{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

M Long A4.masswasting - Assignment 4 Due end of day Jan 14...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Assignment 4. Due end of day Jan. 14. 1. A small amount of water will increase slope stability; the surface tension of a thin film of water holds the particles together and secures the subsoil. This allows the soil to resist erosion better than if it were dry. Larger amounts of water can decrease slope stability in many ways. When water seeping into the earth reaches an impenetrable layer, it accumulates and forces the grains of soil to separate., lubricating the ground and making it unstable (7). Water also adds weight to the soil which will decrease slope stability (13). 2. Among the many factors that can lead to mass wasting are a change in slope angle, weakening of material by weathering and erosion, increased soil moisture, changes in vegetation cover, reduction of roots holding the soil to bedrock, earthquakes and an increase in weight (1). Personally, I would imagine that the most important factors are sudden increases in soil moisture or seismic events. Many of the other changes evolve over time and steadily increase the probability of a mass wasting event whereas a period of heavy rain or earthquake seem like a near guarantee that areas of greater instability will collapse. After watching the video of the Malaysian landslide, my best guess is that tin mining in the region weakened the structure of the land and may have also increased the slope angle. Jarring from each collapse may have also helped triggered subsequent collapses (8). 3. A fall is a mass movement that involves the free fall of detached individual pieces. In contrast, a slide occurs whenever material remains coherent and moves along a well-defined surface. Flow is a type of movement that occurs when material moves down slope as a viscous fluid. Unlike falls and slides, most flows are saturated with water. A slump refers to downward sliding or material moving along a curved (usually concave upward or outward) surface or rupture. The term avalanche describes the most rapid type of mass movement while creep describes very slow movement usually measured in centimeters per year (9). 4. Granular flows contain between 0 and 20% water. A slurry flow is a sediment flow that contains between about 20 and 40% water. A higher water content is considered a normal water flow. For example, as the water content increases above about 40%, slurry flows are considered streams.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}