Japan hit by major quake

(Vatican Radio) The quake was magnitude 7.3. It struck off northeastern Japan, where last year's tsunami left at least 18-thousand people dead.

This time, Japan's meteorological agency said it released a public warning six minutes before the quake struck.

Tsunami sirens sounded, sending thousands of residents heading for higher ground and to designated evacuation centres such as local schools.

The manager of one such centre told Japan's NHK broadcaster the evacuation was taking place calmly.

The wave proved to be just one metre in height; it did little damage.

But the quake was so strong it caused buildings in Tokyo to sway for a minute or more. Office workers gathered around TV sets bracing for the worst, and phone lines were overloaded.

Japan has barely begun to rebuild after last year's disasters. The Fukushima nuclear plant remains fragile and vulnerable to continued seismic shocks.

And by one count, a third of a million people remain displaced, living in temporary accommodation, so Friday's earthquake seemed to catch the nation at a time when it's still vulnerable.

Listen to Alastair Wanklyn, reporting from Tokyo: