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How does erosion at the base of a slope contribute to landslides?
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landslide
This 1995 landslide at La Conchita, a coastal town in California, swept away a hillside road and destroyed a number of houses.
Erosion at the base of a slope contributes to landslides by causing the oversteepening of the slope.1
In geological terms, landslides occur when the gravitational and other shear stresses acting within a slope exceed the shear strength—the material's resistance to shearing. Natural erosion, such as that caused by rivers or coastal waves, removes material from the base of a slope, which increases the internal shear stress and destabilizes the slope's geometry. Once these stresses surpass the shear strength of the rock, debris, or soil, the slope becomes prone to failure, resulting in a landslide.21