UNIT 9 Mass movement

Question 1

what are the types of mass movement

Answer 1

Solufluction and creep
Slumping
Lahars and mudflows
debris flows
rockfalls and rockslides

Question 2

what is a mass movement

Answer 2

the downslope movement of rock, regolith, snow or ice driven by gravity

Question 3

You can distinguish Mass movements by

Answer 3

Material
velocity
Character
Environment

Question 4

What are the types of material in a mass movement

Answer 4

snow, rock, mud, ice

Question 5

What are the characters of sediment in mass movement

Answer 5

coherent or chaotic

wet or dry

Question 6

what are the mass movement environments

Answer 6

subaeriel submarine

Question 7

What is creep

Answer 7

slow downhill movement of regolith caused by seasonal expansion and contraction

Question 8

What is evidence of creep

Answer 8

Tilted telephone poles, sagging foundation, curving tree trunks

Question 9

WHat is solufluction

Answer 9

Tundra Creep where melted permafrost slowly flows over deeper frozen soil

Question 10

What are rock glaciers

Answer 10

rock glaciers are mixtures of rock fragments imbedded in ice

think breccia or conglomerate cemented in ice

because ice is relatively week it can flow slow down steep slopes

Question 11

what is slumping

Answer 11

mass movement by sliding of regolith in coherent blocks

have a head scarp (exposed failure)
and a bulging toe (material pile up)

Question 12

What is a mud flow

Answer 12

Mostly mud mass movement, depends on water content and slope angle

Question 13

what is a debris flow

Answer 13

mud flow mixed with pebbles and cobbles

Question 14

what are lahars

Answer 14

same process as a mudflow or debris flow but with volcanic ash instead of weathered regolith

super hot and scary and stuff

Question 15

what is a rock/debris slide

Answer 15

non vertical,
rock can move at 300km/h
rock slide if rock
debris slide if regolith

Question 16

what is an avalanche

Answer 16

the best beaver tail flavour

a turbulent cloud of debris and air
snow or other debris like rock or marine sediment

Question 17

wet snow avalanche speed

Answer 17

30km/h

Question 18

dry snow avalanche speed

Answer 18

20km/h

Question 19

avalanches flow through….

Answer 19

channels down mountains or underwater

Question 20

What is a rock / debris fall

Answer 20

vertical Freefall of mass
falls rapidly
caused by road cuts

Question 21

what happens in submarine slumps and debris flow

Answer 21

sediment breaks loose and flows down a canyon

the turbidity current slows and deposits sediment in a submarine fan

Question 22

in a turbidity current..

Answer 22

sediment and water flow chaotically downslope

Question 23

physics of mass movement

Answer 23

moves when the downslope force is greater than the resisting force

which is caused by many factors like chem bonds electrostatic attraction friction and surface tension

Question 24

sand angle of repose

Answer 24

35 deg

Question 25

coarse sand angle of repose

Answer 25

40 deg

Question 26

angular pebbles angle of repose

Answer 26

45 deg

Question 27

what are weak surfaces

Answer 27

saturated sand or clay layers joints parallel to surface weak sedimentary bedding metamorphic foliation

Question 28

what triggers mass movement

Answer 28

shocks vibrations liquefaction changes in slope loads, steepness and support changes in slope strength

Question 29

what causes shocks and vibrations

Answer 29

earthquakes storms trucks blasting

Question 30

what is liquefaction

Answer 30

when wet sediment shakes, grains can behave like fluid, solid sediment turns into a slurry

Question 31

what can cause changes in slope loads

Answer 31

addition of weight above a slope water infiltration construction

Question 32

what can cause changes in steepness (MM)

Answer 32

rivers and road cuts

Question 33

what can cause changes in support (MM)

Answer 33

undercutting may remove support and create a steeper slope

Question 34

what can cause changes in slope strength

Answer 34

weathering vegetation water content

Question 35

what happened in the vajont dam

Answer 35

water table rose above the dam and overflowed causing massive destruction

Question 36

what magnitude was the 1929 NFL earthquake

Answer 36

7.2

Question 37

Where do slope failures occur

Answer 37

HIGH RELIEF AREAS revers glaciers waves HIGH RAIN AREAS weathering heavy soil TECHTONIC AREAS

Question 38

how do you identify mass movement

Answer 38

look for indications of past mass movement such as head scarps, overtight power lined, dead or tilted trees

Question 39

how does vegetation prevent mass movement

Answer 39

the roots stabilize the potential failure plane

Question 40

what is regrading

Answer 40

cutting terrace steps to remove load and catch debris

Question 41

What is drainage in mass movement prevention

Answer 41

lowering the water table below a potential failure plane dries the plane and makes it stronger

Question 42

how can you reduce undercutting

Answer 42

divert a stream further from a cliff place riprap to absorb wave energy

Question 43

What are some ways engineered structures to help prevent the effects of mass movement

Answer 43

Retaining walls Jock bolts avalanche sheds

Question 44

When do you use controlled blasting

Answer 44

if a slide is inevitable,Avalanches usually

Question 45

what is nessecary to set a mass movement in motion

Answer 45

weathering, relief, a triggering event