Impact and Response
Japanese television showed shattered shop windows and shards of glass scattered across streets. A bookstore was left with mounds of books that had fallen from the shelves.
Some of the injured had fallen on the stairs as they tried to flee, the Associated Press news agency reported.
No tsunami warning was issued, Kyodo reported.
The meteorological agency warned people to be ready for possible strong quakes in the coming week, especially the next two to three days.
"Please be on the lookout for mudslides, falling rocks and the possible effects from rainfall," agency official Ayataka Ebita told reporters.
He said no apparent change had been detected so far in the Nankai Trough, an underwater ocean trench where two major tectonic plates meet under parts of Japan, where scientists say a megaquake could occur.
Some local train services were suspended, while the Shinkansen bullet trains were running at slower speeds in affected areas as a precautionary measure.
Trains on the Tokaido Shinkansen line, which connects Tokyo and Osaka, were delayed between Shizuoka and Gifu-Hashima stations after safety checks, rail operator JR Central said.