M4.7 Earthquake south of the Fiji Islands — September 25, 2023
2023-09-25 05:21:56 UTC (2023-09-25) · approx. 5:21 PM UTC-12 local
Aftershock of the M5.1 mainshock.
On September 25, 2023 at 05:21 UTC, a magnitude 4.7 intermediate depth earthquake struck south of the Fiji Islands, at a depth of 98.0 km and coordinates -24.5106°, -177.0001°. This earthquake was detected by 53 seismic stations with excellent location accuracy and was assigned a USGS significance rating of 340, placing it among routine seismic activity.
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 22 days ago south of the Fiji 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.
The epicenter is located in Fiji, a region characterized by the Fiji Fracture Zone at the junction of the Pacific and Australian plates, with deep-focus seismicity from the subducted slab. View all earthquakes in Fiji.
Learn more: Magnitude scale · Aftershock sequences
Earthquake Details
-177.0001°E
Technical Information
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Common Questions
How strong was the magnitude 4.7 earthquake south of the Fiji Islands?
The magnitude 4.7 earthquake that struck south of the Fiji Islands on September 25, 2023 at 05:21 UTC had a depth of 98.0 km. For context, this was a light earthquake commonly felt near the epicenter.
Where did the earthquake occur?
The earthquake epicenter was located at -24.5106°, -177.0001°, which is south of the Fiji Islands. View all earthquakes in Fiji.
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 south of the Fiji Islands. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
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Location
Authoritative source: USGS event page (event ID: us7000kxxs). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2023, September 25, 2023). M4.7 Earthquake south of the Fiji Islands — September 25, 2023. Retrieved December 9, 2023 from https://www.earthquaketracker.org/earthquakes/event/us7000kxxs/