Landslide, mudslide, debris flow–it doesn't matter what you call it, the outcome is the same: normally stable and stationary soil gets a bad case of wanderlust. In most cases, slides are triggered when too much water saturates a steep slope or when an earthquake shakes the ground loose. This can occur almost anywhere, but Central America–with its precipitous hills, frequent heavy rainstorms and unstable volcanic soil–is probably the number one hotspot. Ed Harp, a landslide geologist with the U.S. Geological Survey (USGS), describes the local soil as "like glass shards that interlock with each other." This cohesion, he explains, enables the soil to adhere to near-vertical slopes without sliding off.