A magnitude 7.7 (MW) earthquake occurred on 1938-05-23, 16:18 local time (07:18 UTC) (just now), centered Sea of Japan (77 km SE of Iwaki, 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)
5.35 Mt TNT
shallow (Shallow crustal)
Injuries: > 5,000 · ~59.9M 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 |
|---|---|---|
| Iwaki · Fukushima | 77 km | MMI VIII |
| Mito · Ibaraki | 89 km | MMI VIII |
| Kōriyama · Fukushima | 137 km | MMI VII |
| Utsunomiya · Tochigi | 142 km | MMI VII |
| Fukushima · Fukushima | 160 km | MMI VII |
| Tokyo · Tokyo | 180 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 | iscgem902498 | M 7.7 | 15 km | 36.53, 141.46 |
Nearest mapped active fault: Takahagi, 5 km away, slip rate ~15.0 mm/yr (GEM Global Active Faults).
View live seismic monitoring, historical danger benchmarks, fault slip models and recurrence intervals for this zone.