An earthquake has hit Tokyo, northeast Japan, registering 7.4 magnitude. A tsunami warning has been issued and is said to have already hit parts of the shoreline.

TV footage showed buildings in Tokyo shaking as the 7.4 magnitude quake hit the already damaged region. The tremor continued for about a minute.

The Japan meteorological agency issued a tsunami warning for a wave of up to one meter. Authorities in the coastal regions have been alerted.

Japan’s NHK public television repeatedly said those in areas where the tsunami warnings were issued should evacuate immediately to higher ground.

There have been no reports of casualties from today’s earthquake although people are thought to be injured.

Officials said that today’s earthquake was a 7.4-magnitude and hit 25 miles under the water and off the coast of Miyagi prefecture. The quake that preceded last month’s tsunami was a 9.0-magnitude.

The earthquake is not said to have had any impact on the damaged Fukushima nuclear plant and all workers are said to be safe.

Hundreds of aftershocks have shaken the northeast region of Japan since the April 11 earthquake, but few have been stronger than 7.0.

The earthquake occurred at 11:34 pm local time.

More information will follow.