1 Flashcards
How do constructive plate boundaries create new land (oceanic)?
As the plates move away from each other, they make a gap in the crust. This means the water will come into contact with the mantle. The water cools the mantle, turning it into rock and creating new crust.
How do constructive plate bounaries result in the formation of mountains or islands?
When the mantle rises through the gap between the plates, there are sometimes volcanic eruptions. This means that more magma has risen and can make a mountain. Lots of these eruptions can make an island, such as Iceland.
What occurs at constructive plate boundaries?
Volcanoes and Earthquakes
____ volcanoes can form at constructive plate boundaries, sometimes creating islands.
Shield
Give an example of a constructive plate boundary
The mid atlantic ridge
How fast do tectonic plates move in the mid atlantic ridge? (Constructive boundary)
Approx. 7 cm a year
What type of crust do collision plate boundaries use?
Both continental
What type of crust do constructive plate boundaries use?
Both oceanic
What happens at a collision plate boundary?
Two pieces of continental crust push together, forming fold mountains. Some of one of the plate could be also subducted underneath the other one.
What are fold mountains made of? Where do you find them?
-Collision boundaries
-Made of sedimentary rocks from the ocean. These oceanic rocks are uplifted when the mountains form (or fold).
Give an example of a collision boundary
The Himalayas
(Indian plate and Eurasian plate)
What hazards occur at collision boundaries?
Eathquakes (because of tension between the two moving plates)
What is a conservatinve plate boundary? What happens here?
Two plates move opposite each other or in the same direction at different speeds. They basically slide side by side.
Conservative
What is is called when two plates meet?
The fault line
Give an example of a conservative boundary
San Andreas fault line in California
What hazards occur at conservative boundaries?
Earthquake from the build up of friction and tension. The two plates could get jammed and then suddenly unjam, releasing lots of energy.
What is a destructive plate boundary?
It is when one plate goes under another (subduction). It happens with dense oceanic crust and less dense continental crust.
What is oceanic crust made of and what does this mean at a destructive plate boundary?
- CO2, fossils and Calcium Carbonate
- When the oceanic plate melts while subducting, it realeases the CO2, producing an eruption.
Oceanic crust is more __ but __
- Dense
- Thinner
What happens to the oceanic crust at a destructive plate margin?
It is less dense than the continental crust, so it gets subducted. This causes it to melt due to high temperatures (due to friction).
What is it called where the oceanic crust is getting subducted under the continental crust (destructive)
The subduction zone
What is formed when the two plates meet at a destructive margin?
A deep ocean trench
Give an example of a destructive plate margin
South American plate and Nazca plate
What occurs at destructive plate boundaries?
Give example of mountains formed by destructive plate boundaries
Fold mountains, volcanoes, earthquakes and possibly tsunamis (Nazca plate)
The Andes are an example of these mountains
The Andes
Give the two types of natural hazards. Define them. [4 marks]
- Geologic/ tectonic:
Hazards that are caused by the movement of tectonic plates. - Atmospheric/ metrological:
Hazards that are caused by the weather and climate
Give examples of geologic/ tectonic hazards [3 marks]
- Earthquakes
- Volcanoes
- Tsunamis
Give examples of metrological/ atmospheric hazards [3 marks]
- Tropical storms
- Drought
- Flooding
What is the definition of a ‘hazard risk’?
It is the proabability that a natural hazard will occur
What are 3 factors affecting hazard risk?
- Vunerability
- Capacity to cope
- Nature of natural hazards
What are the layers of the eath?
- Inner core
- Outer core
- Mantle
- Crust
What are the different types of plate boundaries?
- Constructive
- Destructive
- Conservative
- Collision
What is the evidence for continental drift? [4 marks]
- South America and West Africa fit together like a puzzle
-
Fossil correlation- Mesasaurus was found in Africa and S America even though it can’t go in salt water.
Also, there is similar rocks and fossil plants. - Glacial striations- Scratches from glaciers were found in the Amazon rainforest
- Ural mountains, apls and rockies hve a rock correlation and join together.
What does paleoclimate data refer to?
Prehistoric or very old data about the climate
What is continental drift?
Why does it happen?
1) The gradual movement of plates/ continents across the earth’s surface.
2) It happens due to convection currents
What are convection currents?
When the hot magma in the eath rises, reaches the crust (where it can’t rise anymore) cools, and goes back down. This, over time, forces the crust appart and together.
Define ‘magnitude’
The overall strength of the earthquake
Define ‘Richter scale’
The scale used to measure the magnitude of an earthquake
Define ‘effects’ in terms of earthquakes
The impacts created by an earthquake
Define ‘responses’ in terms of earthquakes
How different groups respond to an earthquake
What is the typical time gap for immediate responses?
hours-days
What is the typical time gap for long-term responses?
weeks-months
Is this an immediate or long-term response:
Evacuating people
Immediate
Is this an immediate or long-term response:
Repair of homes and rehousing people whose homes were destroyed
Long-Term
Is this an immediate or long-term response:
Providing food, water and shelter
Immediate
Is this an immediate or long-term response:
Improve building regulations so buildings can withstand future hazards
Long-Term
Is this an immediate or long-term response:
Charities sending aid workers or supplies
Immediate
How can you predict a volcanic eruption? [6 marks]
- Seismograph vibrations
- Infared imagery
- More gas (sulphur) in the air
- Strange animal behaviour
- Shape of volcano changes (rock deformation)
- Some people living close to the volcano may have brown, contaminated water
How can you prepare for an earthquake? [4 marks]
- Earthquake proof buildings
- Drills and education
- Alert system
- Having a food/ water/ medication stash
How many seconds of notice may you have before the earthquake starts?
13 seconds
Why musn’t you have a naked flame during an earthquake?
The gas pipes may be damaged, leading to a gas leak. A naked flame will spread very fast in a gas leak.
How can earthquakes be predicted?
They can’t be precisley predicted like eruptions, as they have a lack of clear warning signs. However, scientists can look back at historical records and make an approximate prediction.
How to scientists monitor volcanos? [6 marks]
- Remote sensing: Satellites detect heat and shape deformation of the volcano
- Seismicity: Seismographs record earthquakes
- Ground deformation: Changes to the shape of the volcano are measured using laster beams
- Geophysical measurements: detect changes in gravity as magma rises to the surface
- Gas: Gases that are released when the magma rises are detected
- Hydrology: measurments of gases dissolved in water
Give examples of earthquake proof buildings [2 marks]
- Transamerica building in San Francisco
- Tokyo Sky Tree
What do earthquake proof buildings have underneath them?
Rubber shock- absorbers
These will absorb most of the vibrations and minimise the amound of force exerted on the building.
Complete this sentence on earthquake proof buildings:
Sometimes builders will make sure the building is placed on suitable ___ that will withstand the eathquake.
Bedrock
What do buildings have to make them earthquake proof? [8 marks]
- Underground rubber shock- absorbers
- They are placed on bedrock for stability
- Built from fire-resistant materials
- Automatic window shutters to stop glass from falling on people
- Flexible outer panels
- Frames made of steel and are interlocking for support
- Computer controlled weights on the top of the building to reduce movement of the building
- They have space for open areas where people can evacuate
What happened in Kobe in 1995 earthquake?
Gas pipes started to burst
