M4.5 Earthquake 171 km NNE of Colonia, Micronesia — September 4, 2025
2025-09-04 23:21:11 UTC (2025-09-04) · approx. 8:21 AM UTC+9 local
On September 4, 2025 at 23:21 UTC, a magnitude 4.5 shallow crustal earthquake struck 171 km NNE of Colonia, Micronesia, at a depth of 10.0 km and coordinates 10.9916°, 138.5920°. This earthquake was detected by 17 seismic stations with good location accuracy and was assigned a USGS significance rating of 312, placing it among routine seismic activity.
Physical scale: An earthquake of magnitude 4.5 releases seismic energy equivalent to roughly 85 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 767 m — a useful intuition for the size of the slip patch on the fault.
Earthquake Details
138.5920°E
Technical Information
Common Questions
How strong was the magnitude 4.5 earthquake near Colonia, Micronesia?
The magnitude 4.5 earthquake that struck 171 km NNE of Colonia, Micronesia on September 4, 2025 at 23:21 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 10.9916°, 138.5920°, which is 171 km NNE of Colonia, Micronesia.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.5 earthquakes can continue for several days and gradually diminish over time.
Actions
Authoritative source: USGS event page (event ID: us6000rd81). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2025, September 4, 2025). M4.5 Earthquake 171 km NNE of Colonia, Micronesia — September 4, 2025. Retrieved November 30, 2025 from https://www.earthquaketracker.org/earthquakes/event/us6000rd81/