M4.7 Earthquake 132 km SW of Merizo Village, Guam — September 12, 2021
2021-09-12 22:57:03 UTC (2021-09-12) · approx. 8:57 AM UTC+10 local
Aftershock of the M5.1 mainshock.
On September 12, 2021 at 22:57 UTC, a magnitude 4.7 shallow crustal earthquake struck 132 km SW of Merizo Village, Guam, at a depth of 10.0 km and coordinates 12.2742°, 143.9908°.
Physical scale: An earthquake of magnitude 4.7 releases seismic energy equivalent to roughly 169 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 1.1 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 5.1 mainshock that occurred 10 days ago 163 km SW of Merizo Village, Guam. Since the mainshock, the USGS has recorded 2 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.
Earthquake Details
143.9908°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 4.7 earthquake near Merizo Village, Guam?
The magnitude 4.7 earthquake that struck 132 km SW of Merizo Village, Guam on September 12, 2021 at 22:57 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 12.2742°, 143.9908°, which is 132 km SW of Merizo Village, Guam.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.7 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 4.7 earthquake is an aftershock of the larger magnitude 5.1 mainshock that occurred earlier 163 km SW of Merizo Village, Guam. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
Actions
Authoritative source: USGS event page (event ID: us7000fc3z). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, September 12, 2021). M4.7 Earthquake 132 km SW of Merizo Village, Guam — September 12, 2021. Retrieved December 22, 2025 from https://www.earthquaketracker.org/earthquakes/event/us7000fc3z/