Japan’s northeastern coast was hit Friday by a 6.5-magnitude earthquake, triggering a brief tsunami advisory for waves of up to 20 inches.

The earthquake, which struck at 2:36 p.m. local time, was centered 70 miles off the coast of Fukushima and 175 miles northeast of Tokyo. There were no immediate reports of damage or injuries, and the Tokyo Electric Power Co. said that its disaster-hit Fukushima Daiichi nuclear plant was experiencing no further problems.

The tsunami advisory was issued for both Fukushima and Miyagi prefectures, two of the areas hardest hit March 11 by a 9.0-magnitude earthquake and resulting tsunami.

There were no immediate reports of high waves caused by Friday’s earthquake.

This earthquake was the biggest to hit Japan in more than a month. But the country’s northeastern coast has been the site of more than 1,000 aftershocks of magnitude 4.0 or higher since March.

At the nuclear plant, some employees were temporarily evacuated immediately after the earthquake. Bullet trains in the region also briefly stopped running.