M5.0 Earthquake 1 km SSW of Tsukuba, Japan — December 1, 2021
2021-12-01 16:58:36 UTC (2021-12-01) · approx. 1:58 AM UTC+9 local
Felt by 210 people across surrounding communities. Aftershock of the M5.8 mainshock.
On December 1, 2021 at 16:58 UTC, a magnitude 5.0 shallow crustal earthquake struck 1 km SSW of Tsukuba, Japan, at a depth of 51.7 km and coordinates 36.1875°, 140.0911°.
Physical scale: An earthquake of magnitude 5.0 releases seismic energy equivalent to roughly 477 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 1.7 km — 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 5.8 mainshock that occurred 26 days ago 5 km E of Ushiku, 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
Did You Feel It? — community-reported shaking
Aggregated felt-report intensity from 210 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
140.0911°E
Technical Information
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Common Questions
How strong was the magnitude 5.0 earthquake near Tsukuba, Japan?
The magnitude 5.0 earthquake that struck 1 km SSW of Tsukuba, Japan on December 1, 2021 at 16:58 UTC had a depth of 51.7 km. For context, this was a moderate earthquake that could be widely felt.
Where did the earthquake occur?
The earthquake epicenter was located at 36.1875°, 140.0911°, which is 1 km SSW of Tsukuba, Japan. View all earthquakes in Japan.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 5.0 earthquakes can continue for days to weeks and gradually diminish over time.
Is this the same earthquake as the M5.8 one earlier?
No. This magnitude 5.0 earthquake is an aftershock of the larger magnitude 5.8 mainshock that occurred earlier 5 km E of Ushiku, 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 5.0 event is significantly smaller than that historical record.
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Location
Authoritative source: USGS event page (event ID: us6000g88v). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, December 1, 2021). M5.0 Earthquake 1 km SSW of Tsukuba, Japan — December 1, 2021. Retrieved December 22, 2025 from https://www.earthquaketracker.org/earthquakes/event/us6000g88v/