Mass Movement Flashcards
What is mass movement ?
Mass movement is the movement of material downslope under the influence of gravity. The loose material is called regolith
What are factor which influence mass movement ?
Human interaction , gradient , vegetation, water content
How does human interaction influence mass movement ?
Construction of roads / rail which undercuts slopes making them unstable and steeper leading to mass movement e.g.rock fall
How does steeper slopes influence mass movement ?
Steeper slopes (gradient) increase the likelihood of mass movement. The steeper the slope the faster the mass movement
How does water content influence mass movement ?
Seepage after heavy rainfall , can act as lubricant making materials more likely to slide. Water also adds weight to the slope
How does soil creep occur ?
Soil creep occurs as soil moves very slowly down gentle slopes at a speed of about 1cm per year. This is the slowest form of mass movement. You only notices its effect on the andscape form the clues it leaves after many years
What does soil creep cause in the landscape ?
Soil piles up behind walls , causing them to bulge and break
Tree trunks and fences bend in all directions
Pols may lean in the direction of the solid creep
Soil sometimes accumulates in series of small ridges called terracettles
Where is the soil creep the greatest at ?
Greatest at the surface
When do landslide occur?
A landslide is the sudden movement of rock , soil and debris down a slope due to gravity -
It happens when the stability of the slope is weakened by factors such as heavy rainfall , deforestation and / or human activities like construction of roads , rail and buildings
These factors reduce friction and support , causing materials to slide downhill
What is the name of the landslide you have studied ?
The 2018 Southern California landslide , montecito
When did the landslide you have studied occur ?
Occurred on January 9 , 2018
What was the damage of the 2018 landslide ?
23 people were killed , many over were injured and properties were damaged
How did the landslide 2018 occur ?
It occurred following heavy rainfall in areas where vegetation was destroyed by the Thomas forest fires from 2017 , heavy rainfall left the soil unstable. This triggered a fast-moving landslide destroying homes , roads and infrastructure in montecito
How does vegetation influence mass movement ?
Roots can help blind soil together and tress also absorb much of water. Deforestation increases the risk of mass movement
What is the slow mass movement
Soil creep
What are the fast mass movements ?
Landslide , avalanche , bog burst , mudflow
