19- Landslide Hazard

Question 1

Landslide definition

Answer 1

Mass movement of material, such as rock, earth, debris or mud down a slope.
Can happen suddenly or more slowly over long periods of time

When the force of gravity acting on a slope exceeds the resisting forces of a slope, then the slope fails and a landslide occurs

Question 2

Rock falls

Answer 2

Occur on steep slops with loose rock that periodically detach from a surface on which little or no shear/sliding takes place

Question 3

Slides

Answer 3

Involve large volumes of rock or soil moving as an initially coherent mass on a sliding surface

Question 4

Rotational slides

Answer 4

Soil or weak rock collapses along a curved rupture surface that forms due to shear forces in the slope exceeding the shear strength of solid/rocks

Question 5

Translational slide

Answer 5

Blocks of strong rock move along a weak fracture in the rock (ex. Jointing, bedding plane, etc) or weak soil moves on top of a hard bedrock surface

Question 6

Flows

Answer 6

Occur when there is a large volume of water present in a mixture of soils and debris.
Rather than moving as coherent mass, the material flows downhill as a chaotic mixture

Debris flows are common in coastal mountains; heavy rainfalls on steep slopes covered in loose sediment, flows down the mountain and damages infrastructure

Question 7

Landslide causes and trigger

Answer 7

Causes: makes slope susceptible to movement without actually initiating failure
(Ex, geological, hydrological, human, etc)

Trigger: event that initiates failure