An earthquake with a preliminary magnitude of 5.5 hit Japan's Ibaraki Prefecture and its vicinity early Saturday, the Japan Meteorological Agency said. No tsunami warning was issued. The quake registered lower 5 on the Japanese seismic intensity scale of 7 in Takahagi and 4 in several other locations in the prefecture, the official (Kyodo) news agency reported. There has been no report of fresh abnormalities at the Fukushima Daiichi and Daini nuclear power plants in neighboring Fukushima Prefecture.