A sinkhole measuring about two football fields or 200 meters long and six stories or 20 meters deep has opened up near the city of Rotorua in New Zealand's North Island.
The sinkhole, which appeared after a prolonged period of heavy rains, has exposed 60,000-year-old volcanic soil and could get bigger, according to volcanologist Brad Scott.
Upon examining the feature, Scott concluded that there has been an erosion of limestone in the area over the past 100 years. Scott told TVNZ that the deposit was covered by ten to 12 meters of sediment, left over from ancient lakes and three meters of volcanic ash.
The volcano is reportedly dormant.
Nine similar environment features have appeared in the region – known as Earthquake Flat – over the past few years. New Zealand sits on several major fault lines that span the length of the country. In 2017, a massive sinkhole opened up in New Lynn, a suburb of Auckland, some 143 miles from Rotorua.
According to the U.S. Geological Survey, sinkholes open up when groundwater does not drain from the surface and dissolves underlying rocks, collapsing the area.
Sinkholes can also be caused by human land development – construction or the pumping of groundwater can result in destabilization.
Mexico, Belize, parts of Italy, Slovenia, Croatia and Russia are also prone to sinkholes, according to the Nat Geo.
China has the world's largest cluster of sinkholes.