Two strong earthquakes shook northern Japan Thursday, but neither caused any apparent damage or prompted a tsunami warning.
Japan's Meteorological Agency said a magnitude 6.1 undersea quake struck Thursday evening about 750 kilometers northeast of Tokyo, near Hokkaido island.
A magnitude 6.0 undersea quake struck early Thursday morning, 244 kilometers northeast of Tokyo.
The Japanese television network NHK said the second tremor left several thousand homes without power.
The quakes did not affect the badly damaged Fukushima nuclear power plant that was crippled by the massive quake and ensuing tsunami that struck in March.
Japan lies on the so-called "Ring of Fire," an arc of earthquake and volcanic zones that stretches around the Pacific Rim. About 90 percent of the world's quakes occur in the region.
The March 11 magnitude 9.0 earthquake and tsunami devastated large parts of Japan's northeastern coast and left nearly 20,000 people dead or missing.
The twin disasters also triggered a nuclear crisis, forcing tens of thousands of people to flee their homes due to leaking radiation.
Some information for this report was provided by AP and AFP.