M4.6 Earthquake 83 km NE of Hihifo, Tonga — February 28, 2025

On February 28, 2025 at 23:27 UTC, a magnitude 4.6 shallow crustal earthquake struck 83 km NE of Hihifo, Tonga, at a depth of 10.0 km and coordinates -15.4631°, -173.1991°. This earthquake was detected by 26 seismic stations with excellent location accuracy and was assigned a USGS significance rating of 326, placing it among routine seismic activity.

Physical scale: An earthquake of magnitude 4.6 releases seismic energy equivalent to roughly 120 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 899 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 19 days ago 89 km NE of Hihifo, Tonga. 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 Tonga, a region characterized by the Tonga-Kermadec subduction zone, where the Pacific Plate descends at up to 240 mm per year — the fastest plate convergence on Earth. The nearest mapped fault system is the Tonga Trench. View all earthquakes in Tonga.

Learn more: Magnitude scale · Aftershock sequences