Why do landslides happen?

February 1, 2022 – A landslide is made of mud and other earth materials that fall down a slope, usually after a period of heavy rain. When buildings balance on soils that cannot effectively capture and react to precipitation, landslides may occur. The weight of the water and the steep incline push the mud and dirt downhill. The Soil Science Society of America’s (SSSA) February 1^st Soils Matter blog takes a look at the factors that contribute to these disruptive events.

1. The increasing rate of intense storms, of course, has made past calculations somewhat unpredictable now. Soil that once was able to absorb rainfall may now be ill equipped for sudden, heavy surges of water.
2. Fires such as those in California, can change the properties of the topsoil, making it less likely to absorb water.
3. Gravity also plays a major role in landslides. This natural force is always pulling for things to “fall downhill.” That’s why engineers look at the steepness of the slope and accommodate for that in their planning.
4. Erosion also affects the stability of the slope, and continuously changes the physics of a slope. Imagine ocean waves or rivers cutting into the edge of a slope, pulling critical base material away. Like a giant game of Jenga, with the right factors, a landslide can happen.

Landslides can happen in all 50 states, but there are certain places where landslides are more prone to happen. For example, on the West Coast, states like California, Washington, and Oregon see more landslides than other states because of their hilly terrain. Lands altered by humans or wildfire are also more at risk for landslides. To learn more about landslides, visit the Soils Matter blog https://soilsmatter.wordpress.com/2022/02/01/why-do-landslides-happen/. Watch SSSA’s video Soils Support Buildings and Infrastructure, for more information.

Follow SSSA on Facebook at https://www.facebook.com/SSSA.soils, Twitter at SSSA_Soils. SSSA has soils information on www.soils.org/discover-soils, for teachers at www.soils4teachers.org, and for students through 12^th grade, www.soils4kids.org.

The Soil Science Society of America (SSSA) is a progressive international scientific society that fosters the transfer of knowledge and practices to sustain global soils. Based in Madison, WI, and founded in 1936, SSSA is the professional home for 6,000+ members and 1,000+ certified professionals dedicated to advancing the field of soil science. The Society provides information about soils in relation to crop production, environmental quality, ecosystem sustainability, bioremediation, waste management, recycling, and wise land use.