TOKYO - Tsunami waves have been observed off Iwate and Aomori prefectures in the Pacific Ocean after a 7.5-magnitude earthquake struck off the Sanriku coast in northeastern Japan on Monday afternoon.

Kuji port in Iwate prefecture recorded an 80-cm wave.

No abnormalities have been reported so far at nuclear plants in the affected prefectures of Aomori and Miyagi, and no new issues have been identified at the Fukushima Daiichi and Daini nuclear plants, according to their operators.

The temblor occurred at 4:53 pm local time at a depth of 10 km, measuring upper 5 on Japan's seismic scale of 7 in the hardest-hit areas in Aomori prefecture, said the Japan Meteorological Agency.

The quake's epicenter was located at a latitude of 39.8 degrees north and a longitude of 143.2 degrees east.

People in quake-affected areas have been urged to seek higher ground.