Japan jolted by 7.4-strong earthquake

Tokyo:  Japan was rattled by a strong aftershock and tsunami warning Thursday night nearly a month after a devastating earthquake and tsunami flattened the north-eastern coast.

The Japan meteorological agency issued a tsunami warning for a wave of up to 6 feet (two metres). The warning was issued for a coastal area already torn apart by last month's tsunami, which is believed to have killed some 25,000 people and has sparked an ongoing crisis at a nuclear power plant.

Officials say Thursday's aftershock was a 7.4-magnitude and hit 25 miles (40 kilometres) under the water and off the coast of Miyagi prefecture. The quake that preceded last month's tsunami was a 9.0-magnitude.

Buildings as far away as Tokyo shook for about a minute.

In Ichinoseki, inland from Japan's eastern coast, buildings shook violently, knocking items from shelves and toppling furniture, but there was no heavy damage to the buildings themselves. Immediately after the quake, all power was cut. The city went dark, but cars drove around normally and people assembled in the streets despite the late hour.

U.S. Geological Survey gave the preliminary magnitude as 7.4 and it struck off the eastern coast 60 miles (100 kilometres) from Sendai and 90 miles (140 kilometres) from Fukushima. It was about 215 miles (345 kilometres) from Tokyo.

The depth was 25 miles (40 kilometres). Shallower quakes tend to be more destructive.

Hundreds of aftershocks have shaken the northeast region devastated by the March 11 earthquake, but few have been stronger than 7.0.

A Pacific Tsunami Warning Centre evaluation of the quake said an ocean-wide tsunami was not expected.