Footage shows the moment the quake was felt in Yokohama and Tokyo A powerful undersea earthquake south of Japan has shaken buildings in Tokyo and been felt across the country. The US Geological Survey said the 7.8-magnitude earthquake was centred 874km (543 miles) from the Japanese capital, at a depth of more than 660km. The earthquake struck at 20:30 local time (11:30 GMT). Buildings in the capit