A magnitude 7.4 earthquake near ENE of Miyako, Japan on 20/04/2026 07:52 UTC (depth 25 km) was screened for tsunami potential. Events like this are monitored because of their relevance to the Pacific coast, Alaska and Hawaii.
Event technical data
| Magnitude | M 7.4 |
| Depth | 25 km |
| Coordinates | 39.9993°, 142.9851° |
| Time (UTC) | 2026-04-20 07:52 UTC |
| Location | 97 km ENE of Miyako, Japan |
| Tsunami potential | Moderate |
Tsunami assessment
Assessment: Shallow event capable of generating a local or regional tsunami if the rupture reaches the seafloor. Shallow (<70 km) offshore earthquakes of M7+ are the primary driver of seismic sea waves; depth, location relative to the coast and seafloor displacement govern the actual hazard.
Geotechnical relevance
For coastal geotechnical engineering in the United States, tsunami hazard influences site selection, coastal foundation design, scour and liquefaction in saturated coastal sands, and the resilience of port and waterfront structures. Monitoring tsunamigenic events informs run-up and inundation assumptions.
Official warning system
U.S. NWS Tsunami Warning System (NTWC / PTWC) issues the official tsunami watches, advisories and warnings for the Pacific coast, Alaska and Hawaii. Official tsunami warning portal →
Seismic source data: USGS Earthquake Hazards Program.
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