Restless Earth Flashcards
Which are the two types of crust and their main two properties?
Oceanic - denser and thinner (5km thick)
Continental - less dense and thicker (30km thick)
How can we detect the direction of the earths magnetic field?
When the magma oozing out of mid-ocean ridged solidifies into rock, the rock records the direction of the earth’s magnetic field.
What are the benefits of the earth’s magnetic field?
It protects us from outer space by forcing any dangerous particles from space to move around the earth.
Animals can also detect the field and use it to direct them.
At which plate boundaries are volcanoes:
- shield
- composite
And why?
Constructive plate boundaries have shield shaped volcanoes because the lava is runny so it flows very far before setting.
Destructive plate boundaries create composite volcanoes (steep sides) because the lava cools and sets quickly.
What type of earthquakes are created at:
- constructive plate boundaries
- destructive plate boundaries
Constructive plate boundaries produce weak shallow earthquakes as basalt is pushed into the thin crust.
Destructive plate boundaries produce strong earthquakes which can be either shallow (caused by friction as the dense oceanic plate sinks under) or deep (as the sub ducting plate melts)
What are the Sichuan earthquake primary impacts?
- 70,000 deaths
- 7000 schools destroyed
- 169 hospitals collapsed
- 80% of houses in Beichuan city destroyed
- 4.8 billion people are left homeless
What are the Sichuan earthquake secondary impacts?
- the government allows foreign aid workers
- 1.4 million in poverty due to job loss
- 1 child policy lifted for parents who lost a child
- Mudflow triggered by rainfall 5 days after the earthquake
- $150 billion worth of repair
What are the Mt Merapi Indonesia vocano primary impacts?
- over 100 deaths
- 75,000 residents evacuated
- explosions felt 20km from volcano
- 35 pyroclastic flows up to 10km
What are the Mt Merapi Indonesia vocano secondary impacts?
- deceased had to be buried in quickly to prevent disease which meant that they were not given proper funerals
- planes affected by ash clouds
- heavy ash fall
What were the Icelandic (Eyjafjallajokull) eruption primary impacts?
- daylight hidden from ash clouds
- crops destroyed
- road transport blocked
What were the Icelandic (Eyjafjallajokull) eruption secondary impacts?
- ash on aircrafts destroyed airport economy
- water supply damage
What is the VEI?
The Volcanic Explosivity Index
What were the Indian Ocean Tsunami primary impacts?
- 230,000 deaths
- coral reef damage
- crops destroyed
- over 100 schools destroyed
- 8 millions litres of oil lost
- coastline forests destroyed
- fishing industry destroyed
What were the Indian Ocean Tsunami secondary impacts?
- tourism economy destroyed
- reconstruction costs billions of dollars
- road transport blocked
- threat of disease as drinking water becomes contaminated
- 6 million people require emergency aid
How does continental drift occur?
The heat from earth’s core creates convection currents in the mantle (caused by radioactive decay). This hot molten rock rise and moves the plates on the surface which form the crust.
