Your original response should be at least 350 words The site t.docx

Your original response should be at least 350 words
The site that is recommended for #3 assignment is ProQuest for
picking an article.
#3
First, identify a peer-reviewed psychology journal article on a
topic of your choice. Read and reflect on the article. Write a
summary of the article, addressing the following in your
primary response:
· Provide a general overview of the article you selected.
· What were the main points of the article (e.g., for a research
article, summarize research questions, population, findings,
limitations, and recommendations for future study)?
· What type of scholarly article did you select (research article,
review article, theoretical article, or meta-analysis)?
· What keywords or indicators in the title, abstract, or article
helped you identify the type of scholarly article?
· Use proper APA formatting, including in-text citations.

Your original response should be at least 350 words
Read the text: Learning to Think Things Through: A Guide to
Critical Thinking across the Curriculum.”
#4
Reflect on the readings and your views of critical thinking.
Provide an analysis of what critical thinking entails and how
psychology professionals use it in their work. Be sure to address
the following in your response:
· What does critical thinking mean to you?
· Examples of critical thinking frameworks include the SEE-I
Method, Standards Check, and the Circle of Elements. Which
critical thinking frameworks will you use as a graduate student?
· How will you use critical thinking in your professional career?
· What are two impediments to critical thinking?
CH. 3 - EARTHQUAKES
https://www.usgs.gov/news/updat
e-magnitude-71-earthquake-

southern-california
https://www.usgs.gov/news/update-magnitude-71-earthquake-
southern-california
Learning Objectives
• Compare and contrast the different types of faulting.
• Explain the formation of seismic waves.
• Summarize the processes that lead to an earthquake and the
release of
seismic waves.
• Differentiate between the magnitude scales used to measure
earthquakes.
• Identify global regions at most risk for earthquakes, and
describe the
effects of earthquakes.
• Describe how earthquakes are linked to other natural hazards.
• Explain how human beings interact with and affect earthquake
hazards.
• Propose ways to minimize seismic risk and suggest
adjustments we can
make to protect ourselves.
Basic Fault

Features
Footwall
• Block below the fault plane
• Miner would stand here
Hanging wall
• Block above the fault plane
• Hang a lantern here
Faults ≠ Plate boundaries
• However, most faults occur along plate boundaries
• Fault types
- Distinguished by direction of rock displacement
• Three basic types:
1. Dip-slip
a) Normal
b) Reverse
2. Strike-slip
a) right-lateral
b) left-lateral
3. Oblique slip

Seismic Waves
• Caused by a release of energy from rupture of a fault
• Body waves: travel through the body of the Earth:
• P waves, primary or compressional waves
- Move fast with a push/pull motion
- Can move through solid, liquid, and gas
• S waves, secondary or shear waves
- Move slower with an up/down motion
- Can travel only through solids
Seismic Waves, cont.
Surface waves: move along
Earth’s surface
• P and S waves that reach the
surface
• Travel more slowly than body
waves
• Complex horizontal and vertical

ground movement
Rayleigh Waves
• Rolling motion
• Responsible for most of the
damage near epicenter
• Shaking produces both
vertical and horizontal
movement
Surface waves: move
along Earth’s surface
surface
waves
• Complex horizontal and
vertical ground movement
Love Waves
• Horizontal ground shaking
• Faster than Rayleigh

waves
• Do not move through water
or air
• Very hazardous!
Wave direction
Calculating Epicentral Distance
P wave has velocity VP ; S wave have velocity VS
VS < VP
Both originate at the same place – the hypocenter – and travel
the same distance, but
the S wave takes longer to arrive than the P wave.
Time for S wave to travel a distance D:
Time for P wave to travel a distance D:
The time difference between them is:
Now solve for the distance D:
Time =
Distance
Velocity
TS =

D
VS
TP =
D
VP
(TS -TP ) =
D
VS
-
D
VP
= D
1
VS
-
1
VP
æ
è
ç
ö
ø

÷=D
VP -VS
VPVS
æ
è
ç
ö
ø
÷
� =
��
�� − ��
�� − ��
Earthquake Shaking
• Shaking experience depends on:
1. Earthquake magnitude
2. Location in relation to epicenter and direction of rupture
3. Local soil and rock conditions
• Strong shaking from a moderate magnitude or higher

Fault Rupture
• Slip: displacement
between two rock
blocks
• Rupture area: surface
where rocks have
moved
• Both parameters used
in advanced magnitude
calculations because
related to the energy
needed to move large
blocks of rock
Earthquake Magnitude
Richter scale
• Not typically used anymore
• Recorded with a seismograph
- Measures maximum amount of ground shaking due to S wave
• Local magnitude
- Depends on where it is located
- Specific to only one location

• For events with shallow hypocenters that are located less than
500
km from seismograph stations
• Based on idea that the bigger the earthquake, the greater the
shaking of the Earth
Is this always true though??
Photo credit: SSA
Richter Scale – Local earthquake magnitude (ML)
• For local earthquakes in Calif.
• Recorded on Wood-Anderson.
• ML = log A(mm) + 3 log[R] – 2.92
• Reference :
• Should expect Amplitude of 1 mm
• At Distance of 100 km
• From ML=3
Use the above equation or the graphical
method
• Three vertical axis; R (or S-P), M, A
• Measure (S-P)
• Find R : R= 8(S-P)

• Mark R on R vertical axes
• Measure A, mark on axis
• Draw a line between two marks
• Obtain M
Example:
• Amplitude = 23 mm
• S-P time = 24 s
• Thus Ml=5
Earthquake Magnitude
• Richter scale
- Not typically used anymore
- Recorded with a seismograph (or seismometer)
• Measures maximum amount of ground shaking due to S wave
- Local magnitude
• Depends on where it is located
• Specific to only one location
• Moment magnitude scale
- Absolute size of earthquake (compare multiple locations)
- Measurement of actual energy released

• Determined from area of rupture, amount of slippage, and the
rigidity of
the rocks
- Estimates can take days to calculate
Seismic Moment
• Current method of measuring earthquake size
• Relies on the amount of movement along the fault that
generated the earthquake
Where A is the fault area (W x L), μ is the shear modulus
(rigidity) and D is the amount of slip
Units of
or
[N ×m]
[dyne ×cm]
M0 = mAD
Total Slip in the M7.3 Landers Earthquake
Rupture on a Fault

Moment Magnitude
• Magnitude scale that uses the seismic moment of an
earthquake
• More accurate for large earthquakes since it is tied to the
physical parameters of the fault such as rupture area, slip
and energy release
• Measures amount of energy released by the movement
along the whole rupture surface
MW =
2
3
log(M0 )-6.1 No units!
Global Frequency of Earthquakes
Descriptor Average Magnitude Annual Number of Events
Great 8 and higher 1
Major 7–7.9 14
Strong 6–6.9 146

Moderate 5–5.9 1344
Light 4–4.9 13,000 (estimated)
Minor 3–3.9 130,000 (estimated)
Very Minor 2–2.9
1,300,000 (estimated)
(approx. 150 per hour)
Source: U.S. Geological Survey, “Earthquake Statistics,” 2000–
2015, available at
https://earthquake.usgs.gov/earthquakes/browse/stats.php.
Accessed 7/21/2017.
Ground motion and energy comparison
• Magnitude is on a logarithmic scale
• When magnitude increases by 1, the ground motion
(amount of shaking) increases 10 times
- A M6 earthquake has 10 times larger ground motion than a M5
- A M6 has 100 times more than a M4
• Energy is different
- When magnitude increases by 1, amount of energy released
increases ~32 times

Relationship between physical fault
characteristics and Mw?
Magnitude versus Fault Length
10
100
1000
10000
6 7 8 9 10
Magnitude
F
a
u
lt
L
e
n
g
th

(
k
m
)
Magnitude of earthquake is controlled by fault length
(or area) that ruptures
Magnitude versus
fault length
(determined from
aftershock zone
length) for various
earthquakes (Alaska,
1964; Denali, 2002;
Landers, 1992; Loma
Prieta, 1989;
Northridge, 1994,
etc.). Results were obtained
using Seismic/Eruption views.
Alaska, 1964

Denali, 2002
Landers, 1992
Sumatra, 2004
Magnitude versus fault length
Northridge, 1994
Loma Prieta, 1989
Equivalent Mw of a
variety of seismic
events, human-
made events, and
other phenomena
Earthquake Intensity
• Measured by Modified Mercalli Scale
• Qualitative scale (I-XII) based on damage to structures and
people’s perceptions
• Can vary within an earthquake with a single magnitude
• Can vary from country to country

• Modified Mercalli Intensity Maps
• show where the damage is most severe
• Based on questionnaires sent to residents, newspaper articles,
and
reports from assessment teams
• Recently, USGS has used the internet to help gather data more
quickly
Abbreviated Modified Mercalli Intensity Scale
Maps of Intensity
Shake Maps use high-quality seismograph data to show areas of
intense shaking
Useful in crucial minutes after an earthquake
- Show emergency personnel where greatest damage likely
occurred
- Locate areas of possible damaged gas lines and other utilities
1994 M6.7 Northridge earthquake 2001 M6.8 Nisqually
earthquake
1994 Northridge
2001 Nisqually
Magnitude

is a measure for the size or energy release
of an earthquake
Intensity
is a measure for the degree of shaking
Factors Affecting Intensity
An earthquake has only one magnitude.
The same magnitude earthquake can
have different effects in different areas.
Why??
Intensity at a given location depends on:
- Earthquake magnitude
- Epicenter location
- Distance from epicenter
- Hypocenter depth
- Direction of rupture
- Duration of shaking
- Local soil conditions

- Building style
Depth of Focus
• Focus is the place
within the Earth where
the earthquake starts
• Depth of earthquake
influences the amount
of shaking
• Deeper earthquakes
cause less shaking at the
surface
• Lose much of the energy
before reaching surface
• Loss of energy is called
attenuation
Direction of Rupture
• Direction that the
rupture moves along
the fault influences the
shaking
• Path of greatest

rupture can intensify
shaking
• Directivity contributes
to amplification of
seismic waves
Direction of
Rupture
toward the
Area of Most
Intense
Shaking
Local Geologic Conditions
• Nature of the ground materials affects the earthquake
energy
• Different materials respond differently to an earthquake
• Depends on their degree of consolidation
- Seismic waves move faster through consolidated bedrock

- Move slower through unconsolidated sediment
- Move slowest through unconsolidated materials with high
water
content
• Material amplification
- Energy is transferred to the vertical motion of the surface
waves
Material
Amplification
of Shaking
Material
Amplification of
Shaking
El Salvador, 2001L’Aquila, 2009
Pakistan, 2005 China, 2008
Ground Motion During Earthquakes

• Buildings are designed to handle vertical forces (weight
of building and contents)
>>> vertical shaking in earthquakes is usually safe
• Horizontal shaking during earthquakes
>>> can do massive damage to buildings
• Acceleration
– Measured as acceleration due to gravity (g)
– Weak buildings can be damaged by as little as 0.1g
– At isolated locations, peak ground acceleration can be
as much as 1.8g (Tarzana Hills in 1994 Northridge, CA)
Periods of Buildings and Responses of Foundations:
• Buildings have natural frequencies and periods
• Periods of swaying are about 0.1 second per story
– 1-story house shakes at about 0.1 second per cycle
– 30-story building sways at about 3 seconds per cycle
• Building materials affect building periods
– Flexible materials (wood, steel) → longer period of shaking

– Stiff materials (brick, concrete) → shorter period of shaking
• Velocity of seismic wave depends on material through
which it is moving
– Faster through hard rocks/materials
– Slower through soft rocks/materials
Ground Motion During Earthquakes
Geographic Regions at Risk from Earthquakes
• Earthquakes not randomly distributed
• Most along plate boundaries
Geographic Regions at Risk from Earthquakes
• Earthquakes not randomly distributed
• Most along plate boundaries
Plate tectonics and earthquakes
Exists relation between tectonic environment, deformation
forces and earthquake characteristics

Divergent Zone
• Dominant
deformation force:
tension
• Stress is released
in frequent, strong,
and shallow
earthquakes
• E.g., East Pacific
Rise (MOR), East
African Rift System
(no oceanic litho
yet!)
Tension
Plate Boundary Earthquakes
• Subduction Zones
- Site of the largest earthquakes
- Megathrust earthquakes
- Example: Cascade Mountains
- Convergence between a continental and oceanic plate
- Example: Aleutian Islands

- Convergence between two oceanic plates
• Transform Fault Boundaries
- Example: San Andreas Fault in California, Loma Prieta
earthquake
- Boundary between North American and Pacific plates
Earthquakes at Convergent Zones
Convergent Zones
• Region where two tectonic plates collide
• Dominant deformation force – compression
- Infrequent and great earthquakes
- Immense amount of energy is stored, then suddenly released
- Shallow, intermediate and deep earthquakes
Megathrust
earthquakes due to
shear stress at the
contact between the

overriding and
subducting plates
2010 Chile Megathrust Earthquake
1960 M9.5 Chile
Earthquake –
largest known
Earthquake
1957
1964
1960
Magnitude 9+
2011
1700
All the M9.0 earthquakes are
along subduction zones!

All have generated tsunamis
Rupture surfaces for the Pacific Rim subduction zones
Potential areas for
M9.0 earthquakes.
Subduction zones
generate the really
large earthquakes.
Earthquakes in continent-
continent collisions
Active Faults in Tibet, China, Southeast Asia
What is the cause of all these faults?
Earthquakes along Transform Faults
• Dominant deformation force: shear
• Stress released in infrequent, major and shallow

earthquakes
• San Andreas fault, CA
- Transform fault accommodating horizontal movement
between the Pacific and North American plates
- NO material created nor consumed
- Fault created as a result of the subduction of the
Farallon plate under the North American plate in the last
30 Ma
20 Ma 10 Ma
Earthquakes along Transform Faults
Earthquakes and
hot spots
• Dominant deformation
forces: tension
(mainly) and shallow

earthquakes
• Frequent, strong and
shallow earthquakes
Earthquakes occur at shallow
depth due to magma movement
beneath the volcano
Hot spots and earthquakes
Hypocenters beneath
Kilauea volcano, Hawaii
When magma is on the
move at shallow depths,
it can generate a nearly
continuous swarm of
relatively small near-
surface earthquakes
Intraplate Earthquakes

• Earthquakes that occur within plates
• Example: New Madrid seismic zone
• Located near St. Louis, MO
• Historic earthquakes similar in magnitude
to West Coast quakes
• Often smaller M than plate boundary
quakes, but
• Can cause considerable damage due to
lack of preparedness
• Can travel greater distances through
stronger continental rocks
Plate Boundary vs. Intraplate Earthquakes
Why the difference in shaking areas?
Intraplate Earthquakes of Eastern Canada
Ancient St.
Lawrence River Rift

and its two failed
arms
Earthquake Effects
• Primary – caused directly by fault movement
• Ground shaking
• Surface rupture
• Secondary
• Liquefaction of ground
• Regional changes in land elevation
• Landslides
• Fire
• Tsunamis
• Disease
Shaking and Ground Rupture
• Ground rupture
- Displacement along the fault causes cracks in surface

• Fault scarp
• Shaking
- Causes damage to buildings, bridges, dams, tunnels,
pipelines, etc.
- Measured as ground acceleration
- Buildings may be damaged due to resonance
• Matching of vibrational frequencies between ground and
building
Site Amplification
Liquefaction
• A near-surface layer of water-saturated sand changes
rapidly from a solid to a liquid
• Causes buildings to “float” in earth
• Common in M 5.5 earthquakes in younger sediments
• After shaking stops, ground re-compacts and becomes
solid
Liquefaction, cont.

Regional Changes in Land Elevation
• Vertical deformation linked to some large earthquakes
• Regional uplift
• Subsidence
• Can cause substantial damage on coasts and along streams
• Can raise or lower
the ground-water table
http://www.nzgs.org/library/uc-geologists-key-
contributors-to-fault-rupture-mapping-following-
the-m7-8-kaikoura-earthquake/
http://www.nzgs.org/library/uc-geologists-key-contributors-to-
fault-rupture-mapping-following-the-m7-8-kaikoura-earthquake/
Landslides
• Most closely linked natural
hazard with earthquakes
• Earthquakes are the most
common triggers in
mountainous areas

• Can cause a great loss of
human life
• Can also block rivers creating
“earthquake lakes”
2002 Nov 3: Denali M 7.9 earthquake
Caused landslides in mountains (unpopulated areas)
Mosaic view of rock avalanches across Black Rapids Glacier.
Photo by Dennis Trabant, USGS; mosaic by Rod March, USGS
2002 Nov 3: Denali Mw7.9 earthquake
2002 Nov 3: Denali Mw7.9 earthquake
Fires
• Shaking and surface displacements
• Cause power and gas lines to break and ignite
• Knock over appliances, such as gas water heaters, and leaks
ignite
• Threat even greater due to

• Damaged firefighting equipment
• Blocked streets and bridges
• Broken essential water mains
Tsunamis
• Long wavelength sea waves (160km)
• 800 km/hr (500 mi/hr)
• Long wave periods [160km/(800km/hr)] =12 min.
• Generated by
- Earthquake displacement of seafloor
- Submarine mass slides
- Explosive volcanic eruptions
- Impacts
2004 Sumatra Earthquake
and Tsunami
Disease

• Causes:
- Loss of sanitation and housing
- Contaminated water supplies
- Disruption of public health services
- Disturbance of the natural environment
- Rupture of sewer and water lines
• Water polluted
Groundwater and Energy Resources
• Geologic faults from earthquakes greatly influence
underground flow of:
- Water
- Oil
- Natural gas
• Fault zones can act as preferential paths
• Can create natural and underground dams
- Slow or redirect flow
- Oases in some arid areas
- Accumulation of oil and gas
Mineral Resources

• Faulting may be responsible for accumulation or
exposure of economically valuable minerals
• Mineral deposits develop along fault cracks called
veins
- Can be the source of precious metals
- Those on large fault zones may produce enough to be
economically viable for extraction
Earthquakes Caused by Human Activity
• Loading Earth’s crust, as in building a dam and
reservoir
- The weight from water reservoirs may create new faults or
lubricate old ones
• Injecting liquid waste deep into the ground through
disposal wells
- Liquid waste disposals deep in the earth can create pressure
on faults
• Creating underground nuclear explosions
- Nuclear explosions can cause the release of stress along
existing faults

Induced Seismicity?
• Earthquake activity
that occurs above the
rate of naturally
occurring seismicity
due to human activity
• Injection of large
volumes of water at
high pressures ➔
hydraulic fracking
Future Earthquake Hazard Reduction
• Frequent small earthquakes
- May help prevent larger ones
- Release pent-up energy
- Reduction of elastic strain
• Scientists try to identify areas that have not

experienced earthquakes in a long time
- Greatest potential for producing large earthquakes
Minimizing the Earthquake Hazard
• Earthquakes strike without warning
- Great deal of research devoted to anticipating earthquakes
- Focus of minimization is on forecasting and warning
• Forecasts assist planners
- Considering seismic safety measures
- People deciding where to live
• Long-term forecasts
- Do not help anticipate and prepare for a specific earthquake
- Need predictions, but not there yet
The National Earthquake Hazard
Reduction Program
• Major goals
- Develop an understanding of the earthquake source

• Obtaining information about the physical properties and
mechanical
behavior of faults
• Develop models of the physics of the earthquake process
- Determine earthquake potential
• Detailed study of active regions, determine rates of
deformation
• Calculate probabilistic forecasts
- Predict effects of earthquakes
• Obtain information to predict ground rupture and shaking and
effects on
structures
• Apply research results
The Canadian National Seismograph Network
Seismic Risk
RISK = VULNERABILITY x HAZARD
Where is vulnerability especially high?
How to determine seismic hazard?

1. Where in the past have we felt significant earthquakes?
2. Are there any geographic patterns? Magnitude repeats?
3. Which areas are most vulnerable?
Seismic Risk
RISK = VULNERABILITY x HAZARD
Where is vulnerability especially high?
How to determine seismic hazard?
What
patterns
do you
see?
Seismic Risk
National Building Code of Canada (NBCC)
Seismic guidelines used to design and construct buildings that
are as

earthquake-resistant as necessary for the expected seismic
hazard of their
setting
Classification based on velocity of shear waves in the top 30 m
of material
Estimation of
Seismic Risk
• Hazard maps show
earthquake risk
• Probability of a
particular event or the
amount of shaking
• Damage potential
determined by how
the ground moves and
how the buildings
within the affected
region are constructed
http://earthquakescanada.nrcan.gc.ca/hazard-alea/simphaz-
en.php
Estimation
of Seismic

Risk in
California
Earthquake Prediction
• The when and where of
a future earthquake
• Not currently possible
with our knowledge of
faults and stress
• Would require:
• The current stress stage of
a fault
• The maximum strength of
a fault
• The stress stage after an
earthquake
Earthquake Forecasting
• The likelihood of

earthquakes happening in
a specified area over a
specified period
• Can be determined from:
• Known faults
• Historical earthquakes
• Seismicity maps
• Paleoseismology from
trenches
• Geodetic strain rates from
GPS - crustal motion maps
Short-Term Prediction
• Pattern and frequency of earthquakes
- Foreshocks
• Deformation of ground surface
- Changes in land elevation
• Seismic gaps along faults

- Areas that have not seen recent quakes
• Geophysical and Geochemical changes
- Changes in Earth’s magnetic field, groundwater levels
Earthquake Warning Systems?
• Possible? Technically yes…
could develop system that
would provide up to 1
minute of warning
• Network of seismometers and
transmitters along the San
Andreas Fault
• Earthquake warning system
NOT a prediction tool –
earthquake has already
happened
• Concern for liability issues
• False alarms
• Failures

Community Adjustments to the Earthquake Hazard
• Location of critical facilities
- Should be located in earthquake safe locations
- Need detailed maps of ground response (microzonation)
• Structural protection
- Buildings must be designed and/or retrofitted to withstand
vibrations
- “Earthquakes don’t kill people, buildings kill people”
• Education
- Could include pamphlets, workshops, information on internet
- Earthquake and tsunami drills
• Increased insurance and relief measures
- Vital to help recovery from an earthquake
Earthquake Hazard Model Design
Earthquake
Hazard
Model

Design
example
2011 Tohoku Earthquake
• M 7.2 earthquake detected two days before
- This was a size that was predicted to happen any day
- Did not expect it to be a foreshock to a larger earthquake
• Pacific plate slid under the Eurasian plate
- Earthquake 500 times more powerful than history suggested
- Also produced larger than predicted tsunami
• Automatic alert went out 8 seconds after P waves
confirmed
- Allowed 10 seconds of preparation
2011 Tohoku
Earthquake, cont.
• Few buildings
collapsed
• Allowed occupants to
escape
• However, widespread

superficial damage and
minor structural damage
• Most damage due to
tsunami damage,
liquefaction, and
landslides
• M 9.0 earthquake
triggered a tsunami that
was up to 120 m
• Fukushima nuclear
disaster
Japan
The most seismically active
country in the world. 2 or 3 large
earthquakes per century
Up to 5 M8 earthquakes per
century!
http://www.esri.com
http://prezi.com
Mexico City, 1985
• Mw 8.3 megathrust earthquake broke ~350 km away from

Mexico City
• ~10,000 people died
• What caused this
earthquake?
• Michoacan
Seismic gap
North
American
plate
Cocos plate
Why so much shaking
here??
Observations - Mexico City, 1985
• Very strong motions produced 400 km from the fault rupture
due to the
response of soft clays (i.e. near-surface geology)

• Motion and damage should have been minimal because of
distance
from source
Resonance!
• Amplification of
surface waves
due to sediment
filled basin
• Specific
resonance of
medium-height
buildings
• Weak structures
Most severe damage to almost
400 buildings of between 7 and
18 storeys in height. (EEFIT,

1986)
Chapter 3 Summary
• Earthquakes are common along tectonic plate boundaries
where faulting is common.
• Faults are fractures where rocks on one side of the
fracture have been offset with respect to rocks on the
other side.
• Displacement is caused by compressional, tensional, or
shearing stresses and can be mainly horizontal or mainly
vertical.
Chapter 3 Summary, cont.
• A fault is usually considered active if it has moved during
the past 10,000 years and potentially active if it has moved
during the past 2 million years.
• Before an earthquake, elastic strain builds up in the rocks
on either side of a fault as the sides pull in different

directions.
• Released elastic strain energy radiates outward in all
directions from the ruptured surface of the fault in the form
of seismic waves.
• Seismic waves are vibrations that compress (P) or shear
(S) the body of Earth or travel across the ground as
surface waves.
• Some faults exhibit tectonic creep, a slow displacement
not accompanied by felt earthquakes.
• Large earthquakes release a tremendous amount of
energy measured on a magnitude (M) scale.
• Earthquake intensity varies with the severity of shaking
and is affected by proximity to the epicenter, the local
geological environment, and the engineering of structures.

• Buildings highly subject to damage are those that (1) are
constructed on unconsolidated sediment, artificially filled
land, or water-saturated sediment, all of which tend to
amplify shaking; (2) are not designed to withstand
significant horizontal acceleration of the ground; or (3)
have natural vibrational frequencies that match the
frequencies of the seismic waves.
• Most earthquakes occur on faults near tectonic plate
boundaries.
• Intraplate earthquakes are also common various parts of
the United States.
• Some of the largest historic earthquakes in North America
occurred within the plate in the central Mississippi Valley in
the early 1800s.

• The primary effect of an earthquake is violent ground
motion accompanied by fracturing, which may shear or
collapse large buildings, bridges, dams, tunnels, pipelines,
levees, and other structures.
• Other effects include liquefaction, regional subsidence,
uplift of the land, landslides, fires, tsunamis, and disease.
• Natural service functions include enhancing groundwater
and energy resources and exposing or contributing to
formation of valuable mineral deposits.
• Human activity has locally increased earthquake activity
by fracturing rock and increasing water pressure
underground below large reservoirs, by deep-well disposal
of liquid waste, and by setting of underground nuclear
explosions.
• Understanding how we have caused earthquakes may
eventually help us control or stop large natural

earthquakes.
• Reducing earthquake hazards requires detailed mapping
of geologic faults, the cutting of trenches to determine
earthquake frequency, and detailed mapping and analysis
of earth materials sensitive to shaking.
• Adjustments to earthquake hazards include improving
structural design to better withstand shaking, retrofitting
existing structures, microzonation of areas of seismic risk,
and updating and enforcing building codes.
• To date, scientists have been able to make long- and
intermediate-term forecasts for earthquakes using
probabilistic methods but not consistent, accurate short-
term predictions.
• Early warning systems have been shown to be effective in

Japan, but no such system exists in the United States or
Canada.
• Warning systems and earthquakes prevention are not yet
reliable alternatives to earthquake preparedness.
CH. 4 - TSUNAMIS
Energy and Natural Hazards
No subduction zones!
No faults that could
create even a large
tsunami, let alone a
“megatsunami”
Learning Objectives

• Explain the process of tsunami formation and development.
• Locate on a map the geographic regions that are risk tsunamis.
• Synthesize the effects of tsunamis and the hazards they pose
to coastal regions.
• Summarize the linkages between tsunamis and other natural
hazards.
• Tsunamis are not caused by or affected by human activities,
but damages are compounded as coastal populations increase.
• Discuss what nations, communities, and individuals can do to
minimize the tsunami hazard.
Introduction to Tsunamis
• Tsunami is Japanese for “harbour wave”
• Caused by a sudden vertical displacement of ocean water
• Triggered by:
• Large earthquakes that cause uplift or subsidence of sea floor
• Underwater landslides
• Volcano Flank Collapse
• Submarine volcanic explosion
• Asteroids
• Can produce Mega-tsunami

• “Tidal Wave” – misnomer!
• Tsunamis are not related to tides
Some Historic Tsunamis
General Wave Attributes
Properties of Seismic Waves:
• Amplitude: height of wave
• Wavelength: distance between successive wave peaks
• Period [s]: time between wave peaks (= 1/frequency)
• Frequency [Hz]: number of wave peaks in one second
Tsunami Waves
• Series of waves with long wavelengths (20 km to over 800
km)
and long periods (10 minutes to 1 hour)
• The restoring force is gravity (compare with seismic waves:
elastic waves where restoring force is springiness of rocks)
• Velocity depends on water depth:

g is gravitational acceleration (9.8 m/s2)
d is water depth
v = gd
Tsunami vs. Wind-caused waves
• Wind-caused waves
- water rotates in circles
- short wavelength
- short period
• Tsunami
- flow as massive sheets of
water
- long period
- long wavelength (the
longer the wavelength, the
slower the wave loses
kinetic energy)

How do Earthquakes Cause a Tsunami :
Point source
• Volcano- and landslide-caused tsunami
• Trigger is a point source
- Energy flows away radially, high attenuation, local damage
Tsunami waves
propagate radially
when it is a point
source
How do Earthquakes Cause a Tsunami –
Fault Source
Linear source:
fault (on seafloor)
that ruptures
Tsunami waves
propagate mainly in
direction
perpendicular to fault

Low attenuation:
potential for damage
far from source
How do Earthquakes Cause a Tsunami?
• Two mechanisms:
- Seafloor movement (more common)
- Triggering a landslide
• Takes an earthquake of M 7.5 or greater
- Creates enough displacement of the seafloor
- Upward or downward movement displaces the entire mass of
water
- Starts a four-stage process
How do Earthquakes cause a Tsunami?
1. Earthquake uplifts or downshifts the seafloor
• Rupture uplifts the seafloor
• A dome forms on the surface of the water above the fault

• Dome collapses and generates the tsunami wave
• Waves radiate outward (like a pebble in a pond)
2. Tsunami moves rapidly in deep ocean
• Can travel 720 km per hour
• Spacing (frequency) of crests is large and small amplitude
• Boats in open ocean don’t notice the tsunami waves
Characteristics of Ocean Waves
• Characteristics common to all waves propagating in the
open ocean:
- Water moves in forward-rotating circles
- Diameter of circles decreases with depth
- Negligible for depth > L/2
In open ocean:
H < 1m
Shoaling
• Occurs when waves interact with the seafloor near

the shoreline
• Interaction starts when depth < L/2
• Friction slows wave down
• Wavelength decreases
- Energy is concentrated in a shorter length
• Amplitude increases
- Wave breaks
Near shore:
H ~ 6-15 m
Characteristics of Ocean Waves
Longer
wavelength in
deep water
Shorter
wavelength in
shallow water

3. Tsunami nears land, loses speed, gains height
- Depth of ocean decreases, slowing tsunami waves
45 km per hour
- More water piles up increasing amplitudes and frequency
4. Tsunami moves inland destroying everything in its path
- Can be meters to tens of meters high
- Often arrives as a quick increase in sea level
- Trough may arrive first, exposing seafloor
- Runup, furthest horizontal and vertical distance of the largest
wave
- Water returns to ocean in a strong, turbulent flow
- Edge waves may be generated parallel to the shore
- Second and third waves may be amplified
• Offshore earthquakes can
cause tsunamis to go
toward land and out to sea
• Uplifted dome of water splits in

two waves
• Distant tsunami
• Travels out to sea and travels
long distances with little loss of
energy
• Local tsunami
• Travels quickly towards land
• People have little time to react
How do landslides cause a tsunami?
• Submarine landslides occur
when landslides occur
underneath the water
- Displaces water vertically causing
tsunamis
• On land, rock avalanches from
mountains can cause tsunami
- Example: Lituya Bay, Alaska
- 30.5 million cubic meters of rock
fell into ocean

- Bay water surged to 524 m (1790
ft.) above normal
Geographic Regions at Risk from Tsunamis
• All oceans and some lake shorelines have some risk
- Greater risk is for coasts near sources of tsunamis
- Which are??
• Greatest risk is to areas near or across from
subduction zones
- Example: Cascadia zone, Chilean Trench, off Coast of Japan
Where do the most tsunamis occur?
a) Indian and Atlantic oceans
b) Atlantic and Pacific oceans
c) Pacific and Indian oceans
d) Indian and Arctic oceans
e) Arctic and Atlantic oceans

Ring of Fire = Subduction zones
Where do the most tsunamis occur?
a) Indian and Atlantic
oceans
b) Atlantic and Pacific
oceans
c) Pacific and Indian
oceans
d) Indian and Arctic
oceans
e) Arctic and Atlantic
oceans
Why is the tsunami hazard in the Atlantic so low?

Tsunamis arrive as the leading edge of an elevated mass of
water
- Similar to a very rapidly rising tide
- NOT breaker shape
Runs up and over the beach, floods inland for many minutes
Near shore topography (bays,
inlets) can focus the energy and
locally create enormous waves
Why does water often recede ahead of
a tsunami wave?
Water recedes
Direction of
propagation of
tsunami wave
e
q
u
il
ib

ri
u
m
Trough hits
shore first
Why does water often recede ahead of
a tsunami wave?
Water runs up
Direction of
propagation of
tsunami wave
e
q
u
il
ib
ri
u
m
Peak follows a
few minutes later

1960 Chile M 9.5 earthquake
• Most powerful earthquake ever measured
Earthquake-generated tsunami: 1960 Valdiva M 9.5
Case Study : Sumatra
• 26 December, 2004
• M9.2 megathrust earthquake
• 3-4 min. of ground shaking,
250 km offshore
• Death and destruction in 13
countries:
- 198,000 deaths Indonesia
- 30,000 deaths Sri Lanka
- 11,000 deaths India
- 6000 deaths Thailand
• 1200 km long fault
• Seafloor offsets of up ~10 m
• Travelled 1.5 km inland

Case Study – Sumatra
• Megathrust event
- Most lethal tsunami in recorded
history
- No warning system in Indian Ocean
- Few people knew what tsunami
meant prior to event
• Education (or lack of) was a
major reason for so many
deaths
- Many did not know how to
recognize a tsunami
- Many went to beach to watch
- Few knew what to do
- Tourists and first-generation residents
2004 Sumatra Tsunami killed people
on both sides of Indian Ocean

2004 Sumatra Earthquake
2004 Sumatra Earthquake, cont.
• Those that were educated
• Scientists on beach in Sri Lanka
• Noticed the sea level drop
• Sounded warning for those that went to beach to watch
• Animal behavior
• Elephants started trumpeting about time of earthquake
• Ignored handlers and headed up hill
• Education of tsunami could have saved thousands more,
especially
with the distant tsunamis
June 23, 2004 December 28, 2004
Effects of Tsunamis and Linkages with Other
Natural Hazards
• Primary effects
- Inundation of water and resulting flooding and erosion
- Shorten the coastline
- Debris erodes both landscape and human structures

• Secondary effects
- Fires
- From ruptured gas lines or other sources
- Contaminated water supplies
- Floodwaters, wastewater treatment plants, rotting animal
carcasses and
plants
- Disease
- Come in contact with polluted water or soil
• Coastline erosion
CH. 2 – INTERNAL STRUCTURE OF THE EARTH
AND PLATE TECTONICS
Learning Objectives
• Describe the basic internal structure and processes of Earth.
• Summarize the various lines of evidence that support the
theory of
plate tectonics.

• Compare and contrast the different types of plate boundaries.
• Explain the mechanisms of plate tectonics.
• Outline how plate tectonics has changed the appearance of
Earth’s
surface over time.
• Compare and contrast the two fundamental processes that
drive plate
tectonics.
• Link plate tectonics processes to natural hazards.
Learning Objectives
theory of
plate tectonics.
Earth’s
surface over time.
drive plate
tectonics.

Lithospheric Plates of the World
Earth and its Interior
Two Cities on a Plate Boundary
• California straddles the
boundary between two
tectonic plates
• San Andreas fault: boundary
between North American and
Pacific plates
• Los Angeles and San Francisco
located on opposite sides of the
fault
• Movement of San Andreas
fault in 1906
• Caused major earthquake
• Earthquakes not understood at
the time
• Scientific investigations led to
identification of fault and new
understanding of earthquakes

Plate Tectonics – Shift happens!
• Large-scale geologic processes that deform Earth’s
lithosphere
• Produce
landforms such
as ocean
basins,
continents, and
mountains.
• Processes are
driven by forces
within Earth
Movement of the Tectonic Plates
• Lithosphere is broken into pieces
• Lithospheric plates or tectonic plates
• Plate tectonics

• Plates move relative to one another
• Plates are created and destroyed
• Boundaries between lithospheric plates are geologically
active areas
• Responsible for several of the most devastating natural
hazards, such as earthquakes and volcanoes
Earth’s Plates
THREE types of plate boundaries:
1. Divergent
2. Convergent
3. Transform
Earth’s Plates
Location of volcanoes and earthquakes is not random!
Fit of the Continents
• Antonio Snider-Pelligrini (1858),

a geographer cut out a map of
Africa and South America
suggesting they were connected
at one time
• Other physical evidence based
on observation (maps, fossils
etc.) was used by Wegener
Continental Drift Hypothesis
• Alfred Wegener proposed
the hypothesis of
continental drift in 1915
• Theory based on congruity
of the shape of the
continents and similarity of
fossils in South America +
Africa
• Theory not accepted
because could not explain
how continents moved
Alfred Wegener Institute

Movement of the Tectonic Plates, cont.
• Seafloor spreading
• Explained mechanism for plate tectonics
• At mid-ocean ridges new crust is added to edges of
lithospheric plates
• Continents are carried along plates
• Crust is destroyed along other plate edges
• Subduction zones
• Earth remains constant, never growing or shrinking
Model of Plate Tectonics
The tectonic cycle – the “conveyor belt” model
1
2
3
The lithosphere moves laterally as if it were a conveyor belt

Direction of motion
The lithosphere moves laterally as if it were a conveyor belt
Direction of motion
Convection loop
• Sinking plates generate volcanoes and earthquakes
• Sinking ocean plates are wet and cold
• Plates come in contact with hot asthenosphere
• Plates melt to generate magma
• Magma rises to produce volcanoes
• Volcanic arcs
• Earthquakes occur along the path of the descending plate
• Wadati-Benioff zones
• Plate collides with another plate
• Denser plate dives under the

less-dense plate and is recycled
Denser plate: subducting plate
Less-dense plate:
overriding plate
Subduction Zone
• Plate collides with another plate
• Denser plate dives under the
less-dense plate and is recycled
• Dark blue linear features = deep water
• Deep trenches
where plates
re-enter the
asthenosphere
• Surface
expression of
subduction

zones
• Light blue linear features = shallow water
• Along mid-
oceanic ridges
• Bulge caused
by
asthenosphere
flowing
upwards
• Surface
expression of
spreading
centers
• Plate tectonics is a unifying theory

• Explains a variety of phenomena
• Evolutionary change
• How Earth works
• Direction of plate movement
• Distribution of earthquakes and volcanoes
• Similarities among fossils on different continents
• Changes in Earth’s magnetism
• Convection likely drives plate tectonics
Plate Movement
Hypothetical convection cells that may drive plate tectonics
Plate Movement
Internal Earth mostly solid, NOT liquid! Mantle is a
visco-elastic material
Types of Plate Boundaries
Defined by the relative movement of the plates on either

side of the boundary
Types of Plate Boundaries, cont.
Divergent Boundaries
• Plates move apart during seafloor spreading
• Magma from asthenosphere rises
Plates are pulled apart
under tension at
divergent zones:
pressure on
superheated
asthenosphere rock

and heat causes
expansion and
elevation of
overlying
lithosphere
Gravity pulls the dome
downward:
down-dropped rift
valleys
es,
magma rises up through
cracks to build
volcanoes
continues, seafloor

spreading takes over,
down-dropped linear rift
valley fills with ocean
Divergent Boundaries around the World
Convergent Plate Boundaries: Subduction Zones
What pulls the
plate down?
Convergent Plate
Boundaries:
Collision Zones
Gros Morne National Park, Newfoundland
500 million years ago, a large piece of oceanic lithosphere
was scraped off the downgoing plate as it was subducting

Tabelands – access
to complete thickness
of the oceanic
lithosphere from the
upper mantle to the
Earth’s surface
3D view of different tectonic environments
Continent-Continent Collision
Credit: USGS
Continental collision between the
Indian and Asian plates
Tectonic
map
showing

India
pushing
into Asia
Transform Plate Boundaries
Plates slide past each other
Divergent Boundaries & Transform Faults
Rates of Plate Motion
• Plate motion is fast (geologically)
- Plates move a few centimeters per year
• Movement may not be smooth or steady
• What happens when the rough edges along the plate
move quickly?
• Plates can displace by several meters during a great
earthquake
- Such as with San Andreas fault
North American Plate Boundary

Subduction in California
Plate tectonics – Supporting evidence
• Oceanography
- Magnetization patterns on seafloor
- Age of ocean basins
- Bathymetry
• Earthquake hypocenters and epicenters
• Matching of fossils and rock types across
continents
A Detailed look at Seafloor Spreading
• Mid-ocean ridges discovered by Harry H. Hess
• Validity of seafloor spreading established by:
1) Identification and mapping of oceanic ridges
2) Dating of volcanic rocks on the floor of the ocean
3) Understanding and mapping of the paleomagnetic

history of ocean basins
https://www.e-
education.psu.edu/earth520/node/1811
Ocean bottom is on average about 3.8 km deep,
with two main exceptions:
• Continuous mountain ranges
-- several thousand feet in elevation from ocean floor
-- extend more than 65,000 km along ocean floors
– Volcanic mountains that form at spreading centers,
where plates pull apart and magma rises to fill gaps
• Narrow trenches extend to depths of more than 11 km
– Where tops of subducting plates turn downward
to enter mantle
Evidence of Plate Tectonics: Seafloor Topography
Ocean bottom is on average about 3.8 km deep,
with two main exceptions:
• Continuous mountain ranges
-- several thousand feet in elevation from ocean floor

-- extend more than 65,000 km along ocean floors
– Volcanic mountains that form at spreading centers,
where plates pull apart and magma rises to fill gaps
• Narrow trenches extend to depths of more than 11 km
– Where tops of subducting plates turn downward
to enter mantle
Evidence of Plate Tectonics: Seafloor Topography
Paleomagnetism
• Earth’s magnetic field can
be represented by a dipole
• Forces extend from North to
South Poles
• Magnetic poles do not
coincide exactly with
geographic poles
• Movements of iron-rich fluid
generate a magnetic field
around Earth
- Which layer of Earth is
responsible for this?

Paleomagnetism
• Earth’s internal magnetic
field NOT constant through
time
• Over a few years: magnetic
poles wander around the
geographic poles
• Polarity reversal ~ every
few 100,000 yrs
- North magnetic pole south
magnetic pole
Normal polarity
(eg. Today)
Paleomagnetism, cont.
• Magnetic field has permanently magnetized some surface
rocks at
the time of their formation
- Iron-bearing minerals orient themselves parallel to the
magnetic field at the critical temperature known as Curie
Point
- Thermoremnant magnetization
Paleomagnetism is the

study of magnetism of
rocks at the time their
magnetic signature is
formed
• Some volcanic rocks show
magnetism in opposite
direction as today
• Earth’s magnetic field has
reversed
• Cause is not well known
- Reversals are random
- Occur on average every few
hundred thousand years
• Magnetic stripes
- Geologists towed
magnetometers along ocean

floor to measure magnetic
properties of rocks
- When mapped, the ocean
floor had stripes
• Areas of “regular” and “irregular”
magnetic fields
• Stripes were parallel to oceanic
ridges
• Sequences of stripe width
patterns matched the
sequences established by
geologists on land
Magnetic Anomalies on the Seafloor
• Using the magnetic anomalies, geologists can infer
ages for the ocean rocks
- Seafloor is no older than 200 million years old
• Spreading at the mid-ocean ridges can explain stripe

patterns
- Rising magma at ridges is extruded
oCooling rocks are normally magnetized
oField is reversed with new rocks that push old rocks away
Magnetic Reversals and Seafloor Spreading
Notice symmetry on either side of the ridge!
Magnetism and Age of the Seafloor
Map of magnetically striped Pacific
Ocean floor off Vancouver Island:
- Black areas are normally
magnetized
- Yellow areas point to reverse
polarity
Systematic increases in seafloor depth

• Ocean floor depths increase systematically with seafloor
age, moving away from mid-ocean ridges
• Why? As oceanic crust gets older, it cools and becomes
denser, therefore sinking lower into mantle.
Seafloor Topography and Age
Age of the Ocean Floor
The present ocean floors are no older than
200 million years, WHY??
Age of the Ocean Floor, cont.
• Subduction!
• Thick, buoyant, continental crust stable at Earth’s surface
• Continents form by:
• Accretion of sediments
• Addition of volcanic materials
• Collisions of tectonic plates carrying continental landmasses
• Pattern of magnetic stripes allows us to reconstruct how

plates and continents embedded in them have moved
throughout history
• Hot spots
• Volcanic centers resulting from hot materials from deep in
the mantle
• Materials move up through mantle and overlying plates
• Found under both continental and oceanic crust
• Continental: Yellowstone National Park
• Oceanic: Hawaiian-Emperor Chain
• Plates move over hot spots creating a chain of island
volcanoes
• Seamounts are submarine volcanoes
Hawaiian Hot
Spot

Pangaea and Present Continents
• Movement of plates is responsible for present shapes
and locations of continents
• 180 million years ago there was the break-up of Pangaea
• Supercontinent extending from pole to pole and halfway
around Earth
• 50 Million years ago India crashed into China creating the
Himalayas
• Reconstruction of Pangaea and recent continental
drift clears up:
• Fossil data difficult to explain with separated continents
• Evidence of glaciation on several continents
Two
Hundred
Million
Years of
Plate
Tectonics
180 million years ago

Two
Hundred
Million
Years of
Plate
Tectonics
Paleontological Evidence for Pangaea
Ancient Mountain Ranges
The same sequence of rocks is found in
North America, Great Britain, and Norway.
The pattern does not make sense with the
continents in their current configuration.
Matching rock types and rock ages

Glacial
Evidence for
Pangaea
• Glaciers carve the rock as they
move.
• Scientists can determine the
direction of movement
Reconstructed ice sheet on
Gondwana.
How Plate Tectonics works: Putting it Together
• Two possible driving mechanisms for plate tectonics
• Ridge Push and slab pull
• Ridge push is a gravitational push away from crest of
mid-ocean ridges
• Slab pull occurs when cool, dense ocean plates sink
into the hotter, less dense asthenosphere
• Weight of the plate pulls the plate along
• Evidence suggests that slab pull is the more
important process

Push and Pull in Moving Plates
Plate Tectonics and Hazards
• Divergent plate boundaries (Mid-Atlantic Ridge) exhibit
earthquakes and volcanic eruptions
• Transform boundaries (San Andreas Fault) have great
earthquake hazards
• Convergent subduction plate boundaries are home to
explosive volcanoes and earthquake hazards
• Convergent collision plate boundaries have high
topography (Tibetan Plateau) and earthquakes
• Internal structure of Earth can be divided into layers
or concentric shells, based on either composition or
physical properties.
• The uppermost physical layer of Earth is known as
the lithosphere and is relatively strong and rigid
compared with the soft asthenopshere underlying it.
• A convection cell is a temperature-driven circulation

pattern that is assumed to operate within Earth and
may be involved in driving plate tectonics.
Chapter 2 Summary
• The lithosphere is broken into large pieces called
tectonic plates that move relative to one another.
• The three types of plate boundaries are divergent,
convergent, and transform faults.
• Evidence supporting plate tectonics theory includes
seafloor spreading, continental drift, the configuration
of hot spots and chains of volcanoes, and Wadati-
Benioff zones.
• Convection currents in Earth’s liquid outer core
generates a magnetic field that is sufficiently strong
to be recorded in rocks that contain magnetic
minerals.

• The seafloor spreading hypothesis proposed a
mechanism for continental drift.
• Seafloor spreading is confirmed using the
paleomagnetic signature of the seafloor centered
around the mid-ocean ridges.
• The age of the seafloor is younger than 200 million
years old, which is 20 times younger than the age of
continents.
• Hot spots are plumes of hot rock that rise from deep
in the mantle and cause volcanoes above them at
Earth’s surface.
• Alfred Wegener’s continental drift hypothesis
suggested that all of Earth’s continents were in the
past assembled in a single enormous continent,
known as Pangaea.
• With the validation of the seafloor spreading,
continental drift was confirmed and several long-

standing geologic problems have been resolved.
• The driving forces in plate tectonics are ridge push
and slab pull.
• Plate tectonics is extremely important is determining
the occurrence and frequency of volcanic eruptions,
earthquakes, and other natural hazards.
• Divergent plate boundaries are linked to earthquakes
and volcanic eruptions, but the risk is low because most
do not occur on land.
• Transform boundaries are linked to earthquakes and
represent and appreciable risk as these faults occur on
land and stretch for long distances, often through
populated regions.
• Convergent plate boundaries are zones of greatest risk
as these are linked to the largest recorded earthquakes,
explosive volcanic eruptions, and tsunamis.

CH. 3 - EARTHQUAKES
https://www.usgs.gov/news/updat
e-magnitude-71-earthquake-
southern-california
https://www.usgs.gov/news/update-magnitude-71-earthquake-
southern-california
Earthquake
Alert!
M6.4 and M7.1
earthquakes occurred
in Southern California
within 36 hours of
each other, 11 km
apart

Learning Objectives
• Compare and contrast the different types of faulting.
• Explain the formation of seismic waves.
• Summarize the processes that lead to an earthquake and the
release of
seismic waves.
• Differentiate between the magnitude scales used to measure
earthquakes.
• Identify global regions at most risk for earthquakes, and
describe the
effects of earthquakes.
• Describe how earthquakes are linked to other natural hazards.
• Explain how human beings interact with and affect earthquake
hazards.
• Propose ways to minimize seismic risk and suggest
adjustments we can
make to protect ourselves.
Energy and Natural Hazards
2011 Tohoku Earthquake
• Japan located just 200 km (~124 mi) west of Japan

Trench
• Pacific plate is subducting beneath Eurasian plate (9 cm/yr)
• Experiences frequent large earthquakes
• March 11, 2011
• Strongest recorded earthquake to hit Japan
• Significantly greater than considered possible
• Released about 600 million times more energy than bomb on
Hiroshima
• Well engineered buildings helped reduce the loss of lives due
to
structural collapse
• Greatest loss of life was due to tsunami
Shaking and Damage During the Tohoku Earthquake
Introduction to Earthquakes
• What is an earthquake?
• The sudden slip on a fault (release of elastic energy), and the
resulting ground shaking and radiated seismic energy caused by
the
slip {USGS, 2002}
• People feel approximately 1 million earthquakes a year
• Few are noticed very far from the source

• Even fewer are major earthquakes
• Most earthquakes occur along plate boundaries
Earthquake Distribution
Faults and Faulting
• Earthquakes occur along faults
• Plane of weakness in Earth’s crust
• Semi-planar fracture or fracture system where rocks are
broken
and displaced
• Fracture (crack) in the earth, where the two sides of the earth
move
past each other
• Centuries-old mining terminology used
• Footwall
• Hanging wall

Basic Fault
Features
Footwall
Hanging wall
Faults and Faulting, cont.
• Faulting – process of fault rupture
• Similar to sliding one rough board past another
• Slow motion due to friction
• Stresses the rocks along the fault
• Rocks rupture and displaced when stress exceeds strength of
rocks
• Stress
• Force that results from plate tectonic movements
• Tensional
• Compressional

• Shearing
• Strain
• Change in shape or location of the rocks due to the stress
Faults ≠ Plate boundaries
• However, most faults occur along plate boundaries
• Fault types
- Distinguished by direction of rock displacement
• Three basic types:
1. Dip-slip
a) Normal
b) Reverse
2. Strike-slip
a) right-lateral
b) left-lateral
3. Oblique slip
Normal dip-slip
• Vertical motion

• Hanging wall moves down
relative to footwall
Reverse dip-slip
• Vertical motion
• Hanging wall moves up relative
to footwall
Strike-slip • Crust moves in horizontal direction
Faults and Faulting, cont.
• Blind faults do not extend to the surface
Types of Plate Boundaries and Stress
• Divergent = Extensional Stress >> Normal Faulting
• Convergent = Compressional Stress >> Thrust
or Reverse Faulting

• Transform = Shear Stress >> Strike-Slip Faulting
Block diagram of fault surface
Faults are not simple planar
surfaces!
Faults are complex zones of
breakage where rough and
interlocking rock is held
together over an irregular
surface.
Stress builds up over many
years before enough energy
is stored to allow rupture on
the fault.
Elastic Rebound Theory
Gradual build up of stress along a fault until the strength of the
rock is
exceeded, resulting in a release of energy in the form of an

earthquake
The Earthquake Cycle
• Change in strain
• Accumulation before an earthquake
• Drop after an event
• Three or four stages
1. Long period of inactivity
2. Accumulated elastic strain produces small earthquakes
3. Foreshocks
• Hours or days before large earthquake
• May not occur
4. Mainshock
• Major earthquake
• Includes aftershocks: few minutes to a year after
Elastic Rebound
Rocks deform elastically until a
critical point is reached and the
fault slips, releasing the stored
elastic energy

Time 1
Time 2
Time 3
Time 4
The Earthquake Cycle, cont.
• Epicenter
• Given by news reports
• Location on surface
above the rupture
• Focus (hypocenter)
• Point of initial breaking
or rupturing
• Displacement of rocks
starts here
• Propagates up, down,
and laterally along the
fault plane
• Produces shock waves,
called seismic waves
(cause ground shaking)

Seismic Waves
• Caused by a release of energy from rupture of a fault
• Body waves: travel through the body of the Earth
• P waves, primary or compressional waves
• S waves, secondary or shear waves
P waves, primary or compressional waves
- Body waves, travel through the body of the Earth
P waves, primary or compressional waves
- Velocity depends on density
and compressibility of the
materials through which they

pass
- Greater resistance to
compression, greater the
velocity
- Seismic waves pass
through packed atomic
structures
- Velocity through igneous rocks
(eg. granite) ~5.0 km/s
- Velo. in sed. rocks (eg.,
sandstone) ~3.0 km/s
S waves, secondary or shear waves
- Body waves, travel through the body of the Earth
S waves, secondary or shear waves
- Transverse waves that

propagate by shearing
particles at right angles to the
direction of propagation in the
vertical and horizontal plane
- Velocity depends on density
and resistance to shearing of
materials
- Velo. in igneous rocks ~ 3.0
km/s
- Velo. in sedimentary rocks ~1.7
km/s
Surface waves: move along
Earth’s surface
surface

waves
• Complex horizontal and vertical
ground movement
Rayleigh Waves
• Rolling motion
• Responsible for most of the
damage near epicenter
• Shaking produces both
vertical and horizontal
movement
Surface waves: move
along Earth’s surface
surface
waves
• Complex horizontal and
vertical ground movement
Love Waves

• Horizontal ground shaking
• Faster than Rayleigh
waves
• Do not move through water
or air
• Very hazardous!
Wave direction
Seismic Waves and Wave Attributes
• Amplitude: height of wave
• Wavelength: distance between successive wave peaks
• Period [s]: time between wave peaks (= 1/frequency)
• Frequency [Hz]: number of wave peaks in one second
Seismic Waves and Wave Attributes
• Attenuation: amplitude of seismic waves decreases with
increasing distance from the hypocenter

- More pronounced for high-frequency waves
- Less pronounced for low-frequency waves
How do we detect and record seismic waves?
Horizontal component Vertical component
Before computers…
Modern 3-component seismograph station
3 orthogonally aligned seismometers:
- Veritcal
- North-south
- East-west
Seismogram
(a recording of the ground motion)
P
S
Analysis of seismic
records allows

seismologists to
identify the different
kinds of seismic
waves generated by
fault movement
Distance to Epicenter
Use difference between first P and S wave arrival times:
- P waves will appear first
- Seismographs across globe record arrivals of waves to station
sites
- Distance to epicenter can be found by comparing travel times
of the
waves
Distance to
Earthquake
Epicenter
Note:

P-wave first
S-wave second
Surface waves last
Time lag between P and S-wave
arrival is called Δt, or the S-P time.
Ex. 1994 M 6.7
Northridge earthquake
Calculating Epicentral Distance
P wave has velocity VP ; S wave have velocity VS
VS < VP
Both originate at the same place – the hypocenter – and travel
the same distance, but
the S wave takes longer to arrive than the P wave.
Time for S wave to travel a distance D:
Time for P wave to travel a distance D:
The time difference between them is:
Now solve for the distance D:

Time =
Distance
Velocity
T
S
=
D
V
S
T
P
=
D
V
P
(T
S
-T
P
) =
D
V
S
-

D
V
P
= D
1
V
S
-
1
V
P
æ
è
ç
ö
ø
÷ = D
V
P
-V
S
V
P
V

S
æ
è
ç
ö
ø
÷
� =
��
�� − ��
�� − ��
Locating an Earthquake
• Location of epicenter
• At least three stations
are needed to find
exact epicenter
• Distances from
epicenter to each
station are used to
draw circles
representing possible
locations
• The place where all

three circles intersect
is the epicenter
• Process is called
triangulation
Tectonic Creep and Slow Earthquakes
• Tectonic creep: gradual movement such that
earthquakes are not felt
- Can produce slow earthquakes
- Also called fault creep
• Can slowly damage roads, sidewalks, and building
foundations
• Can last from days to months
https://seismo.berkeley.edu/blog/2008/10/14/the-hayward-
fault.html
https://seismo.berkeley.edu/blog/2008/10/14/the-hayward-
fault.html
Earthquake Shaking
• Shaking experience depends on:
1. Earthquake magnitude

2. Location in relation to epicenter and direction of rupture
3. Local soil and rock conditions
• Strong shaking from a moderate magnitude or higher
CH. 2 – INTERNAL STRUCTURE OF THE EARTH
AND PLATE TECTONICS
Learning Objectives
theory of
plate tectonics.
Earth’s
surface over time.
drive plate
tectonics.

Learning Objectives
theory of
plate tectonics.
Earth’s
surface over time.
drive plate
tectonics.
Lithospheric Plates of the World
• California straddles the
boundary between two
tectonic plates
• San Andreas fault: boundary

between North American and
Pacific plates
• Los Angeles and San Francisco
located on opposite sides of the
fault
• Movement of San Andreas
fault in 1906
• Caused major earthquake
• Earthquakes not understood at
the time
• Scientific investigations led to
identification of fault and new
understanding of earthquakes
Topography is shaped
by Plate Tectonics!
Two cities on a Plate Boundary, cont.
• San Andreas fault system
- Many moderate to large earthquakes in Los Angeles on this
fault

- Mountain topography in coastal California result of fault
- Earthquakes since 1906 have cost hundreds of lives and
billions of dollars in property damage
• Future of the fault
- Los Angeles and San Francisco will be side by side in 20
million years
- May be a shift in the plate boundary and a change in the
topography
Origin of the Sun and Planets - Solar Nebula
• The sun and planets were born from a rotating disk of cosmic
gas and dust,
the solar nebula
• The flattened form of the disk constrains the planets:
- To move in the same direction as the disk
- To have their orbits in the same plane
Planetary accretion
Accretion stages:

1. Accretion into miniature planets (diameter < 1 km)
2. Collisions between miniature planets form a few large planets
• All planets formed at the same time (~4.6 billion years ago)
Earth’s Early History
Heat-generating processes during the formative years of the
Earth
cause differentiation
Differentiation
Differentiation: process by which gravity causes denser
material to gradually migrate to the center of a planet
Density increasing
from surface to
center
www.phys.org

The Geoid
The shape that the surface of the oceans would
take under the influence of Earth’s gravity and
rotation alone
Surface of the Earth
Land
Model of the Earth
Sea
Geoid Ellipsoid
Differentiation of the Earth
Earth is differentiated
into layers based on:
- Density
- Strength
www.phys.org
Internal Structure of Earth

• Internal processes have incredibly important impacts
on the surface of the Earth
• Responsible for continents and ocean basins
• Oceans’ currents and distribution of heat carried by seawater
controlled by configuration of continents and ocean basins
• Responsible for regional landforms
• Earth is layered and dynamic
• Internal structure of Earth
• By composition and density
• By physical properties (strength)
Earth and its Interior
Layers based on density
Crust:
Silicon & Oxygen
Mantle:
Iron & Magnesium
Outer core:

Liquid iron
Inner core:
Solid iron
Crust:
Silicon & Oxygen
Mantle:
Iron & Magnesium
Outer core:
Liquid iron
Inner core:
Solid iron
Less dense
Dense
Very dense
Internal Structure of Earth,

cont.
Earth’s structure:
• Outer core
- Liquid
- 2,000 km (1,243 mi.) in thickness
- Composition similar to inner core
- Density (10.7 g/cm3)
• Inner core
- Solid
- 1,300 km (808 mi.) in thickness
- High temperature
- Composed of iron (90 percent by
weight) and other elements (sulfur,
oxygen, and nickel)
The core is a
“heat battery”
• The Earth is cooling down

• Cooling of the liquid outer core
• The inner core is growing over
time as the outer core cools
and solidifies!
• Tremendous heat is given off
as the liquid outer core
solidifies and the inner core
cools. >10,000 Giga-watts!
Internal Structure of
Earth, cont.
• Mantle
- Solid
- 3,000 km (1,864 mi) in
thickness
- Composed of iron- and
magnesium-rich silicate
rocks
- Average density 4.5 g/cm3
• Crust
- Outer rock layer of Earth

- Density 2.8 g/cm3
- Moho discontinuity
- Separates lighter
crustal rocks from more
dense mantle
Thin crust rich in silicon
and oxygen
Magnesium- and iron-
rich mantle
Iron-rich metallic core
Continental crust is
thicker and less dense
than oceanic crust
Continental vs. Oceanic Crust
Continental Crust
• Average thickness:

35-70 km
• Less dense
• Older (up to 4 Ga)
• Typically composed of
granite
Oceanic Crust
• Average thickness: 6-
7 km
• More dense
• Younger (less than
200 Ma)
• Typically composed of
basalt
Material Deformation
• When materials are subjected to external forces, stress,
they deform or undergo strain
• Stress applied perpendicular => stretching under tension,

or contraction under compression
• Shear stress =
parallel to surface
Material Deformation - responding to stress
Internal Structure of Earth, cont.
The outer surface of the Earth consists of several
lithospheric plates moving relative to each other as rigid
bodies on a fluid substratum called the asthenosphere
• Lithosphere
- Cool, strong outermost layer of Earth (crust and upper mantle)
- Crust embedded on top
• Asthenosphere
- Below lithosphere
- Hot, soft/ductile slowly flowing layer of weak rock
- Higher water content and hotter

Layers based on Strength
Gaseous atmosphere
Liquid hydrosphere
Rigid lithosphere
Soft plastic asthenosphere
Stiff plastic mesosphere
Liquid outer core
Solid inner core
The boundary between lithosphere and asthenosphere not
defined by
a difference in chemical compositions, but in mechanical
properties
(i.e. the rigidity of the material, how the material deforms under
stress).
CONTINENTAL
PLATE
OCEANIC

PLATE
MANTLE LITHOSPHERE
CRUSTAL
LITHOSPHERE
ASTHENOSPHERE
Tectonic plates are lithospheric plates
Tectonic plates
are lithospheric
plates “floating”
on top of the
asthenosphere
Lithosphere –
asthenosphere
boundary at a
depth of ~100 km
Buoyancy
• Earth can be described as a series of layers where less dense

material floats on top of denser material
- Low-density crust floats on top of the denser mantle
- Mantle floats on top of the very dense core
root
load
Isostasy
Surface elevation represents a balance between forces:
- Gravity : pushes plate into mantle
- Buoyancy : pushes plate back to float higher on mantle
Isostatic equilibrium describes this balance.
Isostasy is compensated after a disturbance.
Adding weight pushes lithosphere down
Removing weight causes isostatic rebound
Compensation is slow, requiring asthenosphere to flow.
root
load
Isostasy in Canada

• ~18,000 years ago,
Canada was buried under
a continental glacier with
ice thickness ~5 km
around Hudson Bay
• The weight of the ice
sheet caused the land to
sink more than 1 km
• 10,000 years ago the ice
sheet had melted and
retreated
Heat Transfer
Heat can be transmitted through solids and fluids by
conduction, through fluids by convection, and by radiation.
Heat Transfer
On a planetary scale, the same processes are active!
- Heat from the interior of Earth flows
to the surface by conduction
- In the mesosphere and

asthenosphere, heat is redistributed
by flow of plastic solids
- Hot, less-dense materials rises
- Cold, denser material sinks creating
convection cells
• Convection
- Earth’s internal heat causes magma to heat up and become less
dense
- Less dense magma rises
- Cool magma falls back downward
• Convection
- Earth’s internal heat causes magma to heat up and become less
dense
- Less dense magma rises
- Cool magma falls back downward

How do we infer the structure of the Earth?
How do we infer the structure of the Earth, cont.
• Seismology!
- Study of earthquakes
- Information on wave movement
• Earthquakes cause seismic energy to move through Earth
(more later)
- Some waves move through solids, but not liquids
- Some waves are reflected
Incident ray
Reflected
ray
How do we infer the structure of the Earth, cont.
• Seismology!
- Study of earthquakes
- Information on wave movement

• Earthquakes cause seismic energy to move through Earth
(more later)
- Some waves move through solids, but not liquids
- Some waves are reflected
- Some waves are refracted
Global seismic observations
Quick intro. - Seismic waves
P waves (Primary waves): compressional motion, 6-8 km/s
S waves (Secondary waves): shear motion, 3-5 km/s. Do
not pass through liquids
Surface waves: travel along surface of earth, < 3-4 km/s
S-waves and the outer core
• S-waves do not propagate in a liquid
• Liquid cannot support shear motions
• This is how we infer that the outer core is liquid

• S-waves do not propagate through the outer core
Seismic Shadow Zones
Seismic tomography can also tell us the locations
of hot and cold regions in the mantle
(credit: Global Seismology Group / Berkeley Seismological
Laboratory)
ERTH 2415 : Natural Disasters
Course Information – Welcome!
Video lectures and course content were created by Mareike
Adams
Course Instructor:
Samuel Morton ([email protected])
Office hours: Thursdays 10:00 – 11:00, in HP 2125
Teaching Assistants:

Naomi Weinberg ([email protected])
Office hours: Mondays 2:00-3:00 PM in HP2125
Nabil Shawwa ([email protected])
Office hours: Tuesdays 1:00-2:00 PM in HP2125
Yingzhou Li ([email protected])
Office hours: Wednesdays 1:00-2:00 PM in HP2125
Please visit or email us if you have any questions/concerns!
mailto:[email protected]
Lectures & CUOL
CUOL Web Channel
The CUOL Web Channel will play a recorded video of the
lecture on their web
channel:
https://vod.cuol.ca/stream/web-channel
Initial Show Time: Mondays at 1:00 PM – 3:45 PM EST
Repeat Show Time: Tuesdays at 1:30 AM – 4:15 AM EST
Video on Demand (VOD)

For a $50 subscription fee, you can access the recorded videos
of the lectures
at any time. You can also rent individual lectures for $6 each.
https://vod.cuol.ca/vod
CUOL Student Centre (Loeb D299)
The CUOL Student Centre has kiosks available to view each
lecture for free,
available 24 hours a day, 7 days a week.
Lectures can also be freely viewed on campus using computer
terminals, such
as those found at the MacOdrum Library.
https://vod.cuol.ca/stream/web-channel
CUOL Information and Assistance
CUOL website: www.carleton.ca/cuol
Video On Demand login page: https://vod.cuol.ca/vod
CUOL Student Centre: D299 Loeb, 613-520-4055
General Information:
Email: [email protected]
Video on Demand support and questions:

Email: [email protected]
http://www.carleton.ca/cuol
Course Information
Optional Texts:
Natural Hazards, 4th or 5th Edition, Edward A. Keller & Duane
E. Devecchio
OR
Natural Disasters – Canadian Edition, 4th edition, Abbott, P.L.
and Samson, C. 2015
Grading:
Quizzes:
• 4 quizzes – 5% each – multiple choice
• Each will take ~30 min to 1 hr. You will have 3 hours.
• Open on CuLearn for 4 days – but you only have 1 chance to
complete it
• Once you have started the quiz it will be open for the allotted
time – closing the
browser will not stop the clock!
Quizzes: 20%

Midterm Exam: 40%
Final Exam: 40%
Course Information
Quiz breakdown:
Quiz 1 : Lectures 1-3
Quizzes:
• After you finish a quiz, you can immediately see how you
scored – but
not the questions you missed
• Open book – but you cannot do them in groups!
• Should you experience problems during your Quiz:
• Note the time
• Take a screenshot of the problem
• No accommodation will be made to waive or redo a Quiz
unless supporting or
substantiating documentation is provided

Course Information
Grading:
Exams:
• Midterm Exam will occur on February 29th from 2:30 – 4:30
pm
• Lectures 1-5
• Final Exam will occur during final exam period (Date/Time To
Be Announced)
• Lectures 6-11
• Local students, living within 100km of Carleton, write their
exams on campus.
• Distance students, living over 100km from campus, will write
exams at either
a Carleton University Test Centre or may apply to write the
exam at distance
with a proctor. Distance students should apply through CUOL
immediately.
Quizzes: 20%
Exam 1: 40%
Exam 2: 40%

NO questions/emails
regarding exams will
be answered on the
day of the actual exam
Course Timeline for Winter 2020
Offshore British Columbia–Southeastern Alaska
2017 Mw 7.1 earthquake, central Mexico
Hurricane Harvey – Category 4
Credit: NASA/NOAA GOES Project
Hurricane Irma – Category 4
Hurricane Maria – Category 4
2017 Hurricane Patterns

Hurricane Harvey – Category 4
Credit: NASA/NOAA GOES Project
Hurricane Irma – Category 4
Hurricane Maria – Category 4
Is this normal??
Hurricane Sandy (2012)
Map by Robert Simmon, using
data from the NOAA Earth System
Research Laboratory
Course Objectives
• Demonstrate a comprehension of Earth’s geologic, hydrologic
and atmospheric processes
• Identify the cause and effect relationships between earth
processes and natural hazards
• Assess the associated risks of natural disasters on human
societies and identify when a hazard becomes a catastrophe
• Discuss if and how geological catastrophes can be predicted,
mitigated, and avoided

• Develop and apply skills in scientific observation, data
interpretation and critical thinking
Why Studying Natural Hazards is Important
• Have experienced large, costly, and deadly natural hazards
since 1995
• Deadliest tsunami caused by earthquake in Indian Ocean
• Tsunami in Japan caused by largest and costliest earthquake in
recorded history
• Catastrophic flooding in different areas of the world
• Volcanic eruptions that shut down international airports
• Worst tornado outbreak in U.S. history
• Etc.
Forgan,
Oklahoma
Processes: Internal and External
• Processes
• Physical, chemical, and biological ways in which events

affect Earth’s surface
• Internal processes come from forces within Earth
• Plate tectonics
• Result of internal energy of Earth
• External processes come from forces on Earth’s
surface
• Atmospheric effects
• Energy from the Sun
Hazard, Disaster, or Catastrophe
• Hazard
- Natural process or event that is a potential threat to human
life or property
• Disaster
- Hazardous event that occurs over a limited time in a
defined area
- Criteria:
1) Ten or more people killed
2) 100 or more people affected
3) State of emergency is declared
4) International assistance is requested
• Catastrophe
- Massive disaster that requires significant amount of money

or time to recover
Natural Disaster ?
A large earthquake occurs:
- In Vancouver:
- On an Arctic Island:
YES
NO
Natural Disaster ?
- In Vancouver: YES
- On an Arctic Island: NO
Misnomer
- Gives the impression that disasters are only the
fault of nature
- “Natural” disasters often triggered when society
ignores natural hazards

Natural Hazard?
- In Vancouver:
- On an Arctic Island:
A source of danger that exists in the environment
and that has the potential to cause harm.
- Potentially damaging
- Ex. unstable snow on a mountain slope, high water
levels, etc.
YES
YES
Some Major Hazards in Canada
Major Hazards in the United States
Hazard, Disaster, or Catastrophe, cont.

• During past half century, there has been a dramatic
increase in natural disasters :
- Examples: Haitian earthquake, Indonesian tsunami,
Hurricane Katrina
• United Nation: 1990’s “International Decade for
Natural Hazards Reduction”
- Mitigation
• Reduce the effects of something
• Natural disaster preparation
Numbers, Effects, and Causes of Worldwide
Natural Disasters
Natural Disasters
• Storms attain category 3 wind speeds
~9 hrs faster than in 1980s
• Global wind speeds have increased

by ~5% over last 20 yrs
• In ground-based records, ~76% of
weather stations in the USA have
seen increases in extreme
precipitation since 1948
• Rainfall totals from tropical cyclones
in North Atlantic have risen at a rate
of 24%/decade since 1988
• Twice as many extreme regional
snowstorms between 1961-2010 than
1900-1960 (William Lau, NASA’s
Goddard Space Flight Center)
• In 2005, Atlantic hurricanes are ~60%
more powerful than in the 1970’s
(Kerry Emanuel, MIT)
Natural Disasters

Asia is particularly vulnerable,
why?
Death and Damage caused
by Natural Hazards
• Effects of hazards can differ and change
with time because of changes of
patterns of human land use
• Natural hazards that cause the greatest
loss on human life may not cause the
most property damage
• Hazards vary greatly in their ability to
cause catastrophe
Prediction:
Where would you expect the greatest
damage/economic losses from natural disasters?

A. Poorest nations
B. Developing nations
C. Industrial nations
World Disaster Damage ($$)
0
100
200
300
400
500
Poorest nations Developing nations Industrial nations
Source: ICLR, based on data from International Red Cross
P. Kovacs, Institute for Catastrophic Loss Reduction, 2005
US$ billions (2000 prices),1991-2000
Prediction:
Where would you expect the greatest death toll from

natural disasters?
A. Poorest nations
B. Developing nations
C. Industrial nations
World Disaster Fatalities
0
100
200
300
400
Poorest nations Developing nations Industrial nations
Thousands of people, 1991-2000
Source: ICLR, based on data from International Red Cross
P. Kovacs, Institute for Catastrophic Loss Reduction, 2005
Earthquake in Haiti, 2010: A Human-Caused
Catastrophe?

• Earthquake became a
catastrophe
• Eighty-five percent of people in
Port-au-Prince lived in slum
conditions
• Poor conditions lead to 190,000
destroyed or damaged homes
• Killed a quarter million people
• Two million homeless with poor
sanitation and water quality
• Reason for catastrophe was
clear: heavy human footprint
• Large number of poorly
constructed buildings
• Population grew so fast
High death totals often related to economic and political factors
Earthquake in Haiti, 2010: A Human-Caused
Catastrophe?
Reason for catastrophe was clear: heavy human footprint
• Large number of poorly constructed buildings
• Population grew so fast
• 90% of mountainous regions have been deforested

• Dry, exposed land can easily emphasize massive floods +
landslides
Natural Hazards and the Geologic Cycle
• Natural hazards are repetitive
• History of an area gives clues to potential hazards
- Maps, historical accounts, climate and weather data
- Rock types, faults, folds, soil composition
• Geologic conditions govern the type, location, and intensity of
natural processes
• Collectively, processes are called geologic cycle
- Subcycles:
• Tectonic cycle
• Rock cycle
• Hydrologic cycle
• Biogeochemical cycle
The Tectonic Cycle
• Refers to large-scale processes that deform Earth’s crust
and produce landforms

• Driven by forces within Earth (internal energy)
• Involves the creation, destruction, and movement of
tectonic plates
The Rock Cycle
• Rocks are aggregates of one or more minerals
• Recycling of earth materials linked to all other cycles
- Tectonic cycle: heat and energy
- Biogeochemical cycle: materials
- Hydrologic cycle: water for erosion and weathering
• Rocks classified according to how they were formed
in the rock cycle
The Rock Cycle, cont.
• Igneous rocks
- Form from crystallization of magma
• Sedimentary rocks
- Rocks are weathered into sediment by wind and water

- Deposited sediment undergoes lithification
• Metamorphic rocks
- Rocks are changed through extreme heat, pressure, or
chemically active fluids
The Rock Cycle
The Hydrologic Cycle
• Movement of water between atmosphere and oceans
and continents driven by solar energy
• Processes include: evaporation, precipitation, surface
runoff, and subsurface flow
• Water is stored in compartments such as oceans,
atmosphere, rivers, groundwater, etc.
- Residence time is estimated average time that a drop of
water spends in any compartment
- Only a small amount of water is active at any given time

Hydrologic Cycle
Biogeochemical Cycle
• Transfer of chemical elements through a series of
reservoirs
- Atmosphere, lithosphere, hydrosphere, biosphere
• Related to the three previous cycles
- Tectonic cycle: water from volcanic processes; heat and
energy
required
- Rock and hydrological cycles: involved in transfer and storing
of
chemical elements
• Rates of transfer of important chemical elements are only
approximate
- Carbon, Nitrogen, Phosphorus
The World’s Water Supply (selected examples)
Fundamental Concepts for Understanding
Natural Processes as Hazards
1. Hazards are predictable from scientific evaluation

2. Risk analysis is an important component in our
understanding of the effects of hazardous processes
3. Linkages exist between different natural hazards
as well as between hazards and the physical
environment
4. Hazardous events that previously produced disasters
are now producing catastrophes
5. Consequences of hazards can be minimized
1. Hazards are predictable from scientific evaluation
• Location: Where might the event occur?
- Most hazardous areas are mapped
• Probability: How likely is it that the event will occur?
- Estimated based on past events and current conditions
• Precursor events: Could any recent events be a precursor for
something else?
Forecast vs Prediction
• Prediction
- Specific date, time, and magnitude of event
• Forecast

- Range of probability for event
Most hazards can only be forecasted
2. Risk Analysis
Risk = (probability of event) x (consequences)
→Live in northern Saskatchewan?
→Live inside the crater of an active volcano?
→Live on the San Andreas fault?
Consequences: damages to people, property, economics, etc.
Acceptable Risk is the amount of risk that an individual or
society is willing to take
Problem: lack of reliable data for either the probability or
consequences
3. Linkages
Hazards may be linked to or cause one other
Hazards linked to earth materials
For example:

• Earthquakes can cause landslides
• Earthquakes and landslides can cause tsunamis
• Volcanic eruptions may be preceded by earthquakes
• Hurricanes can cause flooding
• Drought can make fires worse
• Global warming (climate change) could lead to more
hurricanes
• Some rock types are prone to landslides
4. Disasters are now becoming Catastrophes
The world’s population is growing exponentially
• Grows by the addition of a constant percentage
of current population
• Has more than tripled in the past 70 years
The Problems:
• Increases number of people at risk
• Reduced availability of food & clean drinking water
• Greater need for energy and waste disposal
Examples:

Mexico City: 10,000 killed in 1985 8.0 earthquake
Izmit, Turkey: >17,000 killed in 1999 earthquakes
20th Century rapid rise in human population
Why does the frequency of natural disasters appear to
be increasing?
Has the frequency of natural hazards increased as well?
Great Natural Disasters 1950-2008
Number of Earthquakes M≥7.0 per Year
Number of Earthquakes M≥7.0 per Year
The number of earthquakes isn’t increasing
The population is!
Magnitude and Frequency of Hazardous Events
• Impact of hazards depend on:

- Magnitude: Amount of energy released (how large is the
event)
- Frequency: Interval between occurrences
- Other factors: climate, geology, vegetation, population, and
land use
• Magnitude-frequency concept
- Frequency of an event inversely related to magnitude
• Land use affects magnitude and frequency of events
Metrics to describe hazard levels: Frequency
• Number of similar events per unit time
• Example:
- On average, 4 former tropical cyclones affect
Atlantic Canada every year
- Frequency = 4 occurrences per year
Metrics to describe hazard levels:
Return Period
• Length of time between similar events

• Example:
- Severe hurricanes strike the US on average every
6 years
- This does not mean that there is a severe
hurricane exactly every 6 years!
Metrics to describe hazard levels: Magnitude
• Amount of energy fuelling a natural event
• Example:
- Force of hurricane winds
- Amplitude of ground motion during an earthquake
- Amount of water flowing in a river during a flood
Frequency and Return period
• Two ways to express the same facts:
- Frequency and return period are the inverse of one another
• Ex. Spring and fall heavy rains occur twice a year (frequency)
- So, every ½ year, spring and fall heavy rains occur

Low-magnitude events occur frequently (have a short period)
High-magnitude events are rare (have a long return period)
Frequency =
1
period
Period =
1
frequency
Frequent occurrences are low in magnitude; rare occurrences are
high in
magnitude
The larger the event, the longer the return period (recurrence
interval)
In general, inverse
correlation between
frequency and
magnitude of a process
5. Consequences of Hazards can be Minimized
• Primarily reactive in dealing with hazards

- Search and rescue
- Firefighting
- Providing emergency food, water, and shelter
• Need to increase efforts to anticipate disasters and their
effects
- Land-use planning limitations
- Hazard-resistant construction + building codes
- Hazard modification or control
- Disaster preparedness (e.g. Evacuation plans, insurance)
- Control through artificial structures
• Total losses are direct losses and losses related to human
actions
5. Consequences of Hazards Can Be Minimized:
Reactive Response
• Effects from a disaster can be
▪ Direct (felt by fewer individuals): people killed or
dislocated, buildings damaged, etc.
▪ Indirect (affect many more people): emotional distress,
donation of money or goods, taxes for recovery, etc.
• Recovery from disaster
▪ Emergency work
▪ Restoration of services and communication lines
▪ Reconstruction

Reducing Risk –
four pillars of emergency management
1. Response Short-term
- Immediate actions to put event under control
2. Recovery Middle-term
- Put situation back to normal
3. Mitigation Long-term
- Actions taken to minimize risk, damage
4. Preparedness Long-term
- Actions taken in advance to ensure people are ready
• New term added in response to climate change issues
- Adaptation Long-term
Potential Natural Disasters in
the Near Future:
“The Big One” (2015-2045)
• The US Geological

Survey’s Third Uniform California
Rupture Forecast (UCERF3)
predicts earthquake eruptions
and states that a magnitude 8.0
or larger earthquake has a 7
percent chance of occurring in
the next 30 years, at present.
• The odds of a magnitude 6.5–7.0
earthquake hitting went up 30
percent.
Wildfires in Canada and the United States
(2015-2050)
• Environmental scientists from
the Harvard School of
Engineering and Applied
Sciences (SEAS) predict that
by 2050, wildfire seasons will

be three weeks longer, twice as
smoky, and will burn a larger
portion of the West per year
• 30,000–50,000 wildfires
predicted to occur annually
Q: What has led to this dramatic increase in wildfire risk?
Canadian Trends
• The # of natural disasters
is increasing with time
• Communities are increasingly
vulnerable:
• Population growth
• Development in risky areas
• Degradation of natural
ecosystems
• Over-reliance on technology

Canadian Trends
• The # of natural disaster
fatalities is decreasing with
time
• Economic losses are mostly
due to weather-related
disasters
• Improved engineering
• Long-term prevention
• Extensive disaster
education
• Better warning systems
• Rapid response
Forecast, prediction, and warning of
hazardous events
• Uniformitarianism
- “The present is the key to the past”

• Human interaction has an effect on geologic processes
- “The present is the key to the future”
• Environmental Unity
- One action causes others in a chain of actions and events
Remember!
“Natural hazards are inevitable, but
natural disasters are not!”
… and the Oscar goes to …
… and the Oscar goes to …

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