M 7.4 earthquake – 100 km ENE of Miyako, Japan | Hacker News

A strong offshore quake near Miyako, Japan was first reported at magnitude 7.4, then revised to 7.7, with shaking felt as far away as Tokyo.

Early alerts from the NERV app and the Japan Meteorological Agency gave residents seconds of warning before the strongest shaking.

Tsunami warnings were issued along the coast, but the initial waves have remained relatively small and no major damage has been indicated so far.

The event highlights how Japan’s warning systems can rapidly mobilize during a distant offshore quake and disrupt transport like the shinkansen.