Earthquakes in Tonga — December 2025

18 earthquakes were recorded in Tonga during December 2025, an average of 0.6 per day.

18 reached magnitude 4 or above and 0 reached magnitude 5 or above. The average focal depth was 261 km.

The month's largest event in Tonga was a magnitude 4.9 earthquake near Pangai, Tonga on 11 December 2025 at 10:37 UTC. A magnitude 4.9 earthquake radiates roughly 338 tons of TNT equivalent in seismic energy.

That is close to the Tonga monthly average of 18 events over the period we cover, and up from the 16 recorded the previous month.

22% of events here are shallow (under 70 km), 39% intermediate (70–300 km) and 39% 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.

By band, the catalogue holds 18 in the magnitude 4 range.

Activity peaked on 19 December, when 3 events were recorded.

The month's largest events were M4.9 near Pangai, Tonga on 11 December at 10 km; M4.9 near Nuku‘alofa, Tonga on 18 December at 207 km; M4.8 near Houma, Tonga on 16 December at 10 km.

That is close to the 18 events Tonga averages per month across the 21 months on record.