A strong earthquake hit Japan’s northern coast near the nuclear power plant that was crippled in the 2011 earthquake and tsunami. The earthquake early Saturday triggered a small tsunami and prompted towns across the northern coast to issue evacuation advisories.

The quake, initially measured at magnitude 6.8, struck at 4:22 a.m. Saturday at the epicenter (9:22 a.m. Friday in Hawaii), was centered 81 miles east of Iwaki and 176 miles east-northeast of Tokyo, at a depth of 8.2 miles, according to the U.S. Geological Survey.

The quake shook buildings in Tokyo. Japan’s Fire and Disaster Management Agency said there were no reports of damages or injuries.

Towns devastated by the tsunami three years ago, including Rikuzentakata, Higashi Matsushima and Otsuchi, issued evacuation advisories to thousands of households along the northern coast, along with schools and community centers.

An 8-inch tsunami reached the coast of Ishinomaki Ayukawa and Ofunato, about 50 minutes after the quake. Smaller waves were observed at several other locations along the coast.

Changes to the shoreline, however, were not visible on television footage from Japan’s NHK public broadcaster.

There is no threat to Hawaii, according to the Pacific Tsunami Warning Center on Oahu.

"No destructive widespread tsunami threat exists based on historical earthquake and tsunami data. However, earthquakes of this size sometimes generate local tsunamis that can be destructive along coasts located within a hundred kilometers of the earthquake epicenter," the PTWC bulletin said.

Fukushima Daiichi and two other nuclear power plants, along with other nuclear facilities along the coast, found no abnormalities, and their reactors and fuel storage pools are being cooled safely, according to Japan’s Nuclear Regulation Authority.

Tokyo Electric Power Co., which operates the Fukushima Daiichi plant, has instructed plant workers on night duty along the coast to retreat to higher ground.

The 2011 disaster killed about 19,000 people. That disaster also triggered multiple meltdowns at the Fukushima plant. More than 100,000 people are still unable to go home due to fear of radiation contamination from the plant.