Powerful earthquake shakes northern Japan

A powerful earthquake shook northern Japan early on Tuesday, triggering small tsunami waves that struck towns along the north-eastern coast about 350km away. There were no immediate reports of damage or injuries.

Japan's Meteorological Agency said the magnitude-7,1 quake hit at 6.39am local time off the east coast of Japan's main island of Honshu, and issued a tsunami warning.

About 400 households along the coast were temporarily ordered to evacuate, public broadcaster NHK reported. Local authorities also ordered fishing boats to move to open water to avoid being washed up on the shore.

Small tsunami waves measuring up to 50cm hit Ofunato city on the coast of Iwate prefecture nearly an hour after the quake, the agency said.

Smaller tsunami waves hit at least four other coastal towns in Iwate, Aomori and Miyagi provinces, but there were no immediate reports of damage.

The agency called off the tsunami warning about two hours after the quake.

Tsunami waves, generated by earthquakes, are often barely noticeable in the ocean, but can rise to great heights once they arrive at shore.

Tuesday's quake shook buildings across a wide area of northern and eastern Honshu, including Tokyo, and Hokkaido.Express train services between Tokyo and north-eastern Japan were temporarily suspended for safety checks, but resumed later, NHK said.

Tokyo's metropolitan area is home to about 35-million residents, or a quarter of Japan's population.

Japan is one of the world's most earthquake-prone countries because it sits atop four tectonic plates. A 7,2-magnitude earthquake shook north-eastern Japan in August, injuring at least 59 people, triggering landslides, damaging buildings and causing widespread power outages.

There was no destructive Pacific Ocean-wide tsunami threat following Tuesday's earthquake, based on historical quake and tsunami data, according to the Pacific Tsunami Warning Centre in Ewa Beach, Hawaii.

However, earthquakes as large as Tuesday's can generate a local tsunami capable of causing destruction along coastlines within 100km of the epicentre, according to the centre.

In 1993, a quake off Japan's northernmost main island of Hokkaido triggered a tsunami measuring 30m tall on Okushiri Island, flattening homes there within minutes. More than 200 people died in the waves, and in fires caused by the quake.A quake with an estimated magnitude of 8,3 hit Tokyo in 1923, killing 142 000 people. Tsunami waves followed that quake, but caused relatively little damage, reports the AP. I.L.