# Our Hazardous Environment GEOG 1110 Dr. Thieme - PowerPoint PPT Presentation

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Our Hazardous Environment GEOG 1110 Dr. Thieme. Scientific Method, Forecasts, Prediction, and Risk Assessment. Scientific Method. make observations. formulate a hypothesis. test the hypothesis with new observations. draw conclusions (build a "theory"). Scientific Hypothesis.

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Our Hazardous Environment GEOG 1110 Dr. Thieme

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## Our Hazardous EnvironmentGEOG 1110Dr. Thieme

Scientific Method, Forecasts, Prediction, and Risk Assessment

### Scientific Method

• make observations

• formulate a hypothesis

• test the hypothesis with new observations

• draw conclusions (build a "theory")

### Scientific Hypothesis

• a tentative assumption that is made for the purpose of a study.

• testable against data obtained by experiment or from field observation

• disproving your hypothesis thereby confirms its opposite ornull hypothesis

• Observation: A landslide occurred and destroyed three homes

• Hypothesis:Water on the hillslope, seeping from a buried waterline, caused the landslide

### Risk Assessment

• using statistical methods to quantify the risks involved in a particular action

• risks are compared and contrasted before deciding how to act

• risks are evaluated in order to identify the causes of a medical condition or an environmental problem

### Risk

• probability calculated as a fraction:

• 0 (certain not to occur)

• 1 (certain to occur)

• multiplied by the consequences

• consequences can be harm or loss to:

• people

• property

• economic activity

• public service....

### Risk Analysis

• estimate the probability that an event will occur and the consequences resulting

• Los Angeles has a 5 percent chance of a moderate earthquake (p = 0.05)

### Risk Analysis

• large events have lower probability than small ones

• but consequences tend to be greater

Acceptable Risk - the risk that society or individuals are willing to take

• businesses calculate risk in economic terms

• individuals also incur risk

### Risk Analysis and Planning

• delineate areas where hazards occur

• identify the processes responsible

• attempt to control nature ("flood control")?

• provide maps and information to planners and decision maker in order to

• avoid putting people and property in harm's way

### Avoiding Disasters

• Land Use Changes: Avoid building on

• floodplains

• areas where there are active landslides

• places where coastal erosion will occur

• Insurance (flood, earthquake, etc...)

• Evacuation

• Preparedness - Train individuals and institutions to handle large numbers of injured and limit mass hysteria

Flow Path for Predicting or Warning about a Natural Disaster

### Prediction and Forecast

• Prediction involves specifying date, time, and size of an event (flood resulting from tropical storm, etc...)

• Forecast is a prediction with a range of certainty (and uncertainty!)

• For some types of natural hazard, neither prediction nor forecast is really possible

• Some assessment of risk is always possible

### Precursor Events

• linked with a hazardous event either causally or statistically

• Foreshocks or unusual uplift of land may precede earthquakes

• Volcanoes sometimes swell or bulge before they erupt

• Sea may withdraw suddenly from a beach before a tsunami hits

### Natural Hazard Impacts

• Magnitude of an impact

• Frequency of impacts

• Magnitude and Frequency are inversely related

• Large magnitude events occur less frequently

• Large magnitude events have a lower probability of recurring in any given time interval

### The "Golden Mean"

• Most of the work of forming Earth's surface is done by events of moderate magnitude and frequency

• "Bankfull" Floods

• Normal Wave Base in Nearshore Zone

• Mid-latitude Cyclone Storms

### Natural Hazard Impacts

Direct Effects include people killed, injured, dislocated, or otherwise damaged

Indirect Effects include

• emotional distress

• donations of money and goods

• financial disruption and funding of recovery

### Disaster Recovery

Stages of Disaster Recovery:

• Emergency Work

• Restoration of Services and Communication Lines

• Reconstruction

### Human Dimension

• Human Interaction with Natural Hazards increases with population density

• Some technologies play a specific role in triggering or mitigating disasters and catastrophes caused by natural hazards

• Human Interaction with Natural Hazards is discussed in each chapter of your textbook (Sections 2.8, 3.6, 4.6, etc...)

• Risk Assessment is important to understanding the effects of natural hazards

• Minimizing the Risk from Natural Hazards is discussed in each chapter of your textbook (Sections 3.9, 4.6, 5.7, etc...)

• Earthquakes produce

• landslides

• tsunamis

• Hurricanes cause

• flooding

• coastal erosion

• Volcanic eruptions cause

• lahars (catastrophic floods laden with ashy mud)

• weather and even climate changes downwind

• Hurricanes (Katrina)

• high winds damage property and harm people directly

• flooding that follows storm does more damage, for which landowners may not be insured

• coastal flooding is linked to other coastal processes

• tropical storm intensity may increase in warmer climate due to sea surface temperatures

• Earthquakes (Pakistan) and Volcanoes (Nevado del Ruiz)

• represent plate tectonic movements and in turn trigger landslides, floods, tsunamis,....

### Natural Service Functions

• "Ecosystem" services are benefits to humankind which result from resources and processes supplied by natural ecosystems:

• provisioning such as production of food and water

• regulatingsuch as control of climate and disease

• supporting such as nutrient cycles and crop pollination

• cultural such as spiritual and recreational benefits

• preserving such as maintenance of biodiversity

• Natural Service Functions of Natural Hazards are discussed in each chapter of your textbook (Sections 2.7, 3.5, 4.5, etc...)