M4.4 Earthquake 4 km NNE of Ichihara, Japan — October 7, 2021
2021-10-07 20:11:50 UTC (2021-10-07) · approx. 5:11 AM UTC+9 local
On October 7, 2021 at 20:11 UTC, a magnitude 4.4 shallow crustal earthquake struck 4 km NNE of Ichihara, Japan, at a depth of 69.5 km and coordinates 35.5528°, 140.1119°.
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 5.8 mainshock that occurred 28 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.
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
140.1119°E
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Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 4.4 earthquake near Ichihara, Japan?
The magnitude 4.4 earthquake that struck 4 km NNE of Ichihara, Japan on October 7, 2021 at 20:11 UTC had a depth of 69.5 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 M5.8 one earlier?
No. This magnitude 4.4 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.
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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: us6000fu1l). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, October 7, 2021). M4.4 Earthquake 4 km NNE of Ichihara, Japan — October 7, 2021. Retrieved December 10, 2021 from https://www.earthquaketracker.org/earthquakes/event/us6000fu1l/