Natural hazards
1 / 11

Natural Hazards - PowerPoint PPT Presentation

  • Updated On :

Natural Hazards. Chapter 4. Natural Hazard. What is a Natural hazard? Why should we study it? Natural events causing 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:

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about 'Natural Hazards' - lapis

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Natural hazards l.jpg

Natural Hazards

Chapter 4

Natural hazard l.jpg
Natural Hazard

  • What is a Natural hazard? Why should we study it?

    • Natural events causing 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

  • Damages from different types of Natural Hazards

  • Magnitude, frequency, catastrophe

    • Impact of a disaster is related to magnitude (how big) and frequency (how often). These two are inversely related. Actual damage depends on other factors too, such as population, climate, landuse, geology etc etc.

    • Catastrophe: immense damage: recovery and rehabilitation is a long invloved process

Benefits of natural hazards l.jpg
Benefits of Natural hazards

  • Flooding :

    • deposits fertile sediments in floodplains

    • Nourishes beaches

  • Volcano:

    • Adds landmass e.g., in Hawaii

    • Produces fertile soil

    • Created the atmosphere and hydrosphere

Evaluating hazards l.jpg
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 is magnifying damage

    • Consequences can be minimized

Disaster prediction l.jpg
Disaster Prediction

  • Location:

    • e.g., Volcanoes and earthquakes along plate boundaries

  • Probability of occurrence

    • Hazards are cyclical,

    • 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

Risk assesment l.jpg
Risk Assesment

  • 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

Human response to hazards l.jpg
Human Response to hazards

  • Reactive – traditional response

    • Impact

      • Direct (People killed, property damaged – affects individuals or small groups) and

      • Indirect effects (mental trauma, tax, donations—affects population)

    • 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

    • Disaster preparedness

  • Artificial control

    • Difficult, expensive and often cause more harm

      • Channelization of Kissimmee river

      • Sea walls, dams…

Future trends l.jpg
Future trends

  • Global Climate and hazard

    • Global warming is increasing weather related disasters

  • Population and hazard

    • Greater population density leads to higher risk

    • Change in land-use pattern magnifies damages

      • Recent floods in Haiti related to deforestation

Global climate and hazards l.jpg
. Global climate and hazards

  • A. Global and regional climate change may significantly affect incidence of storms, landslides, drought, fires

    • 1. how climate change may affect magnitude and frequency of natural events

      • a. sea level rise may increase coastal erosion

      • b. shift in food production areas

      • c. expansion of deserts and semi-deserts

    • 2. warming of oceans will channel more energy from ocean water into atmosphere

      • likely will increase hazardous weather-related processes

Population increase land use change and natural hazards l.jpg
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

      • a. more people at risk of an event

      • b. forces more people into hazardous areas

  • 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