Japan has issued a warning of possible recurring earthquakes after a pre-dawn tremor on Thursday injured several people in the country's east.
A magnitude 5.2 quake jolted the eastern Chiba province and parts of capital Tokyo at around 4:16 a.m. (1916GMT Wednesday), the Japan Meteorological Agency said in a statement.
The agency warned that "quakes on a similar scale could occur for about a week" and there could be a "risk of falling rocks and landslides."
At least four people were injured in Chiba and Kanagawa provinces, according to the Kyodo News Agency.
The reports said some rail services in the affected region were either canceled or delayed.
