Chapter 2- Tectonic Hazards and Impacts

Define hazard

An event which has the potential to cause harm to the environment, people of the economy

Define natural hazard

An event caused by environmental processes and would occur without the presence of humans.

When does a hazard become a disaster?

When 10 or more people are killed

When 100 or more are affected.

How does the UN define a disaster?

“A serious disruption of the functioning of a community or society involving widespread human, material, economic or environmental losses”

Define vulnerability

How susceptible an area or population is to damage from a particular hazard or event.

What factors have an impact on the vulnerability of a place?

Level of development

Population density

Size of hazard

Preparation and planning

What is the purpose of the hazard risk equation?

What is the hazard risk equation?

To outline the interaction between a hazard, vulnerability and a country’s capacity to cope with hazards and disasters.

Risk = (hazard x vulnerability) / capacity to cope

Compare Nepal and New Zealand’s earthquakes in 2015 + 2016

Nepal- 2015, almost 9,000 people died

New Zealand- 2016, only 2 people died

Both were magnitude 7.8

Can be used to show variation in development and how this impacts on vulnerability

What are the factors that have an impact on the resilience of a country or area.

Building construction- are building codes enforced

Population density- more in an area, more affected, harder to evacuate

Level of urbanisation- higher concentration of people and buildings

Infrastructure- high or low quality

Wealth- ability to invest

Healthcare system- is it well staffed and equipped

Emergency services- are they well trained and equipped

Education- are people educated about the risks and actions to take, evacuation procedures etc

Level of corruption- does money go to the places intended

Accessibility/ isolation- how difficult it is to reach an area, harder to supply aid etc

Summarise a case study that relates the age of a population to vulnerability

Hurricane Katrina 2004

High percentage of victims were elderly

Lack of mobility when it comes to evacuation, need help from others

Older people less likely to leave their homes

What is the pressure release model and what purpose does it serve?

Demonstrates how there are a range of factors which increase vulnerability and why some areas lack resilience.

Model takes into account the socio- economic context of the hazard

Factors are split into three categories

Summarise why Haiti is a more vulnerable place? Why was it more vulnerable when the magnitude 7 (2010) earthquake hit?

Infrastructural weakness

Poor governance + corruption

Political unrest and instability

Inability to deal with the event

Consequences of colonialism and post- colonialism

Lack of development and significant poverty

Summarise the impacts that an earthquake had on a less developed country

Haiti, Caribbean 2010

Magnitude 7

220,000 died and millions affected

More impacts locally

Small scale economic impacts- destroyed livelihoods in primary sectors- fishing + agriculture

Summarise the impacts that an earthquake had on a more developed country

Tohoku, Japan 2011

Magnitude 9

100 foot high tsunami

28,000 died

Significant economic losses due to disruption to industries

What are the categories used in a pressure release model? + examples of factors that would fit in these categories

Root causes:

Limited access to- power, structure, resources

Ideologies- political + economic system

Dynamic pressures:

Lack of- local institutions + planning, training, appropriate skills, local investment, ethical standards

Macro forces- rapid urbanisation + population change, debt repayment, deforestation, soil degradation

Unsafe conditions:

Physical- dangerous location, low quality infrastructure, poor building quality

Socio-economic- special groups at risk, low income

Institutional- lack of public preparedness, endemic diseases

What does the pressure release model suggest about vulnerability being reduced.

Vulnerability can be reduces and resilience increased by addressing the following:

• Safety

• Reducing the pressures

• Addressing the root causes

• Hazard mitigation

• Management of funds

What is the most common way of measuring an earthquake?

By magnitude either on the Richter scale, the Moment Magnitude Scale or the Modified Mercalli Intensity Scale

Summarise the Richter scale

Typically ranked from 1 to 10 but has no upper limit

Logarithmic scale- magnitude 5 is ten times more powerful than a magnitude 4

Measured using a seismograph

Less accurate so scientists today generally use the Moment Magnitude Scale

Summarise the Moment Magnitude Scale (MMS)

Measures the energy released at the source/ focus

Measured using a seismograph

1 to 10

Logarithmic scale- magnitude 5 is ten times more powerful than a magnitude 4, energy released is 32 times greater

Summarise the Modified Mercalli Intensity Scale

Scale goes from I to XII

Ranks earthquakes based on intensity (the severity of ground shaking at a particular place based on the effects on humans, buildings and the environment) as opposed to magnitude (the amount of energy released)

Summarise the Volcanic Explosivity Index (VEI)

Logarithmic scale from 0 to 8

Used to measure the size of an eruption

Cannot be measured with scientific equipment

Calculated based on series of measurements + observations including:

• Height of material ejected into atmosphere

• Volume of material

• Duration of eruption

What do hazard profiles usually contain information about?

Magnitude

Speed of onset

Areal extent- how big of an area does it cover

Duration

Frequency

Spatial predictability- is there a pattern to where this happens

What are the pros of using hazard profiles?

Can be used to compare:

• Different hazards

• Same hazards with different processes e.g. a volcano at a destructive vs constructive boundary

• Same hazards with different human vulnerabilities e.g. developed or not developed country

What are the cons of hazard profiles?

Cons include:

• Other factors may have a greater influence on the impact

• Focus on physical factors when human factors may be the most important

• Multi-hazard events are not easily represented on a hazard profile

• They are subjective