A magnitude 8.3 (MW) earthquake occurred on 1946-12-20, 04:19 local time (19:19 UTC) (just now), centered Off the coast of Wakayama (140 km SE, Japan). The hypocenter was located at a shallow depth of 15 km. Primary telemetry verified by USGS alongside 1 regional seismic monitoring networks.
Curated Global Seismic Archive (1700–Present)
42.50 Mt TNT
shallow (Shallow crustal)
Injuries: > 5,000 · ~99.9M felt
Timeline of foreshocks, main rupture, aftershocks and machine learning risk probability evolution.
Shaking intensity is modelled from magnitude, depth and distance (GMPE attenuation), not reported by residents.
| Town | Distance | Intensity |
|---|---|---|
| Wakayama · Wakayama | 140 km | MMI VIII |
| Tokushima · Tokushima | 164 km | MMI VIII |
| Ōsaka · Osaka | 186 km | MMI VIII |
| Kōbe · Hyogo | 186 km | MMI VIII |
| Tsu · Mie | 186 km | MMI VIII |
| Ōtsu · Shiga | 210 km | MMI VII |
Independent solutions for the same rupture. Differences of 0.1–0.3 in magnitude are normal and reflect method and station coverage.
| Agency | Source ID | Magnitude | Depth | Epicenter |
|---|---|---|---|---|
USGS Primary | iscgem898698 | M 8.3 | 15 km | 33.12, 135.91 |
Nearest mapped active fault: Unnamed Fault, 5 km away, slip rate ~15.0 mm/yr (GEM Global Active Faults).