LA L3

Question 1

What does a landslide’s type depend on?

Answer 1

local geology of an area and the type of geological material involved

Question 2

Which are rapid-moving landslides?

Answer 2

FALLS: rock fall, debris fall, earth fall

TOPPLES: rock block topple, earth block topple

SLIDES: rock slide, debris slide

SPREADS: earth spread

FLOWS: debris flow, mud flow, debris avalanche, sand flow slide, silt flow slide, earth flow slide

COMPLEX: rock avalanche

Question 3

Which are slow-moving landslides?

Answer 3

TOPPLES: flexural topple

SLIDES: rock slump, earth slump, earth slide

SPREADS: rock spread

FLOWS: rock creep, slope sagging, soil creep, solifluction, dry sand flow, earth flow

COMPLEX: earth slump-earth flow

Question 4

What is Velocity Class 7’s speed? Human response? Probable destructive significance?

Answer 4

Speed: 5 m/s
Human Response: Nil (sudden death)

Catastrophe of major violence, buildings destroyed by impact of displaced material; many deaths; escape unlikely

Question 5

What is Velocity Class 6’s speed? Human response? Probable destructive significance?

Answer 5

3m/min (very rapid); Human Response: Nil (deaths); some lives lost, velocity too great to permit all persons to escape

Question 6

What is Velocity Class 5’s speed? Human response? Probable destructive significance?

Answer 6

1.8m/h (rapid); Human response: evacuation; Escape evacuation possible; structures, possessions, and equipment destroyed

Question 7

What is Velocity Class 4’s speed? Human response? Probable destructive significance?

Answer 7

13m/month (moderate) ; Evacuation; Some temporary and unaffected structures can be temporarily maintained

Question 8

What is Velocity Class 3’s speed? Human response? Probable destructive significance?

Answer 8

1.6m/year (slow); Maintenance; Remedial construction can be undertaken during movement; insensitive structures can be maintained with frequent maintenance work if total movement is not large during a particular acceleration phase

Question 9

What is Velocity Class 2’s speed? Human response? Probable destructive significance?

Answer 9

16mm/y (very slow); Maintenance; Some permanent structures undamaged by movement

Question 10

What is Velocity Class 1’s speed? Human response? Probable destructive significance?

Answer 10

<16 mm/year (extremely slow); Nil (minimal disruption); Imperceptible without instruments; construction possible with precautions

Question 11

What is a fall?

Answer 11

a sudden, vertical movement of material. very fast moving, usually involve rocks, are often related to the geologic structure of the slope.

Question 12

Where do falls occur?

Answer 12

on steep slopes with loose rock that may periodically detach from a surface on which little or no shear/sliding takes place. The material then descends mainly through the air by falling, bouncing, or rolling

Question 13

What is a rock fall?

Answer 13

When broken bedrock is falling

Question 14

Out of all the landslide types, what type does gravity have the most influence on?

Answer 14

falls

Question 15

What do topples require?

Answer 15

Topples require fractured material oriented perpendicular and parallel to the slope face, which allows the material to be broken up into coherent pieces that roll forward down a slope.

Question 16

Why is there no such thing as a debris topple?

Answer 16

because debris is unsorted and consists of material of variety of sizes which usually does not remain in coherent blocks upon failure.

Question 17

What are slides?What do slides involve?

Answer 17

In general, slide velocities vary from slow to fast, usually involve soil, rock, or debris moving along a surface of failure (either curved or straight)

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

Question 18

Describe rotational slides:

Answer 18

where blocks of soil or weak rock move along a curved rupture surface that forms due to the shear forces in the slope exceeding the shear strength of the soils/rocks. During failure, blocks of material rotate and tilt.

Question 19

Describe translational slides.

Answer 19

where blocks of strong rock move upon a weak plane or pairs of intersecting weak planes in the rock (joints, faults, bedding, etc.).

Question 20

Where do lateral spreads occur?

Answer 20

where there is a slow to rapid extensional movement of rock or soil - usually related to the sudden liquefaction of a weak soil layer (such as quick clays) and often triggered by earthquakes or explosions. Such spreads can occur on relatively shallow slopes.

Question 21

What is liquefaction?

Answer 21

the sudden loss of strength in the soil transforming its behaviour into that of a liquid