M4.5 Earthquake south of Tonga — May 12, 2025

On May 12, 2025 at 20:14 UTC, a magnitude 4.5 shallow crustal earthquake struck south of Tonga, at a depth of 10.0 km and coordinates -24.5799°, -175.2369°. This earthquake was detected by 17 seismic stations with moderate 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 5.2 mainshock that occurred 3 hours ago south of Tonga. Since the mainshock, the USGS has recorded 1 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