Landslides Flashcards
Landslide:
The movement of rock, earth, or debris down a slope due to gravity.
Mass Movement:
The downslope movement of rock, soil, and debris under the influence of gravity.
Slope Stability:
The resistance of a slope to failure or collapse.
Safety Factor:
A measure of slope stability that compares the forces resisting movement to the forces driving movement.
Types of Landslides:
Different classifications of landslides based on their movement characteristics, such as falls, slides, and flows.
Oso Landslide Event:
A specific landslide event that occurred in Washington State in 2014, known for its devastating impact.
Debris Flow:
A type of landslide characterized by the rapid movement of a mixture of rock, soil, and water down a slope.
What factors influence the speed of flows?
The speed of flows depends on the water content, type of materials, and the nature of the movement.
What causes creep?
Creep occurs due to the swelling and shrinking of the uppermost layer of the Earth’s surface.
What are mudflows?
Mudflows are fast-moving flows of mud, debris, and water.
What are lahars?
Lahars are volcanic mudflows, often triggered by volcanic eruptions.
What is the Bingham Canyon Mine known for?
The Bingham Canyon Mine is the largest open-pit copper mine in the United States.
What methods can be used to prevent mass movement?
Methods to prevent mass movement include building retaining walls, using rock bolts, controlling water, terracing, covering steep slopes, and reducing slope materials.
What is the purpose of retaining walls?
Retaining walls are built to hold back earth and prevent it from sliding or eroding.
What are rock bolts?
Rock bolts are long, anchored rods used to stabilize rock structures and prevent rockfall.
What is terracing?
Terracing involves creating steps on steep slopes to reduce the slope gradient and prevent erosion.
What are protective structures?
Protective structures are designed to shield areas from potential hazards, such as landslides or floods, by redirecting or containing the flow of materials.
Why is mass movement considered a costly type of natural hazard?
Mass movements can cause damage to living things and buildings, resulting in catastrophic losses.
How is the Safety Factor (SF) calculated to evaluate slope stability?
SF = Resisting forces / Driving forces. A SF > 1 indicates a safe or stable slope, while SF < 1 indicates an unsafe or unstable slope.
How does water affect slope stability?
Water can both increase and decrease slope strength. Small amounts increase surface tension between grains, while large amounts lubricate the grains, allowing them to flow more easily.
Why are slope failures common after forest fires?
Vegetation stabilizes slopes by slowing the removal of excess water and providing an effective stapling mechanism through roots. Removing vegetation can greatly increase the risk of slope failure.
How can earthquakes trigger mass movements?
Ground vibrations from earthquakes can decrease material friction and cause saturated sediments to liquefy, leading to mass movements.