More than a dozen earthquakes, one of them magnitude 6.2, rocked a volcanic island south of Tokyo Wednesday, the national meteorological agency said.
There were no immediate reports of injuries or property damage from any of the quakes and no risk of a tsunami, the agency said.
The biggest tremor, with its epicentre located near Miyake Island some 180 kilometres (110 miles) south of Tokyo, was registered at around 5:57 pm (0857 GMT), the Japan Meteorological Agency said.
"There may be slight changes in the level of sea along Japan's coast but there is no fear of damage resulting from this quake," the agency said.
There had been 13 minor quakes near the island -- an active volcano -- since 10:15 am (0115 GMT) Wednesday.
A small earthquake was also registered four minutes after the 6.2-magnitude tremor, the agency said.
The volcano erupted in 2000, forcing all 3,800 islanders to evacuate. Many of them have since returned to the island.