An earthquake measuring 5.9 rattled eastern Japan, including Tokyo, early on Sunday, injuring at least 37 people, officials said.
There was no tsunami threat.
The Japan Meteorological Agency said the quake struck at a depth of 70km (42 miles), with its epicentre in southern Ibaraki prefecture. The US Geological Survey put the magnitude at 5.8.
At least 37 people were injured in five prefectures in the region: 15 in Tokyo, nine in Saitama, eight in Kanagawa, four in Chiba and one in Ibaraki, according to prefectural officials and the fire and disaster management agency.
Most of the injured were hurt when they fell down or hit themselves against furniture or doors as they were caught off guard by the quake while sleeping and got out of bed in a panic, officials said.
Among them was a woman in her 80s who fell off the bed and suffered a serious hip injury in Yokohama, in the Kanagawa prefecture, the Yomiuri newspaper reported.
A 23-year-old man told the Asahi newspaper that he felt a vertical jolt seconds after his earthquake alert went off when he was shopping in Tokyo’s eastern district of Taito.
He said he feared getting hit by merchandise that fell from shelves as the building shook.
The quake caused delays to express trains serving Tokyo and Narita Airport and other local trains serving northeastern regions, but Shinkansen bullet trains were running normally, their operator East Japan Railway Co said.
The government set up a task force to assess the extent of possible damage, prime minister Sanae Takaichi said on X.
The Japan Meteorological Agency urged the residents in the area to use caution against another possible moderate earthquake for about a week.
The tremor set off emergency quake alerts on mobile phones and also significantly shook Tokyo.
NHK public television showed traffic on roads in nearby cities, including Mito and Saitama, seemingly normal.
An underground water pipe ruptured in Tokyo’s eastern ward of Koto, with water pouring onto the road, NHK footage showed.
The pipe has since been repaired, and the leak stopped.
There were no reports of anomalies from about a dozen nuclear power plants and other facilities that handle nuclear materials, the Nuclear Regulation Authority said.
Last month, a magnitude 7.1 quake struck the Kumamoto area on Japan's southernmost island of Kyushu, killing 38 people and injuring 364.
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