74 km S of Yonakuni, Japan. Since the mainshock, the USGS has recorded 1 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.
Earthquake Details
122.7725°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 4.1 earthquake near Yonakuni, Japan?
The magnitude 4.1 earthquake that struck 64 km SSW of Yonakuni, Japan on September 20, 2020 at 22:13 UTC had a depth of 38.1 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 4.1 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M5.6 one earlier?
No. This magnitude 4.1 earthquake is an aftershock of the larger magnitude 5.6 mainshock that occurred earlier 74 km S of Yonakuni, Japan. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
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Understanding This Data
Magnitude 4.1 earthquakes are often felt but rarely cause damage.
Authoritative source: USGS event page (event ID: us6000c0mp). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2020, September 20, 2020). M4.1 Earthquake 64 km SSW of Yonakuni, Japan — September 20, 2020. Retrieved November 28, 2020 from https://www.earthquaketracker.org/earthquakes/event/us6000c0mp/