Geography Natural Hazards

Constructive Plate boundaries-

Where 2 plates are moving apart allowing larva to escape from the crevic to create a gentle eruption and the lava flow forms mid ocean ridges

Conservative Plate boundaries-

Where 2 plate boundaries try to slide past each other, pressure then builds up to create large earthquakes but no volcanic eruption

Destructive Plate boundaries-

Oceanic crust moves towards the continental crust causing a pressure increase which causes earthquakes and magma is pushed up in volcanoes

Collision Plate boundaries-

When the 2 plates moving are continental crusts the land between them buckles and is pushed up to form mountain, earthquake may also occur

Structure of a Volcano- key features-

Magma chamber store of molten rock, layers of ash and lava make up the body of the volcano from previous eruptions, crater at the top of the volcano, usually a secondary cone forms if the main vent is blocked

Impacts of volcanoes-

Primary- Deaths, homes destroyed, transport routes destroyed, natural landscape and crops destroyed

Secondary-Overcrowding in refugee centres, loss of business, water and sewage systems damaged, explosions and fire from broken gas pipes, rise in unemployment

Preparing for a Volcano-

Monitored using tilt metres to measure angle of the slope, laser ranging and aerial photography to see any bulges, volcano hazard maps showing evacuation routes and large water reserves to cool lava 

Causes of Earthquakes-

Earthquakes occur near to tectonic plate boundaries, this is do to the movement of the plates (caused by convection currents in the mantle) causing friction and vibrations through the earth

Impacts of Earthquakes-

Buildings collapse, deaths, homelessness, breakdown of society (looting), spread of water borne diseases like choloria

Preparing for an earthquake-

Earthquake Proof Building-steel fames that move, rubber shock absorbers in foundations, easy evacuation route, made of fire resistant materials, window shutters that prevent falling glass, open area around it

Others- 'What to do in an Earthquake' leaflets, preparation pack (rations, touch, first aid kit etc), have an earthquake plan, know how to turn off gas, water and electricity.

Causes of Tsunamis-

Tsunamis occur when earthquakes happen in the ocean, the vibrations and movement of land cause huge waves which travel large distances

Impacts of Tsunamis-

Death, loss of business, unemployment, flooding, damage to crops and landscape, and economic decline

Preparing for Tsunamis-

Early warning systems located deep in the ocean-Pressure sensors on sea bed measure height and of Tsunami, sensors then send data to buoys for relay to satellites, tsunami centre issue alert

Tsunami proof safe houses (on stilts),megaphone (warn people) 

How Tropical Storms Form-

Thunderstorms drift over warm seas, warm are from both thunderstorm and sea starts to rise, due to earth rotation warm air spirals, it cools and forms clouds which releases much energy, cool air is sucked downwards and wind speeds increase, 

Impacts of a Tropical Storm-

Death, flooding, homes and building destroyed, loss of electricity, looting, homelessness, lack of food and water, crime increase, lack of infastructure

Preparing for a Tropical Storm-

Cyclone shelter (on stilts), embankments to prevent flooding, emergency survival kit, boarding up windows, satellite tracking systems, and megaphones for alarms

Causes of Forest Fires-

Lightening, volcanoes, spontaneous heating, broken bottles, arson, cigarettes/matches and lighters.

Santa Ana wind is winds in california that come from the desert so they make wildfires worse because they blow hot air on to the fires

Impacts of Wild Fires

Land damaged, ecosystems damaged, high Co2 pollution, people made homeless, loss of jobs, insurance cost go up, tourism lost and farming money lost

Preventing Wildfires

Posters and signs for awareness, no smoking areas, GIS, plan building away from forests, collect all debris  from ground that could light, first aid kits, Smokey the Bear!

El Nino is where the warm water brought over from South America to Australia swaps over and stay near to South America.

This means that warm water causes heavy rain in the South American deserts causing flooding. the cold water left in Australia then leads to drought as non is evaporated to clouds and rain

Latitude-

 Places nearer to the equator get a greater concentration of rays meaning they are hotter, Places further away get a small concentration and are therefore colder

Distance From the Sea-

Places further inland have a greater range of temperatures ie. they have hot summers and cold winters. Places on the coast have a smaller range ie. warmer winters and cooler summers

Prevailing Wind-

The direction from which the wind comes from will effect the temperature. From Alaska = colder temperature, from Asia = warmer temperature

Altitude-

The temperature decreases the higher above sea level you go

Convectional Rainfall-

Rain is caused by water on land being heated by the sun and evaporating before forming clouds which then rain (continual cycle)

Relief Rainfall-

Warm water from oceans reaches land, it then travels over mountains, rising air is cooled, condenses and clouds form. Further cooling and condensing means heaving rain. Descending air is warm, and evaporates to form clouds, evaporating gives rain shadow effect.

Frontal Rainfall-

Cold air undercuts warms air on the land, forcing warm air up to for clouds and rain

Geothermal Energy- Steam from water heated by hot rocks below the surface drives turbines to generate electricity

Mineral Extraction- Many valuable minerals form when volcanic activity occurs

Raw Materials- The raw materials for many products come from volcanoes, these include building materials and chemicals used in industry

Fertile Soil- Volcanic rocks are rich in minerals and when weathered, for fertile soil, these are ideal for growing crops

Tourism- Volcanic landscape can have very beautiful scenery due to rich ground and this attracts visitors