Global Geographical issues: Hazards Flashcards
What is the focus of an earthquake?
The centre of the earthquake beneath the earth. If it is close to the surface (shallow) then it will be a powerful earthquake and if it is deep then it will be weaker.
What is the epicentre of an earthquake?
The centre at the surface of the earth
What is the top layer of the earth called?
The crust (made from tectonic plates)
What is the second layer of the earth called?
Mantle- divided into solid upper mantle and partially liquid lower core
What is the centre of the earth called?
The core- divided into liquid outer core and solid inner core
What are the differences between the oceanic crust and the continental crust?
- The oceanic crust is thinner due to being newer as it gets forced under the continental crust because it is denser
- the oceanic crust is mainly made from basalt
- The continental crust is thicker and less dense
- the continental crust is mainly made from granite
What causes tectonic plate movement?
Plumes of heat called COLUMNS caused by RADIOACTIVE DECAY of materials like uranium rise to the surface to create CONVECTION CELLS in the mantle. These convection cells push together (DESTRUCTIVE PLATE BOUNDRIES) or pull apart (CONSTRUCTIVE PLATEBOUNDRIES) tectonic plates causing them to move in the direction of their flow. `
What is the name of the process by which the oceanic crust gets pushed under the continental crust?
Subduction
What is a conservative margin?
Theresa mays new policy or
When two tectonic plates slide past each
other. The friction between the two plates causes earthquakes. Sometimes the two plates get stuck and the tension builds up until it suddenly slips, releasing a huge earthquake and a lot of energy.
What type of destructive plate boundary creates mountain ranges?
Collision plate boundries- two continental plates of low density granite collide, pushing up into mountains.
What happens at constructive plate margins?
As plates move apart, basalt magma rises up through the middle forming lava flows an shallow sided volcanoes e.g. Iceland
What happens at a destructive margin?
Plates are pushed together but the oceanic plate is subducted.
What hazards are brought by tropical cyclones?
- Strong winds-destroys vegetation and buildings
- Storm surges bring powerful, fast flowing floods
- intense rainfall-flooding-landslides
- Landslides/mudslides caused by saturated ground.
How do tropical cyclones form?
Warm air rises(when temperatures exceed 26.5c) from the ocean and more is drawn in to replace it, then rising as well. Up draughts contain a lot of water vapour which condense into cumulonimbus clouds creating heat to power it further. Coriolis force causes rising air to spiral. This speeds up with new air as it moves but slows down once it reaches a landmass as there is not enough moisture it decays into a storm.
Where do tropical cyclones form?
- in areas exceeding 26.5 c
- strong winds high up in the troposphere
- low pressure brought together by the itcz
- Over the sea where there is moisture.
What are the two different types of volcanoes?
Shield volcanoes and composite volcanoes
What are shield volcanoes?
- found along constructive plate boundaries
- formed by eruptions of thin runny lava which flows along way before solidifying
- gently sloping sides with a wide base
- contain basaltic magma
- erupt frequently but not violently
What are composite volcanoes?
- found on destructive plate boundaries
- formed by eruptions of lava and ash that don’t flow far
- steep sides and a narrow base
- andesitic magma which contain a lot of gas
- erupt rarely but violently
How are building built to prevent damage from earthquakes?
- Rubber or steel foundations to allow movement
- strong framework
- reinforced gas and water pipes
- a band of concreate on the roof to stop walls falling apart
What is the saffir-simpson scale?
What is used to measure the intensity of hurricanes in America