M4.4 Earthquake 4 km SSE of Yotsukaid?, Japan — January 21, 2021
2021-01-21 22:04:24 UTC (2021-01-21) · approx. 7:04 AM UTC+9 local
On January 21, 2021 at 22:04 UTC, a magnitude 4.4 shallow crustal earthquake struck 4 km SSE of Yotsukaid?, Japan, at a depth of 63.9 km and coordinates 35.6157°, 140.1848°.
Physical scale: An earthquake of magnitude 4.4 releases seismic energy equivalent to roughly 60 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 655 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 5.3 mainshock that occurred 1 day ago 0 km NNE of Yōkaichiba, Japan. Since the mainshock, the USGS has recorded 0 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.
Did You Feel It? — community-reported shaking
Aggregated felt-report intensity from 1 citizen response 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
140.1848°E
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Common Questions
How strong was the magnitude 4.4 earthquake near Yotsukaid?, Japan?
The magnitude 4.4 earthquake that struck 4 km SSE of Yotsukaid?, Japan on January 21, 2021 at 22:04 UTC had a depth of 63.9 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 4.4 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M5.3 one earlier?
No. This magnitude 4.4 earthquake is an aftershock of the larger magnitude 5.3 mainshock that occurred earlier 0 km NNE of Yōkaichiba, Japan. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
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Understanding This Data
Magnitude 4.4 earthquakes are often felt but rarely cause damage.
Authoritative source: USGS event page (event ID: us7000d28g). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, January 21, 2021). M4.4 Earthquake 4 km SSE of Yotsukaid?, Japan — January 21, 2021. Retrieved March 27, 2021 from https://www.earthquaketracker.org/earthquakes/event/us7000d28g/