Authorities warned people in the greater Tokyo area that more tremors are possible in the days ahead after a magnitude 5.9 earthquake struck east of the capital late Thursday.
The quake did not trigger a tsunami or cause major damage, but more than 20 people were injured.
Tsukada Shinya of the Japan Meteorological Agency said, "Based on past experience, a quake with a similar intensity occurred within about a week of a major earthquake in 10 to 20 percent of past cases. Please stay alert for the next week or so, if you are in an area where there was a strong tremor. Major quakes in particular tend to strike within a couple days after the first one."
The quake occurred at 10:41 p.m., Japan time, as many people were heading to sleep. Its focus was east of Tokyo, at a depth of 75 kilometers.
In Tokyo and Saitama prefectures, the quake registered an intensity of five-plus on Japan's seismic scale of zero to seven. People throughout the area felt the jolt.
Prime Minister Kishida Fumio set up a task force at his office to oversee the response.
The earthquake disrupted public transportation throughout the area. One train in Tokyo's Adachi Ward derailed after making an emergency stop, injuring at least three people.
Railway officials say service on bullet train lines was suspended but later resumed. Some local lines were also halted, forcing people to hunt for taxis.
A wall of a building in northern Tokyo collapsed. Police have asked people there, and elsewhere, to stay away from any dangerous areas.
A fire broke out in a building outside of the capital, sending flames and smoke into the air as emergency crews rushed in.
Pipes ruptured in several neighborhoods, which sent water gushing onto sidewalks and toward nearby houses.
Authorities have not detected any abnormalities at nuclear-related facilities in Ibaraki and Kanagawa prefectures.
Officials are warning residents to be cautious of structural damage that may have already occurred.