Japan's 7.7 magnitude earthquake

The tremor shook large buildings in Tokyo and triggered immediate tsunami warnings for northern coastal areas.

While only six minor injuries were reported, the event has reignited fears of a repeat of the devastating 2011 disaster.

The infrastructure ministry is now asking hundreds of municipalities to inspect sewer pipes and other critical systems.

Authorities are urging the public to prepare for possible evacuations as the risk of a follow-up earthquake remains elevated.