2. Reading Material
• 1. Understanding Your Risks: Identifying Hazards and
Estimating Losses
• 2. Multi-Hazard Risk Assessment and Vulnerability Study:
Project Impact, Culebra Inc.
• 3. Multi Hazard Identification and Risk Assessment
• 4. Living With Earth's Extremes
• 5. The Ten Most Wanted: A Search for Solutions to
Reduce Recurring Losses From Natural Hazards
All will be provided as pdf files on CD or on line.
3.
4. Risk Assessment
• Determining likely impacts of a hazardous
event
• Combines:
– Information on physical hazard
– Information on vulnerability
10. We may briefly touch on:
• Technologic hazards
• Biologic
• Fires
• Other
11. Numbers of Major Disasters
• The following two slides show some information
about natural disasters in an unusual way
• The first table shows type of disaster
• The second table is by 5-year periods
• Both tables show the number of occurrences of
disasters when damage exceeded 1% of annual GNP,
when more than 1% of a country’s population was
affected, when more than 100 deaths occurred
• Keep in mind that this is not total damage, population
affected, or deaths, but number of occurrences
16. What can you do with this
information?
• Reduce risk through:
– Mitigation
– Preparedness
– Warning strategies
17. What do you already know about
natural hazards in the
United States?
• Think about:
– Where hurricanes strike
– Where tornados occur
– Flood zones
– Seismic zones
– Coastal erosion
• Hazard-prone areas are generally well
known, but details often lacking
18. Natural Hazards
• Natural processes or events that existed
throughout Earth history, but have only
become “hazardous” when they have
negative impact on humans
• To put things in perspective, think of many
other natural processes or events that are not
“hazardous”
19. Anthropocentric Perspective
• Natural processes only called “hazardous”
when they threaten human life, health, or
interests, either directly or indirectly
• Actually has lead to “adversarial” style of
hazard management—natural processes are
seen as the “enemy” and efforts are made to
manipulate the environment into submission
20. Rapid Onset Hazards
• Catastrophic events
• Strike quickly but with devastating
consequences
• Large comet or meteorite impact
• Also earthquakes, flash floods, sudden
windstorms
21. Other end of time spectrum:
• Droughts can last decades
• Worldwide, droughts are the most
devastating natural hazard because of long
duration and large area affected
22. Technological Hazards
• Exposure to naturally occurring hazardous
substances
• Examples: radon, mercury, asbestos fibers,
coal dust
• Usually through use of these substances in
our built environment
23. Anthropogenic Hazards
• Human generated
• Pollution and degradation of the natural
environment
• Examples: acid rain, contamination of
surface and ground water, depletion of
ozone layer, global warming
24. Primary Effects
• Result from the event itself
• Water damage from a flood
• Wind damage caused by a cyclone
• Collapse of a building caused by ground
motion during an earthquake
25. Secondary Effects
• Result from hazardous processes associated
with, but not directly caused by, the main event
• Forest fires sparked by lava flows
• House fires caused by gas lines breaking during an
earthquake
• Disruption of water and sewage services as a
result of a flood
• Flood from dam failure during earthquake or
intense rains
26. Tertiary (and higher order) Effects
• Long term or even permanent changes
• Loss of wildlife habitat or “permanent”
changes in a river channel during a flood
• Regional or global climatic changes and
resulting crop losses after major volcanic
eruption
• Changes in topography or land elevation as
a result of an earthquake (1964 Alaska EQ)
27. How many people impacted?
• Last two decades of 20th Century:
• 3 million deaths world wide
• 800 million people suffered adverse effects
such as loss of property or health
28. Numbers of Events (Hazards)
• United Nations estimate, in the 1990’s
• Landslides—tens of thousands
• Earthquakes—tens of thousands
• Thunderstorms—1 million
• Floods—100,000
• Plus many thousands of tropical storms,
hurricanes, tsunamis, droughts, volcanic
eruptions
29. Cost of Natural Hazards
• World Bank estimate, in the USA:
• $40 Billion per year in physical damage
• Windstorms, floods, earthquakes alone cost
the USA $18 million per day
• What do you think is the costliest natural
hazard in the southeastern USA?
30. Vulnerability
• Status of people and property in an area
subject to hazards
• Depends on type(s) of hazards as well as
type of development
31. Vulnerability depends on:
• Obviously, living in a hazardous area
• Population density
• Scientific understanding of the area
• Public education and hazard awareness
• Early warning system
• Communication
• Emergency personnel
• Building codes
• Cultural factors—people’s response to warnings
32. Awful Truth
• Almost no one dies in the USA from
hurricanes, but property damage is extreme
• Tens or hundreds of thousands may die in
Bangladesh from a hurricane, but property
damage low
• However, besides the disparity in deaths,
the relative value of monetary losses is
much higher in developing nations
33. Poverty vs. Affluence
• Both can cause pressures on environment
• Extensive deforestation for fuel wood of
Haiti or lands bordering the Sahara desert
• Extensive development around San
Francisco Bay on filled land susceptible to
liquefaction during an earthquake
34. Human intervention can increase
vulnerability
• 1. Habitation of lands susceptible to hazards
(floodplains or deltas)
• 2. Increasing the severity or frequency of natural
hazards (agriculture leading to increased soil
erosion, groundwater withdrawal leading to
subsidence, levees increasing flood levels, global
climate changes leading to increased intensity and
frequency of hurricanes)
35. Hazard Assessment
• Where
• Magnitude
• Frequency
• Likely effects of occurrence
• Provide information to planners and
decision makers
• Usually means a map or maps
39. A Probability Map. Shows areas
with highest probability of
exceeding a certain magnitude of
ground motion during an EQ
40. Seismic risk map for USA
shows expected damage for
maximum EQ intensity. Map
does not indicate frequency.
41. Hazard Assessment Uses
• Decisions about evacuation or contingency
funding
• Decisions concerning levels of response and
readiness
• Land use and zoning
• Building codes
• Scientists use for early alerts and further
study
42. Risk Assessment
• Incorporates expected (predicted) economic
losses, injuries and deaths, and loss of
functioning of services
• Key is establishing the probability that a
hazardous event of a particular magnitude
will occur within a given time period
43. Social and Economic Aspects of Risk
• Locations of buildings, facilities, and
emergency systems in the community
• Their potential exposure to the physical
effects of the hazardous situation or event
• Vulnerability—potential loss of life, injury,
or loss in value—when subjected to those
physical effects
44. Probability and Risk
• Being exposed to earthquake hazards by
living in Southern California for seven
months carries the same risk of death as:
• Smoking 1.4 cigarettes
• Drinking 0.5 liters of wine
• Having a single chest X-ray
• All increase chance of death by 1 in a million
45. Another way to express risk
• In terms of cost
• Dollar value of damages
• Expected deaths and injuries
• Both methods help decision makers and
scientists compare and evaluate hazards, set
priorities, and decide where to focus
attention and resources
46. Goals of this course
• Increase awareness of natural hazards
• To recognize risks from natural hazards
• Identify specific locations and things at risk
• Understand management/policy/political
decisions (and be skeptical)
• Understand losses from hazards beyond $$
• Scientists must play greater role
