EV1005 - L10 Mass Movement

Question 1

What is the difference between weathering and erosion?

Answer 1

Weathering the products stay in situ and erosion they are moved downslope

Question 2

What is the difference between erosion and mass wasting?

Answer 2

Mass wasting is the downslope movement of material due to gravity alone. Not erosive agencies of water wind or ice etc

Question 3

How does debris move in mass wasting?

Answer 3

in a coherent or semi-coherent whole

Question 4

What are some well known landslides that occurred in Australia? (2)

Answer 4

Threadbo in 1997 Gracetown, WA in 1996

Question 5

How many fatalities were in the Threadbo landslide in 1997?

Answer 5

18 fatalities

Question 6

How many fatalities were in the Gracetown landslide in 1996?

Answer 6

9 fatalities

Question 7

Order these mass movements in order of slowest to fastest Fall (rock, earth or debris fall) Flow (avalanche) Flow (creeping) Slide (earth slide or debris slide) Slide (slump)

Answer 7

Flow (creeping) Extremely slow Slide (slump) Slow Slide (earth slide or debris slide) Rapid Flow (avalanche) Very rapid Fall (rock, earth or debris fall) Extremely Rapid

Question 8

What causes soil creep by heaving? (3)

Answer 8

Freezing and thawing of soil Wet and dry conditions Burrowing/plant roots

Question 9

How to trees behave when experiencing soil creep from heaving processes?

Answer 9

They bend at the base and become curved

Question 10

Define solifluction

Answer 10

The slow movement of saturated ground ofer frozen soil

Question 11

Give Case studies for mudflow

Answer 11

Lahar - Mt St Helens, Mt Pinatubo, Nevado del Ruiz

Question 12

How long was the Mt St Helens mudflow? (km)

Answer 12

90 Kilometres long

Question 13

How deep was the Mt St Helens mudflow? (m)

Answer 13

60 meters deep

Question 14

How fast did the St Mt Helens mudflow travel? (km/hr)

Answer 14

Max 145km/hr

Question 15

What movement occurs in an earth or debris slump?

Answer 15

The rotational movement of semi-coherent blocks

Question 16

What is the earthflow section of a slump and where is it located?

Answer 16

The earth that travels over the surface of the ground. Occurring at the downward side of the slump (pic 17/44)

Question 17

Where is the Headward growth of a slump located?

Answer 17

At the top of the slump

Question 18

Where do landslides often occur around cairns?

Answer 18

Over roads where land has been cut away leaving a steeper than natural slope. Debris Fals onto the roads and blocks traffic

Question 19

Are rock slides often dry or wet?

Answer 19

Dry

Question 20

True or False Mass movement only occurs on land

Answer 20

False

Question 21

True or False Submarine mass movements pose no danger to populations

Answer 21

False The chances are small that it would pose a threat but, if the movement is large enough, it may cause a tsunami

Question 22

What factors influence slope stability? (4)

Answer 22

Slope Angle Soil Texture Water Vegetation

Question 23

True or False When water completely fills the pore spaces between particles in soil this creates bonds holding the soil in place

Answer 23

False It keeps the particles apart and allows them to flow. When soil is not saturated, surface tension of water in pore spaces binds particles together

Question 24

How does vegetation influence slope stability?

Answer 24

Removes water Creates interlocking network of roots

Question 25

What can cause landslides? (4)

Answer 25

Earthquakes Rainfall Volcanic eruptions Human intervention

Question 26

What are examples of human interventions that can result in landslides? (5)

Answer 26

Oversteepening of slopes for roads and buildings removal of vegetation adding weight to a slope by buildings Adding water through pipes leaking, septic systems or irrigation Building dams raising groundwater level and adding weight to the land

Question 27

What is a very famous case study for a mass movement?

Answer 27

Yungay, Peru

Question 28

How many deaths occurred from the Yungay avalanche? (thousand)

Answer 28

18,000

Question 29

What caused the Yungay avalanche?

Answer 29

An earthquake

Question 30

Amberfan A) Landslide B) Earthquake C) Volcano D) Flood E) Mudflow

Answer 30

Landslide

Question 31

Yungay A) Landslide B) Earthquake C) Volcano D) Flood E) Mudflow

Answer 31

Landslide

Question 32

Gros Ventre A) Landslide B) Earthquake C) Volcano D) Flood E) Mudflow

Answer 32

Landslide

Question 33

Pu’u O’o A) Landslide B) Earthquake C) Volcano D) Flood E) Mudflow

Answer 33

Volcano with landslides falling into the sea

Question 34

How many people were killed in the Amberfan landslides?

Answer 34

144 (including 116 primary school children and 5 teachers)

Question 35

What caused the Amberfan landslide?

Answer 35

Liquifaction

Question 36

What are methods of prevention and control for mass movements? (5)

Answer 36

Retaining devices (netting, fencing, rock bolts)

Water/drainage control

Excavation and redistribution

Diversion or retention

Planting vegitation

Question 37

Mt St Helens A) Landslide B) Earthquake C) Volcano D) Flood E) Mudflow

Answer 37

Mudflow

Question 38

Threadbo A) Landslide B) Earthquake C) Volcano D) Flood E) Mudflow

Answer 38

Australian landslide

Question 39

Gracetown A) Landslide B) Earthquake C) Volcano D) Flood E) Mudflow

Answer 39

Australian landslide

Question 40

Mt Pinatabo A) Landslide B) Earthquake C) Volcano D) Flood E) Mudflow

Answer 40

Mudflow