Tectonics

Hazard

Hazard

A potential threat to human life and property.

Hydro-meteorological hazard

A natural hazard caused by climatic processes.

Geophysical hazard

A natural hazard caused by land processes.

Plate boundaries

The areas where tectonic plates meet.

Intra-plate earthquake

An earthquake that occurs within the middle of a tectonic plate.

Volcanic hotspot

A localized area of the Earth's crust and upper mantle with an unusually high temperature, resulting in volcanic activity.

Lithosphere

The Earth's crust and upper mantle.

Convergent boundary

A plate boundary where two plates move towards each other. (powerful eq)

Conservative boundary

A plate boundary where two plates slide past each other. (powerful eq)

Destructive boundary

A plate boundary where one plate subducts beneath another.

Constructive boundary

A plate boundary where two plates move away from each other.

OFZ

Oceanic Fracture zone: a belt of activity through the oceans and along the mid-ocean ridges through Africa, the Red Sea, the Dead Sea

CFZ

Continental Fracture Zone: a belt of activity along the mountain ranges from Spain through the Alps to the Middle East and to the Himalayas

Paleomagnetism

The study of rocks that show the magnetic fields of the Earth.

Seafloor spreading

The process by which new oceanic crust is formed at mid-ocean ridges and spreads apart.

Rift valley

A valley formed by the separation of continental plates.

Horst

The lifted areas of rocks formed during continental to continental plate separation.

Graben

The valley formed during continental to continental plate separation.

Conservative plate boundary

A type of plate boundary where parallel plates move in different directions or at different speeds, without any destruction of plates or creation of landforms.

Oceanic crust

The type of crust that is low in density, mainly composed of basalt, thin, and newly created.

Continental crust

The type of crust that is high in density, mainly composed of granite, thick, and old.

Mantle convection

The mechanism of plate movement caused by the heating and rising of the lower mantle due to thermal energy produced by the decay of radioactive elements in the Earth's core.

Slab pull

The mechanism of plate movement where old oceanic crust, which is the most dense plate, submerges into the mantle and drags the rest of the plate with it.

Ridge Push

Slope created when plates move apart has gravity acting upon it as it is at a higher elevation. Gravity pushes plates further away, widening the gap (movement influenced by gravity, known as gravitational sliding).

Earthquakes

Sudden movements of plates caused by the release of pressure built up between stuck plates, resulting in seismic waves spreading throughout the ground.

Tectonic Trends since 1960

Despite a decrease in fatalities, mega-disasters still lead to spikes in casualties.

Tectonic hazards continue to affect more people as the population grows.

The economic costs of disasters have risen due to infrastructure development in wealthier countries.

Additionally, more insurance policies in these countries contribute to higher costs.

Why is reporting disaster impacts (e.g. fatalities) very difficult and controversial?

If you look at direct vs indirect deaths. (some impacts take time to show)

The location (e.g rural/isolated or high population density)

Different methods are used by diff organisations = diff num.

Numbers of deaths quoted by gov may be biased (e.g 2004 Indian Ocean Tsunami, Burmese gov - 0 deaths inn Burma - show gov good job at aid/protection etc)

Focus

The point underground where an earthquake originates from.

Epicentre

The area above ground directly above the focus of an earthquake.

Seismic waves

Waves produced by earthquakes, including:

• primary waves (compressional, through solids),

• secondary waves (vibrates at right angles to the direction of travel, only through solid rocks)

• Love waves (near ground surface, rolling motion producing vertical ground movement)

• Rayleigh waves (vertical + horizontal displacement).

Aftershocks

Different types of seismic waves arriving after an earthquake, causing secondary jolts or tremors.

Soil liquefaction (secondary hazard)

Poorly compacted sand and silt behave like a liquid due to the separation of water moisture from soil particles, causing building subsidence or landslides.

Landslides (secondary hazard)

Shaking weakens or damages cliff faces, hills, and loose rocks, causing collapses and the potential for material accumulation.

Tsunamis (secondary hazard)

Large ocean waves generated by the displacement of water during an eq.

Gravity = water pulled down, energy travels through it as a wave. Waves travel quickly but with low amplitude. Approach the coast, friction between the sea bed/waves = slow down + gain height = wall of water up to 100ft high.

Subduction zones

Areas at convergent plate margins where one plate is forced beneath another, often associated with the generation of tsunamis.

Volcanoes

Openings in the Earth's crust where molten rock, ash, and gases are ejected onto the surface.

Lava flows

Streams of molten rock that have erupted onto the Earth's surface, with the speed and danger depending on the lava's viscosity.

Pyroclastic flows

Mixtures of hot dense rock, lava, ash, and gases that move quickly along the surface of the Earth, posing extreme danger.

Tephra and ash flows

Pieces of volcanic rock and ash blasted into the air during an eruption, causing damage to buildings and potential collapse.

Volcanic gases

Gases released into the atmosphere during volcanic eruptions, such as sulfur dioxide and carbon monoxide, which can travel long distances.

Lahars (secondary)

Combination of rock, mud, and water that travel quickly down the sides of volcanoes, often caused by the melting of snow and ice due to volcanic heat or heavy rainfall.

Jokulhlaup (secondary)

Sudden floods caused by the melting of snow and ice in glaciers after a volcanic eruption.

Acid rain (secondary)

Rainfall that is acidic due to the release of gases like sulfur dioxide into the atmosphere during volcanic eruptions.

Disaster

A serious disruption of the functioning of a community or society involving human, material, economic, and environmental losses which exceeds the ability of the affected community or society to cope using its own resources.

Resilience

The ability of a population to cope with and recover from a hazard.

Vulnerability

The susceptibility of a population to the negative impacts of a hazard.

Hazard

A natural event or phenomenon that has the potential to cause harm or damage to human life, property, or the environment.

How is Risk calculated?

Risk = Hazard x Vulnerability /Capacity to cope

Development affects this.

High risk if: capacity to cope is low, quite vulnerable and the hazard is large/ high intensity.

Degg's Model

A model that represents the concept that a disaster will only occur when a vulnerable population is exposed to a hazard.

United Nations Office for Disaster Risk Reduction (UNISDR)

An organization that defines a disaster as "a serious disruption of the functioning of a community or society involving widespread losses and impacts, which exceeds the ability of the affected community or society to cope with using its own resources."

How else can you classify a tectonic hazard?

1. Volume of ppl affected: International Disaster Database classifies a disaster as an event where more than 100 people are affected or more than 10 people die.

2. Economic cost: financial impact, including jobs lost, cost of repairs, and econ productivity lost.

3. Comparing to previous events or models.

Park Model

A graphical representation of human responses to hazards, showing the steps carried out in the recovery after a hazard.

Steepness of the curve = how quickly an area deteriorates and recovers.

Depth = scale of the disaster i.e. lower curve, lower quality of life

What are the stages of the Park model?

1. Relief: immediate local response to a hazard, e.g medical aid + search and rescue.

2. Rehabilitation: services begin to be restored, temporary shelters/hospitals set up, food and water distributed.

3. Reconstruction: area is restored to same or better quality of life, infrastructure rebuilt, mitigation efforts for future events are implemented.

Pressure and Release Model (PAR)

A model used to analyze factors that cause a population to be vulnerable to a hazard.

1 side of the model = natural hazard + other side different factors and processes which increase a population’s vulnerability to the hazard - often rooted in social processes = dynamic, changing, often unrelated to the hazard e.g. poverty, poor governance

Physical Vulnerability

Individuals living in a hazard-prone area with little natural protection or mitigation.

Economic Vulnerability

People at risk of losing employment, wealth, or assets during a hazard.

Social Vulnerability

Communities unable to support their disadvantaged or most vulnerable members, leaving them at risk to hazards.

Knowledge Vulnerability

Individuals lacking training or warning to know the risks of a hazard or how to safely evacuate.

Environmental Vulnerability

A community's risk to a hazard is increased due to high population density in the area.

Root causes of vulnerability

1. Weak governance gov unable to effectively plan and control safe population growth or provide necessary infrastructure.

2. Mismanagement by Industry, NGOs or IGOs.

3. High reliance on products easily affected by hazards (e.g nearby agriculture, imports).

Unsafe Living Conditions which cause vulnerability.

Factors such as lack of infrastructure, dangerous location of settlements, and absence of warning systems.

Dynamic pressures that cause vulnerability.

1. lack of training/knowledge in locals.

2. rapid urbanisation

3. poor communication between government and locals

4. natural environment degraded (mangroves removed, rivers & channels filled with debris)

5. lack of basic services (health, education, police)

Hazard Profiles

Comparing the physical characteristics of hazards to aid decision making

Characteristics of a hazard profile

• Frequency: how often a hazard occurs

• Magnitude: Extent of area affected by an event

• Duration: Length of time a hazard lasts

• Speed of onset: Amount of warning time before the hazard.

• Fatalities: Number of deaths caused = hazard

• Economic Loss: Value of assets damaged/lost = hazard

• Spatial Predictability: Predictability of which areas will be affected by a hazard event

Hazard Models

Tools used to evaluate and predict hazards, but may be less effective due to unpredictability

Volcanic Explosivity Index (VEI)

Measures the relative explosiveness of a volcanic eruption

Modified Mercalli Scale

Measures the destructiveness of an earthquake based on human perception

Moment Magnitude Scale

Measures the amount of energy released in an earthquake

Richter Scale

Measures the amplitude of waves produced during an earthquake

Hazard Management Cycle

Stages of responding to hazards, including preparedness, response, recovery, and mitigation

1. Preparedness: Being ready for a hazard event through public awareness, education, and training

2. Response: Immediate actions taken after a hazard event, such as evacuation and medical assistance

3. Recovery: Long-term responses to restore services and reconstruct after a hazard event

4. Mitigation: Strategies to lessen the effects of future hazard events.

Monitoring and Prediction

Forecasting hazards based on statistical likelihood and monitoring equipment

Local Aid and International Aid

Short-term and long-term recovery efforts after a hazard event

Management Approaches

Modify the Event, Modify the Vulnerability, Modify the Loss

Land use zoning (modify)

Preventing building in high-risk areas to reduce vulnerability

+ low cost,, reduces vuln. - stops econ dev on high profit land.

Resistant buildings (modify)

Structures designed to withstand hazards and protect people and property.

+prevent collapse, protect ppl/property. - high costs

Tsunami defenses (modify)

Sea walls and coastal forestry to reduce damage from tsunamis

+ reduces damage, provides security - high cost, unaesthetic

Lava diversion (modify)

Barriers and water cooling used to divert and slow down lava flow.

+diverts lava, low cost - only for low VEI lava.

Hi Tech Scientific Monitoring (modifying vuln)

Monitoring volcano behavior to predict eruptions.

Community Preparedness and Education (modifying vuln)

Low-cost measures implemented by NGOs to save lives through small actions.

Adaptation (modifying vuln)

Moving out of harm's way and relocating to save lives and property.

Short term aid (modifying loss)

Search and rescue, food, water, aid, and shelter provided immediately after a disaster.

Long term aid (modifying loss)

Reconstruction plans to rebuild an area and improve resilience.

Risk Poverty Nexus

Poverty as both a contributing factor and consequence of natural hazards.

What affects a community’s resilience to a hazard?

• Asset inequality – Relates to housing and security of tenure and also agricultural productivity.

• Political inequality – Where certain groups of people, usually the wealthy and elite, hold quite a lot of power and political influence.

• Social status inequality – Often directly linked to space and has a bearing on other dimensions of inequality, including the ability of individuals and groups to secure regular income and access services.

• Entitlement inequality – Refers to unequal access to public services and welfare systems as well as inequalities in the application of rule of law.

Hazard Vulnerability

Factors contributing to a population's vulnerability to hazards.

Unstable political governance and/or corruption

Lack of political cohesion impacting preparedness, response, and recovery efforts.

Population density

Higher population density leads to more people affected by hazards.

Geography isolation and accessibility

Remote, rural areas with poor transport links negatively affecting rescue efforts.

Level of urbanization

Urban areas worse affected by hazards due to population density and infrastructure damage.

Meeting basic needs

When food supply, water supply, and health needs are met, the population is less vulnerable to secondary hazards.

Planning

Land-use planning to reduce risk and prevent people from living in high-risk areas.

Preparedness

Education and community preparation programs to raise awareness and teach disaster response.

Corruption

Government corruption increasing vulnerability by diverting funds from crucial areas like emergency services.

Tectonic Mega-Disasters

Large-scale disasters affecting a large spatial area or population.

Pose problems in effective management to minimise the impacts.

Scale of the impact may require international support and aid.

Low probability (rare).

Globalization of production and supply chains

Allowing international businesses to reduce costs and become more efficient. Mega-disasters significantly damage globalised businesses

Business disruption examples

1. 2011 Tohoku earthquake & tsunami - knock on effect for TNCs e.g Toyota & BMW = operate + source products from Japan = lost potential revenue for those TNCs, caused general econ uncertainty.

2. 2011 Eyjafjallajökull eruption - significant ash cloud closed European air space = halt of goods & trade into the EU by air = Kenyan flowers couldn't be transported & wilted.