FS

1. Define/Explain what a disaster is + natural processes

A disaster is a sudden, substantial event that causes one or more of the following:

• Great physical damage

• Injury or loss of life

• A drastic environmental change

• Disasters can be caused by natural processes or man-made or even technological processes.

  • A natural process becomes a disaster when it seriously affects a vulnerable human community. Earthquakes, hurricanes, floods, and volcanic eruptions are normal Earth processes; the disaster results from their interaction with people, buildings, infrastructure, and society.

    Therefore, usually cannot prevent the natural process, but we can reduce the chance that it becomes a disaster through preparedness, stronger infrastructure, risk reduction, and resilience.

1. the common SI magnitude prefixes and their values.

1. Compare and contrast risk, perception of risk, hazard, and vulnerability.

• Risk is the probability that a hazard will occur and produce a loss.

  • Risk=Hazard×Vulnerability

  • A powerful hazard may produce little risk in an uninhabited area. A more moderate hazard may create high risk where many vulnerable people and structures are exposed.

• Risk perception is how dangerous a person believes something to be. It is subjective and may differ from statistical risk.

  • People may overestimate dramatic, unfamiliar, or uncontrollable hazards while underestimating familiar hazards.

  • For example, someone may be more afraid of a rare meteor strike than of regularly driving in dangerous weather.

• A hazard is an event or situation that has the potential to cause human or economic harm.

  Examples include:

  • Earthquakes and landslides

  • Floods and avalanches

  • Droughts and wildfires

  • Hurricanes and tornadoes

  • Biological hazards and diseases

• Vulnerability is a weakness that makes people, structures, or communities susceptible to harm.

  Examples:

  • Weak buildings in an earthquake zone

  • Homes constructed on a floodplain

  • Poverty or lack of evacuation transportation

  • Dependence on fragile electrical or communication systems

Explain what density is and how it relates to stratification.

Density is mass per unit volume (If particles are close together, the item has high density. If they are far apart, it has low density):

ρ=Vm​

Its common SI unit is:

kg/m3

In the presence of gravity, less-dense materials tend to rise or float above denser materials. When several materials separate into layers according to density, they become stratified.

Examples:

• Oil floats on water.

• Fresh water can float above denser salt water.

• Air lies above the ocean, while rock lies below it.

• Earth’s lower internal layers are generally denser than its upper layers.

• Ocean stratification is affected by temperature and salinity because both influence seawater density.

Density normally increases downward in a stable stratified system.

1. Explain why disaster scales are based on the Order-of-Magnitude concept and interpret graphs with logarithmic scales.

An order of magnitude means a factor or power of 10.

For example:

101=10,102=100,103=1,000

An increase of:

• 1 order of magnitude = 10×

• 2 orders of magnitude = 100×

• 3 orders of magnitude = 1,000×

• Natural-disaster measurements can range from extremely small to extremely large. —> On a regular linear graph, small values become crowded near the bottom while extremely large values may go off the graph. —> A logarithmic scale compresses this range and makes the pattern easier to see.

On a base-10 logarithmic axis, equal spacing may represent:

1, 10, 100, 1,000, 10,000

Therefore, do not interpret equal distances on a logarithmic axis as equal numerical increases.

For a simplified order-of-magnitude scale, an intensity-6 event compared with an intensity-4 event differs by:

106−4=102=100

So it is 100 times stronger under the course’s simplified assumption.

1. Relate natural-disaster risk and intensity to frequency, return period, and consequences (costs).

Intensity and frequency

There is generally an inverse relationship:

More-intense disasters occur less frequently.

Small earthquakes, storms, and floods happen relatively often. Extremely intense events are rarer.

Return period

The return period is the average number of years between events of approximately the same magnitude:

RP= number of events/number of years recorded​

• example:

  • If two Category 5 hurricanes occurred during 70 years:

    RP=270​=35 years

    This means one occurs every 35 years on average.

Consequences and costs

Disaster cost depends not only on physical intensity but also on exposure and vulnerability.

Consequences may include:

• Fatalities and injuries

• Property damage

• Loss of infrastructure

• Loss of social and economic functionality

A rare high-intensity event can have enormous consequences. but, frequent lower-intensity events may also produce large cumulative costs. Increasing population and property value can increase losses even if the physical hazard itself does not become stronger.

1. Explain how disasters are associated with the concentration or dilution of energy.

Natural-disaster energy may be concentrated in space or time.

Concentration in space

Energy initially spread over a wide area can become focused into a smaller region.

Example: Solar radiation heats large areas of ocean. Evaporation stores some of that energy as latent heat. Atmospheric circulation can then concentrate warm, humid air into a hurricane, where the energy appears as wind, rain, waves, and storm surge.

Concentration in time

Energy may accumulate slowly but be released rapidly.

Examples:

• Tectonic stress builds for years but may be released by an earthquake in minutes.

• Volcanic energy can accumulate for decades and be released over days.

• A landslide may develop over days but move in seconds.

• A meteor may travel for thousands of years before releasing energy in seconds.

Dilution

After release, energy spreads through a larger area and generally becomes less concentrated. However, diluted energy can still cause dangerous secondary events.

Examples:

• An earthquake transfers energy into a tsunami.

• A thunderstorm may produce flooding that lasts much longer than the storm itself.

• Volcanic energy may generate lahars or widespread ash effects.

The notes emphasize that natural disasters commonly require diffuse or slowly accumulated energy to become concentrated before its rapid release.

how do you get the disaster info you need from reliable sources.

Use sources that are:

• Produced by government scientific agencies, universities, or recognized scientific organizations

• Written or reviewed by qualified specialists

• Based on measurements, evidence, and clearly explained methods

• Recently updated when conditions are changing

• Consistent with several independent reliable sources

Useful source types include:

• Geological surveys for earthquakes, volcanoes, and landslides

• National weather agencies for storms and warnings

• Emergency-management agencies for evacuation instructions

• Peer-reviewed scientific articles for research findings

• Local authorities for immediate evacuation orders

Be cautious with:

• Unverified social-media posts

• Sources without an author or date

• Sensational headlines

• Maps or forecasts whose original source is unclear

For immediate danger, use official warnings rather than relying on informal posts.

1. List the 1st and 2nd most common elements in the Earth, ocean, and atmosphere.

Environment	Most abundant	Second most abundant
Earth’s crust	Oxygen, O	Silicon, Si
Earth’s core	Iron, Fe	Nickel, Ni
Ocean, by mass	Oxygen, O	Hydrogen, H
Atmosphere	Nitrogen, N	Oxygen, O

For the entire Earth by mass, iron is generally first and oxygen second. For most EOSC questions about surface rocks, “Earth” may refer to the crust, so read the wording carefully.

1. Define fluid, viscosity and compressibility and how they relate to the phases of matter.

A fluid is a material that can flow and change shape to fit its surroundings.

Both liquids and gases are fluids:

• Water is a liquid fluid.

• Air is a gaseous fluid.

Some solids can also flow over very long geological times. Glacial ice and deep, hot rock are examples.

Viscosity measures a fluid’s resistance to flowing or changing shape.

• High viscosity: flows slowly and requires more force to move, such as thick magma

• Medium viscosity: water

• Low viscosity: air

Viscosity depends on temperature and chemical composition.

• Compressibility is the ability of a material to be squeezed or expanded so that the same mass occupies a different volume.

  • Compression changes density because:

    • ρ=m/V​

If volume decreases while mass remains constant, density increases.

Relationship to phases

Phase	Fluidity	Compressibility
Solid	Not very fluid	Not very compressible
Liquid	Very fluid	Not very compressible
Gas	Very fluid	Very compressible

These properties help explain how air, water, magma, and rock respond during natural disasters.

Be able to diagnose the type of strain by the way a material deforms.

Strain is a change in an object’s shape or size caused by stress.

Elastic strain

The material deforms while stress is applied but returns to its original shape when stress is removed.

Examples:

• Spring

• Rubber band

• Rock under relatively small stress

Plastic strain

The material deforms and remains permanently changed after the stress is removed.

Examples:

• Bent soft metal

• Flowing glacial ice

• Deep rock deforming over geological time

Fracture or brittle behaviour

The material does not deform much before breaking.

Examples:

• Ceramic plate

• Brittle rock breaking along a fault

Stress–strain sequence

Many materials respond in this order:

1. Elastic deformation

2. Yield point

3. Plastic deformation

4. Fracture

A material that bends or deforms easily is ductile. A material that breaks instead of bending is brittle.

1. Explain why gravity affects motion and energy.

Gravity is a force of attraction between masses. Near Earth’s surface:

F=mg

where:

• m = mass

• g = gravitational acceleration, approximately 9.8 m/s^2

Gravity accelerates unsupported objects downward, producing motion and increasing their kinetic energy.

Gravity also produces gravitational potential energy:

PE=mgz

where z is height.

An object higher above the ground has more potential energy. When it falls, potential energy is converted into kinetic energy.

Natural-disaster examples:

• Rocks falling in a landslide

• Water flowing downhill during a flood

• Volcanic material descending during a lahar

• Snow moving downhill in an avalanche

1. List the 5 types of energy, and describe what causes them to vary.

1. Work

Work occurs when a force moves an object through a distance:

W=Fd

Work increases with greater force or greater distance in the direction of the force.

2. Potential energy

PE=mgz

Potential energy increases with:

• Mass

• Gravitational acceleration

• Height

3. Kinetic energy

KE=(1/2)​mv2

Kinetic energy increases with:

• Mass

• The square of velocity

Because velocity is squared, doubling speed produces four times the kinetic energy.

4. Sensible heat

Sensible heat is energy that changes a material’s temperature:

ΔQH​=mcΔT

It varies with:

• Mass

• Specific heat capacity

• Temperature change

5. Latent heat

Latent heat is energy stored or released during a phase change:

ΔQE​=LΔm

It varies with:

• Mass changing phase

• The material’s latent-heat constant

Energy is stored during melting and evaporation. It is released during freezing and condensation.

All five are measured in joules.

1. Explain (with examples) how energy conservation applies to natural disasters.

The law of energy conservation states:

Energy is neither created nor destroyed; it changes from one form to another.

Examples:

Meteor impact

The meteor’s kinetic energy becomes:

• Sensible heat

• Latent heat from melting or vaporization

• Ground motion

• Sound

• Work involved in forming a crater and ejecting material

Volcano

Heat below Earth’s surface:

• Evaporates water and stores latent heat

• Produces expanding vapour

• Does work on magma

• Raises magma, increasing its potential energy

• Produces kinetic energy during eruption

Landslide or lahar

Rock or water high on a slope has potential energy. As it moves downhill:

PE→KE

Some energy also becomes heat, sound, deformation, and work done damaging structures.

Hurricane

Solar energy heats the ocean. Evaporation stores latent heat in water vapour. Condensation releases that heat, helping drive atmospheric motion:

solar/heat energy→latent heat→kinetic energy

Energy changes form throughout the disaster, but the total amount is conserved.

1. Describe relationships between force, pressure, stress, strain, energy, and power.

Force

A push or pull that can accelerate or deform matter:

F=ma

Unit: newton, N.

Pressure

Force per unit area acting perpendicular to a surface:

P=F/A​

Stress

Force per unit area acting parallel to a surface in the course notes:

τ=F/A​

Stress can deform material and cause strain.

Strain

The deformation caused by stress. It may be elastic, plastic, or end in fracture.

Energy and work

If a force moves matter through a distance, it does work and transfers energy:

W=Fd

Power

Power is the rate at which work is done or energy is transferred:

Power = Energy/Time​

Unit:

1 watt=1 joule/second

Full relationship

Force over area→pressure or stress Stress→strain or fracture Force through distance→work and energy transfer Energy transferred rapidly→high power

Disasters are especially destructive when large amounts of energy are transferred over a short time, producing high power.

1. Describe population growth and explain why it is important for natural disasters.

Human population has experienced exponential growth, meaning growth becomes faster because each larger generation adds more people.

Exponential growth resembles compound interest: growth is added to an increasingly large base.

Doubling time

For an exponentially growing population, approximate doubling time is:

DT≈ 70​/ annual growth rate in percent

At 1% annual growth:

DT≈70 years

At 2% annual growth:

DT≈35 years

Why population growth matters for disasters

As population grows:

• More people live in hazardous areas.

• Settlements expand onto steep slopes, floodplains, coasts, and fire-prone areas.

• More buildings and property are exposed.

• Evacuation becomes more difficult.

• Infrastructure becomes more interconnected and sensitive.

• Failure of electricity, water, transportation, communication, or health systems affects more people.

• Recovery becomes more expensive.

Therefore, the same physical event can become a much larger disaster as exposure and vulnerability increase.

1. Explain how Earth's carrying capacity and overpopulation are related to the fate of the human race, and anticipate your role in it.

Earth’s carrying capacity is the maximum population that can be sustainably supported given the continued availability of:

• Food

• Water and clean air

• Energy and other natural resources

• Living space

• Sanitation

• Medical care

• Functioning ecosystems and infrastructure

A population above the carrying capacity is overpopulated.

As carrying capacity is approached, shortages and competition may increase, while quality of life and resilience decline.

overpopulation can make infrastructure more fragile, evacuation less successful, disaster losses greater, and human society more vulnerable to long-lasting disruptions.

The course’s overall conclusion is that earthquakes, volcanoes, hurricanes, floods, and similar processes are not disasters to Earth. They are normal parts of Earth’s evolution. The danger is primarily to an increasingly concentrated, dependent, and vulnerable human population.

Your role includes:

• Learning and communicating accurate hazard information

• Preparing yourself and your community

• Supporting resilient infrastructure and sensible land-use planning

• Reducing unnecessary resource consumption and waste

• Supporting access to education, health care, and voluntary family planning

• Considering sustainability in personal, professional, and political decisions

The goal is not merely survival but a sustainable society that is resilient to natural hazards.