7.1 magnitude earthquake hits off Japan coast, tsunami warning issued

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.

Photos: Japan’s earthquake, tsunami in March

Officials initially said Thursday’s aftershock was a 7.4-magnitude that hit 25 miles under the water and off the coast of Miyagi prefecture. After the incident was reviewed by a seismologist, the quake was downgraded to a 7.1 magnitude by the U.S. Geological Survey. 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.

USGS officials said the temblor struck off the eastern coast about 41 miles east of Sendai and 73 miles from Fukushima. It was about 207 miles from Tokyo.

The Japan Meteorological Agency warned of tsunami heights as high as 6.6 feet in Miyagi prefecture, while a tsunami advisory warning of waves as high as 1.6 feet were issued for the neighboring prefectures of Fukushima, Ibaraki, Iwate and Aomori prefectures. The warning was lifted 90 minutes after the earthquake struck.

The quake’s 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.

A Pacific Tsunami Warning Center evaluation of the quake said an ocean-wide tsunami was not expected and U.S. officials said there was no expectation of problems on the U.S. West Coast.

Times staff writer Rong-Gong Lin II contributed to this report