Aerial photo taken on Jan. 28, 2021 shows a sinkhole in Mecencani, Croatia. 51 sinkholes have appeared since a 6.4-magnitude earthquake hit central Croatia in late December of 2020.Photo:Xinhua

Aerial photo taken on Jan. 28, 2021 shows a sinkhole in Mecencani, Croatia. 51 sinkholes have appeared since a 6.4-magnitude earthquake hit central Croatia in late December of 2020.Photo:Xinhua

Aerial photo taken on Jan. 28, 2021 shows a sinkhole in Mecencani, Croatia. 51 sinkholes have appeared since a 6.4-magnitude earthquake hit central Croatia in late December of 2020.Photo:Xinhua

Aerial photo taken on Jan. 28, 2021 shows a sinkhole in Mecencani, Croatia. 51 sinkholes have appeared since a 6.4-magnitude earthquake hit central Croatia in late December of 2020.Photo:Xinhua