Japan’s weather agency says a strong earthquake with a preliminary magnitude of 6.1 struck off the northern Japanese coast. There were no immediate reports of damage or injuries.

The Meteorological Agency says there was no danger of a tsunami, or seismic waves, from the 8:30 p.m. quake on Monday, which occurred about 20 miles below the ocean’s surface off the coast of Fukushima.

Japan is one of the world’s most earthquake-prone countries.