Lecture 1 - Hazards
• Affect millions of people each year
• Within NA, every location is at risk from at least one hazardous process
o West coast – earthquakes, landslides
o Eat coast – hurricanes
o Mid – tornadoes & blizzards
o All areas – droughts
• Hazards pose risk to both humans and environment
• Technological Hazards
▪ Nuclear meltdown
▪ Toxic gas
▪ Oil spills
▪ Ozone depletion
▪ Acid rain
▪ Airplane crashes
Processes and Natural Hazards
Arise from 3 main processes
• Internal forces within earth
▪ Driven by earths internal energy
▪ Ex: plate tectonics
• External Forces
▪ Suns energy
▪ Ex: Atmospheric effects
• Gravitational Attraction
▪ Ex: downslope movement (landslide)
• Hazard: Process that poses a potential threat to people or environment
• Risk: Probability of an event occurring multiplied by impact on the people/environment
• Disaster: Event that causes great property damage or loss of life
• Catastrophe: Massive Disaster
o Tsunami – Thailand December 2004, Japan March 2011
o Hurricane Katrina 2005
o Earthquake – Haiti January 2010
o Oil Spill – Gulf of Mexico, April 2010
Hazards differ in potential to cause catastrophe
• More likely to be catastrophic: tsunamis, earthquakes, volcanoes, hurricanes, floods,
• Less likely: Landslides, avalanche, tornadoes
Magnitude and Frequency
• Impact of a hazard is a function of both its magnitude and frequency
• Can also be affected by other factors (land use, population, density) • Magnitude Frequency Concept: Inverse relationship between magnitude and frequency (one up,
• Ex: high mag earthquake, low frequency
• Clues for risk of hazards: maps, history, journals, Ariel photos, data, land features, weather and
climate data, craters, faults, valleys
• Earth is 4.6 billion years old
• Tectonic cycle, rock cycle, hydrologic cycle
• Creation, movement, and destruction of tectonic plates
• Tectonic Plates: large blocks of earths crust that form its outer shell; 14 of them
• New land is formed at mid-ocean ridges and land is destroyed at subduction zones
• All driven by earths internal energy
Earths Internal Structure
• Asthenosphere: upper mantle – composed of hot magma with some flow.
• Lithosphere – thin and brittle crust
• Crust forms upper part of lithosphere and broken into plates
• Two types of crust
o Oceanic – dense, thin (average of 7km thickness)
o Continental – buoyant, thick, (30km thickness)
** Application question **
When both plates come together, which plate would subduct?
- Oceanic plate would sink because it is denser
• Denser material goes under if the two meet
• Movement of plates driven by convection currents within mantle
• Continents of today used to be clusters in the super continent or Pangaea 250 million years ago
• Plate boundaries do not tend to match up with boundaries or continents or oceans
• The movement of plates causes dynamic events on Earth’s surface, especially at plate boundaries
• Types of plate boundaries: Divergent, convergent, transform
• Evidence for this includes current mountain ranges
• Divergence results in seafloor spreading and causes new oceanic ridges to form
o Plates move away from each other
o New land is created at these locations
o E.g. Atlantic Ocean getting wider by a few cm each year
• Convergent plates move toward each other
o Collisions involving oceanic crust and continental crust results in subduction zones
o Subduction zone: One tectonic plate moves under another tectonic plate and sinks into the
mantle as the plates converge
o Dense ocean plates sink and melted magma rises to form volcanoes
o Collisions involving two continental plates result in collision boundaries o Collision Boundaries: Two continental plates push together and form a mountain range
▪ Neither plates sink (e.g. Himalayas)
• Transform Boundaries result in plates sliding horizontally past each other
o Zone along which the movement occurs is called transform fault
o Eg: San Andreas Fault
o These areas are found away from plate boundaries
o They are usually spots where magma rises up from the mantle
o Magma erupting at the surface results in the formation of volcanoes
o String of islands usually means hot spot
o E.g. Hawaiian Islands
o Hot spot stays still, plates move, magma eruption forms islands, more islands form as plates move
throughout million of years
Rock Cycle: Group of interrelated processes that produce three diff rock types: Igneous (used to be
lava but cooled), sedimentary, and metamorphic (See rock cycle slide)
- In a given location, the types of rock gives clues to geological events in the past
Hydrologic cycle: movement and exchange of water among land, atmosphere, and oceans by
changes in state
o Solar energy drives movement of water among atmosphere, ocean, and continents,
o Residence time of a water molecule ranges from days in atmosphere to thousands of years
in the ocean
o Water molecule goes through its cycle back to ocean
Major Course Themes
Hazards can be understood through scientific investigation
o Scientists observe hazardous event and form explanations/hypothesis
o Knowing cause allows us to ID somewhere else and predict future
o Natural hazards are not in our control – we can only respond
o Best way to mitigate is to prepare
o Prediction: specific time, date, location, and magnitude
o Forecast: range of probability for the event
o Some hazards can be predicted, many can be forecasted
Understanding of hazardous processes is needed to evaluate risk
o Risk = probability of event x consequences
o Consequences: damage to people, property, environment
o Acceptable risk: amount of risk that an individual is willing to take
o Frequency of event: plays role in determining acceptable risk
Hazards are linked to each other and environment
o Earthquakes linked to tsunamis and landslides
o Hurricanes may cause tornadoes and flooding
o Some environments are linked to certain hazards o E.g. some rock types are more prone to landslides
Population growth and socio economic changes are increasing risk
o Human pop creates greater loss of life in disaster
o Population growth is putting greater demand on earth resources
o Rapid population growth is in developing countries – many hazards in these areas
o Human population reached 7 billion in late 2011
o India and china account for 1/3 of pop
o The human footprint: risk associated with hazards change as human development expands
o Ex: neighborhoods expand into hill sides and flood plains
o In Canada – property damage is increasing b/c we have more property
Consequences of Hazards can be reduced
o Direct effect of disaster: deaths, injury, displacement, people, damage to property
o Indirect effects: crop failure, starvation, emotional distress, loss of employment
o Reactive approach: search and rescue, emergency food, water, shelter, and rebuilding
o Proactive approach – adjusting prior to – land use planning, building codes, insurance,
evacuation planning, disaster preparedness, artificial control (flood walls)
Benefits of hazards Called natural service functions
o E.g. flooding provides nutrients for soil
o Landslides create dams that form lakes
o Volcanic eruptions creates new land
Climate change is currently most crucial environmental issue facing earth
o Natural processes will increase
o Ex: sea rises from melting will cause erosion and flooding
o Warmer oceans will cause more frequent hurricanes
Natural Service Function
Which mountain chain is the site of the continent-continent collision?
A: HIMALAYAS (EXAM ANSWER)
Lecture 2 – Documenting Disasters
Maintaining databases on disaster events can be difficult. Why?
- Disasters can co-occur (hurricanes cause floods, earthquakes cause landslides, etc.)
- Mortality can be difficult to count (famine, epidemics)
- A general lack of census taking in developing countries Identifying Disasters
Some people may consider certain events to be disasters while other people may not.
Examples: (nobody killed in any of these – disaster?)
- Eastern Canada 1998 Ice Storm
- Walkerton tainted water
- Canada/U.S. 14-hour power blackout
- Love Canal toxic waste spill
- Three Mile Island nuclear meltdown
Therefore, a specific definition of a disaster has been developed.
What events officially qualify as a ‘disaster’?
A threshold has been developed by the Centre for Research on the Epidemiology of Disasters (CRED):
- 100 or more people affected (injured, homeless)
- Government declaration of disaster
- Plea for international assistance
- At least 10 deaths / event
- Need one of these criteria to be a disaster
Exceptions to the CRED threshold:
- For droughts or famines at least 2000 people affected
- For technological disasters 5 or more deaths (we lower the threshold)
Disasters and Statistics
- Statistical data is reported in absolute terms (number of casualties, billions of dollars in
- The impact of losses is felt differently from one place to the next.
- Example: 10 fishers lost in a remote village of 200 people vs. 10 factory workers in a city of
- Therefore, statistics must be placed in a community/regional context
- We need to look beyond just the geographical outcome, we need to think about the impact
that is felt by the people
- We need to go beyond what the media tells us…10 deaths/2000 is more grave than
Media and Disasters
The media tends to concentrate on:
- Human Interest
- Visual Impact
- Events close to home
- Prioritize according to the North American perspective
In a study by Adams (1986), in terms of media attention, the death of one North American = the
3 eastern Europeans 9 Latin Americans 11 Middle Easterners 12 Asians
Disasters and Impacts
Impacts vary greatly by disaster type
- Earthquakes tend to cause more deaths
- Floods affect more people (homelessness) but have fewer casualties
- Droughts lead only to economic losses in developed counties but to lead to famine in developing
- Technological disasters are more likely to occur in industrialized countries.
- Most impacts have increased over time:
- property damage
- economics losses
- persons affected
- Impacts have not increased in equal proportions.
- Economic losses have increased at a faster rate than deaths.
- Why are disaster impacts increasing?
- Why are developing countries more affected?
- Answers to these questions can be found through case studies.
Example: Haiti Earthquake (2010)
- Haiti has been the poorest country in the western hemisphere for many years.
- The M7.0 earthquake occurred on Jan. 12, 2010.
- Epicenter was 25km from Port-au-Prince (capital) most buildings were destroyed
- Death toll is around 220,000
- Looking at Haiti in context - M 7.0 is strong but is not usually considered a severe threat, however
the death toll is around 220,000 and the country is still recovering
- The earthquake occurred along a transform fault.
- Destruction was enhanced by poor construction materials and a lack of building codes
- Landslides affected slums in the hillsides surrounding the city.
- Presidential palace – 2 floor of the palace collapse as did the prison allowing 4000 inmates to
- Urban Slum Ruin
- A lot of problems in Haiti, border from Haiti to Dominican Republic can be seen (Dominican
Republic side = green Haiti = desert)
Economy is so desperate that Haiti sold off its lumber (left hand side)
- the buildings had no standards, buildings were built on top of one another
- rescue teams were slow to start
- aftershocks continued the devastation
- nearly ½ population is under the age of 18
- it was difficult to securely distribute hygiene kits, water and other aid to the survivors
Reason for Increase in Impacts
- Approximately 1 billion people live on degraded land. o Land you can’t really do anything with
- Poverty and lack of land availability leads to unsustainable farming practices.
- Examples: Soil erosion, deforestation, clearing, mangroves out for monoculture
- Degraded land increases the impacts of the earthquake
- No thought put into sustaining Haitian land (pre-earthquake)
- Mangroves can protect land against storm surges
- Monocultures results in a lost of biodiversity
- Around the world, people are increasingly moving from rural areas to urban areas.
- Slums & Squatter settlements are rapidly growing in developing countries.
Vulnerability to Disasters
The vulnerability for a particular location is a function of its resiliency and reliability.
Resiliency: The rate of recovery from the occurrence of an event
Reliability: The frequency with which protective devices against disasters are able to withstand
BOTH of these tend to be lower in developing countries (Developing nations have low resiliency and
recovery, poor infrastructure, poor economy)
Risk Assessment: Involves estimating the likelihood that a particular event will harm human health
Risk Management: Involves deciding whether or how to reduce a particular risk and at what cost
- Risk is viewed by individuals as subjective.
- What we as individuals consider to be risky is based on our own probabilistic risk
- Risk assessments are not a modern phenomenon.
- Example: there are religious examples of risk assessment that aim to assess the risk to the
soul based on moral conduct
- The value of accepting Christianity outweighs the value of rejecting it because the risk of
rejecting it is too high.
- Moral weighing of pros and cons
- We tend to avoid the worst case scenario
- It is best to have at least 100 years of data.
- This amount of data is not available for several hazards (high magnitude earthquakes,
nuclear accidents etc.)
Economic Loss Data
- This is often less available than event data.
- Dollars must be constantly re-adjusted for inflation * A lot of disasters do not happen often enough to have substantial data
* Nuclear disasters have not been around for 100 years
R = P * L
(R = risk P = probability of hazard occurrence L = loss (economic, health etc.)
- Cumulative probabilities sum to 1 therefore we can read each probability as a percent.
- We say something has cumulative probability of 0.01, something that has a 1% chance of
Question: Based on the data above, what is the total overall property loss risk?
Risk for each (top to bottom):
.95 x 0 = 0
.03 x 10,000 = $300
.015 x 50,000 = $750
.005 x 100,000 = $500
Total possible loss is $1,550
Risk Analysis Event Tree
- These may be used when the event database is inadequate (too small).
- Chain of events leading to a disaster must be known
- Probabilities within the chain must be calculable • 99% chance there is no excess pressure in the pipeline
• 1% chance there IS excess pressure
• MUST get 3 yes to release gas
• Multiply the chain to get to the outcome probability
• With careful design and maintenance, a system such as a nuclear power plant or space shuttle can
achieve a high degree of technological reliability.
o The overall reliability of a technological system is the product of two factors.
o System reliability =
o Technology reliability x Human reliability
• Human reliability is usually LOWER than technology reliability and is difficult to predict.
• Suppose the technological reliability of a nuclear power plant is 95% and the human reliability is
• The overall system reliability is then 71% (0.95 x 0.75 x 100 = 0.71 or 71%)
• Even if we could make the technology 100% reliable, the overall system reliability (in that
example) would be 75%.
• (1.00 x 0.75 x 100 = 0.75)
• The dependence of even the most carefully designed systems on unpredictable human reliability
helps explain tragedies such as the Chernobyl nuclear power plant meltdown and the Challenger
and Columbia space shuttle explosions. Risk Analysis
• The greatest risks many people around the world face today rarely make the news media.
• The greatest risk factor leading to a reduction in life expectancy is poverty.
• Why? Poverty is linked to:
• Increase susceptibility to fatal disease
• Lack of access of health care
• Contaminated water supplies
The reduction of poverty would lead to increased life expectancy and improved human health.
Indirect benefits of reducing poverty:
- Stimulates economic development
- Reduces environmental degradation
- Improves human rights
• Risks and stats are generally not well perceived by people.
• Many people are not concerned with high-risk activities that are done voluntarily
• Examples: smoking (1 premature death per 2 smokers)
▪ Motorcycling (1/60 premature deaths)
Driving a Car (1/4200 premature deaths)
• Yet, the same people may be concerned about West Nile Virus (1 per 1 million) or airplane crashes
(1 per 9 million).
- We don’t want risk to be imposed on us, we want to control the risks (you cannot control a plane
but you perceive to be able to control your own car)
Risks from hazards are more accepted by people if the risks are perceived to:
- Be voluntary vs. imposed
- Be under our control vs. controlled by others
- Have clear benefits vs. little or no benefit
- Be natural vs. anthropogenic
- Be statistical vs. catastrophic
- Be familiar vs. exotic
- Affect adults vs. children
How can we become better at perceiving risks?
- Carefully evaluate what the media presents
- Compare risks (question is NOT ‘is it safe’ but rather ‘how risky is it compared to others?’)
- Concentrate on most serious risks to own health and don’t worry about risks which you have no
The Changing Nature of Risk
There has been a shift in the nature of risks over the last few generations:
- Shift from infectious diseases toward chronic degenerative diseases (Ex: AIDS)
- Accidents shift from being more common in the workplace to rare due to improved safety
regulations - Death tolls from natural disasters are generally lower than they were in the past (however there
are new risks like nuclear energy malfunction)
- As technology has advanced, it has introduced new hazard threats.
- Examples: nuclear power plants, chemical spills, pesticides, ozone depletion, acid precipitation
- Life expectancy is increasing We have a good ability to measure risks to our health
- This has resulted from many years of scientific research.
- There has been an increased role of government in risk assessment and risk management.
- Examples: there are departments specifically devoted to disaster relief, traffic safety, public
- There has been an increased involvement of laypeople in risk management decisions.
- Examples: Greenpeace, Sierra Club (these organizations pressure the government and people in
places of power)
- As countries transition from developing to developed, there are increased expectations from the
public on their government.
- This creates pressure on governments and sometimes these expectations of the people can be
unrealistic depending on the reach and wealth of the country.
Lecture 3 - Tsunamis
Tsunami is Japanese for “harbour wave”.
They are produced by the sudden displacement of water.
Events capable of triggering tsunamis:
- Earthquakes that uplift seafloor
- Volcano flank collapse
- Underwater volcanic eruption
Earthquakes can cause tsunamis in two ways:
- Displacement of the seafloor triggering a landslide that enters the water
- Generally an earthquake must be at least over 7.5 in order to trigger tsunami
Tsunamis develop in a 4-stage process.
Earthquake triggered Tsunami (4 step process)
Stage 1: Displacement of the seafloor sets waves in motion that transmit energy upward and
- When the waves reach the surface of the water they spread outward
Stage 2: The waves move rapidly across the open ocean (they can reach speeds of over 500 km/h).
- Spacing of the wave crest is very large (can be more then 100km)
The height (amplitude) of the waves is often small (less than 1 m).
- Passengers on ships in the ocean rarely notice tsunamis passing beneath them Stage 3: approaching shore
• As the tsunami approaches land, the water depth decreases. This results in the water ‘piling
up’ and causes these effects:
- Decrease in wave speed
- Decrease in spacing of the waves
- Increase in wave amplitude
Stage 4: impacts land
• Wave can reach heights of dozens of meters
• The wave speed at this time can be up to 50 km/h making them impossible to outrun.
- Some tsunamis, water first recedes from the shore and exposes sea floor
A tsunami event consists of a series of large waves reaching shore lasting for several hours.
Run-up: The maximum horizontal and vertical distances that the largest wave of a tsunami reaches
as it travels inland.
- Geographic area impacted by a tsunami
Type of Tsunami
Distant tsunami: A tsunami that travels thousands of kilometers across the open ocean.
- On remote shorelines across the ocean, reduced energy lessens its impact.
- Also called tele tsunamis
Local tsunami: Affects shorelines a few Km to 100km from its source
- Because of this short distance, local tsunamis provide little warning.