G The Restless Earth Flashcards
Describe the distribution of earthquakes. (3)
earthquakes occur in linear clusters many occur on plate boundaries especially destructive and/or conservative plate boundaries Clustering around edge of Pacific plate
Explain why earthquakes occur at conservative plate boundaries. (4)
Plates moving in similar directions or same direction, but at different speeds
the pressure build up as the plates stick
the sudden release causing the jerking movement which is the earthquake.
Eg San Andreas Fault.
Explain why the damage was limited. (1)
Epicentre in a rural area/field so damage less than if it had been in a built up area.
Use a case study to describe the responses to a tsunami. (8)
Over 100 000 Japanese soldiers deployed in search and rescue, distribute blankets, food, water.
Specialist teams from overseas.
Exclusion zone around nuclear plant and evacuation.
Re building reconstruction programme, involve houses, infrastructure and communication systems, port facilities rebuilt.
Defence extended above standard 12m.
Give two differences between continental crust and oceanic crust. (2)
Continental crust is lighter than oceanic crust/less dense
continental is older than oceanic crust
continental crust cannot be renewed and/or destroyed Continental crust is thicker.
Characteristics of volcano (3)
crater rim of crater, steep sides cone shape ash/loose material on sides ridges on sides.
Explain how volcanoes form at constructive plate margins. (4)
Plates move away from each other (3cm/year)
CC in mantle.
As they pull apart, cracks and fractures where no crust. This is filled by magma rising up out of the mantle to plug the gap and make the crust complete.
As this occurs again and again, layers of lava solidify and build up to create volcanoes.
This often happens under the oceans.
Describe the size and shape of a supervolcano (2)
mega (colossal) eruption where at least 1000 cubic km of material is erupted
Caldera, tend to be sunken surrounded by area of higher land.
Flat areas
Describe the likely worldwide effects of a supervolcano eruption. (6)
87000 predicted deaths
large ash cloud rising 40 – 50km into atmosphere, destruction of 10000 square km of land
ash 15cm thick covering buildings collapse within 1000km
The UK would see the arrival of the ash 5 days after the eruption
temperatures would fall between 12 and 15 degrees. Parts of Europe and America and Asia would see constant snow cover for 3 years
crops would fail, monsoon rains would fall, flights suspended, livestock choke on ash and farmland affected.
40% of population could face starvation.
One in three people will be killed within 1000km of an eruption.
Describe how people use fold mountains. (8)
Use a case study to describe how people use fold mountains (6)
In Bolivia, many subsistence farmers grow a variety of crops on the steep slopes, including potatoes.
Terraces to create areas of flat land on the slopes
Llamas have historically been used a lot in the Andes; male llamas are used as pack animals whilst the females are used for meat and their wool is used for clothes.
Since the Andes are rich in materials such as tin, nickel, silver and gold, much mining happens here.
The largest mine in the world is situated in Peru and is called the Yanacocha gold mine. As a result, it has led to the expansion of a nearby town of Cajamarca from 30,000 to 240,000 inhabitants in 2005, as wells as more jobs.
Due to the steep and narrow nature of fold mountains, it is advantageous to build HEP stations.
For example, the Yuncan project dams the Paucartambo and Huachon rivers in north east Peru.
These high fold mountains provide spectacular scenery of lakes and glaciers. T
he Inca Trail is a 45km trek and ends in the historic settlement of Machu Picchu, where over 250 species of orchid exists, therefore attracting many tourists.
Describe the location of ocean trenches. (2)
Often ocean trenches seem to be near to fold mountains Ocean trenches occur most on the edge of the Pacific Ocean. Here they almost circle it, except
for the west coast of North America.
There are small ocean trenches in the Caribbean.
Explain the formation of young fold mountains and ocean trenches. (8)
Rivers erode material from land surface and transport it to sea.
Sediment is deposited on ocean floor, layers build up over time forming sedimentary rock due to compression. Plates move together, at destructive/collision boundary. Rocks crumple as a result, forming fold mountains, large ranges of mountains where different rock layers have crumpled into anticlines and synclines.
Also form at subduction zones where the continental crust crumples as it meets the oceanic crust.
Destructive/subduction, the oceanic subduct below the continental.
At this point, the sea is very deep and it is here that there are ocean trenches, long narrow steep sided depression of oceanic.
Outline how the Richter scale is used to measure earthquakes. (3)
Richter Scale uses information collected by seismometers that record the strength of shock waves and amount of movement
A seismogram is produced showing a ‘line graph’ of the waves
This is used to assign a
number on the Richter Scale between 0/1 and notionally 10 (but there is no upper limit)
The scale is logarithmic so that an increase of 1 represents a 10 fold increase and of 2 a hundred times etc .
What is the difference between the focus and the epicentre of an earthquake? (2)
Focus is within the earth’s crust - where the earthquake begins
epicentre is the point on the Earth’s surface directly above the focus.
Compare and/or contrast the characteristics of the two earthquakes. (4)
Figure 2 shows the depth of the focus to be similar – approx 9 – 13 km below the surface. This is relatively shallow. The magnitude was different, the Haiti one
being 0.7 stronger – 7.0 as opposed to 6.3 and so was more powerful – about 7 times. The Haiti earthquake affected much of the country – mainly in the south.
Less of Italy was affected – a central area east of Rome. The shock waves seem to cover a wider area in Haiti, suggesting greater impact.
