Two earthquakes with preliminary magnitudes of 4.4 and 4.2 struck Ibaraki Prefecture early Thursday, the Meteorological Agency said.
The 2:13 a.m. and 4:46 a.m. temblors both originated in the northern part of the prefecture at a depth of about 10 km, registering 4 on the Japanese seismic intensity scale to 7 in Hitachi, according to the agency.
The quakes were also felt to a lesser extent in neighboring Fukushima Prefecture.