SENDAI, JAPAN: A magnitude-7.1 aftershock has rattled Japan on the one-month anniversary of a massive earthquake that spawned a deadly tsunami.The epicentre is close to the nuclear plant crippled by the tsunami a month ago. The US geological survey said the 7.1 magnitude onshore quake hit with a depth of just 10 kilometres (six miles), its epicentre 86 kilometres south-southeast of Fukushima city.Japan's meteorological agency issued a tsunami warning saying a one-metre (three feet) wave could hit Ibaraki prefecture, the area worst hit by last month's massive tsunami. The tsunami alert was later lifted after about an hour.The aftershock shook buildings and briefly forced Tokyo's main international airport to close both of its runways, but there have been no immediate reports of damage or injuries.Another 7.1 aftershock had shook the northeast coast last week. There was no tsunami after that quake.People at a large electronics store in central Sendai screamed and ran outside, though the shaking made it hard to move around. Mothers grabbed their children, and windows shook. After a minute or two, people returned to the store.The operator of the crippled Fukushima Dai-ichi nuclear complex says the latest quake briefly cut power but it was quickly restored. Operations there are not endangered.