Overview
- The offshore quake, which struck Monday at 4:53 p.m. local time off Sanriku/Iwate, was shallow at about 10 kilometers and was later put at magnitude 7.7 by Japan’s weather agency.
- Measured tsunami waves peaked at about 0.8 meters at Kuji in Iwate, and warnings were downgraded to advisories of up to 1 meter before being lifted in many areas.
- Authorities urged roughly 170,000 coastal residents to evacuate to higher ground, and local media reported at least one injury in Aomori.
- Rail operators halted segments of Shinkansen and local lines for safety checks and utilities logged scattered power outages as inspections continued.
- A follow‑up advisory through April 27 warns the chance of a magnitude‑8 quake from Hokkaido to Chiba is about ten times above normal, which officials stress is a precaution based on aftershock statistics rather than a prediction.