A minor tsunami hit Japan's northeastern coastline Wednesday, NHK television reported, after a strong earthquake rocked the region nearly a year on from Japan's worst post-war natural disaster. The 10-centimetre (four inch) wave and 6.8 magnitude quake, which struck some 210 kilometres (130 miles) off the northern island of Hokkaido, prompted local authorities to issue an evacuation warning for coastal residents. Japan's meteorological agency had initially said the tsunami could be as high as 50 centimetres, but US monitors said there was no Pacific-wide tsunami threat. The warning comes after a 9.0-magnitude earthquake triggered a monster tsunami on March 11 last year that killed more than 19,000 people and crippled Japan's Fukushima nuclear plant, sparking the world's worst atomic accident in a generation. There were no reports of damage at nuclear facilities in the area affected by Wednesday's 6.8 quake, the Kyodo news agency said.