Learning Objectives

1
Learning Objectives

• Meaning of Environmental Geology
• Scientific Method
• Cultural/Environmental Awareness
• Environmental Ethics
• Environmental Crisis?
• Sustainability
• Systems Environmental Unity
• Uniformitarianism

2
Environmental Ethics

• What does this mean?
• Environmental consciousness
• Existence of relationships between the physical
  environment and civilization
• Motivation for concept? e.g., The Quiet Crisis
• Land Ethic Responsibility to the total
  environment as well as society
• Meaning / scope?
• Limits?
• Perspective

3
Environmental Crisis

• Meaning?
• Increasing demands on diminishing resources
• Demands accelerate as the population grows
• Increasing production of wastes
• Factors
• Overpopulation
• Urbanization
• Industrialization
• Low regard for environmental/land ethics
• Inadequacy of institutions to cope with
  environmental stresses

4
Fundamental Concepts

1. Population Growth
2. Sustainability
3. Systems
4. Limitation of Resources
5. Uniformitarianism
6. Hazardous Earth Processes
7. Geology as a Basic Environmental Science
8. Obligation to the Future

5
Eight Fundamental Concepts

• 1. Overpopulation 1 environmental problem
• 2. Environmental objective sustainability
• 3a The earth is (essentially) a closed system
  with respect to materials
  
• 3b Solutions to environmental problems require
  understanding of feedback and rates of change in
  systems
• 4a. The earth is the only sustainable habitat we
  have
• 4b. Its resources are limited
• 5. Todays physical processes are modifying our
  landscape (and environment), and have operated
  throughout geologic time but magnitude and
  frequency are subject to natural and man-induced
  changes
• Earth processes that are hazardous to people have
  always existed
• An understanding of our environment requires an
  understanding of the earth sciences (and related
  disciplines)
• The effects of land use tend to be cumulative.
  Thus, we have an obligation to those who follow
  us.

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Systems

• System Any part of the universe selected for
  study
• Concept of systems
• Earth as a system (w/ component systems)
• Atmosphere (air)
• Hydrosphere (water)
• Lithosphere (rock, soil)
• Biosphere (life)
• Interactions of these parts conditions of the
  environment
• Changes in magnitude or frequency of processes in
  one part causes changes in other parts, e.g., ?

7
System Feedback

• Negative System adjusts to changed conditions to
  reestablish steady state, e.g., river
• Positive Changes in a system that cause
  significant modifications of a system, and result
  in amplification of the changes

8
Uniformitarianism

• The past is the key to the present
• We can gain understanding of geologic processes,
  systems, etc. in the past by understanding how
  they work today
• Examples
• Mountain building/topography/landscape
• Erosion
• Water cycles
• Climate
• Relationships between life environment

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Uniformitarianism cont

• Key concept in interpreting geologic
  observations, e.g.,
• Glacial processes
• Marine fossils on mountain tops
• Volcanism elsewhere in the solar system
• Ore, petroleum deposits
• Key for using geologic knowledge to understand
  natural earth processes in historical and
  predictive modes

10
Chapter Summary

• Environmental Geology ?
• Consideration of time in geologic sciences
• Cultural basis for environmental degradation
  (explain)
• Ethical
• Economic
• Political
• Religious
• Environmental problems not confined to any one
  political or social system
• Land ethic ?
• Immediate cause of environmental crisis
• Overpopulation
• Urbanization
• Industrialization
• (what do these mean whats the relationship?)

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Chapter Summary cont

• Environmental Problems mean what?
• Solutions to environmental problems require what?
• Scientific understanding (of what?)
• Fostering social, economic, and ethical behavior
  to allow implementation (Explain)

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Earth Materials Processes

• Focus
• Geologic materials and processes most important
  to the study of the environment
• Objectives
• Acquire a basic understanding of the geologic
  cycle and its subcycles (tectonic, rock,
  hydrologic, biogeochemical)
• Review of some of the important mineral and rock
  types and their environmental significance
• Appreciation/significance of geologic structures
• Appreciation of the landforms, deposits, and
  environmental problems resulting from wind and
  glacial processes

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• Observations/Correlations
• Types and spatial distribution of plate
  boundaries
• Correlation between plate boundaries and
  volcanoes ( earthquakes)

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Two Types of Crust/Lithosphere

• Oceanic (O)
• forms 70 of earths crust
• constitutes sea-floor bedrock 30 km thick
• made of primary volcanic basalt
  density2.7-3.0
• Young No old oceanic crust
• Continental (C)
• Thicker (100 km)
• Composition Less dense sediment/granite
• floats on denser mantle material
• Older
• Mantle
• Primary material (from which basalts are derived)
• Underlies crust

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Main Types of Plate Boundaries

• Divergent (splitting apart)
• Convergent (colliding)

• Third Type Transform (e.g., lateral offset)

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Types Plate Motion, Plate Boundaries, and
Examples of Associated Landforms/Features

• Divergent (separating)
• O-O sea-floor spreading/mid-ocean ridges
• C-C Continental rifts Red Sea, Rio Grande
  Mississippi river valleys, E. African (Kenyan)
  Rift Valley
• Convergent (colliding)
• O-O Island arc Subduction Japan, Aleutians
• O-C Continental margin Subduction Cascades,
  Andes
• C-C Continental collision Himalayas, Alps,
  Appalachians
• Others Obduction Accreted terrain

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Other Important Types/Features

• Hot Spots
• Hawaiian Islands
• Yellowstone, Snake River Plain, Columbia River
  Plateau
• Flood Basalt Provinces (within continents)
• Columbia River Basalts
• India, S. Africa, Greenland, Brazil, Germany,
  etc.

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Hydrologic Cycle
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Summary

• Earth is differentiated and dynamic
• Manifestation of dynamic earth processes in
  lithosphere plate tectonics
• Two types of crust oceanic continental
• Centers/Zones where crust is formed (spreading)
  or destroyed (subducted) or accreted define plate
  boundaries
• Two types of plate boundaries
• Divergent (splitting/spreading)
• Convergent

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Chapter (Section) Objectives

• Review of some of the important mineral and rock
  types and their environmental significance
• Relationships between atoms, minerals, rocks,
  rock materials
• Basic silicate building block(s)
• Properties of rocks minerals
• Basic rock types, basis for classification,
• Why this stuff is important the types of
  information they provide
• Appreciation/significance of geologic structures
• Layering
• Folds
• Faults
• Other structures (joints, dikes/sills, etc.)

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• Rock
• A solid, cohesive aggregate of grains of one or
  more minerals
• Mineral
• Naturally occurring crystalline inorganic
  substance with a definite chemical composition
  element or compound with a systematic arrangement
  of atoms / molecular structure (e.g., sulfur,
  salt, silicates such as feldspar)
• Crystallinity
• Atomic arrangement imparts specific physical and
  chemical properties
• Physical properties of minerals
• color, hardness, cleavage, specific gravity,
  streak, etc.

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• Relationship between
• Atoms
• Molecules
• Minerals
• Rocks
• Landforms

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Rock Strength Stess-Strain Relationships
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Relationship between Rock Types and Plate
Tectonics
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• Rock Cycle- Cycle of melting, crystallization,
  weathering/erosion, transportation, deposition,
  sedimentation, deformation metamorphism, repeat
  of crustal materials.

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Classification of Igneous Rocks By Physical
Criteria
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Types / Classification of Sedimentary Rocks

• Clastic Formed from the mechanical and/or
  chemical weathering of other rock materials
• Sandstone, shale
• conglomerate
• Chemical Formed as inorganic precipitates (i.e.,
  water saturated with respect to chemical
  compounds)
• Limestone (Ca-carbonates (caliche)
• Other salts, e.g., sulfates, hydroxides, halogen
  salts (e.g., NaCl)
• Silica
• Organic Formed from (and including) organic
  material such as
• Fossil materials (typically shells, diatoms,
  etc.) exoskeletons, or endoskeletons of aquatic
  (e.g., marine) organisms
• Organic and/or chemical cements (carbonate,
  silica, phosphates)
• Combinations
• e.g., Clastic or organic sediment with chemical
  cement

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Significance of Rock Types to Environmental
Geology

• Type and origin or rock provides insight into
  present or past environmental conditions (e.g.,
  flood deposits, volcanic mudflows)
• Differences in rock types can have important
  environmental implications (e.g., strata/layers)
• Physical Properties
• Strength
• Planes of weakness
• Porosity, permeability
• Chemical Properties
• Tendancy to dissolve (solubility), leach, or react

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Examples

• Limestone
• Typically formed in a reef or deep marine setting
• Highly stable in arid climates, unstable in wet
  climates
• Poor aquifer material
• Highly conducive to formation of ore deposits
  when adjacent to igneous magams or hydrothermal
  fluids
• Implications for finding them in high mountains?

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Examples cont

• Sandstone
• Formed as near-shore marine and desert
  environments (w/ noteable differences)
• Moderate strength
• Generally porous and permeable
• Foliated Metamorphic Rocks
• Implies formation under conditions of directed
  tectonic forces
• Have potential planes of weakness
• Others (See charts/figures)

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Types of Geologic Structures

• Stratification (Layers Layering)
• Folding/Tilting
• Faulting
• Other Structures
• fractures
• joints
• crosscutting from forceful injections
  (dikes/sills)

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Significance of Layering/Tilting

• Basic geologic structure
• Planar reference boundaries that define strata
  (boundaries between/within rock materials)
• Implications for landforms/topography?
• Potential pathways

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Significance of Fault Folds

• Areas of broken and/or disrupted crust
• Usually associated with topographic features
• Usually results in exposure of different types of
  rock materials at surface
• Indicative of past and/or present forces
• Potential for environmental hazard?
• Often associated with natural resources
  (minerals, petroleum, etc.)
• Effects on fluid pathways (as preferrential
  pathways or barriers)

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Other Structures

• Fractures
• Joints
• Crosscutting material from forceful injections
• Dikes (cross-cuts layering)
• Sills (parallel to layering)

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Summary / Review

• Building blocks of rock materials atoms,
  molecules, minerals, rocks/rock materials
• Most abundant minerals are silicates
• Basic building block is the silica tetrahedra
• Rock properties determined by properties of
  component materials (minerals)
• Three main classes of rocks
• Igneous Formed from molten material
• Sedimentary Clastic, chemical, organic,
  combinations
• Metamorphic foliated, non-foliated

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Summary / Review

• Rock type provides various types of information
• Environment/setting in which they were formed
• Tectonic implications
• Implications for natural hazards
• Physical, chemical properties
• Etc.
• Geologic Structures
• Layering, tilting
• Folding
• Faulting
• Other types (fractures, jointing, cross-cutting
  features)
• Implications/significance of geologic structures

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Learning Objectives

• Soils terminology processes
• Interaction of water in soil processes, soil
  fertility
• Classification of soils (familiarity)
• Engineering properties of soil
• Relationships between land use and soils
• Sediment pollution
• Desertification

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Roles of Soils in the Environment

• Land use planning (suitability)
• Soil erosion
• Agriculture
• Waste management (interactions between waste,
  soil, water)
• Natural hazards land use planning in terms of
• Floods
• Landslides, slope stability
• Earthquakes

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Soil Formation

• Soil formation begins with weathering
• Weathering Physical and/or chemical breakdown
  of rocks (open system)
• Physical (mechanical) Processes Big ones to
  little ones
• Abrasion
• thermal (expansion/contraction)
• frost wedging
• Chemical Processes Dissolution (congruent,
  incongruent w/residue)
• Soil Formation depends on
• Climate
• Topography
• Parent material
• Time/age of soil
• Organic processes

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Soil Profile Development

• Variables
• Parent material
• Climate
• Topography
• Time (Soil age / extent of development)
• Organic activity

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Soil Horizons
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Climatic Effects on Soil Formation
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Land Use Other Soil Problems

• Human activities affect soils by influencing
  patterns, amounts, and intensity of
• Surface-water runoff
• Erosion
• Sedimentation
• Conversion/manipulation of natural areas
  surface water
• (see Figures 3.12, 3.13)

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Land Use Other Soil Problems

• Urbanization
• Off-Road Vehicles
• Soil Pollution
• Desertification
• Others

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Corrective Measures

• Erosion Controls
• Terracing, contour stripping
• Vegetation barriers
• Water/sediment basins/reservoirs
• Characterization planning
• Pollution abatement
• Treament, e.g., bioremediation
• Others?

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Summary/Overview

• Definitions of soil
• Roles of soils in environmental geology
• Land use planning
• Waste disposal
• Evaluation of natural hazards
• Formed from rock interactions in the hydrologic
  cycle (explain)

• Variables (explain)
• Climate
• Topography
• Parent material
• Time
• Organic activity
• Soil processes form distinctive layers (horizons)
• Soil Properties
• Color
• Texture (particle size)
• Structure (peds)

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Learning Objectives

• Conditions that make some natural processes
  hazardous
• Benefits of hazardous natural processes
• Types of natural hazards
• Prediction of natural disasters
• Perception and adjustments to natural hazards
• Impact and recovery from natural disasters and
  catastrophes

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Natural Processes as Hazards

• Natural hazards Natural processes
• Types/examples
• Earthquakes
• Rivers flooding
• Mass movement (e.g., landslides, mudslides,
  avalanches)
• Volcanic activity
• Coastal hazards
• Others
• Cyclones, tornados, hurricanes
• Lightning
• Radon
• Etc.

?
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Benefits of Natural Hazardous

• Natural hazards that have benefits
• Flooding
• Landslides
• Volcanism
• Earthquakes
• Explain

?
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Risk Assessment

• Risk Probability x Consequence
• E.g., risk of death from smoking cigarettes
• Consequence Death (could be other effects)
• Probability Frequency of this consequence in a
  population
• Must be calculated for various scenarios/events,
  e.g., earthquake of various magnitudes, proximity
  to population centers, structures (nuclear plant,
  dam)

?
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Acceptable risk

• There is risk associated with everything
• There is no such thing as zero risk, only
  different levels of risk
• e.g., Everyone is exposed to risks everyday
  (e.g., driving, radon)
• Levels of Acceptable Risk are, therefore,
  established
• Examples of Acceptable Risk Levels are used in
  toxicology human health risk assessments
• e.g., Increased acceptable risk from exposure to
  cancer-causing chemicals is typically 10-6 (risk
  of death from natural levels of radon 10-3 )
• What do these numbers mean?

?
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Relationship Between Hazards and Climate Changes?

• System interrelationships or feedback of annual
  weather and/or climate changes?
• E.g., El Nino, La Nina, others
• Global warming?
• Connections between weather/climate and
• Storms
• Fires
• Floods
• Drought (hydrologic cycle)
• Food supply (fishing to agriculture)
• Energy (e.g., demand vs. hydroelectric supply)
• etc. (See Text Chart)

?
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Population, Land-Use and Natural Hazards

• Effects of Population Increase
• Proximity issues (e.g., quakes, volcanoes,
  floods)
• Cause effect issues(Mexico City example)
• Changing Land-Use Effects
• Disruption of natural system buffers
• Changed/exacerbated feedback
• Examples
• Yangtze River flooding
• Hurricane in Central America
• Reasons?

?
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Learning ObjectivesRivers Flooding

• Appreciation for river processes
• Flood hazard
• Nature extent
• Upstream vs. downstream flooding
• Effects of urbanization (in small drainage
  basins)
• Main preventive adjustment measures
• Environmental effects of channelization

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Main Topics

• River Systems/Processes
• Features Landforms
• Flooding
• Factors
• Prevention
• Case Studies

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Sediments in Rivers

• Load Quantity of sediment carried in a river
• Bed load moved along bottom
• Suspended load carried in suspension
• Dissolved load in solution

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Slope Profiles

• Slope or gradient
• vertical drop /horizontal distance (e.g.,
  km/km)
• Gradient angle tan-1 (gradient)
• e.g., for gradient of 0.01, tan-1 (0.01)0.5o
• Longitudinal profile
• Graph of elevation vs. distance downstream

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Key Parameters RelationshipsContinuity Equation

• Discharge (m3/sec)
• Q volume of water passing a point per unit
  time
• Velocity (m/sec)
• Cross-sectional area (width x depth) (m2)
• Q v x W x D
• (At constant slope)

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Key Parameters RelationshipsStream Power
Capacity

• Stream Power (P) ability to transport and/or
  erode sediment
• P Q x slope x r where r 10-5 kg/m3 units
  of P (kg/sec)
• P velocity x width x depth x slope x density
• i.e., - narrower, shallower streams, have higher
  velocities erode
• - wider, deeper streams, have lower
  velocities deposit
• - Steeper gradients, higher velocities, erode
  vice-versa
• Capacity total load that can be carried/time
  (e.g., kg/sec)
• Competence largest particle (diam.) a river may
  transport

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Balance (equilibrium) between deposition/erosion
as function of D (Q, velocity, etc.)

• Along the longitudinal profile (headwaters vs.
  downstream)
• Pools
• Riffles
• Bars

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Balance (equilibrium) between deposition/erosion
as function of D (Q, v, x-sect. dimensions, etc.)

• In response to land-use changes (e.g., dams)

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Balance (equilibrium) between deposition/erosion
as function of D (Q, v, x-sect. dimensions, etc.)

• Flooding (general)
• Floodplains features

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• Upstream floods
• Intense rainfall
• Of short duration
• Over relatively small area
• E.g., flash floods
• Downstream floods
• Cover a wide area
• Produced by storms of long duration
• Saturated soil ? increased runoff
• Contribution from many tributaries
• E.g., regional storms, spring runoff

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Factors That Affect Flooding

• Rainfall (weather) events
• Local vs. regional
• Seasonal
• 50, 100-year floods
• Runoff (factors affecting infiltration)
• Gradient
• Vegetation
• Human effects
• Urbanization (e.g., paving, storm sewers)
• Others?

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Flood Damage Prevention/ Control

• Physical barriers
• Levees/bank stabilization
• Dams
• Retention ponds
• Floodplain regulation
• Optimizing floodplains w/ minimal flood damage
• Balance of natural resource w/ natural hazard
• Zoning
• Diversion channels/reservoirs
• River management (plans to minimize bank erosion,
  etc.
• Flood hazard mapping
• Channelization

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Channelization

• Engineered modification of stream channels
• Straightening
• Deepening
• Widening
• Clearing
• Lining
• Objectives
• Flood control
• Drainage
• Erosion control
• Improved navigation

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Pros Cons of Chanelization

• Pros (Benefits)
• Same as objectives where benefits outweigh
  environmental damage/degradation

• Cons (Adverse Effects)
• Environmental Degradation
• Wetland drainage
• Vegetation elimination/decrease
• Habitat effects
• Erosion, siltation
• River flow pattern effects
• Aesthetic effects

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Learning Objectives

• Gain a basic understanding of slope stability and
  mechanisms of slope failure
• Understand the role of driving and resisting
  forces affecting slope stability
• Understand factors that affect slope processes
• Topography
• Climate
• Vegetation
• Water
• Time
• (Gravity)
• (rock type)
• Understand how human use of land affect
  landslides slopes
• Familiarization with identification, prevention,
  warning, correction of landslides
• Appreciation for processes related to land
  subsidence (Part B)

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Slope Stability

• Relationship between driving resisting forces
• Driving forces (DF)
• Weight of rock, soil
• Weight of superimposed material
• Vegetation
• Fill
• Buildings
• Resisting forces (RF)
• Shear-strength of slope material acting along
  potential slip planes
• Cohesion
• Internal friction
• Ratio RF/DF Factor of Safety (FS)
• gt1.0 stable
• lt1.0 unstable
• Subject to changed conditions (see example fig.
  6.4)

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Causes of Landslides

• Real Causes
• Driving Forces gt Resisting Forces
• Immediate causes (triggers)
• Earthquake shocks
• Vibrations
• Sudden increase in water
• External Causes
• Slope loading
• Steepening
• Earthquake shocks
• Internal Causes Causes that reduce shear
  strength

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Functional Relationships

• Relationship between downward force (gravity)
  Resistance force (shear stress)
• Stress force / unit area
• S shear stress
• S C (p-u) tanq p total pressure
• u fluid pressure (pore water
  pressure)
• tan q coefficient of internal
  friction
• q angle of internal friction
  (frict. resist.)
• S C (sn -u) tanq sn normal stress (i.e.,
  normal to surface
• or plane of discontinuity
• C cohesion of material

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Factors/Controls

• Gravity
• Weight (force) downslope component of the weight
  of the slope materials above the slip plane
• Downward
• Normal to surface or plane of discontinuity (sn)
• Parallel to surface or plane of discontinuity
• Angle of repose (slope angle)
• Slope and topography
• Water
• Rock Type
• Structure
• Others? (Anthropogenic)

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Factors Resulting in Decreased Slope Stability

• Increased pore pressure (affects sn) e.g.,
  Storms, fluctuating groundwater
• Increased water content (reduces C, q)
• Steepening of slopes (affects sn)
• Loading of slopes (affects sn)
• Earthquake shaking (reduces C, q)
• Removal of material from the base of slopes
  (Directly reduces S)
• Rivers, waves, man
• Changes in vegetation
• Change in chemical composition of pore water

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Roles of Rock/Soil Type

• Patterns of movement
• Rotational slides (slumps)
• occur along curved surfaces
• Produces topographic benches (see fig.)
• Commonly occur in weak rock types (e.g., shale)
• Translational slides
• Planar
• Occur along inclined slip planes within a slope
  (6.2)
• Fractures in all rock types
• Bedding planes in rock slopes
• Clay partings
• Foliation planes (metamorphic rocks)
• Soil Slips
• Type of translation slide
• Slip plane above bedrock, below soil
• Colluvium

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Role of Climate Vegetation

• Controls nature/extent of ppt., moisture content
• Vegetation effects (dependent on plant type)
• Enhances infiltration/retards erosion
• Enhanced cohesion
• Adds weight to slope
• Transpiration reduces soil moisture

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Minimizing Landslide Hazards

• Identification of potential landslides
• Prevention of Landslides
• Drainage controls
• Grading
• Slope supports
• Warning systems
• Landslide correction

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Causes of Landslides

• Real Causes
• Driving Forces gt Resisting Forces
• Immediate causes (triggers)
• Earthquake shocks
• Vibrations
• Sudden increase in water
• External Causes
• Slope loading
• Steepening
• Earthquake shocks
• Internal Causes Causes that reduce shear
  strength

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Subsidence Learning Objectives

• Understand the types of subsidence and the causes
  of each type
• Key controls of subsidence processes, and
  mitigation
• Human effects that promote or mitigate subsidence

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Types of Subsidence

• Subsidence at or near the surface (Volume
  losses)
• Withdrawal of fluids
• Underground Mining
• Dissolution of limestone or salt deposits

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Subsidence at or near the surface (Volume losses)

• Above compressible (fine-grained) sediments
• Associated with clayey soils
• Draining or decomposition of organic deposits

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Learning objectives

• Understand the relationship of earthquakes to
  faulting
• Familiarization with earthquake wave (energy)
  terminology
• Understand the concept of earthquake magnitude
  (and its calculation)
• How seismic risk is estimated
• Familiarization with the major effects of
  earthquakes
• The prediction of earthquakes
• Mitigation of earthquake damage

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Earthquake Processes

• Faults and Fault Movement
• Relationship to plate tectonics
• Geographic distribution
• Relationship to plate boundaries
• Shallow earthquakes
• Deep earthquakes

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Types of Plate Boundaries Seismicity

• Transform-Margin Earthquakes
• Intraplate Earthquakes
• Basin and Range Mid-Continent

• Divergent-Margin Earthquakes
• Convergent-Margin Earthquakes

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Seismic Waves and Ground Shaking

• Focus Point/area where rupture starts
• Epicenter point on earths surface directly
  above the focus

• Types of seismic waves
• Body waves waves travel within the earth
• P- waves Primary compression waves
• S- waves Shear waves
• Surface waves
• L-(Love) waves horizontal ground movement
• Rayleigh waves rolling motion

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Seismic Waves

• WavesForms of energy release
• Motion/propagation types
• Frequency Number of waves passing a reference
  point/sec
• Period Number of seconds between successive
  peaks
• Amplitude Measure of ground motion
• Attenuation/amplification

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Comparing/Measuring Earthquakes

• Magnitude
• Measure of energy released (log scale)
• measurement scale Richter scale (0-10)
• Intensity
• Relative scale based on perceived damage
• Modified Mercalli Scale (1-12)
• Ground acceleration during earthquakes
• Rate of change of horizontal or vertical velocity
  of the ground
• Normalized/compared to earths gravity 9.8
  m/sec2 1g
• e.g., M 6.0-6.9 quake ? 0.3-0.9 g

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Elastic Rebound Model
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Elastic Rebound
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Dilatancy-Diffusion Model/Fault Valve Mechanism
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Earthquakes Caused by Human Activity

• Reservoir-induced seismicity
• Deep waste disposal
• Nuclear explosions

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Effects of earthquakes

• Ground shaking and rupture
• Liquifaction
• Landslides
• Fires
• Tsunamis
• Regional changes in land elevation

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Earthquake Damage

• Buildings Swaying, Pancaking
• Broken pipelines (gas, water) electrical lines
• Fires explosions (from pipelines storage
  tanks)
• Shearing subsidence of sand fills
• Quicksand, sand boils, sand volcanoes
• Quickclays
• Landslides

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Origins of Tsunamis

• Sudden vertical displacement of seafloor (from
  dip-slip fault)
• Momentary drop in local sea level
• Water rushes into depression, but overcorrects,
  locally raising the sea level
• Sea level locally oscillates before stabilizing
• Oscillations are transmitted as long, low seismic
  sea waves

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Response/Prediction Options
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Response to Earthquake Hazards

• Earthquake hazard-reduction programs
• Earthquakes and critical facilities
• Societal adjustments to earthquakes
• structural protection
• land-use planning
• increased insurance and relief measures
• earthquake warning systems
• perception of earthquake hazard

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My Objectives

• How are they formed?
• How do they work?
• Where do they occur, and why?
• Main types of volcanic activity, eruptive styles,
  and products
• Volcanic landforms
• Volcanic hazards, prediction, mitigation
• Relationships

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Volcanism Correlations
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Relationships Between Plate Tectonic
Mechanisms,Volcanic Styles Products

• Basaltic magmas
• Derived from melting of mantle
• Ocean-ridge plume eruptions
• Magmas w/o crustal contamination
• More Si-rich magmas
• Involve melting of crust, and/or flux-melting of
  mantle from de-watered subducted crust
• Subduction-related
• Mid-continent eruptions w/ crustal contamination

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Classification by magma type

• Two main end-member types
• Basaltic (equivalent of gabbro)
• Rhyolitic (equivalent of granite)
• Other types
• Intermediate between basaltic and rhyolitic
  (andesitic)
• Exotic (alkaline)

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Volcanic Products

• http//www.geology.sdsu.edu/how_volcanoes_work/Hom
  e.html

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Volcanic Hazards

• Lava flows
• Pyroclastic (hot debris) Hazards
• Falls
• tephra
• ash
• pyroclastic (ash) flows
• explosive blasts
• Gases
• Debris Mud Flows
• Others
• http//magic.geol.ucsb.edu/fisher/hazards.htm
• http//volcanoes.usgs.gov/Hazards/What/hazards.ht
  ml

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Volcanic Products

• http//www.geology.sdsu.edu/how_volcanoes_work/Hom
  e.html

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Caldera Eruptions

• When an erupting volcano empties a shallow-level
  magma chamber, the edifice of the volcano may
  collapse into the voided reservoir, thus forming
  a steep, bowl-shaped depression called a caldera
  (Spanish for kettle or cauldron).

http//www.geology.sdsu.edu/how_volcanoes_work/Hom
e.html
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Volcanic Hazards

• Lava flows
• Pyroclastic (hot debris) Hazards
• Falls
• tephra
• ash
• pyroclastic (ash) flows
• explosive blasts
• Gases
• Debris Mud Flows
• Others
• http//magic.geol.ucsb.edu/fisher/hazards.htm
• http//volcanoes.usgs.gov/Hazards/What/hazards.ht
  ml

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Case Histories

• Nevado del Ruiz
• Mt. St. Helens
• Long Valley Caldera
• Mt. Pinatubo
• Mt. Unzen, Japan