Earthquakes in Tonga — Page 4

Seismic activity in Tonga is moderate by global standards, with 16 events recorded in the past 30 days, and 123 of the events on record reached magnitude 5 or above — the level at which damage becomes a genuine concern for vulnerable construction. Tonga sits on the Pacific Ring of Fire, and the depth distribution below shows the subducting slab beneath it directly.

388 earthquakes have been recorded in Tonga in our catalogue, 16 of them in the past 30 days.

The average magnitude is 4.8 and the average focal depth 175 km. 388 events reached magnitude 4 or above and 123 reached magnitude 5 or above.

The strongest earthquake recorded in Tonga in this period was a magnitude 7.5 event near Neiafu, Tonga on 24 March 2026, at a depth of 229 km. A magnitude 7.5 earthquake radiates roughly 2.7 million tons of TNT equivalent in seismic energy.

40% of events here are shallow (under 70 km), 40% intermediate (70–300 km) and 20% deep-focus (over 300 km). That proportion of deep-focus events is the signature of a subduction zone: only a cold slab descending into the mantle stays brittle enough to rupture at those depths.

The deepest event on record here was a magnitude 4.4 earthquake at 573 km beneath Houma, Tonga on 28 January 2025.

By band, the catalogue holds 265 in the magnitude 4 range, 110 in the magnitude 5 range, 10 in the magnitude 6 range, 3 in the magnitude 7 range.

The busiest single day was 30 March 2025, with 10 recorded events.

2 of these events carry a USGS link to NOAA tsunami information. That link flag does not mean a tsunami occurred or that a warning was issued.