Landslides occur when masses of earth, rock or debris move down
a slope. Landslides can happen without warning and can range in size with some of the biggest ones sliding at avalanche speeds. Earthquakes, significant rainfall, and human modifications of land are some of the most common causes of landslides. Landslides can travel many miles from their source and grow in size as they accumulate trees, cars, rocks and other debris. Bellevue is in a relatively hilly region and experiences significant amounts of rainfall which makes it susceptible to landslides. Rainfall can turn the earth on slopes into a flowing mud-like consistency which can move rapidly down a slope.
The recent Oso Landslide near Bellevue is a prime example of the damage that a large landslide can do. The Oso Landslide was responsible for 43 deaths, 49 structures destroyed and covered approximately a 1 square mile area. Landslides can happen extremely quickly and without warning but there are some ways that an individual can attempt to recognize signs of landslide forming. Bulging ground at the bottom of a slope, widening cracks develop on the ground or on paved areas, and patterns of rainwater drainage on hills or small slides can all indicate if a landslide is forming. Landslides can also be avoided be being aware proper land-use procedures.
Avoiding building on steep slopes, hill edges, drainage routes, and erosion areas can greatly contribute to decreasing the likelihood of landslides occurring.