Landslides in El Salvador

Even before hurricane Ida slammed into El Salvador, three days of rain triggered deadly landslides that killed more than a hundred people. Heavy rain sets off landslides, but it may not be a matter of just washing loose dirt downhill. If that were the case, we would see only mud in the streets. Instead there were debris flows, movements of material that included boulders as well as fine particles. Too much rain disrupts the ground as a whole by raising the pore pressure of water underground—it weakens the soil by forcing it upward and loosening its hold on the ground. Thus a whole hillside can give way, quickly turning into a fluid mass and wiping out everything in its path.

More on landslides
Picture gallery of landslides