An earthquake with a preliminary magnitude of 5.0 hit Niigata Prefecture on Sunday, injuring at least two people, officials said.
The two men sustained minor injuries to their arms from a broken window in the city of Kashiwazaki.
According to the Meteorological Agency, the quake occurred at 11:29 a.m. with the focus in the prefecture's Chuetsu region. No tsunami warning was issued.
The temblor registered an upper 5 on the Japanese seismic intensity scale of 7 in Nagaoka, and a lower 5 in Ojiya, the agency said.
Intensity 4 or lower tremors were logged in a wide area in central and northeastern Japan, including the Hokuriku, Kanto, Tohoku and Chubu regions.
East Japan Railway Co. said bullet trains on the Joetsu Shinkansen Line were briefly halted, but it found no irregularities and soon resumed services.
Tokyo Electric Power Co. said it hadn't not found any irregularities in its Kashiwazaki-Kariwa nuclear power plant in Niigata Prefecture. The plant continued operating.
The Chuetsu region has been rattled by numerous quakes since a magnitude-6.8 earthquake last Oct. 23 that claimed the lives of 40 people.
The government set up a crisis management center in the Prime Minister's Official Residence minutes after the quake to collect information from local authorities and related ministries.
Sunday's quake, however, was probably not related to the Oct. 23 one, the agency said, citing the differences in their locations.
