7.3 Japan Earthquake Prompts Tsunami Warning, Fukushima on Alert

A tsunami warning has been issued for the northeastern coast of Japan after a 7.3-magnitude earthquake struck at sea early Saturday morning Japan time, Friday afternoon EDT

Fukushima prefecture, including the patch of coast home to the crippled Fukushima Dai-ichi nuclear reactor, which was destroyed by a tsunami in 2011, is included in the tsunami warning.

Tsunami as high as 1 meter (about 3 feet) could reach Japan's coast, according to reports, though waves of that height have yet to be reported. 

The quake struck at 2:10 a.m. Saturday in Japan (1:10 p.m. Friday, EDT) about 170 miles off the Fukushima coast at a depth of 10 km. Workers near the Dai-ichi power station were ordered to move to higher ground, according to The Associated Press.

There was no sign of damage or elevated radiation at the nuclear campus immediately following the quake, according to news reports.

Japan's Meteorological Association reported the quake as magnitude 7.1 on the Richter scale, and a modest 4 out of 7 on the Japanese seismic scale.

Officials are waring residents to stay clear of the coast, although the quake occurred at an hour where it is unlikely many people would be out and about along the coastline. A typhoon is passing through Japan as well, likely further decreasing the chances of people along the coast in the middle of the night.

The latest reports indicate tsunami between 20cm and 40cm in Iwate and Miyagi prefectures, which are both north of Fukushima prefecture.

There were no immediate reports of damage on land and images of harbors in the tsunami warning zone shown by Japan's national broadcaster NHK showed calm waters.

People in Tokyo, some 300km away from the quake's epicenter, reported feeling swaying for about one minute.

An anonymous user who said they are in Tokyo's Ota ward posted to the independent reporting site Earthquake Report:

"Really long but mellow earthquake. Felt like I was on a boat. It kept going for what seemed to be at least a minute."