M4.8 Earthquake southeast of the Loyalty Islands — December 1, 2021
2021-12-01 21:21:00 UTC (2021-12-01) · approx. 8:21 AM UTC+11 local
Aftershock of the M5.5 mainshock.
On December 1, 2021 at 21:21 UTC, a magnitude 4.8 shallow crustal earthquake struck southeast of the Loyalty Islands, at a depth of 10.0 km and coordinates -23.0516°, 171.4441°.
Physical scale: An earthquake of magnitude 4.8 releases seismic energy equivalent to roughly 239 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 1.2 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 5.5 mainshock that occurred 10 days ago southeast of the Loyalty Islands. 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
171.4441°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 4.8 earthquake southeast of the Loyalty Islands?
The magnitude 4.8 earthquake that struck southeast of the Loyalty Islands on December 1, 2021 at 21:21 UTC had a depth of 10.0 km. For context, this was a light earthquake commonly felt near the epicenter.
Where did the earthquake occur?
The earthquake epicenter was located at -23.0516°, 171.4441°, which is southeast of the Loyalty Islands.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.8 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M5.5 one earlier?
No. This magnitude 4.8 earthquake is an aftershock of the larger magnitude 5.5 mainshock that occurred earlier southeast of the Loyalty Islands. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
Actions
Authoritative source: USGS event page (event ID: us6000ga1h). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, December 1, 2021). M4.8 Earthquake southeast of the Loyalty Islands — December 1, 2021. Retrieved December 22, 2025 from https://www.earthquaketracker.org/earthquakes/event/us6000ga1h/