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SAMPLE PAPER
2
Level 2 Earth and Space Science
2.5: Demonstrate understanding of the causes of extreme
Earth events in New Zealand.
Credits: Four
Check that you have completed ALL parts of the box at the top of this page.
You should answer ALL parts of ALL questions in this booklet.
If you need more space for any answer, use the page(s) provided at the back of this booklet and clearly
number the question.
Check that this booklet has pages 2–9 in the correct order and that none of these pages is blank.
YOU MUST HAND THIS BOOKLET TO YOUR TEACHER AT THE END OF THE ALLOTTED TIME.
EXEMPLAR FOR EXCELLENCE
NOTE: These exemplars do not fully show Grade Score Marking (GSM) because of
the small sample of student scripts involved, and the absence of a cut score meeting
to determine grade boundaries. In 2012, level 1 2011 examination papers will have
exemplars marked fully in accordance with GSM. These will be published on the
NZQA website when the assessment schedules are published.
This exemplar has been generated by a subject expert not a candidate.
© New Zealand Qualifications Authority, 2011
All rights reserved. No part of this publication may be reproduced by any means without the prior permission of the New Zealand Qualifications Authority.
2
You are advised to spend 60 minutes answering the questions in this booklet.
QUESTION ONE: VOLCANIC ERUPTIONS
Mt Ruapehu is a stratovolcano, mostly andesitic in nature, found in New Zealand’s
Taupo Volcanic Zone. The last time Mt Ruapehu erupted was in 1996. It is a typical
andesitic volcano with a classic cone shape.
Explain why Mt Ruapehu erupts andesite and discuss the characteristics of such an eruption. In
your answer, you should:
•
state why active volcanoes occur in New Zealand’s Taupo Volcanic Zone (TVZ)
•
outline the tectonic plate processes under New Zealand’s North Island
•
use plate tectonics to explain what causes Mt Ruapehu to erupt andesite (you may use and label
the diagram in the box below to support your answer).
The intermediate grade magma underneath Mt Ruapehu has water mixed in it (from the
ocean), because it is under pressure it remains water under ground. As the lava erupts from
the volcano the release in pressure causes the water to turn to a gas (steam) making the
eruption explosive. This means the lava and ash from the eruption explodes out of the
volcano and the reason why andesitic lava is explosive.
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Andesitic magma occurs when the continental crust, which is silica rich, melts and mixes
with the Gasaltic oceanic crust in a subduction zone. This creates a intermediate grade
sticky magma called andesite.
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QUESTION TWO: COOK STRAIT CANYON
The Wairarapa earthquake of 1855 measured 8.2 on the Richter Scale and originated on
the Wairarapa fault. This earthquake caused the coastline around Wellington to be
significantly uplifted.
Source: Underwater Canyon, image used with the permission of National Institute of Water and Atmospheric Research (NIWA)
Despite the epicentre of the quake being under land a tsunami was observed in Cook
Strait and Wellington Harbour.
Explain, using plate tectonics, the cause of the Wairarapa earthquake and how this resulted in a
tsunami in Cook Strait and Wellington Harbour. In your answer, you should:
• explain what caused the Wairarapa earthquake
• use evidence from the diagram to explain how a land based earthquake lead to a tsunami the
Cook Strait and Wellington Harbour.
You may draw a labelled diagram(s) in the box provided to support your answer.
The Wellington region has two plates (the Australian and Pacific) meeting in a zone of
lateral movement. This means that both plates are pushing against each other, which
causes a converging plate boundary in the region.
However, it is not simple as the Australian plate moving northwards while
the Pacific plate moves southward. In reality, the Wellington Region has a convergent
plate boundary that is also a transform fault. The two plates are locked together (both
pushing towards each other) and are also trying to move past each other.
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This means that there is considerable stress at this plate boundary and Wellington
commonly has earthquakes to release the pressure built up from the plate movement.
In 1855, the Wairarapa Earthquake released a great deal of energy from this plate boundary
that resulted in a large Earthquake centred in the Wairarapa well away from the sea. It
caused a Tsunami because the energy from the quake was released in waves, which
shocked the region. The Cook Strait Canyon is a steep sided deep trench that was also
shaken by the quake. This energy transference caused the sides of the canyon to subside
and result in an undersea landslide; displacing a huge amount of water and transferring
lots of energy to the water.
In deep water in the Cook Strait, the wave was very small but as the wave moved to shallow
water, near the coast line of Wellington Harbour and region (plus north of South Island), the
huge energy of the wave meant that the size of the wave dramatically increased and a
tsunami (caused by an undersea landslide) was seen in the area in the hours after the
earthquake.
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QUESTION THREE: CHRISTCHURCH EARTHQUAKE OF 4TH SEPTEMBER 2010
In the early hours of September 4th 2010 Christchurch was rocked by a magnitude 7.1
quake that caused liquefaction that lead to major damage to Christchurch city and its
surrounding districts. Christchurch city is located on alluvial plains that were formed
from ancient sediments from the Southern Alps. The plains are crossed by multiple
rivers and streams.
Discuss, with reasons, the causes of the magnitude 7.1 Christchurch earthquake and explain why
this earthquake caused liquefaction of land in many areas of the city. In your answer, you should:
• explain the type of tectonic plate boundary in the South Island
• explain how the South Island’s tectonic plate boundary leads to earthquakes
• define liquefaction and describe its effects on land
• explain in detail the characteristics of land that is prone to liquefaction.
You may draw a labelled diagram(s) in the box provided to support your answer.
The plate boundary in the South Island is a convergent plate boundary because the
Australasian and Pacific plate are both continental and have the same density. This has
resulted in the South Island’s Southern Alps and the formation of the massive
transformation fault – the Alpine fault. This fault can be considered as plate boundary of the
Australasian and Pacific plates. Plates converging and moving laterally past each other is
not a smooth process and at times they get stuck and movement stops until energy is
released via an earthquake. The plates move relative to one another.
In the South Island, this release of pressure does not just result in movement of the Alpine
fault, there are other fault lines that move. Lots of fault lines are hidden because they are
covered by sediments. This was the case in the 4 September earthquake as the East West
previously unknown fault line called the Green Dale Fault moved significantly to release
energy. This earthquake was very shallow so shaking was severe at the Earth’s surface.
To compound this problem, Christchurch is built on old sediments that originate from
Toulesse rocks of the Southern Alps. These sediments are different sizes and the shaking
sorts them by size with the smallest (eg, sand) at the top and largest (eg, gravel) at the
bottom. This is called liquefaction.
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Liquefaction is most severe when you have water mixed in with
sediments. When this mixture (water and sediments) is shaken you get the solid soil
turning into a mush slurry with sand sized particles at the top and bigger particles below.
So, if your house is near a river or a wet area in Christchurch you would have had more
liquefaction than if the soil (sediments) was dry like in other areas.
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Extra paper for continuing your answers, if required.
Clearly number the question.
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Extra paper for continuing your answers, if required.
Clearly number the question.
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