short q- mass movement Flashcards
Define mass movement
Mass movement is the movement of regolith down slope under the influence of gravity
What is REGOLITH?
It is loose material like rock soil and mud that is poorly held together and move down slope under gravity
What are the natural factors that influence mass movement?
Gradient, water content, slope material, vegetation
How does gradient influence mass movement?
The speaker by the slope, the less stable it is and the faster the mass movement will occur
How does water content influence mass movement?
The higher the water content of regolith the faster and more likely it is to fall water at weight and access a lubricant
How does slope material influence mass movement?
It is less likely to occur on slopes made of compacted material like solid rock and is more likely to occur on uncompacted material like sand and Boulder as it is less held together
How old does vegetation influence mass movement?
The root of vegetation help by soils together making mass movement less likely to occur. It also soaks up water so reduces water content and weight.
What are other factors that influence mass movement?
Volcanic activity
Human activity
Earthquakes
How do volcanic activity influence mass movement?
It releases large amount of heat and lava which can lead to lahars and mud flows as it melts snow and increases water content
How do earthquakes influence mass movement?
Certain vibrations or changes in the surface of the earth can cause ground to become unstable and more likely to move down slope
How does human activity influence mass movement?
Road construction can trigger mass movement as digging and undercut slopes. Deforestation and poor farming practices can weaken soil structure
What is a type of very slow mass movement and describe it
Soil creep
It moves half a centimetre a year on gentle slopes
It is caused by freeze Thor action
What is a type of slow mass movement?
Soilifluction
It occurs on high ground where soil is frozen at the base due to permafrost. During summer month so close to the surface doors but the underneath remains frozen so the top soil become saturated and moves slow slowly down slow due to gravity.
What is an earth flow?
It is a moderate speed mass movement that occurs on hills after heavy rainfall so on top lays an impermeable rock that becomes saturated and heavy so downslope
What is another type of moderate speed mass movement that is not Earth flow?
Slumping
This is when steep slopes of Un consolidated materials move down slope as the base of the slope is removed
What are the five types of fast mass movement?
Rockfall
Landslide
Lahar
Bog burst
Avalanche
Describe mass movement rockfall
Loose rocks fall from sleep slopes due to weathering
Describe a landslide
Cause in mountainous areas or coastlines where large sections of rock fracture and move down the slope
Describe mud flows
These are a very fast type of mass movement and occur as the soil becomes severely saturated by heavy rainfall and has the ability to flow as friction between it and underlying rock is reduced
Describe how a lahar farms
He and Lara from the volcanoes melt snow and forms lahars which are boiling mud that move rapidly down the mountain slope
Describe a bog burst
Okay, when saturated Pete along the slopes of bog become saturated and move down slope
Often happens where the wind farms are built
Describe how an avalanche farms
Snow moves down slope as a layer of poorly compacted snow is under the lion, new fresh snow and the weight of the new Fresno causes the poorly compacted layer to break and slide down slope
What are terracettes
Series of ridges that run across a hill formed form the slow downward movement of soil
Formed during soil creep
