More than a dozen dams have failed this week in South Carolina amid catastrophic flooding that has destroyed homes and businesses and left more than a dozen people dead. Authorities are warning that additional failures are possible. The ultimate cause is too much rainfall over a short period, but the disaster also points to longer-term problems in infrastructure that are putting thousands of people at risk around the world.

The structures that have failed in South Carolina are like the vast majority of dams around the world: they are made of earth.

“When people think of a dam they often think of a giant concrete structure, like Hoover or Coulee Dam, but the vast majority are made of earthen materials,” says