A cluster of around 100 sinkholes has opened up across farmland in central Croatia, some of them just metres from homes, in the aftermath of a deadly quake that rocked the area in December.
The holes started appearing days after a 6.4 magnitude quake struck killing seven people and tearing down hundreds of buildings around the town of Petrinja on December 29.
With the largest opening measuring 25m across, the sinkholes pose yet another danger for communities still rebuilding from the disaster.
The sudden depressions are triggered when groundwater erodes the bedrock below to a point where it can no longer support the soil above.
A chief engineer at Croatia’s national geological survey Stjepan Terzic told AFP that while sinkholes are a normal phenomenon, the high concentration of them “in such a small location” is unusual.
The quake’s aftershocks – which are still shaking the area – caused the normally slow formation of sinkholes to accelerate dramatically.
“Thus in a short period of time numerous holes have emerged for which, in normal conditions, decades if not longer periods would be needed.”
The holes, many of which look like small round ponds as they have filled with emerald groundwater, have emerged in farm plots around the villages of Mecencani and Borojevici.
Experts have called for additional caution in the coming weeks as groundwater levels are expected to rise in spring, threatening further collapse of the terrain.