Flashcards in Global Geographical issues: Hazards Deck (50)
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?
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
-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
-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
What are the social, economic and environmental impacts of tropical cyclones?
-destroys homes and business's which also costs the government in taxes and support In rebuilding
-people starve due to crops being destroyed
-people become ill due to contaminated water sources which also costs in health care and loses taxes
-damages vegetation and destroys habitats
-loss of livestock, poo fuel, food, disease
-rubbish flowing into the sea
What techniques are used for protecting against cyclones? (think about +/-)
-storm surge defences
Where is an example of successful evacuation in preparation of a hurricane?
Hurricane sandy in 2012
What is the ITCZ?
The point at which two large cells of air converge. These cells consist of low pressure rising from the hotter land, cooling and sinking causing areas of high pressure.
How does the ITCZ bring west Africa's rainy season?
In July, African countries like mali are in their summer season so the land is hotter this means:
1) The hot land causes the air to rise and create an area low pressure
2)Further south over the sea, an area of cold, dense high pressure forms due to being cooler than land
3)wind blows from high to low pressure bringing moisture from the sea
4)Other winds blowing south towards west Africa bringing moisture from the sea
5)The two winds meet heat and rise to create tall cumulonimbus clouds as they call
6) heavy rain falls as the clouds condense
What are the theories behind climate change?
The eruption theory
The sunspot theory
The orbital theory
What is the volcanic eruption theory?
1) volcanic eruptions can change the earths climate
2) The blanket of ash and gas blocks out sunlight
3) this lowers the average temperature of the planet
4) If the ash and gas rises high enough, it enters the stratosphere and gets blown around the world by high winds
e.g. mount Pinatubo lowered the average temperature by 0.5'C
What is the sunspot theory?
That when there are more sun spots, more solar energy is released and therefore heats the earth up more.
What is the orbital theory?
The theory that global temperatures are affected by changes in the earths orbit changing shape ( circular to oval) and the earths axis wobbling and tilting, affecting how much solar energy reaches areas or earth.