Landslides and Mass Wasting: Lecture 7

These flashcards cover key vocabulary and concepts related to landslides and mass wasting, exploring causes, effects, stability factors, and mitigation strategies.

Mass Wasting

The downslope movement of rocks, sediment, soil, and ice driven by gravity.

Slope Stability

The ability of a slope to remain intact or resist mass wasting.

Relief

The difference in elevation between locations on the land surface.

Critical Thinking

A process of evaluating and analyzing information to form a judgment.

Gentle Slope

A slope with angles less than 5°.

Moderate Slope

A slope with angles between 5° and 35°.

Steep Slope

A slope with angles greater than 35°.

Vertical Slope

A slope with an angle of 90°.

Slope Shapes

Determined by the strength of material, climate, and how the slope formed.

U-Shaped Glacial Valley

A valley shaped by glacial erosion, characterized by a U-shaped cross-section.

V-Shaped River Valley

A valley formed by river erosion, characterized by a V-shaped cross-section.

Normal Stress (σn)

Force perpendicular to a surface.

Downslope Shear Stress (σd)

Force parallel to a surface causing movement down a slope.

Resistance Stress (σr)

Friction or resistance that opposes motion.

Safety Factor

The ratio of resistance stress to downslope shear stress (σr ÷ σd).

Joints

Cracks in rocks that can lead to instability and movement.

Friction

Small protrusions that act to anchor rocks and resist movement.

Cohesion

The forces that bind sediment grains together.

Angle of Repose

The maximum angle at which loose material can remain stable.

Planes of Weakness

Structural features in rocks that influence stability, such as joints and bedding planes.

Creep

Slow, gradual movement of regolith caused by repeated expansion and contraction.

Solifluction

A form of creep in areas with permafrost, where thawed layers slide down.

Slump

A type of mass wasting where rocks and regolith move downward while remaining mostly coherent.

Mudflow

A non-coherent flow of mud, typically saturated with water.

Debris Flow

A flow of water and large rocks, which can be fast-moving and destructive.

Rockslide

The rapid downslope movement of rock and debris without water.

Liquefaction

A process where saturated sediment loses strength and behaves like a liquid under stress.

Undercutting

The removal of material from the base of a slope, increasing instability.

Vegetation

Roots that help bind soil and prevent erosion.

Wet/Dry Cycle

Natural cycling between wet and dry conditions that leads to ground movement.

Critical Thinking 1

Analyzing how relief forms.

Mass Movement

The movement of surface materials down slopes, affected by gravity.

Seismic Activity

Earthquakes or vibrations that can trigger landslides.

Hydrologic Conditions

Water content and saturation level affecting slope stability.

Trapped Lake

A lake formed by landslide debris blocking a valley.

Risk Mitigation

Strategies implemented to minimize the risk of landslides.

Hazard Mapping

A technique used to identify areas at risk for landslides.

Engineering Solutions

Structural methods to stabilize slopes and prevent landslides.

Drainage Systems

Methods used to reduce water pressure on slopes.

Retaining Walls

Walls built to hold back soil and prevent slope failure.

Fencing

Structures to prevent stones and debris from spilling onto roads.

Rock Bolting

An engineering technique using bolts to stabilize slopes.

Research in Landslide Areas

The study of past landslides to inform future risk assessments.

Slope Orientation

The direction of a slope which affects its weathering and stability.

Debris Flow Characteristics

Composed of mud and larger fragments, highly mobile and capable of destruction.

Geological Surveys

Assessments that identify geological hazards and slope stability.

Natural Erosion

The process by which natural forces wear away the earth, contributing to slope instability.

Cracked Infrastructure

Signs of instability such as cracked roads or buildings indicating slope problems.

Preventive Measures

Actions taken to avert future landslide events, including vegetation planting.