ISTANBUL A 5.0-magnitude earthquake struck Japan's eastern Ibaraki prefecture Wednesday, with tremors felt in central Tokyo. No tsunami warning has been issued, Kyodo News Agency reported. The quake occurred at a depth of 50 kilometers (31 miles), said the Japan Meteorological Agency. No casualties or significant property damage have been reported so far, while the Tokai No. 2 Nuclear Power Station in Ibaraki prefecture has confirmed no abnormalities. The Shinkansen bullet train service between