EOSC 110 Chapter Notes - Chapter 15: Mass Wasting, Mudflow, Silt
Document Summary
Factors: (1) steep slopes (2) great relief (3) water and ice add weights and make it more fluid (4) loose rock and debris (5) no plants with roots to anchor loose material on the slope (6) earthquakes. Water: when soil is saturated with water, it becomes less viscous and is more likely to flow downslope. That also adds shear force, but the force is less important than the reduction in shear strength. Due to the increase in pore pressure forcing soil grans apart. However, small amount of water helps prevent downslope movement. Little water forms thin films around each grain. Mudflows always have high ratios of water to earth. Triggers: (1) earthquakes (2) heavy rainfall, increases pore pressure in material. Pressure (3) construction, the extra weight of buildings on a hillside can cause a landslide. By three standards: (1) rate of movement, (2) type of material, whether descending mass started as bedrock, or as unconsolidated material.
