15.2 What causes mass movements?

Text and Images from Slide

Images of pieces of wood with a brick on each. The wooden boards are raised at angles until the brick slides.

Fig 15.11

Under the conditions below, a brick on a board will slide if tilted far enough. What does this mean? 1) Increasing slope favors motion or slope instability. Next, we may sand the board and find it moves more easily. 2) Smoother surfaces favor motion and slope instability, and if we wet the board, it moves easier still; 3) the presence of

water favors motion and slope instability.

So slope angle, smoothness of surface, and presence of water all seem to enhance the tendency to slide down a slope.

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Text and Images from Slide