Iwaki City is about 43 kilometers south of Fukushima I Nuclear Power Plant. According to the Nuclear and Industrial Safety Agency, there has been no report of any damage at Fukushima I and Fukushima II.
The M6.4 earthquake hit at 3:54AM Japan Standard Time on July 31. It was felt throughout Hokkaido, Tohoku, Kanto, and Chubu (eastern half of Japan). Naraha-machi, where Fukushima II Nuke Plant is located, had the seismic intensity of 5+.
The earthquake was followed by several aftershocks in the same area and Hokkaido.
For more, go to the Japan Meteorological Agency's earthquake site: