EV1005 - L10 Mass Movement Flashcards
What is the difference between weathering and erosion?
Weathering the products stay in situ and erosion they are moved downslope
What is the difference between erosion and mass wasting?
Mass wasting is the downslope movement of material due to gravity alone. Not erosive agencies of water wind or ice etc
How does debris move in mass wasting?
in a coherent or semi-coherent whole
What are some well known landslides that occurred in Australia? (2)
Threadbo in 1997 Gracetown, WA in 1996
How many fatalities were in the Threadbo landslide in 1997?
18 fatalities
How many fatalities were in the Gracetown landslide in 1996?
9 fatalities
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)
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
What causes soil creep by heaving? (3)
Freezing and thawing of soil Wet and dry conditions Burrowing/plant roots
How to trees behave when experiencing soil creep from heaving processes?
They bend at the base and become curved
Define solifluction
The slow movement of saturated ground ofer frozen soil
Give Case studies for mudflow
Lahar - Mt St Helens, Mt Pinatubo, Nevado del Ruiz
How long was the Mt St Helens mudflow? (km)
90 Kilometres long
How deep was the Mt St Helens mudflow? (m)
60 meters deep
How fast did the St Mt Helens mudflow travel? (km/hr)
Max 145km/hr
What movement occurs in an earth or debris slump?
The rotational movement of semi-coherent blocks
What is the earthflow section of a slump and where is it located?
The earth that travels over the surface of the ground. Occurring at the downward side of the slump (pic 17/44)
Where is the Headward growth of a slump located?
At the top of the slump
Where do landslides often occur around cairns?
Over roads where land has been cut away leaving a steeper than natural slope. Debris Fals onto the roads and blocks traffic
Are rock slides often dry or wet?
Dry
True or False Mass movement only occurs on land
False
True or False Submarine mass movements pose no danger to populations
False The chances are small that it would pose a threat but, if the movement is large enough, it may cause a tsunami
What factors influence slope stability? (4)
Slope Angle Soil Texture Water Vegetation
True or False When water completely fills the pore spaces between particles in soil this creates bonds holding the soil in place
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
How does vegetation influence slope stability?
Removes water Creates interlocking network of roots
