Japan was rattled by a strong aftershock and tsunami warning Thursday night nearly a month after a devastating earthquake and tsunami flattened the northeastern coast.

The Japan meteorological agency issued a tsunami warning for a wave of up to 6 feet. 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.

However, the Pacific Tsunami Center, operated by the United States, has not issued an oceanwide warning. The center said the Japanese coast could feel "small effects, possibly destructive but in a small local area."

Complete coverage: Disaster in Japan

Officials at Tokyo Electric Power Co., said the aftershock had caused "no problems" at the beleaguered Fukushima Dai-ichi nuclear complex, and that workers had been evacuated to safe ground.

Thursday's aftershock was a 7.4-magnitude and hit 25 miles under the water and off the coast of Miyagi prefecture, officials said. 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 from Sendai and 90 miles from Fukushima. It was about 215 miles from Tokyo.

The depth was 25 miles. 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.

via CBS News.