Mass Wastings

Question 1

Landslides are linked to many other _______

Answer 1

natural hazards

Question 2

Landslide benefits:

• disturbances increase ______
• provide ________ in steep terrain

Answer 2

• ecological diversity

- habitable terraces

Question 3

Slopes are dynamic evolving systems and are the products of _____ and ____

Answer 3

• evolving
• substrate
• climate

Question 4

Fatalities due to landalides 1900-2015

Answer 4

almost 70,000

Question 5

slopes fail when ________ exceed the strength of the ____ or ____ that comprise the slope

Answer 5

• gravitational forces
• rock
• soil

Question 6

Slopes fail when they are _______ or _____

Answer 6

• oversteepened

- debuttressed

Question 7

slope zones of weakness develop due to certain combinations of _______ and _______ accumulation over impermeable _________ layers

Answer 7

• soils/bedrock
• groundwater
• silt and clay

Question 8

Landslides are classified by:

Answer 8

• type of material
• type of motion
• rate of movement
• water content

Question 9

unconsolidated material is ______ and consolidated material is ______ and ______

Answer 9

• loose
• cohesive
• adhesive

Question 10

Role of water in landslides:

• adds ____ to slope
• decreases _______
• clay minerals become hydrated and _____ with high pore pressure
• minerals holding ________ together may ______

Answer 10

• mass
• material strength
• expand
• individual grains
• dissolve

Question 11

Rockfall (consolidated)

Answer 11

• free fall or bouncing of rock

- 10km/hr

Question 12

Rock slide/avalanche (consolidated)

Answer 12

• flow of fragmented rock from large rock slide or fall

- 10km/hr

Question 13

Causes of rock slide/avalanche

Answer 13

• vibration
• undercutting
• differential weathering

Question 14

creep (consolidated)

Answer 14

• cm/yr

- rock movement along deep failure plains

Question 15

toppling (consolidated)

Answer 15

• movement of rock around pivot point away from slope
• common in steeply dipping joints/bedding planes
• km/hr

Question 16

slump (unconsolidated)

Answer 16

• slow slide of material as coherent unit

- concave failure surface

Question 17

Causes of slumps

Answer 17

• liquefaction
• quick clay
• km/hr

Question 18

flow (unconsolidated) + triggers

Answer 18

• significant internal deformation
• dense fluid can transport large blocks of material
• can be triggered by rainfall/ snow melt

Question 19

creep (unconsolidated)

Answer 19

• slow flow, slide or deformation

- soil expansion due to water in clay or freeze/thaw

Question 20

earth flows

Answer 20

fluid movement of fine grained soils

Question 21

debris/mud flows

Answer 21

fluid movement of coarser material & rock in mud matrix

Question 22

debris avalanche

Answer 22

rapid movement of slope materials (70km/hr)

Question 23

solifluction

Answer 23

soil freeze/thaw in cold regions. Upper “active layer” deforms over frozen layer

Question 24

submarine mass movements can be triggered by:

Answer 24

• accumulated sediments
• earthquakes
• extreme tides

Question 25

submarine mass movements are commen at ______ and may cause _______

Answer 25

- fronts of active defaults or volcanic islands | - tsunamis

Question 26

complex mass movements involve some ______ of mass movement types

Answer 26

combination

Question 27

driving forces

Answer 27

drive rock or sediment down slops

Question 28

resistive forces

Answer 28

- oppose driving forces | - shear strength, slope of material

Question 29

Material type affects event ____ and ____

Answer 29

- frequency | - type

Question 30

Important characteristics of minerals in mass wastings

Answer 30

- mineral composition - degree of consolidation - planes of weakness - inclanation of plain

Question 31

clay

Answer 31

fine grained sediment created by chemical weathering of rocks

Question 32

clay has low ____ and high _____

Answer 32

- strength | - pore pressure

Question 33

steep slopes increase _______

Answer 33

driving force

Question 34

high topography means high ______

Answer 34

gravitational potential energy

Question 35

Vegetation influences mass wastings through:

Answer 35

- protective cover - increases material strength - increases load

Question 36

_____ is almost always involved in mass movement

Answer 36

water

Question 37

how water affects mass movement

Answer 37

- saturation increases probability of landslides - deep infiltration may cause delayed triggering - may erode base of slope

Question 38

Factors contributing to increased risk of landslides

Answer 38

- regrading surfaces - cut and fill - vegetation removal - surface loading - undercutting slopes - watering lawns

Question 39

Minimizing landslide risk: - _______ areas where landslides have occurred in the past or are likely to occur - _____ these sites - ______ exposure with engineered structures - ______ landslides with engineered structures - _____ active slides - _______ of impending failure

Answer 39

- identify - avoid - reduce - prevent - control - warn

Question 40

indicators of potential landslides: - _______ cracks on hillside - _________ of valley wall - lobate area of _______ on hillside - _____ trees - bedrock laying ______ to slope - ______ terrain

Answer 40

- crescent shaped - scalloped crest - exposed material - tilted - parallel - hummocky (bumpy)

Question 41

drains cannot prevent ______, but can _________

Answer 41

- large landslides | - minimize hazards

Question 42

objective of drains

Answer 42

keep water from infiltrating slope

Question 43

cut and fill

Answer 43

- material moved from upper to lower slope - reduces gradient, increases resistent forces - not applicable to high/steep slopes

Question 44

benches or steps: - surface drains ______ - provide sites for ______

Answer 44

- divert runoff | - falling rock/small slides

Question 45

_______ are one of the most common landslide mitigation measures

Answer 45

slope supports

Question 46

slops supports anchor below ______, have backfill with ______ material, and allow for ______

Answer 46

- slope base - permeable - drainage

Question 47

rock bolts are _____ that are inserted into _____ and anchored with _______

Answer 47

- steel rods - drill holes - facing plates

Question 48

screens and fences are intended to intercept _______ and do not provide protection from _______

Answer 48

- small rocks | - larger slides

Question 49

types of landslide identifiers

Answer 49

- human - electrical - tiltmeters - geophones - rain guages - surveying - sattelite