Restless Earth Flashcards
What is the physical state of the Continental Continental and oceanic crust
Solid
Describe the structure of the earth from the outside to the inside
Crust Asthenosphere Mantle Outer core Inner core
What is the physical state of the asthenosphere in the mantle?
It is partially Molten
What is the physical state of the mantle
Solid
Describe the density and physical state of the outer core
The outer core is in a liquid physical state and it is very dense
Describe the density and physical state of the inner core
the inner core is in a solid physical state and it is very dense
What is Continental crust composed of
Granite
What is Oceanic crust composed of?
Basalt
What is the asthenosphere composed of?
Peridotites
What is the mantle composed of?
Silica based minerals
What is the outer core composed of?
Iron and nickel
What is the inner core composed of?
Iron and nickel
What is the temperature of the Continental?
Up to 900 degrees Celsius
What is the temperature of the Oceanic crust?
Up to 900 degrees Celsius
What is the temperature of the Mantle?
1600-4000 degrees Celsius
What is the temperature of the Asthenosphere ?
1000-1600 degrees Celsius
What is the temperature of the Outer core?
4000-5000 degrees Celsius
What is the temperature of the inner core?
4000 -5000 degrees Celsius
How thick is the oceanic crust
6-8 km
How thick is the Continental crust
25-80km
What are the differences between oceanic and continental crust (3 marks)
- Oceanic crust is thinner than Continental crossed as oceanic crossed is 6 to 8 km thick but Continental crust is from 25 to 80 km thick
- Oceanic crust is denser than Continental crust
- oceanic crust is composed of basalt, contrastingly the Continental crust is made up of Granite
What causes the high temperatures in the earth’s core?
Gradual Radioactive decay
What are the effects of the movement of the convection currents?
Convection current can cause movements in the crust and and can also cause hotspots
What are convection current’s
Convection currents are currents of molten rock that move within the mantle which creates movement in the Crust
Names the three plate boundaries
Conservative margins
constructive margins
and destructive margins
How are constructive margins formed?
Constructive margins are formed when magma rises and splits up Continental Crust which forces the plates apart
What tectonic event is likely to be found or occur at a constructive plate boundary
Submarine volcanoes
Given example of where there is a constructive plate boundary
The Eurasian plate is separating from the north American plate
If the plates on the constructive plate boundary were arrows what would they look like
⬅️➡️
How are destructive margins formed?
When oceanic plates collide with continental plates the denser oceanic plate sinks in underneath the continental plate this is called subduction
What Tectonic events are likely to occur at a destructive plate boundary?
Volcanoes
Fold mountains
Earthquakes
Give an example of plates that are in a destructive plate boundary
Nazca plate and South American plate
If destructive plate boundaries were arrows what would they look like
Two arrows pushing together and then one sinking under the other
How are Conservative plate boundaries formed?
Conservative plate margins are formed when plates slide past each other and the friction between the two plates and stress between the two plates builds up
What tectonic event is likely to occur at the Conservative margin
Earthquakes
Give an example of where a Conservative margin can be found
Between The North American plate and Pacific plate
If the Conservative margins were arrows what would they look like
⬆️⬆️
What factors affect where volcanoes and earthquakes occur?
They are most likely to occur on plate margins
Volcanoes can also occur on hot spot
What are hot spots?
They are the areas of rising magma in the Asthenospere that creates volcanoes
What are the two types of volcanoes
Composite
Shield
What is the lava that flows from a shield volcano like?
It is basaltic magma, it flows quickly and is fluid
What is the magma that flows from a composite volcano like?
It’s granitic magma, is sticky and flows very slowly.
How often to shield volcanoes erupt and what are the eruptions like?
Very frequent- gentle eruptions
How often do composite volcanoes erupt?
They’re infrequent and unpredictable. The pressure builds up over time
Give an example of a shield volcano
Mauna Loa (Hawaii, USA)
Give an example of a composite volcano
Mt Pinatubo ( Philippines ) Mt Sakurajima (Japan)
State two impacts of volcanoes on settlements
Ash cloud deposition Transport links disrupted Flooding Water contamination Health issues
Describe how convection currents cause plate movements
Magma from the mantle
is heated by radioactive decay
the high temperatures cause the Magma to rise this is called a convection current
the convection currents push and pull on the plates causing them to move
Explain how hazard resistant design can reduce the impact of earthquakes in the developing world
Wall corners could be strengthened with wire mesh and cement. This prevents walls collapsing from earthquakes ,protecting people and property
The weight of roofs can be reduced with lightweight materials used. This means If an earthquake occurred the building would be less damaged if the roof was collapsed and it’d be less likely a resident would be crushed under the pressure
Especially in central business districts like Mumbai, buildings are dug with deep foundations which makes the building more sturdy and less likely to collapse in the event of an earthquake.
Describe how convection current’s cause plate movements
Magma from within the mantle ,is heated by radioactive decay ,the Magmar circulates in huge convection currents, the magma rises , and pushes against the plates of the crust causing them to move
Why is it more like for an earthquake to occur between the North American plate and Pacific plate and not a volcano (4)
Because the Pacific plate and North American plate are on a Conservative margin (meaning these plates are sliding past each other ) there is no subduction or Magma so no plate is being created or destroyed therefore and volcano would not occur however there is friction between the plates and stress builds up, eventually the stress is released and an earthquake occurs
What causes the earth’s magnetic field
Minerals including iron that rise and fall in the liquid outer core
What factors affect the impact of a hazard?
- The size of the event
- the vunerability of the population e.g. poverty
- the preparedness of the population
- The quality of emergency services
- The time of day (night time is better as there are less people out)
- Depth (shallower the more destructive)
- the distance from the epicentre
What is a tsunami ?
A series of destructive oceanic waves which can be cause by earthquakes and large volcanic eruptions
What causes tsunamis ?
When the seabed is displaced (this can be caused by Sub- Sea earthquakes ) the waves travel across oceans at speeds up to 900 km/h
Give a case study of a tsunami
The Indian Ocean tsunami on 26 December in 2004 killed over 250,000 people in 14 countries
Describe two characteristics of a TSunami wave
When they strike land waves can be 20 to 30 m high and flood the land
they travel across Oceans at speeds up to 900 km/h
Describe the differences between composite and shield volcanoes
Compositw volcanoes are steep sided
and cover a small area.
They have layers of ash and lava .
Shield volcanoes have gentle slopes and cover a large area
they are almost all Lava
Investigate their primary and secondary impacts of earthquakes in an LEDC
Port- au-Prince, Haiti
January 2010
Magnitude 13km
Struck at 5pm
Primary: 316,000 deaths and 300,000 injured. Economic loss of £8.5 billion
Secondary: Over 7000 people died in aftershock. 1 million people wear made homeless. Damage to road stopped trade. Cholera spread from lack of sanitation and clean water
Investigate the primary and secondary impacts of earthquakes in a MEDC
Canterbury, New Zealand
September 2010
Magnitude: 7.1
Depth: 10 km.
Time:4.30 am
Primary: no deaths about 100 injuries damage to property they to came to about £1.8 billion deaths were no as in most people were asleep and buildings had strong structures
Secondary: A huge after-shock with a magnitude 6.3 occurred in February 2011 and near by Christ Church which killed 185 people
What are the differences between primary and secondary impacts of an earthquake?
Primary Impacts- The immediate effect of an earthquake on property and people.E.g deaths injuries or buildings collapsing (property destruction)
Secondary Impacts- The impact on property and people of an event after it has finished e.g. homelessness, the lack of resources ,fires ,the reduction of trade ,disease and after-shocks
What is an extinct volcano?
A volcano that is not expected to arupt again
Investigate the primary, secondary , economic and social impacts of a named volcanic event
Mount Merapi, Indonesia (composite)
Primary-360,000 people evacuated from the area
Social-275 killed mostly burned by the hot ash and gas in pyroclastic flows
Impacts-570 Injured
P.Economic- Several villages destroyed and crops were damaged from ash fall
About 2000 animals were killed. Many flights in the area were cancelled due to the ash cloud.
Secondary Social- an area 10 km around the volcano was declared a danger zone and 2600 people were not able to return to it.
Thousands of people spent two weeks living in cramped emergency centres
Secondary Economic -1300 hectares of farmland were abandoned
-economic loss of $600 million due to severely reduced to farming and tourism income
What tectonic hazards can be predicted?
Volcanic eruptions
Tsunami
How are volcanoe eruptions predicted
Bulging of a volcano is flanks can be used to predict eruptions
or gas emissions and earth tremors can give a sign that a volcano may erupt
Give an example of when predicting a tectonic event has been useful
In 1991 about 120,000 people were evacuated from the area around Mount pinatubo in the Philippines before it erupted
How are people warned of a tsunami to come?
Tsunami warning sirens can be used to evacuate people from coasts before the tsunami waves strike
Examine the role of prediction, warning and evacuation concerning earthquakes
Earthquakes cannot be predicted however people can be made prepared from emergency plan and well trained and funded emergency services warning systems and evacuation routes.
The impact (mitigation ) of hazards such as this can be reduced by hazard resistant buildings , disaster kits and landuse planning.
How can hazard resistant design reduce the impact of earthquakes in the developed world
Wall corners could be strengthened with wire mesh and cement to prevent them collapsing and hurting residences
The weight of roofs could be reduced by removing the mud overlay, this would prevent the roof collapsing and if it were to collapse it would have a less chance of hurting residences
Light weight hollow bricks could be used
The buildings must be built with the deep foundations to stable bedrock
Look absorbers built into frames and foundations this makes the building strong enough and flexible enough to absorb the energy of an earthquake
Double glazed Windows to reduce the glass breakage
Outline how buildings would be built to be hazard resistant in developing countries
The weight of roofs could be reduced
Wall cornered strengthen with wire mesh and cement
Hollow bricks used
Deep foundations attached to the building to stable bedrock
Shock absorbers built into the frames
How can hazard resistant design reduce the impact of earthquakes in the developing world?
Shock absorbers built into frame and foundations, base isolators absorb some of the sideways motion from earthquakes that would otherwise damage the building
Buildings can be built with double glazed windows to reduce glass breakage
The weight of roofs can be reduced by removing the mud overlay on , to reduce likeliness of roof collapsing and if it were to collapse residents are less likely to be damaged
Light weight hollow bricks used
Wall corners can be strengthened with wire mesh and a cement overlay, which reduces the chances of the wall collapsing and if the wall was to collapse it is less likely that the residents would be hurt
What was the response to the Haiti earthquake in January 2010?
Port-au-Prince, Haiti
Magnitude:7.0
3 million people needed emergency aid
The red cross dispatched a relief team the U.N.’s world food program flew in two plains with emergency food aid.
World vision an NGO provided emergency shelter for 41,000 families and delivered 16,000,000 L of clean water. They also installed 300 showers and 240 toilets
How effective was the response to the Haiti earthquake in January 2010?
The country is controlled by a corrupt government that may not give aid to the right people
even in 2012 haiti are still trying to recover from the 2010 earthquake
Many women were badly affected and forced into prostitution
What is an NGO
It stands for Non-Governmental Organization, they are neither run by the government nor a conventional for profit firm .
