More than 9,000 people were in evacuation centres early Wednesday after a major quake hit southwestern Japan, the government said.

"We have received reports of seven people with serious injuries and 29 with minor injuries. Furthermore, as of 7:00 am today (2200 GMT Tuesday), 9,186 people have sought refuge in 506 evacuation centres across five prefectures, including Kumamoto and Fukuoka," government spokesman Minoru Kihara said a day after the quake that killed at least 13 people.