2Hazards, Disasters, and Catastrophes Natural processes are physical, chemical, and biological changes that modify the landscape.Common denominators of vastly destructive natural events are transport of material (water, air, and earth) and expenditure of energy.
3EarthquakeEarthquakes result when the rocks that are under stress from the internal earth processes that produce our continents and ocean basins rupture.mostly at depths of 10 to 15 km along faultsEarthquakes release vast amounts of energy.they can release more energy than a large nuclear explosion.
5Volcanic EruptionVolcanoes are the result of extrusion at the surfaces of molten rock (magma).May be explosive and violent, or they may be less energetic lava flows.Generally occur at boundaries between tectonic platesSome volcanoes also occur in more central parts of tectonic plates where hot spots deep below heat the rocks.E.g. Yellowstone National Park and the Hawaiian Islands.
6LandslidesA general term for the down slope movement of soil and rock.Occur when the driving forces that tend to move materials down a slope exceed the resisting forces that hold the slope material in place.Resisting forces are produced by the strength of the material on slopes.The dominant driving force on slopes is the weight of slope materials influenced by the force of gravity. The steeper the slope and the heavier the slope materials, the greater the driving forces.
7LandslidesHuman processes that add to or increase the slope angle increase the drive forces.Resisting forces reduced by increasing the amount of water on or in a slope, or by removing vegetation that reduces the root strength of the soil or rock.
8HurricaneA hurricane is a tropical storm with circulating winds in excess of 120 km (74 mi)Move across warm ocean waters of the tropics.Hurricanes gather and release huge quantities of energyWater is transformed from liquid in the ocean to vapor in the storm
10TsunamiA series of large ocean waves produced after the ocean water is suddenly disturbed vertically by processes such asEarthquakes, volcanic eruptions, submarine landslides, or the impact of an asteroid or cometOver 80% of all tsunamis are produced by earthquakes.
11WildfireA rapid, self-sustaining, biochemical oxidation process that releases light, heat, carbon dioxide, and other gases and particulates into the atmosphere.Fuel is rapidly consumed during wildfireshelps maintain a balance between plant productivity and decomposition in ecosystems.The primary cause is vegetation built upWhen microbes are not able to decompose plants fast enough to balance the carbon cycle.
12Tornado A tornado is a funnel-shaped cloud of violently rotating wind Extends downward from large cells of thunderstorms to the surface of Earth.May occur when a cold air mass collides with a warmer one.Water vapor in the warmer part of the atmosphere is forced upward where it cools and produces precipitation.As more warm air is drawn in, the storm clouds grow higher and thunderstorm activity increases in intensity.Tornadoes concentrated in the Plains States
13Flood The inundation of an area by water. Produced by a variety of processes ranging fromIntense rainstorms to melting of snow, storm surge from a hurricane, tsunami, and rupture of flood protection structures, such as levees or dams.River floodingShapes the landscapes through erosion and deposition.Erosion has produced features as small as gullies and as large as the Grand Canyon of the Colorado River.
14Heat Wave A period of days or weeks of unusually hot weather A recurring weather phenomenon related to heating of the atmosphere and the moving of air masses.Hypothesized that human-induced global warming has increased the number and intensity of heat waves in recent years.Now considered the most deadly of all weather hazards
15Drought A period of months, or years, of unusually dry weather. Related to natural cycles of wet years that alternate with series of dry years.Thought to be related to the heating of ocean waters and the moving of major air masses.
17Hazards, Disasters, and Catastrophes These processes are naturalBecome hazards, disasters or catastrophes when people interact with or live and work where they occur.Natural hazardAny natural process that is a potential threat to human life and property.
18Hazards, Disasters, and Catastrophes A hazardous event that occurs over a limited time span in a defined geographic areaCatastropheA massive disaster that requires significant expenditure of money and time for recovery.
19Hazards, Disasters, and Catastrophes No area in the world is hazard freeAverage annual loss of life around 150,000Financial losses exceeding many billions of $$Hazards that produce extensive property damage are not necessarily the same ones that cause the greatest loss of life.Economic cost increasing because people moving to the coast.
21Taking a Historic Point of View Natural hazards are repetitive eventsTo evaluate the flooding of a particular river we can evaluate the history of flooding for that riverNeed to link the historic record with prehistoric records and modern measurements to gain greater insights into the flood hazard.
22Fundamental Concepts Related to Natural Hazards How natural processes and hazards, might be reduced, minimized or eliminated:Natural processes have service functions.Hazards are predictable.Linkages exist between hazards.Linkages exist between different hazards and between the physical and biological environment.
23Fundamental Concepts Related to Natural Hazards Hazards that previously produced mostly disasters are now producing catastrophes.Risk from hazards can be estimated.Adverse effects of hazards can be minimized.
24Natural Process Have Natural Service Functions Nature provides a number of natural service functionsClean air, water purification, mountain building, etc.Fault can produce springs and seepsHabitat for animals and plants
26Natural Process Have Natural Service Functions River and flatland adjacent to it form a floodplain.Many benefits for the environmentWater and nutrients are stored on the floodplain.Deposits on the floodplain contribute to the formation of nutrient-rich soils.Wetlands on the floodplain provide an important habitat for many birds, animals, plants, and other living things.The floodplain functions as a natural greenbelt that is distinctly different from adjacent environments and provides environmental diversity.
27Natural Process Have Natural Service Functions Volcanic eruption produce new landOver millions of years volcanoes produce the Hawaiian islands
30Natural Process Have Natural Service Functions Dust storms carry nutrient rich soilLandslides may form lakes.Physical processes linked to a varied landscapeW/o diversity in land diversity of life would be reduced.
31Hazards are Predictable Most hazards can be mappedWhere they have occurred in the pastMonitored for present day activityPredictabilitySpring snow melt and floodingEarthquakes often clusteredVolcanic eruption from dormant volcanoes usually preceded by precursor events
32Hazards are Predictable Statistic and probability useful in evaluating the frequency of a particular event.“100 year flood”Used to determine flood insurance and restrict developmentAnother important variable in predicting hazardous events is geographyForecasting events like tsunamis
35Linkages ExistUnderstanding the links between hazards and between the physical and biological environment is a important part of understanding the consequences of natural hazard.Hazards can be linkedVolcanic eruption-landslidesLandslides-floodingHurricanes-flooding-landslidesSubmarine earthquake-tsunamis
37Linkages exist Links to biological environment Global scale; comet-extinctionRegional scale; hurricane-beach erosion and vegetation destructionWildfires remove vegetation-landslidesErosion-loss of fish habitat
38Hazards that previously Produced Disasters are now Producing Catastrophes During the last 10,000 years human population grown exponentially>6.6 billion todayNow have 15 cities exceeding 10 million peopleMost in areas vulnerable to natural hazards
40Hazards that previously Produced Disasters are now Producing Catastrophes Nevado del Ruiz in ColombiaMudflow in 1845 killed 1,000 peopleMudflow in 1985 killed 21,000 peopleEvents predict and even mapped but warnings largely ignored
43Land Use Transformation and Natural Hazards Landscape transformationsFrom forest to agriculture or urbanMay turn a disaster into a catastropheE.g. flooding after deforestation along Yangtze River in ChinaE.g. landslides after Hurricane Mitch and deforestation in Honduras
44Risk from Hazards Can Be Estimated Risk is defined asThe product of the probability of that event occurring times the consequence should it occur.Determining consequence fairly straightforwardProperty damage, loss of lifeMore complicated is determining acceptable risk
45Risk from Hazards Can Be Estimated Acceptable riskThe risk that individuals or society are willing to takeE.g. millions of people choose to live in CA even though high probability of earthquakes
46Adverse Effects of Hazards can be Minimized Active vs. reactive responseResponse include search and rescue, firefighting and provision of emergency food, water and shelter following an event.
47Adverse Effects of Hazards can be Minimized Proactive choices1. land-use planning to limit construction in hazardous locations2. construction of hazard-resistant structures, such as floodwalls and levees3. protection of ecosystems on coastal floodplains and wetlands that provide natural protection from hazards4. well-thought-out plans for evacuation and relief following a disaster.
48Impact and Recovery from Disasters and Catastrophes Direct effectsPeople killed, injured, dislocated, made homeless or otherwise damaged by the event.Indirect event follow a disasterDonations, shelter, taxes to help finance recovery and emotional distress.May effect society as a whole
50Perceiving, Avoiding and Adjusting to Hazards People generally optimistic about natural disasters.Laws and regulations designed to control development in particular areas.Land-use planning is one of the best tools we have to avoid some hazards.Insurance may be required for flooding and earthquakesPeople often rebuild in the same spot
51Perceiving, Avoiding and Adjusting to Hazards EvacuationHurricanes can often be spotted days or weeks outDisaster preparedness also minimizes impact of hazardsRequires working chain of communicationControl of hazardsMany people have been led to believe they are protected by leveesE.g. Sacramento area
54What does the Future Hold with Respect to Disasters and Catastrophes? Every year we seem to set new global recordsEconomic losses from disasters and catastrophes# of disasters has increases significantly in the last ½ centuryIn part because of human population pressureUrbanization affects severities of eventsOceans getting warmer effects severity of storms
58What does the Future Hold with Respect to Disasters and Catastrophes? Anticipating hazards rather than simply reacting to them will help minimize economic losses and reduce pain and suffering.E.g. large earthquake in China