Section 5 The unstable earth
Fundamental exercise
Unit 1 Earthquakes, volcanic eruptions and plate movements
Fill in the blanks
1. Fill in the blanks below with the appropriate words.
(a) The Earth is divided into 3 parts: the __core__, the mantle and the crust. Among them, the __crust__ is the thinnest layer.
(b) There are two kinds of plates: the __continental__ plates and the __oceanic__ plates.
(c) Plates are pulled apart or pushed together by the __convective currents__ in the mantle.
(d) The world’s major earthquake and volcanic zones include the Alpine-Himalayan belt and the __Circum-Pacific Ring of Fire__.
(e) The point where energy and seismic waves are release in an earthquake is called the __focus__.
2. Write down the name of the plates on the diagram below and use arrows to indicate the directions of plate movements.
Unit 2 What are the effects of earthquakes and volcanic eruptions?
Fill in the blanks
What kinds of hazard do earthquakes and volcanic eruptions bring? Complete the diagram below by filling in the blanks.
Unit 3 Human responses to earthquakes and volcanic eruptions
Fill in the blanks
Why do people still live in the unstable areas? What do they do to reduce the impacts of earthquakes and volcanic eruptions? Fill in the blanks below with the appropriate words.
Minimizing the impacts of earthquakes and volcanic eruptions
Integrated exercise
Multiple choice
1. Choose the correct answers to the questions below.
(a) Which of the following descriptions about the Earth’s crust is not true? (refer to Unit 1)
A. It is the outermost layer.
B. It has the lowest density.
C. It has a thickness of 2 900 km.
D. It consists of the continental plates and oceanic plates.
(b) Which of the following diagrams does not show correct plate movement? (refer to Unit 1)
A. C.
B. D.
(c) What are the materials that may come out of a volcano during an eruption? (refer to Unit 1)
(i) Lava (iii) Ashes
(ii) Poisonous gases (iv) Volcanic bombs
A. (i) and (ii) C. (ii), (iii) and (iv)
B. (i), (ii) and (iii) D. All of the above
(d) Part X in the figure below is known as the (refer to Unit 1)
(e) “Since the plate X is constantly pushing toward the South American Plate, Chile is therefore suffering from earthquake hazards from time to time.” What is the plate X? (refer to Unit 1)
A. Philippine Plate C. Pacific Plate
B. Caribbean Plate D. Nazca Plate
(f) If the horizontal scale and vertical scale of a cross-section are 1:20 000 and 1:10 000 respectively, what is the vertical exaggeration? (refer to Unit 1)
A. 4 C. 0.5
B. 2 D. 0.1
(g) Which of the following is not a disastrous effect of volcanic eruptions? (refer to Unit 2)
A. Mudflows C. Lava flows
B. Bush fires D. Tsunamis
(h) Which of the following does not help reduce the number of deaths in an earthquake? (refer to Unit 3)
A. Insurance schemes C. Temporary shelters
B. Clean water supply D. Putting out fires
(i) What benefits do volcanoes bring to people? (refer to Unit 3)
(i) Geothermal energy (iii) Scenic attractions
(ii) Rich mineral deposits (iv) Irrigation
A. (i), (ii) and (iii) C. (i), (iii) and (iv)
B. (i), (ii) and (iv) D. All of the above
(j) Which of the following help reduce the impacts of earthquake hazards? (refer to Unit 3)
A. Shock-proof building designs C. Regular earthquake drills
B. Forecasting and warning systems D. All of the above
Geographical concepts
2. There is a mistake in each of the following statements. Underline the mistake and write the correct answer in the space provided below.
Short questions
3. An earthquake measuring 7.6 on the Richter scale at the epicentre occurred in central Taiwan on September 21, 1999. The map below shows the maximum magnitude of the earthquake recorded at different locations in Taiwan. Next to the map is an advertisement to attract people to visit Taiwan. Study them carefully and answer the following questions.
(a) Label the plates on the map.
(b) Describe how the maximum magnitude of the earthquake changed with the distance from the epicentre in general.
The maximum magnitude decreases with increasing distance from the epicentre in general.______
(c) Why are there many hot springs in Taiwan?
Taiwan lies on a plate boundary where volcanic activities are present. Underground water is heated up by magma beneath/near Taiwan and hot springs are formed.______
(d) Do you like to visit Taiwan? Why or why not?
Free response______
______
______
Advanced questions
1. Earthquake disaster
Study the table below and complete the tasks that follow.
The 10 deadliest earthquakes of the 1990s
(a) Mark and label the above earthquakes (A-J) on the world map below.
(b) Which of the earthquakes took place on the Circum-Pacific Belt? Which of them happened on the Alpine-Himalayan Belt?
(c) Decide whether each of the following statements is true or false.
(i) Earthquakes of greater magnitude (in Richter’s scale) cost more True/False
deaths.
(ii) Earthquakes in less developed countries cost fewer deaths. True/False
(iii) Earthquakes that occurred in early 1990s cost fewer deaths. True/False
(d) List some factors that may affect the number of deaths in an earthquake?
Population density, time of occurrence, quality of buildings and others______
______
2. Exploring a volcano
Study the map below which shows a volcano and its surrounding area.
(a) Draw a cross-section along line X-Y.
(b) What is the vertical exaggeration of your cross-section?
Horizontal scale = 1:50 000______
Vertical scale = 1:25 000______
Vertical exaggeration = Vertical scale/Horizontal scale = 2______
______
(c) How do people make use of the rich resources in this volcanic area?
- Development of farming (fertile soil)______
- Generation of cheap electricity (geothermal power)______
- Development of tourism (scenic beauty)______
______
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