Oct 19 Lecture (Mass Wasting)

Question 1

how do mega-landslides act as a mechanism for colonization?

Answer 1

1. debris avalanche occurs
2. light material floats, including living things like bugs
3. winds/ ocean currents disperse the floating material to neighboring islands

Question 2

mass movement preventative measures (6)

Answer 2

1. reduce slope angle (put supporting material at base, reduce weight on slope)
2. build retention structures
3. leave stabilizing vegetation
4. decrease water content/ pore pressure of the rock/ soil
5. other slope stabilization techniques: rock bolts, verticals piles, support walls
6. avoid! build outside the range of falling rocks

Question 3

How does water affect the soil on slopes?

Answer 3

• fills voids and increases weight which increases driving forces
• exerts pore pressures which decrease effective stress/ strength

Question 4

in what way do logging and fires have the same effect on the land

Answer 4

decrease in vegetation= increase mass movements

eg. after fort mac fire, the hill in the city was found to be moving (not stable to rebuild on)