Japan braces for possible megaquake after 7.7 quake triggers tsunami warnings

A 7.7 magnitude undersea earthquake off Japan's northeast coast prompted a tsunami warning and evacuation orders, with initial fears of waves up to 3 meters; actual waves reached about 80 cm. Tremors were felt in Tokyo and as far as Hokkaido, some trains were disrupted and power outages reported, and officials warned there is a relatively higher risk of a larger quake in the coming week, though the alert was later downgraded to a tsunami alert.