Natural hazards and disasters

Radioactive material causes magma to rise
Melts plate above causes volcanoes to form
Plate moves over the hot spot
Causes chain of volcanoes to form

Caused by stresses within plate
Plate stretched over spherical surface
Weaknesses are caused
Earthquakes happen along zones of weakness or ancient boundaries

Ortelius - suggested they look the fit like puzzle
Wegner - once joined in a super continent called Pangea, had drifted apart over time
Harry Hess - suggested convection currents, recycling of plates

Evidence
Split fossil remains (India and Australia)
Rocks found in Scotland and new found land
Mountain range cut in half between Brazil and Africa
Glacial deposits found in hot countries suggesting they were once in cold regions

Paleomagnetism
Occurs at constructive plate boundaries
Alternate bands of magnetic material (found in basalt)
Shows how new layers are produced by Earth
Shows magnetic field changes

Wilson cycle
See folder for diagrams
Hot spot causes to split in two
Causes the plates to travel further apart
Closes when newly formed oceanic plate sinks under continental
Continental ends up traveling towards previous continental
Eventually the continental plates collide
Causes a collision boundary = mountains

Basalt
Hot, thin, low silica, high iron
Easy for gas to escape so a peaceful constant eruption

Rhyolite
Cool, thick, high silica and low in iron
Hard for gas to escape so an irregular eruption

Andesite is in the middle of the above
So intermediate eruption and gas escape

Destructive boundary formed
Pressure builds up
Continental flicks up displacing water causing it to bulge higher then usual
Gravity pulls it down causes the wave to split and travel in separate directions

Wave is nearly undetectably
Travels at 500mph

Draws closer to shore the topography is shallower
This causes the front of the wave to slow down while the back is still moving faster
Results in a wall of water known as a tsunami

Body waves- travel through inner layers
Surface waves- along surface like ripples on water

Order
Body waves and the surface waves which are the ones that cause the most damage

P waves
Longitude waves, same direction of travel

S waves
Arrive second, transverse waves. Look wavy side on

L waves
fastest wave that moves ground from side to side, confined to surface of crust, horizontal motion so looks wavy from birds eye view

Energy generated in shallow events is released closer to the surface and therefore produce stronger waves on the surface

Green = most dangerous
Yellow = bit less dangerous
Red = least dangerous

Natural hazard - a perceived natural event which has the potential to threaten life and property

Can either be:
Geophysical (tectonic)
Hydrometerological (weather)

Risk equation
Risk=magnitude x vulnerability/ capacity to cope

Ability of individuals, communities, organisations and states to adapt to and recover from hazards, shocks and stresses without compromising long term prospects for development

Degree in which countries can learn from past experiences/ disasters and reduce risk for future events

Mega disaster- unexpected natural disaster of exceptional magnitude or caused severe damage

Socio-economic - study of social and economic factors to understand how the combination of them influences something

Spatial predictably- using patterns and areas past hazards have occurred to predict future events

Dynamic pressures - things that effect how vulnerable a community is e.g rapid migration, social structure, local markets and macro forces

Liquefaction - process of loose soil actions like a liquid

Venn diagram
Vulnerability on one side. Hazard on the other side.
Overlap represents the disaster

Therefore when a hazard comes in contact with a vulnerable population = disaster

Weighing up the vulnerability and the hazard against each other to discover what made the hazard a disaster

Vulnerability side
Root causes
Political and economic systems e.g debt or political instability

Dynamic pressures
Local systems
Organisations
Population

Unsafe conditions
The conditions resulting from the two previous e.g poorly built buildings resulting from lack of building codes and large population

Hazards
Information about the hazard e.g magnitude, severity, impacts e.g deaths

Poverty- illegal housing - dangerous areas
Poverty- slums- poorly built- homeless after

Currpted government- lack of preparation, education systems, disaster management- unable to bounce back and responses were slow

Wealth- can't pass building codes- portly built houses- unsafe conditions

Support from aid- if already getting support- will need more after- too reliant- can't rebuild

A diagram that shows the main characteristics at different types of tectonic hazards or multiple hazards to allow for easy comparison

(Place dots between scale) e.g speed of onset, rapid - slow
Characterises which make the hazard worst on one side

Then connect the dots to create a zig zag

These can be compared