Natural/Tectonic Hazard

Natural Hazards

• Naturally occurring event with the potential to have a major threat to a population

• Negatively affect a population by damaging infrastructure/loss of life

• Natural events which do not pose any threat to human activity are not counted as hazards

• A natural hazard that occurs is called a natural disaster

Types of Natural Hazards
Type - Defintion

• Example

• Tectonic Hazards - Caused by land and tectonic processes

  • Volcanoes/Earthquakes

• Geomorphological Hazards - Occur on the earths surface

  • Flooding

• Biological Hazards - Caused by living organisms that pose a threat to human/environmental health

  • Covid - 19

• Atmospheric Hazards - Occur in the atmosphere

  • Hurricanes/Tornadoes

What is hazard risk (2)?

• Probability that a natural hazard will affect a population

• Dependent on Exposure/Vulnerability to the hazard

Factors Affecting Hazard Risk

• Vulnerability

• Capacity to Cope

• Nature of Natural Hazard

• Human Influences

Primary and Secondary Effects Examples

• Primary Effect

  • Immediate Impacts

  • eg. Road destroyed/Food and Water Supply damaged

• Secondary Effects

  • Happens after as a result of primary effects

  • Initial hazard trigger other hazards

  • eg. Eq → Tsunami / Shortages/ Aid and emergency vehicles cant get through because of blocked road or bridge (more deaths)

Immediate and Long Term Responses

• Immediate Response

  • Evacuate/Treat Injured/ Rescue/ Recover dead bodies to prevent disease spreading

  • Provide temporary electrcity/food/water

  • Aid such as financial/workers/supplies

• Long term response

  • Repair homes/infastructure

  • Reconnect broken water/gas/comms

  • Improve monitoring and evacuation plans

  • Boost economic recovery and improve building regulations

Oceanic Crust

• thinner and more dense 5-10km

• formed of basaltic rock

• sinks when it meet continental plates

• less than 200 million years old

Continental Crust

• thicker 20-200km

• composed mainly of granite rock

• up to 3.8 billion years old

Plate tectonic theory

• crust and upper mantle form a rigid shell at surface of earth called lithosphere

• broken into several fragments called tectonic plates

• which move slowly over the semi molten mantle asthenosphere

• the point where two plates meet is called a plate margin

Where do volcanoes occur

• Destructive margins (Composite Volcanoes)

  • ocean plate move down into mantle/melts/pool of magma forms rises through cracks in crust called vents/ lava when it reaches surface (eruption)

• Can form over parts of mantle that are really hot (hotspots)

• Emits lava/gases/pyroclastic flow

• Constructive Margins (Shield Volcanoes)

  • Magma rises up into gap made by plate moving apart

Where do earthquakes occur

• All three types of plate margin

• Destructive Margins

  • tension build when one plate get stuck as it moves past other

• Constructive Margins

  • tension build along cracks in plates as they move away from each other

• Conservative Margins

  • tension builds when plate that are grinding past each other get stuck

How do earthquakes form + info

• Jerk past each other sending out shockwaves

• Spread out from focus closer to the epicentre stronger the vibrations

• epicentre is point of surface above focus

• Richter scale - logarithmic scale

Constructive Plate Margins

• occur when two tectonic plates are moving away from each other

• magma rises from the mantle to fill the gap in the crust

• this cool down and becomes denser to form a new crust

• magma is buoyant enough to eventually create a shield volcano

• Eg: Movement of Eurasian plate and north American plate forming the mid Atlantic ridge

Destructive Plate Margins

• occurs when two plates are moving toward each other

• oceanic plate meets continental plate the deeper oceanic plate is subducted and destroyed creating gas rich magma

• Volcanoes and ocean trenches occur

• When two continental plates meet the ground is folded upward creating fold mountains

• Eg. West coast of South America ocean NAZCA plate subducted beneath south American plate creating Atacama Trench

Conservative Plate Margins

• Where two plates are moving sideways past each other

• Or in same direction at different speeds

• Crust isnt created or destroyed

• Eg. San Andreas Fault Pacific Plate moving in the same direction as the North American plate but faster

Reasons why people still live in high risk areas

• Historical ties - Many have lived in these areas for generations, making relocation difficult as it involves leaving behind family, friends, and livelihoods

• Economic benefits - Volcanic soil is highly fertile and ideal for agriculture due to mineral enrichment

• Tourism opportunities - Active volcanoes draw visitors, creating employment in tourism sector and may have multiplier effect

• Confidence in safety measures - Advanced monitoring systems and evacuation plans reduce perceived risks in developed regions

• Government support - Residents trust that authorities will provide aid such as financial assistance or tax relief following disasters

• Energy → Volcanic areas geothermal energy can be harnessed by using steam from underground heated by magma

4 Key approaches to managing a hazard

1. Monitoring - Using advanced technology to detect early signs of tectonic activity, providing critical warnings to save lives

2. Prediction - Forecasting potential events by studying geological patterns, even if exact timing remains challenging

3. Protection - Designing and retrofitting infrastructure to withstand the forces of nature, reducing structural damage

4. Planning - Preparing communities and emergency services to respond efficiently during and after a hazard

Monitoring Method for Earthquakes/Volcanoes

Earthquakes:

• Seismometers and laser-based systems track ground movements
• Form the basis of early warning systems that offer brief but crucial alerts before major tremors

Volcanic eruptions:

• Scientists observe precursor signs such as minor tremors, gas emissions, and deformations in the volcano's shape
• These signs help anticipate when an eruption might occur

Protection techniques against earthquakes

• Modern building design - Buildings incorporate energy-absorbing materials like reinforced concrete

• Retrofitting older structures - Steel reinforcements added to prevent collapse

• Automatic shut-off systems - Gas and electricity systems automatically shut off to avoid secondary dangers like fires

Protection techniques against volcanoes

• Structural fortification - Buildings can be strengthened to bear the weight of ash deposits

• Lava flow redirection - Trenches or barriers are used to attempt to redirect lava flows, though success rates are limited

Planning measures for emergency response to tectonic hazards

• Avoiding high-risk zones - Future construction and urban development steered away from vulnerable areas

• Emergency service readiness - Regular drills ensure response teams are well-prepared

• Community education - Teaching residents about safety protocols and actions to take during hazards

• Evacuation planning - Clear routes designed to facilitate swift and safe evacuation

• Stockpiling supplies - Essential items like food, water, and blankets stored in advance for immediate relief

Why is volcanic soil useful?

Volcanic soil is enriched with minerals, making it highly fertile and ideal for agriculture. This creates significant economic benefits for farming communities living in these areas.

Purpose of management strategies

Management strategies aim to minimise the impact of tectonic hazards by lowering the number of casualties, injuries, homelessness, and unemployment caused by earthquakes and volcanic eruptions through proactive and reactive approaches.

Factors - Effecting Hazard Risk (Vulnerability)

• Vulnerability

  • Increased population more people to interact with natural hazards

  • Cant Move - Due to lack of knowledge/Expense/Language Barrier

  • Worth staying - due to jobs/resources

Factors Affecting Hazard Risk - Capacity to Cope

• Capacity to Cope

  • Better a population can cope lower the risk of event eg. HIC can afford defences so less damage

  • Can accurately predict hazard - Location/Magnitude/Timing

  • Overconfident in defences/Optimist it wont occur

Factor affect hazard risk - type of hazard

• Nature of Natural Hazard

  • Some hazard carry greater risk than others (due to time it take to predict and evacuate)

  • Some a frequent and may carry higher risk

  • Magnitude higher the severity greater the effects

Factor Affecting Hazard Risk - Influences

• Human Influences

  • GHG - extreme weather

  • Deforestation - flooding etc.