Wire reporting: (AP, via The Boston Globe)

A magnitude 5.7 earthquake struck western Shizuoka Prefecture in central Japan at 1:04 a.m. Sunday local time (16:00 GMT Saturday), injuring more than 20 people, according to Japanese authorities cited by Kyodo and by Associated Press reports carried in U.S. outlets^1,2,5.

The Japan Meteorological Agency placed the quake about 40 kilometers (25 miles) below the surface; the U.S. Geological Survey listed it at magnitude 5.5, AP-sourced accounts said^1,2,5.

Kyodo, cited by Al Jazeera, said more than 20 people were injured in Aichi and Shizuoka prefectures and that no tsunami warning was issued¹. AP-sourced reports put the injured at least at 22, including people who fell on stairs while leaving buildings, according to local media^2,5,6.

Shaking was reported across a wide area near Aichi Prefecture, including Hamamatsu, Kyoto, Nara, Yamanashi and Gifu; the strongest shaking was in Aichi, and Tokyo did not feel the quake, those reports said^1,2,5.

Japanese television showed broken shop windows and books thrown from shelves, Al Jazeera and AP accounts said^1,2,6.

The meteorological agency warned of possible strong aftershocks in the coming week, especially the next two to three days^1,2,3. Agency official Ayataka Ebita told reporters to watch for mudslides, falling rocks and rainfall effects, and said no apparent change had been detected in the Nankai Trough^1,2,3.

Al Jazeera reported some local trains were suspended and that JR Central delayed Tokaido Shinkansen service between Shizuoka and Gifu-Hashima after safety checks, with trains running slower as a precaution¹. AP-sourced reports also described slower Shinkansen speeds in affected areas^2,5,6.

Smaller aftershocks were reported, AP accounts said^2,5.