M4.9 Earthquake 220 km E of Levuka, Fiji — October 12, 2023

On October 12, 2023 at 05:00 UTC, a magnitude 4.9 deep-focus earthquake struck 220 km E of Levuka, Fiji, at a depth of 551.0 km and coordinates -17.8504°, -178.6112°. This earthquake was detected by 136 seismic stations with excellent location accuracy and was assigned a USGS significance rating of 369, placing it among routine seismic activity.

Physical scale: An earthquake of magnitude 4.9 releases seismic energy equivalent to roughly 338 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 1.4 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 5.4 mainshock that occurred 3 days ago 216 km E of Levuka, Fiji. Since the mainshock, the USGS has recorded 5 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