A strong earthquake shook northern Japan on Wednesday evening, causing small tidal changes on its Pacific coastline but no damage or injury was reported.

Several towns issued evacuation orders or advisories to residents nearest the coast. A swelling of 20 centimeters (8 inches) was observed in the port of Hachinohe in Aomori, northern Japan, about one hour after the quake struck the region. Smaller changes were also reported in several locations on Hokkaido island and Aomori prefecture.

The agency lifted all tsunami advisories about an hour and half later.

The Japan Meteorological Agency said the tremor was 6.8 magnitude. An aftershock of magnitude 5.9 struck followed about two hours later.

The town of Otsuchi in Iwate prefecture, where more than 800 died in last year's tsunami, issued an evacuation order to all households along the coast as a precaution, said prefectural disaster management official Shinichi Motoyama. No damage or injury was reported from the quake so far, he said.

Iwate was heavily damaged by last year's earthquake and tsunami. Thousands of aftershocks have shaken the region since then, nearly all of them of minor or moderate strength.

The magnitude 9.0 earthquake and tsunami on March 11, 2011 left some 19,000 people dead or missing.

Japan marked the first anniversary of the disasters on Sunday, as the country still struggles to rebuild.
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