M5.1 Earthquake west of Macquarie Island — December 31, 2025
2025-12-31 04:00:27 UTC (2025-12-31) · approx. 2:00 PM UTC+10 local
Aftershock of the M5.7 mainshock.
On December 31, 2025 at 04:00 UTC, a magnitude 5.1 shallow crustal earthquake struck west of Macquarie Island, at a depth of 10.0 km and coordinates -57.2022°, 147.7687°. This earthquake was detected by 36 seismic stations with excellent location accuracy and was assigned a USGS significance rating of 400, placing it among routine seismic activity.
Physical scale: An earthquake of magnitude 5.1 releases seismic energy equivalent to roughly 674 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 2.0 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 5.7 mainshock that occurred 21 days ago west of Macquarie Island. 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
147.7687°E
Technical Information
Common Questions
How strong was the magnitude 5.1 earthquake west of Macquarie Island?
The magnitude 5.1 earthquake that struck west of Macquarie Island on December 31, 2025 at 04:00 UTC had a depth of 10.0 km. For context, this was a moderate earthquake that could be widely felt.
Where did the earthquake occur?
The earthquake epicenter was located at -57.2022°, 147.7687°, which is west of Macquarie Island.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 5.1 earthquakes can continue for days to weeks and gradually diminish over time.
Is this the same earthquake as the M5.7 one earlier?
No. This magnitude 5.1 earthquake is an aftershock of the larger magnitude 5.7 mainshock that occurred earlier west of Macquarie Island. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
What should I do after an earthquake?
If you were in the affected area: check yourself and others for injuries, inspect your home for damage, and be prepared for aftershocks.
Actions
Authoritative source: USGS event page (event ID: us7000rln0). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2025, December 31, 2025). M5.1 Earthquake west of Macquarie Island — December 31, 2025. Retrieved April 1, 2026 from https://www.earthquaketracker.org/earthquakes/event/us7000rln0/