M5.1 Earthquake south of the Kermadec Islands — October 21, 2025
2025-10-21 20:02:05 UTC (2025-10-21) · approx. 8:02 AM UTC-12 local
On October 21, 2025 at 20:02 UTC, a magnitude 5.1 shallow crustal earthquake struck south of the Kermadec Islands, at a depth of 10.0 km and coordinates -33.6674°, -178.5047°. This earthquake was detected by 46 seismic stations with good 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.
Earthquake Details
-178.5047°E
Technical Information
Common Questions
How strong was the magnitude 5.1 earthquake south of the Kermadec Islands?
The magnitude 5.1 earthquake that struck south of the Kermadec Islands on October 21, 2025 at 20:02 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 -33.6674°, -178.5047°, which is south of the Kermadec Islands.
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.
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. For detailed guidance, see our earthquake safety guide and emergency planning resources.
Authoritative source: USGS event page (event ID: us6000riiz). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2025, October 21, 2025). M5.1 Earthquake south of the Kermadec Islands — October 21, 2025. Retrieved May 26, 2026 from https://www.earthquaketracker.org/earthquakes/event/us6000riiz/