Understanding Natural Hazards and Minimizing Impact

1. Natural Hazard Impact Factors • Natural events can cause great loss of life or property damage: • 2004: Asian Tsunami: >200,000 • 1970: Bangladesh Cyclone: 300,000 • 1976: China earthquake: 300,000 • Different types of Natural Hazards: • Volcanism, earthquakes, Hurricane, tornado, Tsunami, Flooding, Landslides • Impact of a disaster is related to magnitude (how big) and frequency (how often). Actual damage depends on other factors too, such as population, land-use, local geology etc. • Catastrophe: immense damage: recovery and rehabilitation is a long process – New Orleans still not recovered after now 10 years

2. Damages from Natural Hazards in US

3. Evaluating Hazards • Fundamental Principles: • Hazards are repetitive and predictable • Risk Analysis is important for understanding impact • Hazards are linked, e.g., volcano, earthquake, tsunami, landslide, flooding, forest fire.. • Human interference can magnifying damage • Consequences can be minimized for some types of hazards but not others.

4. Disaster Prediction • Location: • e.g., Volcanoes and earthquakes along plate boundaries • Probability of occurrence • Hazards are statistical • With sufficient data probability of occurrence can be calculated • Precursor events • Volcanoes, earthquakes, landslide, flooding, often associated with precursor events • Forecasting • Is possible by monitoring hazards e.g., hurricanes, tsunamis, volcanic eruption etc • Warning • Should be issued even at the risk of the hazard not materializing. However, the public doesn’t understand this.

5. Risk Assessment • Risk Determination • Risk= probability X damage • Acceptable Risk • Risk-tolerance level of the society • Can vary: High for automobiles but low for nuclear accident • Problem and opportunities • Lack of long term data– how do we calculate risk? • Information may be complex and difficult to analyze e.g., what is the effect of radiation leak from a nuclear reactor? • Better risk assessment will lead to better decisions

6. Human Response to hazards • Reactive – traditional response • Stages: • Emergency: Search and Rescue, shelter, opening roads • Restoration: water and power, return to home, cleaning of rubble • Reconstruction I: Return to pre-disaster level • Reconstruction II: improvement • Rapid Restoration can be counter-productive • Anticipatory – a better way to reduce damage • Hazard perception by people and by government • Land-use planning: avoid hazardous locations • Insurance: often not extended to high risk areas • Evacuation plans and Disaster preparedness • Artificial control • Difficult, expensive and often cause more harm • Channelization of Kissimmee river • Sea walls, dams…

7. . Global climate and hazards • A. Global and regional climate change may significantly affect incidence of storms, landslides, drought, fires • a. sea level rise may increase coastal erosion • b. shift in food production areas • c. expansion of deserts and semi-deserts

8. Population increase, land-use change, and natural hazards • A. Population increase and hazardous events • 1. as population increases, need for planning to minimize losses from natural disasters also increases • B. Land-use change and hazardous events • 1. past half-century has seen dramatic increase in great catastrophes • 2. vast majority of natural disaster deaths between 1985-1995 were in developing world • a. Hurricane Mitch: hillsides stripped because of heavy rains on cleared and burned land • b. Yangtze River: timber harvest and conversion to agriculture has increased flood hazard