Activity 1.1:
Defining Hazard and Risk
This work is supported by a National Science Foundation (NSF) collaboration between the
Directorates for Education and Human Resources (EHR) and Geociences (GEO) under grant DUE - 1125331
Hazard or Risk?
1. In this cartoon,
what are the
hazards?
1. How could the
parachutist
minimize her risk
from these
hazards?
Geologic Hazards
• Phenomena capable of causing harm to humans
–
–
–
–
–
–
–
Tsunami
Flood
Volcanic ash
Lahar
Fire
Liquefaction
Landslide
Primary Hurricane Hazards
- Wind
- Storm Surge
- Rain
- Waves
Secondary Hurricane
Hazards
(caused by a primary hazard)
- Flooding
- Fire
- Landslides
- Coastal Erosion
…. Can you think of others?
Risk
• The likelihood and cost of a hazard
happening to you
• Factors:
– Cost
• human life
• damage to property and infrastructure
– Probability
• dependent on location
• large events are generally less likely than small ones
Activity 1.2:
Jared Diamond’s 2013 essay,
“That Daily Shower Can Be A
Killer”
This work is supported by a National Science Foundation (NSF) collaboration between the
Directorates for Education and Human Resources (EHR) and Geociences (GEO) under grant DUE - 1125331
Activity 1.2 In-Class Questions
• What do you think is the natural hazard you
encounter most frequently? Is it the one from
which you perceive the most risk?
• Thinking of Diamond’s example of New
Guineans not sleeping under dead trees, what
is at least one thing we do as a society to
reduce risk to the natural hazard you listed
above?
Activity 1.3:
Calculating Hurricane Risk
This work is supported by a National Science Foundation (NSF) collaboration between the
Directorates for Education and Human Resources (EHR) and Geociences (GEO) under grant DUE - 1125331
How is Risk Defined?
Risk = Likelihood x Cost
Likelihood Examples
1. California has had 8 major (magnitude>7)
earthquakes in the last 100 years. That is
about 12 years between major hurricanes, on
average (also called the return period). So
the likelihood of a major earthquake
somewhere in the state is 8% each year.
2. The return period of landslides on Smith Lane
is 5 years. The likelihood of a landslide on
Smith Lane this year is 20%.
When the “Return Period” is low,
the likelihood is high.
Which state would you expect to
be at higher risk of hurricane
landfall because of higher
likelihood, Florida or Maine?
(NWS)
Costs
• Human
• Property
• Infrastructure
– Can be difficult to quantify . . .
If you own a $1,000,000 house in coastal North Carolina and
rent a small apartment in coastal Texas, which holds a higher
hurricane risk?
NC, because of higher frequency AND higher cost
Summary
• Risk = Likelihood x Cost
• In other words . . .
– If the cost is very small or the likelihood is very
low, the risk will likely be low.
References
• Slide 2. Creative Commons License Illustration
by Richard J. King, 2012.
• Slides 10 and 12. NOAA Public Domain Image
http://www.nhc.noaa.gov/climo/.