Natural hazards Flashcards
(30 cards)
What are natural hazards
- It is something which is caused naturally and not man-made.
- it is only refered to a natural “hazard” if it puts people or buildings in danger. like a volcano with no ine around it is not a hazard
- they can cause social or economic impacts
what does social impact mean
it means ipacts on peoples lives
what is a economic impact
it is a impact on jobs and money
what are some examples of weather hazards
- tropical hazard
- droughts
- tornadoes
- flooding
what does a natural event mean
a non man amde event that does not pose threst to humans
what is a natural disaster
a non man made event which causes more than 10 deaths or more than 100 socially impacted and 1 million dollars of economic loss
what are enviromental affects
they are impacts on the natural enviroment
what do you need to do when it gives a graph with stats
refer back to it and give dates
what is the order of the earths stucture
- inner core
- outer core
- mantle
- crust
what are the two types of crust
- continental crust- thick but less dense (granite)
- oceanic crust- thin but dense (basalt)
what is the continental drift theory and give evidance
a weather man called alfred wegner on an expedition thought that all of the continents fitted together and was once a whole. the evidance for this is that the same tyles of rock are found on the shores of where the continents wouldve been if they were together and also it was like a jigsaw fit.
in the alfred wegner theory what was the supercontinent called when it was together
pangea
Explain convection currents
- So the earths heat, heats up the magma in the mantle. The heated magma is less dense and so it rises through the mantle.
- As it reaches the top of the plate, the magma spreads out under the plates dragging them apart.
- Where two convection currents sink, the two plates pull together.
- Then the magma cools down and gets more dense and so it sinks down to the bottom to do the process again. Making volcanoes or earthquakes
Where are most volcanoes and earthquakes found
Edge of plate boundaries
What are the four types of plate boundaries
Constructive, destructive, collision, conservative
What is a constructive boundary
Plates move apart due to convection currents. As the plates move apart the magma rises and erupts. This process happens multiple times and the magma hardens making a mountain (volcano)
What is destructive boundaries
Convection currents make the plates pull together. One is denser (oceanic crust) and it gets subducted. The rock gets stuck and then jolts suddenly making earthquakes. The movement as the plate is subducted heats up the rock and melts it. The molten rock is then forced up and erupts to form a volcano
What are collision boundaries
Two plates which are similar density collide due to convection currents. As they are similar density, they don’t subduct. With extreme pressure, the plates fold up to form mountains e.g. Himalayas
What are conservative boundaries
Plates slide across each other in different speeds. Parts of the plates get stuck and then jolt suddenly causing earthquakes. Friction causes earthquakes. No volcanoes as no gaps or subduction happens.
What is an active, dormant and an extinct volcano
- active means that it can erupt at any time
- dormant means that it is (sleeping). it could still erupt but it can go to sleep for a long while
- extinct means that it is dead and wont erult again.
What is the crater
A hollow tunnel shape space at the top of the volcanic cone
What is the secondary vent
If the main vent gets blocked with magma it is forced to go to the secondary vent
What is the ash cloud
A large cloud of smoke and dust that forms over the volcano
What are volcanic bombs
Balls of hot magma erupted and thrown into the air that solidify and hit the ground
