🌋 Physical: Volcanoes and Earthquakes Flashcards
What is a natural hazard?
A natural event that threatens people or has the potential to cause damage, destruction and death
Name the 3 different types of plate margins.
Destructive, constructive and conservative
What is a destructive plate boundary and what type of tectonic hazards may be created here?
Two plates converging together and the oceanic plate being subducted as it is denser. Earthquakes and volcanoes.
What is a constructive plate boundary and what type of tectonic hazards may be created here?
Rising magma adds new material to plates that are moving apart. Earthquakes and volcanoes.
What is a conservative plate boundary and what type of tectonic hazards may be created here?
Two tectonic plates sliding next to each other. Only earthquakes.
What is an immediate response?
The reactions of people as a disaster happens and in the immediate aftermath.
What is a long-term response?
Later reactions that occur in the weeks, months and years after an event.
What is monitoring?
Recording physical changes, such as earthquake tremors to help forecast where and when a natural hazard might strike.
What is planning?
Actions taken to enable communities to respond to and recover from natural disasters through measures such as emergency evacuation.
What is prediction?
Attempts to forecast where and when a natural hazard will strike based on current knowledge.
What is protection?
Actions taken before a natural hazard strikes to reduce its impact.
What are primary effects?
The initial impacts of a natural event on people and property caused directly by it.
What are secondary effects?
The after effects that occur, sometimes on a larger timescale.
How do convection currents work?
- The hot core causes magma to rise in the mantle and sink towards the core when it cools.
- Convection builds pressure and carries plates with it.
How does slab pull work?
- The denser plate sinks back into the mantle under the influence of gravity.
- It pulls the rest of the plate along behind it.
How does ridge push work?
- Magma rises as the plates move apart.
- The magma cools to form new plate material.
- As it cools it becomes denser and slides down away from the ridge.
- This causes tectonic plates to move away from each other.
Why do earthquakes occur at a destructive plate margin?
The plates stick and there is a build up of pressure which is suddenly released.
How are volcanoes formed at destructive plate margins?
The oceanic plate boundary gets subducted and then melted in the mantle which then rises as hot magma and forms a volcano. The build up of pressure is the released as an eruption.
What is the type of plate boundary found on Eyjafjallajökull and what are the names of the two plates?
Constructive. Eurasian and North American.
Describe the location of Eyjafjallajökull?
Southern Iceland, 2km from the coast. West of Katla and South of Hekla. SE of Reykjavik 160km.
What were the main primary effects of the Eyjafjallajökull eruption in 2010?
- 150m of thick ice sheet melts
- Ash cloud reaches 6,000 - 10,000m and spreads in wind direction
- Thousands of tonnes of ash + steam plumes from melted ice forcing the ash higher
- Flash flooding
- Ash covers property and affects cattle
What were the main secondary effects of the Eyjafjallajökull eruption in 2010?
- 15th April 2010, all flights cancelled in and out of the UK because ash clogs fuel and cooling systems.
- 95,000 flights cancelled + by 17th & 18th flights were down to 5,000 per day rather than 25,000
- Hotel occupancy in London down 25%
- Shops ran out of flowers fruit and veg
What were the main immediate responses of the Eyjafjallajökull eruption in 2010?
- 20 farming families were evacuated
- Farm animals were moved into barns
- Trenches dug to allow floodwater to pass away without washing away bridges
What is the focus?
The point of origin of an earthquake within the earths crust.
