Mass Movement Flashcards
What is mass movement
Mass movement is the movement of loose earth materials (soil, stones, mud) called regality down a slope under the influence of gravity
Why does slope effect mass movement
The steeper the slope, the more likely that mass movement will occur
Why does water effect mass movement
Heavy rainfall will make the soil heavier and easier to move downhill - it will act like a lubricant
Why does lack of vegetation effect mass movement
The roots of trees and plants hold the soil, so when they are cleared away, mass movement is more likely
How do people effect mass movement
Work carried out by people, such as digging and drilling, will disturb the ground and cause mass movement
Soil creep
Slow movement 1cm a year Evidence; Fences and trees bend downhill Terracettes Wall collapse
Landslides
Rapid movement
Caused by undercutting
Coastal erosion and earthquakes
Heavy rains loosen the soil
Coastal cliff collapse
Quicker when they have been weakened by the waves
Waves wear away the base of the cliff
Bogbursts
Fast movements
Loosened by heavy rainfall
Or by wind turbine when vegetation is removed or by work
Like a river of turf or peat flowing down
Mudflows
Fast movements
Caused after heavy rainfall or by volcanic activity
Lahar - melted snow turned into a river of mud
Case study: a mudflow
Nevada deal Ruiz a snow covered volcanic mountain in Colombia
It erupted in 1985
5000 houses were covered by the lahar
Killed 23000 people
