[Rockhounds] The Croatian village where the land became 'Swiss cheese'

[Kreigh Tomaszewski]

It happened suddenly and without warning. Where there should have been the
emerging first shoots of potato seedlings behind the orchard in Nikola
Borojević's spacious garden, there was now huge hole. Measuring 30m (98ft)
wide and 15m (49ft) deep, it quickly filled with water. And it wasn't the
only one.

Within the space of a few weeks, dozens of similar holes had opened up
<http://www.geologia-croatica.hr/index.php/GC/article/view/1057> around the
village of Mečenčani and neighbouring Borojovići in north-east Croatia. The
one outside Borojević's home in Mečenčani appeared on 5 January, just six
days after a 6.4 magnitude earthquake struck the area around the nearby
city of Petrinja. It was the strongest earthquake to have hit Croatia for
more than four decades, killing seven people and destroying thousands of
homes.

While landslides and sinkholes are known to be triggered by earthquakes,
along with other strange geological phenomena such as liquefactions – where
the solid ground begins to behave like a liquid – the sheer number of holes
<https://www.bbc.com/news/av/world-europe-56359244> appearing around the
two villages surprised and baffled experts. A month after the earthquake,
there were almost 100 sinkholes
<https://www.mdpi.com/2072-4292/13/6/1095/htm#B16-remotesensing-13-01095>
spread
over a 10 sq km (3.8 sq miles) area
<https://crocee.grad.hr/event/1/contributions/193/>, with new ones opening
every week.

The hole in Borojević's garden is now the largest in the area. When it
first appeared it was 10m (33ft) wide, but started to grow almost
immediately.

"My wife was in the house the whole morning, looking occasionally through
the window," says Borojević. "Around 2pm she noticed something strange in
the garden. We went outside and there was this huge hole in our orchard."
Over the following three months, the hole tripled in size.

But the Borojevićs were lucky. Other sinkholes in the area opened up just a
few metres from the doorsteps of people's homes and one appeared beneath a
house, prompting officials to consider evacuating both villages. Others
appeared in the surrounding woods and agricultural fields, where one of
them, according to some local rumours, almost swallowed the local farmer
and his tractor.


https://www.bbc.com/future/article/20210702-how-an-earthquake-created-a-village-full-of-sinkholes