M4.5 Earthquake 36 km SW of Yonakuni, Japan — August 11, 2020
2020-08-11 23:07:26 UTC (2020-08-11) · approx. 7:07 AM UTC+8 local
Aftershock of the M5.6 mainshock.
On August 11, 2020 at 23:07 UTC, a magnitude 4.5 shallow crustal earthquake struck 36 km SW of Yonakuni, Japan, at a depth of 15.4 km and coordinates 24.2201°, 122.7541°.
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 5.6 mainshock that occurred 10 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.
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
122.7541°E
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Common Questions
How strong was the magnitude 4.5 earthquake near Yonakuni, Japan?
The magnitude 4.5 earthquake that struck 36 km SW of Yonakuni, Japan on August 11, 2020 at 23:07 UTC had a depth of 15.4 km. For context, this was a light earthquake commonly felt near the epicenter.
Where did the earthquake occur?
The earthquake epicenter was located at 24.2201°, 122.7541°, which is 36 km SW of Yonakuni, 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 M5.6 one earlier?
No. This magnitude 4.5 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.
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.
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Authoritative source: USGS event page (event ID: us6000bd0d). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2020, August 11, 2020). M4.5 Earthquake 36 km SW of Yonakuni, Japan — August 11, 2020. Retrieved October 21, 2020 from https://www.earthquaketracker.org/earthquakes/event/us6000bd0d/