USA TODAY 8:28 p.m. EDT October 25, 2013
Some small tsunami-driven waves hit three cities along the east coast.
A magnitude-7.1 earthquake struck off the Fukushima region of Japan early Saturday local time, triggering small waves that hit three cities along a 200-mile stretch of the east coast that was briefly under a tsunami advisory.
The Japan Meteorological Agency, which canceled the advisory, said that the first waves hit Soma, Kamaishi, and Ishinomaki-shi Ayukama, but that none topped 3 feet, the threshold for issuing a stronger warning.
There were no reports of damage or serious injuries from the quake, which the agency said was an aftershock of the deadly March 2011 disaster that killed 19,000 and devastated one of the Fukushima nuclear plants.
The epicenter of the 2:10 a.m. quake was located 231 miles east of Japan's Honshu Island at a depth of 6 miles, according to the U.S. Geological Service. The tremor was felt 300 miles away in Tokyo.
The USGS, which initially reported the quake at a magnitude of 7.3, later downgraded it to 7.1. The meteorological agency revised its initial estimate from magnitude 7.1 to 6.8.
The quake prompted the tsunami advisory for an area stretching from the northern edge of Iwate Prefecture to the southern tip of Chiba Prefecture. Three aftershocks occurred during the next four hours, the strongest registering magnitude 5.5.
USA TODAY reporter William Welch said he was asleep in a Tokyo hotel room when the earthquake woke him up at 3:10 a.m. local time. Welch, who has felt many earthquakes while at his home in California, said Saturday's earthquake varied in intensity and "seemed to be the longest one I've experienced."
USGS said the quake was caused by "normal faulting in the shallow oceanic crust of the Pacific plate," near the region of the magnitude-9 Tohoku earthquake in March 2011, which killed about 19,000 people.
The Japan Meteorological Agency issued its initial tsunami warning at 1:14 p.m. ET for Fukushima Prefecture, warning residents to "get out of the water and leave the coast immediately." The warning was later expanded to include Iwate, Miyagi, Ibaraki, and Chiba Prefectures.