An earthquake of preliminary magnitude 5.6 struck Fukushima Prefecture and surrounding areas on Thursday morning but posed no tsunami threats, the Meteorological Agency said.

The operator of the damaged Fukushima No. 1 nuclear power plant said it detected nothing out of the ordinary as a result of the 9:11 a.m. temblor, which occurred in the Pacific Ocean off the Fukushima coast at a depth of around 40 km.

The quake registered up to 4 on the Japanese seismic scale of 1 to 7 in parts of Fukushima and Miyagi prefectures, and was felt in a wide swath of eastern Japan, including Tokyo.