Nine fairly strong earthquakes, all registering 4 on the 7-point Japanese intensity scale, jolted the islands of Niijima, Kozu, and Miyake in the Izu chain Monday, the Meteorological Agency said.
There were no immediate reports of casualties or damage caused by the quakes, which struck between 4:42 a.m. and 1:00 p.m.
The focus of the strongest quake, at 5:03 a.m., which had a magnitude of 5.4, was located about 10 km below the seabed off Miyake, a small volcanic island some 180 km south of Tokyo.