A magnitude 6.7 earthquake rocked northern Japan Tuesday morning, triggering a tsunami alert.

The quake struck off the coast of Iwate Prefecture at 6:06 a.m., with its epicenter recorded 50 miles north of Miyako and 330 miles north of Tokyo. 

Some local fishermen said they saw small waves of 10 to 20 centimeters reaching the coast.

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There were no initial reports of damages or injuries from the quake.

The Japan Meteorological Agency (JMA) had warned people to stay away from the shore due to possible 3-feet-high waves.  JMA later canceled its tsunami advisory.

The city of Ofunato in Iwate had also issued an evacuation advisory to more than a thousand of its households.

The JMA had described Tuesday's 6.7 quake as an aftershock to the magnitude 9.0 temblor that jolted Japan in March 11, 2011.

The 2011 powerful quake killed at least 15,800 people.  The Fukushima Daiichi Nuclear Power plant's three reactors also suffered a meltdown.

"Because the 3/11 earthquake had such a strong impact, and because it's an area where it was affected by the 3/11 earthquake, we are describing this as an aftershock," said JMA seismologist Yasuhiro Yoshida.

In its Twitter account, the Tokyo Electric Power Company (TEPCO), which operates the Fukushima Daiichi Nuclear Power Plant, said no irregularities have been recorded at their nuclear power plants following the latest quake.

Onagawa Nuclear Power Plant in Miyagi Prefecture also said bullet trains continue to operate at regular schedule and that there are no disruptions recorded due to the earthquake.

Japan Nuclear Fuel also declared no irregularities at its fuel reprocessing facility or other plants in Aomori.

The Iwate Prefecture has a total population of around 1.3 million and is rocked by moderate quakes several times in a month.

About 20 percent of the world's earthquakes, with strength measuring magnitude 6 or higher, happen in Japan.

Tagsearthquake, USGS, jma, iwate prefecture