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Geog375Gmphlgy > Slope Process and Slope Stability > Flashcards

Slope Process and Slope Stability Flashcards

1
Q

What was Canada’s worst natural disaster?

A
  • Frank Slide
  • 1903
  • 82 million tonnes of limestone
  • Killed approx. 70 people in mining town of Frank
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2
Q

Objectives of slope processes

A
  • Conceptualize slopes as systems where downslope forces move earth surface materials
  • Review common features (Slides, flows, falls, spreads, creep) and classification schemes (morphological and rheological
  • Expand with case study examples, discuss hazards and risks
  • Discuss important morphometrics and indicators used to interpret activity
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3
Q

How do landscape materials get from mountain tops to valley floors?

A
  • slope processes and mass wasting
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4
Q

Why are submarine failures of importance for terrestrial habitats?

A
  • underwater displacement can cause tsunami’s

- infrastructure on deltas and other marine envrs

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5
Q

Frequency-magnitude relations

A
  • Moderately sized transport events do the most geo work in the landscape as a consequence of the frequency of moderate sized events
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6
Q

What are 2 big factors for geomorphic work/potential damage?

A
  • How bit is it
  • How often does it happen
  • i.e. Frequency-magnitude relationship
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7
Q

What affects the angle of internal friction for granular materials?

A
  • Surface roughness
  • Packing
  • Grain shape
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8
Q

When is the angle of internal friction higher?

A
  • Closer packing
  • Grains of different sizes
  • Angular grains
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9
Q

When is the angle of internal friction lower?

A
  • Open packing
  • Uniform particle sizes
    = fewer points of contact for friction
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10
Q

Cohesion

A
  • How well things stick together

- Rootlets, electro-static bonds in clays, cementing agents (salt oxides)

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11
Q

Internal Friction

A
  • Planar friction angle
  • Mechanical (bulk) resistance of grain-grain contact
  • f (grain size, shape, sorting, compaction)
  • Controls Stress in unconsolidated deposits, Failure when > than angle of internal friction
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12
Q

What are 2 measures that control rheological responses?

A
  • Angle of repose

- Angle of sliding friction

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13
Q

Angle of repose

A
  • Angle of rest of dry sediment (25 - 40 degrees)

- Static, stationary, friction

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14
Q

Angle of sliding friction

A
  • Angle at which sediment fails
  • up to 10 degrees > angle of repose
  • Dynamic friction threshold
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15
Q

What is the primary driving force in the landscape?

A
  • Gravity
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16
Q

On a slope, what is the Force of gravity (Fg) divided into?

A

2 vectors:

  • Downslope component
  • Normal component
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17
Q

What is the frictional force proportional to?

A
  • frictional is proportional to normal force
  • friction decreases as slope increases,
  • Down slope gravitational component increase when slope increases and normal force decreases
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18
Q

What is the main thing slope failure is dependent on?

A

Slope!

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19
Q

What is the driving force?

A
  • Shear stress

- Derived from soil bulk density, gravitational acceleration, and soil depth

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20
Q

What is the specific weight of the soil?

A
  • soil bulk density x gravitational acceleration
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21
Q

What is the resistance to shear stress expressed by?

A

the Mohr-Coulomb eqn.

- Describes the ability of material to resist sliding

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22
Q

What does Soil strength depend on?

A
  • Soil cohesion
  • Normal force
  • Pore water pressure
  • Coefficient of friction
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23
Q

Angle of internal friction

A
  • phi
  • angle where shear failure occurs
  • can be estimated in the field (driving a probe into the ground)
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24
Q

What is the normal force?

A
  • imposed by the weight of the solids and water above a particular point in the soil and resists downhill movement
  • Force per unit area
  • Frictional resistance on the sliding plane
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25
Q

What does high pore water pressure do to the normal force?

A
  • reduces normal force and the frictional strength of soil

- Forces the particles apart and reduces the friction

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26
Q

What is the difference between Phi and Theta?

A
  • Phi is the angle where shear failure occurs
  • Theta is the slope angle
  • They are not the same thing
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27
Q

How is the Soil (Shear) Strength, S, calculated?

A

S = soil cohesion plus [(normal force per unit area - pore water pressure) x tan of the angle of internal friction]

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28
Q

What is Cohesion caused by?

A
  • Chemical bonding and electrostatic attraction between particles of soil, not simply compressive forces (squeeze sand together and nothing happens)
  • roots or inter-particle bonds
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29
Q

What holds soils with lots of organic matter together?

A
  • roots can physically hold soils together
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30
Q

What happens in silts and clays that generally don’t chemically bond to each other?

A
  • electrostatic forces due to the effects of capillary water between oil particles can provide a bond
  • Clays which are charged are cohesive and stick together
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31
Q

How is pore water pressure calculated?

A
  • It is the product of slope normal component of the bulk water density, gravity, and soil thickness, and cos of slope angle
  • High pore water pressure decreases soil strength
  • Measured in units of pressure, Newtons per square meter
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32
Q

Can pore water pressure be mitigated?

A
  • Yes

- ex. Drains to capture moisture and reduce pressure

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33
Q

Factor of Safety

A
  • Describes the stability of a slope
  • Ratio between forces resisting and driving movement
  • Fs = 1 forces balanced, threshold for instability
  • Fs > 1 (Strength > stress) = Stable
  • Fs < 1 (S
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34
Q

Factor of Safety for a dry soil with no cohesion

A
  • dry = no water pressure
  • no cohesion = no clay
  • The resisting force is the soil strength from the coulomb eqn and the driving force is shear stress
  • Soil Density includes only the weight of soil particles which occupy 60 percent of the total volume (1590kg/m^3)
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35
Q

Factor of Safety for a dry soil with cohesion

A
  • dry = no water pressure
  • cohesion = clay
  • Soil density remains the same (1600kg/m^3)
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36
Q

Factor of Safety for a wet soil with cohesion

A
  • wet = water pressure
  • cohesion = clay
  • Soil density includes weight of the soil particles and the water in the pore spaces (2050kg/m^3)
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37
Q

What happens to the Fs if slope increases

A
  • denominator (stress) becomes large

- Fs decreases

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38
Q

What happens to Fs if a wet soil loses moisture?

A
  • numerator (strength) becomes large

- FS increases

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39
Q

What happens to Fs if a slope is logged?

A
  • cohesion decreases
  • numerator (strength) becomes smaller
  • Fs decreases
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40
Q

What happens to Fs if a soil thickness is increased?

A
  • denominator (stress) gets larger proportionally to numerator (strength)
  • Fs decreases
  • But balances out with cohesion present
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41
Q

External Factors that Increase Shear Stress

A
  • Removal of support (erosion, human activity i.e. road cuts etc)
  • Addition of mass (Natural i.e. talus/rain, or Human i.e. fills, buildings etc.)
  • Earthquakes
  • Regional tilting
  • Removal of underlying support (undercutting, solution etc or human i.e. mining)
  • Lateral pressure (Natural swelling, expansion, water addition)
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42
Q

Internal factors that decrease Shear Strength

A
  • Weathering and physicochemical reactions (lowers cohesion):
    • Disintegration (lowers cohesion)
    • Hydration (lowers cohesion)
    • Base exchange
    • Solution
    • Drying
  • Pore water (Buoyancy, Capillary tension)
  • Structural Changes (Remolding, Fracturing)
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43
Q

What do internal factors that control slope failure tend to do?

A

Decrease Shear Strength

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44
Q

What do External factors that control slope failure tend to do?

A

Increase Shear Stress

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45
Q

How do slopes achieve stability?

A

Through failure

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46
Q

Dalrymple 1968

A
  • 9 slope elements described by geomorphology and dominant transport processes and pathways
  • Provided a simple way to describe and map slopes to show down slope variation
  • Reality rarely has all 9 components
  • Stable profile while unstable shows steps and irregular features
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47
Q

9 Slope elements

A
  • Interfluve
  • Seepage slope
  • Convex creep slope
  • Fall face
  • Transportational midslope
  • Colluvial footslope
  • Alluvial toeslope
  • Channel wall
  • Channel bed
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48
Q

Interfluve

A

Pedogenetic processes associated with vertical subsurface soil water movement
- Modal slope angle 0 - 1 degrees

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49
Q

Seepage Slope

A

Mechanical and chemical elevation by lateral subsurface water movement
- Modal slope angle 2 - 4 degrees

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50
Q

Convex Creep Slope

A

Soil cree, terracette formation

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51
Q

Fall Face

A
  • Fall, slide, chemical and physical weathering

- minimum angle 45 degrees but normally over 65

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52
Q

Transportational midslope

A
  • Transportation of material by mass movement (flow, slide, slump, creep), terracotta formation, surface and subsurface water action
  • Frequently occurring at 26 to 35 degree slope angles
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53
Q

Colluvial footslope

A
  • Redeposition of material by mass movement and some surface wash
  • Fan formation
  • Transportation of material, creep, subsurface water action
54
Q

Alluvial toeslope

A
  • Alluvial depostion
  • Processes resulting from subsurface water movement
  • 0 to 4 degrees
  • Movement in a downvalley direction
55
Q

Channel wall

A
  • Corrasion, slumping, fall

- Movement in a downvalley direction

56
Q

Channel Bed

A
  • Transportation of material downvalley by surface water action
  • periodic aggradation and corrasion
57
Q

Dalrymple, where is the transition from pedogenic to colluvial processes?

A
  • Between Seepage slope and Convex creep slope
58
Q

Dalrymple, where is the transition from colluvial to alluvial processes?

A
  • Between Colluvial footstep and Alluvia toeslope
59
Q

Dalrymple, where is the transition from alluvial to fluvial processes?

A
  • At the Channel wall between the alluvial toeslope and channel bed
60
Q

How does Dalrymple’s model compare with reality?

A
  • All 9 units rarely occur on one slope or in the same order
  • But general shape of convex morphing to concave profile is fairly common
  • Sometimes repeated units reflect compositional changes
61
Q

Slopes reflect imbalanced forces acting on their mass controlled by:

A
  • Geology (type, weathering, joints/fractures, orientation)
  • Sediment properties (thickness, shape, sorting, rheology, Mc)
  • Topography (steepness, aspect, pre-existing features, vegetation, land-use)
62
Q

What is the ideal stable profile?

A

Convex-straight-concave

63
Q

What do slopes out of equilibrium show?

A
  • Steps or irregular features

- Steeps bring out of stability and it will try to return to convex-straight-concave profile

64
Q

How do slopes naturally achieve balance with forces acting on their mass?

A
  • By adjusting slope angle, through failure
65
Q

Classification of movements: Type of movement

A
  • Fall
  • Topple
  • Slide (rotational, translational)
  • Lateral Spreads
  • Flows
  • Complex
66
Q

Classification of movements: Type of Material, Bedrock

A
  • Rockfall
  • Rock Topple
  • Rock slump
  • Rock block slide
  • Rock slide
  • Rock spread
  • Rock flow (deep creep)
67
Q

Classification of movements: Type of Material, Unconsolidated Coarse

A
  • Debris fall
  • Debris topple
  • Debris slump
  • Debris block slide
  • Debris spread
  • Debris flow (soil creep)
68
Q

Classification of movements: Type of Material, Unconsolidated Fine

A
  • Earth fall
  • Earth topple
  • Earth slump
  • Earth block slide
  • Earthslide
  • Earth spread
  • Earthflow (soil creep)
69
Q

What are mass movement categories based on?

A
  • Type of movement
  • Further subdivisions based on material type (bedrock vs. unconsolidated sediments)
  • Mechanism of failure
  • Sedimentary and rheological properties
  • Moisture content
  • Speed of movement
70
Q

Ternary diagram of mass movement classification

A
  • Heave (up, down due to alternate freeze-thaw of soils, type of creep)
  • Flow (wetter)
  • Slide (dryer)
71
Q

Parts of a landslide, top to bottom

A
  • Crown (should have crown cracks)
  • Main Scarp
  • Head
  • Minor Scarp
    Foot:
  • Transverse cracks
  • Transverse ridges
  • Radial cracks
  • Toe
    Surfaces:
  • Surface of rupture
  • Main Body
  • Toe of surface of rupture
  • Surface of separation
72
Q

Rheological classification of mass movements

A
  • Velocity vs. sediment conc.
  • Fluid (liquid) to solid (plastic) behaviour
  • Fast (inertial) vs. slow (viscous or friction)
  • Streamflow (top left) to creep (bottom right)
73
Q

What is the Sedimentological classification for movements?

A
  • Based on sed facies which depend on sed support mechanisms, flow viscosity, water content, turbulence, material strength
  • Ternary plot with viscous to non-viscous, Turbulent to no turbulence, Cohesive plastic to cohesionless flow
74
Q

Name some evidence to distinguish mass wasting deposits from similar sed types (glacial till, fluvial)

A

Roundedness:
- Landslide angular, flacial moderate rounded, fluvial rounded
Internal Forms:
- Landslide transverse ridges, glacial sinuous moraines, fluvial lacks ridges
Sorting:
- Landslide very poor, glacial very poor, fluvial variable and generally good

75
Q

What are the 5 main morphological classifications?

A
  • Falls
  • Topples
  • Slides (translational, rotational)
  • Spreads (Lateral)
  • Flows (debris, earth, etc.)
  • Combinations are common
  • Consist of bedrock, sed, or both
76
Q

Rockfalls

A
  • Free or bounding downslope movement of loose rock material under influence of gravity
  • Begin with detachment of rock from a steep slope along a surface on which little or no shear displacement takes place
  • Materials bounce and roll once they impact lower gradient slopes
  • Primary process leading to development of talus/scree
  • Fall at 90 degrees, bounce at 70, roll less than 45 degrees
77
Q

Why do rockfalls and talus coarsen downslope?

A
  • Coarsens downslope b/c larger particles have more momentum and move further and crush upper sediments finer on their way down
78
Q

What are main triggers of Rockfalls?

A
  • Freeze-thaw, Earthquakes, Extreme precipitation

- Common on highway undercuts

79
Q

What are used to mitigate rockfalls on highways?

A
  • Fences
  • Work for individual rocks but not substantial falls
  • Also support walls and bolts
80
Q

Talus (scree) cones

A
  • Specific type of colluvium
  • Product of gravity driven mass movements that form at the bottom of rockfall dominated slopes
  • Shape dictated by angle of repose of debris composing them
  • Mostly angular, irregular rock fragments
  • Distal coarsening from fall sorting
  • Downslope trajectories vary with surface properties (roughness) and rock properties
81
Q

What happens to equidimensional boulders vs. oddly shaped boulders?

A
  • Roll and bounce vs. wedge or break on impact
82
Q

What does the degree of distal coarsening depend on?

A
  • Clast size, shape, lithology (hardness)

- Surface roughness (frictional resistance, depends on size of clasts and surface irregularities like veg)

83
Q

What is a positive feedback of talus cones?

A
  • Large boulders get trapped in large holes

- and in turn create more surface roughness to trap more boulders

84
Q

Why does Talus generally fine with depth?

A
  • Fines infiltrate into matrix
  • Large rocks have more momentum and roll further downhill
  • Upper sediments crushed by rocks rolling over them
85
Q

Topples

A
  • Forward rotation outward from slope
  • Axis of rotation below centre of gravity of displaced mass
  • Generally in rocks with steeply dipping discontinuities
  • Rotational stability of a particular block depends mostly on its aspect ratio (height to thickness) and angle
86
Q

Block Toppling

A
  • Common form of toppling

- Brittle failure flexural toppling occurs by plastic bending of weak rocks such as phyllite

87
Q

Which topples more easily, slender or cubic blocks?

A
  • slender
88
Q

Slides

A
  • Movement of soil, sed, or rock mass along a failure plane with relatively thin zones of intense shear
  • Determined by geology/stratigraphy (material type, permeability, shale, or clay layers, top of permafrost etc.)
89
Q

What are the 2 main categories of slides?

A
  • Translational

- Rotational

90
Q

Translational Slide

A
  • Planar rupture and slip face, no steps
  • Surface roughly parallel to the ground surface and often shallow
  • Shallower and longer than rotational slide
91
Q

Rotational Slide (slump)

A
  • Rupture along a concave (curved up) surface
  • Rotation lowers the head and raises the toe
  • Step-like features, back-tilted trees towards scarps, sag ponds on scarps
  • Stratigraphy maintained usually
92
Q

What is the surface morphology of a rotational slide characterized by?

A
  • Steep scarp
  • Flat upper surface
  • Stair-step effect created by multiple events
93
Q

Velocity profile of slides

A
  • linear with depth where all depths are moving at the same speed
  • Pure slides have little internal deformation
94
Q

Rotational Slides (Slumps)

A
  • Slower failure of massive blocks (usually sediment)

- Curved (rotational) failure planes often stepped (retrogressive)

95
Q

Rotational Slides (Slumps), Causes/triggers

A
  • Moisture effects (Precipitation)
  • Under cutting
  • Over steepening, undercutting
  • Loading
  • Logging
  • ## Vibration (EQ’s)
96
Q

Overstepping And Slumping

A
  • Slopes naturally achieve balance with forces acting on their mass by adjusting slope angle
97
Q

La Conchita, Ca

A
  • Rotational landslide
  • Rain instigated, pore pressure increase over rainy winter
  • Geomorph indicated historical landslides evident, why put a town there?
  • Happened again 10 years later, killed people, rain instigated again, Why no drain pipes?
98
Q

La Conchita, Ca

- Evidence of instability?

A
  • Many old slides
  • Extensive gullying on marine terraces above town
  • Large ancient scarp above modern failure indicated very large past events
99
Q

Bank Slump Failure

A
  • half way between translational and rotational
100
Q

Lateral Spread

A
  • Extension of a cohesive mass overlying deformable material
  • Fractured cohesive material often subsides into the softer flow
  • Trigger sets off deformable layer to move and upper firm layer ‘goes along for the ride’
  • May occur on gentle slopes
  • Spreads result from liquefaction, after EQ’s, and when sandy units overlie deformable clays
  • Common in areas of quick clay
101
Q

Quick clay landslide characteristics

A
  • Landslides retrogressive (slide motion itself triggers more failures and often dams rivers- Range from 10m^3 to 10^6m
  • arcuate or bottleneck shaped
  • Rotated blocks of overburden common
  • Overlying sands often shallow water facies
  • Underlying clays deeper water seds
  • Triggered by small disturbances (excavation, river erosion, small EQ’s)
102
Q

Quick clay

A
  • Salty, randomly stacked clay particles

- When salt leaches out and then vibration occurs the structure will liquify and flow

103
Q

Debris Flows

A
  • Viscous movement of soil and/or weathered bedrock
  • Internal shear deformation (velocity variance along the flow profile of the viscous fluid)
  • Includes mudflows, debris flows, earth flows, Lahars (volcanic), and some rock/debris avalanches
  • Range in size form a few m^3 of sand down a dune face to collapse of several km^3 from volcano
  • Common in BC
104
Q

Characteristics of debris flows

A
  • A form of rapid mass movement in which loose soil, rock, organic matter (logs), air, and water mobilize as a slurry and flow downslope
  • Between water and sediment flow
  • Rapid, depends on rheology of flow materials
  • Occur in variety of climatic and physiographic zones
  • Removal of trees increases infiltration capacity of water, need drainage to mitigate
105
Q

What are debris flows typically initiated by?

A
  • rapid addition of water by extended rainfall, localized areas of intense rainfall, ponding on surface upstream flow, snowmelt or rain on snow
106
Q

What are the most damaging mass movements in BC year after year?

A

Debris Flows

107
Q

Phases of Debris Flows?

A
  • Phase 1: Snout is composed of coarse material brought to the front by kinematic sorting (shaking)
  • Phase 2: Less viscous, main part of flow composed of sediments that are finer than the snout
  • Phase 3: Highest on slope, usually finest material
108
Q

Debris flow deposits

A
  • Often ungraded or normally graded (coarsest seds on the bottom
  • Stacked sequences of normally graded flows give frequency and recurrence interval
109
Q

Anatomy of debris flow channel?

A
  • Bare channel sides in upper reaches b/c of intense scouring produced when flow descends through a gully
  • Sometimes only base is bare and sides are still mantled w/ unconsolidated materials
  • Lower down w/ reduced slope gradient lateral ridges of coarse material levees b/c of friction along sides
  • Lateral ridges channel remainder of debris, increasing flow depth and velocity
  • Front is coarse grained snout
110
Q

What are the implications of pulsating habits of debris flows?

A
  • Affect the sedimentology of the deposit and the ability to measure frequency of events
111
Q

Debris flow Prerequisites?

A
  • Abundant water (extended or intense precip, ponding, rapid snowmelt, rain on snow)
  • Abundant fine seds (volcanics, glacial seds)
  • Slopes steeper than 15 degrees
112
Q

Geomorphic evidence of debris flow deposits

A
  • Lobate margins, convex surface
  • Coarse clasts at snout and sides
  • Surfaces studded with boulders
  • Flow levees
  • Boulders, logs in lower part
  • No gravel imbrication
  • Consolidated sed packed into nooks and crannies
  • Bare channels at top with increasing debris thickness downslope
  • Muddy coatings on boulders, logs etc.
113
Q

HCF

A

Hyperconsolidated Flow

114
Q

Largest slide in Canadian History?

A
  • Mount Meager 2010
  • Lahar
  • 13km runout, 270m runup
  • Dammed lake burst
  • Debris flow 65km downstream
  • Seismic equivalent of M2.6
  • Lilloet river morphology changed due to sed load increase
115
Q

Earth Flows

A
  • Mass movements of relatively dry, fine-grained materials
  • More sediment rich and slower than most debris flows
  • Typically exhibit both sliding and flowing
  • May be long-lived features, with movements occurring intermittently (decadal)
  • High viscosity flows, dry, slow
116
Q

Lemieux landslide

A
  • Geomorphology success story
  • Small 1971 landslide initiated study of glaciomarine clays
  • Indicated town was in danger zone so it was abandoned
  • 1993 rapid earth flow consumed farmland adjacent to town, no lives lost
  • Don’t need large slopes for extensive failure
117
Q

Creep

A
  • Upward heave with downslope (plastic) displacement
  • Flow is not rapid, very slow
  • Most widespread and poorly understood process
  • Associated with ‘heave’ (periodic expansion and contraction of a soil or sediment that is usually linked to clay swelling and dewatering or freeze/thaw)
  • Frost heave special consideration in Canada
  • Look for bending trees
118
Q

Why is frost heave important and how does it work?

A
  • Process that contributes to creep
  • Frost wedging acts perpendicular to the ground surface resulting in individual particles moving outwards from slope,
  • Melt causes gravity to bring material vertically downwards, not back where it came from on a slope
  • Net movement is downslope
119
Q

How can creep be significant?

A
  • Compress and wrinkle cas pipelines
120
Q

Solifluction

A
  • Creep in saturated beds
  • Slow gradual downslope movement of saturated sed lobes
  • Common in permafrost envrs
  • Permafrost impermeable to water so soil above saturates and moves slopes as shallow as 0.5 degrees
121
Q

Oso, Wa

A
  • Large late winter rainfall
  • No EQ
  • Logging in upper watershed
  • River undercutting
  • Glacial seds (marine clays)
  • Saturated above impermeable layer, very permeable sands above, increased pore pressure
  • Rotational slide that morphed into moist debris flow
  • Very dangerous for rescue workers, kept sinking on top
  • Dammed river, caused major flooding
  • Geomorphic evidence for past slides evident in lidar
122
Q

Mitigation examples

A
  • Geomorphic slope hazard maps
  • Geomorphic Monitoring programs
  • GPS surveys of monuments on colluvial aprons (but expensive)
  • Corner reflector interferometric synthetic aperature radar (Crinsar) for repeat measurements form space of coherent targets established on colluvial aprons (detect mm scale movement)
123
Q

Geomorphic slope hazard maps

A
  • Map past failures, evidence of current or incipient slope movement, slope materials prone to failure, slope angles etc.
  • Develop setback-distance maps
  • eg slope plane map of NEBC
124
Q

Slope plan map NEBC

A
  • Hazard map based on local relief and proximity to rivers
  • Hazard parameters based on sed characteristics and empirical data on historical failures
  • Slope planes > 7 from toe to surface
  • Zones created btwn valley side where slope plan represents an area where slope movement could occur
  • Distribution of previous failures mapped from geomorphic data
125
Q

Geomorphic monitoring programs

A
  • What are typical velocities
  • When is most likely to occur
  • Can climate variables correlate to events
  • eg Colluvial apron monitoring program NEBC
126
Q

Colluvial Aprons

A
  • Area accumulations of bedrock and/or sediments below cliffs or escarpments, convex or concave upper surface
  • silt and clay-rich matrix, high water table (pore water pressure)
  • Common, found on valley sides, river valleys, and upland escarpments
  • Associated w/ continuous, low-mag, down-slope movement
127
Q

Mitigation for pipelines in danger zones

A
  • Put pipe on slip plates so ground can slide under pipeline
128
Q

Synthetic Aperature Radar (SAR)

A
  • RadarSat-1
  • C-band wavelength (5.6 cm)
  • Orbit every 24 days
  • Non-intrusicve, non-destructive
  • Precise, reliable, cost-effective
  • Permits pro-active attention to instability
  • Enables retroactive analysis back to 1992
  • Reflectors on cliff top bedrock to provide datum, representative colluvial aprons and pipeline corridors
129
Q

What are the forms of mass wasting most characterized by?

A
  • Materials
  • Moisture
  • Speed of failure
130
Q

Strength and Stress most controlled by?

A
  • Moisture/hydrology
  • Sediment properties
  • Slope
  • Land use

Geog375Gmphlgy (9 decks)

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