Geography IGCSE - Hazardous environments

Hazards

An event that threatens, or actually causes damage and destruction, to people to their property and settlements

Natural hazards

A hazard produced by environmental processes and involves events such as storms, floods and earthquakes and volcanic eruptions

Why are some places more hazardous than others

some places, experience more than one type of natural hazard event, experience natural hazards more frequently, where the hazards are stronger and more destructive, are better able to cope with the damaging impacts of natural hazards

Geological hazards

Earthquakes, landslides, volcanic eruptions

Climatic hazards

storms, floods, drought

Biological hazards

fires, pests, diseases

Technological Hazards

nuclear explosions, accidents, pollution

Draw how tropical cyclones are formed

P.67 of Edexcel book

Conditions for tropical cyclone

deep layer of humid, warm (>27) and unstable air, supply of energy from surface of the sea, circular motion of the air, encouraged by Coriolis force, wind shear encourages the circulatory motion within the cyclone

Calmest part of a tropical cyclone

eye

Most destructive part of the eye

eye wall

Difference between hurricanes and cyclones

hurricanes in America, cyclones in Indian Ocean, typhoon in Pacific

effects of tropical cyclones

very strong winds, torrential rain, storm surges

Storm surges

rises in sea level associated with very low pressure, allows the sea to expand

Divergent/Constructive

When two plates are moving apart. Convection currents move plates. Up-welling of magma from the mantle creates new oceanic crust. Volcanic islands and mid-ocean ridge are created

Destructive/Convergent/Subduction

Convection currents in the upper mantle move plates. Denser oceanic plate is subducted beneath the continental plate. Ridge-push and slab pull forces pull the plate under and break it up. Increase in pressure causes earthquakes and volcanic eruptions

Conservative/Transform

Two plates move in opposite directions or in the same direction at different speeds. The friction may cause an earthquake

Collision

Two plates meet head-on and are of equal density and strength because of convection currents. The sediments between the two plates are squeezed upwards

Hotspots

location beneath the Earth's crust where strong and rising currents of magma occur

Different types of hazards from volcanoes

Lava flows, ash, gas emissions

Pyroclastic flows

a dense, destructive mass of very hot ash, lava fragments, and gases ejected explosively from a volcano and typically flowing at great speed

Earthquakes

Sudden and brief period of intense shaking of the ground

Measuring scale of explosivity

Volcanic Explosivity Index (VEI) which measures the volume of ejected material and eruption lava height

Scale of VEI

0-8

When magma erupts at the surface it can form different types of volcanoes depending on...

viscosity, stickiness, amount of gas, way it reaches surface

Two types of volcanoes

explosive, effusive

High viscosity

high explosivity

low viscosity

Effusive explosivity

Strato Volcano (composite cone)

viscous magma, explosive eruption

shield volcano

Low viscosity, effective eruption

Measure of earthquake

Richter scale

Epicentre

point on the surface directly above the centre

Focus

centre of the earthquake underground

Richter scale

used to determine the likely damage caused by an earthquake

The amount of earthquake damage depends...

on the depth of the focus and the type of rock

The worst damage occurs where the...

focus is closest to the surface and where rocks are soft

Shock waves...

liquefy soft rocks so they behave like a liquid. Rocks lose their load-bearing ability. The foundations of buildings and bridges collapse

The hazard threat of earthquakes lies in their ability to...

shake buildings so vigorously that they fall apart and collapse. The damage is worse than it should be because of poor building design. They also rupture gas pipes and break electricity cables

Mercalli scale

scale that is based on what people experience and the amount of damage done

Moment Magnitude Scale (MMS)

scale which measures the energy released by an earthquake on a logarithmic scale. (More accurate than Richter scale)

The amount of damage and destruction caused by a particular natural disaster does not just depend on its scale and destructive energy. Other factors are...

size of area affected/ density of population/ how long the event lasts/ degree to which people are warned in advance of event/ level of preparation/ ability of country or region affected to cope with aftermath of hazard

Primary effects of earthquake...

collapsed buildings and people killed by this/ broken water, gas and sewage pipelines/ downed electric power lines

Secondary effects of earthquake...

tsunamis/ aftershocks/ fires due to ruptured gas mains

Primary effects of volcanoes

Buildings, roads, crops are destroyed by lava flows; ash causes roofs to collapse; people and animals are injured/killed by lava and falling rocks; water supplies are contaminated; people, animals and plants are suffocated by volcanic gases

Secondary effects of volcanoes

Lahars, fires, psychological trauma

Richter Scale

The Richter scale measures the magnitude of an earthquake (how powerful it is). It is measured using a machine called a seismometer which produces a seismograph. A Richter scale is normally numbered 1-10, though there is no upper limit. It is logarithmic which means, for example, that an earthquake measuring magnitude 5 is ten times more powerful than an earthquake measuring 4.

Reasons people live in high risk areas such as volcanoes

fertile soils, farming, tourism, mining, geothermal power, family

Reasons people live in high risk areas such as tropical cyclones

warm seas, tourism, climate, family

Reasons people live in high risk areas such earthquakes

geothermal power, tourism, feeling of protection, family

major short-term impacts of tropical cyclones

damage of property, people killed or injured, disruption of communities, decline in quality of life, disruption and destruction of businesses transport links and services, landslides, soil erosion, flooding

what causes primary impacts in cyclones

high winds, torrential rain, storm surges

major secondary-term impacts of tropical cyclones

cost of repairing the damage to the spread of waterborne disease, loss of homes and personal possessions, transport lines being blocked by landslides

Reasons for why developed countries cope better with the impacts of natural hazards

better access to resources and technology, better emergency services, quicker recovery,

Scale to measure wind speed

Saffir-Simpson hurricane Wind Scale

Ways to reduce the possible impact of future tropical cyclones (adjustment/ mitigation)

building design, location, warning systems, education

Adjustments to buildings to protect against hazards

curved roof for typhoon protection, base isolation system for earthquakes, 3m columns for flood, water can easily run off grass

Coriolis Force

exerted by the spin of the earth on a rotating system causing it to be deflected to the right in the northern hemisphere and to left in the southern hemisphere

why is Indonesia at greater risk from volcanic hazards (physical)?

area one of the most seismically active areas on the planet, subduction on the Indian Ocean, islands were formed due to volcanic activity, Indonesia sits on top of the meeting point of several tectonic plates

why is Indonesia at greater risk from volcanic hazards (social)?

Jakarta has 10 million people, high risk of infectious disease, 300 different ethnic groups use more than 700 languages, rural areas 20% of population don't have clean drinking water, 32% of the population is involved with agriculture

why is Indonesia at greater risk from volcanic hazards (economic)?

GDP per capita is $11 700, Indonesia imports $144.4 billions of good including fuel, 32% of population live below the poverty line,