Gigantic cracks known as gullies are opening up in cities in Africa, swallowing up homes and businesses, sometimes in an instant, a study has found.

A new study published in Nature has revealed just how enormous this threat has become, focusing on the Democratic Republic of the Congo (DRC). Scientists mapped 26 cities across the country and found an astonishing 2,922 massive gullies, each one a scar across the urban landscape. These are not small erosions; they are immense chasms that can stretch hundreds of meters, tearing apart entire communities. And they are spreading.

Between 2004 and 2023, these gullies displaced nearly 118,600 people in the DRC alone. Entire families have been forced to leave homes passed down through generations, while the land beneath their feet collapses into voids. The danger is accelerating—today, 3.2 million people live in areas at risk of being swallowed, double the number from just over a decade ago.