TOKYO >> A strong earthquake shook northern Japan today, but no damage was reported and there was no risk of a tsunami.

The Japan Meteorological Agency recorded a 6.4 preliminary magnitude for the earthquake that struck at 8 p.m. local time (1 a.m. Hawaii time). The agency said there may be a small change in sea levels but did not issue tsunami warnings.

The epicenter was off the coast of Iwate and was about 6 miles below the sea surface.

Iwate is in the region heavily damaged by last year’s earthquake and tsunami. The massive magnitude-9.0 earthquake and tsunami on March 11, 2011, left some 19,000 people dead or missing, wreaked widespread damage along the northeastern coast and triggered the worst nuclear accident since Chernobyl. Rebuilding has yet to fully begin in many coastal communities.

No damage or injury was reported from today’s tremor.

There were no abnormalities reported at nuclear power plants in the region, including the Fukushima Dai-ichi plant that had been crippled by last year’s disasters, operators said. All but one of Japan’s 54 nuclear plants are offline, most of them for safety inspections.