Fukushima hit by 6.8 quake. Tsunami warning issued.

   

A powerful earthquake struck early Saturday off the coast of northern Japan -- rattling nerves in a region rocked three years ago by a deadly tremor, tsunami and nuclear crisis, though thankfully the latest episode didn't nearly measure up.

The Japan Meteorological Agency at one point issued a tsunami warning, which it later amended to tsunami advisories for coastal regions in Iwate, Miyagi and Fukushima prefectures. The latter is the site of the Fukushima Daiichi nuclear power facility that was the center of a weeks-long radioactive crisis.

But a large tsunami never materialized.

At 6:15 a.m. Saturday (5:15 p.m. ET Friday), the same agency noted that all tsunami advisories had been canceled.

Whereas before the JMA urged everyone to "get out of the water and leave the coast immediately," that last update was less alarming. "Pay attention when fishing, swimming or engaging in other activities," the agency noted, "as there may still be slight sea-level changes for the time being."

The Japan Meteorological Agency characterized the quake as a 6.8-magnitude. Yet the U.S. Geological Survey had it a little weaker, downgrading its earlier estimate in calling it a 6.5-magnitude tremor.

According to the USGS, the quake was centered off Honshu island some 129 kilometers (79 miles) east-southeast of Namie and 284 kilometers east-northeast of Tokyo. It was 11 kilometers, or 7 miles, deep.