A major earthquake struck off the coast of Japan just before 6 a.m. local time Tuesday, prompting tsunami warnings and raising fears of a repeat of the deadly 2011 quake and tsunami because of its proximity to the Fukushima Prefecture.
Although the Nikkei opened in the green, the index fell more than 50 points in early trade, then recovered somewhat, trading 10.37 points, or 0.06%, lower.
The earthquake was a 6.9 magnitude, according to the United States Geological Survey, and was at a depth of 11.4 kilometers (7.1 miles) under the ocean, 37 kilometers offshore.
The quake sparked tsunami warnings for both the Fukushima and the Miyagi prefectures, which the Japan Meteorological Agency downgraded to advisories less than an hour after the quake.
The biggest concern was for the Fukushima Daiichi nuclear power plant that was devastated by the 2011 quake; 20,000 people died as the result of that disaster.
Only slightly higher-than-normal waves were reported in the area following the Tuesday morning quake, according to CNN.
A cooling pump at the plant briefly stopped following the quake but was put back into operation, CNN reported, citing a spokesman for the Tokyo Electric Power Company. No abnormalities or change in radiation levels were reported.