Download Tectonicspastexamquestions 143.55KB 2017-03

Tectonics
•
To review key themes from the tectonics unit.
•
To link ideas from across the unit to answer exam
questions.
Exam question
Outline how the type of magma effects the
shape of extrusive landforms. 7 marks
 Why is it more hazardous to live near destructive
margins than constructive ones? (7)
 This is about impacts on humans but also requires knowledge of
processes taking place at the respective margins. Comments regarding
different human perspectives are also relevant.
 Constructive margins have relatively small land surfaces and so fewer
people are directly involved. The processes of sea floor spreading and the
development of (largely submarine) volcanic ridges are fairly gentle affairs
and, even when hazardous, can be managed (Heimaey, Iceland 1973).
 Destructive margins have far more violent processes with explosive, more
acidic volcanoes. Since many destructive margins are near coasts there
are likely to be more people living there and so are also subjected to
earthquakes and tsunamis.
 It is unlikely that candidates will attempt to argue against the statement
but any attempt to do so should be assessed in the light of the levels
criteria.
 Level 1 – Generic Descriptor (1 - 3)
 Basic statements, with general differences or reference to only one
type of
 margin.
 Level 2 – Generic Descriptor (4 - 6)
 More detailed comments about both types of margins and
understanding
 of either theory or impacts, probably with exemplars.
 Level 3 – Generic Descriptor (7)
 Detailed and knowledgeable comments regarding both margins with
an
 explanation showing understanding of both theory and impact, with
 exemplars.
 Total for this question: 15 marks
 Study Figure 2 which is a diagrammatic section through
part of the earth’s crust.
 Figure 2
 (a) Distinguish between intrusive and extrusive volcanic
activity.
 Outline the differences between the intrusive features
shown in Figure 2.
 Intrusive activity takes place beneath the earth.s surface through
magma, which cools slowly within the crust, forming large
crystals, usually granitic rock, often cracked by large joints and
makes up the larger proportion of the earth.s crust.
 Extrusive activity takes place on the earth.s surface through lava,
which cools quickly in air or water, forming small crystals, usually
basaltic or andesitic rock and makes up the smaller proportion of
the earth.s crust.
 Each mark is awarded for distinguishing between different
features. This can be done by comparison (intrusive activity takes
place beneath the earth.s surface, whereas extrusiveactivity takes
place on the surface) or comparative (intrusive magma cools
slower than extrusive lava) or juxtaposition (as in the 2
paragraphs above). Since part (b) refers specifically to features,
there is no credit here for them. (4 marks)
 Describe the distribution of the earthquakes and
attempt to explain the
 pattern that is shown.
 Level 1 Basic/simple statements with regard to
distribution, mainly names of countries or areas affected
by earthquakes. Explanation confined to plate
boundaries. (1–4 marks)
 Level 2 Wider picture seen, such as the ‘Pacific Ring of
Fire’. Some reference to the large areas where there are
or few recorded instances. More details on plate
boundaries such as the activity taking place there which
results in earthquakes and activity within fold
mountains. Some attempt to explain why some areas
are free/relatively free from earthquakes. (5–7 marks).
 As this question is levels marked, you will receive
only Level 1 marks if you describe the distribution in
piecemeal form, i.e. simply a list of countries/areas.
You must describe a wider pattern to reach Level 2.
Similarly, explanations must go deeper than simply
stating that the earthquakes are on or near plate
boundaries. You could state what is happening to
cause earthquakes at specific boundaries (must be
those shown on the map, not earthquakes in
general) such as on the conservative margin in
California.
 b Describe the effects that a major
earthquake can have on the
population
 of an area. (8 marks)
 Level 1 Simple statements giving nothing more than a
list of the effects. (1–4 marks)
 Level 2 Recognises that effects can be divided into
primary and secondary and gives examples of each
(accept candidate’s own definition of primary/secondary
as long as it is logical). Links are clearly made between
primary and secondary hazards, e.g. ground shaking can
cause buildings to fall. breaking gas pipes which could
lead to fires breaking out. Several effects can be linked
together in a chain; another example could be ground
shaking resulting in dams cracking, collapsing and
leading to flooding downstream. (5–8 marks).
 To reach the higher mark level, you must do more than
write a list of effects. With many hazards it is important
to recognise that there are both primary effects and
later secondary effects, which may last for a
considerable period of time after the event. It is also
essential to see that one effect may be the cause of
another. If you can link the hazards in this way, your
mark will be at the top of the range.
 Discuss the ways in which people and organisations
respond to earthquakes and their effects. (10 marks)
 In general, they may include:
 • in inability to leave area, or reluctance preparation in the event of
earthquakes - FEMA (USA)
 • modification of buildings - variety of ways could be described
 • education to minimise loss of life, including earthquake drills,
emergency supplies in the
 home, posters
 • fire prevention - smart meters
 • pre-planning of emergency services
 • land-use planning to minimise damage and risk.
 Mark scheme
 Level 1 – Simple statements of responses which could apply to any
earthquake hazard.
 No specific detail provided. 1-3 marks
 Level 2 - Specific statements of responses which can be clearly attributed
to named areas and/or earthquakes access this level. 4-8 marks
 Level 3 - Fully developed answer, with good elaboration of more than one
response.
 Rounded answer with full range of responses analysed and/or evaluated.
 9-10 marks
 (c) With reference to examples, discuss the effectiveness
of hazard management
 schemes in areas where earthquakes have taken place.
(10 marks)
 Level 1 (1–4 marks)
 Identifies several methods of management, but only at a superficial
 level. Loosely ties management techniques to specific events or
 areas. Examples used are very thinly developed. Material on
 effectiveness of schemes is little more than they work or do not work.
 Level 2 (5–8 marks)
 Clear identification of schemes and areas in which they are used.
 Shows, with some details, how effective such schemes can be and
 why they work Good use of exemplar material.
 Level 3 (9–10 marks)
 Clearly links the schemes, the areas in which they operate to their
 effectiveness in particular situation. Answer contains very good use of
 exemplar material, with some background to the events and the
 effectiveness of particular schemes at the time of the event.
 Figure 1
 (Earthquake intensity and number of deaths from 10
earthquakes since 1985)
 (a) Comment on the information given in Figure 1. (7
marks)

Level 1 (1–4 marks)

Simple statements as to death toll and size showing some elements of

correlation. Some slight indication that the correlation is not strong.

Some basic attempts at commentary but with little idea why the

correlation not entirely clear.

Level 2 (5–7 marks)

Shows a clear idea of the strength of the correlation (or lack of it) and

offers evidence, particularly in terms of highest size (Mexico City)

having lower toll and that of Iran with lower size but high toll. Indicates

that size is not the only factor in toll, with evidence from the

information given, particularly comparing those events with similar

size, i.e. Gujarat, Taiwan and Turkey.
Odd one out
 Batholith – laccolith – fumarole
 Composite – acid/dome – caldera
 Oceanic/oceanic – oceanic continental –
continental/continental.
 Dyke – sill – laccolith