Strong tremors injure eight as central Japan returns to school

TOKYO—A series of powerful tremors Monday rattled a central Japanese region still reeling from last month’s earthquake, slight­ly injuring eight people just as the last schools shut by the tragedy reopened.

Six tremors, with the strongest measuring 5.9 on the Richter scale and felt in Tokyo, struck within three hours starting at 11:15 a.m. (0215 GMT) in Niigata prefecture, the Meteorological Agency said.