Mass Wasting Lecture-18

A set of flashcards to help review key terms and concepts related to mass wasting and landslides.

Mass Wasting

Downslope movement of rock or soil as a more or less coherent mass.

Landslide

Colloquial term for any large mass movement of the ground.

Fatal Mass Wasting Events (2004-2010)

Records showed 80,058 deaths from mass wasting events.

Seismic Landslides

Landslides triggered by earthquakes, totaling 47,736 deaths between 2004 and 2010.

Oso Mudslide

A significant landslide in Washington in March 2014 that caused 43 fatalities.

Slope Failure Factors

Gravity, landscape slope, cohesion, water content, and external triggers influence slope stability.

Angle of Repose

The maximum gravitationally stable angle of a hillslope.

Cohesion

Forces that bind particles in a rock together, influencing slope stability.

Water Content

Influences slope stability; too much can cause instability through increased pore pressure.

Types of Mass Movements

Includes slides, slumps, flows, and falls with varying speeds and characteristics.

Debris Flow

Rapid failure of soil or loose materials that behaves like a fluid.

Rotational Slide/Slump

Failure occurs along a plane of weakness with multiple rotated blocks.

External Triggers of Hillslope Failure

Events like earthquakes, rainfall, and human actions that can initiate landslides.

Stability of Loose Materials

Stable angles of repose for different materials: loose sand (30-35°) and saturated sand (<10°).

Human Involvement

Anthropogenic activities like logging that can contribute to slope failure.

Cohesion/Rock Strength

Refers to the strength of rock and soil that affects slope stability.

Topple

A type of mass movement where material falls from a steep slope.

Landform Examples

Features like river bank erosion and over-steepened slopes can indicate potential landslide hazards.

Geology's Role

Tectonically active areas with soft geology are more susceptible to mass wasting events.

Historical Landslide Data

Data that reveals the patterns and occurrences of fatal landslides over time.

Landslide Mitigation

Measures taken to reduce the impact and frequency of landslides.