In the Croatian countryside, shortly before the new 2021, the earth began to behave very strangely. It would seem that out of nowhere in a garden in Mechenciani, a village 40 kilometers from the capital of Croatia, Zagreb, an almost perfect circular hole about 30 meters wide and 15 meters deep has formed.
In two Croatian villages, about a hundred perfectly round holes have formed in the ground. Scientists did not immediately understand why this happened.
A few weeks later, in Mechenchani and the neighboring village of Boroevichi, several dozen more such strange holes appeared on the ground. In total, more than 100 craters had formed in the two villages by March, IFL Science reports.
Fortunately, researchers have uncovered the core of this geological puzzle. At the end of last year in the central part of Croatia there was an earthquake with a magnitude of 6.4 points. The earthquake killed 7 people and injured 26. The tremors were felt throughout Croatia, as well as in neighboring Bosnia and Serbia.
Funnels are not the most frequent consequence of powerful seismic activity, but they do occur, especially in areas with hidden underground cavities. According to the BBC, this happened after the devastating earthquake near the Italian city of L'Aquila in 2009: two craters immediately formed on the roads in the old part of the city.
In Croatia, due to the Dinaric karst processes, there are dozens of caves underground, three of which are more than 1000 meters deep. These deep caves are formed by underground currents that slowly erode poorly soluble bedrock such as limestone. Over time, winding underground tunnels and caves can form.
Probably, the earthquake in Croatia literally destroyed the "ceilings" of these underground caves, creating dozens of sinkholes.
“Even without earthquakes, the earth above such voids would collapse and form depressions, as has sometimes happened in the past, but earthquakes accelerated and intensified these processes,” writes the Croatian Geological Institute.