Midterm #1-Chapter 1 Flashcards
What is a natural disaster?
Natural event in which large amount of energy released in short time, resulting in catastrophic consequences for life and infrastructure
- Usually caused by a sudden release of energy stored over a long time
- Usually not man-made but can result from ignorance of natural hazards
What are the 4 energy sources for disasters?
- Internal Energy-EQ, Tsunamis, Volcanos
- Gravity- mass movements, avalanches
- Solar Energy- meteorological storm, flood, drought, wildfire, magnetic storm
- Impact Energy
Where does Internal Energy come from?
- Radioactive Decay: derives from ongoing decay of radioactive elements (uranium, thorium, K)
-Residual heat from extraterrestrial impacts and heat left from early impacts on Earth
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What is gravity?
Attractive force between any two masses, directly proportional to the product of the masses and inversely proportional to the square of their separation
What does the potential energy of an object depend on?
The potential energy of an object depends on ELEVATION and is released as kinetic energy if the object falls
-“Matter poses gravitational potential energy proportional to its elevation”
The sun is a ____ ____ ___, combing 2 ____ nuclei to produce ______ releasing ____ ____ as ___ and ____=solar radiation
The sun is a nuclear fusion reactor, combing 2 hydrogen nuclei to produce helium releasing nuclear energy as heat and light=solar radiation
What is an example of Solar Energy Disaster?
- Tornadoes
- Flood and Avalanches: The entire hydrologic cycle is driven by solar heating, can lead to flood and avalanche
- Hurricanes- fuelled by solar energy that hits ocean surfaces
What is a Hazard?
Hazard: potential for dangerous event
What is vulnerability?
Likelihood a community will suffer when exposed to natural hazards
What is risk?
Risk=Vulnerability x Hazard
Ex: Seismic Risk
When do natural disasters occur?
Natural disasters occur when natural hazards intersect with vulnerable communities
- Hazards are beyond human control, but vulnerability can be controlled
What are the two big steps after a disaster?
- Response (short-term)
2. Recovery (mid-term)
What are the two big steps before a disaster?
- Mitigation (long-term)
2. Preparedness/Adaptation (long-term)
What is Response?
- Immediate actions after a disaster
- Includes emergency and medical workers, police firefighters
- Goal: “get situation under control”
What is Recovery?
Longer term actions to rebuild the community
- Goal: Get situation back to normal, pre-disaster state
What is Mitigation?
Advance activities to reduce risk
- Structural and non-structural
What is Structural Mitigation?
- Infrastructure: dams, dykes, floodways
- Retrofitting buildings
- EQ proofing home
What is non-structural mitigation?
- Land-use policies
- Severe weather warnings
- Building codes
- Public education
What is Preparedness?
Pro-active steps to plan for disasters and put in place resources needed to cope with them
-Ex: stockpiling goods, emergency kits, evacuation drills, first-aid training
What is the return period?
Return period: Average time between events
-ex: Damaging earthquake occurs on Van Island every 20 years approx
What is the formula for frequency of event occurrences?
Frequency=1/Period
- Gives you the average number of occurrences in a given time
Ex: Van Island experiences approx 20 years, 1/20=0.05 damaging earthquakes per year
What is magnitude?
Measure of amount of energy released
Magnitude is _____ proportional to ________
Magnitude is inversely proportional to frequency (large events occur less frequently than small)
What is the magnitude and frequency of a Great EQ? A very minor EQ?
Great Earthquake: Magnitude is 8 or higher, frequency is 1
Very Minor Earthquake: Magnitude is 2-2.9, frequnecy is 1,300,000
Frequency of weather-related disasters is _______. Frequency of geological disasters is _______.
Frequency of weather-related disasters is increasing. Frequency of geological disasters is stable.
Number of fatalities due to natural disasters is ______ worldwide and ______ in Canada.
Number of fatalities due to natural disasters is increasing slightly worldwide and decreasing in Canada.
Economic cost of natural disasters is ________ _____ due to _____ population and _____ infrastructure.
Economic cost of natural disasters is increasing rapidly due to increased population and vulnerable infrastructure.
How do natural disasters affect developed countries?
Developed countries typically have fewer casualties (better buildings, medical care, resources, education, lower pop.) and higher economic costs (extensive and expensive infrastructure)
Recent Canadian natural disasters are predominately ____-_____ due to long ___ ____
Recent Canadian natural disasters are predominately weather-related due to long repeat periods for geologic disasters
Earth’s internal structure can be considered in terms of what two components?
- Chemical Composition- what its made of
2. Rheology- how the material strains (deforms) under STRESS
What is stress?
Force per area, includes:
- Compression (pressure) perpendicular to surface, leads to contraction
- Tension: perpendicular to surface, leads to extension
- Shear: parallel to surface, leads to distortion
What is strain?
Relative deformation under stress
Rheology: What happens to liquids under stress?
Liquids flow under stress
Rheology: What happens to elastic solids under stress?
Elastic deformation is recoverable, the object will return to original shape when stress is removed
Rheology: What happens to ductile materials under stress? (ex: gold)
- Ductile deformation is permanent
Rheology: What happens to brittle materials under stress?
Brittle objects fracture
Rheology: What happens to plastic materials under stress?
Flows like a high-viscosity fluid (ex: glacier)
What is viscosity?
A material’s internal resistance to flow
What does rheology depend on?
Rheology depends on time (t), temperature (T), and pressure (p)
What leads to brittle rupture?
Abrupt stress, low temperature and/or low pressure can lead to brittle rupture
ex: Rock: brittle near earth’s surface will rupture during a EQ
What leads to plastic flow?
Long-term stress, high temperature and/or high pressure can lead to plastic flow
ex: Glaciers flow on long time scales but rupture on short
How is the earth organized in terms of chemical composition?
- Crust
- Mantle
- Outer Core
- Inner Core
How is the earth organized in terms of rheology?
- Atmosphere
- Hydrosphere
- Lithosphere
- Asthenosphere
- Mesosphere
- Outer Core
- Inner Core
Significance of Inner Core
- Composition: solid
- Temperature: 5000 C
- Density 14-16g/cm3
- 2% of Earth’s Mass
- Solid metal, mostly iron, some nickel
Significance of Outer Core
- Composition: Liquid
- Temperature: 4000 C
- Density: 9.7-14gcm3
- Fluid metal, iron and nickel
Significance of Mantle
Composition: lower mantle is plastic, upper mantle is brittle
- Temperature: 1000C-3000C
- Density: 3.5-5.7g/cm3
- 67% of Earth’s Mass
What is the Moho?
The Moho is the crust-mantle compositional boundary (Mohorovicic discontinuity)
Significance of Continental Crust
Composition: Brittle Temp: 0-1000C Density: 3.0g/cm3 0.1% of Earth's Mass Made up of basaltic (volcanic) rock, 48% silicia
Significance of Lithosphere
- Consists of the crust and upper-most mantle
- Rigid solids fused together form the lithosphere
Significance of Asthenosphere
- Soft plastic upper mantle
- Solid with partial melt, flows slowly under stress
Significance of Mesosphere
Stiff plastic layer below asthenosphere
What does solid/melted state depend on?
- Pressure
- Temperature
- Composition
