M4.2 Earthquake 106 km S of Koshima, Japan — December 5, 2020
2020-12-05 23:21:48 UTC (2020-12-05) · approx. 8:21 AM UTC+9 local
On December 5, 2020 at 23:21 UTC, a magnitude 4.2 shallow crustal earthquake struck 106 km S of Koshima, Japan, at a depth of 27.3 km and coordinates 29.2771°, 130.6048°.
Physical scale: An earthquake of magnitude 4.2 releases seismic energy equivalent to roughly 30 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 476 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 5.1 mainshock that occurred 22 days ago 99 km S of Yudomari, 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.
Earthquake Details
130.6048°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 4.2 earthquake near Koshima, Japan?
The magnitude 4.2 earthquake that struck 106 km S of Koshima, Japan on December 5, 2020 at 23:21 UTC had a depth of 27.3 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 4.2 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M5.1 one earlier?
No. This magnitude 4.2 earthquake is an aftershock of the larger magnitude 5.1 mainshock that occurred earlier 99 km S of Yudomari, Japan. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
Actions
Location
Understanding This Data
Magnitude 4.2 earthquakes are often felt but rarely cause damage.
Authoritative source: USGS event page (event ID: us7000cpi7). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2020, December 5, 2020). M4.2 Earthquake 106 km S of Koshima, Japan — December 5, 2020. Retrieved February 12, 2021 from https://www.earthquaketracker.org/earthquakes/event/us7000cpi7/