Earthquakes in Japan — September 2025

35 earthquakes were recorded in Japan during September 2025, an average of 1.2 per day.

35 reached magnitude 4 or above and 1 reached magnitude 5 or above. The average focal depth was 49 km.

The month's largest event in Japan was a magnitude 5.3 earthquake near Izu Islands, Japan on 02 September 2025 at 03:32 UTC. A magnitude 5.3 earthquake radiates roughly 1,344 tons of TNT equivalent in seismic energy.

That is below the Japan monthly average of 57 events over the period we cover — a comparatively quiet month, and down from the 41 recorded the previous month.

86% of events here are shallow (under 70 km), 11% intermediate (70–300 km) and 3% deep-focus (over 300 km). The mix is dominated by shallow crustal events, with a minority of intermediate-depth activity.

By band, the catalogue holds 34 in the magnitude 4 range, 1 in the magnitude 5 range.

Activity peaked on 05 September, when 4 events were recorded.

The month's largest events were M5.3 near Izu Islands, Japan on 02 September at 10 km; M4.9 near Kurio, Japan on 17 September at 11 km; M4.9 near Kurio, Japan on 17 September at 10 km.

That is 38% below the 57 events Japan averages per month across the 21 months on record.