A strong earthquake with a preliminary magnitude of 5.4 jolted Nagano Prefecture and its vicinity in central Japan on Thursday morning, injuring at least eight people, the Japan Meteorological Agency said. The quake measured upper 5 on the Japanese seismic scale of 7 in Matsumoto in the prefecture and 4 in Yamagata, also in Nagano, according to Japan\'s News Agency (Kyodo). No tsunami warning was issued. Among the eight injured in Matsumoto were a woman in her 70s, who is suspected of suffering a bone fracture, and a girl in the second grade, who sustained minor injuries after being hit by a collapsing brick wall, according to police.