M4.5 Earthquake south of the Fiji Islands — September 21, 2024

On September 21, 2024 at 22:12 UTC, a magnitude 4.5 intermediate depth earthquake struck south of the Fiji Islands, at a depth of 80.3 km and coordinates -24.0193°, -176.7237°. This earthquake was detected by 29 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.

This earthquake is part of an ongoing aftershock sequence following the magnitude 5.1 mainshock that occurred 7 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