There were no immediate reports of damage or injuries. Chichijima is 590 miles south of Tokyo. The region sometimes experiences such powerful quakes, but usually they are too deep to be strongly felt on land. Shigeji Sugimoto, a local official on Chichijima, said he felt Tuesday's earthquake but that it wasn't strong enough to have knocked items off shelves. There were no fears of a tsunami, a giant ocean wave caused by undersea disturbances such as volcanic activity or undersea earthquakes, the agency said.
Japan is one of the world's most earthquake-prone nations.
An earthquake of magnitude 7 is considered capable of causing widespread damage.