Earthquakes in Tonga — September 2026

19 earthquakes were recorded in Tonga during September 2026, an average of 0.6 per day.

19 reached magnitude 4 or above and 6 reached magnitude 5 or above. The average focal depth was 144 km.

The month's largest event in Tonga was a magnitude 5.7 earthquake near Hihifo, Tonga on 23 September 2026 at 14:41 UTC. A magnitude 5.7 earthquake radiates roughly 5,351 tons of TNT equivalent in seismic energy.

That is close to the Tonga monthly average of 19 events over the period we cover, and up from the 17 recorded the previous month.

58% of events here are shallow (under 70 km), 21% intermediate (70–300 km) and 21% 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 13 in the magnitude 4 range, 6 in the magnitude 5 range.

Activity peaked on 20 September, when 5 events were recorded.

The month's largest events were M5.7 near Hihifo, Tonga on 23 September at 10 km; M5.4 near Pangai, Tonga on 29 September at 10 km; M5.3 near Neiafu, Tonga on 08 September at 10 km.

That is close to the 19 events Tonga averages per month across the 23 months on record.