lecture 13

Question 1

2 classifications of mass movements

Answer 1

1. material being moved ex. rock, mud, earth, debri
2. type of movement ex. fall, topple, avalanche, slide
   furthur classification- speed of movement and water content

Question 2

speed of mass movement

Answer 2

slow- earth flows and soil creep

rapid- debris flows, snow avalanches and rock falls

Question 3

rock falls

Answer 3

movement is mostly downward, free fall of block from a free face following opening of fracture

Question 4

block slides

Answer 4

material slips along basal failure plane, making movement downard and outward
involves a block of intact rock

Question 5

rock slides

Answer 5

rock breaks up as it slides, can be rotational (above curved surface) or translational (above planar surface) may have head scarp and toe

Question 6

debris slides

Answer 6

if material fragments as it slides it becomes a debris slide, debris is commonly made up of a mix of broke up rock, soil and vegetiation

Question 7

flows

Answer 7

flow: if material becomes fluidized

earth flow: soil, debris flow: fragmented rock, mud flow: wet mud or lahar: wet volcanic ash

Question 8

debris flow

Answer 8

kedarnth india were triggered by monsoon rains in 2013, flows originated in mountains but travel down river valleys where 6000 people killed

Question 9

soil creep

Answer 9

slowest but most common slope failure caused by cyclic expansion and contraction of soil due to freezing/thawing of clay materials
expansion acts in the direction perpendicular to hill slope where contraction under gravity is vertical - slow downaward creep

Question 10

composite landslide types

Answer 10

start off as one type and evolve into another

- rotational landslide–>debris slide–> debris flow

Question 11

sturzstrom

Answer 11

type of rock avalanche that has a long horizontal runout relative to its vertical drop
particle vibrations trapped air pockets or frictional melting at base of landslide reduce friction sufficiently

Question 12

why can sturzstrom travel so far

Answer 12

base of landslide has particles being smashed under high pressure and vibrate as a pocket of air which lowers friction
could be frictional melting becasue its so hot

Question 13

rock avalanches

Answer 13

rock falls often morph into rock avalanches when they hit slopes below and the intact rock disintegrates
builds scree slopes over time

Question 14

landslide hazard mapping

Answer 14

can help limit development within most prone areas

Question 15

most effective - landslide mitigation

Answer 15

removing hazard–> scaling (removing loose rock) or benching (remodelling the slope as series of steps)

Question 16

mechanically reducing hazard- landslide mitigation

Answer 16

1. unloading the head
2. reinforcing the body (meshing and bolts)
3. supporting the toe (offshore breakwaters to resist erosion)

Question 17

landslide monitoring

Answer 17

inSAR –> large antenna simulated by combining multiple images along track (synthetic aperature of radar) might resolve pixel that is moving from landslide
- satellites can monitor ground deformation associated with slow moving landslides but predicting if and when these fail catastrophically is difficult

Question 18

early warning system

Answer 18

debris flows in illgraben valley in switzerland are common so locals set up early warning system