global hazards Flashcards
Ferrel cell
Middle cell where air flows poleward between 60° & 70° latitude.
Hadley cell
Largest cell which extends from the Equator to between 30° to 40° north & south.
Polar cell
Smallest & weakness cell that occurs from the poles to the Ferrel cell.
UK Heat Wave 2003
The heat wave was caused by an anticyclone (areas of high pressure) that stayed in the area for most of August. This blocked any low pressure systems that normally brings cooler and rainier conditions.
Effects (UK heat wave)
*People suffered from heat strokes and dehydration.
* 2000 people died from causes linked to heatwave.
* Rail network disrupted and crop yields were low.
Management (UK heat wave)
*The NHS and media gave guidance to the public.
* Limitations placed on water use (hose pipe ban).
* Speed limits imposed on trains and government created ‘heatwave plan’.
Typhoon Haiyan 2013
Started as a tropical depression on 2rd November 2013 and gained strength. Became a Category 5 “super typhoon”.
Effects (Typhoon Haiyan)
*Almost 4,000 deaths.
* 130,000 homes destroyed
* Water and sewerage systems destroyed caused diseases.
* Emotional grief for lost ones.
Management (Typhoon Haiyan)
- The UN raised £190m in aid.
- USA & UK sent helicopter carrier ships deliver aid remote areas.
- Education on typhoon preparedness.
Shield Volcano
Made of basaltic rock and form gently sloping cones from
layers of runny lava.
Location: hot spots and constructive margins.
Eruptions: gentle and predictable
Composite Volcano
Most common type found on land. Created by layers of ash
and lava.
Location: Destructive margins
Eruptions: explosive and unpredictable due to the build of
pressure within the magma chamber.
Hotspots
These happen away from any plate boundaries. They occur
because a plume of magma rises to eat into the plate above.
Where lava breaks through to the surface, active volcanoes
can occur above the hot spot. E.g. Hawaii.
Nepal Earthquake, 2015
- The Indian and Eurasian plates move together at a collision plate boundary.
- On 25th April 2015, a shallow focus (15km deep) earthquake took place measuring 7.8 on the Richter Scale.
Effects (Nepal Earthquake)
*8635 people were killed
*19,009 people were injured
*Historical and religious buildings were destroyed
*Schools, health facilities and government offices had to close
*Landslides buried rural villages
Management (Nepal Earthquake)
*There was little warning due to the wealth of Nepal and difficulty in predicting earthquakes.
*NGOs and governments donated emergency short term aid eg. India donated blankets, water, doctors and food.
*Long term – ‘cash for work’ schemes were set up to rebuild communities and provide money.
Destructive Plate Margin
When the denser oceanic plate subducts beneath the continental plate in a process called subduction. At the point of collision, the oceanic plate bends and a deep ocean trench is formed. The continental plate buckles, creating fold mountains. As the plates drag against eachother, and crack and fold, earthquakes are triggered. As the oceanic plate subducts into the hot mantle, the water helps it to melt. The water make the melted mantle less dense, so it may rise up through cracks in the continenalt plate as volanic eruptions.
Constructive Plate Margin
Here two plates are moving apart causing new magma to
reach the surface through the gap. Volcanoes formed along this crack cause a submarine mountain range such as those in the Mid Atlantic Ridge.
Conservative Plate Margin
A conservative plate boundary occurs where plates slide
past each other in opposite directions, or in the same direction but at different speeds. This is responsible for earthquakes such as the ones happening along the San Andreas Fault, USA.
Collision Plate Margin
Collision zones form when two continental plates collide. Neither plate is forced under the other, and so both are forced up and form fold mountains. These zones are responsible for shallow earthquakes in the Himalayas.
Causes of Earthquakes
Earthquakes are caused when two plates become locked causing friction to build up. From this stress, the pressure will eventually be released, triggering the plates to move into a new position. This movement causes energy in the form of seismic waves, to travel from the focus towards the epicentre. As a result, the crust vibrates triggering an earthquake.
Shallow Focus
-Usually small and common.
-Seismic waves spread and damage wide area.
Deep Focus
-Occur on destructive margins.
-Damage is localised as seismic waves travel vertically.
Mercalli Scale
Measures how much damage is caused, based on observations, not scientific instruments.
Richter Scale
Is a scientific measurement based on the energy released.
