M4.7 Earthquake southeast of the Loyalty Islands — July 13, 2026

On July 13, 2026 at 15:14 UTC, a magnitude 4.7 shallow crustal earthquake struck southeast of the Loyalty Islands, at a depth of 10.0 km and coordinates -22.8636°, 171.5407°. This earthquake was detected by 40 seismic stations with good 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.

Active aftershock sequence: This earthquake is the mainshock of an ongoing aftershock sequence. In the 6 hours since the mainshock, the USGS has recorded 5 aftershocks within 20 km of the epicenter, including 5 of magnitude 3.0 or greater. The strongest aftershock was a magnitude 5.1 event 4 hours ago. Aftershock sequences from mainshocks of magnitude 4.7 typically continue for several days and gradually diminish over time, though occasional larger aftershocks remain possible.