Option D: Geophysical hazards (earthquakes)

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Volcanoes are convergent boundaries so it is often that

earthquakes occur near them- sometimes in isolation in the ocean

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Earthquakes are caused due to the

friction caused during subduction

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A landslide can cause

large floods and tsunamis when they hit rivers or other large water bodies

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Adaptations are ways in which human activities are

altered to take into account the increasing risk of hazards

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Disasters are

major hazard events that impact a drastic amount of persons, creating many casualties (BIG HAZARD)

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Hazard events are

occurrences of hazards that change demographic, economic and/or environmental conditions

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Risk is the probability of a hazard event causing

harmful consequences, deaths, injuries, property damage economy and environment

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Hazard perception is the degree to which

a hazard is considered to be. threat by different people

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Resilience is the ability to protect

lives, livelihoods, and infrastructure from destruction, and to the ability to recover after a hazard

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Risk of disaster [R] is measured by

(Severity of hazards [H] x People vulnerability [V])/ Capacity to cope [C]

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Plate margins are

zones at which the most magma is produced

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Ground technology is used to measure

gas emissions, grounds of formation, and resulting earthquake activity

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Technology, monitoring, and evidence from past eruptions are used to model and create

eruption scenarios, hazard maps, and eruption timelines

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As scientists can’t always get their predictions right, governments often

refuse to listen, as preparations and monitoring require large funds

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The pressure release model measures risk by considering

the progression of vulnerability (root causes, dynamic pressures, unsafe conditions) and natural hazards

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Root causes include

limited access to power, structures, resources, and political and economic ideologies

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Dynamic pressures include

a lack of training, local investment, press freedom, with rapid population change, rapid urbanization, and deforestation

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Unsafe conditions include

physical environmental, local economy, social relations and public action pressures.

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Natural hazards include

earthquakes, flooding, landslides, volcanic eruptions, droughts, virus and pests, and wind storms

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Earthquakes occur along plate boundaries, especially

convergent ones forming from subduction.

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Friction is created through the opposing

forces in the two plates during subduction

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Friction created through boundaries sends

seismic shock waves and vibrations that make up an earthquake

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The stronger and shallower the earthquake is

the more violent its destruction

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Earthquakes under oceans create

big, destructive waves called tsunamis

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Around 100 out of 500,000 earthquakes per year

cause damage

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The Moment magnitude scale is preferred to the Richter scale due to its

lack of upper limit

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Both the moment magnitude scale and the richter scale

increase in magnitude 10x for every whole number increase in value

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Using historical earthquake data, governments and scientists are trying to

predict when and where the next earthquakes will occur

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Engineers are investing in building infrastructure with

lighter roofs, flexible structures and stronger foundations to deal with earthquakes

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Countries with good earthquake-proof infrastructure include

Taiwan and Japan

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The valdivia earthquake in Chile was

the largest earthquake ever recorded with a magnitude of 9.5, lasting 10 minutes.

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The valdivia earthquake in Chile created

a tsunami which reached as far as Japan, affecting the globe

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Risk that comes with an earthquake include

building codes not being up to date and poor governance and city planning restricting access to essential aid

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Hospitals and services built on the edges of towns are examples

of essential services being build quickly on the cheapest land and being inaccessible in times of disaster

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Roads collapsing

obstructs people’s access to essential resources + facilities

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It’s not earthquakes that cause casualties,

it’s poor buildings

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Stress

force per unit area acting on a plane within a body

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Tensional stress

Builds in faults on divergent plant boundaries

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Compressional stress

Builds up in faults on convergent plate boundaries

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Sheer stress

Builds up in faults on plate boundaries moving side by side

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Seismic waves

transfer energy in all directions

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P-waves are the

deepest in the ground and produce the smallest waves in a seismograph

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S-waves are the

precursor waves we feel, a little larger than P-waves on seismographs

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Surface waves are

the largest waves seismographs and are the waves creating the impactful waves

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Surface waves include

Love and Raleigh waves

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Releigh waves move

in circular motions (like jump ropes)

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Love waves move

in sideways motions (like s-waves on their sides)

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S-waves move

in wave motions

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P-waves move in

compressional motions

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Earthquakes root from a focus which is

a point along the fault line where pressure builds and releases

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The point directly above the focus, on the surface is the

epicenter, where energy on the surface will be the greatest (as the point of origin)

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Wave fronts in the crust become

seismic waves on the surface

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The fault line is

the line along which two plates slide against each other violently in opposing directions

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Liquefaction is

a primary hazard of earthquakes where the ground turns to liquid

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Shaking, cracking and opening of the ground are

primary hazards of earthquake events

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Small, triggered fires and landslides are

secondary hazards of earthquake events

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Mercalli scale is

based on observable earthquake damages and the effects at a given location on a scale of 1 to 12 (equal to 1 to 8 on Richter)

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Richer scale is

calculated from the earthquake’s largest seismic wave amplitude and considered movement on a scale of 1 to 10 (each 10 times more intense than the last)

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Mercalli scale’s benefits include

Intensity being directly linked to the physical effects felt making it more tangible and accessible for more people

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Richter’s scale’s benefits include

Quantifiable, scientific and hence, accurate measures of earthquake strengths that allow for standardized comparisons of earthquakes

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Mercalli scale’s limitations include

it is subjective and harder to compare and can use descriptions not everyone has experience with based on their environments.

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Richter scale’s limitations include

it doesn’t reflect vertical movement and is valid for certain frequencies and distances only. It is also every inaccessible to people without prior knowledge

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The moment magnitude scale

considers distortion and displacement of the ground along with the amplitude measurements of the Richter scale to create a more accurate measurement

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The moment magnitude scale increase

32 times in energy released with every additional magnitude

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Creeping zones

earthquake zones where slow and steady movements occur allowing for energy released slowly

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Slip zone

earthquake zones where there is build up of stress and it is released violently

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Understanding the frequency of earthquake occurances

can help model future fault slips and inform governments of time frames within which an earthquake is expected so they can plan around and mitigate its effects

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Information needed for earthquake risk management include

Population density, access and roads to health services, urban landscapes and construction

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As magnitudes of earthquakes increase

the frequency of their occurrences decrease

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In general, earthquakes occur

more frequently than volcanos as there are more fault lines than hot spots

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Technological advancements can play a huge role in increasing reported earthquakes as

more small earthquakes are being recorded, giving the media the illusion of their increased frequency

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Why might people choose to live in areas affected by earthquakes?

Lacking socio-economic means, indigenous/emotional connections to land, low risk perception hence people live unaware of the hazard or able to mitigate it or because of present earthquake proofed infastructure

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How can planning reduce the effects of an earthquake?

People could be evacuated, buildings could be proofed and checked for stability, land use could be further developed to reduce urban risk, education to respond to earthquakes could prevent increase casualties as well as readily available health services being prepared

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Earthquake predictions are based on

Date and time, location and magnitude

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Suggested precursors to earthquakes include

radon in local water, unusual behavior in animals, increasing magnitudes of events to suggest foreshock

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A real earthquake prediction is

made on scientific basis in probabilistic terms

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Economic reasons to live near earthquake zones

An Earthquake pushes the land further up, thus helping vegetation flourish as it allows nutrients and minerals to be deposited evenly, creating a very fertile soil. There are many minerals in tectonically active zones

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Cultural reasons to live near earthquake zones

Ancestral lands or inherited ways of living, interpretation of earthquakes as mother nature’s response

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Social reasons to live near earthquake zones

People may not be as well educated hence they might be unaware of the risks, it can be close to family, or just a simple way of living

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DROP, COVER, HOLD is a

public earthquake response strategy aimed to protect people and their vital organs from overhead debris

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DROP, COVER, HOLD advantages

Catchy and easy to remember even with language barriers, applicable despite income or social class, inexpensive strategy

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DROP, COVER, HOLD disadvantages

Needs sturdy structure to hide under for debris inflection- might not be so available in lower income areas and they don’t mitigating risk for disabled persons as still exposed to debris 

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DROP, COVER, HOLD is used in

USA for the Great ShakeOut and globally as a first, applicable measure across all levels of development 

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The US Great Shake-out is

an earthquake preparedness drill that occurs across the entire country and has around millions of participates

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The US Great Shake-out advantages include

all societal units (businesses, families, etc.) to practice together for greater cohesion in real scenario, reaches a wide range of people and educates them, people are incentivized to plan for it and practice it, and people can properly check up on emergency supplies, etc.

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The US Great Shake-out disadvantages include

disrupting daily lives the more it is practiced nationwide, requires great organization and cohesion throughout the country and its timezones

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Earthquake preparedness infrastructure includes

structural mitigation measures, non-structural mitigation measures, contents mitigation, and design modifications

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Structural mitigation measures are

the strengthening of building elements (foundations, columns, load-bearing walls, floor/roof diaphragms) to resist seismic and lateral forces.

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Non-structural mitigation measures are

the improvements of seismic resistance of components like parapets, chimneys, HVAC systems, and windows through bracing or anchoring.

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Contents mitigation is

Securing heavy items (bookcases, file cabinets, electronics) to prevent injuries if they fall during hazards (e.g., tsunamis, floods, major hazmat sites). 

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Design medications are

the encouragement for appropriate building designs in vulnerable areas; discourage high-rise structures and large industrial facilities in these regions. 

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Earthquake ready kits are

bags of emergency foods, water, flashlights, protective pieces and first aid kits in the case of earthquakes with limited support

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Earthquake ready kits

help mitigate earthquake hazards as people are prepared to access basic needs for long periods of time 

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Earthquake ready kit disadvantages are

incur personal costs- not available to all- Materials can expire before they are used

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Earthquake ready kits are used in

Japan to deal with their frequent earthquakes

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Liquefaction is the increased pore water pressure in soil causing water gaps between soil pores to increase in size which

liquefies the ground and decreases its load bearing capacity as friction in the top soil is overcome and soil forms heavy clumps and sinks to the bottom and water lifts up

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What causes Liquefaction?

Heavy construction activities, earthquakes or volcanoes that cause intense shaking

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Liquefaction ground deformation types include

Lateral spreading, ground oscillations, and settlement

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Lateral spreading is

the horizontal displacement of ground after liquefaction as liquid soil flows towards divots in the land

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Ground oscillations are

a back and forth movement of liquid soil that is triggered by further shaking, increasing the destabilization of infrastructure