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Risk Assessment

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  1. Risk Assessment GEOL 4093 Dr. David M. Bush

  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. Risk Assessment • Determining likely impacts of a hazardous event • Combines: • Information on physical hazard • Information on vulnerability

  4. Risk Assessment Provides Estimates of: • Deaths and injuries • Property damage • Economic losses

  5. Risk Assessment Leads to: • Mitigation • Preparedness • Warning • All in attempt to reduce negative impacts of hazards

  6. Course Organization • Physical Processes (hazards) • Geologic • Meteorologic • Risk Assessment • Probability • Maps • Mitigation • Reducing damages • Preparedness

  7. Most risk assessment to date is actually better termed hazard assessment That is, the assessment of the physical phenomena themselves

  8. We’ll Concentrate on Natural Hazards • Geologic • Seismic (earthquakes, tsunamis) • Volcanic • Other (subsidence, mass wasting, expansive soils) • Meteorologic • Hurricanes • Northeasters • Tornados • Floods

  9. We may briefly touch on: • Technologic hazards • Biologic • Fires • Other

  10. 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

  11. Major Disasters 1963-1992

  12. Disasters per 5-year Period

  13. Two Components of Risk Assessment • Trying to determine the likely impacts of a hazardous event. • 1. Physical aspects of hazards • Frequency, intensity, location • 2. Vulnerability • Exposed populations, structures, critical facilities, natural resources

  14. Why Assess Risk? • Provides estimates of: • Deaths and injuries • Property damage (our main concern) • Economic losses

  15. What can you do with this information? • Reduce risk through: • Mitigation • Preparedness • Warning strategies

  16. 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

  17. 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”

  18. 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

  19. Rapid Onset Hazards • Catastrophic events • Strike quickly but with devastating consequences • Large comet or meteorite impact • Also earthquakes, flash floods, sudden windstorms

  20. 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

  21. 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

  22. 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

  23. 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

  24. 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

  25. 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)

  26. 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

  27. 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

  28. 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?

  29. Vulnerability • Status of people and property in an area subject to hazards • Depends on type(s) of hazards as well as type of development

  30. 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

  31. 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

  32. 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

  33. 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)

  34. Hazard Assessment • Where • Magnitude • Frequency • Likely effects of occurrence • Provide information to planners and decision makers • Usually means a map or maps

  35. Landslide susceptibility map and recommended land use for Congress Springs area near San Francisco

  36. A Probability Map. Shows areas with highest probability of exceeding a certain magnitude of ground motion during an EQ

  37. Seismic risk map for USA shows expected damage for maximum EQ intensity. Map does not indicate frequency.

  38. 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

  39. 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

  40. 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

  41. 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

  42. 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

  43. 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

  44. Integrated system designed to reduce landslide hazards