Hazardous Earth section 14 and upwards Flashcards
What is the lithosphere?
- Uppermost layer of the Earth
- Cool and brittle
- Solid physical state
- Composed of granite with temp of 900c
What is the mantle?
- Largest of the Earth’s layer by volume
- Mostly solid rock
- Composed of peridotite
- Temp between 1600-4000c
What is the core?
- Composed of iron and nickel
- Temp between 4000-5000c
- Outer state is liquid and inner is solid
What is the asthenosphere?
- Hotter and more fluid than the lithosphere
- Upper layer of the Earth’s mantle
What are the key differences between the continental crust and the oceanic crust?
Continental crust is a solid the same as the oceanic crust, the continental is less dense and the composition of the continental crust is granite whereas its basalt for oceanic
What is a plume?
The parts of convection cells where heat moves towards the surface, these are concentrated zones of heat, in a plume the mantle is less dense
What would happen to life if convection stopped?
The tectonic plates would stop moving and we would all die because of it
What is the movement of a divergent plate boundary?
As the plates move apart, magma rises up through the gap. The magma is basalt and very hot and runny. It forms lava flows and shallow sided volcanoes. Earthquakes are formed due to friction as the plates tear apart.
Why are some plate boundaries more hazardous than others?
Convergent plate boundaries are destructive and can cause destructive earthquakes up to magnitude of 8.5 whereas divergent has a risk of small earthquakes up to 5.0-6.0
Why are supervolcanoes so destructive?
Due to the size of the magma chamber underneath them for example the magma chamber under Yellowstone is the size of New York, at 1000km3 of magma
How are tsunami’s formed?
- Mostly caused by earthquakes
- A plate shifts abruptly causing an earthquake
- Waves are generated and move out in all directions across the ocean as fast as 600mph
- As the waves get into shallower water, they compress and they build in height
What are the primary impacts at the Japan earthquake?
- 1 dam collapsed
- 2 nuclear power stations fractured
- Motorway badly damaged
- US 35 billion dollars of damage caused
What are the secondary impacts at the Japan earthquake?
- 15900 people died, 2600 missing, 6150 injured and 350,000 homeless
- 93% of deaths caused by drowning
- Two nuclear reactors went into meltdown because of flooding
What preparation was there at the Japan earthquake?
- Tsunami walls designed to protect the coast
- Tsunami warnings
- Alarms sounding to evacuate
- Buildings can be made earthquake proof
What was the response given at the Japan earthquake?
- Good evacuation
- Mobile generators deployed
