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USGS CMG InfoBank: Causes of Mass Wasting

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Comment: 04:13 - 05:01 (00:48)
Source: Annenberg/CPB Resources - Earth Revealed - 16. Mass Wasting
Keywords: construction, road, building, slope, water, soil, rock, pore space, "surface tension", "mass wasting", stability, over-steepening

Our transcription: When bulldozers cut into hills to create home sites or roads, their stability is sometimes greatly reduced.
Over-steepening is not the only problem, however.
The heavy weight of a building itself can diminish the stability of an underlying slope as can the presence of water.
As water seeps into the ground, it begins to fill up pore spaces.
The surface tension of water actually helps to hold fragments of rock and soil together, but if a lot of water is present, it completely fills the pores and forces the fragments apart, thus weakening the slope.
Whether it comes from a sprinkler, a septic system, or a rainstorm, an excessive amount of water in the soil can trigger a mass wasting event.

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Page Last Modified: Thu Oct 31 04:26:57 PDT 2013  (chd)