TOKYO -- Japan's weather agency issued a tsunami advisory for northern Japan's Pacific coast after a magnitude 6.7 earthquake struck off Aomori Prefecture on Friday.

According to the Japan Meteorological Agency (JMA), the temblor occurred at 11:44 am local time off Aomori's Pacific coast at a depth of 20 km, measuring 4 on Japan's seismic scale of 7 in the hardest-hit areas.

The JMA, which revised the magnitude of the quake up from 6.5, issued the tsunami advisory for the coastal areas of Hokkaido, Aomori, Iwate and Miyagi prefectures along the Pacific coast, with waves up to 1 meter expected.

The quake's epicenter was at a latitude of 40.9 degrees north and a longitude of 143.0 degrees east.

On late Monday night, a 7.5-magnitude earthquake struck the same region, measuring upper 6 on Japan's seismic scale of 7 in parts of Aomori, prompting the JMA to issue tsunami warnings for Iwate Prefecture and parts of Hokkaido and Aomori prefectures.