TOKYO—A powerful earthquake struck off the northern Japanese coast early Thursday, injuring at least 91 people, triggering landslides and cutting power to thousands of people, officials said.

Japan’s Meteorological Agency said there was no danger of a tsunami from the temblor, which had a preliminary magnitude of 6.8. It struck shortly after midnight about 65 miles underground and centered just off the coast of Iwate, 280 miles northeast of Tokyo.

The 91 people injured were mainly suffering from cuts and bruises from broken glasses and falling objects and none of the injuries was life threatening, said National Police Agency official on condition of anonymity, citing department policy.

The earthquake caused strong shaking of up to 40 seconds in large parts of northern Japan, official said.

The earthquake also triggered landslides at several locations, the police agency official said.