READING PASSAGE 3
You should spend about 20 minutes on Questions 28-40, which are based on Reading Passage 3 below.
The Power of Earthquakes
Earthquakes have inspired both fear and curiosity in people throughout history. While Q29ancient peoples used myths to explain earthquakes, modern scientists have developed the theory of plate tectonics. According to this theory, the Earth’s surface is broken into many pieces that can move against each other, causing tremors at the Earth’s surface. [Crack IELTS with Rob] To better understand these events, Q28scientists have developed sophisticated equipment to measure, record, and even begin to predict future earthquakes. While the scientists of today may understand a great deal more than our ancestors did, they also recognize that there is still much to learn about the destructive powers held deep within the Earth.
Before scientific explanations were established, many cultures explained earth quakes by attributing them to the movements of mythical creatures, such as frogs, turtles, and even flea-infested dogs. Q30Japanese mythology tells of a great cat fish guarded by the deity Kashima. When Kashima let his guard down, the cat fish thrashed about, causing the Earth to tremble. [Crack IELTS with Rob] In India, myths tell of the Earth being held upon the shoulders of an elephant that shook its head when tired. The Greeks believed that the shaking of the Earth was the rumbling of the god Poseidon’s horses traveling through the skies or across the Earth. Or it was caused by Poseidon pounding his trident on the ground. Q32The number and vari ety of these mythological explanations for earthquakes show how important it has always been to people everywhere to understand what causes the mysterious shakings of the Earth.
Beginning in the early 1960s, many in the scientific community began espous ing the theory of plate tectonics, which explains that Q39the surface of the Earth, the crust, is broken into many pieces called tectonic plates. Some of these plates are extremely large, such as the Eurasian Plate, on which sits most of Europe and Asia. Others are smaller, such as Q33the Caribbean Plate, which is mostly under water in the Caribbean Sea. [Crack IELTS with Rob] Q35These plates float on the Earth’s mantle, a bed of molten rock called magma. Deeper forces inside the Earth’s core heat this magma and cause it to flow underneath the plates, pushing the plates. The tension created at the boundaries of opposing plates can often become strong enough to snap them past each other, sometimes with the violent force that we know as an earthquake.
Scientists describe the movement of the plates in relation to each other in three principal ways. First, when two plates are forced into each other, one plate slides below the other. This is known as a convergent boundary. As the lower plate goes down, the upper plate often rises, forming mountains. Q37The Himalayas, for example, were formed by the Indian Plate crashing into the Eurasian Plate. Q38The second type of boundary is where two plates move apart from each other. [Crack IELTS with Rob] This is known as a divergent boundary. An example of this is the Mid-Atlantic Rift, found at the bottom of the Atlantic Ocean. At this boundary, the North American Plate and the Eurasian plate are being forced apart, at an average rate of 2.5 centimeters1 per year. Q34The third type is a transform boundary, where the edges of two plates slide in opposite directions parallel to each other. When the pressure between these plates is great enough, they snap violently past each other. This type of interaction between plates is the cause of many of the earthquakes felt in California.
Seismologists, Q40the scientists who study earthquakes, use a device called a seismograph to measure the force of earthquakes and tremors. The most sophisticated of these are capable of measuring even the slightest tremor and locating its origin. The measuring system most commonly used is called the Richter Scale. It was invented in 1935 by a seismologist named Charles F. Richter. Because the difference in power between small and large earthquakes is so great, he developed a logarithmic scale in which an increase of one on the scale represents a tenfold increase in power. [Crack IELTS with Rob] This means that Q36an earthquake with a magnitude of 4.0, which would be easily felt at the Earth’s surface, is ten times more powerful than a magnitude 3.0 quake and 100 times more powerful than a magnitude 2.0 quake, which often goes unnoticed. The data the scientists collect allow them not only to document past earthquakes, but to learn to predict future events.
While scientists today know much more about earthquakes than ever, there is still much to be learned. Seismologists have helped us understand more about how earthquakes happen and why they occur in some parts of the world but not others. All of this knowledge informs us about our Earth and protects us from some of the potential dangers. There are still, however, many forces in the Earth that we do not understand, with the potential to move, shake, and reshape the world.
Questions 28 - 33
Choose the correct letter, A, B, C or D.
Write your correct answer, A-D, on your answer sheet.
28. Modern scientists are
29. In ancient times, people explained earthquakes by
30. Kashima was a
31. The ancient Greeks believed that earthquakes were caused by a god’s
32. The quantity and diversity of explanations for earthquakes from ancient cultures show that
33. The Caribbean Plate
Questions 34 - 40
Complete each sentence with the correct ending from the list below.
Write the correct letter, A-J, on boxes 34 – 40 on your answer sheet.
List of statements
A a convergent boundary
B a seismograph
C a transform boundary
D an earthquake measuring 2.0
E a logarithmic scale
F a divergent boundary
G a magnitude 3.0 earthquake
H a layer of magma
I a collision between two plates
J a piece of the Earth’s crust
34. A place where two plates slide in opposite directions is calledC
35. Tectonic plates lie onH
36. An earthquake measuring 4.0 is ten times more powerful thanG
37. The Himalayas were caused byI
38. The Mid-Atlantic Rift is an example ofF
39. A tectonic plate isJ
40. The machine used to measure the strength of earthquakes is known asB