The Japan Meteorological Agency warns that more earthquakes of a similar intensity are possible over the next week or so, following the strong tremor that hit Tokyo and nearby areas on Thursday night.
Agency officials say the magnitude 5.9 quake occurred at 10:41 p.m., Japan Time. The quake's focus was in northwestern Chiba Prefecture, neighboring Tokyo, at a depth of 75 kilometers. The quake did not trigger a tsunami.
The quake registered an intensity of five plus on Japan's seismic scale of zero to seven in Tokyo's Adachi Ward, as well as Kawaguchi City and Miyashiro Town, both in Saitama Prefecture.
The officials say an intensity of five plus was recorded in Tokyo's 23 wards and Saitama for the first time since a magnitude 9 earthquake struck northeastern Japan in March 2011.
They say Thursday's quake caused long-period ground motion that swayed high-rise buildings in Tokyo and Chiba Prefecture.
The agency says that shortly after 5:00 a.m. on Friday, Japan Time, a magnitude 3.6 earthquake occurred in the area close to the focus of Thursday's quake.